Encoder, decoder and corresponding methods of signaling and semantics in parameter sets

Abstract

To provide an encoding and decoding method for performing improved signaling of syntax elements in a sequence parameter set.SOLUTION: A decoding method includes obtaining, from a sequence parameter set (SPS) including syntax elements applied to a video sequence, a value of a first syntax element used to specify whether a decoded picture buffer (DPB) parameter syntax structure is present in the SPS, obtaining, from the SPS, a value of a second syntax element used to specify whether a value of a second syntax element is present in a DPB syntax structure when the value of the first syntax element is determined to specify that the DPB parameter syntax structure is present in the SPS, and applying the DPB syntax element to a temporal sub-layer other than a highest temporal sub-layer in the video sequence.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] FIELD Embodiments of the present application relate generally to the field of picture processing, and more particularly to signaling syntax elements within sequence parameter sets. [Background technology]

[0002] 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, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders in security applications.

[0003] The amount of video data required to render even a relatively short video can be significant, which can pose challenges when the data is to be streamed or otherwise transmitted over communication networks with limited bandwidth capacity. Therefore, video data is generally compressed before being transmitted over modern communication networks. Because memory resources may be limited, video size can also be an issue when the video is stored on a storage device. Often, video compression devices use software and / or hardware at the source to code the video data before transmission or storage, thereby reducing the amount of data needed to represent a digital video image. The compressed data is then received at the destination by a video decompression device, which decodes the video data. With limited network resources and an ever-increasing demand for higher video quality, improved compression and decompression techniques that increase compression ratios with little or no sacrifice in picture quality are desirable.

[0004] In particular, the signaling of syntax elements in sequence parameter sets coded into bitstreams used to provide Decoded Picture Buffer information suffers from inefficiencies and even inconsistencies in techniques (see detailed description below). It is therefore an object of the present application to provide techniques for signaling such syntax elements with improved coding efficiency. Summary of the Invention [Means for solving the problem]

[0005] Embodiments of the present application provide apparatuses and methods for encoding and decoding according to the independent claims.

[0006] These and other objects are achieved by the subject matter of the independent claims. Further implementation forms are evident from the dependent claims, the description and the drawings.

[0007] According to a first aspect, the present invention relates to a method for decoding a video bitstream, implemented by a decoding device, wherein a sequence parameter set (SPS) is coded in the video bitstream and includes syntax elements to be applied to the video sequence. The method includes: obtaining a value of a first syntax element (e.g., a flag) from the SPS, the value of the first syntax element being used to specify whether a decoded picture buffer (DPB) parameter syntax structure is present in the SPS; and, when it is determined that the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS, obtaining a value of a second syntax element (e.g., a flag) from the SPS, the value of the second syntax element being used to specify the presence of a DPB syntax element in the DPB parameter syntax structure, the DPB syntax element being applied to temporal sublayers other than a top-most temporal sublayer in the video sequence.

[0008] For example, the value of the second syntax structure may be obtained only when it is determined that the value of the first syntax element specifies that a DPB parameters syntax structure is present in the SPS. Here and below, the first syntax element may be sps_ptl_dpb_hrd_params_present_flag in accordance with the detailed description below, and the second syntax element may be sps_sublayer_dpb_params_flag in accordance with the detailed description below. Here and below, the DPB syntax element may be one of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] in accordance with the detailed description below.

[0009] The thus provided method for decoding a video bitstream ensures efficient signaling of DPB syntax elements, in particular, the second syntax element, when present, reliably controls the presence of the DPB syntax element in the DPB parameter syntax structure.

[0010] According to implementation, the method further includes obtaining a value of the DPB syntax element based on the value of the second syntax element (e.g., when the second syntax element specifies that the DPB syntax element is present in the DPB parameter syntax structure, in particular, only when the second syntax element specifies that the DPB syntax element is present in the DPB parameter syntax structure), and reconstructing the video sequence based on the value of the DPB syntax element. Thus, reconstruction of the video sequence can be realized based on reliable and efficient signaling of DPB information.

[0011] The step of obtaining the value of the DPB syntax element based on the value of the second syntax element includes: When determining (determined) that the value of the second syntax element specifies that the DPB syntax element is present in the DPB parameter syntax structure, obtaining the value of the DPB syntax element from the DPB parameter syntax structure; or When it is determined that the value of the second syntax element specifies that the DPB syntax element is not present in the DPB parameter syntax structure, the method may include setting the value of the DPB syntax element to be equal to the value of another DPB syntax element that applies to the highest temporal sublayer in the DPB parameter syntax structure.

[0012] This allows one to ensure that definite values ​​of DPB syntax elements are available in all circumstances and can be used to reconstruct video sequences, without having to worry about indeterminate behavior in this regard.

[0013] The thus reliably obtained values ​​of the DPB syntax elements may be used, for example, to configure a DPB to store reference pictures used for inter-prediction processing. Thus, reconstructing a video sequence based on the values ​​of the DPB syntax elements may include configuring a DPB based on the values ​​of the DPB syntax elements and reconstructing the video sequence using the DPB.

[0014] Alternatively, the step of reconstructing the video sequence based on the value of the DPB syntax element may include reconstructing the video sequence based on a determination that the DPB used satisfies the requirements specified by the value of the DPB syntax element. Thus, it may be checked whether the provided DPB is suitable for reconstructing the video sequence.

[0015] According to the implementation, the method for decoding a video bitstream comprises: The method further includes obtaining a value of a third syntax element from the SPS, where the value of the third syntax element is used to determine a maximum number of temporal sub-layers present in the video sequence. The value of the third syntax element may be 0 if only one temporal sub-layer is present. Determining the maximum number of temporal sub-layers present in the video sequence is facilitated by simply signaling the third syntax element, which may be advantageous in terms of coding efficiency.

[0016] Here and below, the third syntax element may be sps_max_sublayers_minus1 according to the detailed description below.

[0017] The step of obtaining the value of the second syntax element from the SPS includes: When it is determined that the value of the first syntax element specifies that a DPB parameter syntax structure is present in the SPS, it may include determining whether a maximum number of temporal sub-layers in the video bitstream is greater than 1 based on the value of the third syntax element, and when it is determined that the maximum number of temporal sub-layers is greater than 1, obtaining a value of the second syntax element from the SPS. For example, the value of the second syntax element may be obtained from the SPS only when it is determined that the maximum number of temporal sub-layers is greater than 1. Thereby, when the maximum number of temporal layers is equal to or less than 1 (i.e., only one temporal sub-layer is present), the value of the second syntax element may not be read at all (e.g., it would be meaningless in this case), and the DPB syntax element may always be signaled in the SPS for a single temporal layer, which may further enhance coding efficiency.

[0018] According to a second aspect, there is provided a method for encoding a video bitstream, implemented by an encoding device, wherein a sequence parameter set SPS is encoded into the video bitstream and comprises syntax elements to be applied to the video sequence, the method exhibiting the same advantages as discussed above. determining the presence of a decoded picture buffer DPB parameters syntax structure in the SPS; encoding a value of a first syntax element (e.g., a flag) into the SPS based on a determination of the presence of the DPB parameter syntax structure in the SPS, the value of the first syntax element being used to specify whether the DPB parameter syntax structure is present in the SPS; When it is determined (e.g., only when it is determined) that a DPB parameter syntax structure is present in the SPS, determining the presence of a DPB syntax element in the DPB parameter syntax structure, wherein the DPB syntax element applies to a temporal sub-layer other than a top-most temporal sub-layer in the video sequence; and a step of encoding a value of a second syntax element (e.g., a flag) into the SPS based on a determination of the presence of the DPB syntax element in the DPB parameter syntax structure, wherein the value of the second syntax element is used to specify the presence of the DPB syntax element in the DPB parameter syntax structure.

[0019] According to implementation, the encoding method further includes, when it is determined that a DPB syntax element is present in the DPB parameter syntax structure, a step of determining a value of the DPB syntax element, and a step of reconstructing a video sequence based on the value of the DPB syntax element.

[0020] According to an implementation, the encoding method further includes a step of setting the value of the DPB syntax element equal to the value of another DPB syntax element that applies to the highest temporal sublayer in the DPB parameter syntax structure, and a step of reconstructing a video sequence based on the value of the DPB syntax element.

[0021] The step of reconstructing the video sequence based on the values ​​of the DPB syntax elements may include configuring the DPB to satisfy the values ​​of the DPB syntax elements, and reconstructing the video sequence using the DPB.

[0022] According to the implementation, the presence of a DPB syntax element in the DPB parameter syntax structure is determined when (e.g., only when) it is determined that a DPB parameter syntax structure exists in the SPS and the maximum number of temporal sublayers in the video bitstream is greater than 1.

[0023] Additionally, an apparatus for decoding and an apparatus for coding a video bitstream are provided, each exhibiting similar advantages as the above-described methods.

[0024] According to a third aspect, there is provided an apparatus for decoding a (coded) video bitstream, the apparatus comprising: an acquisition unit configured to acquire a value of a first syntax element (e.g., a flag) from an SPS, the value of the first syntax element being used to specify whether a decoded picture buffer DPB parameters syntax structure is present in an SPS coded in the video bitstream; and a determining unit configured to determine whether a value of the first syntax element specifies that a DPB parameter syntax structure is present in the SPS; The obtaining unit is further configured to obtain a value of a second syntax element (e.g., a flag) from the SPS at least when it is determined (e.g., only when it is determined) that the value of the first syntax element specifies that a DPB parameter syntax structure is present in the SPS, the value of the second syntax element being used to specify the presence of a DPB syntax element in the DPB parameter syntax structure, and the DPB syntax element being applied to temporal sublayers other than the highest temporal sublayer in the video sequence.

[0025] For example, the value of the second syntax structure may be acquired by the acquiring device only when it is determined that the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS.

[0026] According to implementation, the obtaining unit is further configured to obtain a value of the DPB syntax element based on the value of the second syntax element, and reconstruct the video sequence based on the value of the DPB syntax element.

[0027] Obtaining the value of the DPB syntax element based on the value of the second syntax element When determining (determined) that the value of the second syntax element specifies that the DPB syntax element is present in the DPB parameter syntax structure, obtaining the value of the DPB syntax element from the DPB parameter syntax structure; or When it is determined that the value of the second syntax element specifies that the DPB syntax element is not present in the DPB parameter syntax structure, the method may include setting the value of the DPB syntax element to be equal to the value of another DPB syntax element that applies to the highest temporal sublayer in the DPB parameter syntax structure.

[0028] Reconstructing the video sequence based on the values ​​of the DPB syntax elements may include constructing a DPB based on the values ​​of the DPB syntax elements and reconstructing the video sequence using the DPB.

[0029] Here, the DPB is used to store pictures for building a reference picture list.

[0030] Alternatively, reconstructing the video sequence based on the value of the DPB syntax element may include reconstructing the video sequence based on a determination that the DPB used meets the requirements specified by the value of the DPB syntax element.

[0031] According to the implementation, the acquisition unit is further configured to acquire a value of a third syntax element from the SPS, and the value of the third syntax element is used to determine the maximum number of temporal sub-layers present in the video sequence.

[0032] Retrieving the value of the second syntax element from the SPS is done by When it is determined (determined) that the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS, it may include determining whether the maximum number of temporal sublayers in the video bitstream is greater than 1 based on the value of the third syntax element, and when it is determined (determined) that the maximum number of temporal sublayers is greater than 1, obtaining the value of the second syntax element from the SPS.

[0033] According to a fourth aspect, there is provided an apparatus for encoding a video bitstream, the apparatus comprising: a determining unit configured to determine the presence of a decoded picture buffer DPB parameters syntax structure in the SPS; an encoding unit configured to encode a value of a first syntax element (e.g., a flag) into the SPS based on a determination of the presence of the DPB parameter syntax structure in the SPS, wherein the value of the first syntax element is used to specify whether the DPB parameter syntax structure is present in the SPS; The determining unit is further configured, when determining (when, for example, only when) that a DPB parameter syntax structure is present in the SPS, to determine the presence of a DPB syntax element in the DPB parameter syntax structure, wherein the DPB syntax element applies to a temporal sublayer other than a top-level temporal sublayer in the video sequence; The encoding unit is further configured to encode a value of a second syntax element (e.g., a flag) into the SPS based on a determination of the presence of the DPB syntax element in the DPB parameter syntax structure, wherein the value of the second syntax element is used to specify the presence of the DPB syntax element in the DPB parameter syntax structure.

[0034] According to the implementation, when the determination unit determines (is determined) that a DPB syntax element is present in the DPB parameter syntax structure, the determination unit is further configured to determine a value of the DPB syntax element and reconstruct a video sequence based on the value of the DPB syntax element.

[0035] According to the implementation, the encoding unit is further configured to set the value of the DPB syntax element to be equal to the value of another DPB syntax element that applies to the highest temporal sublayer within the DPB parameter syntax structure, and to reconstruct the video sequence based on the value of the DPB syntax element.

[0036] Reconstructing the video sequence based on the values ​​of the DPB syntax elements may include configuring a DPB to satisfy the values ​​of the DPB syntax elements and reconstructing the video sequence using the DPB.

[0037] According to the implementation, the determination unit is configured to determine that a DPB syntax element is present in the DPB parameter syntax structure when the determination unit determines that the DPB parameter syntax structure is present in the SPS and that the maximum number of temporal sublayers in the video bitstream is greater than 1.

[0038] The above-mentioned methods can be implemented in a decoding device or an encoding device, respectively; thus, an encoder is provided that includes processing circuitry for performing the method for encoding a video bitstream according to any one of the above examples. Further, an encoder is provided that includes one or more processors and a non-transitory computer-readable storage medium, coupled to the processors, that stores programming for execution by the processors, the programming, when executed by the processors, configuring the encoder to perform the method for encoding a video bitstream according to any one of the above examples. Similarly, a decoder is provided that includes processing circuitry for performing the method for decoding a video bitstream according to any one of the above examples, and a decoder is provided that includes one or more processors and a non-transitory computer-readable storage medium, coupled to the processors, that stores programming for execution by the processors, the programming, when executed by the processors, configuring the decoder to perform the method for code decoding a video bitstream according to any one of the above examples.

[0039] Further provided is a computer program product including program code for performing a method according to any one of the above examples when executed on a computer or processor. Similarly, provided is a non-transitory computer readable medium carrying program code that, when executed by a computing device, causes the computing device to perform the method according to any one of the above examples.

[0040] Further provided is a non-transitory storage medium containing an encoded bitstream, wherein the bitstream is generated by dividing a current picture of a video signal or image signal into a plurality of blocks and includes a plurality of syntax elements, wherein the plurality of syntax elements includes a first syntax element in an SPS, wherein a value of the first syntax element is used to specify whether a decoded picture buffer DPB parameters syntax structure is present in the SPS, and when the value of the first syntax element specifies that the DPB parameters syntax structure is present in the SPS, the bitstream further includes a second syntax element in the SPS, wherein a value of the second syntax element is used to specify the presence of a DPB syntax element in the DPB parameters syntax structure, and wherein the DPB syntax element applies to temporal sublayers except for a top-level temporal sublayer in a video sequence.

[0041] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims.

[0042] In the following, embodiments of the invention will be explained in more detail with reference to the accompanying figures and drawings. [Brief explanation of the drawings]

[0043] [Figure 1A] 1 is a block diagram illustrating an example of a video coding system configured to implement embodiments of the present invention. [Figure 1B] FIG. 2 is a block diagram illustrating another example of a video coding system configured to implement embodiments of the present invention. [Figure 2] 1 is a block diagram illustrating an example of a video encoder configured to implement embodiments of the present invention. [Figure 3] 1 is a block diagram illustrating an exemplary structure of a video decoder configured to implement embodiments of the present invention. [Figure 4]FIG. 1 is a block diagram illustrating an example of an encoding device or a decoding device. [Figure 5] FIG. 10 is a block diagram showing another example of an encoding device or a decoding device. [Figure 6] FIG. 10 is a diagram illustrating an example of a raster scan order. [Figure 7] FIG. 1 is a diagram of examples of tiles, slices, and subpictures. [Figure 8] 31 is a block diagram illustrating an exemplary structure of a content supply system 3100 for implementing a content distribution service. [Figure 9] FIG. 2 is a block diagram illustrating the structure of an example terminal device. [Figure 10] FIG. 10 is a diagram illustrating an example of picture division. [Figure 11] FIG. 1 is a diagram illustrating an example of layers and sublayers for scalable video coding. [Figure 12] FIG. 10 is a diagram showing another example of picture division. [Figure 13] FIG. 10 is a diagram showing another example of picture division. [Figure 14] FIG. 2 illustrates a method for decoding a video bitstream according to an embodiment. [Figure 15] FIG. 2 illustrates a method for encoding a video bitstream according to an embodiment. [Figure 16] FIG. 2 illustrates a method for decoding a video bitstream according to an embodiment. [Figure 17] FIG. 2 illustrates a method for encoding a video bitstream according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0044] In the following, the same reference signs, unless otherwise specified, refer to identical or at least functionally equivalent features.

[0045] In the following description, reference is made to the accompanying drawings which form a part of this disclosure and which show, by way of illustration, specific aspects of embodiments of the invention or in which embodiments of the invention may be used. It is understood that embodiments of the invention may be used in other ways and may include structural or logical changes not shown in the drawings. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0046] For example, it is understood that disclosure related to a described method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, when one or more particular method steps are described, a corresponding device may include one or more units, e.g., functional units, for performing the described one or more method steps (e.g., one unit that performs one or more steps, or multiple units that each perform one or more of the steps), even if such one or more units are not explicitly described or shown in a figure. On the other hand, for example, when 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 the one or more units (e.g., one step that performs the function of one or more units, or multiple steps that each perform one or more functions of multiple units), even if such one or more steps are not explicitly described or shown in a figure. Furthermore, it is understood that features of various exemplary embodiments and / or aspects described herein may be combined with each other unless expressly stated otherwise.

[0047] Video coding generally refers to the processing of a sequence of pictures that form a video or a video sequence. Instead of the term "picture," the terms "frame" or "image" may be used synonymously in the field of video coding. Video coding (or generally coding) includes two parts: video encoding and video decoding. Video encoding is performed at the source side and generally involves processing the original video picture (e.g., by compression) to reduce the amount of data needed to represent the video picture (for more efficient storage and / or transmission). Video decoding is performed at the destination side and generally involves the reverse processing compared to the encoder to reconstruct the video picture. Embodiments that refer to "coding" a video picture (or generally pictures) are understood to relate to "encoding" or "decoding" the video picture or respective video sequence. The combination of the encoding and decoding parts is also called a codec (coding and decoding).

[0048] In the case of lossless video coding, the original video picture can be reconstructed (assuming there is no transmission loss or other data loss during storage or transmission), i.e., the reconstructed video picture has the same quality as the original video picture. In the case of lossy video coding, further compression, for example by quantization, is performed to reduce the amount of data representing the video picture, which cannot be perfectly reconstructed at the decoder, i.e., the quality of the reconstructed video picture is lower or worse than the quality of the original video picture.

[0049] Some video coding standards belong to the group of "lossy hybrid video codecs" (i.e., combine spatial and temporal prediction in the sample domain with 2D transform coding for applying quantization in the transform domain). Each picture of a video sequence is generally partitioned into a set of non-overlapping blocks, and coding is generally performed at the block level. In other words, at an encoder, video is generally processed, i.e., encoded, at the block (video block) level, for example, by generating a prediction block using spatial (intra-picture) prediction and / or temporal (inter-picture) prediction, subtracting the prediction block from a current block (the block currently being / to be processed) to obtain a residual block, transforming the residual block, and quantizing the residual block in the transform domain to reduce the amount of data to be transmitted (compression); whereas at a decoder, an inverse process is applied to the coded or compressed block compared to the encoder to reconstruct the current block for representation. Furthermore, the encoder replicates the decoder's processing loop so that both generate the same prediction (eg, intra and inter prediction) and / or reconstruction for processing, i.e., coding, subsequent blocks.

[0050] In the following, embodiments of a video coding system 10, a video encoder 20 and a video decoder 30 are described based on FIGS.

[0051] 1A is a schematic block diagram illustrating an example coding system 10, e.g., video coding system 10 (or coding system 10 for short), that may utilize techniques of the present application. A video encoder 20 (or encoder 20 for short) and a video decoder 30 (or decoder 30 for short) of video coding system 10 illustrate examples of devices that may be configured to perform techniques according to various examples described in the present application.

[0052] As shown in FIG. 1A, coding system 10 includes a source device 12 configured to provide encoded picture data 21 to, for example, a destination device 14 for decoding the encoded picture data 13.

[0053] The source device 12 includes an encoder 20 and may additionally, i.e., 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.

[0054] Picture source 16 may include or be any kind of picture capture device, e.g., a camera for capturing real-world pictures, and / or any kind of picture generation device, e.g., a computer graphics processor for generating computer-animated pictures, or any kind of other device for obtaining and / or providing real-world pictures, computer-generated pictures (e.g., screen content, virtual reality (VR) pictures), and / or any combination thereof (e.g., augmented reality (AR) pictures). Picture source may be any kind of memory or storage for storing any of the above-mentioned pictures.

[0055] To distinguish from the preprocessor 18 and the processing performed by the preprocessing unit 18, the picture or picture data 17 may also be referred to as a raw picture or raw picture data 17.

[0056] The pre-processor 18 is configured to receive (raw) picture data 17 and perform pre-processing on the picture data 17 to obtain a pre-processed picture 19 or pre-processed picture data 19. The pre-processing performed by the pre-processor 18 may include, for example, cropping, color format conversion (e.g., from RGB to YCbCr), color correction, or noise removal. It may be understood that the pre-processing unit 18 may be an optional component.

[0057] Video encoder 20 is configured to receive pre-processed picture data 19 and provide encoded picture data 21 (further details are described below, eg, with reference to FIG. 2).

[0058] 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, e.g., the destination device 14 or any other device, for storage or direct reconstruction.

[0059] The destination device 14 includes a decoder 30 (e.g., a video decoder 30) and may additionally, i.e., optionally, include a communication interface or communication unit 28, a post-processor 32 (or post-processing unit 32), and a display device 34.

[0060] The communications interface 28 of the destination device 14 is configured to receive the encoded picture data 21 (or any further processed version thereof), for example directly from the source device 12 or from any other source, for example a storage device, for example a storage device for encoded picture data, and to provide the encoded picture data 21 to the decoder 30.

[0061] The communication interface 22 and the communication interface 28 may be configured to transmit or receive the encoded picture data 21 or the encoded data 13 via a direct communication link between the source device 12 and the destination device 14, e.g., a direct wired or wireless connection, or via any type of network, e.g., a wired or wireless network or any combination thereof, or any type of private and public network, or any type of combination thereof.

[0062] The communications interface 22 may be configured to process the encoded picture data 21 using any type of transmission encoding or processing, for example, packaging the encoded picture data 21 into a suitable format, e.g., packets, and / or for transmission over a communications link or network.

[0063] The communications interface 28 forming the counterpart of the communications interface 22 may for example be configured to receive the transmitted data and process the transmitted data using any type of corresponding transmission decoding or processing and / or depackaging to obtain the encoded picture data 21.

[0064] Both communication interface 22 and communication interface 28 may be configured as unidirectional communication interfaces, as indicated by the arrows for communication channel 13 in FIG. 1A pointing from source device 12 toward destination device 14, or as bidirectional communication interfaces, and may be configured, for example, to send and receive messages, for example, to set up connections and to confirm and exchange communications links and / or any other information related to data transmission, e.g., transmission of encoded picture data.

[0065] The decoder 30 is configured to receive encoded picture data 21 and provide decoded picture data 31 or decoded pictures 31 (further details are described below, for example, based on Figure 3 or Figure 5).

[0066] Post-processor 32 of destination device 14 is configured to post-process decoded picture data 31 (also called reconstructed picture data), e.g., decoded picture 31, to obtain post-processed picture data 33, e.g., post-processed picture 33. The post-processing performed by post-processing unit 32 may include, e.g., color format conversion (e.g., from YCbCr to RGB), color correction, cropping, or resampling, or any other processing to prepare, e.g., decoded picture data 31, for display by, e.g., display device 34.

[0067] Display device 34 of destination device 14 is configured to receive post-processed picture data 33, for example, to display the picture to a user or viewer. Display device 34 may be or include any type of display for showing the reconstructed picture, e.g., an integrated or external 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.

[0068] 1A depicts source device 12 and destination device 14 as separate devices, embodiments of the devices may include both or both functionality: source device 12 or corresponding functionality and destination device 14 or corresponding functionality. In such embodiments, source device 12 or corresponding functionality and destination device 14 or corresponding functionality may be implemented using the same hardware and / or software or by separate hardware and / or software or any combination thereof.

[0069] As will be clear to those skilled in the art based on the description, the presence and (exact) division of functions of different units or functions within source device 12 and / or destination device 14 shown in FIG. 1A may vary depending on the actual device and application.

[0070] Encoder 20 (e.g., video encoder 20) or decoder 30 (e.g., video decoder 30), or both encoder 20 and decoder 30, may be implemented by processing circuitry shown in FIG. 1B , such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, hardware, dedicated to video coding, or any combination thereof. Encoder 20 may be implemented by processing circuitry 46 to embody various modules discussed in connection with encoder 20 of FIG. 2 and / or any other encoder system or subsystem described herein. Decoder 30 may be implemented by processing circuitry 46 to embody various modules discussed in connection with decoder 30 of FIG. 3 and / or any other decoder system or subsystem described herein. The processing circuitry may be configured to perform various operations discussed below. 5, where the techniques are implemented partially in software, a device may store instructions for the software on a suitable non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Either video encoder 20 and video decoder 30 may be incorporated as part of a combined encoder / decoder (codec) in a single device, for example, as shown in FIG. 1B.

[0071] The source device 12 and the destination device 14 may include any of a wide range of devices, including any type of handheld or fixed device, e.g., a notebook or laptop computer, a mobile phone, a smartphone, a tablet or tablet computer, a camera, a desktop computer, a set-top box, a television, a display device, a digital media player, a video game console, a video streaming device (such as a content service server or content distribution server), a broadcast receiver device, a broadcast transmitter device, etc., and may use no operating system or any type of operating system. In some cases, the source device 12 and the destination device 14 may be capable of wireless communication. Thus, the source device 12 and the destination device 14 may be wireless communication devices.

[0072] In some cases, the video coding system 10 shown in FIG. 1A is merely an example, and the techniques of this disclosure may be applied to video coding situations (e.g., video encoding or video decoding) that do not necessarily involve any data communication between an encoding device and a decoding device. In other examples, data may be retrieved from local memory, streamed over a network, etc. A video encoding device may encode data and store it in memory, and / or a video decoding device may retrieve 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 data to memory and / or retrieve data from memory and decode it.

[0073] For ease of explanation, embodiments of the present invention are described herein with reference to reference software, e.g., High-Efficiency Video Coding (HEVC), or Versatile Video Coding (VVC), the next-generation video coding standard developed by the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Joint Collaboration Team on Video Coding (JCT-VC) of the Motion Picture Experts Group (MPEG). Those skilled in the art will understand that embodiments of the present invention are not limited to HEVC or VVC.

[0074] Encoder and encoding method FIG. 2 shows a schematic block diagram of an exemplary video encoder 20 configured to implement the techniques of the present application. In the example of FIG. 2, the video encoder 20 includes an input 201 (or input interface 201), a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing 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 FIG. 2 may also be referred to as a hybrid video encoder or a video encoder using a hybrid video codec.

[0075] The residual calculation unit 204, the transform processing unit 206, the quantization unit 208, and the mode selection unit 260 may be considered to form a forward signal path of the encoder 20, while the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244, and the intra prediction unit 254 may be considered to form a backward signal path of the video encoder 20, which corresponds to the signal path of a decoder (see video decoder 30 in FIG. 3 ). The inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244, and the intra prediction unit 254 may also be considered to form a “built-in decoder” of the video encoder 20.

[0076] Picture & Picture Division (Picture & Block) Encoder 20 may, for example, be configured to receive via input 201 picture 17 (or picture data 17), e.g., a picture of a sequence of pictures forming a video or a video sequence. The received picture or picture data may also be preprocessed picture 19 (or preprocessed picture data 19). For simplicity, the following description refers to picture 17. Picture 17 may also be referred to as a current picture or a picture to be coded (particularly in video coding, to distinguish the current picture from other pictures, e.g., already coded and / or decoded pictures of the same video sequence, i.e., the video sequence that also includes the current picture).

[0077] A (digital) picture is or can be considered as a two-dimensional array or matrix of samples having intensity values. The samples of the array may also be called pixels (short for picture element) or pels. The number of samples in the horizontal and vertical directions (or axes) of the array or picture defines the size and / or resolution of the picture. For color representation, three color components are generally used, i.e., a picture may be represented or include three sample arrays. In an RBG format or color space, a picture includes corresponding red, green, and blue sample arrays. However, in video coding, each pixel is generally represented in a luminance and chrominance format or color space, e.g., YCbCr, which includes a luminance component denoted by Y (although L may be used instead) and two chrominance components denoted by Cb and Cr. The luminance (or luma for short) component Y represents brightness or gray level intensity (e.g., similar to a grayscale picture), while the two chrominance (or chroma for short) components Cb and Cr represent chromaticity or color information components. Thus, a picture in YCbCr format includes 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 may be converted or transformed to YCbCr format, or vice versa; the process is also known as color transformation or conversion. If a picture is monochrome, the picture may include only a luminance sample array. Thus, a picture may be, for example, an array of luma samples in a monochrome format, or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 color formats.

[0078] An embodiment of video encoder 20 may include a picture partitioning unit (not shown in FIG. 2 ) configured to partition picture 17 into multiple (usually non-overlapping) picture blocks 203. These blocks may also be called root blocks, macroblocks (H.264 / AVC), or coding tree blocks (CTBs) or coding tree units (CTUs) (H.265 / HEVC and VVC). The picture partitioning unit may be configured to use the same block size for all pictures of a video sequence and a corresponding grid defining the block size, or to vary the block size among pictures or subsets or groups of pictures, and to partition each picture into corresponding blocks.

[0079] In further embodiments, the video encoder may be configured to directly receive blocks 203 of picture 17, e.g., one, some, or all of the blocks that form picture 17. Picture blocks 203 may also be referred to as current picture blocks or picture blocks to be coded.

[0080] Similar to picture 17, picture block 203 has smaller dimensions than picture 17, but is also considered or can be considered a two-dimensional array or matrix of samples having intensity values ​​(sample values). In other words, block 203 may include, for example, one sample array (e.g., a luma array for a monochrome picture 17, or a luma or chroma array for a color picture), or three sample arrays (e.g., a luma and two chroma arrays for a color picture 17), or any other number and / or type of array, depending on the applied color format. The number of samples in the horizontal and vertical directions (or axes) of block 203 defines the size of block 203. Thus, a block may be, for example, an MxN (M columns by N rows) array of samples or an MxN array of transform coefficients.

[0081] The embodiment of video encoder 20 shown in FIG. 2 may be configured to encode picture 17 block by block, eg, encoding and prediction is performed for each block 203.

[0082] The embodiment of video encoder 20 shown in FIG. 2 may be further configured to partition and / or encode pictures by using slices (also referred to as video slices), where a picture may be partitioned into or encoded using one or more (generally non-overlapping) slices, each of which may include one or more blocks (e.g., CTUs).

[0083] The embodiment of video encoder 20 shown in FIG. 2 may be further configured to partition and / or encode a picture by using tile groups (also referred to as video tile groups) and / or tiles (also referred to as video tiles), where a picture may be partitioned into or encoded using one or more (generally non-overlapping) tile groups, where each tile group may, for example, include one or more blocks (e.g., CTUs) or one or more tiles, where each tile may, for example, be rectangular in shape and include one or more blocks (e.g., CTUs), e.g., full or fractional blocks.

[0084] Calculating residuals The residual calculation unit 204 may be configured to calculate the residual block 205 (also referred to as the residual 205) based on the picture block 203 and the prediction block 265 (further details about the prediction block 265 are provided later), for example, by subtracting the sample values ​​of the prediction block 265 from the sample values ​​of the picture block 203 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in the sample domain.

[0085] conversion The transform processing unit 206 may be configured to apply a transform, for example, a discrete cosine transform (DCT) or a discrete sine transform (DST), to the sample values ​​of the residual block 205 to obtain transform coefficients 207 in a transform domain. The transform coefficients 207, also referred to as transform residual coefficients, may represent the residual block 205 in the transform domain.

[0086] The transform processing unit 206 may be configured to apply an integer approximation of a DCT / DST, such as the transform specified for H.265 / HEVC. Compared to an orthogonal DCT transform, such an integer approximation is generally scaled by a particular factor. To maintain the norm of the residual blocks processed by the forward and inverse transforms, an additional scaling factor is applied as part of the transform process. The scaling factor is generally selected based on particular constraints, such as the scaling factor being a power of two for shift operations, the bit depth of the transform coefficients, a trade-off between accuracy and implementation cost, etc. For example, a particular scaling factor may be specified for the inverse transform, e.g., by the inverse transform processing unit 212 (and the corresponding inverse transform, e.g., by the inverse transform processing unit 312 in the video decoder 30), and a corresponding scaling factor for the forward transform, e.g., by the transform processing unit 206 of the encoder 20, may be specified accordingly.

[0087] An embodiment of the video encoder 20 (respectively, the transform processing unit 206) may be configured to output transform parameters, e.g., a certain transform or transforms, either as is or encoded or compressed by the entropy coding unit 270, such that the video decoder 30 may receive the transform parameters and use them for decoding.

[0088] quantization The quantization unit 208 may be configured to quantize the transform coefficients 207, for example, by applying scalar quantization or vector quantization, to obtain quantized coefficients 209. The quantized coefficients 209 may also be referred to as quantized transform coefficients 209 or quantized residual coefficients 209.

[0089] The quantization process may reduce the bit depth associated with some or all of the transform coefficients 207. For example, an n-bit transform coefficient may be truncated to an m-bit transform coefficient during quantization, where n is greater than m. The degree of quantization may be modified by adjusting a quantization parameter (QP). For example, with respect to scalar quantization, different scaling may be applied to achieve finer or coarser quantization. A smaller quantization step size corresponds to finer quantization, while a larger quantization step size corresponds to coarser quantization. The applicable quantization step size may be indicated by the quantization parameter (QP). The quantization parameter may, for example, be an index into a predefined set of applicable quantization step sizes. For example, a small quantization parameter may correspond to fine quantization (small quantization step size) and a large quantization parameter may correspond to coarse quantization (large quantization step size), or vice versa. Quantization may include division by a quantization step size, and corresponding and / or inverse dequantization by, for example, the inverse quantization unit 210 may include multiplication by the quantization step size. Some standards, for example, HEVC, embodiments may be configured to determine the quantization step size using a quantization parameter. Generally, the quantization step size may be calculated based on the quantization parameter using a fixed-point approximation of an equation involving division. Additional scaling factors may be introduced for quantization and dequantization to restore the norm of the residual block, which may be modified due to scaling used in the fixed-point approximation of the equation for the quantization step size and the quantization parameter. In one exemplary implementation, the scaling of the inverse transform and dequantization may be combined. Alternatively, customized quantization tables may be used, e.g., signaled from the encoder to the decoder in the bitstream.Quantization is a lossy operation and the loss increases as the quantization step size increases.

[0090] An embodiment of video encoder 20 (respectively, quantization unit 208) may be configured to output a quantization parameter (QP), e.g., as is or encoded by entropy encoding unit 270, such that video decoder 30 may receive and apply the quantization parameter for decoding.

[0091] inverse quantization Inverse quantization unit 210 is configured to apply the inverse quantization of quantization unit 208 to the quantized coefficients to obtain dequantized coefficients 211, e.g., by applying the inverse of the quantization scheme applied by quantization unit 208, based on or using the same quantization step size as quantization unit 208. The dequantized coefficients 211, also referred to as dequantized residual coefficients 211, may correspond to transform coefficients 207—although they are generally not identical to the transform coefficients due to loss due to quantization.

[0092] Inverse transformation The inverse transform processing unit 212 is configured to apply an 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, to obtain a reconstructed residual block 213 (or corresponding dequantized coefficients 213) in the sample domain. The reconstructed residual block 213 may also be referred to as a transform block 213.

[0093] Rebuild The reconstruction unit 214 (e.g., an adder or summator 214) is configured to add the transform block 213 (i.e., the reconstructed residual block 213) to the prediction block 265, for example, by adding the sample values ​​of the reconstructed residual block 213 and the sample values ​​of the prediction block 265—sample by sample—to obtain a reconstructed block 215 in the sample domain.

[0094] filtering The loop filter unit 220 (or "loop filter" 220 for short) is configured to filter the reconstructed block 215 to obtain a filtered block 221, or generally, to filter reconstructed samples to obtain filtered samples. The loop filter unit is configured, for example, to smooth pixel transitions or otherwise improve video quality. 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, for example, a bilateral filter, an adaptive loop filter (ALF), a sharpening filter, a smoothing filter, or a collaborative filter, or any combination thereof. Although the loop filter unit 220 is shown in FIG. 2 as being an in-loop filter, in other configurations, the loop filter unit 220 may be implemented as a post-loop filter. The filtered block 221 may also be referred to as a filtered reconstructed block 221.

[0095] Embodiments of video encoder 20 (respectively, loop filter unit 220) may be configured to output loop filter parameters (e.g., sample adaptive offset information) either as is or encoded by entropy coding unit 270, e.g., such that decoder 30 may receive and apply the same loop filter parameters or respective loop filters for decoding.

[0096] Decoded Picture Buffer The decoded picture buffer (DPB) 230 may be a memory that stores reference pictures or generally reference picture data for encoding video data by the video encoder 20. The DPB 230 may be formed by any of a variety of 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 further be configured to store other already-filtered blocks, e.g., already-reconstructed filtered blocks 221, of the same current picture or a different picture, e.g., an already-reconstructed picture, and may 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), e.g., for inter-prediction. The decoded picture buffer (DPB) 230 may also be configured to store one or more unfiltered reconstructed blocks 215 or generally unfiltered reconstructed samples, for example, if the reconstructed blocks 215 are not filtered by the loop filter unit 220, or to store any other further processed version of the reconstructed blocks or samples.

[0097] 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 obtain original picture data, e.g., original block 203 (current block 203 of current picture 17), and reconstructed picture data, e.g., filtered and / or unfiltered reconstructed samples or blocks of the same (current) picture and / or from one or more already decoded pictures, for example, from the decoded picture buffer 230 or other buffer (e.g., a line buffer, not shown). The reconstructed picture data is used as reference picture data for prediction, e.g., inter prediction or intra prediction, to obtain a prediction block 265 or predictor 265.

[0098] 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 (which does not include partitioning) and generate a corresponding prediction block 265 used for calculating the residual block 205 and reconstructing the reconstructed block 215.

[0099] Embodiments of the mode selection unit 260 may be configured to select a partitioning and prediction mode (e.g., 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 or balances both. 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 the prediction mode that provides the smallest rate-distortion. Terms such as “best,” “minimum,” “optimum,” etc. in this context do not necessarily refer to the overall “best,” “minimum,” “optimum,” etc., but may also refer to satisfying termination or selection criteria such as values ​​above or below a threshold, or other constraints that potentially lead to a “suboptimal selection,” but that reduce complexity and processing time.

[0100] In other words, the partitioning unit 262 may be configured to partition the block 203 into smaller partitions or sub-blocks of the block (which also form blocks) using, for example, quadtree partitioning (QT), binary partitioning (BT), or ternary tree partitioning (TT), or any combination thereof, iteratively, and to perform prediction on, for example, each of the partitions or sub-blocks of the block, wherein the mode selection includes selecting a tree structure of the partitioned block 203, and a prediction mode is applied to each of the partitions or sub-blocks of the block.

[0101] Below, the partitioning (eg, by partitioning unit 260) and prediction processes (by inter-prediction unit 244 and intra-prediction unit 254) performed by exemplary video encoder 20 are described in more detail.

[0102] Division The partitioning unit 262 may partition (or divide) the current block 203 into smaller sections, e.g., smaller blocks of square or rectangular size. These smaller blocks (which may also be called sub-blocks) may be further partitioned into even smaller sections. This is also called tree partitioning or hierarchical tree partitioning; for example, a root block at root tree level 0 (hierarchical level 0, depth 0) may be recursively partitioned, e.g., into two or more blocks at the next lower tree level, e.g., a node at tree level 1 (hierarchical level 1, depth 1), which may again be partitioned into two or more blocks at the next lower level, e.g., tree level 2 (hierarchical level 2, depth 2), and so on, until partitioning is terminated, e.g., because a termination criterion is met, e.g., a maximum tree depth or a minimum block size is reached. Blocks that are not further partitioned are also called leaf blocks or leaf nodes of the tree. A tree that uses a partition into two partitions is called a binary tree (BT), a tree that uses a partition into three partitions is called a ternary tree (TT), and a tree that uses a partition into four partitions is called a quad tree (QT).

[0103] As mentioned above, the term "block" as used herein may refer to a portion of a picture, particularly a square or rectangular portion. For example, in the context of HEVC and VVC, a block may be or correspond to a coding tree unit (CTU), a coding unit (CU), a prediction unit (PU), and a transform unit (TU), and / or a corresponding block, such as a coding tree block (CTB), a coding block (CB), a transform block (TB), or a prediction block (PB).

[0104] For example, a coding tree unit (CTU) could be or include a CTB of luma samples, two corresponding CTBs of chroma samples for a picture with a three-sample arrangement, or a CTB of samples for a picture coded using three separate color planes and a syntax structure used to code a monochrome picture or sample. Correspondingly, a coding tree block (CTB) could be an NxN block of samples for some value of N such that the division of the components into CTBs is a partition. A coding unit (CU) could be or include a coding block of luma samples, two corresponding coding blocks of chroma samples for a picture with a three-sample arrangement, or a coding block of samples for a picture coded using three separate color planes and a syntax structure used to code a monochrome picture or sample. Correspondingly, a coding block (CB) could be an MxN block of samples for some values ​​of M and N such that the division of the CTB into coding blocks is a partition.

[0105] For example, in an HEVC embodiment, a coding tree unit (CTU) may be divided into CUs by using a quadtree structure represented as a coding tree. The decision of whether to code a picture area using inter-picture (temporal) prediction or intra-picture (spatial) prediction is made at the CU level. Each CU may be further divided into one, two, or four PUs according to a PU partition type. Within one PU, the same prediction process is applied, and related information is transmitted to the decoder based on the PU. After obtaining residual blocks by applying a prediction process based on the PU partition type, the CU may be partitioned into transform units (TUs) by another quadtree structure similar to the coding tree for the CU.

[0106] For example, in an embodiment according to the latest video coding standard currently under development, called Versatile Video Coding (VVC), a combined quadtree and binary tree (QTBT) partitioning is used, for example, to partition coding blocks. In the QTBT block structure, a CU may have either a square or rectangular shape. For example, a coding tree unit (CTU) is first partitioned by a quadtree structure. The leaf nodes of the quadtree are further partitioned by a binary tree or a ternary (or triple) tree structure. The leaf nodes of the partitioning tree are called coding units (CUs), and their segmentation is used for prediction and transform processing without any further partitioning. This means that CUs, PUs, and TUs have the same block size in the QTBT coding block structure. In parallel, multi-partitioning, for example, ternary tree partitioning, may be used together with the QTBT block structure.

[0107] In one example, mode select unit 260 of video encoder 20 may be configured to perform any combination of the partitioning techniques described herein.

[0108] As mentioned above, video encoder 20 is configured to determine or select a best or optimal prediction mode from a set of (e.g., predetermined) prediction modes, which may include, for example, intra-prediction modes and / or inter-prediction modes.

[0109] Intra prediction The set of intra prediction modes may include, for example, the 35 different intra prediction modes defined in HEVC, e.g., non-directional modes such as DC (or average) mode and planar mode, or directional modes, or may include, for example, the 67 different intra prediction modes defined for VVC, e.g., non-directional modes such as DC (or average) mode and planar mode, or directional modes.

[0110] The intra prediction unit 254 is configured to generate the intra prediction block 265 using reconstructed samples of neighboring blocks of the same current picture according to an intra prediction mode from a set of intra prediction modes.

[0111] The intra prediction unit 254 (or generally the mode selection unit 260) is further configured to output the intra prediction parameters (or generally information indicating the selected intra prediction mode for the block) to the entropy encoding 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.

[0112] Inter Prediction The set (or possible) inter prediction modes depends on the available reference pictures (i.e., for example, previous at least partially decoded pictures stored in DBP230) as well as other inter prediction 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, for example, a search window area around the area of ​​the current block, and / or whether pixel interpolation, for example, half / semi-pel and / or quarter-pel interpolation, is applied.

[0113] In addition to the prediction modes mentioned above, skip mode and / or direct mode may be applied.

[0114] The inter prediction unit 244 may include a motion estimation (ME) unit and a motion compensation (MC) unit (neither of which are shown in FIG. 2). The motion estimation unit may be configured to receive or obtain, for motion estimation, the picture block 203 (the current picture block 203 of the current picture 17) and the decoded picture 231, or at least one or more already reconstructed blocks, e.g., reconstructed blocks of one or more other / different already decoded pictures 231. For example, a video sequence may include the current picture and the already decoded picture 231, or in other words, the current picture and the already decoded picture 231 may be part of or form a sequence of pictures that form a video sequence.

[0115] The encoder 20 may be configured to, for example, select a reference block from multiple reference blocks of the same or different pictures among multiple other pictures, and provide the reference picture (or reference picture index) and / or an offset (spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block as an inter-prediction parameter to the motion estimation unit. This offset is also called a motion vector (MV).

[0116] The motion compensation unit is configured to obtain, e.g., receive, inter prediction parameters and perform inter prediction based on or using the inter prediction parameters to obtain the inter prediction block 265. The motion compensation performed by the motion compensation unit may include fetching or generating a prediction block based on a motion / block vector determined by motion estimation, possibly performing interpolation with sub-pixel accuracy. Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that may be used to code the picture block. Upon receiving a motion vector for the PU of the current picture block, the motion compensation unit may find the prediction block to which the motion vector points in one of the reference picture lists.

[0117] The motion compensation unit may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding picture blocks of the video slices. In addition to, 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.

[0118] Entropy Coding The entropy coding unit 270 is configured to apply, for example, an entropy coding algorithm or scheme (e.g., a variable length coding (VLC) scheme, a context adaptive VLC scheme (CAVLC), an arithmetic coding scheme, binarization, context adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding, or another entropy coding method or technique) or bypass (uncompressed) to the quantized coefficients 209, the inter-prediction parameters, the intra-prediction parameters, the loop filter parameters, and / or other syntax elements to obtain coded picture data 21 that may be output via an output 272, for example, in the form of coded bitstream 21, such that, for example, video decoder 30 may receive the parameters and use them for decoding. The encoded bitstream 21 may be transmitted to the video decoder 30 or stored in memory for later transmission or retrieval by the video decoder 30 .

[0119] Other structural variations of the video encoder 20 may be used to encode the video stream. For example, a non-transform-based encoder 20 may directly quantize the residual signal for a particular block or frame without a transform processing unit 206. In another implementation, the encoder 20 may have the quantization unit 208 and the inverse quantization unit 210 combined into a single unit.

[0120] Decoder and decoding method 3 shows an example of a video decoder 30 configured to implement the techniques of the present application. The video decoder 30 is configured to receive coded picture data 21 (e.g., coded bitstream 21), e.g., coded by encoder 20, to obtain a decoded picture 331. The coded picture data or bitstream includes information for decoding the coded picture data, e.g., data representing picture blocks of coded video slices (and / or tile groups or tiles) and associated syntax elements.

[0121] 3, decoder 30 includes an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (e.g., summer 314), a loop filter 320, a decoded picture buffer (DBP) 330, a mode application unit 360, an inter prediction unit 344, and an intra prediction unit 354. Inter prediction unit 344 may be or include a motion compensation unit. Video decoder 30, in some examples, may perform a decoding path that is generally the reverse of the encoding path described in connection with video encoder 100 of FIG. 2.

[0122] As described in connection with encoder 20, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, loop filter 220, decoded picture buffer (DPB) 230, inter prediction unit 344, and intra prediction unit 354 are also considered to form a “built-in decoder” of video encoder 20. Accordingly, inverse quantization unit 310 may be functionally identical to inverse quantization unit 110, inverse transform processing unit 312 may be functionally identical to inverse transform processing unit 212, reconstruction unit 314 may be functionally identical to reconstruction unit 214, loop filter 320 may be functionally identical to loop filter 220, and decoded picture buffer 330 may be functionally identical to decoded picture buffer 230. Accordingly, the descriptions given with respect to the respective units and functions of video encoder 20 apply mutatis mutandis to the respective units and functions of video decoder 30.

[0123] Entropy Decoding The entropy decoding unit 304 is configured to parse the bitstream 21 (or generally the coded picture data 21) and, e.g., perform entropy decoding on the coded picture data 21 to obtain, e.g., quantized coefficients 309 and / or decoded coding parameters (not shown in FIG. 3 ), e.g., any or all of inter-prediction parameters (e.g., reference picture indices and motion vectors), intra-prediction parameters (e.g., intra-prediction modes or indices), transform 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 connection with 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 to provide other parameters to other units of the decoder 30. The video decoder 30 may receive syntax elements at the video slice level and / or the video block level. In addition to 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.

[0124] inverse quantization Inverse quantization unit 310 may be configured to receive a quantization parameter (QP) (or information generally related to inverse quantization) and quantized coefficients from encoded picture data 21 (e.g., by parsing and / or decoding by entropy decoding unit 304), and apply inverse quantization to the decoded quantized coefficients 309 based on the quantization parameter to obtain dequantized coefficients 311, which may also be referred to as transform coefficients 311. The inverse quantization process may include using the quantization parameter determined by video encoder 20 for each video block within a video slice (or tile or tile group) to determine the degree of quantization and, similarly, the degree of inverse quantization to be applied.

[0125] Inverse transformation The inverse transform processing unit 312 may be configured to receive the dequantized coefficients 311, also referred to as transform coefficients 311, and apply a transform to the dequantized coefficients 311 to obtain reconstructed residual blocks 213 in the sample domain. The reconstructed residual blocks 213 may also be referred to as transform blocks 313. The transform may be an inverse transform, e.g., an inverse DCT, an inverse DST, an inverse integer transform, or a conceptually similar inverse transform process. The inverse transform processing unit 312 may further be configured to receive transform parameters or corresponding information from the coded picture data 21 (e.g., by parsing and / or decoding, e.g., by entropy decoding unit 304) to determine the transform to apply to the dequantized coefficients 311.

[0126] Rebuild The reconstruction unit 314 (e.g., an adder or summer 314) may be configured to add the reconstructed residual block 313 to the prediction block 365, for example, by adding the sample values ​​of the reconstructed residual block 313 and the sample values ​​of the prediction block 365, to obtain a reconstructed block 315 in the sample domain.

[0127] filtering Loop filter unit 320 (either in the coding loop or after the coding loop) is configured to filter reconstructed block 315 to obtain filtered block 321, e.g., to smooth pixel transitions or otherwise improve video quality. 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, e.g., a bilateral filter, an adaptive loop filter (ALF), a sharpening filter, a smoothing filter, or a collaborative filter, or any combination thereof. Although loop filter unit 320 is shown in FIG. 3 as being an in-loop filter, in other configurations, loop filter unit 320 may be implemented as a post-loop filter.

[0128] Decoded Picture Buffer The decoded video blocks 321 of the picture are then stored in a decoded picture buffer 330, which stores the decoded picture 331 as a reference picture for subsequent motion compensation with respect to other pictures and / or for output on a display, respectively.

[0129] The decoder 30 is configured to output the decoded pictures 311 for presentation or viewing to a user, for example via an output 312.

[0130] prediction The inter prediction unit 344 may be identical to the inter prediction unit 244 (especially the motion compensation unit), and the intra prediction unit 354 may be functionally identical to the inter prediction unit 254, and performs the partitioning or partitioning decision and prediction based on partitioning and / or prediction parameters or respective information received from the encoded picture data 21 (e.g., by analyzing and / or decoding by the entropy decoding unit 304). The mode application unit 360 may be configured to perform prediction (intra or inter prediction) for each block based on the (filtered or unfiltered) reconstructed picture, block, or respective sample to obtain a prediction block 365.

[0131] When a video slice is coded as an intra-coded (I) slice, intra prediction unit 354 of mode application unit 360 is configured to generate a predictive block 365 for a 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, inter prediction unit 344 (e.g., a motion compensation unit) of mode application unit 360 is configured to generate a predictive block 365 for a video block of the current video slice based on the motion vector and other syntax elements received from entropy decoding unit 304. For inter prediction, the predictive block may be generated from one of the reference pictures in one of the reference picture lists. Video decoder 30 may construct the reference frame lists, List 0 and List 1, using a default construction technique based on the reference pictures stored in DPB 330. 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.

[0132] Mode application unit 360 is configured to determine prediction information for video blocks of the current video slice by parsing motion vectors or related information and other syntax elements, and to use the prediction information to generate a predictive block for the current video block being decoded. For example, mode application unit 360 uses some of the received syntax elements to determine the prediction mode (e.g., intra or inter prediction) used to code the video blocks of the video slice, the slice type for inter prediction (e.g., B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists for the slice, motion vectors for each inter-coded video block of the slice, the status of inter prediction for each inter-coded video block of the slice, and other information for decoding 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); e.g., video may be coded using I, P, or B tile groups and / or tiles.

[0133] The embodiment of video decoder 30 shown in FIG. 3 may be configured to partition and / or decode pictures by using slices (also called video slices), where a picture may be partitioned into or decoded using one or more (generally non-overlapping) slices, and each slice may include one or more blocks (e.g., CTUs).

[0134] The embodiment of video decoder 30 shown in FIG. 3 may be configured to partition and / or decode a picture by using tile groups (also referred to as video tile groups) and / or tiles (also referred to as video tiles), where a picture may be partitioned into or decoded using one or more (generally non-overlapping) tile groups, where each tile group may, for example, include one or more blocks (e.g., CTUs) or one or more tiles, where each tile may, for example, be rectangular in shape and may include one or more blocks (e.g., CTUs), e.g., full or fractional blocks.

[0135] Other variations of video decoder 30 may be used to decode encoded picture data 21. For example, decoder 30 may generate an output video stream without loop filtering unit 320. For example, a non-transform-based decoder 30 may directly inverse quantize the residual signal for a particular block or frame without inverse transform processing unit 312. In another implementation, video decoder 30 may have inverse quantization unit 310 and inverse transform processing unit 312 combined into a single unit.

[0136] It should be understood that in the encoder 20 and the 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 clip or shift may be performed on the processing result of the interpolation filtering, motion vector derivation, or loop filtering.

[0137] It should be noted that further operations may be applied to the derived motion vector of the current block (including, but not limited to, control point motion vectors in affine mode, lower-block motion vectors in affine, planar, and ATMVP modes, temporal motion vectors, etc.). For example, the value of a motion vector is constrained to a predetermined 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 equal to 16, the range is -32768 to 32767, and if bitDepth is set 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 sub-blocks in one 8x8 block) are constrained so that the maximum difference between the integer parts of the MVs of the four 4x4 sub-blocks is no more than N pixels, such as no more than 1 pixel. Here, we provide two methods for constraining the motion vectors according to bitDepth.

[0138] Method 1: Delete the overflow MSB (Most Significant Bit) by flowing operation ux = ( mvx+2 bitDepth ) % 2 bitDepth (1) mvx = ( ux >= 2 bitDepth-1 ) ? (ux - 2 bitDepth ) : ux (2) uy = ( mvy+2 bitDepth ) % 2 bitDepth (3) mvy = ( uy >= 2 bitDepth-1 ) ? (uy - 2 bitDepth ) : uy (4) where mvx is the horizontal component of the motion vector of the image block or sub-block, mvy is the vertical component of the motion vector of the image block or sub-block, and ux and uy denote intermediate values.

[0139] For example, if the value of mvx is -32769, after applying equations (1) and (2), the resulting value is 32767. In computer systems, decimal numbers are stored as two's complement numbers. The two's complement of -32769 is 1, 0111, 1111, 1111, 1111 (17 bits), then the MSB is discarded, therefore the resulting two's complement is 0111, 1111, 1111, 1111 (decimal 32767), which is the same as the output by applying equations (1) and (2). ux= ( mvpx + mvdx +2 bitDepth ) % 2 bitDepth (5) mvx = ( ux >= 2 bitDepth-1 ) ? (ux - 2 bitDepth ) : ux (6) uy= ( mvpy + mvdy +2 bitDepth ) % 2 bitDepth (7) mvy = ( uy >= 2 bitDepth-1 ) ? (uy - 2 bitDepth ) : uy (8)

[0140] The operations may be applied during the summation of mvp and mvd as shown in equations (5) to (8).

[0141] Method 2: Remove overflow MSB by clipping the value vx = Clip3(-2 bitDepth-1 , 2 bitDepth-1 -1, vx) vy = Clip3(-2 bitDepth-1 , 2 bitDepth-1 -1, vy) where vx is the horizontal component of the motion vector of the image block or sub-block, vy is the vertical component of the motion vector of the image block or sub-block, x, y, and z correspond to the three input values ​​of the clipping process of MV, respectively, and the definition of the function Clip3 is as follows:

number

[0142] 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 the disclosed embodiments as described herein. In an embodiment, the video coding device 400 may be a decoder, such as the video decoder 30 of FIG. 1A, or an encoder, such as the video encoder 20 of FIG. 1A.

[0143] 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 a memory 460 for storing data. 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 emitting or receiving optical or electrical signals.

[0144] 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), FPGA, ASIC, and DSP. 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 disclosed embodiments described above. For example, the coding module 470 implements, processes, prepares, or provides various coding operations. Thus, the inclusion of the coding module 470 significantly 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.

[0145] Memory 460 may include one or more disks, tape drives, and solid-state drives, and may be used to store programs when such programs are selected for execution, as well as an overflow data storage device for storing instructions and data read during execution of the programs. 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).

[0146] FIG. 5 is a simplified block diagram of an apparatus 500 that may be used as either or both of source device 12 and destination device 14 of FIG. 1, according to an exemplary embodiment.

[0147] Processor 502 of apparatus 500 may be a central processing unit. Alternatively, processor 502 may be any other type of device or devices, existing or later developed, that are capable of manipulating or processing information. While the disclosed implementations may be performed by a single processor, e.g., processor 502, as shown, speed and efficiency advantages may be realized by using two or more processors.

[0148] The memory 504 of the apparatus 500 may, in implementation, be a read-only memory (ROM) device or a random-access memory (RAM) device. Any other suitable type of storage device may be used as the memory 504. The memory 504 may include code and data 506 accessed by the processor 502 using a bus 512. The memory 504 may further include an operating system 508 and application programs 510, which include at least one program that enables the processor 502 to perform the methods described herein. For example, the application programs 510 may include applications 1 through N, further including a video coding application that performs the methods described herein.

[0149] The apparatus 500 may also include one or more output devices, such as a display 518. The display 518, in one example, may be a touch-sensitive display that combines a display with touch-sensing elements operable to sense touch input. The display 518 may be coupled to the processor 502 via the bus 512.

[0150] Although shown here as a single bus, bus 512 of device 500 may be comprised of multiple buses. Additionally, secondary storage 514 may be directly coupled to other components of device 500 or may be accessed over 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 may be implemented in a wide variety of configurations.

[0151] Parameter Set Parameter sets are fundamentally similar and share the same fundamental design goals—namely, bitrate efficiency, error resilience, and providing a system layer interface. HEVC (H.265) has a hierarchy of parameter sets, including video parameter sets (VPSs), sequence parameter sets (SPSs), and picture parameter sets (PPSs), similar to their counterparts in AVC and VVC. Each slice references a single active PPS, SPS, and VPS to access information used to decode the slice. The PPS contains information that applies to all slices in a picture; therefore, all slices in a picture must reference the same PPS. Slices in different pictures are also allowed to reference the same PPS. Similarly, the SPS contains information that applies to all pictures in the same coded video sequence.

[0152] Although the PPS may be different for different pictures, it is common for many or all pictures in a coded video sequence to reference the same PPS. Reusing parameter sets is bitrate efficient because it avoids the need to transmit shared information multiple times. Reusing parameter sets is also loss-robust because it allows the parameter set contents to be carried by some more reliable external communication link or repeated frequently within the bitstream to ensure that the parameter set contents are not lost.

[0153] Scalable Video Coding, Layers, and Video Parameter Sets (VPS) Scalable video coding provides a mechanism for coding video into multiple layers, with each layer representing a quality representation of the same video scene. The base layer (BL) is the lowest quality representation. One or more enhancement layers (EL) may be coded with reference to lower layers to provide improved video quality. Decoding a subset of the layers of a scalably coded video bitstream results in video of lower, but acceptable, quality. This allows for more graceful degradation compared to non-scalable video bitstreams, where a reduction in bitrate generally leads to a greater degradation of video quality.

[0154] There are several types of scalability in scalable video sequences, including temporal scalability, spatial scalability, and quality scalability. Figure 11 provides an example illustrating both spatial and temporal scalability. In Figure 11, two layers are coded at different resolutions. The BL has a lower resolution and the EL has a higher resolution, and spatial scalability is achieved by providing a decoder for decoding either the BL, the EL, or both.

[0155] In addition to spatial scalability, temporal scalability is achieved within the coding layers. In this example, each coding layer is divided into two temporal sublayers, which are labeled by temporal ID 0 and IID 1, respectively. Temporal scalability is achieved by providing for decoding either temporal sublayer 0 (with temporal ID equal to 0) or both sublayers 0 and 1.

[0156] A picture of each layer is assigned a layer ID, e.g., the syntax element nuh_layer_id. A coded layer video sequence (CLVS) is a sequence of pictures with the same value of nuh_layer_id, including, in decoding order, a special coding layer video sequence starting coding picture (CLVSS, e.g., an intra picture) followed by zero or more pictures that are not CLVSS pictures, including all subsequent pictures up to, but not including, any subsequent picture that is a CLVSS picture.

[0157] A coded video sequence (CVS) includes one or more coded layer video sequences (CLVS). In the example of Figure 11, assuming that the first pictures of BL and EL are CLVSS pictures and all other pictures are not CLVSS pictures, this CVS includes two CLVSS.

[0158] Sequence Parameter Set (SPS) An SPS applies to one layer of a coded video sequence and contains parameters that do not change from picture to picture within the coded video sequence.

[0159] In some extreme cases, the SPS may not be used by any picture in the CLVS.

[0160] An SPS may be shared by different CLVSs.

[0161] In the latest VVC specification draft (i.e., http: / / phenix.it-sudparis.eu / jvet / doc_end_user / documents / 19_Teleconference / wg11 / JVET-S0152-v5.zip, for brevity referred to as VVC draft in the following sections), the definition of SPS is as follows: Sequence Parameter Set (SPS): A syntax structure containing zero or more CLV-wide syntax elements determined by the content of syntax elements found in the PPS referenced by syntax elements found in each picture header.

[0162] Please refer to the VVC draft for the definition of the PPS and picture header.

[0163] In particular, the SPS contains information regarding the signaling of the decoded picture buffer (ie, dpb).

[0164] Some parts of the table below show snapshots of some of the dpb signaling within the SPS in VVC.

[0165] Signaling of Decoded Picture Buffer (DPB) Information Decoded Picture Buffer The decoded picture buffer (DPB) is a buffer used to store decoded pictures for reference, e.g., as reference pictures for inter-prediction. In the example disclosed in the VVC draft, the relevant syntax elements of the parameters for DBP in the sequence parameter set (SPS) are highlighted.

[0166] [Table 1]

[0167] sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that the profile_tier_level() and dpb_parameters() syntax structures are present in the SPS, and that the general_hrd_parameters() and ols_hrd_parameters() syntax structures may also be present in the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0 specifies that none of these four syntax structures are present in the SPS.

[0168] When sps_video_parameter_set_id is greater than 0 and there is an OLS containing only one layer with nuh_layer_id equal to the nuh_layer_id of the SPS, or when sps_video_parameter_set_id is equal to 0, the value of sps_ptl_dpb_hrd_params_present_flag is equal to 1.

[0169] An OLS (output layer set) is a set of layers in which one or more layers are designated as output layers. An output layer is a layer of the output layer set that is output.

[0170] The syntax tables for the syntax structures profile_tier_level(), dpb_parameters(), general_hrd_parameters(), and ols_hrd_parameters() can be found in the VVC draft.

[0171] The syntax element sps_max_sublayers_minus1 indicates the number of available temporal sublayers. When the number of available temporal sublayers is greater than 1 (e.g., the value of the syntax element sps_max_sublayers_minus1 is greater than 0), the value of the syntax element sps_sublayer_dpb_params_flag is signaled in the bitstream. The syntax element sps_sublayer_dpb_params_flag indicates whether decoded picture information should be signaled for each available sublayer (when its value is equal to 1) or only for the highest temporal sublayer (when its value is equal to 0). When the value of sps_sublayer_dpb_params_flag is not present, e.g., when only one temporal sublayer exists (the value of sps_max_sublayers_minus1 == 0), the value of sps_max_sublayers_minus1 is inferred to be 0.

[0172] In some examples, the value of the syntax element sps_ptl_dpb_hrd_params_present_flag indicates whether the signaling structure dpb_parameter( ) is signaled within the SPS. When the value of the syntax element sps_ptl_dpb_hrd_params_present_flag is equal to 1, the signaled data structure dpb_parameter( ) is called with the number of available temporal sublayers minus 1 (sps_max_sublayers_minus1) and the flag sps_sublayer_dpb_params_flag as the first and second parameters, respectively.

[0173] In the example, the signaling structure of dpb_parameter( ) in the VVC draft is defined as follows:

[0174] [Table 2]

[0175] The dpb_parameters( ) syntax structure provides information on the DPB size, maximum picture reorder number, and maximum latency for one or more OLSs.

[0176] When the dpb_parameters() syntax structure is included in a VPS, the OLS to which the dpb_parameters() syntax structure applies is specified by the VPS. When the dpb_parameters() syntax structure is included in an SPS, the dpb_parameters() syntax structure applies to an OLS that includes only the layer that is the lowest layer among the layers that reference the SPS, and this lowest layer is an independent layer.

[0177] The value of max_dec_pic_buffering_minus1[ i ] plus 1 specifies the maximum required size of the DPB in picture storage buffer units when Htid is equal to i. The value of max_dec_pic_buffering_minus1[ i ] ranges from 0 to MaxDpbSize - 1, inclusive, where MaxDpbSize is as specified in Section A.4.2. When i is greater than 0, max_dec_pic_buffering_minus1[ i ] is greater than or equal to max_dec_pic_buffering_minus1[ i - 1 ]. When max_dec_pic_buffering_minus1[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_dec_pic_buffering_minus1[ i ] is inferred to be equal to max_dec_pic_buffering_minus1[ maxSubLayersMinus1 ].

[0178] max_num_reorder_pics[ i ] specifies the maximum allowable number of pictures in the OLS that can precede any picture in the OLS in decoding order and follow that picture in output order when Htid is equal to i. The value of max_num_reorder_pics[ i ] is in the range from 0 to max_dec_pic_buffering_minus1[ i ], inclusive. When i is greater than 0, max_num_reorder_pics[ i ] is greater than or equal to max_num_reorder_pics[ i - 1 ]. When max_num_reorder_pics[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_num_reorder_pics[ i ] is inferred to be equal to max_num_reorder_pics[ maxSubLayersMinus1 ].

[0179] max_latency_increase_plus1[ i ] not equal to 0 is used to calculate the value of MaxLatencyPictures[ i ], which specifies the maximum number of pictures in the OLS that can precede any picture in the OLS in output order and follow that picture in decoding order when Htid is equal to i.

[0180] When max_latency_increase_plus1[ i ] is not equal to 0, the value of MaxLatencyPictures[ i ] is specified as follows: MaxLatencyPictures[ i ] = max_num_reorder_pics[ i ] + max_latency_increase_plus1[ i ] - 1 (112) When max_latency_increase_plus1[ i ] is equal to 0, the corresponding limit is not shown. max_latency_increase_plus1[ i ] has values ​​of 0 and 2 32 - 0 to 2 inclusive 32 - 2. When max_latency_increase_plus1[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_latency_increase_plus1[ i ] is inferred to be equal to max_latency_increase_plus1[ maxSubLayersMinus1 ].

[0181] For more detailed information on the syntax elements and variables used to describe the dpb parameters (max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i]), please refer to the VVC draft.

[0182] The dpb_parameters signaling structure is controlled by the value of subLayerInfoFlag and signals either the decoded picture buffer information of one sublayer or the decoded picture information of each sublayer. When the value of subLayerInfoFlag is 0, the decoded picture buffer information of the highest sublayer among the available temporal sublayers is signaled (i=maxSubLayersMinus1). When the value of subLayerInfoFlag is 1, the decoded picture buffer information of each sublayer among the available temporal sublayers is signaled (the value of i ranges from 0 to maxSubLayersMinus1 inclusive).

[0183] Issue with semantics of syntax element sps_sublayer_dpb_params_flag In the VVC draft, the semantics of sps_sublayer_dpb_params_flag are defined as follows: sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure in the SPS. When not present, the value of sps_sub_dpb_params_info_present_flag is inferred to be equal to 0.

[0184] The above semantics has two problems. First, the last statement When not present, the value of sps_sub_dpb_params_info_present_flag is inferred to be equal to 0. sps_sub_dpb_params_info_present_flag is not defined anywhere else, so the last sentence should be corrected to: When not present, the value of sps_sublayer_dpb_params_flag is inferred to be equal to 0.

[0185] Second, the semantics of sps_sublayer_dpb_params_flag is not strict enough, since the range of i in max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i] is not defined. It can be seen from Table 2 that when i is equal to maxSubLayersMinus1 (corresponding to sps_max_sublayers_minus1 in Table 1), the syntax elements max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i] are always signaled, whether sps_sublayer_dpb_params_flag is equal to 0 or 1. sps_sublayer_dpb_params_flag does not control the presence of max_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], and max_latency_increase_plus1[i] in this case, which is inconsistent with the current definition.

[0186] In some examples, the syntax element sps_sublayer_dpb_params_flag is only used as the second parameter of dpb_parameters.

[0187] For the following embodiments, we assume that the typo (first issue) has already been corrected, and the proposed embodiments focus on addressing the second issue: the incorrect semantics of sps_sublayer_dpb_params_flag.

[0188] Embodiment 1 According to the first embodiment, the semantics of sps_sublayer_dpb_params_flag is modified as follows: sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure in the SPS, for i in the range 0 to sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0. When sps_max_sublayers_minus1 is equal to 0, the value of sps_sublayer_dpb_params_flag is inferred to be equal to 0, and max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] are always signaled for the only sublayer that references the SPS.

[0189] In this way, the semantics of sps_sublayer_dpb_params_flag are clarified: Only when two or more sublayers are present (sps_max_sublayers_minus1 is greater than 0), sps_sublayer_dpb_params_flag controls the presence of minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] in the dpb_parameters() syntax structure, for i ranging from 0 to sps_max_sublayers_minus1 - 1. Otherwise (sps_max_sublayers_minus1 is equal to 0), the signaling of max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] is always signaled, regardless of the value of sps_sublayer_dpb_params_flag. Therefore, the semantics may also be modified in embodiment 2 as follows:

[0190] Embodiment 2 sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure in the SPS, for i in the range 0 to sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0. When sps_max_sublayers_minus1 is equal to 0, the value of sps_sublayer_dpb_params_flag is inferred to be equal to 1, and max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] are always signaled for the only sublayer that references the SPS.

[0191] Or, as shown in embodiment 3, even remove the inference rule for the value of sps_sublayer_dpb_params_flag.

[0192] Embodiment 3 sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure within the SPS, for i in the range from 0 to sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0. When sps_max_sublayers_minus1 is equal to 0, max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] are always signaled for the only sublayer that references the SPS.

[0193] Or, as shown in embodiment 4, provide some explanation when sps_max_sublayers_minus1 is equal to 0.

[0194] Embodiment 4 sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure in the SPS, for i in the range 0 to sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0. When sps_max_sublayers_minus1 is equal to 0, the value of sps_sublayer_dpb_params_flag has no meaning and max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] are always signaled for the only sublayer that references the SPS.

[0195] Correction of Idea 1 using Embodiments 1 to 4 The data structure dpb_parameter() may be called not only in the SPS but also in the VPS. Below is a snapshot of the VPS where dpb_parameter() is called:

[0196] [Table 3]

[0197] Specify the number of dpb_parameters() syntax structures in the VPS.

[0198] vps_default_ptl_dpb_hrd_max_tid_flag equal to 1 specifies that the syntax elements vps_ptl_max_tid[ i ], vps_dpb_max_tid[ i ], and vps_hrd_max_tid[ i ] are not present and are inferred to be equal to the default value vps_max_sublayers_minus1. vps_default_ptl_dpb_hrd_max_tid_flag equal to 0 specifies that the syntax elements vps_ptl_max_tid[ i ], vps_dpb_max_tid[ i ], and vps_ptl_max_tid[ i ] are present. When not present, the value of vps_default_ptl_dpb_hrd_max_tid_flag is inferred to be equal to 1.

[0199] For a detailed description of vps_ptl_max_tid[ i ] and vps_hrd_max_tid[ i ], please refer to the VVC draft.

[0200] vps_dpb_max_tid[ i ] specifies the TemporalId of the representation of the highest sublayer for which DPB parameters may exist in the i-th dpb_parameters() syntax structure in the VPS. The value of vps_dpb_max_tid[ i ] is in the range 0 to vps_max_sublayers_minus1, inclusive. When not present, the value of vps_dpb_max_tid[ i ] is inferred to be equal to vps_max_sublayers_minus1. and vps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ ], max_num_reorder_pics[ ], and max_latency_increase_plus1[ ] syntax elements in the dpb_parameters() syntax structure in the VPS. When not present, vps_sub_dpb_params_info_present_flag is inferred to be equal to 0.

[0201] The semantics of vps_sublayer_dpb_params_present_flag suffer from the same problems as the semantics of sps_sublayer_dpb_params_flag described above.

[0202] The sizes of the syntax element arrays max_dec_pic_buffering_minus1[], max_num_reorder_pics[], and max_latency_increase_plus1[] are not semantically defined. It can be seen from Table 2 that when there is only one sublayer (corresponding to vps_dpb_max_tid[ i ] in Table 4 equal to 0), the syntax elements max_dec_pic_buffering_minus1[], max_num_reorder_pics[], and max_latency_increase_plus1[] are always signaled, whether vps_sublayer_dpb_params_present_flag is equal to 0 or 1. The vps_sublayer_dpb_params_present_flag does not control the presence of max_dec_pic_buffering_minus1[], max_num_reorder_pics[], and max_latency_increase_plus1[] in this case, which is inconsistent with the current definition.

[0203] Embodiment 9 In one example, the semantics of vps_sublayer_dpb_params_present_flag is modified as follows: vps_sublayer_dpb_params_present_flag is used to control the presence of the max_dec_pic_buffering_minus1[ j ], max_num_reorder_pics[ j ], and max_latency_increase_plus1[ j ] syntax elements in the dpb_parameters() syntax structure in the VPS, for j in the range from 0 to vps_dpb_max_tid[ i ] - 1, inclusive, when vps_dpb_max_tid[ i ] in the VPS is greater than 0. When not present, vps_sub_dpb_params_info_present_flag is inferred to be equal to 0. It is noted that to avoid confusion with i in vps_dpb_max_tid[ i ], j rather than i is used to specify the range of the syntax element arrays max_dec_pic_buffering_minus1[ ], max_num_reorder_pics[ ], and max_latency_increase_plus1[ ].

[0204] Remarks, Problem 2 and corresponding solutions, dependentFlag, etc. When inter-prediction is performed, the reference pictures can be decoded images from the same layer or reference pictures from lower layers. In the latter case, the reference pictures of the lower layers are called inter-layer reference pictures (ILRPs), and the lower layers containing one or more ILRPs are called reference (or dependent) layers.

[0205] To support inter-layer prediction, some intermediate variables are used according to the syntax elements signaled by the VPS. For example, in Equation 37 of the VVC draft, the derivation process of the variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] is defined as follows: The variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] are derived as follows: for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0; j <= vps_max_layers_minus1; j++ ) { dependencyFlag[ i ][ j ] = vps_direct_ref_layer_flag[ i ][ j ] for( k = 0; k < i; k++ ) if( vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] ) dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0, d = 0, r = 0; j <= vps_max_layers_minus1; j++ ) { (37) if( vps_direct_ref_layer_flag[ i ][ j ] ) { DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 } if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j } NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }

[0206] A dependencyFlag[i][j] equal to 1 specifies that the layer with index j is a reference layer for the layer with index i. A dependencyFlag[i][j] equal to 0 specifies that the layer with index j is not a reference layer for the layer with index i.

[0207] The dependency between a layer with index i and its reference layer j can be direct or indirect. If the jth layer is a direct dependent layer of the ith layer, the dependency is signaled in the VPS using the syntax element vps_direct_ref_layer_flag[i][j] for i ranging from 0 to j and j ranging from 0 to i-1, as shown in Table 4, where syntax elements irrelevant to the present invention are removed.

[0208] [Table 4]

[0209] The syntax table above shows how VPS signals dependencies between layers when some layers are not independent layers.

[0210] vps_max_layers_minus1 represents the maximum allowed number of layers in each CVS that references the VPS. Layer dependency information is signaled only from the second lowest layer (i.e., i=1), and if some layers are not independent layers, this is indicated by the syntax element vps_all_independent_layers_flag.

[0211] vps_all_independent_layers_flag equal to 1 specifies that all layers specified by the VPS are coded independently without using inter-layer prediction. vps_all_independent_layers_flag equal to 0 specifies that one or more of the layers specified by the VPS may use inter-layer prediction. When not present, the value of vps_all_independent_layers_flag is inferred to be equal to 1.

[0212] In VVC, the lowest layer (i.e., corresponding to vps_independent_layer_flag

[0000] ) is always an independent layer. Therefore, the syntax element vps_independent_layer_flag[ i ] is signaled from the second lowest layer (i.e., vps_independent_layer_flag

[0001] ), and its semantics are quite simple and clear.

[0213] vps_independent_layer_flag[ i ] equal to 1 specifies that the layer with index i does not use inter-layer prediction. vps_independent_layer_flag[ i ] equal to 0 specifies that the layer with index i may use inter-layer prediction and that the syntax element vps_direct_ref_layer_flag[ i ][ j ] is present in the VPS, for j in the range of 0 to i - 1, inclusive. When not present, the value of vps_independent_layer_flag[ i ] is inferred to be equal to 1.

[0214] Only when a layer is not an independent layer (i.e., vps_independent_layer_flag[ i ] is 0) are its direct dependent layers signaled and indicated by vps_direct_ref_layer_flag[ i ][ j ] for j ranging from 0 to i-1.

[0215] The semantics of vps_direct_ref_layer_flag[ i ][ j ] are defined as follows: vps_direct_ref_layer_flag[ i ][ j ] equal to 0 specifies that the layer with index j is not a direct reference layer of the layer with index i. vps_direct_ref_layer_flag[ i ][ j ] equal to 1 specifies that the layer with index j is a direct reference layer of the layer with index i. When vps_direct_ref_layer_flag[ i ][ j ] is not present for i and j in the range from 0 to vps_max_layers_minus1, inclusive, vps_direct_ref_layer_flag[ i ][ j ] is inferred to be equal to 0. When vps_independent_layer_flag[ i ] is equal to 0, there is at least one value of j in the range from 0 to i - 1, inclusive, such that the value of vps_direct_ref_layer_flag[ i ][ j ] is equal to 1.

[0216] When a layer is a dependent layer (i.e., its vps_independent_layer_flag[ i ] is equal to 0), the constraint in the semantics of vps_direct_ref_layer_flag[ i ][ j ] specifies that at least one of its subordinate layers j in the range 0 to i-1, inclusive, is a reference layer for layer i.

[0217] In the case of an indirect dependency, it can occur when layer i directly depends on layer k (k < i), and layer k further depends on layer j (j < k). In such a case, the layer with index i depends on layer j, and the corresponding dependencyFlag[i][j] is equal to 1.

[0218] Issues in the derivation process: Because a layer can only depend on lower layers, the loop that searches for dependent lower layers j in the derivation process can be simplified: it does not need to loop over all layers in the VPS, but only over layers lower than the current layer i.

[0219] Embodiment 5 In one example, the derivation process for the variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] is modified as follows: The variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] are derived as follows: for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0 ; j < i ; j++ ) { dependencyFlag[ i ][ j ] = vps_direct_ref_layer_flag[ i ][ j ] for( k = 0; k < i; k++ ) if( vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] ) dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0, d = 0, r = 0; j <i; j++ ) { (37) if( vps_direct_ref_layer_flag[ i ][ j ] ) { DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 } if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j } NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }

[0220] Embodiment 6 In another example, the derivation process for the variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] is modified as follows: The variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] are derived as follows: for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0 ; j < i ; j++ ) { dependencyFlag[ i ][ j ] = vps_direct_ref_layer_flag[ i ][ j ] for( k = j+1; k < i; k++ ) if( vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] ) dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0, d = 0, r = 0; j < i; j++ ) { (37) if( vps_direct_ref_layer_flag[ i ][ j ] ) { DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 } if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j } NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }

[0221] Embodiment 7 In another example, the derivation process for the variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] is modified as follows: The variables dependencyFlag[ i ][ j ], NumDirectRefLayers[ i ], DirectRefLayerIdx[ i ][ d ], NumRefLayers[ i ], RefLayerIdx[ i ][ r ], and LayerUsedAsRefLayerFlag[ j ] are derived as follows: for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0; j <= vps_max_layers_minus1; j++ ) { dependencyFlag[ i ][ j ] = vps_direct_ref_layer_flag[ i ][ j ] for( k = j+1; k < i; k++ ) if( vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] ) dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i = 0; i <= vps_max_layers_minus1; i++ ) { for( j = 0, d = 0, r = 0; j <= vps_max_layers_minus1; j++ ) { (37) if( vps_direct_ref_layer_flag[ i ][ j ] ) { DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 } if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j } NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }

[0222] Only the loop for( k = 0; k < i; k++ ) is modified to for( k = j+1; k < i; k++ ).

[0223] Embodiment 8 Correspondingly, the semantics of vps_direct_ref_layer_flag[ i ][ j ] are changed as follows: vps_direct_ref_layer_flag[i][j] equal to 0 specifies that the layer with index j is not a direct reference layer of the layer with index i. vps_direct_ref_layer_flag[i][j] equal to 1 specifies that the layer with index j is a direct reference layer of the layer with index i. When vps_direct_ref_layer_flag[i][j] is not present for i in the range of 1 to vps_max_layers_minus1, inclusive, and jj in the range of 0 to i-1, inclusive, vps_direct_ref_layer_flag[i][j] is inferred to be equal to 0. When vps_independent_layer_flag[ i ] is equal to 0, there exists at least one value of j in the range from 0 to i − 1, inclusive, such that the value of vps_direct_ref_layer_flag[ i ][ j ] is equal to 1. There are several other variable syntax elements that express dependencies similar to vps_direct_ref_layer_flag[i][j], and their scopes change in the same way.

[0224] According to the above description, a method for decoding a video bitstream and a method for encoding a video bitstream are provided herein. Correspondingly, an apparatus for decoding a (coded) video bitstream and an apparatus for decoding a video bitstream are provided herein.

[0225] 14 shows a method for decoding a video bitstream, performed by a decoding device, where a sequence parameter set SPS is coded in the video bitstream and includes syntax elements to be applied to the video sequence. The method includes step 1410 of obtaining (e.g., by parsing the bitstream) a value of a first syntax element (e.g., sps_ptl_dpb_hrd_params_present_flag from the SPS), where the value of the first syntax element is used to specify whether a decoded picture buffer DPB parameters syntax structure is present in the SPS. The method further includes step 1420 of obtaining (e.g., by parsing the bitstream) a value of a second syntax element (e.g., sps_sublayer_dpb_params_flag as described above) from the SPS when it is determined (determined) that the value of the first syntax element specifies that a DPB parameter syntax structure is present in the SPS, wherein the value of the second syntax element is used to specify the presence of a DPB syntax element (e.g., one of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] as described in detail above) in the DPB parameter syntax structure, and the DPB syntax element applies to temporal sublayers except the topmost temporal sublayer in the video sequence.

[0226] It is noted that the bit stream may be obtained by a wireless network or a wired network. The bit stream may be 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, microwave, WIFI, Bluetooth, LTE, or 5G.

[0227] A bitstream may be a sequence of bits in the form of a network abstraction layer (NAL) unit stream or byte stream that forms a representation of a sequence of access units (AUs) that form one or more coded video sequences (CVSs).

[0228] In a particular example, the format of the bitstream specifies the relationship between a Network Abstraction Layer (NAL) unit stream and a byte stream, and either the Network Abstraction Layer (NAL) unit stream or the byte stream is referred to as a bitstream.

[0229] A bitstream can be in one of two formats: a NAL unit stream format or a byte stream format. The NAL unit stream format is conceptually the more "basic" type. The NAL unit stream format contains a sequence of syntax structures called NAL units. This sequence is ordered in decoding order. There are constraints imposed on the decoding order (and content) of the NAL units in a NAL unit stream.

[0230] The format of the byte stream may be constructed from the format of the NAL unit stream by ordering the NAL units in decoding order and prefixing each NAL unit with a start code prefix and zero or more zero-valued bytes to form a stream of bytes. The format of the NAL unit stream may be extracted from the format of the byte stream by locating unique start code prefix patterns within this stream of bytes.

[0231] 15 shows a method for encoding a video bitstream, performed by an encoding device, in which a sequence parameter set (SPS) is encoded into the video bitstream and includes syntax elements to be applied to the video sequence. The method includes step 1510 of determining the presence of a decoded picture buffer DPB parameters syntax structure in the SPS. Based on the determination of the presence of the DPB parameters syntax structure in the SPS, a value of a first syntax element (e.g., sps_ptl_dpb_hrd_params_present_flag from the above description) is coded into the SPS (1520), and the value of the first syntax element is used to specify whether the DPB parameters syntax structure is present in the SPS. 15 further includes step 1530 of determining the presence of a DPB syntax element (e.g., one of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] in accordance with the detailed description above) in the DPB parameter syntax structure, where the DPB syntax element applies to a temporal sublayer other than the topmost temporal sublayer in the video sequence. Based on the determination of the presence of the DPB syntax element in the DPB parameter syntax structure, a value of a second syntax element (e.g., sps_sublayer_dpb_params_flag in accordance with the description above) is coded into the SPS (1540), where the value of the second syntax element is used to specify the presence of the DPB syntax element in the DPB parameter syntax structure.

[0232] The above-described methods may be embedded in a video decoding device or a video encoding device (which generates a bitstream), respectively, as described below.

[0233] 16, a video decoding device 1600 provided herein according to an embodiment includes an obtaining unit 1610 (e.g., including a parser) and a determining unit 1620. As shown in FIG. 17, a video encoding device 1700 provided herein according to an embodiment includes a determining unit 1710 and an encoding unit 1720.

[0234] The obtaining unit 1610 included in the video decoding device 1600 shown in Figure 16 is configured to obtain a value of a first syntax element (e.g., sps_ptl_dpb_hrd_params_present_flag according to the above description) from the SPS, and the value of the first syntax element is used to specify whether a decoded picture buffer DPB parameters syntax structure is present in the SPS coded into the video bitstream. The determining unit 1620 included in the video decoding device 1600 shown in Figure 16 is configured to determine whether the value of the first syntax element specifies that the DPB parameters syntax structure is present in the SPS. Further, the obtaining unit 1610 is configured to obtain a value of a second syntax element (e.g., sps_sublayer_dpb_params_flag as described above) from the SPS when it determines (is determined) that the value of the first syntax element specifies that a DPB parameter syntax structure exists in the SPS, and the value of the second syntax element is used to specify the presence of a DPB syntax element (e.g., one of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] as described in detail above) in the DPB parameter syntax structure, and the DPB syntax element applies to temporal sublayers except the topmost temporal sublayer in the video sequence.

[0235] The determining unit 1710 included in the video encoding device 1700 shown in Figure 17 is configured to determine the presence of a decoded picture buffer DPB parameters syntax structure in the SPS. The encoding unit 1720 included in the video encoding device 1700 shown in Figure 17 is configured to encode, based on the determination of the presence of the DPB parameters syntax structure in the SPS, a value of a first syntax element (e.g., sps_ptl_dpb_hrd_params_present_flag according to the above description) into the SPS, where the value of the first syntax element is used to specify whether the DPB parameters syntax structure is present in the SPS. Furthermore, when (e.g., only when) the determining unit 1710 determines that a DPB parameter syntax structure exists in the SPS, the determining unit 1710 is configured to determine the presence of a DPB syntax element (e.g., one of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] according to the detailed description above) in the DPB parameter syntax structure, where the DPB syntax element applies to a temporal sublayer except for the highest temporal sublayer in the video sequence. Furthermore, the encoding unit 1720 is configured to encode, based on the determination of the presence of the DPB syntax element in the DPB parameter syntax structure, a value of a second syntax (e.g., sps_sublayer_dpb_params_flag according to the description above) element into the SPS, where the value of the second syntax element is used to specify the presence of the DPB syntax element in the DPB parameter syntax structure.

[0236] The video decoding device 1600 shown in Figure 16 may be or may be included by the decoder 30 shown in Figures 1A, 1B, and 3 and the video decoder 3206 shown in Figure 9. Furthermore, the decoding device 1700 may be included by the video coding device 400 shown in Figure 4, the device 500 shown in Figure 5, and the terminal device 3106 shown in Figure 8. The encoding device 1700 shown in Figure 17 may be the encoder 20 shown in Figures 1A, 1B, and 3, or may be included by such an encoder 20. Furthermore, the encoding device 1700 may be included by the video coding device 400 shown in Figure 4, the device 500 shown in Figure 5, and the capture device 3102 shown in Figure 8.

[0237] In particular, the SPS contains information regarding the signaling of sub-pictures.

[0238] Some parts of the table below have download links as follows: http: / / phenix.it-sudparis.eu / jvet / doc_end_user / documents / 17_Brussels / wg11 / JVET-Q2001-v13.zip 1 shows a snapshot of part of the signaling of sub-pictures within an SPS in ITU JVET-Q2001-v13, which will be referred to as VVC Draft 8 for brevity in the remainder of this application.

[0239] [Table 5A] [Table 5B]

[0240] Some syntax elements in the SPS signal the position information and control flags of each sub-picture. The position information of the i-th sub-picture includes: subpic_ctu_top_left_x[ i ], which indicates the horizontal component of the top-left coordinate of subpicture i within the picture, or subpic_ctu_top_left_y[ i ], which indicates the vertical component of the top-left coordinate of subpicture i within the picture, or subpic_width_minus1[ i ], which indicates the width of subpicture i within the picture, or subpic_height_minus1[ i ] indicates the height of subpicture i within the picture.

[0241] Some syntax elements, for example sps_num_subpics_minus1, indicate the number of subpictures in a picture.

[0242] Partitioning a picture into CTUs, slices, tiles, and subpictures Partitioning pictures into CTUs A picture is divided into a sequence of coding tree units (CTUs). The term CTU is sometimes used interchangeably with CTB (coding tree block). In examples, the term CTU is the same as the definition of CTU in ITU-T H.265. For a picture with a three-sample arrangement, a CTU contains an NxN block of luma samples and two corresponding blocks of chroma samples. Figure 6 shows an example of a picture divided into CTUs. The sizes of the CTUs must be the same except for CTUs at the picture boundaries (where incomplete CTUs may exist).

[0243] Dividing a picture into tiles In some examples, when tiles are enabled, a picture is divided into rectangular groups of CTUs separated by vertical and / or horizontal boundaries. The vertical and horizontal tile boundaries intersect the picture from down and from the left picture boundary to the right picture boundary, respectively. Indication information related to the location of the horizontal and vertical tile boundaries is coded into the bitstream.

[0244] Figure 7 illustrates the partitioning of a picture into nine tiles, in this example the tile boundaries are indicated by thick dashed lines.

[0245] When there are two or more tiles that divide a picture vertically, the scan order of the CTUs is changed relative to the raster scan order of the CTUs within the picture. The CTUs are scanned according to the following rules: 1. The tiles are scanned in raster scan order from left to right and top to bottom, which is called tile scan order. This means that starting with the top left tile, first all tiles in the same tile row are scanned from left to right. Then, starting with the first tile in the second tile row (the one below), all tiles in the second tile row are scanned from left to right. This process is repeated until all tiles have been scanned. 2. For a tile, the CTUs within the tile are scanned in raster scan order. For each CTU row, the CTUs are scanned from left to right, and the CTU row is scanned from top to bottom. Figure 7 illustrates the scan order of the CTUs within a tile, where the numbers corresponding to the CTUs indicate the scan order.

[0246] Tiles provide a partitioning of a picture in such a way that each tile can be decoded independently of other tiles of the same picture, where decoding refers to entropy, residual, and predictive decoding. Furthermore, tiles allow a picture to be partitioned into regions of similar size. Thus, tiles of a picture can be processed in parallel with each other, which is preferable in a multi-core processing environment where each processing core is identical to each other.

[0247] The terms processing order and scan order are used in this application as follows. Processing refers to the encoding or decoding of CTUs in an encoder or decoder. Scan order relates to the indexing of a particular partition within a picture. CTUs are indexed in ascending order within a picture according to a specified scan order. The CTU scan order within a tile refers to how CTUs within the tile are indexed, which may not be the same as the order in which the CTUs are processed (i.e., the processing order).

[0248] Partitioning a picture into slices The concept of slices provides a partitioning of a picture in such a way that each slice is decodable independently of other slices of the same picture, where decoding refers to entropy, residual, and predictive decoding. The difference with tiles is that slices can have any shape, not necessarily rectangular (more flexible in terms of partitioning possibilities), and the purpose of the partitioning of slices is not parallelism, but packet size matching and error resilience in a transmission environment.

[0249] A slice may contain a complete picture or a portion of a picture. In ITU-T H.265, a slice contains consecutive CTUs of a picture in processing order. A slice is identified by a starting CTU address, which is signaled in a slice header or a picture parameter set or other unit. In an example, when a slice is required to contain an integer number of tiles, the slice may be identified by a starting tile address.

[0250] In VVC Draft 8, a slice contains an integer number of tiles, or an integer number of contiguous CTU rows within a tile of a picture. As a result, vertical slice boundaries are also vertical tile boundaries. It is possible that horizontal slice boundaries are not tile boundaries, but horizontal CTU boundaries may be contained within a tile; for example, when a tile is divided into multiple rectangular slices, each slice contains an integer number of contiguous complete CTU rows within the tile.

[0251] In some examples, there are two slice modes: raster scan slice mode and rectangular slice mode. In raster scan slice mode, a slice contains a sequence of tiles in a raster scan of tiles of a picture. In rectangular slice mode, a slice contains several tiles that collectively form a rectangular area of ​​the picture, or a slice contains several consecutive rows of CTUs of one tile that collectively form a rectangular area of ​​the picture. The tiles in a rectangular slice are scanned in tile raster scan order within the rectangular area corresponding to the slice.

[0252] All slices of a picture collectively form a complete picture, i.e., every CTU of a picture is contained in one of the slices of the picture. Similar rules apply to tiles and subpictures.

[0253] Partitioning a picture into subpictures A subpicture may be a rectangular section of a picture. A subpicture can be an entire picture or a portion of a picture. A subpicture is a partition of a picture in such a way that each subpicture is decodable independently of other subpictures in the entire video sequence. In VVC Draft 8, when the indication of subpic_treated_as_pic_flag[i] is true for subpicture i (e.g., the value of subpic_treated_as_pic_flag[i] is 1), then that subpicture i is decodable independently of other subpictures in the entire video sequence.

[0254] The difference between a sub-picture and a tile or slice is that a sub-picture produces an independently decodable video sequence. For tiles and slices, independent decoding is performed within a single picture of a video sequence.

[0255] In VVC Draft 8, a subpicture contains one or more slices that collectively encompass a rectangular region of the picture. Thus, the boundaries of each subpicture are always slice boundaries, and the boundaries of each vertical subpicture are always vertical tile boundaries.

[0256] FIG. 10 provides examples of tiles, slices, and subpictures.

[0257] 8, the picture is partitioned into 216 CTUs, 4 tiles, 4 slices, and 3 subpictures. The value of sps_num_subpics_minus1 is 2, and the position-related syntax elements have the following values: Regarding subpicture 0, subpic_ctu_top_left_x

[0000] is not signaled and is inferred to be 0. subpic_ctu_top_left_y

[0000] is not signaled and is inferred as 0. ·subpic_width_minus1

[0000] , value is 8. ·subpic_height_minus1

[0000] , value is 11. Regarding subpicture 1, ·subpic_ctu_top_left_x

[0001] , value is 9. ·subpic_ctu_top_left_y

[0001] , the value is 0. ·subpic_width_minus1

[0001] , value is 8 ·subpic_height_minus1

[0001] , value is 5. Regarding subpicture 2, ·subpic_ctu_top_left_x

[0002] , value is 9. ·subpic_ctu_top_left_y

[0002] , value is 6. subpic_width_minus1

[0002] is not signaled and is inferred as 8. · subpic_height_minus1

[0002] is not signaled and is inferred as 5.

[0258] Signaling of Decoded Picture Buffer (DPB) Information Decoded Picture Buffer The decoded picture buffer (DPB) is a buffer used to store decoded pictures for reference, e.g., as reference pictures for inter-prediction. In an example disclosed in the VVC draft (e.g., ITU JVET-Q2001-v13), relevant syntax elements of parameters related to DBPs in a sequence parameter set (SPS) are highlighted.

[0259] [Table 6]

[0260] sps_max_sublayers_minus1 plus 1 specifies the maximum number of temporal sublayers that may exist in each CLVS that references an SPS. The value of sps_max_sublayers_minus1 lies in the range 0 to vps_max_sublayers_minus1, inclusive.

[0261] sps_sublayer_dpb_params_flag is used to control the presence of the max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and max_latency_increase_plus1[ i ] syntax elements in the dpb_parameters() syntax structure in the SPS. When not present, the value of sps_sub_dpb_params_info_present_flag is inferred to be equal to 0.

[0262] sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that the profile_tier_level() and dpb_parameters() syntax structures are present in the SPS, and that the general_hrd_parameters() and ols_hrd_parameters() syntax structures may also be present in the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0 specifies that none of these four syntax structures are present in the SPS. The value of sps_ptl_dpb_hrd_params_present_flag is equal to vps_independent_layer_flag[ GeneralLayerIdx[ nuh_layer_id ] ].

[0263] The syntax element sps_max_sublayers_minus1 indicates the number of available temporal sublayers. When the number of available temporal sublayers is greater than 1 (e.g., the value of the syntax element sps_max_sublayers_minus1 is greater than 0), the value of the syntax element sps_sublayer_dpb_params_flag is signaled in the bitstream, since the syntax element sps_sublayer_dpb_params_flag indicates whether decoded picture information should be signaled for each available sublayer (when its value is equal to 1) or only for the highest temporal sublayer (when its value is equal to 0). When the value of sps_sublayer_dpb_params_flag is absent, e.g., when only one temporal sublayer exists (the value of sps_max_sublayers_minus1 == 0), the value of sps_max_sublayers_minus1 is inferred to be 0.

[0264] In some examples, the value of the syntax element sps_ptl_dpb_hrd_params_present_flag indicates whether the signaling structure dpb_parameter( ) is signaled within the SPS. When the value of the syntax element sps_ptl_dpb_hrd_params_present_flag is equal to 1, the signaled data structure dpb_parameter( ) is called with the number of available temporal sublayers minus 1 (sps_max_sublayers_minus1) and the flag sps_sublayer_dpb_params_flag as the first and second parameters, respectively.

[0265] In an example, the signaling structure of dpb_parameter( ) in the VVC draft (eg, ITU JVET-Q2001-v13) is defined as follows:

[0266] [Table 7]

[0267] The dpb_parameters( ) syntax structure provides information about the DPB size, maximum picture reordering, and maximum latency for one or more OLSs. (Output Layer Set (OLS): A layer set consisting of a specified set of layers, where one or more layers in the layer set are designated as output layers.)

[0268] When the dpb_parameters() syntax structure is included in a VPS, the OLS to which the dpb_parameters() syntax structure applies is specified by the VPS. When the dpb_parameters() syntax structure is included in an SPS, the dpb_parameters() syntax structure applies to an OLS that includes only the layer that is the lowest layer among the layers that reference the SPS, and this lowest layer is an independent layer.

[0269] The value of max_dec_pic_buffering_minus1[ i ] plus 1 specifies the maximum required size of the DPB in picture storage buffer units when Htid is equal to i. The value of max_dec_pic_buffering_minus1[ i ] ranges from 0 to MaxDpbSize - 1, inclusive, where MaxDpbSize is as specified in Section A.4.2. When i is greater than 0, max_dec_pic_buffering_minus1[ i ] is greater than or equal to max_dec_pic_buffering_minus1[ i - 1 ]. When max_dec_pic_buffering_minus1[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_dec_pic_buffering_minus1[ i ] is inferred to be equal to max_dec_pic_buffering_minus1[ maxSubLayersMinus1 ].

[0270] max_num_reorder_pics[ i ] specifies the maximum allowable number of pictures in the OLS that can precede any picture in the OLS in decoding order and follow that picture in output order when Htid is equal to i. The value of max_num_reorder_pics[ i ] is in the range from 0 to max_dec_pic_buffering_minus1[ i ], inclusive. When i is greater than 0, max_num_reorder_pics[ i ] is greater than or equal to max_num_reorder_pics[ i - 1 ]. When max_num_reorder_pics[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_num_reorder_pics[ i ] is inferred to be equal to max_num_reorder_pics[ maxSubLayersMinus1 ].

[0271] max_latency_increase_plus1[ i ] not equal to 0 is used to calculate the value of MaxLatencyPictures[ i ], which specifies the maximum number of pictures in the OLS that can precede any picture in the OLS in output order and follow that picture in decoding order when Htid is equal to i.

[0272] When max_latency_increase_plus1[ i ] is not equal to 0, the value of MaxLatencyPictures[ i ] is specified as follows: MaxLatencyPictures[ i ] = max_num_reorder_pics[ i ] + max_latency_increase_plus1[ i ] - 1 (7-111) When max_latency_increase_plus1[ i ] is equal to 0, the corresponding limit is not shown. max_latency_increase_plus1[ i ] has values ​​of 0 and 2 32 - 0 to 2 inclusive 32 - 2. When max_latency_increase_plus1[ i ] does not exist for i in the range 0 to maxSubLayersMinus1 - 1, inclusive, because subLayerInfoFlag is equal to 0, max_latency_increase_plus1[ i ] is inferred to be equal to max_latency_increase_plus1[ maxSubLayersMinus1 ].

[0273] The dpb_parameters signaling structure is controlled by the value of subLayerInfoFlag and signals either the decoded picture buffer information of one sublayer or the decoded picture information of each sublayer. When the value of subLayerInfoFlag is 0, the decoded picture buffer information of the highest sublayer among the available temporal sublayers is signaled (i=maxSubLayersMinus1). When the value of subLayerInfoFlag is 1, the decoded picture buffer information of each sublayer among the available temporal sublayers is signaled (the value of i ranges from 0 to maxSubLayersMinus1 inclusive).

[0274] In some examples, the syntax element sps_sublayer_dpb_params_flag is only used as the second parameter of dpb_parameters.

[0275] Embodiment 10 According to the tenth embodiment, the value of the syntax element sps_sublayer_dpb_params_flag is coded in the bitstream based on the value of the syntax element sps_ptl_dpb_hrd_params_present_flag as follows:

[0276] [Table 8]

[0277] In this embodiment, when the value of sps_max_sublayers_minus1 is greater than 0 and the value of sps_ptl_dpb_hrd_params_present_flag is equal to 0, the value of the syntax element sps_sublayer_dpb_params_flag does not need to be coded in the bitstream.

[0278] Embodiment 11 According to the eleventh embodiment, the value of the syntax element sps_sublayer_dpb_params_flag is coded in the bitstream based on the value of the syntax element sps_ptl_dpb_hrd_params_present_flag as follows:

[0279] [Table 9]

[0280] In this embodiment, when the value of sps_max_sublayers_minus1 is greater than 0 and the value of sps_ptl_dpb_hrd_params_present_flag is equal to 0, the value of the syntax element sps_sublayer_dpb_params_flag does not need to be coded in the bitstream. Furthermore, the syntax element is restructured with a clearer design. The syntax element sps_ptl_dpb_hrd_params_present_flag is raised to command the signaling of both the syntax element sps_sublayer_dpb_params_flag and the signaling structure dpb_parameters().

[0281] Embodiment 12 According to the twelfth embodiment, the value of the syntax element sps_sublayer_dpb_params_flag is coded in the bitstream based on the value of the syntax element sps_ptl_dpb_hrd_params_present_flag as follows:

[0282] [Table 10]

[0283] Correspondingly, the signaling structure of dpb_parameters is modified as follows:

[0284] [Table 11]

[0285] In this embodiment, when the value of sps_max_sublayers_minus1 is greater than 0 and the value of sps_ptl_dpb_hrd_params_present_flag is equal to 0, the value of the syntax element sps_sublayer_dpb_params_flag does not need to be coded into the bitstream. Compared with embodiment 11, the signaling structure of dpb_parameter( ) is signaled from the first sublayer to the highest sublayer, indicated by the parameters firstSubLayer and maxSubLayersMinus1, respectively. The selection of the first sublayer is left out of dpb_parameter( ). The semantics of sps_sublayer_dpb_params_flag is thus clearer.

[0286] In an example, as disclosed in the VVC draft (e.g., ITU JVET-Q2001-v13), there are two modes for slices: raster scan slice mode and rectangular slice mode. However, according to the current definition, a slice can be in either raster scan mode or rectangular mode.

[0287] The definition of a slice is explained as follows: A slice consists of an integer number of complete tiles or an integer number of contiguous complete CTU rows within a picture tile. As a result, each vertical slice boundary is always also a vertical tile boundary. The horizontal boundary of a slice is not a tile boundary, but may consist of a horizontal CTU boundary within the tile; this occurs when a tile is divided into multiple rectangular slices, each of which consists of an integer number of contiguous complete CTU rows within the tile.

[0288] Two modes of slicing are supported: raster scan slice mode and rectangular slice mode. In raster scan slice mode, a slice contains a sequence of complete tiles in a raster scan of the tiles of the picture. In rectangular slice mode, a slice contains either several complete tiles that collectively form a rectangular area of ​​the picture, or several contiguous complete CTU rows of one tile that collectively form a rectangular area of ​​the picture. The tiles in a rectangular slice are scanned in tile raster scan order within the rectangular area corresponding to the slice.

[0289] The only constraint on a raster scan slice is that it "contains a complete tile sequence of raster scan tiles of a picture." For example, as shown in Figure 12, there are only two tiles and one slice in a picture. This slice can be in either raster scan slice mode or rectangular slice mode. This can lead to confusion between the two modes of the slice.

[0290] Embodiment 13 It is proposed to further restrict the definition of a raster scan slice as follows: In raster scan slice mode, a slice comprises a complete sequence of tiles in a raster scan of tiles of a picture, and the picture contains at least one slice that forms a non-rectangular shape.

[0291] For example, with this definition of a raster scan slice, the picture shown in FIG. 13 is a raster scan slice, but the picture shown in FIG. 12 can only use the rectangular slice mode.

[0292] The signaling regarding the tile structure is modified accordingly.

[0293] In one example, the signaling of tile information within a PPS is as follows:

[0294] [Table 12]

[0295] no_pic_partition_flag equal to 1 specifies that picture partitioning is not applied to each picture that references a PPS. 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.

[0296] It is a requirement of bitstream conformance that the value of no_pic_partition_flag be the same for all PPSs referenced by coded pictures in the CLVS.

[0297] When the value of sps_num_subpics_minus1 + 1 is greater than 1, it is a requirement for bitstream compliance that the value of no_pic_partition_flag not be equal to 1.

[0298] pps_log2_ctu_size_minus5 plus 5 specifies the luma coding tree block size of each CTU. pps_log2_ctu_size_minus5 is equal to sps_log2_ctu_size_minus5.

[0299] The value of num_exp_tile_columns_minus1 plus 1 specifies the number of tile column widths explicitly provided. The value of num_exp_tile_columns_minus1 is in the range 0 to PicWidthInCtbsY - 1, inclusive. When no_pic_partition_flag is equal to 1, the value of num_exp_tile_columns_minus1 is inferred to be equal to 0.

[0300] The value of num_exp_tile_rows_minus1 plus 1 specifies the number of tile row heights explicitly provided. The value of num_exp_tile_rows_minus1 is in the range 0 to PicHeightInCtbsY - 1, inclusive. When no_pic_partition_flag is equal to 1, the value of num_tile_rows_minus1 is inferred to be equal to 0.

[0301] The value of tile_column_width_minus1[ i ] plus 1 specifies the width of the i-th tile column in units of CTBs, for i in the range 0 to num_exp_tile_columns_minus1 - 1, inclusive. 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 in the range 0 to PicWidthInCtbsY - 1, inclusive. When not present, a value of tile_column_width_minus1

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

[0302] The value of tile_row_height_minus1[ i ] plus 1 specifies the height of the i-th tile row in CTBs, for i in the range 0 to num_exp_tile_rows_minus1 - 1, inclusive. tile_row_height_minus1[ num_exp_tile_rows_minus1 ] is used to derive the height of tile rows with indices 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 0 to PicHeightInCtbsY - 1, inclusive. When not present, a value of tile_row_height_minus1

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

[0303] rect_slice_flag equal to 0 specifies that the tiles in each slice are in raster scan order and slice information is not signaled in the PPS. rect_slice_flag equal to 1 specifies that the tiles in each slice cover a rectangular area of ​​the picture and slice information is signaled in the PPS. When not present, rect_slice_flag is inferred to be equal to 1. When subpic_info_present_flag is equal to 1, the value of rect_slice_flag is equal to 1.

[0304] single_slice_per_subpic_flag equal to 1 specifies that each subpicture consists of only one rectangular slice. single_slice_per_subpic_flag equal to 0 specifies that each subpicture may consist of one or more rectangular slices. 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. When not present, the value of single_slice_per_subpic_flag is inferred to be equal to 0. [Ed. (GJS): Consider renaming or otherwise clarifying this flag to avoid the interpretation that it is only relevant when there are more than one subpicture in each picture.]

[0305] When the number of tiles in a picture is greater than 1, the flag rect_slice_flag is parsed from the bitstream, and the value of rect_slice_flag indicates whether the picture uses rectangular slice mode (when the value is equal to 1) or raster scan slice mode (when the value is equal to 0).

[0306] Correspondingly, in the slice header

[0307] [Table 13]

[0308] picture_header_in_slice_header_flag equal to 1 specifies that PH syntax structures are present in the slice header. picture_header_in_slice_header_flag equal to 0 specifies that PH syntax structures are not present in the slice header.

[0309] It is a requirement for bitstream compliance that the value of picture_header_in_slice_header_flag be the same for all coded slices in a CLVS.

[0310] It is a requirement for bitstream compliance that there are no VCL NAL units with nal_unit_type equal to PH_NUT in the CLVS when picture_header_in_slice_header_flag equals 1 for a coded slice.

[0311] When picture_header_in_slice_header_flag is equal to 0, all coded slices in the current picture have picture_header_in_slice_header_flag equal to 0 and the current PU has a PH NAL unit.

[0312] slice_subpic_id specifies the subpicture ID of the subpicture that contains the slice. If slice_subpic_id is present, the value of the variable CurrSubpicIdx is derived so that SubpicIdVal[ CurrSubpicIdx ] is equal to slice_subpic_id. Otherwise (slice_subpic_id is not present), CurrSubpicIdx is derived to be equal to 0. The length of slice_subpic_id is sps_subpic_id_len_minus1 + 1 bits.

[0313] slice_address specifies the slice address of the slice. When not present, the value of slice_address is inferred to be equal to 0. When rect_slice_flag is equal to 1 and NumSlicesInSubpic[CurrSubpicIdx] is equal to 1, the value of slice_address is inferred to be equal to 0.

[0314] If rect_slice_flag is equal to 0, the following applies: - The slice address is the raster scan tile index. - The length of slice_address is Ceil( Log2( NumTilesInPic ) ) bits. - The value of slice_address is in the range 0 to NumTilesInPic - 1, inclusive.

[0315] Otherwise (rect_slice_flag is equal to 1), the following applies: - The slice address is the sub-picture level slice index of the slice. - The length of slice_address is Ceil( Log2( NumSlicesInSubpic[ CurrSubpicIdx ] ) ) bits. - The value of slice_address is in the range 0 to NumSlicesInSubpic[CurrSubpicIdx] - 1, inclusive.

[0316] It is a requirement for a bitstream to be compliant that the following constraints apply: - If rect_slice_flag is equal to 0 or subpic_info_present_flag is equal to 0, the value of slice_address shall not be equal to the value of slice_address of any NAL unit of any other coded slice of the same coded picture. Otherwise, the pair of values ​​of slice_subpic_id and slice_address is not equal to the pair of values ​​of slice_subpic_id and slice_address of a NAL unit of any other coded slice of the same coded picture. The shape of the slices of the picture is such that each CTU, when decoded, has its entire left and top boundaries consisting of the picture boundaries or of the boundaries of an already decoded CTU.

[0317] sh_extra_bit[ i ] may be equal to 1 or 0. Decoders conforming to this version of the specification ignore the value of sh_extra_bit[ i ]; the value does not affect the decoder's conformance to the profile specified in this version of the specification.

[0318] The value of num_tiles_in_slice_minus1 plus 1, when present, specifies the number of tiles in the slice. The value of num_tiles_in_slice_minus1 is in the range 0 to NumTilesInPic - 1, inclusive.

[0319] In the PPS and slice headers, the following modifications to the above signaling mechanism are proposed:

[0320] [Table 14]

[0321] [Table 15]

[0322] In particular, the following embodiments are also provided herein (in new enumerations):

[0323] 1. A method of coding implemented by a decoding or encoding device, comprising: obtaining a bitstream, wherein a sequence parameter set SPS is coded into the bitstream; obtaining a value of a first syntax element sps_max_sublayers_minus1 according to the bitstream, wherein the value of the first syntax element sps_max_sublayers_minus1 is used to indicate a maximum number of temporal sub-layers present in a coded layer video sequence CLVS that references an SPS; obtaining a value of a second syntax element sps_ptl_dpb_hrd_params_present_flag according to the bitstream, wherein the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is used to indicate whether a decoded picture buffer DPB parameters syntax structure (e.g., dpb_parameters) is present in the SPS; parsing a value of a third syntax element sps_sublayer_dpb_params_flag from the bitstream when the value of the first syntax element sps_max_sublayers_minus1 is greater than a first default value (e.g., the first default value is equal to 0) and when the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is equal to a second default value (e.g., the second default value is equal to 1), wherein the value of the third syntax element sps_sublayer_dpb_params_flag is a value between 0 and sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0; The method includes the steps of: using the buffer buffering method to control the presence of max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and / or max_latency_increase_plus1[ i ], for i in the range of 1 to 1.

[0324] 2. The method of embodiment 1, further comprising the step of setting the value of the third syntax element sps_sublayer_dpb_params_flag to a third default value (e.g., the third default value is equal to 0 or 1) when the value of the first syntax element sps_max_sublayers_minus1 is less than or equal to the first default value or when the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is not equal to the second default value.

[0325] 3. The method of embodiment 1 or 2, wherein the value of a third syntax element sps_sublayer_dpb_params_flag is coded in the SPS.

[0326] 4. A method of coding implemented by a decoding device or an encoding device, comprising: obtaining a bitstream, wherein a sequence parameter set SPS is coded into the bitstream; obtaining a value of a first syntax element sps_max_sublayers_minus1 according to the bitstream, wherein the value of the first syntax element sps_max_sublayers_minus1 is used to specify a maximum number of temporal sub-layers present in a coded layer video sequence CLVS that references an SPS; obtaining a value of a second syntax element sps_ptl_dpb_hrd_params_present_flag according to the bitstream, wherein the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is used to specify whether a decoded picture buffer DPB parameters syntax structure (e.g., dpb_parameters) is present in the SPS; determining whether the value of a second syntax element sps_ptl_dpb_hrd_params_present_flag is equal to a second default value (e.g., the second default value is equal to 1); when it is determined that the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is equal to the second default value, determining whether the value of the first syntax element sps_max_sublayers_minus1 is greater than the first default value (e.g., the first default value is equal to 0); When it is determined that the value of the first syntax element sps_max_sublayers_minus1 is greater than a first default value (e.g., the first default value is equal to 0), parsing the value of a third syntax element sps_sublayer_dpb_params_flag from the bitstream, wherein the value of the third syntax element sps_sublayer_dpb_params_flag is used to control the presence of syntax elements (e.g., max_dec_pic_buffering_minus1[ i ], max_num_reorder_pics[ i ], and / or max_latency_increase_plus1[ i ] for i in the range from 0 to sps_max_sublayers_minus1 - 1, inclusive, when sps_max_sublayers_minus1 is greater than 0).

[0327] 5. The method of embodiment 4, further comprising the step of setting the value of the third syntax element sps_sublayer_dpb_params_flag to a third default value (e.g., the third default value is equal to 0 or 1) when it is determined that the value of the first syntax element sps_max_sublayers_minus1 is less than or equal to the first default value or when it is determined that the value of the second syntax element sps_ptl_dpb_hrd_params_present_flag is not equal to the second default value.

[0328] 6. The method of embodiment 4 or 5, in which the value of the third syntax element sps_sublayer_dpb_params_flag is coded to the SPS (in other examples, the value of the third syntax element sps_sublayer_dpb_params_flag is coded to the picture parameter set PPS, or the value of the third syntax element sps_sublayer_dpb_params_flag is coded to the video parameter set VPS).

[0329] 7. The method of any one of embodiments 1 to 6, wherein the value of the first syntax element is coded into a picture parameter set PPS, or the value of the first syntax element is coded into a video parameter set VPS (in another example, the value of the second syntax element is coded into a picture parameter set PPS, or the value of the second syntax element is coded into a video parameter set VPS).

[0330] 8. The method of any one of embodiments 1 to 7, wherein when sps_max_sublayers_minus1 is equal to 0, max_dec_pic_buffering_minus1

[0000] , max_num_reorder_pics

[0000] , and max_latency_increase_plus1

[0000] are always signaled for the only sublayer that references the SPS.

[0331] 9. A method of coding implemented by a decoding device or an encoding device, comprising: determining an indirect reference layer with index j of a layer with index i from only at least one layer with an index less than i; when inter-layer prediction is enabled for the current picture, obtaining a reference picture for the current picture in an indirect reference layer having an index j; 10. A method comprising predicting a current picture using a reference picture from an indirect reference layer having index j.

[0332] 10. The method of embodiment 9, wherein the step of determining an indirect reference layer of a layer having index i includes determining that only among at least one layer having an index smaller than i and greater than j, there exists a layer having index k that is a direct reference of the layer having index i, and the indirect reference layer having index j is a reference layer of the direct reference layer having index k.

[0333] 11. The method of embodiment 9, wherein the step of determining an indirect direct reference layer of a layer having index i includes determining that, among at least one layer having an index smaller than i, there exists a layer having index k that is a direct reference of the layer having index i, and determining that the indirect reference layer having index j is a reference layer of the direct reference layer having index k.

[0334] 12. A method of coding implemented by a decoding device or an encoding device, comprising: determining an indirect reference layer having index j of the layer having index i when determining that only among at least one layer having an index smaller than i and larger than j, there exists a layer having index k that is a direct reference layer of the layer having index i, wherein the layer having index j is a reference layer of the direct reference layer having index k; when inter-layer prediction is enabled for the current picture, obtaining a reference picture for the current picture in an indirect reference layer having an index j; 10. A method comprising predicting a current picture using a reference picture from an indirect reference layer having index j.

[0335] 13. A method of coding implemented by a decoding device or an encoding device, comprising: obtaining a bitstream, wherein a picture parameter set (PPS) is coded into the bitstream; obtaining a number NumTileColumns of tile columns of the current picture according to the bitstream (e.g., the current picture includes at least one slice that forms a non-rectangular shape); obtaining the number NumTileRows of tile rows of the current picture according to the bitstream; obtaining a value for the variable NumTilesInPic according to the number of tile columns NumTileColumns and the number of tile rows NumTileRows; A method comprising the step of parsing the value of the syntax element rect_slice_flag from the bitstream when the value of the variable NumTilesInPic is greater than a preset value (for example, the preset value is 3), wherein the value of the syntax element rect_slice_flag is used to specify whether slice information is signaled within the PPS.

[0336] 14. The method of embodiment 13, further comprising the step of setting the value of the syntax element rect_slice_flag to a fourth default value (e.g., the fourth default value is equal to 1) when the value of the variable NumTilesInPic is less than or equal to a preset value.

[0337] 15. The method of embodiment 13 or 14, wherein the value of the variable NumTilesInPic is equal to NumTileColumns * NumTileRows.

[0338] 16. A method according to any one of embodiments 13 to 15, further comprising the step of parsing the value of the slice address slice_address of the current slice from the bitstream when the value of the syntax element rect_slice_flag is equal to a fifth default value (for example, the fifth default value is equal to 0) and when the value of the variable NumTilesInPic is greater than a preset value, wherein the current slice is included in the current picture.

[0339] 17. The method of embodiment 16, wherein the value of the slice address is coded in the slice header of the current slice.

[0340] 18. The method of any one of embodiments 13 to 17, further comprising the step of obtaining the number of tiles included in the current slice, num_tiles_in_slice_minus1, when the value of the syntax element rect_slice_flag is equal to a fifth default value and when the value of the variable NumTilesInPic is greater than a preset value.

[0341] 19. The method of embodiment 18, wherein the number of tiles, num_tiles_in_slice_minus1, is coded in the slice header of the current slice.

[0342] 20. A decoder (30) including processing circuitry for implementing the method of any one of embodiments 1 to 19.

[0343] 21. A computer program product comprising a program code for performing the method according to any one of embodiments 1 to 19 when the program code is run on a computer or processor.

[0344] 22. One or more processors; and a non-transitory computer-readable storage medium coupled to the processor and storing programming for execution by the processor, the programming, when executed by the processor, configuring the decoder to perform the method of any one of embodiments 1 to 19.

[0345] 23. A non-transitory computer-readable medium carrying program code that, when executed by a computing device, causes the computing device to perform the method of any one of embodiments 1 to 19.

[0346] The following is a description of the application of the encoding and decoding methods shown in the above embodiments and the systems that use them.

[0347] 8 is a block diagram showing a content supply system 3100 for realizing a content distribution service. The 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. The communication link 3104 may include, but is not limited to, WIFI, Ethernet, cable, wireless (3G / 4G / 5G), USB, or any type of combination thereof.

[0348] The capture device 3102 may generate data and encode the data according to the encoding method described 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. The capture device 3102 may include, but is not limited to, a camera, a smartphone or smart pad, 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, a video encoder 20 included in the capture device 3102 may actually perform the video encoding process. When the data includes audio (i.e., voice), an 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 the encoded video data are not multiplexed. The capture device 3102 delivers the encoded audio data and the encoded video data separately to the terminal device 3106 .

[0349] In the content supply system 3100, the terminal device 3106 receives and plays the encoded data. The terminal device 3106 can be a device having data reception and restoration capabilities, such as a smartphone or smart pad 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, capable of decoding the above-mentioned encoded data. For example, the terminal device 3106 may include the above-mentioned destination device 14. When the encoded data includes video, the video decoder 30 included in the terminal device is prioritized to perform video decoding. When the encoded data includes audio, the audio decoder included in the terminal device is prioritized to perform audio decoding processing.

[0350] For terminal devices with a display, such as a smartphone or smart pad 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 provide 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, an external display 3126 is contacted to receive and show the decoded data.

[0351] When each device in this system performs encoding or decoding, the picture encoding device or picture decoding device shown in the above embodiments may be used.

[0352] 9 is a diagram illustrating an example structure of the terminal device 3106. After the terminal device 3106 receives a stream from the capture device 3102, a protocol progression unit 3202 analyzes the transmission protocol of the stream. The protocol includes, but is 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 kind of combination thereof, etc.

[0353] After the protocol progression unit 3202 processes the stream, a stream file is generated. The file is output to the demultiplexing unit 3204. The demultiplexing unit 3204 can separate the multiplexed data into encoded audio data and encoded video data. As mentioned above, in some practical scenarios, for example, in a video conference 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 the audio decoder 3208 without passing through the demultiplexing unit 3204.

[0354] The demultiplexing process generates a video elementary stream (ES), an audio ES, and optionally subtitles. A video decoder 3206, which includes the video decoder 30 described in the above embodiment, decodes the video ES using the decoding method shown in the above embodiment to generate video frames and supplies this data to a 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, the video frames may be stored in a buffer (not shown in FIG. 9) before supplying them to the synchronization unit 3212. Similarly, the audio frames may be stored in a buffer (not shown in FIG. 9) before supplying them to the synchronization unit 3212.

[0355] The synchronization unit 3212 synchronizes video and audio frames and provides the video / audio to a 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 the coded audio and visual data as well as timestamps for the delivery of the data stream itself.

[0356] If subtitles are included in the stream, the subtitle decoder 3210 decodes the subtitles, synchronizes the subtitles with the video and audio frames, and provides the video / audio / subtitles to the video / audio / subtitle display 3216.

[0357] The present invention is not limited to the above-mentioned system, and either the picture encoding device or the picture decoding device of the above-mentioned embodiments may be incorporated into other systems, for example, a system of an automobile.

[0358] 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 division of real values ​​are defined. The numbering and counting rules generally start from 0; for example, "first" is equivalent to number 0, "second" is equivalent to number 1, and so on.

[0359] 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 y Exponentiation. Specifies x to the yth power. In other contexts, such notation is used to write superscripts that are not intended to be interpreted as powers. / Integer division with result truncation towards zero. For example, 7 / 4 and -7 / -4 round down to 1, and -7 / 4 and 7 / -4 round down to -1. ÷ Used to represent division in mathematical equations where truncation or rounding is not intended.

number

number

[0360] Logical operators The following logical operators are defined as follows: x && y The Boolean logic "intersection" of x and y x || y Boolean logic "union" of x and y Boolean logic "negation" x ? y : zIf x is true or not equal to 0, evaluates to the value y, otherwise evaluates to the value z.

[0361] Relational operators The following relational operators are defined as follows: > Greater than >= Greater than or equal to < Less than <= Less than or equal to == Equal to != Not equal to

[0362] When a relational operator is applied to a syntax element or variable that has been assigned the value "na" (not applicable), the value "na" is treated as a distinct value for the syntax element or variable. The value "na" is not considered equal to any other value.

[0363] Bitwise Operators The following bitwise operators are defined as follows: & Bitwise "and". When operating on integer arguments, operates on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0. Bitwise "logical or". When operating on integer arguments, operates on the two's complement representation of the integer values. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0. ^ Bitwise "exclusive or". When operating on integer arguments, operates on the two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0. x >> y Arithmetic right shift of y bits of the two's complement representation of an integer x. 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 a value equal to the MSB of x before the shift operation. x << y Arithmetic left shift of y bits of the two's complement representation of an integer x. 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.

[0364] Assignment operator The following arithmetic operators are defined as follows. = Assignment operator ++ Increment, i.e., x++ is equivalent to x = x + 1, and when used as an array index, the value of the variable is evaluated before the increment operation. -- Decrement, i.e., x-- is equivalent to x = x - 1, and when used as an array index, the value of the variable is evaluated before the decrement operation. += Increment by the specified amount, i.e., x += 3 is equivalent to x = x + 3, and x += (-3) is equivalent to x = x + (-3). -= Decrement by the specified amount, i.e., x -= 3 is equivalent to x = x - 3, and x -= (-3) is equivalent to x = x - (-3).

[0365] Range notation The following notations are used to specify a range of values. x = y..z x takes integer values from y to z, including y and z, assuming x, y, and z are integer values and z is greater than y.

[0366] Mathematical functions The following mathematical functions are defined.

Number

number

number

number

number

number

number

[0367] Operation precedence When precedence within an expression is not made explicit using parentheses, the following rules apply: - Operations with higher precedence are evaluated before any operations with lower precedence. - Operations of equal precedence are evaluated in order from left to right.

[0368] The table below specifies the precedence of operations from highest to lowest, with higher positions in the table indicating higher precedence.

[0369] With respect to operators that are also used in the C programming language, the precedence used herein is the same as that used in the C programming language.

[0370] [Table 16]

[0371] Text description of logical operations In the text, in the following form: if( condition 0 ) Statement 0 else if( condition1 ) Statement 1 ... else / * Comment giving information about remaining conditions * / Statement n A statement of logical operation, mathematically written in the form: may be written as follows: As follows... / ...the following applies: - If condition 0, then statement 0 - Otherwise, if condition 1, then statement 1 - ... - otherwise (comment conveying information about the remaining conditions), statement n

[0372] Each "if ..., otherwise ..., then ..., otherwise" statement in the text is introduced by "as follows ..." or "...the following applies" immediately followed by "if ..., then ...". The final condition of an "if ..., otherwise ..., then ..., otherwise ..." is always "otherwise ...". Alternately inserted "if ..., otherwise ..., then ..., otherwise ..." statements can be identified by matching the "as follows ..." or "...the following applies" with the closing "otherwise ...".

[0373] In the text, in the following form: if( condition0a && condition0b ) Statement 0 else if( condition 1a || condition 1b ) Statement 1 ... else Statement n A statement of logical operation, mathematically written in the form: may be written as follows: As follows... / ...the following applies: - Statement 0 if all of the following conditions are true: - Condition 0a - Condition 0b - Otherwise, if one or more of the following conditions are true, then statement 1 - Condition 1a - Condition 1b - ... - otherwise, statement n

[0374] In the text, in the following form: if( condition 0 ) Statement 0 if( condition1 ) Statement 1 A statement of logical operation, mathematically written in the form: may be written as follows: If condition 0, then statement 0 If condition 1, then statement 1

[0375] While embodiments of the present invention have been described primarily in terms of video coding, it should be noted that embodiments of coding system 10, encoder 20, and decoder 30 (and correspondingly, system 10), as well as other embodiments described herein, may also be configured for processing or coding of still pictures, i.e., processing or coding of individual pictures independent of any preceding or subsequent pictures, similar to video coding. Generally, when picture processing coding is limited to a single picture 17, only inter prediction units 244 (encoder) and 344 (decoder) may not be available. All other functions (also called tools or technologies) of the video encoder 20 and the video decoder 30, such as residual calculation 204 / 304, transform 206, quantization 208, inverse quantization 210 / 310, (inverse) transform 212 / 312, partitioning 262 / 362, intra prediction 254 / 354, and / or loop filter 220, 320, and entropy coding 270, and entropy decoding 304, may equally be used for processing still pictures.

[0376] For example, embodiments of the encoder 20 and decoder 30 and the functionality described herein in connection with the encoder 20 and decoder 30 may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted over a communication medium as one or more instructions or code and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium such as a data storage medium, or a communication medium, which includes any medium that facilitates transfer of a computer program from one place to another, for example via a communication protocol. Thus, generally, a computer-readable medium may correspond to (1) a tangible computer-readable storage medium that is non-transitory or (2) a communication medium such as a signal or carrier wave. A 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, code, and / or data structures for implementing the techniques described in this disclosure. A computer program product may include a computer-readable medium.

[0377] By way of example, and not 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 medium 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 properly termed a computer-readable medium. 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 wave, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio wave, and microwave are included within the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead cover non-transitory, 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 disks typically reproduce data magnetically while discs reproduce data optically using a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0378] The 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 circuitry. Accordingly, the term "processor," as used herein, may refer to any of the above structures or any other structure suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Also, the techniques may be implemented entirely in one or more circuits or logic elements.

[0379] The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to highlight functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as noted above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units including one or more processors as described above in conjunction with suitable software and / or firmware. [Explanation of symbols]

[0380] 1 Subpicture 10 Video coding system, coding system 12 Source Device 13 Encoded picture data, communication channel 14 Destination Device 16 Picture Source 17 Picture, Picture Data, Raw Picture, Raw Picture Data, Monochrome Picture, Color Picture, Current Picture 18 Preprocessor, preprocessing unit, picture preprocessor 19 Preprocessed Picture, Preprocessed Picture Data 20 Video Encoder, Encoder 21 Encoded picture data, encoded bitstream 22 Communication interface, communication unit 28 Communication interface, communication unit 30 decoder, video decoder 31 Decoded Picture Data, Decoded Picture 32 Post-processor, post-processing unit 33 Post-processed picture data, post-processed picture 34 Display Devices 46 Processing Circuit 100 Video Encoder 201 Input, input interface 203 Picture Block, Original Block, Current Block, Segmented Block, Current Picture Block 204 Residual Calculation Unit, Residual Calculation 205 Residual Block, Residual 206 Conversion Processing Unit, Conversion 207 Conversion Factor 208 Quantization Unit, Quantization 209 Quantized Coefficients, Quantized Transform Coefficients, Quantized Residual Coefficients 210 Inverse quantization unit, inverse quantization 211 Dequantized Coefficients, Dequantized Residual Coefficients 212 Inverse Transform Processing Unit, (Inverse) Transform 213 Reconstructed residual block, dequantized coefficients, transform block 214 Reconstruction Unit, Adder, Summer 215 reconstructed blocks 216 buffers 220 Loop filter unit, loop filter 221 filtered blocks, filtered reconstructed blocks 230 Decoded Picture Buffer (DPB) 231 decoded pictures 244 Inter Prediction Units 254 Intra prediction unit, Inter prediction unit, Intra prediction 260 Mode Selection Unit 262 Division Unit, Division 265 prediction block, predictor 266 Syntax Elements 270 Entropy Coding Unit, Entropy Coding 272 Output, Output Interface 304 Entropy Decoding Unit, Residual Calculation, Entropy Decoding 309 Quantized Coefficients 310 Inverse Quantization Unit, Inverse Quantization 311 Dequantized Coefficients, Transform Coefficients 312 Inverse Transform Processing Unit, (inverse) transformation, output 313 Reconstructed Residual Blocks 314 Reconstruction Unit, Summer, Adder 315 reconstructed blocks 320 Loop filter, loop filter unit, loop filtering unit 321 filtered blocks, decoded video blocks 330 Decoded Picture Buffer (DPB), Decoded Picture Buffer (DBP) 331 decoded pictures 344 Inter Prediction Unit 354 Intra prediction unit, Intra prediction 360 mode application unit 362 Division 365 predicted blocks 400 Video Coding Device 410 Incoming port, input port 420 Receiver Unit (Rx) 430 Processor, Logic Unit, Central Processing Unit (CPU) 440 Transmitter Unit (Tx) 450 outgoing and outgoing ports 460 memory 470 Coding Module 500 devices 502 processor 504 memory 506 Data 508 Operating Systems 510 Application Program 512 Bus 514 Secondary Storage 518 Display 1600 Video Decoder 1610 Acquisition Units 1620 Judgment Unit 1700 Video Encoder 1710 Judgment Unit 1720 coding units 3100 Contents Supply System 3102 Capture Device 3104 Communication Links 3106 Terminal Device 3108 Smartphones, smart pads 3110 Computers, Laptops 3112 Network Video Recorder (NVR) / Digital Video Recorder (DVR) 3114 TV 3116 Set-top box (STB) 3118 Video Conference System 3120 Video Surveillance System 3122 Personal Digital Assistant (PDA) 3124 In-Vehicle Devices 3126 Display 3202 Protocol Progression Unit 3204 Demultiplexing Unit 3206 Video Decoder 3208 Audio Decoder 3210 Subtitle Decoder 3212 Synchronous Unit 3214 Video / Audio Display 3216 Video / Audio / Subtitle Display

Claims

1. 1. A decoding method comprising: obtaining a first syntax element and a third syntax element from a sequence parameter set (SPS) in a video bitstream, wherein a value of the first syntax element specifies whether a decoded picture buffer (DPB) parameters syntax structure is present in the SPS, the SPS includes syntax elements that apply to a video sequence, and a value of the third syntax element plus one specifies a maximum number of temporal sub-layers that may be present in the video sequence that references the SPS; When the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS, When the value of the third syntax element is greater than 0, obtain a second syntax element from the SPS, or when the second syntax element is not present, infer the value of the second syntax element to be 0, wherein the value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; obtaining the DPB parameter syntax structure from the SPS using the value of the third syntax element as a first input parameter and the value of the second syntax element as a second input parameter; A method comprising:

2. The value of the first syntax element specifies whether a DPB parameter syntax structure is present in the SPS; a value of the first syntax element equal to 1 specifies that the DPB parameter syntax structure is present in the SPS; or A value of the first syntax element equal to 0 specifies that the DPB parameter syntax structure is not present in the SPS.

2. The method of claim 1, comprising:

3. The value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; when the value of the second syntax element is equal to 0, the syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameters syntax structure only for the highest sublayer; or When the value of the second syntax element is equal to 1, for each sublayer, syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameter syntax structure. Including, The value obtained by adding 1 to the max_dec_pic_buffering_minus1 specifies the maximum required size of the decoded picture buffer in units of picture storage buffers, the max_num_reorder_pics specifies the maximum allowable number of pictures in an output layer set (OLS) that can precede any picture in the OLS in decoding order and follow that picture in output order; 3. The method of claim 1 or 2, wherein max_latency_increase_plus1, not equal to 0, is used to calculate a value of MaxLatencyPictures[i], which specifies the maximum number of pictures in the OLS that can precede any picture in the OLS in output order and follow that picture in decoding order.

4. 1. An encoding method comprising: encoding a first syntax element and a third syntax element into a sequence parameter set (SPS) in a video bitstream, wherein a value of the first syntax element specifies whether a decoded picture buffer (DPB) parameters syntax structure is present in the SPS, and a value of the third syntax element plus one specifies a maximum number of temporal sub-layers present in a video sequence that references the SPS; When the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS, When the value of the third syntax element is greater than 0, encoding a second syntax element into the SPS, wherein the value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; encoding the DPB parameter syntax structure into the SPS using the value of the third syntax element as a first input parameter and the value of the second syntax element as a second input parameter; A method comprising:

5. The value of the first syntax element specifies whether a DPB parameter syntax structure is present in the SPS; a value of the first syntax element equal to 1 specifies that the DPB parameter syntax structure is present in the SPS; or A value of the first syntax element equal to 0 specifies that the DPB parameter syntax structure is not present in the SPS.

5. The method of claim 4, comprising:

6. The value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; when the value of the second syntax element is equal to 0, the syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameters syntax structure only for the highest sublayer; or When the value of the second syntax element is equal to 1, for each sublayer, syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameter syntax structure. Including, The value obtained by adding 1 to the max_dec_pic_buffering_minus1 specifies the maximum required size of the decoded picture buffer in units of picture storage buffers, the max_num_reorder_pics specifies the maximum allowable number of pictures in an output layer set (OLS) that can precede any picture in the OLS in decoding order and follow that picture in output order; 6. The method of claim 4 or 5, wherein max_latency_increase_plus1, not equal to 0, is used to calculate the value of MaxLatencyPictures[ i ], which specifies the maximum number of pictures in the OLS that can precede any picture in the OLS in output order and follow that picture in decoding order.

7. An encoder comprising processing circuitry for implementing the method of any one of claims 4 to 6.

8. A decoder comprising processing circuitry for implementing the method of any one of claims 1 to 3.

9. 7. A computer program comprising program code for performing the method of any one of claims 1 to 6 when the computer program is run on a computer or processor.

10. A decoder comprising: one or more processors; a computer-readable storage medium coupled to the processor and storing instructions for execution by the processor, the instructions, when executed by the processor, causing the decoder to perform the method of any one of claims 1 to 3; and Including, a decoder.

11. 1. An encoder comprising: one or more processors; a computer-readable storage medium coupled to the processor and storing instructions for execution by the processor, the instructions, when executed by the processor, causing the encoder to perform the method of any one of claims 4 to 6; and Including, an encoder.

12. A non-transitory computer readable medium having stored thereon program code that, when executed by a computing device, causes the computing device to perform the method of any one of claims 1 to 6.

13. 1. A video bitstream comprising: Contains a sequence parameter set (SPS), the SPS includes a first syntax element and a third syntax element, a value of the first syntax element specifying whether a Decoded Picture Buffer (DPB) parameters syntax structure is present in the SPS, the SPS includes syntax elements that apply to a video sequence, and a value of the third syntax element plus one specifies a maximum number of temporal sub-layers that may be present in the video sequence that references the SPS; When the value of the first syntax element specifies that the DPB parameter syntax structure is present in the SPS, When the value of the third syntax element is greater than 0, the SPS further includes a second syntax element, or when the second syntax element is not present in the SPS, the value of the second syntax element is inferred to be 0, and the value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; the SPS further includes the DPB parameter syntax structure using the value of the third syntax element as a first input parameter and the value of the second syntax element as a second input parameter; Video bitstream.

14. The value of the first syntax element specifies whether a DPB parameter syntax structure is present in the SPS; a value of the first syntax element equal to 1 specifies that the DPB parameter syntax structure is present in the SPS; or A value of the first syntax element equal to 0 specifies that the DPB parameter syntax structure is not present in the SPS.

14. The video bitstream of claim 13, comprising:

15. The value of the second syntax element is used to control the presence of syntax elements in the DPB parameter syntax structure; when the value of the second syntax element is equal to 0, the syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameters syntax structure only for the highest sublayer; or When the value of the second syntax element is equal to 1, for each sublayer, syntax elements max_dec_pic_buffering_minus1, max_num_reorder_pics, and max_latency_increase_plus1 are signaled in the DPB parameter syntax structure. Including, The value obtained by adding 1 to the max_dec_pic_buffering_minus1 specifies the maximum required size of the decoded picture buffer in units of picture storage buffers, the max_num_reorder_pics specifies the maximum allowable number of pictures in an output layer set (OLS) that can precede any picture in the OLS in decoding order and follow that picture in output order; 15. A video bitstream as claimed in claim 13 or 14, wherein max_latency_increase_plus1, not equal to 0, is used to calculate a value of MaxLatencyPictures[ i ], which specifies the maximum number of pictures in the OLS that can precede any picture in the OLS in output order and follow that picture in decoding order.

16. A video bitstream according to any one of claims 13 to 15, or A video bitstream obtained according to the method of any one of claims 4 to 6. A non-transitory storage medium that stores the above.

Images