Encoder, decoder, and corresponding method

Abstract

This provides a method for decoding an encoded video bitstream. [Solution] The decoding method includes the steps of: obtaining a picture-level syntax element from the picture header of the current picture that specifies whether an adaptive loop filter (ALF) is enabled for the current picture; and, if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, obtaining a parameter set identifier contained in the picture header. The parameter set identifier is used to indicate a first parameter set containing a set of ALF parameters, wherein the time identifier of the first parameter set is less than or equal to the time identifier of the current picture. The method further includes the step of performing the adaptive loop filter on at least one slice of the current picture based on the first parameter set.

Description

Technical Field

[0001] Cross - reference to Related Applications This application is a continuation application of International Application No. PCT / CN2020 / 070155, filed on January 2, 2020, which is a continuation application of International Application No. PCT / CN2019 / 130581, filed on December 31, 2019. The disclosures of the above - mentioned applications are hereby incorporated by reference in their entireties into this specification.

[0002] Embodiments of the present application (disclosure) generally relate to the field of picture processing, and more particularly, to high - level syntax elements.

Background Art

[0003] Video coding (video encoding and decoding) is used in a wide range of digital video applications, such as broadcast digital TV, video transmission over the Internet and mobile networks, real - time conversation applications such as video chat, video conferencing, DVDs and Blu - ray discs, video content acquisition and editing systems, and camcorders for security applications.

[0004] Even relatively short videos can require a considerable amount of video data, which can pose challenges when the data needs to be streamed or otherwise transmitted over communication networks with limited bandwidth. Therefore, video data is generally compressed before being transmitted over modern communication networks. Video size can also be a concern when video is stored on a storage device, as memory resources may be limited. Often, video compression devices use software and / or hardware at the source to encode the video data before transmission or storage, thereby reducing the amount of data required to represent the digital video image. The compressed data is then received at the destination by a video decompression device that decodes the video data. Given limited network resources and the increasing demand for higher video quality, improved compression and decompression techniques that increase the compression ratio with little to no sacrifice of picture quality are desirable. [Overview of the project] [Means for solving the problem]

[0005] Embodiments of this application provide apparatus and methods for encoding and decoding according to independent claims.

[0006] The other objectives described above are achieved by the subject matter of the independent claims. Further forms of implementation are evident from the dependent claims, specification, and drawings.

[0007] According to a first aspect, the Disclosure relates to a method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing the current picture, and the decoding method comprises the steps of: parsing the video bitstream to obtain a picture-level syntax element contained in the picture header of the current picture, the picture-level syntax element being used to specify whether an adaptive loop filter (ALF) is enabled for the current picture; if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, obtaining a parameter set identifier contained in the picture header, the parameter set identifier being used to indicate a first parameter set containing a set of ALF parameters, the temporal identifier of the first parameter set being less than or equal to the temporal identifier of the current picture; and performing the adaptive loop filter on at least one slice of the current picture based on the first parameter set.

[0008] A picture header is a syntax structure containing syntax elements that apply to all slices of a coded picture. A syntax structure consists of zero or more syntax elements that exist together in a bitstream in a specified order, and syntax elements are elements of the data represented in the bitstream.

[0009] The first parameter set is the adaptive parameter set (APS), which is a syntactic structure.

[0010] The current picture is a coded picture contained within a picture unit (PU), where a PU is a set of NAL units that are related to each other according to a specified classification rule and are consecutive in decoding order.

[0011] A network abstraction layer (NAL) unit is a syntactic structure that includes an indication of the type of data that follows, and bytes containing the data or a portion of the data of the current picture, a picture header, or a parameter set containing a set of ALF parameters. Here, each NAL unit has a time identifier.

[0012] If the time identifier of the first NAL unit is less than the time identifier of the second NAL unit in the same layer, the data encapsulated by the first NAL unit may be decoded without referencing the data encapsulated by the second NAL unit. The time identifier may also be used in a sub-bitstream extraction process, which is a process in which NAL units in a bitstream that do not belong to the target set determined by the target highest time identifier are removed from the bitstream, and the output sub-bitstream consists of NAL units in bitstreams that belong to the target set. Therefore, the fact that the time identifier of the first parameter set is less than or equal to the time identifier of the current picture may allow referencing the first parameter set when decoded from the current picture, or may enable a sub-bitstream extraction process for the current picture.

[0013] The time identifier may be related to the decoding order.

[0014] In a possible implementation of the method according to the first embodiment, the step of performing an adaptive loop filter on at least one slice of the current picture based on a first set of parameters includes performing an adaptive loop filter on the luma component of at least one slice of the current picture based on the first set of parameters.

[0015] In any of the above-described implementations of the first aspect or in a possible implementation of the method according to the first aspect itself, the method further includes the step of obtaining another parameter set identifier contained in the picture header, where the picture-level syntax element specifies that an adaptive loop filter is to be enabled for the current picture, the parameter set identifier being used to indicate a second parameter set containing a set of ALF parameters, and the time identifier of the second parameter set being less than or equal to the time identifier of the current picture, and the step of performing an adaptive loop filter on the chroma components of at least one slice of the current picture based on the second parameter set.

[0016] The second parameter set is the Adaptive Parameter Set (APS), which is a syntactic structure.

[0017] In a second aspect, the Disclosure relates to a method for encoding a video bitstream performed by an encoding device, wherein the video bitstream includes data representing the current picture, and the encoding method includes the steps of: determining whether an adaptive loop filter (ALF) is enabled for the current picture; encoding a picture-level syntax element in the picture header of the current picture based on the determination of whether an adaptive loop filter (ALF) is enabled for the current picture, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture; and, if the adaptive loop filter is enabled for the current picture, encoding a parameter set identifier in the picture header, wherein the parameter set identifier is used to indicate a first parameter set containing a set of ALF parameters for the adaptive loop filter, and the time identifier of the first parameter set is set to be less than or equal to the time identifier of the current picture.

[0018] The step of determining whether an Adaptive Loop Filter (ALF) is enabled for the current picture may include comparing the cost of running the Adaptive Loop Filter (ALF) for at least one block of the current picture with the cost of not running the Adaptive Loop Filter (ALF) for the current picture, and determining that the Adaptive Loop Filter (ALF) is disabled for the current picture if the cost of running the Adaptive Loop Filter (ALF) for at least one block of the current picture is greater than or equal to the cost of running the Adaptive Loop Filter (ALF) for at least one block of the current picture, and otherwise determining that the Adaptive Loop Filter (ALF) is enabled for the current picture. The cost may be the rate distortion cost.

[0019] In a possible implementation of the method according to the second aspect itself, the method further includes the step of encoding the time identifier of the first parameter set and the time identifier of the current picture into a video bitstream.

[0020] In any of the above-described implementations of the second aspect, or in a possible implementation of the method according to the second aspect itself, the first parameter set includes a set of ALF parameters for an adaptive loop filter that is performed on the luma component of at least one slice of the current picture.

[0021] In any of the above-described implementations of the second aspect or in a possible implementation of the method according to the second aspect itself, the method further includes the step of encoding another parameter set identifier in the picture header when a picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, the parameter set identifier is used to indicate a second parameter set containing a set of ALF parameters for an adaptive loop filter performed on the chroma components of at least one slice of the current picture, and the time identifier of the second parameter set is set to be less than or equal to the time identifier of the current picture.

[0022] According to a third aspect, the disclosure relates to an apparatus for decoding a coded video bitstream. The apparatus includes an acquisition unit configured to acquire a picture-level syntax element contained in the picture header of the current picture by parsing a video bitstream, the picture-level syntax element being used to specify whether an adaptive loop filter (ALF) is enabled for the current picture. The acquisition unit is further configured to acquire a parameter set identifier contained in the picture header if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, the parameter set identifier being used to indicate a first parameter set containing a set of ALF parameters, the time identifier of the first parameter set being less than or equal to the time identifier of the current picture, and a filtering unit being configured to perform an adaptive loop filter on at least one slice of the current picture based on the first parameter set.

[0023] In a possible implementation of the apparatus according to the third embodiment itself, the filtering unit is configured to perform an adaptive loop filter on the luma component of at least one slice of the current picture based on a first set of parameters.

[0024] In any of the above-described implementations of the third aspect or in a possible implementation of the device by the third aspect itself, the acquisition unit is further configured to acquire another parameter set identifier contained in the picture header if the picture-level syntax element specifies that an adaptive loop filter should be enabled for the current picture, the parameter set identifier is used to indicate a second parameter set containing a set of ALF parameters, the time identifier of the second parameter set being less than or equal to the time identifier of the current picture, and the filtering unit is configured to perform an adaptive loop filter on the chroma components of at least one slice of the current picture based on the second parameter set.

[0025] According to a fourth aspect, the present disclosure relates to an apparatus for encoding a coded video bitstream. The apparatus includes a determination unit configured to determine whether an adaptive loop filter (ALF) is enabled for a current picture, and an encoding unit configured to encode a picture level syntax element into a picture header of the current picture based on whether the adaptive loop filter (ALF) is enabled for the current picture, wherein the picture level syntax element is used to specify whether the adaptive loop filter (ALF) is enabled for the current picture. The encoding unit is further configured to encode a parameter set identifier into the picture header when the adaptive loop filter is enabled for the current picture, where the parameter set identifier is used to indicate a first parameter set including a set of ALF parameters of the adaptive loop filter, and a temporal identifier of the first parameter set is set to be less than or equal to a temporal identifier of the current picture.

[0026] In a possible implementation form of the apparatus according to the fourth aspect itself, the encoding unit is further configured to encode a temporal identifier of the first parameter set and a temporal identifier of the current picture into the video bitstream.

[0027] In any of the above implementations of the fourth aspect or in a possible implementation form of the apparatus according to the fourth aspect itself, the first parameter set includes a set of ALF parameters of the adaptive loop filter to be executed on at least one slice's luma component of the current picture.

[0028] In any of the above-described implementations of the fourth aspect or in a possible implementation of the apparatus by the fourth aspect itself, the encoding unit is further configured to encode another parameter set identifier in the picture header if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, the parameter set identifier is used to indicate a second parameter set containing a set of ALF parameters for an adaptive loop filter performed on the chroma components of at least one slice of the current picture, and the time identifier of the second parameter set is set to be less than or equal to the time identifier of the current picture.

[0029] A method according to the first aspect of this disclosure may be carried out by an apparatus according to the third aspect of this disclosure. Further features and implementations of the method according to the first aspect of this disclosure correspond to features and implementations of the apparatus according to the third aspect of this disclosure.

[0030] The method according to the second aspect of this disclosure may be carried out by the apparatus according to the fourth aspect of this disclosure. Further features and implementations of the method according to the second aspect of this disclosure correspond to features and implementations of the apparatus according to the fourth aspect of this disclosure.

[0031] The method according to the second embodiment can be extended to an implementation form corresponding to an implementation form of the method according to the first embodiment. Therefore, the implementation form of the method includes the features of the corresponding implementation form of the first embodiment.

[0032] The advantages of the method according to the second embodiment are the same as the advantages of the corresponding implementation form of the method according to the first embodiment.

[0033] According to a fifth aspect, the disclosure relates to an apparatus for decoding a video stream, including a processor and memory. The memory stores instructions causing the processor to perform a method according to the first aspect or any implementation thereof.

[0034] According to the sixth aspect, the disclosure relates to an apparatus for encoding a video stream, including a processor and memory. The memory stores instructions causing the processor to perform a method according to the second aspect or any implementation thereof.

[0035] According to the seventh aspect, a computer-readable storage medium is proposed that stores instructions causing one or more processors to code video data when executed. The instructions cause one or more processors to execute a method according to the first or second aspect or any implementation thereof.

[0036] According to the eighth aspect, the disclosure relates to a computer program which includes program code for performing the first or second aspect or any implementation thereof when executed on a computer.

[0037] According to the ninth aspect, the present disclosure relates to a decoder including a processing circuit for performing the method according to the first aspect or any implementation thereof.

[0038] According to the tenth aspect, the present disclosure relates to an encoder including a processing circuit for performing the method according to the second aspect or any implementation thereof.

[0039] In an eleventh aspect, the disclosure relates to a non-temporary storage medium comprising an encoded bitstream decoded by an image decoding device, wherein the bitstream is generated by dividing a current picture of a video or image signal into a plurality of blocks and comprises a plurality of syntax elements, the plurality of syntax elements comprising a picture-level syntax element contained in the picture header of the current picture, obtained by parsing a video bitstream, the picture-level syntax element being used to specify whether an adaptive loop filter (ALF) is enabled for the current picture, and if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, the bitstream further comprises a parameter set identifier contained in the picture header, the parameter set identifier being used to indicate a first parameter set comprising a set of ALF parameters, and the time identifier of the first parameter set being set to be less than or equal to the time identifier of the current picture.

[0040] Specific embodiments are described in the appended independent claims, and other embodiments are shown in the dependent claims.

[0041] Details of one or more embodiments are described in the accompanying drawings and the following description. Other features, purposes, and advantages will become apparent from the specification, drawings, and claims.

[0042] Furthermore, the following embodiments are provided.

[0043] In one embodiment, a bitstream for video coding is provided, and the DPS is present in the bitstream at most once.

[0044] In one embodiment, DPS is not essential to the bitstream.

[0045] In one embodiment, when the bitstream includes DPS, only one DPS is present in the bitstream.

[0046] In one embodiment, all DPS NAL units in the bitstream that have a specific value for dps_decoding_parameter_set_id have the same content.

[0047] In one embodiment, a single DPS ID cannot hook into the contents of two or more DPS.

[0048] In one embodiment, a bitstream for video coding is provided, which is constrained such that the level signaled by DPS is greater than or equal to the level signaled by SPS.

[0049] In one embodiment, a coding method is provided that is performed by a decoding device, comprising the step of analyzing a bitstream according to any one of the embodiments described above.

[0050] In one embodiment, a coding method performed by an encoding device is provided, which includes the step of generating a bitstream according to any one of the embodiments described above.

[0051] In one embodiment, an encoder (20) is provided that includes a processing circuit for performing a method according to any one of the embodiments described above.

[0052] In one embodiment, a decoder (30) is provided that includes a processing circuit for performing a method according to any one of the embodiments described above.

[0053] In one embodiment, a computer program product is provided which includes program code for performing the method according to any one of the above embodiments when executed on a computer or processor.

[0054] In one embodiment, One or more processors, A decoder is provided, comprising a non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the decoder is configured such that the program, when executed by the processor, performs the method according to any one of the embodiments described above.

[0055] In one embodiment, One or more processors, An encoder is provided, comprising a non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the encoder is configured such that the program, when executed by the processor, performs the method according to any one of the embodiments described above.

[0056] In one embodiment, a non-temporary computer-readable medium is provided that, when executed by a computer device, carries program code causing the computer device to perform the method according to any one of the embodiments described above.

[0057] In one embodiment, a method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing coded pictures including a tile sequence, and the decoding method is A step of obtaining a syntax element (e.g., tile_column_width_minus1) by parsing a video bitstream, wherein the syntax element is used to derive the width of the tile column, and the sum of the widths of the tile column is less than or equal to the width of the coded picture. A method is provided which includes the step of predicting a picture coded by the width of a tile column.

[0058] In one embodiment, the value obtained by adding 1 to the value of each syntax element is the width of one of the tile columns.

[0059] In one embodiment, the width of the tile column has an index i within the range of 0 to num_exp_tile_columns_minus1 - 1.

[0060] In one embodiment, the width of the tile column has an index i within the range of 0 to num_exp_tile_columns_minus1.

[0061] In one embodiment, a method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing coded pictures including a tile sequence, and the decoding method is A step of obtaining a syntax element (e.g., tile_column_width_minus1) by parsing a video bitstream, wherein the syntax element is used to derive a value for the width of the tile column, the value for the width of the tile column is uniform, and the value for the width of the tile column is less than or equal to the width of the coded picture. A method is provided which includes the step of predicting a picture coded by the width of a tile column.

[0062] In one embodiment, the value obtained by adding 1 to the value of the syntax element is the width of the tile column.

[0063] In one embodiment, the width of a tile column has an index i equal to num_exp_tile_columns_minus1.

[0064] In one embodiment, a method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing coded pictures including tile rows, and the decoding method is A step of obtaining a syntax element (e.g., tile_row_height_minus1) by parsing a video bitstream, wherein the syntax element is used to derive the height of the tile rows, and the sum of the heights of the tile rows is less than or equal to the height of the coded picture. A method is provided that includes the step of predicting a coded picture based on the height of a tile row.

[0065] In one embodiment, the value obtained by adding 1 to the value of each syntax element is the height of the tile row.

[0066] In one embodiment, the height of a tile row has an index i within the range of 0 to num_exp_tile_rows_minus1 - 1.

[0067] In one embodiment, the height of a tile row has an index i within the range of 0 to num_exp_tile_rows_minus1.

[0068] In one embodiment, a method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing coded pictures including tile rows, and the decoding method is A step of obtaining a syntax element, e.g., tile_row_height_minus1) by parsing a video bitstream, wherein the syntax element is used to derive a value for the height of the tile row, the value for the height of the tile row is uniform, and the value for the height of the tile row is less than or equal to the height of the coded picture. A method is provided which includes the step of predicting a picture coded by the height of a tile row.

[0069] In one embodiment, the value obtained by adding 1 to the value of the syntax element is the height of the tile row.

[0070] In one embodiment, the height of a tile row has an index i equal to num_exp_tile_rows_minus1.

[0071] In one embodiment, an encoder (20) is provided that includes a processing circuit for performing a method according to any one of the embodiments described above.

[0072] In one embodiment, a decoder (30) is provided that includes a processing circuit for performing a method according to any one of the embodiments described above.

[0073] In one embodiment, a computer program product is provided which includes program code for performing the method according to any one of the above embodiments when executed on a computer or processor.

[0074] In one embodiment, One or more processors, A decoder is provided, comprising a non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the decoder is configured such that the program, when executed by the processor, performs the method according to any one of the embodiments described above.

[0075] In one embodiment, One or more processors, An encoder is provided, comprising a non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the encoder is configured such that the program, when executed by the processor, performs the method according to any one of the embodiments described above.

[0076] In one embodiment, a non-temporary computer-readable medium is provided that, when executed by a computer device, carries program code causing the computer device to perform the method according to any one of the embodiments described above.

[0077] Embodiments of the invention will be described in more detail below with reference to the accompanying figures and drawings. [Brief explanation of the drawing]

[0078] [Figure 1A] This is a block diagram showing an example of a video coding system configured to implement an embodiment of the present invention. [Figure 1B] This is a block diagram showing another example of a video coding system configured to implement embodiments of the present invention. [Figure 2] This is a block diagram showing an example of a video encoder configured to implement an embodiment of the present invention. [Figure 3] This is a block diagram illustrating an exemplary structure of a video decoder configured to implement embodiments of the present invention. [Figure 4] This is a block diagram showing examples of encoding or decoding devices. [Figure 5] This is a block diagram showing another example of an encoding or decoding device. [Figure 6] This is a block diagram showing an exemplary structure of a content supply system 3100 that realizes a content distribution service. [Figure 7] This is a block diagram showing the structure of an example terminal device. [Figure 8] This is a flowchart of a decoding method according to one embodiment. [Figure 9] This is a flowchart of an encoding method according to one embodiment. [Figure 10] This is a schematic diagram of an encoder according to one embodiment. [Figure 11] This is a schematic diagram of a decoder according to one embodiment. [Modes for carrying out the invention]

[0079] In the following, unless otherwise specified, the same reference numeral refers to the same or at least functionally equivalent feature.

[0080] In the following description, references are made to the accompanying drawings, which form part of this disclosure and illustrate specific embodiments of the invention or specific embodiments of the invention in which they may be used. It is understood that embodiments of the invention may be used in other embodiments and may include structural or logical modifications not shown in the drawings. Accordingly, the following detailed description should not be understood to be restrictive, and the scope of the invention is defined by the appended claims.

[0081] For example, disclosures relating to a described method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, if one or more steps of a particular method are described, a corresponding device may include one or more units for performing the steps of the described method, e.g., functional units (e.g., one unit performing one or more steps, or multiple units each performing one or more of the steps), even if such one or more units are not explicitly described or shown in the figures. Conversely, if a particular apparatus is described based on one or more units, e.g., functional units, a corresponding method may include one step for performing the function of one or more units (e.g., one step performing the function of one or more units, or multiple steps each performing one or more of the functions of multiple units), even if such one or more steps are not explicitly described or shown in the figures. Furthermore, it is understood that the various exemplary embodiments and / or features of the aspects described herein may be combined with each other unless otherwise specified.

[0082] Video coding generally refers to the processing of a sequence of pictures that make up a video or video sequence. Instead of the term "picture," the terms "frame" or "image" may be used as synonyms in the field of video coding. Video coding (or coding in general) consists of two parts: video encoding and video decoding. Video encoding is performed on the source side and generally involves processing the original video picture (e.g., by compression) to reduce the amount of data required to represent the video picture (for more efficient storage and / or transmission). Video decoding is performed on the destination side and generally involves the reverse processing compared to the encoder to reconstruct the video picture. Embodiments referring to "coding" of a video picture (or picture in general) are understood to be relating to the "encoding" or "decoding" of the video picture or each video sequence. The combination of the encoding and decoding parts is also called a codec (coding and decoding).

[0083] In lossless video coding, the original video picture can be reconstructed (assuming there is no transmission loss or other data loss during storage or transmission), meaning the reconstructed video picture will have the same quality as the original. In lossy video coding, further compression is performed, for example, by quantization, to reduce the amount of data representing the video picture, which cannot be fully reconstructed in the decoder, meaning the quality of the reconstructed video picture will be lower or worse than the quality of the original video picture.

[0084] Some video coding standards belong to the group of "lossy hybrid video codecs" (i.e., they combine spatial and temporal prediction in the sample domain with 2D transform coding to apply quantization in the transform domain). Each picture in a video sequence is generally divided into a set of non-overlapping blocks, and coding is generally performed at the block level. In other words, in an encoder, video is generally processed at the block (video block) level, i.e., encoded, by generating prediction blocks using, for example, spatial (intra-picture) and / or temporal (inter-picture) predictions, obtaining residual blocks by subtracting the prediction blocks from the current blocks (the blocks currently being processed), transforming the residual blocks, and quantizing the residual blocks in the transform domain to reduce (compress) the amount of data being transmitted. In a decoder, the reverse process compared to the encoder is applied to the encoded or compressed blocks in order to reconstruct the current blocks for representation. Furthermore, the encoder duplicates the decoder's processing loop to process subsequent blocks, i.e., to generate identical predictions (e.g., intra and inter predictions) and / or reconstructions for coding.

[0085] Embodiments of the video coding system 10, video encoder 20, and video decoder 30 are described below with reference to Figures 1 to 3.

[0086] Figure 1A is a schematic block diagram showing an exemplary coding system 10 that may utilize the technology of the present application, for example, a video coding system 10 (or coding system 10 in short). The video encoder 20 (or encoder 20 in short) and video decoder 30 (or decoder 30 in short) of the video coding system 10 show examples of devices that may be configured to perform the technology described in the various examples in this application.

[0087] As shown in Figure 1A, the coding system 10 includes a source device 12 configured to provide encoded picture data 21 to a destination device 14, for example, in order to decode the encoded picture data 13.

[0088] The source device 12 includes an encoder 20 and may additionally, or optionally, include a picture source 16, a preprocessor (or preprocessing unit) 18, for example, a picture preprocessor 18, and a communication interface or communication unit 22.

[0089] The picture source 16 may include or be any type of picture-taking device, e.g., a camera for taking pictures of the real world, and / or any type of picture-generating device, e.g., a computer graphics processor for generating computer-animated pictures, or any other type of device for acquiring and / or providing pictures of the real world, computer-generated pictures (e.g., screen content, virtual reality (VR) pictures), and / or any combination thereof (e.g., augmented reality (AR) pictures). The picture source may be any type of memory or storage for storing any of the pictures described above.

[0090] To distinguish it from the processing performed by the preprocessor 18 and the preprocessing unit 18, the picture or picture data 17 may also be called the raw picture or raw picture data 17.

[0091] The preprocessor 18 is configured to receive (raw) picture data 17 and perform preprocessing on the picture data 17 to obtain a preprocessed picture 19 or preprocessed picture data 19. The preprocessing performed by the preprocessor 18 may include, for example, cropping, color format conversion (e.g., from RGB to YCbCr), color correction, or denoising. It can be understood that the preprocessing unit 18 may be an arbitrary component.

[0092] The video encoder 20 is configured to receive pre-processed picture data 19 and provide encoded picture data 21 (further details are described below, for example, based on Figure 2).

[0093] The communication interface 22 of the source device 12 may be configured to receive the encoded picture data 21 and transmit the encoded picture data 21 (or any further processed version thereof) via the communication channel 13 to another device, such as the destination device 14 or any other device, for storage or direct reconstruction.

[0094] The destination device 14 includes a decoder 30 (for example, a video decoder 30) and may additionally, or optionally, include a communication interface or communication unit 28, a post-processor 32 (or post-processing unit 32), and a display device 34.

[0095] The communication interface 28 of the destination device 14 is configured to receive encoded picture data 21 (or any further processed version thereof) directly from the source device 12 or from any other source, such as a storage device, such as a storage device for encoded picture data, and to provide the encoded picture data 21 to the decoder 30.

[0096] Communication interfaces 22 and 28 may be configured to transmit or receive encoded picture data 21 or encoded data 13 via a direct communication link between the source device 12 and the destination device 14, for example, via a direct wired or wireless connection, or via any type of network, for example, a wired or wireless network or any combination thereof, or any type of private and public network, or any type of combination thereof.

[0097] The communication interface 22 may be configured to process the encoded picture data using any kind of encoding or processing for transmission, such as packaging the encoded picture data 21 into an appropriate format, for example, packets, and / or transmitting it over a communication link or communication network.

[0098] The communication interface 28 that forms the counterpart to the communication interface 22 may be configured, for example, to receive transmitted data and process the transmitted data using any kind of corresponding decryption or processing and / or depackaging of the transmission to obtain encoded picture data 21.

[0099] Both communication interface 22 and communication interface 28 may be configured as unidirectional or bidirectional communication interfaces, as indicated by the arrows relating to communication channel 13 in Figure 1A pointing from source device 12 to destination device 14, and may be configured, for example, to set up a connection and to send and receive messages to confirm and exchange any other information related to the communication link and / or data transmission, such as the transmission of encoded picture data.

[0100] The decoder 30 is configured to receive the encoded picture data 21 and provide the decoded picture data 31 or the decoded picture 31 (further details are described below, for example, based on Figure 3 or Figure 5).

[0101] The post-processor 32 of the destination device 14 is configured to obtain post-processed picture data 33, for example, a post-processed picture 33, by post-processing the decoded picture data 31 (also called reconstructed picture data), for example, the decoded picture 31. Post-processing performed by the post-processing unit 32 may include, for example, color format conversion (e.g., from YCbCr to RGB), color correction, cropping, or resampling, or any other processing to prepare the decoded picture data 31 for display by, for example, the display device 34.

[0102] The display device 34 of the destination device 14 is configured to receive, for example, picture data 33 that has been post-processed for displaying the picture to a user or viewer. The display device 34 may be any type of display for showing the reconstructed picture, for example, an integrated or external display or monitor, or may include such a display or monitor. The display may include, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a plasma display, a projector, a microLED display, a liquid crystal on silicon (LCoS), a digital light processor (DLP), or any other type of display.

[0103] Figure 1A shows the source device 12 and destination device 14 as separate devices, but the device embodiment may include both or both functions, such as the source device 12 or its corresponding function and the destination device 14 or its corresponding function. In such embodiments, the source device 12 or its corresponding function and the destination device 14 or its corresponding function may be implemented using the same hardware and / or software, or by separate hardware and / or software, or any combination thereof.

[0104] As will become apparent to those skilled in the art based on the description, the functions of different units or the presence and (strict) division of functions within the source device 12 and / or destination device 14 shown in Figure 1A may vary depending on the actual device and application.

[0105] The encoder 20 (e.g., video encoder 20) or the decoder 30 (e.g., video decoder 30), or both the encoder 20 and the decoder 30, may be implemented by the processing circuitry shown in Figure 1B, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, or any combination thereof dedicated to video coding. The encoder 20 may be implemented by the processing circuitry 46 to embody various modules considered in relation to the encoder 20 of Figure 2 and / or any other encoder system or subsystem described herein. The decoder 30 may be implemented by the processing circuitry 46 to embody various modules considered in relation to the decoder 30 of Figure 3 and / or any other decoder system or subsystem described herein. The processing circuitry may be configured to perform various operations, which will be considered later. As shown in Figure 5, if the technology is partially implemented in software, the device may store instructions for the software in a suitable non-temporary computer-readable storage medium and execute the instructions in hardware that uses one or more processors to perform the technology of this disclosure. Either the video encoder 20 or the video decoder 30 may be incorporated as part of a combined encoder / decoder (codec) in a single device, for example, as shown in Figure 1B.

[0106] The source device 12 and destination device 14 may include any type of handheld or stationary device, including a wide range of devices such as notebook or laptop computers, mobile phones, smartphones, tablets or tablet computers, cameras, desktop computers, set-top boxes, televisions, display devices, digital media players, video game consoles, video streaming devices (such as content service servers or content distribution servers), broadcast receiver devices, and broadcast transmitter devices, and may or may not use an operating system. In some cases, the source device 12 and destination device 14 may be wireless communication devices. Therefore, the source device 12 and destination device 14 may be wireless communication devices.

[0107] In some cases, the video coding system 10 shown in Figure 1A is merely an example, and the techniques of this disclosure may apply to video coding situations (e.g., encoding or decoding video) that do not necessarily involve any data communication between the encoding device and the decoding device. In other examples, the data may be retrieved from local memory or streamed over a network. The video encoding device may encode the data and store it in memory, and / or the video decoding device may retrieve the data from memory and decode it. In some examples, encoding and decoding are performed by devices that do not communicate with each other, but simply encode the data into memory and / or retrieve the data from memory and decode it.

[0108] For convenience of explanation, embodiments of the present invention are described herein by reference to, for example, reference software for next-generation video coding standards developed by the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Motion Picture Experts Group (MPEG) Joint Collaboration Team on Video Coding (JCT-VC). Those skilled in the art will understand that embodiments of the present invention are not limited to HEVC or VVC.

[0109] Encoder and encoding method Figure 2 shows a schematic block diagram of an exemplary video encoder 20 configured to implement the technology of the present application. In the example of Figure 2, the video encoder 20 includes an input 201 (or input interface 201), a residual calculation unit 204, a transformation unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transformation unit 212, a reconstruction unit 214, a loop filter unit 220, a decoded picture buffer (DPB) 230, a mode selection unit 260, an entropy coding unit 270, and an output 272 (or output interface 272). The mode selection unit 260 may include an inter-prediction unit 244, an intra-prediction unit 254, and a partitioning unit 262. The inter-prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The video encoder 20 shown in Figure 2 may also be called a hybrid video encoder or a video encoder with a hybrid video codec.

[0110] The residual calculation unit 204, the conversion processing unit 206, the quantization unit 208, and the mode selection unit 260 can be considered to form the forward signal path of the encoder 20, while the inverse quantization unit 210, the inverse conversion processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoding picture buffer (DPB) 230, the inter-prediction unit 244, and the intra-prediction unit 254 can be considered to form the reverse signal path of the video encoder 20, and the reverse signal path of the video encoder 20 corresponds to the signal path of the decoder (see video decoder 30 in Figure 3). The inverse quantization unit 210, the inverse conversion processing unit 212, the reconstruction unit 214, the loop filter 220, the decoding picture buffer (DPB) 230, the inter-prediction unit 244, and the intra-prediction unit 254 can also be considered to form the “built-in decoder” of the video encoder 20.

[0111] Picture & Picture Separation (Picture & Block) The encoder 20 may be configured to receive, for example, a picture 17 (or picture data 17) via input 201, for example, a picture of a sequence of pictures that form a video or video sequence. The received picture or picture data may also be a pre-processed picture 19 (or pre-processed picture data 19). For simplicity, the following description will refer to picture 17. Picture 17 may also be called the current picture or the picture being coded (particularly in video coding to distinguish the current picture from other pictures, for example, already coded and / or coded pictures of the same video sequence, i.e., the video sequence that also contains the current picture).

[0112] A (digital) picture can be considered, or may be considered, a two-dimensional array or matrix of samples having intensity values. A sample in an array may also be called a pixel (a shortened form of picture element) or pel. The number of samples in the horizontal and vertical (or axis) directions of an array or picture defines the size and / or resolution of the picture. For color representation, generally three color components are used, meaning a picture may be represented by or contain three sample arrays. In the RGB format or color space, a picture contains corresponding red, green, and blue sample arrays. However, in video coding, each pixel is generally represented by a luminance and chrominance format or color space, for example, YCbCr, which includes a luminance component represented by Y (sometimes L is used instead) and two chrominance components represented by Cb and Cr. The luminance (or luma) component Y represents the brightness or intensity of the gray level (for example, as in a grayscale picture), while the two chrominance (or chroma) components Cb and Cr represent the chromaticity or color information components. Therefore, a picture in YCbCr format contains a luminance sample array of luminance sample values ​​(Y) and two chrominance sample arrays of chrominance values ​​(Cb and Cr). A picture in RGB format can be converted to or transformed into YCbCr format, and vice versa; the process is also known as transformation or conversion. If a picture is monochrome, it may contain only a luminance sample array. Thus, a picture may be, for example, a luma sample array in a monochrome format, or a luma sample array and two corresponding chroma sample arrays in 4:2:0, 4:2:2, and 4:4:4 color formats.

[0113] Embodiments of the video encoder 20 may include a picture partitioning unit (not shown in Figure 2) configured to partition a picture 17 into multiple (typically non-overlapping) picture blocks 203. These blocks may also be called root blocks, macroblocks (H.264 / AVC), or coding tree blocks (CTB) or coding tree units (CTU) (H.265 / HEVC and VVC). The picture partitioning unit may use the same block size for all pictures and corresponding grids that define the block size for all pictures in the video sequence, or it may be configured to change the block size between pictures or subsets or groups of pictures, partitioning each picture into its corresponding block.

[0114] In a further embodiment, the video encoder may be configured to directly receive a block 203 of picture 17, for example, one, some, or all of the blocks that make up picture 17. The picture block 203 may also be called the current picture block or the coded picture block.

[0115] Similar to picture 17, picture block 203 is smaller in dimensions than picture 17, but can also be considered, or may be considered, a two-dimensional array or matrix of samples having intensity values ​​(sample values). In other words, block 203 may contain, depending on the color format applied, for example, one sample array (e.g., a luma array for monochrome picture 17, or a luma or chroma array for color picture), three sample arrays (e.g., a luma and two chroma arrays for color picture 17), or any other number and / or type of array. The number of samples in the horizontal and vertical (or axis) directions of block 203 defines the size of block 203. Thus, a block may be, for example, an MxN (M columns × N rows) array of samples or an MxN array of conversion coefficients.

[0116] The embodiment of the video encoder 20 shown in Figure 2 may be configured to encode the picture 17 block by block, for example, encoding and prediction being performed for each block 203.

[0117] Embodiments of the video encoder 20 shown in Figure 2 may be further configured to divide and / or encode a picture by using slices (also called video slices), the picture may be divided into one or more (generally non-overlapping) slices or encoded using one or more (generally non-overlapping) slices, each slice may contain one or more blocks (e.g., CTUs) or one or more groups of blocks (e.g., tiles (H.265 / HEVC and VVC) or bricks (VVC)).

[0118] Embodiments of the video encoder 20 shown in Figure 2 may be further configured to segment and / or encode a picture by using slice / tile groups (also called video tile groups) and / or tiles (also called video tiles), the picture may be segmented into one or more (generally non-overlapping) slice / tile groups or encoded using one or more (generally non-overlapping) slice / tile groups, each slice / tile group may, for example, contain one or more blocks (e.g., CTUs) or one or more tiles, each tile may, for example, be rectangular in shape and may contain one or more blocks (e.g., CTUs), for example, complete or fragmented blocks.

[0119] Calculation of residuals The residual calculation unit 204 may be configured to calculate the residual block 205 (also called residual 205) based on picture block 203 and prediction block 265 (further details about prediction block 265 will be given later), for example, by subtracting the sample value of prediction block 265 from the sample value of picture block 203 for each sample (for each pixel) to obtain the residual block 205 in the sample region.

[0120] conversion The transformation processing unit 206 may be configured to apply a transformation, such as a discrete cosine transform (DCT) or discrete sine transform (DST), to the sample values ​​of the residual block 205 to obtain transformation coefficients 207 in the transformation domain. The transformation coefficients 207, also called transformation residual coefficients, may represent the residual block 205 in the transformation domain.

[0121] The conversion processing unit 206 may be configured to apply an integer approximation of DCT / DST, such as the conversion specified for H.265 / HEVC. Compared to the orthogonal DCT conversion, such an integer approximation is generally scaled by a certain rate. An additional scaling factor is applied as part of the conversion process to maintain the norm of the residual blocks processed by the forward and inverse conversions. The scaling factor is generally selected based on certain constraints, such as the scaling factor being a power of 2 for the shift operation, the bit depth of the conversion coefficients, and the trade-off between accuracy and implementation cost. For example, a particular scaling factor may be specified for the inverse conversion by the inverse conversion processing unit 212 (and the corresponding inverse conversion by the inverse conversion processing unit 312 in the video decoder 30, for example), and a corresponding scaling factor for the forward conversion by the conversion processing unit 206 of the encoder 20 may be specified accordingly.

[0122] Embodiments of the video encoder 20 (each a conversion processing unit 206) may be configured to output, for example, one or more conversions of a certain type, which may be left as is or encoded or compressed by the entropy coding unit 270, so that the video decoder 30 may receive the conversion parameters and use them for decoding.

[0123] Quantization The quantization unit 208 may be configured to quantize the transformation coefficient 207 to obtain the quantized coefficient 209, for example, by applying scalar quantization or vector quantization. The quantized coefficient 209 may also be called the quantized transformation coefficient 209 or the quantized residual coefficient 209.

[0124] The quantization process may reduce the bit depth associated with some or all of the 207 conversion coefficients. For example, an n-bit conversion coefficient may be truncated to an m-bit conversion coefficient during quantization, where n is greater than m. The degree of quantization may be modified by adjusting the quantization parameter (QP). For example, with respect to scalar quantization, different scaling may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, while larger quantization step sizes correspond to coarser quantization. Applicable quantization step sizes may be indicated by the quantization parameter (QP). The quantization parameter may be an index to a predefined set of applicable quantization step sizes. For example, a small quantization parameter may correspond to finer quantization (smaller quantization step size), a large quantization parameter may correspond to coarser quantization (larger quantization step size), or vice versa. Quantization may involve division by the quantization step size, and the corresponding and / or inverse dequantization by the inverse quantization unit 210 may involve multiplication by the quantization step size. Some standards, e.g., embodiments by HEVC, may be configured to determine the quantization step size using quantization parameters. Generally, the quantization step size may be calculated based on the quantization parameters using a fixed-point approximation of the equations, which involves division. Additional multipliers may be introduced with respect to quantization and dequantization to restore the norm of the residual block, which may be modified due to the scaling used in the fixed-point approximation of the equations with respect to the quantization step size and quantization parameters. In one exemplary implementation, the scaling of the inverse transform and dequantization may be combined. Alternatively, a customized quantization table may be used and signaled, for example, from encoder to decoder within the bitstream.Quantization is an irreversible operation, and the loss increases as the quantization step size increases.

[0125] Embodiments of the video encoder 20 (each a quantization unit 208) may be configured to output quantization parameters (QP) that are either raw or encoded by the entropy coding unit 270, for example, so that the video decoder 30 may receive the quantization parameters and apply them for decoding.

[0126] inverse quantization The inverse quantization unit 210 is configured to obtain dequantized coefficients 211 by applying the inverse of the quantization scheme applied by the quantization unit 208 to the quantized coefficients, for example, based on or using the same quantization step size as the quantization unit 208. The dequantized coefficients 211 are also called dequantized residual coefficients 211 and may correspond to the conversion coefficients 207—although they are generally not identical to the conversion coefficients due to losses due to quantization.

[0127] Inverse Transform The inverse transform processing unit 212 is configured to obtain a reconstructed residual block 213 (or the corresponding dequantized coefficient 213) in the sample region by applying the inverse transform of the transform applied by the transform processing unit 206, for example, an inverse discrete cosine transform (DCT) or an inverse discrete sine transform (DST) or other inverse transform. The reconstructed residual block 213 may also be called a transform block 213.

[0128] Rebuild The reconstruction unit 214 (for example, an adder or summer 214) is configured to obtain the reconstructed block 215 in the sample region by adding the transformed block 213 (i.e., the reconstructed residual block 213) to the predicted block 265 by adding the sample values ​​of the reconstructed residual block 213 and the sample values ​​of the predicted block 265 --sample by sample.

[0129] filtering The loop filter unit 220 (or simply "loop filter" 220) is configured to filter the reconstructed block 215 to obtain the filtered block 221, or more generally, to filter the reconstructed sample to obtain the filtered sample value. The loop filter unit is configured, for example, to smooth pixel transitions or otherwise improve the quality of the video. The loop filter unit 220 may include one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or one or more other filters, such as an adaptive loop filter (ALF), a noise suppression filter (NSF), or any combination thereof. In the example, the loop filter unit 220 may include a deblocking filter, an SAO filter, and an ALF filter. The order of the filtering process may be deblocking filter, SAO, and ALF. In another example, a process called luma mapping with chroma scaling (LMCS) (i.e., an adaptive in-loop reshaper) is added. This process is performed before deblocking. In yet another example, the deblocking filter process may also be applied to the edges of internal subblocks, such as the edges of affine subblocks, ATMVP subblocks, sub-block transform (SBT) edges, and intra-sub-partition (ISP) edges. The loop filter unit 220 is shown in Figure 2 as an in-loop filter, but in other configurations, the loop filter unit 220 may be implemented as a post-loop filter. The filtered block 221 may also be called the filtered reconstructed block 221.

[0130] Embodiments of the video encoder 20 (each a loop filter unit 220) may be configured to output loop filter parameters (such as SAO filter parameters, or ALF filter parameters (ALF parameters), or LMCS parameters) which are either left as they are or encoded by the entropy coding unit 270, so that a decoder 30 may receive the same loop filter parameters or the respective loop filters and apply them for decoding. Here, the entropy coding unit 270 may encode a picture-level syntax element into the picture header of the current picture, which is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture.

[0131] Decode picture buffer The decoded picture buffer (DPB) 230 may be a memory that stores a reference picture or generally reference picture data for encoding video data by the video encoder 20. The DPB 230 may be formed by one of various memory devices, such as dynamic random access memory (DRAM) including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The decoded picture buffer (DPB) 230 may be configured to store one or more filtered blocks 221. The decoded picture buffer 230 may be further configured to store the same current picture or a different picture, for example, other already filtered blocks of an already reconstructed picture, for example, an already reconstructed and filtered block 221, for example, to provide a complete already reconstructed, i.e., decoded picture (and corresponding reference blocks and samples) and / or a partially reconstructed current picture (and corresponding reference blocks and samples) for interpretation. The decoded picture buffer (DPB) 230 may also be configured to store, for example, one or more unfiltered reconstructed blocks 215 or generally unfiltered reconstructed samples if the reconstructed blocks 215 are not filtered by the loop filter unit 220, or to store any other further processed versions of the reconstructed blocks or samples.

[0132] Mode Selection (Classification & Prediction) The mode selection unit 260 includes a partitioning unit 262, an inter-prediction unit 244, and an intra-prediction unit 254, and is configured to receive or acquire original picture data, for example, the original block 203 (the current block 203 of the current picture 17), and reconstructed picture data, for example, filtered and / or unfiltered reconstructed samples or blocks from one or more already decoded pictures of the same (current) picture and / or from, for example, the decoded picture buffer 230 or other buffers (for example, line buffers not shown). The reconstructed picture data is used as reference picture data for predictions, for example, inter-prediction or intra-prediction, to acquire prediction blocks 265 or predictor 265.

[0133] The mode selection unit 260 may be configured to determine or select a partitioning and prediction mode (e.g., intra or inter-prediction mode) for the prediction mode of the current block (without partitioning), and to generate a corresponding prediction block 265 used for calculating the residual block 205 and reconstructing the reconstructed block 215.

[0134] Embodiments of the mode selection unit 260 may be configured to select a partitioning and prediction mode (for example, from partitioning and prediction modes supported by or available to the mode selection unit 260) that provides the best match or, in other words, the smallest residual (smallest residual means better compression for transmission or storage) or the smallest signaling overhead (smallest signaling overhead means better compression for transmission or storage), or that considers both or balances them. The mode selection unit 260 may be configured to determine the partitioning and prediction mode based on rate distortion optimization (RDO), i.e., to select a prediction mode that provides the smallest rate distortion. In this context, terms such as “best,” “smallest,” and “optimal” do not necessarily refer to the overall “best,” “smallest,” and “optimal,” and may also refer to termination or selection criteria such as a value being above or below a threshold, or potentially leading to a “suboptimal choice,” but satisfying other constraints that reduce complexity and processing time.

[0135] In other words, the partitioning unit 262 may be configured to partition the pictures of the video sequence into a sequence of coding tree units (CTUs), the CTUs 203 may be further partitioned into smaller block partitions or subblocks (forming blocks again) using, for example, quadtree partitioning (QT), binary partitioning (BT), or ternary partitioning (TT), or any combination thereof, iteratively, the partitioning unit 262 may be configured to perform predictions with respect to each of the block partitions or subblocks, the mode selection includes selecting the tree structure of the partitioned block 203, and the prediction mode is applied to each of the block partitions or subblocks.

[0136] The following describes in more detail the sorting (by the sorting unit 260, for example) and prediction (by the inter-prediction unit 244 and intra-prediction unit 254) processes performed by the exemplary video encoder 20.

[0137] classification The partitioning unit 262 may be configured to partition the pictures of a video sequence into a sequence of coding tree units (CTUs), which may partition (or divide) the coding tree units (CTUs) 203 into smaller sections, for example, smaller blocks of square or rectangular size. For a picture with three sample sequences, the CTU consists of an N×N block of luma samples and two corresponding blocks of chroma samples. The maximum allowable size of the luma block in a CTU is specified as 128×128 in the Multipurpose Video Coding (VVC) under development, but may be specified as a larger value than 128×128 in the future, for example, 256×256. The CTUs of a picture may be clustered / grouped as slice / tile groups, tiles, or bricks. A tile encompasses a rectangular area of ​​a picture, and a tile may be divided into one or more bricks. A brick consists of several rows of CTUs within a tile. A tile that is not divided into multiple bricks may be called a brick. However, a brick is a pure subset of a tile and is not called a tile. There are two modes of tile groups supported in VVC: raster scan slice / tile group mode and rectangular slice mode. In raster scan tile group mode, a slice / tile group contains a sequence of tiles from the raster scan of the tiles of a picture. In rectangular slice mode, a slice contains several bricks of a picture that collectively form a rectangular area of ​​the picture. The bricks within a rectangular slice are in the order of the raster scan of the bricks in the slice. These smaller blocks (which may also be called subblocks) may be further divided into even smaller sections.This is also called tree partitioning or hierarchical tree partitioning. For example, the root block at root tree level 0 (hierarchy level 0, depth 0) may be recursively partitioned into, for example, two or more blocks at the next lowest tree level, for example, nodes at tree level 1 (hierarchy level 1, depth 1), and these blocks may be further partitioned into, for example, two or more blocks at the next lowest level, for example, tree level 2 (hierarchy level 2, depth 2), and so on until a termination criterion is met, for example, the maximum tree depth or the minimum block size is reached and partitioning ends. Blocks that are not further partitioned are also called leaf blocks or leaf nodes. A tree that uses partitioning into two sections is called a binary tree (BT), a tree that uses partitioning into three sections is called a ternary tree (TT), and a tree that uses partitioning into four sections is called a quadary tree (QT).

[0138] For example, a coding tree unit (CTU) could be or include a CTB of a luminous sample, two corresponding CTBs of a chroma sample of a picture having three sample sequences, or a CTB of a sample of a picture coded using three separate color planes and syntax structures used to code a monochrome picture or sample. Correspondingly, a coding tree block (CTB) could be an N×N block of samples for some value of N such that the division of its components into CTBs is a partition. A coding unit (CU) could be a coding block of a luminous sample, two corresponding coding blocks of a chroma sample of a picture having three sample sequences, or a coding block of a sample of a picture coded using three separate color planes and syntax structures used to code a monochrome picture or sample. Correspondingly, a coding block (CB) could be an M×N block of samples for some values ​​of M and N such that the division of a CTB into a coding block is a partition.

[0139] For example, in an embodiment using HEVC, a coding tree unit (CTU) may be partitioned into CUs by using a quadtree structure that is represented as a coding tree. The decision of whether to code a picture area using interpicture (time) prediction or intrapicture (spatial) prediction is made at the leaf CU level. Each leaf CU may be further partitioned into one, two, or four PUs according to the PU partitioning type. Within a single PU, the same prediction process is applied, and relevant information is sent to the decoder based on the PU. After obtaining residual blocks by applying the prediction process based on the PU partitioning type, the leaf CU may be partitioned into transformation units (TUs) by another quadtree structure similar to a coding tree with respect to the CU.

[0140] For example, in an embodiment of the latest video coding standard currently under development called Multipurpose Video Coding (VVC), a nested multitype tree of combined quadtrees using, for example, bipartite and tripartite segmentation structures is used to partition coding tree units. In the coding tree structure within a coding tree unit, the CU can have either a square or rectangular shape. For example, a coding tree unit (CTU) is first partitioned by a quadtree. Then, the leaf nodes of the quadtree can be further partitioned by a multitype tree structure. There are four partition types in the multitype tree structure: vertical bipartite (SPLIT_BT_VER), horizontal bipartite (SPLIT_BT_HOR), vertical tripartite (SPLIT_TT_VER), and horizontal tripartite (SPLIT_TT_HOR). The leaf nodes of the multitype tree are called coding units (CUs), and this segmentation is used for prediction and transformation processing without any further partitioning, as long as the CU is not too long with respect to the maximum transform length. This means that, in most cases, the CU, PU, ​​and TU have the same block size within a quadtree with a nested multi-type tree coding block structure. Exceptions occur when the maximum supported transformation length is smaller than the width or height of the CU's color components. VVC develops a unique signaling mechanism for partitioning information within a quadtree with a nested multi-type tree coding tree structure. In the signaling mechanism, the coding tree unit (CTU) is treated as the root of the quadtree and is initially partitioned by the quadtree structure. Each leaf node of the quadtree (when large enough to allow it) is further partitioned by the multi-type tree structure.In a multi-type tree structure, a first flag (mtt_split_cu_flag) is signaled to indicate whether a node is further subdivided, and if so, a second flag (mtt_split_cu_vertical_flag) is signaled to indicate the subdivision direction, and then a third flag (mtt_split_cu_binary_flag) is signaled to indicate whether the subdivision is bipartite or tripartite. Based on the values ​​of mtt_split_cu_vertical_flag and mtt_split_cu_binary_flag, the CU's multi-type tree subdivision mode (MttSplitMode) can be derived by the decoder based on a predefined rule or table. Note that for specific designs, such as the 64x64 lumar block and 32x32 chroma pipeline designs of the VVC hardware decoder, TT subdivision is prohibited when either the width or height of the lumar coding block is greater than 64, as shown in Figure 6. TT partitioning is also prohibited if either the width or height of the chromacoding block is greater than 32. The pipeline design divides the picture into virtual pipeline data units (VPDUs), which are defined as non-overlapping units within the picture. In hardware decoders, sequential VPDUs are processed simultaneously by multiple pipeline stages. The size of the VPDU is roughly proportional to the buffer size of most pipeline stages, and therefore it is important to keep the VPDU size small. In most hardware decoders, the VPDU size can be set to the maximum translation block (TB) size. However, in VVCs, ternary (TT) and binary (BT) partitioning can lead to an increase in VPDU size.

[0141] Furthermore, when part of a tree node block crosses the lower or right picture boundary, the tree node block is forced to split until all samples of any coded CU are within the picture boundary.

[0142] For example, the Intra Subpartitioning (ISP) tool might divide Luma's predicted intra-block into two or four subpartitions vertically or horizontally, depending on the block size.

[0143] In one example, the mode selection unit 260 of the video encoder 20 may be configured to perform any combination of the classification techniques described herein.

[0144] As described above, the video encoder 20 is configured to determine or select the best or optimal prediction mode from a set of (for example, predetermined) prediction modes. The set of prediction modes may include, for example, an intra-prediction mode and / or an inter-prediction mode.

[0145] Intra Prediction A set of intra-prediction modes may include, for example, 35 different intra-prediction modes defined in HEVC, such as DC (or average) mode and non-directional modes like planar mode, or directional modes, or for example, 67 different intra-prediction modes defined for VVC, such as DC (or average) mode and non-directional modes like planar mode, or directional modes. As an example, some normal angular intra-prediction modes are adaptively replaced by wide-angle intra-prediction modes for non-square blocks, as defined in VVC, for example. As another example, to avoid partitioning for DC prediction, only the long side is used to calculate the average with respect to non-square blocks. Also, the results of intra-prediction in planar mode may be further modified by the position-dependent intra-prediction combination (PDPC) method.

[0146] The intra-prediction unit 254 is configured to generate an intra-prediction block 265 using reconstructed samples of neighboring blocks of the same current picture, based on one of the intra-prediction modes in a set of intra-prediction modes.

[0147] The intra-prediction unit 254 (or generally the mode selection unit 260) is further configured to output intra-prediction parameters (or generally information indicating a selected intra-prediction mode for a block) to the entropy coding unit 270 in the form of syntax elements 266 for inclusion in the encoded picture data 21, for example, so that the video decoder 30 may receive the prediction parameters and use them for decoding.

[0148] Interpretation A set of (or possible) interpretation modes depends on the available reference picture (i.e., a previously at least partially decoded picture stored in DBP230) and other interpretation parameters, such as whether the entire reference picture is used to search for the best-matching reference block, or only a portion of the reference picture, such as only the search window area around the current block, and / or whether pixel interpolation, such as half / semi-pel, quarter-pel, and / or sixteenth-pel interpolation, is applied.

[0149] In addition to the prediction modes described above, skip mode, direct mode, and / or other interpretation modes may be applied.

[0150] For example, in an extended merge prediction, the merge candidate list for such a mode is constructed by including, in order, the following five types of candidates: spatial MVP from spatially neighboring CUs, temporal MVP from CUs in the same location, history-based MVP from the FIFO table, average MVP of the pair, and zero MV. Decoder-side motion vector refinement (DMVR) based on bidirectional matching may also be applied to improve the accuracy of the MV in the merge mode. Merge mode with MVD (MMVD) is derived from the merge mode using the difference in motion vectors. The MMVD flag is signaled immediately after the skip flag and merge flag are sent to specify whether the MMVD mode is used for the CU. Adaptive motion vector resolution (AMVR) schemes at the CU level may also be applied. AMVR allows the MVD of a CU to be coded with different accuracies. Depending on the prediction mode for the current CU, the MVD of the current CU may be adaptively selected. When a CU is coded in merge mode, the combined inter / intra prediction (CIIP) mode may be applied to the current CU. A weighted average of the inter and intra prediction signals is performed to obtain the CIIP prediction. In affine motion compensation prediction, the affine motion field of a block is described by motion information of two control points (4 parameters) or three control point motion vectors (6 parameters). Subblock-based temporal motion vector prediction (SbTMVP) is similar to HEVC's temporal motion vector prediction (TMVP), but predicts the motion vector of the subblock within the current CU.Bidirectional Optical Flow (BDOF), formerly known as BIO, is a simpler version requiring significantly fewer calculations, particularly in terms of the number of multiplications and the size of the multiplier. Regarding the triangular partitioning mode, in such a mode, the CU is evenly divided into two triangular partitions using either diagonal or opposite-angle partitioning. Furthermore, the bi-prediction mode extends from simple averaging to allow for a weighted average of two prediction signals.

[0151] The interpretation unit 244 may include a motion estimation (ME) unit and a motion compensation (MC) unit (neither of which are shown in Figure 2). The motion estimation unit may be configured to receive or acquire, for motion estimation, picture block 203 (the current picture block 203 of the current picture 17) and decoded picture 231, or at least one or more already reconstructed blocks, for example, one or more other / different reconstructed blocks of already decoded picture 231. For example, a video sequence may include the current picture and already decoded picture 231, or in other words, the current picture and already decoded picture 231 may be part of a sequence of pictures that make up the video sequence or may make up a sequence of such pictures.

[0152] The encoder 20 may be configured, for example, to select a reference block from multiple reference blocks of the same or different pictures among several other pictures, and to provide the motion estimation unit with an offset (spatial offset) between the reference picture (or reference picture index) and / or the position (x, y coordinates) of the reference block and the position of the current block as an interpretation parameter. This offset is also called the motion vector (MV).

[0153] The motion compensation unit is configured to obtain interprediction parameters, for example, receive them, and perform interprediction based on or using the interprediction parameters to obtain interprediction block 265. Motion compensation performed by the motion compensation unit may include fetching or generating prediction blocks based on motion / block vectors determined by motion estimation, possibly performing subpixel-precision interpolation. Interpolation filtering may generate additional pixel samples from known pixel samples, and thus potentially increase the number of candidate prediction blocks that can be used to code picture blocks. Upon receiving a motion vector about the current picture block's PU, the motion compensation unit may find the prediction block pointed to by the motion vector in one of the reference picture lists.

[0154] The motion compensation unit may also generate block and video slice-related syntax elements for use by the video decoder 30 when decoding the picture blocks of the video slice. In addition to slices and their respective syntax elements, or as an alternative to slices and their respective syntax elements, tile groups and / or tiles and their respective syntax elements may be generated or used.

[0155] Entropy coding The entropy coding unit 270 is configured to apply, for example, an entropy coding algorithm or scheme (e.g., variable length coding (VLC) scheme, context adaptive VLC (CAVLC) scheme, arithmetic coding scheme, binarization, context adaptive binary arithmetic coding (CABAC) scheme, syntax-based context-adaptive binary arithmetic coding (SBAC) scheme, probability interval partitioning entropy (PIPE) coding, or another entropy coding method or technique) or bypass (uncompressed) to quantized coefficients 209, inter-prediction parameters, intra-prediction parameters, loop filter parameters (such as a set of ALF parameters), and / or other syntax elements, for example, to obtain encoded picture data 21 that can be output via output 272 in the form of an encoded bitstream 21, for example, so that the video decoder 30 may receive the parameters and use them for decoding. The encoded bitstream 21 may be sent to the video decoder 30 or stored in memory for later transmission or retrieval by the video decoder 30.

[0156] Other variations of the video encoder 20 and other structures may be used to encode a video stream. For example, a non-transformation encoder 20 may directly quantize the residual signal with respect to a particular block or frame without a transformation processing unit 206. In another implementation, the encoder 20 may have a quantization unit 208 and an inverse quantization unit 210 combined into a single unit.

[0157] Decoder and decoding method Figure 3 shows an example of a video decoder 30 configured to implement the technology of the present application. The video decoder 30 is configured to receive encoded picture data 21 (e.g., encoded bitstream 21) encoded by, for example, the encoder 20, in order to obtain a decoded picture 331. The encoded picture data or bitstream contains information for decoding the encoded picture data, for example, the picture blocks of the encoded video slice (and / or tile group or tile) and the associated syntax elements.

[0158] In the example in Figure 3, the decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transformation processing unit 312, a reconstruction unit 314 (e.g., an aggregater 314), a loop filter 320, a decoded picture buffer (DBP) 330, a mode application unit 360, an interpretation unit 344, and an intraprediction unit 354. The interpretation unit 344 may be a motion compensation unit or may include a motion compensation unit. In some examples, the video decoder 30 may perform a decoding path that is generally the reverse of the encoding path described in relation to the video encoder 100 in Figure 2.

[0159] As described in relation to encoder 20, the inverse quantization unit 210, inverse processing unit 212, reconstruction unit 214, loop filter 220, decoding picture buffer (DPB) 230, inter-prediction unit 344, and intra-prediction unit 354 can also be considered to form the “built-in decoder” of video encoder 20. Thus, the inverse quantization unit 310 may be functionally identical to the inverse quantization unit 110, the inverse processing unit 312 may be functionally identical to the inverse processing unit 212, the reconstruction unit 314 may be functionally identical to the reconstruction unit 214, the loop filter 320 may be functionally identical to the loop filter 220, and the decoding picture buffer 330 may be functionally identical to the decoding picture buffer 230. Therefore, the descriptions given for each unit and function of video encoder 20 apply mutatis mutandis to each unit and function of video decoder 30.

[0160] Entropy decoding The entropy decoding unit 304 is configured to analyze the bitstream 21 (or generally the encoded picture data 21) and, for example, perform entropy decoding on the encoded picture data 21 to obtain, for example, quantized coefficients 309 and / or decoded coding parameters (not shown in Figure 3), such as inter-prediction parameters (e.g., reference picture index and motion vector), intra-prediction parameters (e.g., intra-prediction mode or index), transformation parameters, quantization parameters, loop filter parameters, and / or other syntax elements. The entropy decoding unit 304 may be configured to apply a decoding algorithm or scheme corresponding to the encoding scheme described in relation to the entropy coding unit 270 of the encoder 20. The entropy decoding unit 304 may be further configured to provide the inter-prediction parameters, intra-prediction parameters, and / or other syntax elements to the mode application unit 360 and other parameters to other units of the decoder 30. The video decoder 30 may receive syntax elements at the video slice level and / or video block level. In addition to slices and their respective syntax elements, or as an alternative to slices and their respective syntax elements, tile groups and / or tiles and their respective syntax elements may be received and / or used.

[0161] inverse quantization The inverse quantization unit 310 may be configured to receive quantization parameters (QP) (or information generally related to inverse quantization) and quantized coefficients from the encoded picture data 21 (for example, by the entropy decoding unit 304, for example, by parsing and / or decoding), and to apply inverse quantization to the decoded quantized coefficients 309 based on the quantization parameters to obtain dequantized coefficients 311, which may also be called transformed coefficients 311. The inverse quantization process may include using the quantization parameters determined by the video encoder 20 for each video block in the video slice (or tile or tile group) to determine the degree of quantization and, similarly, the degree of inverse quantization to be applied.

[0162] Inverse Transform The inverse transformation processing unit 312 may be configured to receive the dequantized coefficients 311, also called the transformation coefficients 311, and to apply a transformation to the dequantized coefficients 311 in order to obtain the reconstructed residual block 213 in the sample region. The reconstructed residual block 213 may also be called the transformation block 213. The transformation may be an inverse transformation, such as an inverse DCT, inverse DST, inverse integer transformation, or a conceptually similar inverse transformation process. The inverse transformation processing unit 312 may be further configured to receive transformation parameters or corresponding information from the encoded picture data 21 (for example, by parsing and / or decoding by the entropy decoding unit 304) in order to determine the transformation to be applied to the dequantized coefficients 311.

[0163] Rebuild The reconstruction unit 314 (for example, an adder or summer 314) may be configured to obtain the reconstructed block 315 in the sample region by adding the reconstructed residual block 313 to the predicted block 365, for example, by adding the sample values ​​of the reconstructed residual block 313 to the sample values ​​of the predicted block 365.

[0164] filtering The loop filter unit 320 (either within or after the coding loop) is configured to filter the reconstructed block 315 to smooth pixel transitions or otherwise improve video quality, for example, to obtain the filtered block 321. The loop filter unit 320 may include one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or one or more other filters, such as an adaptive loop filter (ALF), a noise suppression filter (NSF), or any combination thereof. In the example, the loop filter unit 220 may include a deblocking filter, an SAO filter, and an ALF filter. The order of the filtering process may be deblocking filter, SAO, and ALF. In another example, a process called lumamapping with chroma scaling (LMCS) (i.e., an adaptive in-loop reshaper) is added. This process is performed before deblocking. In another example, the deblocking filter process may also be applied to the edges of internal lower blocks, such as the edges of affine lower blocks, ATMVP lower blocks, lower block transform (SBT) edges, and intra-sub-partition (ISP) edges. The loop filter unit 320 is shown in Figure 3 as an in-loop filter, but in other configurations, the loop filter unit 320 may be implemented as a post-loop filter.

[0165] Decode picture buffer The decoded video block 321 of the picture is then stored in a decoded picture buffer 330, which stores the decoded picture 331 for use as a reference picture for subsequent motion compensation for other pictures and / or for output on the display, respectively.

[0166] The decoder 30 is configured to output the decoded picture 311, for example, via output 312, for presentation or viewing to the user.

[0167] prediction The inter-prediction unit 344 may be identical to the inter-prediction unit 244 (particularly the motion compensation unit), and the intra-prediction unit 354 may be functionally identical to the inter-prediction unit 254, and perform partitioning or partitioning decisions and predictions based on partitioning and / or prediction parameters or their respective information received from the decoded picture data 21 (for example, by analysis and / or decoding by the entropy decoding unit 304). The mode application unit 360 may be configured to perform block-by-block predictions (intra or inter-predictions) based on the reconstructed picture, block, or their respective samples (filtered or unfiltered) in order to obtain prediction blocks 365.

[0168] When a video slice is coded as an intra-coded (I) slice, the intra-prediction unit 354 of the mode application unit 360 is configured to generate a prediction block 365 for the picture block of the current video slice based on the signaled intra-prediction mode and data from already decoded blocks of the current picture. When a video picture is coded as an inter-coded (i.e., B or P) slice, the inter-prediction unit 344 (e.g., motion compensation unit) of the mode application unit 360 is configured to generate a prediction block 365 for the video block of the current video slice based on motion vectors and other syntax elements received from the entropy decoding unit 304. With respect to inter-prediction, the prediction block may be generated from one of the reference pictures in one of the reference picture lists. The video decoder 30 may construct reference frame lists, List 0 and List 1, using default construction techniques based on the reference pictures stored in the DPB 330. The same or similar may apply to or by embodiments that use tile groups (e.g., video tile groups) and / or tiles (e.g., video tiles) in addition to or as a substitute for slices (e.g., video slices), for example, video may be coded using I, P, or B tile groups and / or tiles.

[0169] The mode-applying unit 360 is configured to determine predictive information about the video blocks of the current video slice by analyzing motion vectors or related information and other syntax elements, and to use the predictive information to generate a predictive block about the current video block being decoded. For example, the mode-applying unit 360 uses some of the received syntax elements to determine the predictive mode used to code the video blocks of the video slice (e.g., intra or inter predictive), the slice type of inter predictive (e.g., B slice, P slice, or GPB slice), construction information about one or more of the reference picture lists for the slice, motion vectors for each intercoded video block of the slice, the status of the inter predictive for each intercoded video block of the slice, and other information for decoding the video blocks in the current video slice. The same or similar may apply for or by embodiments that use tile groups (e.g., video tile groups) and / or tiles (e.g., video tiles) in addition to or as an alternative to slices (e.g., video slices), for example, video may be coded using I, P, or B tile groups and / or tiles.

[0170] Embodiments of the video decoder 30 shown in Figure 3 may be configured to partition and / or decode a picture by using slices (also called video slices), the picture may be partitioned into one or more (generally non-overlapping) slices or decoded using one or more (generally non-overlapping) slices, each slice may contain one or more blocks (e.g., CTUs) or one or more groups of blocks (e.g., tiles (H.265 / HEVC and VVC) or bricks (VVC)).

[0171] Embodiments of the video decoder 30 shown in Figure 3 may be configured to segment and / or decode a picture by using slice / tile groups (also called video tile groups) and / or tiles (also called video tiles), the picture may be segmented into one or more (generally non-overlapping) slice / tile groups or decoded using one or more (generally non-overlapping) slice / tile groups, each slice / tile group may, for example, contain one or more blocks (e.g., CTUs) or one or more tiles, each tile may, for example, be rectangular in shape and may contain one or more blocks (e.g., CTUs), for example, complete or fragmented blocks.

[0172] Other variations of the video decoder 30 may be used to decode the encoded picture data 21. For example, the decoder 30 may generate an output video stream without a loop filtering unit 320. For example, a non-transformation-based decoder 30 may directly dequantize the residual signal with respect to a particular block or frame without an inverse transformation processing unit 312. In another implementation, the video decoder 30 may have an inverse quantization unit 310 and an inverse transformation processing unit 312 combined into a single unit.

[0173] It should be understood that in encoder 20 and decoder 30, the processing result of the current step may be further processed and then output to the next step. For example, after interpolation filtering, motion vector derivation, or loop filtering, further operations such as clipping or shifting may be performed on the processing result of interpolation filtering, motion vector derivation, or loop filtering.

[0174] Note that further calculations may be applied to the derived motion vector of the current block (including, but not limited to, affine mode control point motion vectors, affine, planar, and ATMVP mode lower block motion vectors, and temporal motion vectors). For example, the value of a motion vector is constrained to a given range according to its representation bits. If the representation bits of a motion vector are bitDepth, the range is -2^(bitDepth-1) to 2^(bitDepth-1)-1, where "^" means exponentiation. For example, if bitDepth is set to be equal to 16, the range is -32768 to 32767, and if bitDepth is set to be equal to 18, the range is -131072 to 131071. For example, the values ​​of the derived motion vectors (e.g., the MVs of four 4x4 subblocks within one 8x8 block) are constrained such that the maximum difference between the integer parts of the MVs of the four 4x4 subblocks is less than or equal to N pixels, such as less than or equal to 1 pixel. Here, we provide two methods for constraining motion vectors according to bitDepth.

[0175] Figure 4 is a schematic diagram of a video coding device 400 according to an embodiment of the present disclosure. The video coding device 400 is suitable for implementing embodiments disclosed as described herein. In embodiments, the video coding device 400 may be a decoder, such as the video decoder 30 in Figure 1A, or an encoder, such as the video encoder 20 in Figure 1A.

[0176] The video coding device 400 includes an incoming port 410 (or input port 410) and a receiver unit (Rx) 420 for receiving data, a processor, logic unit, or central processing unit (CPU) 430 for processing data, a transmitter unit (Tx) 440 and an outgoing port 450 (or output port 450) for transmitting data, and memory 460 for storing data. The video coding device 400 may also include optical-electrical (OE) and electrical-optical (EO) components coupled to the incoming port 410, receiver unit 420, transmitter unit 440, and outgoing port 450 for transmitting or receiving optical or electrical signals.

[0177] The processor 430 is implemented by hardware and software. The processor 430 may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), FPGAs, ASICs, and DSPs. The processor 430 communicates with the incoming port 410, the receiver unit 420, the transmitter unit 440, the outgoing port 450, and the memory 460. The processor 430 includes a coding module 470. The coding module 470 implements the embodiments disclosed above. For example, the coding module 470 implements, processes, prepares, or provides various coding operations. Thus, including the coding module 470 greatly improves the functionality of the video coding device 400 and results in the transition of the video coding device 400 to different states. Alternatively, the coding module 470 is implemented as instructions stored in the memory 460 and executed by the processor 430.

[0178] Memory 460 may include one or more disks, tape drives, and solid-state drives and may be used as an over-flow data storage device to store such programs when selected to run, as well as instructions and data read during program execution. Memory 460 may be, for example, volatile and / or non-volatile, and may be read-only memory (ROM), random-access memory (RAM), ternary content-addressable memory (TCAM), and / or static random-access memory (SRAM).

[0179] Figure 5 is a simplified block diagram of a device 500 that may be used as either or both of the source device 12 and destination device 14 in Figure 1, according to an exemplary embodiment.

[0180] The processor 502 of the device 500 can be a central processing unit. Alternatively, the processor 502 can be one or more devices of any other type, existing or to be developed, capable of manipulating or processing information. The disclosed implementation can be carried out by a single processor, for example, processor 502, as shown, but speed and efficiency advantages can be realized by using two or more processors.

[0181] The memory 504 of the device 500 can be, in implementation, a read-only memory (ROM) device or a random access memory (RAM) device. Any other suitable type of storage device may be used as memory 504. Memory 504 may include code and data 506 accessed by the processor 502 using the bus 512. Memory 504 may further include an operating system 508 and an application program 510, the application program 510 including at least one program that enables the processor 502 to perform the methods described herein. For example, the application program 510 may include applications 1 to N, further including a video coding application that performs the methods described herein.

[0182] The apparatus 500 may also include one or more output devices, such as a display 518. In one example, the display 518 may be a touch display that combines the display with a touch-sensing element that is operable to sense touch input. The display 518 may be coupled to the processor 502 via a bus 512.

[0183] Although shown here as a single bus, the bus 512 of device 500 may consist of multiple buses. Furthermore, the secondary storage 514 can be directly coupled to other components of device 500 or accessed via a network, and may include a single integrated unit such as a memory card or multiple units such as multiple memory cards. Thus, device 500 can be implemented in a wide variety of configurations.

[0184] Decoder Parameter Set (DPS) A syntax structure is proposed to include a `profile_level()` syntax structure that indicates the maximum number of sublayers (similar to HEVC), the profiles and levels of decoders capable of decoding the bitstream, and constraints applied to the bitstream.

[0185] An example of a DPS syntax table is shown below.

[0186] [Table 1]

[0187] The DPS raw byte sequence payload (RBSP) is made available to the decryption process before being referenced and is contained in at least one AU whose TemporalId is equal to 0, or is provided by an external means. Note 1 -- The DPS NAL unit must be available to the decoding process (either in the bitstream or by external means) before it is referenced. However, the DPS RBSP contains information that is not necessary for the operation of the decoding process as defined in Sections 2 through 9 of this Specification.

[0188] `dps_decoding_parameter_set_id` identifies the DPS for reference by other syntax elements. The value of `dps_decoding_parameter_set_id` is greater than 0.

[0189] The value obtained by adding 1 to dps_max_sublayers_minus1 specifies the maximum number of temporal sublayers that may exist within each CVS layer referencing DPS. The value of dps_max_sublayers_minus1 is in the range of 0 to 6, including 0 and 6.

[0190] dps_reserved_zero_5bits is equal to 0 in bitstreams conforming to this version of this specification. Other values ​​for dps_reserved_zero_5bits are reserved for future use by ITU-T | ISO / IEC.

[0191] The value obtained by adding 1 to dps_num_ptls_minus1 specifies the number of profile_tier_level() syntax structures within DPS.

[0192] When there are two or more profile_tier_level() syntax structures within a DPS, bitstream conformance requires that each CVS in the bitstream conform to at least one of the profile_tier_level() syntax structures.

[0193] A dps_extension_flag value equal to 0 indicates that the dps_extension_data_flag syntax element does not exist within the DPS RBSP syntax structure. A dps_extension_flag value equal to 1 indicates that the dps_extension_data_flag syntax element exists within the DPS RBSP syntax structure.

[0194] dps_extension_data_flag may have any value. The presence and value of dps_extension_data_flag do not affect the decoder's compliance with the profile specified in Appendix A. Decoders conforming to this version of this specification ignore all dps_extension_data_flag syntax elements.

[0195] RBSP syntax for sequence parameter sets

[0196] [Table 2]

[0197] A sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that the profile_tier_level() syntax structure and the dpb_parameters() syntax structure may exist in the SPS, and that the general_hrd_parameters() syntax structure and the ols_hrd_parameters() syntax structure may also exist in the SPS. A sps_ptl_dpb_hrd_params_present_flag equal to 0 specifies that none of these four syntax structures exist in the SPS. The value of sps_ptl_dpb_hrd_params_present_flag is equal to vps_independent_layer_flag[ GeneralLayerIdx[ nuh_layer_id ] ].

[0198] If vps_independent_layer_flag[ GeneralLayerIdx[ nuh_layer_id ] ] is equal to 1, the variable MaxDecPicBuffMinus1 is set to equal to max_dec_pic_buffering_minus1[ sps_max_sublayers_minus1 ] of the dpb_parameters() syntax structure in the SPS. Otherwise, MaxDecPicBuffMinus1 is set to equal to max_dec_pic_buffering_minus1[ sps_max_sublayers_minus1 ] of the layer_nonoutput_dpb_params_idx[ GeneralLayerIdx[ nuh_layer_id ] ]th dpb_parameters() syntax structure in the VPS.

[0199] General profile, tier, and level syntax

[0200] [Table 3]

[0201] Overall profile, tier, and level semantics The `profile_tier_level()` syntax structure provides level information and, optionally, profile, tier, subprofile, and general constraint information.

[0202] When the `profile_tier_level()` syntax structure is included in a DPS, OlsInScope is an OLS that includes all layers of the entire bitstream that references the DPS. When the `profile_tier_level()` syntax structure is included in a VPS, OlsInScope is one or more OLSs specified by the VPS. When the `profile_tier_level()` syntax structure is included in an SPS, OlsInScope is an OLS that includes only the lowest layer among the layers that reference the SPS, and this lowest layer is an independent layer.

[0203] general_profile_idc indicates the profile to which OlsInScope conforms, as specified in Appendix A. The bitstream does not contain any general_profile_idc values ​​other than those specified in Appendix A. Other values ​​for general_profile_idc are reserved by ITU-T | ISO / IEC for future use.

[0204] general_tier_flag specifies the tier context for interpreting general_level_idc, as defined in Appendix A.

[0205] general_level_idc indicates the level to which OlsInScope conforms, as specified in Appendix A. The bitstream does not contain any general_level_idc values ​​other than those specified in Appendix A. Other values ​​for general_level_idc are reserved by ITU-T | ISO / IEC for future use. Note 1 -- A larger value for general_level_idc indicates a higher level. The maximum level signaled within the DPS for OlsInScope may be higher than the level signaled within the SPS for CVS included in OlsInScope. Note 2 -- When OlsInScope conforms to multiple profiles, general_profile_idc should indicate the profile that provides the preferred decoded result or preferred bitstream identification information, as determined by the encoder (not specified herein). Note 3 -- When the --profile_tier_level() syntax structure is included in the DPS and the CVS of OlsInScope conforms to different profiles, general_profile_idc and level_idc should indicate the profile and level of the decoder that can decode OlsInScope.

[0206] num_sub_profiles specifies the number of syntax elements in general_sub_profile_idc[i].

[0207] general_sub_profile_idc[i] represents the i-th interoperability metadata registered as defined by Rec. ITU-T T.35, the contents of which are not defined in this specification.

[0208] A sublayer_level_present_flag[i] equal to 1 indicates that level information exists within the profile_tier_level() syntax structure for the sublayer representation where TemporalId is equal to i. A sublayer_level_present_flag[i] equal to 0 indicates that level information does not exist within the profile_tier_level() syntax structure for the sublayer representation where TemporalId is equal to i.

[0209] ptl_alignment_zero_bit is equal to 0.

[0210] The semantics of the syntax element sublayer_level_idc[i] are the same as those of the syntax element general_level_idc, except for the provision for inferring non-current values, but it applies to sublayer representations where TemporalId is equal to i.

[0211] If it does not exist, the value of sublayer_level_idc[i] is inferred as follows: - It is inferred that sublayer_level_idc[ maxNumSubLayersMinus1 ] is equal to general_level_idc, which has the same profile_tier_level() structure. - (In descending order of i values) maxNumSubLayersMinus1 - including 1 and 0, for i from 1 to 0, it is inferred that sublayer_level_idc[i] is equal to sublayer_level_idc[i + 1].

[0212] RBSP syntax for picture headers

[0213] [Table 4]

[0214] A pic_alf_enabled_present_flag equal to 1 indicates that pic_alf_enabled_flag, pic_num_alf_aps_ids_luma, pic_alf_aps_id_luma[i], pic_alf_chroma_idc, and pic_alf_aps_id_chroma exist in the PH. A pic_alf_enabled_present_flag equal to 0 indicates that pic_alf_enabled_flag, pic_num_alf_aps_ids_luma, pic_alf_aps_id_luma[i], pic_alf_chroma_idc, and pic_alf_aps_id_chroma do not exist in the PH. When pic_alf_enabled_present_flag does not exist, it is inferred that pic_alf_enabled_present_flag is equal to 0.

[0215] A pic_alf_enabled_flag equal to 1 specifies that the adaptive loop filter may be enabled for all slices related to PH and applied to the Y, Cb, or Cr color components within the slice. A pic_alf_enabled_flag equal to 0 specifies that the adaptive loop filter may be disabled for one, more, or all slices related to PH. If not present, pic_alf_enabled_flag is presumed to be equal to 0.

[0216] pic_num_alf_aps_ids_luma specifies the number of ALF APS referenced by the slice associated with the PH.

[0217] pic_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS referenced by the luma component of the slice associated with the PH.

[0218] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_luma[i], the value of alf_luma_filter_signal_flag is equal to 1.

[0219] A pic_alf_chroma_idc equal to 0 indicates that the adaptive loop filter is not applied to the Cb and Cr color components. A pic_alf_chroma_idc equal to 1 indicates that the adaptive loop filter is applied to the Cb color component. A pic_alf_chroma_idc equal to 2 indicates that the adaptive loop filter is applied to the Cr color component. A pic_alf_chroma_idc equal to 3 indicates that the adaptive loop filter is applied to both the Cb and Cr color components. When pic_alf_chroma_idc does not exist, it is inferred to be equal to 0.

[0220] pic_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS referenced by the chroma component of the PH-related slice.

[0221] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_chroma, the value of alf_chroma_filter_signal_flag is equal to 1.

[0222] PPS

[0223] [Table 5A] [Table 5B]

[0224] A pps_subpic_id_signalling_present_flag equal to 1 indicates that the subpicture ID mapping is signaled within the PPS. A pps_subpic_id_signalling_present_flag equal to 0 indicates that the subpicture ID mapping is not signaled within the PPS. When sps_subpic_id_present_flag is 0 or sps_subpic_id_signalling_present_flag is equal to 1, pps_subpic_id_signalling_present_flag is equal to 0.

[0225] The value obtained by adding 1 to pps_num_subpics_minus1 specifies the number of subpictures in the coded picture that references the PPS.

[0226] A requirement for bitstream compliance is that the value of pps_num_subpic_minus1 is equal to sps_num_subpics_minus1.

[0227] The value obtained by adding 1 to pps_subpic_id_len_minus1 specifies the number of bits used to represent the syntax element pps_subpic_id[i]. The value of pps_subpic_id_len_minus1 is in the range of 0 to 15, including 0 and 15.

[0228] A bitstream compliance requirement is that the value of pps_subpic_id_len_minus1 be the same for all PPS referenced by coded pictures within the CLVS.

[0229] pps_subpic_id[i] specifies the subpicture ID of the i-th subpicture. The length of the pps_subpic_id[i] syntax element is pps_subpic_id_len_minus1 + 1 bits.

[0230] A no_pic_partition_flag equal to 1 specifies that no picture partitioning is applied to each picture that references a PPS. A no_pic_partition_flag equal to 0 specifies that each picture that references a PPS may be partitioned into two or more tiles or slices.

[0231] A bitstream compliance requirement is that the value of no_pic_partition_flag be the same for all PPS referenced by coded pictures within the CLVS.

[0232] A bitstream compliance requirement is that when the value of sps_num_subpics_minus1 + 1 is greater than 1, the value of no_pic_partition_flag is not equal to 1.

[0233] The value obtained by adding 5 to pps_log2_ctu_size_minus5 specifies the luma coding tree block size for each CTU. pps_log2_ctu_size_minus5 is equal to sps_log2_ctu_size_minus5.

[0234] The value of num_exp_tile_columns_minus1 plus 1 specifies the number of tile column widths that are explicitly provided. The value of num_exp_tile_columns_minus1 is in the range of 0 to PicWidthInCtbsY - 1, including 0 and PicWidthInCtbsY - 1. When no_pic_partition_flag is equal to 1, the value of num_exp_tile_columns_minus1 is presumed to be equal to 0.

[0235] The value of num_exp_tile_rows_minus1 plus 1 specifies the number of tile row heights that are explicitly provided. The value of num_exp_tile_rows_minus1 is in the range of 0 to PicHeightInCtbsY - 1, including 0 and PicHeightInCtbsY - 1. When no_pic_partition_flag is equal to 1, the value of num_tile_rows_minus1 is presumed to be equal to 0.

[0236] The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0237] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1.

[0238] A rect_slice_flag equal to 0 specifies that the tiles within each slice are in raster scan order and slice information is not signaled within the PPS. A rect_slice_flag equal to 1 specifies that the tiles within each slice cover the rectangular area of ​​the picture and slice information is signaled within the PPS. If it does not exist, rect_slice_flag is presumed to be equal to 1. When subpics_present_flag is equal to 1, the value of rect_slice_flag is equal to 1.

[0239] A single_slice_per_subpic_flag equal to 1 specifies that each subpict consists of only one rectangular slice. A single_slice_per_subpic_flag equal to 0 specifies that each subpict may consist of one or more rectangular slices. When subpics_present_flag is equal to 0, single_slice_per_subpic_flag is equal to 0. When single_slice_per_subpic_flag is equal to 1, num_slices_in_pic_minus1 is inferred to be equal to sps_num_subpics_minus1.

[0240] The value of num_slices_in_pic_minus1 plus 1 specifies the number of rectangular slices in each picture that references the PPS. The value of num_slices_in_pic_minus1 is in the range of 0 to MaxSlicesPerPicture - 1, including 0 and MaxSlicesPerPicture - 1, where MaxSlicesPerPicture is defined in Appendix A. When no_pic_partition_flag is equal to 1, the value of num_slices_in_pic_minus1 is presumed to be equal to 0.

[0241] A tile_idx_delta_present_flag equal to 0 indicates that the tile_idx_delta value does not exist in the PPS and all rectangular slices in the picture referencing the PPS are specified in raster order according to the process defined in Section 6.5.1. A tile_idx_delta_present_flag equal to 1 indicates that the tile_idx_delta value may exist in the PPS and all rectangular slices in the picture referencing the PPS are specified in the order indicated by the tile_idx_delta value.

[0242] The value of slice_width_in_tiles_minus1[i] plus 1 specifies the width of the i-th rectangular slice in units of tile columns. The value of slice_width_in_tiles_minus1[i] is within the range of 0 to NumTileColumns - 1, including 0 and NumTileColumns - 1. If it does not exist, the value of slice_width_in_tiles_minus1[i] is inferred as specified in Section 6.5.1.

[0243] The value of slice_height_in_tiles_minus1[i] plus 1 specifies the height of the i-th rectangular slice in units of tile rows. The value of slice_height_in_tiles_minus1[i] is in the range of 0 to NumTileRows - 1, including 0 and NumTileRows - 1. If it does not exist, the value of slice_height_in_tiles_minus1[i] is inferred as specified in Section 6.5.1.

[0244] The value of num_slices_in_tile_minus1[i] plus 1 specifies the number of slices in the current tile, if the i-th slice contains a subset of CTU rows from a single tile. The value of num_slices_in_tile_minus1[i] is in the range of 0 to RowHeight[tileY] - 1, including 0 and RowHeight[tileY] - 1, where tileY is the index of the tile row containing the i-th slice. If it does not exist, the value of num_slices_in_tile_minus1[i] is presumed to be equal to 0.

[0245] The value of slice_height_in_ctu_minus1[i] plus 1 specifies the height of the i-th rectangular slice in units of CTU rows, if the i-th slice contains a subset of CTU rows from a single tile. The value of slice_height_in_ctu_minus1[i] is in the range of 0 to RowHeight[tileY] - 1, including 0 and RowHeight[tileY] - 1, where tileY is the index of the tile row containing the i-th slice.

[0246] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If it does not exist, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0.

[0247] 6.5.1 CTB Raster Scan, Tile Scan, and Subpicture Scan Process The variable NumTileColumns, which specifies the number of tile columns, and ColWidth[i], a list of values ​​for i ranging from 0 to NumTileColumn - 1, including 0 and NumTileColumn - 1, which specifies the width of the i-th tile column in units of CTB, are derived as follows: remainingWidthInCtbsY = PicWidthInCtbsY for( i = 0; i < num_exp_tile_columns_minus1; i++ ) { colWidth[ i ] = tile_column_width_minus1[ i ] + 1 remainingWidthInCtbsY -= colWidth[ i ] } uniformTileColWidth = tile_column_width_minus1[ num_exp_tile_columns_minus1 ] + 1 (23) while( remainingWidthInCtbsY >= uniformTileColWidth ) { colWidth[ i++ ] = uniformTileColWidth remainingWidthInCtbsY -= uniformTileColWidth } if( remainingWidthInCtbsY > 0 ) colWidth[ i++ ] = remainingWidthInCtbsY NumTileColumns = i

[0248] The variable NumTileRows, which specifies the number of tile rows, and RowHeight[j], a list for j ranging from 0 to NumTileRows - 1, including 0 and NumTileRows - 1, which specifies the height of the j-th tile row in units of CTB, are derived as follows: remainingHeightInCtbsY = PicHeightInCtbsY for( j = 0; j < num_exp_tile_rows_minus1; j++ ) { RowHeight[ j ] = tile_row_height_minus1[ j ] + 1 remainingHeightInCtbsY -= RowHeight[ j ] } uniformTileRowHeight = tile_row_height_minus1[ num_exp_tile_rows_minus1 ] + 1 (24) while( remainingHeightInCtbsY >= uniformTileRowHeight ) { RowHeight[ j++ ] = uniformTileRowHeight remainingHeightInCtbsY -= uniformTileRowHeight } if( remainingHeightInCtbsY > 0 ) RowHeight[ j++ ] = remainingHeightInCtbsY NumTileRows = j

[0249] The variable NumTilesInPic is set to be equal to NumTileColumns * NumTileRows.

[0250] The list tileColBd[i] for i in the range from 0 to NumTileColumns, including 0 and NumTileColumns, which specifies the boundary position of the i-th tile column in units of CTB, is derived as follows: for( tileColBd

[0000] = 0, i = 0; i < NumTileColumns; i++ ) tileColBd[ i + 1 ] = tileColBd[ i ] + colWidth[ i ] (25)

[0251] A list tileRowBd[ j ] for j in the range from 0 to NumTileRows, including 0 and NumTileRows, which specifies the position of the boundary of the j-th tile row in units of CTB, is derived as follows. for( tileRowBd

[0000] = 0, j = 0; j < NumTileRows; j++ ) tileRowBd[ j + 1 ] = tileRowBd[ j ] + RowHeight[ j ] (26)

[0252] A list CtbToTileColBd[ ctbAddrX ] for ctbAddrX in the range from 0 to PicWidthInCtbsY, including 0 and PicWidthInCtbsY, which specifies the conversion from the horizontal CTB address to the boundary of the left tile column in units of CTB, is derived as follows. tileX = 0 for( ctbAddrX = 0; ctbAddrX <= PicWidthInCtbsY; ctbAddrX++ ) { if( ctbAddrX == tileColBd[ tileX + 1 ] ) (27) tileX++ CtbToTileColBd[ ctbAddrX ] = tileColBd[ tileX ] }

[0253] A list CtbToTileRowBd[ ctbAddrY ] for ctbAddrY in the range from 0 to PicHeightInCtbsY, including 0 and PicHeightInCtbsY, which specifies the conversion from the vertical CTB address to the boundary of the upper tile row in units of CTB, is derived as follows. tileY = 0 for( ctbAddrY = 0; ctbAddrY <= PicHeightInCtbsY; ctbAddrY++ ) { if( ctbAddrY == tileRowBd[ tileY + 1 ] ) (28) tileY++ CtbToTileRowBd[ ctbAddrY ] = tileRowBd[ tileY ] } For rectangular slices, a list NumCtuInSlice[i] for i ranging from 0 to num_slices_in_pic_minus1, including 0 and num_slices_in_pic_minus1, which specifies the number of CTUs in the i-th slice, and a matrix CtbAddrInSlice[i][j] for i ranging from 0 to num_slices_in_pic_minus1, including 0 and num_slices_in_pic_minus1, and for j ranging from 0 to NumCtuInSlice[i]-1, including 0 and NumCtuInSlice[i]-1, are derived as follows: if( subpics_present_flag && single_slice_per_subpic_flag ) { for( i = 0; i <= sps_num_subpics_minus1; i++ ) NumCtuInSlice[i] = 0 for( i = 0; i < PicSizeInCtbsY; i ++ ) { sliceIdx = CtbToSubPicIdx[ i ] CtbAddrInSlice[ sliceIdx ][ NumCtuInSlice[ sliceIdx ] ] = i NumCtuInSlice[ sliceIdx ]++ } else { tileIdx = 0 for( i = 0; i <= num_slices_in_pic_minus1; i++ ) NumCtuInSlice[ i ] = 0 for( i = 0; i <= num_slices_in_pic_minus1; i++ ) { tileX = tileIdx % NumTileColumns tileY = tileIdx / NumTileColumns if( i == num_slices_in_pic_minus1 ) { slice_width_in_tiles_minus1[ i ] = NumTileColumns - 1 - tileX slice_height_in_tiles_minus1[ i ] = NumTileRows - 1 - tileY num_slices_in_tile_minus1[ i ] = 0 } if( slice_width_in_tiles_minus1[ i ] == 0 && slice_height_in_tiles_minus1[ i ] == 0 ) { (29) ctbY = tileRowBd[ tileY ] for( j = 0; j < num_slices_in_tile_minus1[ i ]; j++ ) { AddCtbsToSlice( i, tileColBd[ tileX ], tileColBd[ tileX + 1 ], ctbY, ctbY + slice_height_in_ctu_minus1[ i ] + 1 ) ctbY += slice_height_in_ctu_minus1[ i ] + 1 i++ } AddCtbsToSlice( i, tileColBd[ tileX ], tileColBd[ tileX + 1 ], ctbY, tileRowBd[ tileY + 1 ] ) ; } else for( j = 0; j <= slice_height_in_tiles_minus1[ i ]; j++ ); for( k = 0; k <= slice_width_in_tiles_minus1[ i ]; k++ ); AddCtbsToSlice( i, tileColBd[ tileX + k ], tileColBd[ tileX + k + 1 ], tileRowBd[ tileY + j ], tileRowBd[ tileY + j + 1 ] ) ; if( tile_idx_delta_present_flag ) tileIdx += tile_idx_delta[ i ] else { tileIdx += slice_width_in_tiles_minus1[ i ] + 1 if ( tileIdx % NumTileColumns == 0 ) ; tileIdx += slice_height_in_tiles_minus1[ i ] * NumTileColumns }} }} }}

[0254] The key AddCtbsToSlice( sliceIdx, startX, stopX, startY, stopY ) is one of these. for( ctbY = startY ; ctbY < stopY ; ctbY ++ ) ; for( ctbX = startX ; ctbX < stopX ; ctbX++ ) { ; CtbAddrInSlice[ sliceIdx ][ NumCtuInSlice[ sliceIdx ] ] = ctbY * PicWidthInCtbsY + ctbX (30) NumCtuInSlice[ sliceIdx ]++ }

[0255] It is a compliance requirement of the bitstream that the values of NumCtuInSlice[ i ] for i in the range from 0 to num_slices_in_pic_minus1, including 0 and num_slices_in_pic_minus1, be greater than 0. Further, it is a compliance requirement of the bitstream that the matrix CtbAddrInSlice[ i ][ j ] for i in the range from 0 to num_slices_in_pic_minus1, including 0 and num_slices_in_pic_minus1, and for j in the range from 0 to NumCtuInSlice[ i ] - 1, including 0 and NumCtuInSlice[ i ] - 1, contain all CTB addresses in the range from 0 to PicSizeInCtbsY - 1 only once.

[0256] The list CtbToSubPicIdx[ ctbAddrRs ] for ctbAddrRs in the range from 0 to PicSizeInCtbsY - 1, including 0 and PicSizeInCtbsY - 1, which specifies the conversion from CTB address to subpicture index in the picture raster scan, is derived as follows. for( ctbAddrRs = 0; ctbAddrRs < PicSizeInCtbsY; ctbAddrRs++ ) { posX = ctbAddrRs % PicWidthInCtbsY posY = ctbAddrRs / PicWidthInCtbsY CtbToSubPicIdx[ ctbAddrRs ] = -1 for( i = 0; CtbToSubPicIdx[ ctbAddrRs ] < 0 && i <= sps_num_subpics_minus1; i++ ) { (31) if( ( posX >= subpic_ctu_top_left_x[ i ] ) && ( posX < subpic_ctu_top_left_x[ i ] + subpic_width_minus1[ i ] + 1 ) && ( posY >= subpic_ctu_top_left_y[ i ] ) && ( posY < subpic_ctu_top_left_y[ i ] + subpic_height_minus1[ i ] + 1 ) ) CtbToSubPicIdx[ ctbAddrRs ] = i } }

[0257] The lists NumSlicesInSubpic[i] and SliceSubpicToPicIdx[i][k], which specify the number of rectangular slices in the i-th subpicture and the picture-level slice index of the k-th slice in the i-th subpicture, are derived as follows: for( j = 0; j <= sps_num_subpics_minus1; j++ ) NumSlicesInSubpic[ j ] = 0 for( i = 0; i <= num_slices_in_pic_minus1; i++ ) { posX = CtbAddrInSlice[ i ]

[0000] % PicWidthInCtbsY posY = CtbAddrInSlice[ i ]

[0000] / PicWidthInCtbsY for( j = 0; j <= sps_num_subpics_minus1; j++ ) { if( ( posX >= subpic_ctu_top_left_x[ j ] ) && (32) ( posX < subpic_ctu_top_left_x[ j ] + subpic_width_minus1[ j ] + 1 ) && ( posY >= subpic_ctu_top_left_y[ j ] ) && ( posY < subpic_ctu_top_left_y[ j ] + subpic_height_minus1[ j ] + 1 ) ) { SliceSubpicToPicIdx[ j ][ NumSlicesInSubpic[ j ] ] = i NumSlicesInSubpic[ j ]++ } } }

[0258] Currently, DPS units have a DPS ID, and there are no restrictions on the correspondence between the contents of a DPS NAL unit and its ID value.

[0259] Furthermore, there is no limit to the number of times a DPS can be present in a bitstream. If many DPS exist in the bitstream and they all have the same DPS ID, the decoder does not know which DPS to select.

[0260] The level signaled within DPS should be the worst-case capability of the entire bitstream, and therefore should not be lower than the level signaled within SPS.

[0261] Currently, there are no constraints on the TemporalId of an APS NAL unit or the TemporalId of a picture associated with a picture header (PH). However, when nal_unit_type is equal to PPS_NUT, PREFIX_APS_NUT, or SUFFIX_APS_NUT, the TemporalId must be greater than or equal to the TemporalId of the PU containing the NAL unit, and in bitstream subtraction scenarios, there should be constraints on the TemporalId of an APS NAL unit and the TemporalId of a picture associated with a PH.

[0262] The tile-relative variables tile_column_width_minus1[i], tile_row_height_minus1[i], and tile_idx_delta[i] should have some constraints applied to them to ensure appropriate values, since none of these variables for any tile can exceed the picture's boundaries. Additionally, the tile column and tile height should be greater than 0.

[0263] Embodiments: Option A: Add a constraint that a DPS can only exist at most once in a bitstream. In other words, a DPS is not required in a bitstream, and if a bitstream contains a DPS, only one DPS can exist in the bitstream.

[0264] The DPS RBSP becomes available to the decryption process before being referenced and is contained in at least one AU whose TemporalId is equal to 0, or is provided by an external means.

[0265] Note 1 -- A maximum of one DPS NAL unit exists within the bitstream.

[0266] Note 2 -- The DPS NAL unit must be available to the decoding process (either in the bitstream or by external means) before it is referenced. However, the DPS RBSP contains information that is not necessary for the operation of the decoding process as defined in Sections 2 through 9 of this Specification.

[0267] Option B: Add a constraint that all DPS NAL units with a specific value for dps_decoding_parameter_set_id in the bitstream have the same content. In this case, one DPS ID cannot hook (correspond) to the content of two or more DPS.

[0268] for example, The DPS RBSP becomes available to the decryption process before being referenced and is contained in at least one AU whose TemporalId is equal to 0, or is provided by an external means. Note 1 -- The DPS NAL unit must be available to the decoding process (either in the bitstream or by external means) before it is referenced. However, the DPS RBSP contains information that is not necessary for the operation of the decoding process as defined in Sections 2 through 9 of this Specification.

[0269] All DPS NAL units with a specific value for dps_decoding_parameter_set_id in the bitstream have the same content.

[0270] Add a constraint that the level signaled within DPS must be equal to or greater than the level signaled within SPS.

[0271] general_level_idc indicates the level to which OlsInScope conforms, as specified in Appendix A. The bitstream does not contain any general_level_idc values ​​other than those specified in Appendix A. Other values ​​for general_level_idc are reserved by ITU-T | ISO / IEC for future use. (1) Note 1 -- A larger value of general_level_idc indicates a higher level. The maximum level signaled within the DPS for OlsInScope is not less than the level signaled within the SPS for CVS included in OlsInScope. (2) Note 2 -- When OlsInScope conforms to multiple profiles, general_profile_idc should indicate the profile that provides the preferred decoded result or preferred bitstream identification information, as determined by the encoder (not specified herein). (3) Note 3 -- When the profile_tier_level() syntax structure is included in the DPS and the CVS of OlsInScope conforms to different profiles, general_profile_idc and level_idc should indicate the profile and level of the decoder that can decode OlsInScope.

[0272] Constraints on ALF NAL Unit pic_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS referenced by the luma component of the slice associated with the PH.

[0273] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_luma[i], the value of alf_luma_filter_signal_flag is equal to 1.

[0274] The TemporalId of an APS NAL unit having an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_luma[i] is less than or equal to the TemporalId of the picture associated with the PH.

[0275] pic_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS referenced by the chroma component of the PH-related slice.

[0276] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_chroma, the value of alf_chroma_filter_signal_flag is equal to 1.

[0277] The TemporalId of an APS NAL unit having an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_chroma is less than or equal to the TemporalId of the picture associated with the PH.

[0278] Constraints on tile-relative variables The tile-relative variables tile_column_width_minus1[i], tile_row_height_minus1[i], and tile_idx_delta[i] should have several constraints imposed on them to ensure appropriate values ​​for these variables.

[0279] Option A: The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i, within the range of 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. The value of tile_column_width_minus1[i] is within the range of 0 to PicWidthInCtbsY - 1, including 0 and PicWidthInCtbsY - 1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0280] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, the sum of tile_column_width_minus1[i] is less than PicWidthInCtbsY.

[0281] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in CTB units for i, which is in the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. The value of tile_row_height_minus1[i] is in the range from 0 to PicHeightInCtbsY - 1, including 0 and PicHeightInCtbsY - 1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, the sum of tile_row_height_minus1[i] is less than PicHeightInCtbsY.

[0282] Option A': The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0283] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0284] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0285] Option B: tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0286] Option C: Option A + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i, within the range of 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. The value of tile_column_width_minus1[i] is within the range of 0 to PicWidthInCtbsY - 1, including 0 and PicWidthInCtbsY - 1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0287] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, the sum of tile_column_width_minus1[i] is less than PicWidthInCtbsY.

[0288] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in CTB units for i, which is in the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. The value of tile_row_height_minus1[i] is in the range from 0 to PicHeightInCtbsY - 1, including 0 and PicHeightInCtbsY - 1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, the sum of tile_row_height_minus1[i] is less than PicHeightInCtbsY.

[0289] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0290] Option C': Option A' + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0291] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0292] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0293] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0294] Option D: (An alternative to Option A') The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0295] For i within the range from 0 to num_exp_tile_columns_minus1, including 0 and num_exp_tile_columns_minus1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0296] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1, including 0 and num_exp_tile_rows_minus1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0297] Option E: Option D + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0298] For i within the range from 0 to num_exp_tile_columns_minus1, including 0 and num_exp_tile_columns_minus1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0299] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1, including 0 and num_exp_tile_rows_minus1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0300] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0301] Option F: (An alternative to Option A') The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0302] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY. The value of tile_column_width_minus1[num_exp_tile_columns_minus1] is less than PicWidthInCtbsY.

[0303] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY. The value of tile_row_height_minus1[num_exp_tile_rows_minus1] is less than PicHeightInCtbsY.

[0304] Option G: Option F + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0305] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY. The value of tile_column_width_minus1[num_exp_tile_columns_minus1] is less than PicWidthInCtbsY.

[0306] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY. The value of tile_row_height_minus1[num_exp_tile_rows_minus1] is less than PicHeightInCtbsY.

[0307] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0308] In the above, the statement "M is less than or equal to N" regarding the two values ​​M and N can also be expressed as "M does not exceed N."

[0309] The different implementations of this application are as follows:

[0310] First embodiment [DPS ID] Currently, DPS has a DPS ID, and there are no restrictions on the correspondence between the contents of the DPS NAL unit and the ID value.

[0311] Furthermore, there is no limit to the number of times a DPS can be present in a bitstream. If many DPS exist in the bitstream and they all have the same DPS ID, the decoder does not know which DPS to select.

[0312] Two options are offered to address this problem.

[0313] Option A: Add a constraint that a DPS can only exist at most once in a bitstream, meaning that a DPS is not required in a bitstream, and if a bitstream contains a DPS, only one DPS can exist in the bitstream.

[0314] The DPS RBSP becomes available to the decryption process before being referenced and is contained in at least one AU whose TemporalId is equal to 0, or is provided by an external means.

[0315] Note 1 -- A maximum of one DPS NAL unit exists within the bitstream.

[0316] Note 2 -- The DPS NAL unit must be available to the decoding process (either in the bitstream or by external means) before it is referenced. However, the DPS RBSP contains information that is not necessary for the operation of the decoding process as defined in Sections 2 through 9 of this Specification.

[0317] Option B: Add a constraint that all DPS NAL units with a specific value for dps_decoding_parameter_set_id in the bitstream have the same content. In this case, one DPS ID cannot hook (correspond) to the content of two or more DPS.

[0318] for example, The DPS RBSP becomes available to the decryption process before being referenced and is contained in at least one AU whose TemporalId is equal to 0, or is provided by an external means. Note 1 -- The DPS NAL unit must be available to the decoding process (either in the bitstream or by external means) before it is referenced. However, the DPS RBSP contains information that is not necessary for the operation of the decoding process as defined in Sections 2 through 9 of this Specification.

[0319] All DPS NAL units with a specific value for dps_decoding_parameter_set_id in the bitstream have the same content.

[0320] Second Embodiment [DPS Level] The level signaled within DPS should represent the worst-case capability of the entire bitstream, or the worst-case capability, and therefore should be greater than or equal to the level signaled within SPS. A constraint may be imposed that the level signaled within DPS should not be lower than the level signaled within SPS.

[0321] general_level_idc indicates the level to which OlsInScope conforms, as specified in Appendix A. The bitstream does not contain any general_level_idc values ​​other than those specified in Appendix A. Other values ​​for general_level_idc are reserved by ITU-T | ISO / IEC for future use. Note 1 -- A larger value for general_level_idc indicates a higher level. The maximum level signaled within the DPS for OlsInScope is not less than the level signaled within the SPS for CVS included in OlsInScope. Note 2 -- When OlsInScope conforms to multiple profiles, general_profile_idc should indicate the profile that provides the preferred decoded result or preferred bitstream identification information, as determined by the encoder (not specified herein). Note 3 -- When the --profile_tier_level() syntax structure is included in the DPS and the CVS of OlsInScope conforms to different profiles, general_profile_idc and level_idc should indicate the profile and level of the decoder that can decode OlsInScope.

[0322] Third embodiment [ALF nalu's tid] Currently, there are no constraints on the TemporalId of an APS NAL unit or the TemporalId of a picture associated with a PH. However, when nal_unit_type is equal to PPS_NUT, PREFIX_APS_NUT, or SUFFIX_APS_NUT, the TemporalId should be greater than or equal to the TemporalId of the PU containing the NAL unit, and in bitstream subtraction scenarios, there should be constraints on the TemporalId of an APS NAL unit and the TemporalId of a picture associated with a PH.

[0323] Constraints on ALF NAL Unit pic_alf_aps_id_luma[i] specifies the adaptation_parameter_set_id of the i-th ALF APS referenced by the luma component of the slice associated with the PH.

[0324] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_luma[i], the value of alf_luma_filter_signal_flag is equal to 1.

[0325] The TemporalId of an APS NAL unit having an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_luma[i] is less than or equal to the TemporalId of the picture associated with the PH.

[0326] pic_alf_aps_id_chroma specifies the adaptation_parameter_set_id of the ALF APS referenced by the chroma component of the PH-related slice.

[0327] For an APS NAL unit with an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_chroma, the value of alf_chroma_filter_signal_flag is equal to 1.

[0328] The TemporalId of an APS NAL unit having an aps_params_type equal to ALF_APS and an adaptation_parameter_set_id equal to pic_alf_aps_id_chroma is less than or equal to the TemporalId of the picture associated with the PH.

[0329] Fourth embodiment [tile] The tile-relative variables tile_column_width_minus1[i], tile_row_height_minus1[i], and tile_idx_delta[i] should have several constraints imposed on them to ensure appropriate values ​​for these variables.

[0330] This is because none of these variables for any tile can exceed the boundaries of the picture. Also, the tile row and tile height must be greater than 0.

[0331] Option A: The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i, within the range of 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. The value of tile_column_width_minus1[i] is within the range of 0 to PicWidthInCtbsY - 1, including 0 and PicWidthInCtbsY - 1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1. For i within the range from 0 to num_exp_tile_columns_minus1 - 1, the sum of tile_column_width_minus1[i] is less than PicWidthInCtbsY.

[0332] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in CTB units for i, which is in the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. The value of tile_row_height_minus1[i] is in the range from 0 to PicHeightInCtbsY - 1, including 0 and PicHeightInCtbsY - 1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, the sum of tile_row_height_minus1[i] is less than PicHeightInCtbsY.

[0333] Option A': The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1. For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0334] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0335] Option B: Ensure that the rectangular slice is included in the picture.

[0336] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0337] Option C: Option A + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i, within the range of 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. The value of tile_column_width_minus1[i] is within the range of 0 to PicWidthInCtbsY - 1, including 0 and PicWidthInCtbsY - 1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1. For i within the range from 0 to num_exp_tile_columns_minus1 - 1, the sum of tile_column_width_minus1[i] is less than PicWidthInCtbsY.

[0338] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in CTB units for i, which is in the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. The value of tile_row_height_minus1[i] is in the range from 0 to PicHeightInCtbsY - 1, including 0 and PicHeightInCtbsY - 1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, the sum of tile_row_height_minus1[i] is less than PicHeightInCtbsY.

[0339] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0340] Option C': Option A' + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1. For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0341] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0342] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0343] Option D: (An alternative to Option A') The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0344] For i within the range from 0 to num_exp_tile_columns_minus1, including 0 and num_exp_tile_columns_minus1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0345] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1, including 0 and num_exp_tile_rows_minus1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0346] Option E: Option D + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0347] For i within the range from 0 to num_exp_tile_columns_minus1, including 0 and num_exp_tile_columns_minus1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY.

[0348] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1, including 0 and num_exp_tile_rows_minus1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY.

[0349] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0350] Option F: (An alternative to Option A') The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0351] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY. The value of tile_column_width_minus1[num_exp_tile_columns_minus1] is less than PicWidthInCtbsY.

[0352] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY. The value of tile_row_height_minus1[num_exp_tile_rows_minus1] is less than PicHeightInCtbsY.

[0353] Option G: Option F + Option B The value of tile_column_width_minus1[i] plus 1 specifies the width of the i-th tile column in units of CTB for i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1. tile_column_width_minus1[num_exp_tile_columns_minus1] is used to derive the width of tile columns with indices greater than or equal to num_exp_tile_columns_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_column_width_minus1

[0000] is presumed to be equal to PicWidthInCtbsY - 1.

[0354] For i within the range from 0 to num_exp_tile_columns_minus1 - 1, including 0 and num_exp_tile_columns_minus1 - 1, the sum of (tile_column_width_minus1[i] + 1) is less than or equal to PicWidthInCtbsY. The value of tile_column_width_minus1[num_exp_tile_columns_minus1] is less than PicWidthInCtbsY.

[0355] The value of tile_row_height_minus1[i] plus 1 specifies the height of the i-th tile row in units of CTB for i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1. tile_row_height_minus1[num_exp_tile_rows_minus1] is used to derive the height of tile rows with an index greater than or equal to num_exp_tile_rows_minus1, as specified in Section 6.5.1. If it does not exist, the value of tile_row_height_minus1

[0000] is presumed to be equal to PicHeightInCtbsY - 1. For i within the range from 0 to num_exp_tile_rows_minus1 - 1, including 0 and num_exp_tile_rows_minus1 - 1, the sum of (tile_row_height_minus1[i] + 1) is less than or equal to PicHeightInCtbsY. The value of tile_row_height_minus1[num_exp_tile_rows_minus1] is less than PicHeightInCtbsY.

[0356] tile_idx_delta[i] specifies the difference in tile indices between the i-th rectangular slice and the (i + 1)-th rectangular slice. The value of tile_idx_delta[i] is within the range of -NumTilesInPic + 1 to NumTilesInPic - 1, including -NumTilesInPic + 1 and NumTilesInPic - 1. If none exists, the value of tile_idx_delta[i] is presumed to be equal to 0. In all other cases, the value of tile_idx_delta[i] is not equal to 0. For i within the range of 0 to num_slices_in_pic_minus1 - 1, including 0 and num_slices_in_pic_minus1 - 1, the sum of tile_idx_delta[i] is less than NumTilesInPic.

[0357] In the above, the statement "M is less than or equal to N" regarding the two values ​​M and N can also be expressed as "M does not exceed N."

[0358] (1) The constraint that a DPS can exist at most once in a bitstream, and another mechanism that ensures all DPS NAL units with a specific value of dps_decoding_parameter_set_id in the bitstream have the same content when a bitstream can have two or more DPSs, reduces or eliminates ambiguity in the decoder.

[0359] (2) The level signaled within DPS should be the worst-case capability of the entire bitstream and therefore should not be lower than the level signaled within SPS. Otherwise, the parameters within DPS are meaningless.

[0360] (3) Depending on the TID of the NALU, a constraint is added on the TID of the ALF NALU to ensure that bitstream subtraction works correctly.

[0361] (4) From a compliance standpoint, tile relative variables should be constrained to a range to ensure that each tile has at least one CTU, and each tile should be contained by a picture. Also ensure that rectangular slices are contained by a picture.

[0362] The following describes applications of the encoding and decoding methods shown in the embodiments described above, as well as systems that use them.

[0363] Figure 6 is a block diagram illustrating a content supply system for realizing a content distribution service. This content supply system 3100 includes a capture device 3102, a terminal device 3106, and optionally a display 3126. The capture device 3102 communicates with the terminal device 3106 via a communication link 3104. The communication link may include the communication channel 13 described above. Examples of the communication link 3104 include, but are not limited to, Wi-Fi, Ethernet, cable, wireless (3G / 4G / 5G), USB, or any combination of these.

[0364] The capture device 3102 may generate data and encode the data using the encoding method shown in the above embodiment. Alternatively, the capture device 3102 may deliver the data to a streaming server (not shown), which encodes the data and transmits the encoded data to the terminal device 3106. Examples of the capture device 3102 include, but are not limited to, a camera, a smartphone or smartpad, a computer or laptop, a video conferencing system, a PDA, an in-vehicle device, or any combination thereof. For example, the capture device 3102 may include the source device 12 described above. When the data includes video, the video encoder 20 included in the capture device 3102 may actually perform the video encoding process. When the data includes audio (i.e., voice), the audio encoder included in the capture device 3102 may actually perform the audio encoding process. In some practical scenarios, the capture device 3102 delivers the encoded video and audio data by multiplexing them together. In other practical scenarios, for example in a video conferencing system, the encoded audio data and encoded video data are not multiplexed. The capture device 3102 distributes the encoded audio data and encoded video data separately to the terminal device 3106.

[0365] In the content supply system 3100, the terminal device 3106 receives and plays back encoded data. The terminal device 3106 can be any device capable of receiving and recovering data, such as a smartphone or smartpad 3108, a computer or laptop 3110, a network video recorder (NVR) / digital video recorder (DVR) 3112, a TV 3114, a set-top box (STB) 3116, a video conferencing system 3118, a video surveillance system 3120, a personal digital assistant (PDA) 3122, an in-vehicle device 3124, or any combination thereof, that can decode the encoded data described above. For example, the terminal device 3106 may include the destination device 14 described above. When the encoded data includes video, the video decoder 30 included in the terminal device is preferred for performing video decoding. When the encoded data includes audio, the audio decoder included in the terminal device is preferred for performing audio decoding.

[0366] For terminal devices with a display, such as a smartphone or smartpad 3108, a computer or laptop 3110, a network video recorder (NVR) / digital video recorder (DVR) 3112, a TV 3114, a personal digital assistant (PDA), or an in-vehicle device 3124, the terminal device can supply the decoded data to its display. For terminal devices without a display, such as an STB 3116, a video conferencing system 3118, or a video surveillance system 3120, the decoded data is received and displayed on an external display 3126.

[0367] When each device in this system performs encoding or decoding, the picture encoding device or picture decoding device shown in the above embodiment may be used.

[0368] Figure 7 shows the structure of an example terminal device 3106. After the terminal device 3106 receives a stream from the capture device 3102, the protocol progression unit 3202 analyzes the transmission protocol of the stream. Examples of protocols include, but are not limited to, Real-Time Streaming Protocol (RTSP), Hypertext Transfer Protocol (HTTP), HTTP Live Streaming Protocol (HLS), MPEG-DASH, Real-Time Transport Protocol (RTP), Real-Time Messaging Protocol (RTMP), or any combination of these.

[0369] After the protocol processing unit 3202 processes the stream, a stream file is generated. The file is output to the multiplexing / decompression unit 3204. The multiplexing / decompression unit 3204 can separate the multiplexed data into encoded audio data and encoded video data. As described above, in some scenarios, for example in a video conferencing system, the encoded audio data and encoded video data are not multiplexed. In this situation, the encoded data is sent to the video decoder 3206 and audio decoder 3208 without passing through the multiplexing / decompression unit 3204.

[0370] Multiplexing processes generate a video elementary stream (ES), an audio ES, and optionally subtitles. A video decoder 3206, including the video decoder 30 described in the above embodiments, decodes the video ES using the decoding method shown in the above embodiments to generate video frames and supplies this data to the synchronization unit 3212. An audio decoder 3208 decodes the audio ES to generate audio frames and supplies this data to the synchronization unit 3212. Alternatively, video frames may be stored in a buffer (not shown in Figure 7) before being supplied to the synchronization unit 3212. Similarly, audio frames may be stored in a buffer (not shown in Figure 7) before being supplied to the synchronization unit 3212.

[0371] The synchronization unit 3212 synchronizes video frames and audio frames and supplies video / audio to the video / audio display 3214. For example, the synchronization unit 3212 synchronizes the presentation of video and audio information. The information may be coded in a syntax that uses timestamps for the presentation of coded audio and visual data, as well as timestamps for the delivery of the data stream itself.

[0372] If subtitles are included in the stream, the subtitle decoder 3210 decodes the subtitles, synchronizes them with the video and audio frames, and supplies the video / audio / subtitles to the video / audio / subtitle display 3216.

[0373] Embodiments of the present invention are not limited to the systems described above, and either the picture encoding device or the picture decoding device of the embodiments described above may be incorporated into other systems, such as automotive systems.

[0374] Mathematical operators The mathematical operators used in this application are similar to those used in the C programming language. However, the results of integer division and arithmetic shift operations are more strictly defined, and additional operations such as exponentiation and real-valued division are defined. The numbering and counting rules generally start from 0, for example, "1st" is equivalent to 0, "2nd" is equivalent to 1, and so on.

[0375] Arithmetic operators The following arithmetic operators are defined as follows: + Addition - Subtraction (as a two-argument operator) or negation (as a unary prefix operator) * Multiplication including matrix multiplication x yExponentiation. Defines x to the power of y. In other contexts, such notation is used for superscript writing that is not intended to be interpreted as an exponentiation. The / operator performs integer division, truncating the result to zero. For example, 7 / 4 and -7 / -4 are truncated to 1, while -7 / 4 and 7 / -4 are truncated to -1. The division operator (÷) is used to represent division in mathematical equations where truncation or rounding is not intended.

[0376]

number

[0377] It is used to represent division in mathematical equations where truncation or rounding is not intended.

[0378]

number

[0379] The sum of f(i), where i takes all integer values ​​from x to y, including y. The x % y method. The remainder of x divided by y, defined only for integers x and y such that x >= 0 and y > 0.

[0380] Logical operators The following logical operators are defined as follows: x && y: Boolean "product" of x and y x || y Boolean "union" of x and y ! Boolean logic "negation" x ? y : If x is true or not equal to 0, it evaluates to the value y; otherwise, it evaluates to the value z.

[0381] Relational operators The following relational operators are defined as follows: > larger >= Above < Less than <= The following == Equal != Not equal

[0382] When a relational operator is applied to a syntax element or variable to which the value "na" (not applicable) is assigned, the value "na" is treated as a distinct value with respect to the syntax element or variable. The value "na" is considered not equal to any other value.

[0383] Bitwise operators The following bitwise operators are defined as follows. & Bitwise "logical AND". When operating on integer arguments, it acts on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by adding leading bits equal to 0. | Bitwise "logical OR". When operating on integer arguments, it acts on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by adding leading bits equal to 0. ^ Bitwise "exclusive OR". When operating on integer arguments, it acts on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than the other argument, the shorter argument is extended by adding leading bits equal to 0. x>>y Arithmetic right shift of the two's complement representation of the integer x by y bits. This function is defined only for non - negative integer values of y. The bit shifted into the most significant bit (MSB) as a result of the right shift has the same value as the MSB of x before the shift operation. )]]x<<y Arithmetic left shift of the two's complement representation of the integer x by y bits. This function is defined only for non - negative integer values of y. The bit shifted into the least significant bit (LSB) as a result of the left shift has a value equal to 0.

[0384] Assignment operators The following arithmetic operators are defined as follows. = Assignment operator The increment operator ++, i.e., x++, is equivalent to x = x + 1 and, when used as an array index, evaluates to the value of the variable before the increment operation. -- Decrement, i.e., x -- is equivalent to x = x - 1, and when used as an array index, it evaluates to the value of the variable before the decrement operation. += increments a specified amount; that is, x += 3 is equivalent to x = x + 3, and x += (-3) is equivalent to x = x + (-3). -= decrements a specified quantity; that is, x -= 3 is equivalent to x = x - 3, and x -= (-3) is equivalent to x = x - (-3).

[0385] Range notation The following notation is used to specify a range of values. x = y..zx takes integer values ​​from y to z, including y and z, where x, y, and z are integers and z is greater than y.

[0386] Mathematical functions The following mathematical function is defined.

[0387]

number

[0388] Asin(x) is a trigonometric inverse sine function that acts on an argument x in the range of -1.0 to 1.0, including -1.0 and 1.0, and has output values ​​in radians in the range of -π÷2 to π÷2, including -π÷2 and π÷2. Atan(x) is the trigonometric inverse tangent function that acts on the argument x and has an output value in radians ranging from -π÷2 to π÷2, including -π÷2 and π÷2.

[0389]

number

[0390] Ceil(x) The smallest integer greater than or equal to x. Clip1 Y ( x ) = Clip3( 0, ( 1 << BitDepth Y ) - 1, x ) Clip1 C ( x ) = Clip3( 0, ( 1 << BitDepth C ) - 1, x )

[0391]

number

[0392] Cos(x) is the trigonometric cosine function acting on an argument x in radians. Floor(x): The largest integer less than or equal to x.

[0393]

number

[0394] Ln(x) is the natural logarithm of x (a logarithm with base e, where e is the base constant of the natural logarithm, 2.718281828...). Log2(x) is the logarithm of x with base 2. Log10(x) is the base-10 logarithm of x.

[0395]

number

[0396]

number

[0397] Round( x ) = Sign( x ) * Floor( Abs( x ) + 0.5 )

[0398]

number

[0399] Sin(x) is the trigonometric sine function acting on an argument x in radians.

[0400]

number

[0401] Swap(x, y) = (y, x) Tan(x) is the trigonometric tangent function that acts on an argument x in radians.

[0402] Order of operations When precedence in an expression is not explicitly indicated using parentheses, the following rules apply: Operations with higher priority are evaluated before any operations with lower priority. Operations with the same priority are evaluated from left to right.

[0403] The table below clearly shows the order of operations from highest to lowest, with higher positions in the table indicating higher priority.

[0404] With respect to operators also used in the C programming language, the precedence used herein is the same as that used in the C programming language.

[0405] Table: Priority of operations from the highest (top of the table) to the lowest (bottom of the table)

[0406] [Table 6]

[0407] Text description of logical operations In the text, in the following form, namely, if (condition 0) Statement 0 else if (condition 1) Statement 1 ... else / * Comment providing information about the remaining conditions * / statement n Statements of logical operations, mathematically described in this form, can be written as follows: The following applies: - If condition 0, statement 0 - Instead, if condition 1 is true, then statement 1 - ... - Otherwise (comments providing information about the remaining conditions), statement n

[0408] Each "If..., ..., otherwise..., ..., ..." statement in the text is introduced by "If..., ..." immediately followed by "The following applies..." or "The following applies...". The final condition of "If..., ..., otherwise..., ..., ..., ..., ..." is always "The following applies...". Alternating "If..., ..., otherwise..., ..., ..., ..." statements can be identified by matching "The following applies..." or "The following applies..." with the final "The following applies...".

[0409] In the text, in the following form, namely, if( condition 0a && condition 0b ) Statement 0 else if( condition 1a || condition 1b ) Statement 1 ... else statement n Statements of logical operations that are mathematically described in this form may be written as follows: The following applies: - If all of the following conditions are true, then statement 0 - Condition 0a - Condition 0b - Instead, if one or more of the following conditions are true, then Statement 1 - Condition 1a - Condition 1b - ... - Otherwise, statement n

[0410] In the text, in the following form, namely, if (condition 0) Statement 0 if (Condition 1) Statement 1 Statements of logical operations, mathematically described in this form, can be written as follows: When condition 0, statement 0 When condition 1 is met, statement 1

[0411] Although embodiments of the present invention have been described primarily in relation to video coding, it should be noted that embodiments of the coding system 10, encoder 20, and decoder 30 (and correspondingly system 10), as well as other embodiments described herein, may be configured for processing or coding still pictures, i.e., for processing or coding individual pictures independently of any preceding or consecutive pictures, similar to video coding. Generally, when the coding of picture processing is limited to a single picture 17, only the interpretation units 244 (encoder) and 344 (decoder) may not be available. All other functions (also called tools or technologies) of the video encoder 20 and video decoder 30, such as residual calculation 204 / 304, transformation 206, quantization 208, inverse quantization 210 / 310, (inverse) transformation 212 / 312, partitioning 262 / 362, intra prediction 254 / 354, and / or loop filtering 220, 320, and entropy coding 270, and entropy decoding 304 may be used equally for processing still pictures.

[0412] For example, the encoder 20 and decoder 30, and embodiments of the functions described herein in relation to the encoder 20 and decoder 30, for example, may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium or transmitted over a communication medium and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium such as a data storage medium, or a communication medium including any medium that facilitates the transfer of computer programs from one place to another, for example, by a communication protocol. Thus, generally speaking, the computer-readable medium may correspond to (1) a non-transient, tangible computer-readable storage medium or (2) a communication medium such as a signal or carrier wave. The data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementations of the technologies described herein. Computer program products may include computer-readable medium.

[0413] In particular, a method is provided for decoding a coded video bitstream, which is performed in a decoder as shown in Figure 8, the method comprising: S801, parsing the video bitstream to obtain a picture-level syntax element contained in the picture header of the current picture, wherein the picture-level syntax element (e.g., pic_alf_enabled_flag) is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture; S802, if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, obtaining a parameter set identifier (e.g., pic_alf_aps_id_luma[i]) contained in the picture header, wherein the parameter set identifier is used to indicate a first parameter set (e.g., APS) containing a set of ALF parameters, and the time identifier (e.g., TemporalId) of the first parameter set is less than or equal to the time identifier of the current picture; and S803, performing an adaptive loop filter on at least one slice of the current picture based on the first parameter set.

[0414] The current picture is a coded picture contained within a picture unit (PU), where a PU is a set of NAL units that are related to each other according to a specified classification rule and are consecutive in decoding order.

[0415] A Network Abstraction Layer (NAL) unit is a syntactic structure that includes an indication of the type of data that follows, and bytes containing all or part of the encoded data of the current picture, a picture header, or a parameter set containing a set of ALF parameters, where each NAL unit has a time identifier.

[0416] The time identifier (e.g., TemporalId) of the first parameter set is the TemporalId of the APS NAL unit having an aps_params_type equal to ALF_APS. an aps_params_type equal to ALF_APS means that the ALF parameters are carried within the APS. The APS NAL unit is the NAL unit that contains the APS.

[0417] If the time identifier of the first NAL unit is less than the time identifier of the second NAL unit in the same layer, the data encapsulated by the first NAL unit may be decoded without referencing the data encapsulated by the second NAL unit. The time identifier may also be used in a sub-bitstream extraction process, which is a process in which NAL units in the bitstream that do not belong to the target set determined by the target highest time identifier are removed from the bitstream, and the output sub-bitstream consists of NAL units in the bitstream that belong to the target set.

[0418] The time identifier may be related to the decoding order.

[0419] The step of performing an adaptive loop filter on at least one slice of the current picture based on a first set of parameters includes performing an adaptive loop filter on the luma component of at least one slice of the current picture based on a first set of parameters.

[0420] When ALF is enabled for CTB, each sample R(i, j) in CU is filtered using ALF, as shown below, to produce a sample value R'(i, j).

[0421]

number

[0422] f(k, l) represents the decoded filter coefficients, K(x, y) is the clipping function, and c(k, l) represents the decoded clipping parameters. The variables k and l vary between -L / 2 and L / 2, where L represents the filter length. The clipping function K(x, y) = min(y, max(-y, x)), which corresponds to the function Clip3(-y, y, x). The clipping operation introduces nonlinearity to make the ALF more efficient by reducing the influence of neighboring sample values ​​that are too different from the current sample value.

[0423] ALF filter parameters (or ALF parameters) are signaled within an Adaptive Parameter Set (APS). Within a single APS, up to 25 sets of luminous filter coefficients and clipping value indices, and up to 8 sets of chroma filter coefficients and clipping value indices, may be signaled. To reduce bit overhead, filter coefficients of different classifications for luminous components may be merged. Within the picture header, the index of the APS used for the current picture is signaled.

[0424] The index of the clipping value decoded from the APS allows for the determination of the clipping value using a table of clipping values ​​for both the luma and chroma components. These clipping values ​​depend on the internal bit depth. More precisely, the clipping value is given by the following formula, i.e., AlfClip = {round(2 B-α*n )} for n ∈ [0..N - 1]} AlfClip is obtained by , where B is equal to the internal bit depth, α is a predefined constant value equal to 2.35, and N is equal to 4, which is the number of allowed clipping values ​​in VVC. Then AlfClip is rounded to the nearest value in the form of a power of 2.

[0425] Within the slice header, up to seven APS indices may be signaled to specify the Luma filter set to be used for the current slice. The filtering process can be further controlled at the CTB level. A flag is always signaled to indicate whether the ALF is applied to the Luma CTB. The Luma CTB can select a filter set from 16 fixed filter sets and filter sets from APS. A filter set index is signaled with respect to the Luma CTB to indicate which filter set is applied. The 16 fixed filter sets are predefined and hardcoded in both the encoder and decoder.

[0426] Regarding chroma components, the APS index is signaled within the slice header to indicate the chroma filter set being used for the current slice. At the CTB level, if there are two or more chroma filter sets within the APS, a filter index is signaled for each chroma CTB.

[0427] The filter coefficients are quantized using a norm equal to 128. To limit the complexity of the multiplication, bitstream conformance is applied so that the coefficient values ​​at non-center positions are within the range of -27 to 27-1, including -27 and 27-1. The coefficients at center positions are not signaled within the bitstream and are considered equal to 128.

[0428] The method may further include, if a picture-level syntax element (e.g., pic_alf_enabled_flag) specifies that an adaptive loop filter should be enabled for the current picture, the steps of: obtaining another parameter set identifier contained in the picture header, wherein the parameter set identifier (e.g., pic_alf_aps_id_chroma) is used to indicate a second parameter set (e.g., APS) containing a set of ALF parameters, and the time identifier of the second parameter set is less than or equal to the time identifier of the current picture; and performing an adaptive loop filter on the chroma components of at least one slice of the current picture based on the second parameter set.

[0429] Similarly, a method for encoding a video bitstream containing coded data is provided, which is performed in an encoder as shown in Figure 9. The method includes the steps of: S901, determining whether an adaptive loop filter (ALF) is enabled for the current picture; S903, based on the determination of whether an adaptive loop filter (ALF) is enabled for the current picture, encoding a picture-level syntax element (e.g., pic_alf_enabled_flag) in the picture header of the current picture, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture; and S905, if an adaptive loop filter is enabled for the current picture, encoding a parameter set identifier (e.g., pic_alf_aps_id_luma[i]) in the picture header, wherein the parameter set identifier is used to indicate a first parameter set (e.g., APS) containing a set of ALF parameters for the adaptive loop filter, and the time identifier (e.g., TemporalId) of the first parameter set is set to be less than or equal to the time identifier of the current picture.

[0430] The method may further include the step of encoding the time identifier of the first parameter set and the time identifier of the current picture into a video bitstream.

[0431] The first parameter set includes a set of ALF parameters for an adaptive loop filter that is applied to the luma component of at least one slice of the current picture.

[0432] The method, when a picture-level syntax element specifies that an adaptive loop filter should be enabled for the current picture, further comprises the step of encoding another parameter set identifier in the picture header, wherein the parameter set identifier (e.g., pic_alf_aps_id_chroma) is used to indicate a second parameter set (e.g., APS) containing a set of ALF parameters for an adaptive loop filter to be performed on the chroma components of at least one slice of the current picture, and the time identifier of the second parameter set is set to be less than or equal to the time identifier of the current picture.

[0433] Figure 10 shows a decoder 1000 configured to decode a video bitstream containing coded data for multiple pictures. The decoder 1000 in the example shown includes an acquisition unit 1010 configured to obtain a picture-level syntax element contained in the picture header of the current picture by parsing the video bitstream, the picture-level syntax element being used to specify whether an adaptive loop filter (ALF) is enabled for the current picture. The acquisition unit 1010 is further configured to obtain a parameter set identifier contained in the picture header if the picture-level syntax element specifies that an adaptive loop filter is enabled for the current picture, the parameter set identifier being used to indicate a first parameter set containing a set of ALF parameters, the time identifier of the first parameter set being less than or equal to the time identifier of the current picture, and the filtering unit 1020 being configured to perform the adaptive loop filter on at least one slice of the current picture based on the first parameter set.

[0434] The acquisition unit 1010 may be an entropy decoding unit 304. The filtering unit 1020 may be a loop filter 320. The decoder 1000 may be a destination device 14, a decoder 30, a device 500, a video decoder 3206, or a terminal device 3106.

[0435] Similarly, an encoder 1100 is provided, configured to encode a video bitstream containing coded data for multiple pictures, as shown in Figure 11. The encoder 1100 includes a determination unit 1110 configured to determine whether an adaptive loop filter (ALF) is enabled for the current picture, and an encoding unit 1120 configured to encode a picture-level syntax element into the picture header of the current picture, based on the determination of whether an adaptive loop filter (ALF) is enabled for the current picture, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture. The encoding unit 1120 is further configured to encode a parameter set identifier into the picture header if the adaptive loop filter is enabled for the current picture, the parameter set identifier is used to indicate a first parameter set containing a set of ALF parameters for the adaptive loop filter, and the time identifier of the first parameter set is set to be less than or equal to the time identifier of the current picture.

[0436] The encoding unit 1120 may be an entropy encoding unit 270. The determination unit 1110 may be a loop filter 220. The encoder 1100 may be the source device 12, the encoder 20, or the device 500.

[0437] As an example, and not an limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other media that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is appropriately called computer-readable media. For example, if instructions are transmitted from a website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio waves, and microwaves, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio waves, and microwaves are included in the definition of media. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals, or other temporary media, but instead refer to non-temporary, tangible storage media. As used herein, "disk" and "disc" include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where a disk typically reproduces data magnetically, while a disc reproduces data optically using a laser. Combinations of the above should also be included in the scope of computer-readable media.

[0438] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, when used herein, the term “processor” may refer to either the above-described structures or any other structure suitable for implementing the technologies described herein. In addition, in some embodiments, the functions described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Furthermore, the technologies may all be implemented in one or more circuits or logic elements.

[0439] The technology disclosed herein may be implemented in a wide variety of devices or apparatus, including wireless handsets, integrated circuits (ICs), or a set of ICs (e.g., a chipset). Various components, modules, or units are described herein to highlight the aspects of functionality of a device configured to perform the disclosed technology, but implementation by different hardware units is not necessarily required. Rather, as described above, various units may be combined in a codec hardware unit or provided by a set of interoperable hardware units, including one or more of the aforementioned processors, in conjunction with suitable software and / or firmware. [Explanation of symbols]

[0440] 10 Video coding system, coding system 12. Source device 13 Encoded picture data, communication channel 14 Destination device 16 Picture Sources 17. Picture, picture data, raw picture, raw picture data, monochrome picture, color picture, current picture 18 Preprocessors, pre-processing units, picture preprocessors 19 Pre-processed pictures, pre-processed picture data 20 video encoders, encoders 21 Encoded picture data, encoded bitstream 22 Communication interface, communication unit 28 Communication interface, communication unit 30 decoders, video decoders 31 Decrypted picture data, decrypted picture 32 Post-processors, Post-processing Units 33 Post-processed picture data, post-processed picture 34 Display Devices 46 Processing Circuit 100 video encoders 201 Input, Input Interface 203 Picture Block, Original Block, Current Block, Current Picture Block, CTU 204 Residual Calculation Unit, Residual Calculation 205 Residual block, residual 206 Conversion processing unit, conversion 207 Conversion coefficient 208 Quantization Unit, Quantization 209 Quantized coefficients, quantized transformation coefficients, quantized residual coefficients 210 Inverse Quantization Unit, Inverse Quantization 211 Inverse quantized coefficients, inverse quantized residual coefficients 212 Inverse transformation processing unit, (inverse) transformation 213 Reconstructed residual blocks, inversely quantized coefficients, transform blocks 214 Reconstruction Unit, Adder, Combiner 215 Reconstructed Blocks 216 buffers 220 Loop Filter Unit, Loop Filter 221 Filtered blocks, filtered and reconstructed blocks 230 Decoded Picture Buffer (DPB) 231 Decrypted picture 244 Interpretation Units (Encoders) 254 Intra Prediction Unit, Inter Prediction Unit, Intra Prediction 260 Mode Selection Unit 262 division units, division 265 prediction blocks, predictors 266 Syntax Elements 270 Entropy coding units, entropy coding 272 outputs, output interface 304 Residual calculation, entropy decoding, entropy decoding unit 309 Quantized coefficients 310 Inverse Quantization Unit, Inverse Quantization 311 Inverse quantized coefficients, transformation coefficients 312 Inverse conversion processing unit, output, (inverse) conversion 313 Reconstructed residual block 314 Reconstruction Unit, Combiner, Adder 315 Reconstructed Blocks 320 Loop Filters, Loop Filter Units, Loop Filtering Units 321 Filtered blocks, decoded video blocks 330 Decoded Picture Buffer (DPB) 331 Decrypted picture 344 Interpretation Unit (Decoder) 354 Intra Prediction Unit, Intra Prediction 360 Mode Applicable Unit 362 divisions 365 Prediction Block 400 video coding devices 410 Incoming port, input port 420 Receiver Unit (Rx) 430 Processors, Logical Units, Central Processing Units (CPUs) 440 Transmitter Unit (Tx) 450 outgoing ports, output ports 460 memory 470 coding modules 500 devices 502 Processors 504 memory 506 data 508 Operating Systems 510 Application Programs 512 Bus 514 Secondary Storage 518 displays 1000 Decoders 1010 units acquired 1020 Filtering Unit 1100 encoder 1110 Judgment Unit 1120 encoding unit 3100 Content Supply System 3102 Capture Device 3104 Communication Link 3106 Terminal device 3108 Smartphones, Smartpads 3110 Computers, Laptops 3112 Network Video Recorder (NVR) / Digital Video Recorder (DVR) 3114 TV 3116 Set-top box (STB) 3118 Video conferencing system 3120 Video Surveillance System 3122 Personal Digital Assistant (PDA) 3124 In-vehicle devices 3126 Display 3202 Protocol Progress Unit 3204 Multiple Separation Unit 3206 Video Decoder 3208 Audio Decoder 3210 Subtitle Decoder 3212 Synchronization Unit 3214 Video / Audio Display 3216 Video / Audio / Subtitle Display

Claims

1. A method for decoding a video bitstream performed by a decoding device, wherein the video bitstream includes data representing the current picture, and the method A step of obtaining a picture-level syntax element contained in the picture header of the current picture by analyzing the video bitstream, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture. If the picture-level syntax element specifies that the adaptive loop filter is enabled for the current picture, the step is to obtain a parameter set identifier contained in the picture header, wherein the parameter set identifier is used to indicate a first parameter set containing a set of ALF parameters, and the time identifier of the first parameter set is less than or equal to the time identifier of the current picture. A method comprising the step of performing the adaptive loop filter on at least one slice of the current picture based on the first set of parameters.

2. The method according to claim 1, wherein the step of performing the adaptive loop filter on at least one slice of the current picture based on the first parameter set is to perform the adaptive loop filter on the luma component of at least one slice of the current picture based on the first parameter set.

3. If the picture-level syntax element specifies that the adaptive loop filter is enabled for the current picture, the step is to obtain another parameter set identifier contained in the picture header, wherein the parameter set identifier is used to indicate a second parameter set containing a set of ALF parameters, and the time identifier of the second parameter set is less than or equal to the time identifier of the current picture. The method according to claim 2, further comprising the step of performing an adaptive loop filter on the chroma components of at least one slice of the current picture based on the second set of parameters.

4. A method for encoding a video bitstream performed by an encoding device, wherein the video bitstream includes data representing the current picture, and the method A step to determine whether the Adaptive Loop Filter (ALF) is enabled for the current picture, A step of encoding a picture-level syntax element into the picture header of the current picture, based on determining whether an adaptive loop filter (ALF) is enabled for the current picture, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture. A method comprising the steps of: when an adaptive loop filter is enabled for the current picture, encoding a parameter set identifier in the picture header, wherein the parameter set identifier is used to indicate a first parameter set containing a set of ALF parameters for the adaptive loop filter, and the time identifier of the first parameter set is set to be less than or equal to the time identifier of the current picture.

5. The method according to claim 4, further comprising the step of encoding the time identifier of the first parameter set and the time identifier of the current picture into the video bitstream.

6. The method according to claim 4 or 5, wherein the first parameter set includes a set of ALF parameters for an adaptive loop filter performed on the luma component of at least one slice of the current picture.

7. The method according to claim 6, further comprising the step of encoding another parameter set identifier in the picture header if the picture-level syntax element specifies that the adaptive loop filter is enabled for the current picture, wherein the parameter set identifier is used to indicate a second parameter set comprising a set of ALF parameters for an adaptive loop filter performed on the chroma components of at least one slice of the current picture, and the time identifier of the second parameter set is set to be less than or equal to the time identifier of the current picture.

8. An encoder comprising a processing circuit for performing the method according to any one of claims 4 to 7.

9. A decoder comprising a processing circuit for performing the method according to any one of claims 1 to 3.

10. A computer program product comprising program code for performing the method described in any one of claims 1 to 9 when executed on a computer or processor.

11. One or more processors, A decoder comprising a non-temporary computer-readable storage medium coupled to the processor and storing a program for execution by the processor, wherein the program is configured to be used to perform the method according to any one of claims 1 to 10 when executed by the processor.

12. One or more processors, An encoder comprising a non-temporary computer-readable storage medium coupled to the processor and storing a program for execution by the processor, wherein the non-temporary computer-readable storage medium configures the encoder to perform the method according to any one of claims 1 to 11 when the program is executed by the processor.

13. A non-temporary computer-readable medium that, when executed by a computer device, carries program code causing the computer device to perform the method according to any one of claims 1 to 12.

14. Non-temporary storage medium comprising an encoded bitstream decoded by an image decoding device, wherein the bitstream is generated by dividing a current picture of a video signal or image signal into a plurality of blocks and comprises a plurality of syntax elements, wherein the plurality of syntax elements comprises a picture-level syntax element contained in the picture header of the current picture by parsing the video bitstream, the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture, and if the picture-level syntax element specifies that the adaptive loop filter is enabled for the current picture, the bitstream further comprises a parameter set identifier contained in the picture header, the parameter set identifier is used to indicate a first parameter set comprising a set of ALF parameters, and the time identifier of the first parameter set is set to be less than or equal to the time identifier of the current picture.

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