Encoder, decoder, and corresponding method for chromatic intramode derivation

Abstract

The present invention provides an encoding and decoding apparatus and method that improve the coding efficiency of an intra-predictive mode. [Solution] The decoding method comprises the steps of: acquiring a video bitstream; decoding the video bitstream to acquire an initial intra-prediction mode value for the chroma component of the current coding block; determining whether the ratio between the width for the lumen component of the current coding block and the width for the chroma component of the current coding block is equal to a threshold; and, if it is determined that the ratio is equal to a threshold, acquiring a mapped intra-prediction mode value for the chroma component of the current coding block according to a default mapping relationship and an initial intra-prediction mode value; and acquiring a predicted sample value for the chroma component of the current coding block according to the mapped intra-prediction mode value.

Description

[Technical Field]

[0001] Embodiments of this application (disclosure) relate to the field of picture processing in general, and more specifically to chromatintra predictive mode derivation. [Background technology]

[0002] Video coding (video encoding and video 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 conversational applications like video chat, video conferencing, DVD and Blu-ray® discs, video content collection and editing systems, and camcorders in security applications.

[0003] The amount of video data required to depict even relatively short videos can be considerable, which can pose challenges when data is streamed or transmitted over communication networks with limited bandwidth capacity. Therefore, video data is generally compressed before being transmitted over modern telecommunication networks. Video size can also be an issue when video is stored on storage devices, as memory resources can be limited. Video compression devices often encode video data at the source using software and / or hardware before transmission or storage, thereby reducing the amount of data required to represent the digital video image. The compressed data is then received at the destination by a video decompression device that decodes the video data. Given limited network resources and the increasing demand for higher video quality, improved compression and decompression techniques that improve compression ratios with little to no sacrifice in picture quality are desirable. [Overview of the Initiative] [Means for solving the problem]

[0004] Embodiments of this application provide apparatus and methods for encoding and decoding according to independent claims.

[0005] The above and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are evident from the dependent claims, description, and figures.

[0006] A first aspect of the present invention provides a coding method performed by a decoding device, the method comprising: acquiring a video bitstream; decoding the video bitstream to acquire a value of chroma format display information for the current coding block; acquiring an initial intra-predictive mode value for the chroma component of the current coding block; when the value of chroma format display information for the current coding block is equal to a default value, acquiring a mapped intra-predictive mode value for the chroma component of the current coding block according to a default mapping relationship and an initial intra-predictive mode value; and acquiring a predicted sample value for the chroma component of the current coding block according to the mapped intra-predictive mode value.

[0007] According to embodiments of the present invention, the mapping relationships between intra-prediction modes can be derived more accurately for a chroma subsampling format. Coding efficiency is improved.

[0008] As shown in Figure 13, a coding method performed by a decoding device is disclosed, the method comprising the following:

[0009] S1301: Get the video bitstream.

[0010] Bitstreams can be obtained via wireless or wired networks. Bitstreams can 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, Wi-Fi, Bluetooth, LTE, or 5G.

[0011] In one embodiment, the bitstream is 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 (CVS).

[0012] In some embodiments, during the decoding process, the decoder reads the bitstream and derives the decoded picture from the bitstream, and during the encoding process, the encoder creates the bitstream.

[0013] Typically, a bitstream consists of syntactic elements formed by a syntactic structure.

[0014] Syntax elements: Elements of data represented within a bitstream.

[0015] Syntax structure: Zero or more syntax elements that exist together in a bitstream in a specified order.

[0016] In certain cases, the bitstream format specifies the relationship between network abstraction layer (NAL) unit streams and byte streams, both of which are referred to as bitstreams.

[0017] The bitstream can be in one of two formats, namely, the NAL unit stream format or the byte stream format. The NAL unit stream format is conceptually the more "basic" type. The NAL unit stream format consists of a sequence of syntax structures called NAL units. This sequence is ordered in decode order. There are constraints imposed on the decode order (and content) of the NAL units within the NAL unit stream.

[0018] To form a byte stream, the byte stream format can be constructed from the NAL unit stream format by ordering the NAL units in decode order and prefixing each NAL unit with a start code prefix and zero or more zero-valued bytes. The NAL unit stream format can be extracted from the byte stream format by searching for the position of the unique start code prefix pattern within this byte stream.

[0019] This section specifies the relationship between the source and decoded pictures given via the bitstream.

[0020] The video source represented by the bitstream is a sequence of pictures in decode order.

[0021] The source and decoded pictures each have one or more sample arrays. - Only luma (Y) (monochrome). - Luma and two chroma (YCbCr or YCgCo). - Green, blue, and red (also known as GBR, RGB). - Arrays representing other unspecified monochrome or tristimulus color sampling (e.g., also known as YZX, XYZ).

[0022] The variables and terms associated with these arrays are called chroma (or L or Y) and chroma, where the two chroma arrays are referred to as Cb and Cr, regardless of the actual color representation method used. The actual color representation method used can be indicated in the syntax specified in the VUI parameters, as specified in ITU-T H.SEI | ISO / IEC23002-7.

[0023] The variables SubWidthC and SubHeightC are specified in Table 1, depending on the chroma format sampling structure specified through sps_chroma_format_idc and sps_separate_colour_plane_flag.

[0024] [Table 1]

[0025] In monochromatic sampling, there is nominally only one sample array, which is considered a lumen array.

[0026] In 4:2:0 sampling, each of the two chroma arrays has half the height and half the width of the chroma array.

[0027] In 4:2:2 sampling, each of the two chroma arrays has the same height and half the width of the chroma array.

[0028] In 4:4:4 sampling, the following applies depending on the value of sps_separate_colour_plane_flag: - If sps_separate_colour_plane_flag is equal to 0, then each of the two chromatic arrays has the same height and width as the chromatic array. - Otherwise (sps_separate_colour_plane_flag is equal to 1), the three color planes are processed separately as monochrome sampled pictures.

[0029] S1302: Obtain the initial intra-prediction mode value for the chroma component of the current coding block.

[0030] The initial intra-predictive mode value can be obtained by parsing an index value coded within the video bitstream, or the initial intra-predictive mode value can be determined according to a syntax value parsed from the video bitstream.

[0031] In one implementation, the initial intra-prediction mode value for the chroma component of the current coding block is obtained based on the intra-prediction mode for the lumen component of the current coding block.

[0032] In a specific example, the following process is used to obtain the initial intra-predictive mode value for the chroma component of the current coding block.

[0033] The inputs to this process are as follows: - The rumor position (xCb, yCb) that specifies the top-left sample of the current chromacoding block relative to the top-left rumor sample of the current picture. - A variable cbWidth that specifies the width of the current coding block in the Luma sample. - A variable cbHeight that specifies the height of the current coding block in the ruma sample. - The `treeType` variable specifies whether a single tree or a dual tree is used.

[0034] This process derives the chromin intraprediction mode IntraPredModeC[xCb][yCb] and the MIP chroma direct mode flag MipChromaDirectFlag[xCb][yCb].

[0035] If treeType is equal to SINGLE_TREE, sps_chroma_format_idc is equal to 3, intra_chroma_pred_mode is equal to 4, and intra_mip_flag[ xCb ][ yCb ] is equal to 1, then the following applies: - The MIP chroma direct mode flags MipChromaDirectFlag[xCb][yCb] are set to equal 1. - The Chroma Intra Prediction Mode IntraPredModeC[xCb][yCb] is set to be equal to IntraPredModeY[xCb][yCb].

[0036] Otherwise, the following applies: - The MIP chroma direct mode flags, MipChromaDirectFlag[xCb][yCb], are set to equal to 0. - The corresponding lumaIntraPredMode is derived as follows: - If intra_mip_flag[ xCb + cbWidth / 2 ][ yCb + cbHeight / 2 ] is equal to 1, then lumaIntraPredMode is set to INTRA_PLANAR. - Otherwise, if CuPredMode

[0000] [xCb + cbWidth / 2][yCb + cbHeight / 2] is equal to MODE_IBC or MODE_PLT, lumaIntraPredMode is set to equal to INTRA_DC. - Otherwise, lumaIntraPredMode will be set to IntraPredModeY[ xCb + cbWidth / 2 ][ yCb + cbHeight / 2 ]. - The chromatin intraprediction mode IntraPredModeC[xCb][yCb] is derived as follows: - If cu_act_enabled_flag[ xCb ][ yCb ] is equal to 1, then the chromatin intraprediction mode IntraPredModeC[ xCb ][ yCb ] is set to equal to lumaIntraPredMode. - Otherwise, if BdpcmFlag[ xCb ][ yCb ]

[0001] is equal to 1, then IntraPredModeC[ xCb ][ yCb ] is set to equal to BdpcmDir[ xCb ][ yCb ]

[0001] ? INTRA_ANGULAR50 : INTRA_ANGULAR18. - Otherwise (cu_act_enabled_flag[ xCb ][ yCb ] is equal to 0 and BdpcmFlag[ xCb ][ yCb ]

[0001] is equal to 0), the chroma intrapredation mode IntraPredModeC[ xCb ][ yCb ] is derived using cclm_mode_flag, cclm_mode_idx, intra_chroma_pred_mode, and lumaIntraPredMode as specified in Table 20.

[0037] [Table 2]

[0038] S1303: Decode the video bitstream to obtain the value of the chroma format display information for the current coding block.

[0039] In one embodiment, the chroma format display information is the syntax sps_chroma_format_idc shown in Table 1. sps_chroma_format_idc specifies chroma sampling relative to chroma sampling.

[0040] For example, the syntax sps_chroma_format_idc is decoded from the following sequence parameter set.

[0041] [Table 3]

[0042] There is no particular order to steps S1302 and S1303, and it can be understood that step S1302 may be performed before step S1303, or step S1303 may be performed before step S1302, or they may be performed in parallel.

[0043] S1304: When the value of the chroma format display information for the current coding block is equal to the default value, the mapped intra-prediction mode value for the chroma component of the current coding block is obtained according to the default mapping relationship and initial intra-prediction mode value.

[0044] In one embodiment, the default value is 2 or 1. A default value of 2 indicates a chroma format of 4:2:2, and a default value of 1 indicates a chroma format of 4:2:0.

[0045] In one example, when sps_chroma_format_idc is equal to 2, the chromatintra prediction mode Y is derived using the chromatintra prediction mode X, and then the chromatintra prediction mode X is set to be equal to the chromatintra prediction mode Y.

[0046] The mapping relationship between mode X and mode Y can be represented according to Table 2, Table 3, Table 4, Table 5, Table 6, Table 8, Table 10, Table 12, Table 14, Table 15, or Table 18.

[0047] In one example, when sps_chroma_format_idc is equal to 2, the chromatintra prediction mode Y is derived using the chromatintra prediction mode X in Table 20, as specified in Table 21, and then the chromatintra prediction mode X is set to be equal to the chromatintra prediction mode Y.

[0048] [Table 4]

[0049] S1305: Obtain predicted sample values ​​for the chroma component of the current coding block according to the mapped intra-prediction mode values.

[0050] The mapped intra-prediction mode values ​​are used as “intra-prediction mode values” to obtain prediction sample values. Details of this process can be found in ITU H.264 or ITU H.265 or other documents.

[0051] As shown in Figure 14, a second aspect of the present invention provides a decoding device 1400, the decoding device is A receiving module 1401 configured to acquire a video bitstream, A parameter processing module 1402 is configured to decode a video bitstream and obtain an initial intra-predicted mode value for the chroma component of the current coding block. The parameter processing module 1402 is also configured to decode the video bitstream and obtain values ​​for chroma format display information for the current coding block. When the value of the chroma format display information for the current coding block is equal to the default value, the mapping module 1403 is configured to obtain the mapped intra-predictive mode value for the chroma component of the current coding block according to the default mapping relationship and initial intra-predictive mode value. The system includes a prediction module 1404 configured to obtain predicted sample values ​​for the chroma component of the current coding block according to mapped intra-prediction mode values.

[0052] The method according to the first aspect of the invention can be carried out by the apparatus according to the second aspect of the invention. Further features and implementations of the above method correspond to the features and implementations of the apparatus according to the second aspect of the invention.

[0053] In one embodiment, a third aspect of the present invention provides a coding method performed by an encoding device, comprising the steps of: obtaining an initial intra-predictive mode value for a current coding block; determining whether the ratio between the width of the lumen component of the current coding block and the width of the chroma component of the current coding block is equal to a threshold; if the ratio between the width of the lumen component of the current coding block and the width of the chroma component of the current coding block is equal to a threshold, obtaining a mapped intra-predictive mode value for the chroma component of the current coding block according to a default mapping relationship and an initial intra-predictive mode value; and coding the current coding block according to the mapped intra-predictive mode value.

[0054] In one implementation, the method is: The process further comprises a step of encoding a value of chroma format display information for the current coding block into a bitstream, where the value of chroma format display information represents the ratio between the width of the rumor component of the current coding block and the width of the chroma component of the current coding block.

[0055] In one implementation, the following table is used to represent the default mapping relationships, i.e.,

[0056] [Table 5]

[0057] or

[0058] [Table 6]

[0059] Mode X is used, where Mode Y represents the initial intra-predicted mode value, and Mode Y represents the mapped intra-predicted mode value.

[0060] In one implementation, the following table is used to represent the default mapping relationships, i.e.,

[0061] [Table 7]

[0062] Mode X is used, where Mode Y represents the initial intra-predicted mode value, and Mode Y represents the mapped intra-predicted mode value.

[0063] Further embodiments of the method according to the third aspect of the invention (encoding side) can be performed in correspondence with the method according to the second aspect of the invention (decoding side).

[0064] In one embodiment, a decoder (30) or encoder (20) is disclosed that includes a processing circuit for performing a method according to any one of the embodiments and implementations described above.

[0065] In one embodiment, a computer program product is disclosed that includes program code for performing a method according to any one of the embodiments and implementations described above.

[0066] In one embodiment, a decoder or encoder, One or more processors, A non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the program, when executed by the processor, configures a decoder or encoder to perform a method according to any one of the above embodiments and implementations. A decoder or encoder is disclosed.

[0067] In one embodiment, a non-temporary storage medium is disclosed, which includes an encoded bitstream decoded by an image decoding device, wherein the bitstream is generated by dividing a frame of a video signal or image signal into a plurality of blocks and includes a plurality of syntax elements, the plurality of syntax elements comprising an indicator (syntax sps_chroma_format_idc) according to any one of the above embodiments and implementations.

[0068] Details of one or more embodiments are described in the accompanying drawings and the following description. Other features, purposes, and advantages will become apparent from the description, drawings, and claims.

[0069] Embodiments of the invention will be described in more detail below with reference to the accompanying figures and drawings. [Brief explanation of the drawing]

[0070] [Figure 1A] This is a block diagram representing an example of a video coding system configured to realize an embodiment of the invention. [Figure 1B] This is a block diagram representing another example of a video coding system configured to realize an embodiment of the invention. [Figure 2] This is a block diagram showing an example of a video encoder configured to realize an embodiment of the invention. [Figure 3] This is a block diagram illustrating the structure of an exemplary video decoder configured to realize an embodiment of the invention. [Figure 4] This is a block diagram illustrating an example of an encoding or decoding device. [Figure 5] This is a block diagram illustrating another example of an encoding or decoding device. [Figure 6] This is an example of the chroma subsampling format 4:4:4. [Figure 7] This is an example of the chroma subsampling format 4:2:0. [Figure 8] This is an example of the chroma subsampling format 4:2:2. [Figure 9] This block diagram illustrates an example of a prediction mode. [Figure 10] This shows the original mode and an example of the corresponding mode when chroma subsampling is applied horizontally using the 4:2:2 chroma subsampling format. [Figure 11] This is a block diagram illustrating the structure of an example content supply system 3100 that implements a content distribution service. [Figure 12] This is a block diagram showing the structure of an example terminal device. [Figure 13] This is a flowchart illustrating an embodiment of the method referred to in the present invention. [Figure 14] This is a block diagram showing an embodiment of the apparatus referred to in the present invention. [Modes for carrying out the invention]

[0071] In the following, the same reference numeral refers to the same or at least functionally equivalent feature unless explicitly specified elsewhere.

[0072] The following description includes references to the accompanying drawings, which form part of the disclosure and illustrate specific embodiments of the invention or specific ways in which embodiments of the invention may be used. It is understood that embodiments of the invention may be used in other embodiments and may have structural or logical modifications not depicted in the drawings. Accordingly, the following detailed description should not be taken as limiting, and the scope of the invention is defined by the accompanying claims.

[0073] For example, it is understood that disclosures regarding a described method may also apply to corresponding devices or systems configured to perform that method, and vice versa. For example, if one or more specific steps of a method are described, the corresponding device may include one or more units for performing the steps of the described method, e.g., functional units (e.g., one unit performing one or more steps, or multiple units, each performing one or more of the steps). On the other hand, if a particular device is described based on one or more units, e.g., functional units, the corresponding method may include one step for performing the function of one or more units (e.g., one step performing the function of one or more units, or multiple steps, each performing one or more of the functions of multiple units), e.g., if one or more such steps are not explicitly described or e.g.,

[0074] Video coding typically refers to the processing of a sequence of pictures that form a video or 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 coding in general) comprises two parts: video encoding and video decoding. Video encoding is performed on the source side and typically involves processing the original video picture (e.g., by compression) to reduce the amount of data required to represent the video picture (for more efficient storage and / or transmission). Video decoding is performed on the destination side and typically involves the reverse processing compared to encoding, for the purpose of reconstructing the video picture. Embodiments referring to "coding" of a video picture (or picture in general) shall be understood to relate to "encoding" or "decoding" of the video picture or each video sequence. The combination of the encoding and decoding parts is also called a CODEC (Coding and Decoding).

[0075] In lossless video coding, the original video picture can be reconstructed, meaning that (assuming there is no transmission loss or other data loss during storage or transmission) the reconstructed video picture will have the same quality as the original video picture. In lossy video coding, further compression is performed, for example by quantization, to reduce the amount of data representing the video picture, and the video picture cannot be fully reconstructed in the decoder, meaning the quality of the reconstructed video picture is lower or worse than the quality of the original video picture.

[0076] Some video coding standards belong to the group of "lossy hybrid video codecs" (i.e., combining spatial and temporal prediction in the sample domain with 2D transform coding to apply quantization in the transform domain). Each picture in a video sequence is typically divided into a set of non-overlapping blocks, and coding is typically performed at the block level. In other words, in the encoder, video is typically processed, i.e., encoded, at the block (video block) level by generating predicted blocks using, for example, spatial (intra-picture) prediction and / or temporal (inter-picture) prediction, subtracting the predicted blocks from the current block (the block currently being processed / 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). In the decoder, on the other hand, the reverse process compared to the encoder is applied to the encoded or compressed block to reconstruct the current block for representation. Furthermore, the encoder duplicates the decoder processing loop so that both produce identical predictions (e.g., intra and inter predictions) and / or reconstructions for processing, i.e., coding, the subsequent blocks.

[0077] Hereinafter, embodiments of the video coding system 10, video encoder 20, and video decoder 30 will be described with reference to Figures 1 to 3.

[0078] Figure 1A is a schematic block diagram illustrating an exemplary coding system 10 that may utilize the techniques of this application, for example, a video coding system 10 (or coding system 10 for short). The video encoder 20 (or encoder 20 for short) and video decoder 30 (or decoder 30 for short) of the video coding system 10 represent an example of a device that may be configured to perform the techniques described in the various examples in this application.

[0079] As shown in Figure 1A, the coding system 10 includes a source device 12 configured to provide encoded picture data 21 to a destination device 14 for decoding encoded picture data 13.

[0080] The source device 12 includes an encoder 20 and, optionally, a picture source 16, a preprocessor (or preprocessing unit) 18, for example, a picture preprocessor 18, and a communication interface or communication unit 22.

[0081] The picture source 16 comprises, or may comprise, 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 other kind of device for acquiring 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). The picture source may be any kind of memory or storage device for storing any of the pictures described above.

[0082] To distinguish it from the processing performed by the preprocessor 18 and the preprocessing unit 18, the picture or picture data 17 may also be called the raw picture or raw picture data 17.

[0083] The preprocessor 18 is configured to receive (unprocessed) picture data 17, perform preprocessing on the picture data 17, and obtain a preprocessed picture 19 or preprocessed picture data 19. The preprocessing performed by the preprocessor 18 may include, for example, cropping, color format conversion (e.g., from RGB to YCbCr), color correction, or noise reduction. It can be understood that the preprocessing unit 18 may be an optional component.

[0084] The video encoder 20 is configured to receive pre-processed picture data 19 and provide encoded picture data 21 (further details will be described below, for example, based on Figure 2).

[0085] 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) over the communication channel 13 to another device, such as the destination device 14 or any other device, for storage or direct reconstruction.

[0086] The destination device 14 includes a decoder 30 (e.g., a video decoder 30), and may also include, optionally, a communication interface or communication unit 28, a post-processor 32 (or post-processing unit 32), and a display device 34.

[0087] The communication interface 28 of the destination device 14 is configured to receive encoded picture data 21 (or any further processed version thereof) from, for example, directly from the source device 12 or from any other source, for example, a storage device, for example, an encoded picture data storage device, and to provide the encoded picture data 21 to the decoder 30.

[0088] Communication interfaces 22 and 28 may be configured to transmit or receive encoded picture data 21 or encoded data 13 via a direct communication link between the source device 12 and the destination device 14, for example, via a direct wired or wireless connection, or via any type of network, for example, a wired or wireless network or any combination thereof, or any type of private and public network or any combination thereof.

[0089] The communication interface 22 may be configured to package the encoded picture data 21 in an appropriate format, for example, in a packet, and / or to process the encoded picture data using any kind of transmission encoding or processing for transmission over a communication link or communication network.

[0090] The communication interface 28, which forms the other end of the communication interface 22, may be configured, for example, to receive transmitted data and process the transmitted data using any kind of corresponding transmission decoding or processing and / or package removal to obtain encoded picture data 21.

[0091] Both communication interfaces 22 and 28 may be configured as unidirectional or bidirectional communication interfaces, as indicated by the arrows for communication channel 13 in Figure 1A, pointing from source device 12 to destination device 14, and may be configured to send and receive messages, for example, to set up a connection, to acknowledge and exchange any other information, such as communication links and / or data transmission, such as encoded picture data transmission.

[0092] The decoder 30 is configured to receive encoded picture data 21 and provide decoded picture data 31 or decoded picture 31 (further details will be described below, for example, based on Figure 3 or Figure 5).

[0093] The post-processor 32 of the destination device 14 is configured to post-process the decoded picture data 31 (also called reconstructed picture data), for example, the decoded picture 31, to obtain post-processed picture data 33, for example, the post-processed picture 33. The post-processing performed by the post-processing unit 32 may include, for example, color format conversion (e.g., from YCbCr to RGB), color correction, cropping, or resampling, or any other processing, to prepare the decoded picture data 31 for display by the display device 34, for example.

[0094] The display device 34 of the destination device 14 is configured to receive, for example, post-processed picture data 33 for displaying the picture to a user or viewer. The display device 34 may be, or comprise, any type of display for representing the reconstructed picture, such as an integrated or external display or monitor. The display may comprise, 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.

[0095] Figure 1A depicts the source device 12 and the destination device 14 as separate devices, but the device embodiment may also comprise both or both of the functions of the source device 12 or its corresponding function and the destination device 14 or its corresponding function. In such embodiments, the source device 12 or its corresponding function and the destination device 14 or its corresponding function may be implemented using the same hardware and / or software, or by separate hardware and / or software, or any combination thereof.

[0096] As will become apparent to those skilled in the art based on the description, the functions of different units or the presence and (exact) division of functions within source device 12 and / or destination device 14 as shown in Figure 1A may vary depending on the actual device and application.

[0097] An encoder 20 (e.g., a video encoder 20) or a decoder 30 (e.g., a video decoder 30), or both an encoder 20 and a decoder 30, may be implemented via processing circuits, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, dedicated video coding, or any combination thereof, as shown in Figure 1B. The encoder 20 may be implemented via processing circuits 46 to embody various modules, such as those discussed with respect to the encoder 20 in Figure 2, and / or any other encoder systems or subsystems described herein. The decoder 30 may be implemented via processing circuits 46 to embody various modules, such as those discussed with respect to the decoder 30 in Figure 3, and / or any other decoder systems or subsystems described herein. The processing circuits may be configured to perform various operations, as will be discussed later. If the technique is partially implemented in software, as shown in Figure 5, the device may store instructions for the software in a suitable non-temporary computer-readable storage medium, and may use one or more processors to execute the instructions in hardware to perform the technique of this disclosure. Either the video encoder 20 or the video decoder 30 may be integrated within a single device as part of a combined encoder / decoder (CODEC), for example, as shown in Figure 1B.

[0098] The source device 12 and destination device 14 may comprise any of a wide range of devices, including any type of handheld or stationary device, such as a notebook or laptop computer, mobile phone, smartphone, tablet or tablet computer, camera, desktop computer, set-top box, television, display device, digital media player, video game console, video streaming device (such as a content service server or content distribution server), broadcast receiver device, broadcast transmitter device, or similar, and may or may not have an operating system. In some cases, the source device 12 and destination device 14 may be equipped for wireless communication. Thus, the source device 12 and destination device 14 may be wireless communication devices.

[0099] In some cases, the video coding system 10 illustrated in Figure 1A is merely an example, and the techniques of this application may be applied to video coding settings (e.g., video encoding or video decoding) without necessarily involving any data communication between encoding and decoding devices. In other examples, data may be retrieved from local memory, streamed over a network, or similar. 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 into memory and / or retrieve data from memory and decode it.

[0100] For the sake of explanation, embodiments of the invention are described herein by reference to, for example, High-Efficiency Video Coding (HEVC) or to reference software for Versatile Video Coding (VVC), a next-generation video coding standard developed by the Joint Collaboration Team on Video Coding (JCT-VC) of the ITU-T Video Coding Experts Group (VCEG) and the ISO / IEC Motion Picture Experts Group (MPEG). Those skilled in the art will understand that embodiments of the invention are not limited to HEVC or VVC.

[0101] Encoder and encoding method Figure 2 shows a schematic block diagram of an exemplary video encoder 20 configured to implement the technique of the present application. In the example of Figure 2, the video encoder 20 comprises an input 201 (or input interface 201), a residual calculation unit 204, a transformation unit 206, a quantization unit 208, an inverse quantization unit 210, and an inverse transformation unit 212, a reconstruction unit 214, a loop filter unit 220, a decoded picture buffer (DPB) 230, a mode selection unit 260, an entropy encoding 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 segmentation unit 262. The inter-prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The video encoder 20 as shown in Figure 2 may also be called a hybrid video encoder or a video encoder with a hybrid video codec.

[0102] The residual calculation unit 204, the conversion processing unit 206, the quantization unit 208, and the mode selection unit 260 may be referred to as forming the forward signal path of the encoder 20, while the inverse quantization unit 210, the inverse conversion processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, the inter-prediction unit 244, and the intra-prediction unit 254 may be referred to as forming the reverse signal path of the video encoder 20, where the reverse signal path of the video encoder 20 corresponds to the signal path of the decoder (see video decoder 30 in Figure 3). The inverse quantization unit 210, the inverse conversion processing unit 212, the reconstruction unit 214, the loop filter 220, the decoded picture buffer (DPB) 230, the inter-prediction unit 244, and the intra-prediction unit 254 may also be referred to as forming the “built-in decoder” of the video encoder 20.

[0103] Pictures and picture sections (pictures and blocks) The encoder 20 may be configured to receive, for example, a picture 17 (or picture data 17), for example, a picture of a sequence of pictures forming a video or video sequence, via input 201. The received picture or picture data may also be a pre-processed picture 19 (or pre-processed picture data 19). For the sake of brevity, the following description will refer to picture 17. Picture 17 may also be called the current picture, or the picture to be coded (particularly in video coding, to distinguish the current picture from other pictures in the same video sequence, i.e., other video sequences that also have the current picture, e.g., pictures that have been previously encoded and / or decoded).

[0104] A (digital) picture is, or can be considered as, a two-dimensional array or matrix of samples having intensity values. A sample in an array may also be called a pixel (a short form of picture element) or pel. 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, typically three color components are employed; i.e., a picture may represent or contain three sample arrays. In the RGB format or color space, a picture has corresponding red, green, and blue sample arrays. However, in video coding, each pixel is typically represented in a luminance and chrominance format or color space, e.g., YCbCr, where YCbCr comprises a luminance component represented by Y (sometimes L is also used instead) and two chrominance components represented by Cb and Cr. The luminance (or abbreviated as luma) component Y represents brightness or gray level intensity (for example, in a grayscale picture), while the two chrominance (or abbreviated as chroma) components Cb and Cr represent chromaticity or color information components. Thus, a picture in YCbCr format comprises 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 to or from YCbCr format, and vice versa; the process is also known as color conversion or conversion. If the picture is monochrome, the picture may comprise 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.

[0105] Embodiments of the video encoder 20 may include a picture partitioning unit (not shown in Figure 2) configured to divide a picture 17 into a plurality of (typically 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 use the same block size and corresponding grid defining the block size for all pictures in the video sequence, or it may change the block size between pictures or subsets or groups of pictures to partition each picture into a corresponding block.

[0106] In a further embodiment, the video encoder may be configured to directly receive blocks 203 of picture 17, for example, one, some, or all of the blocks that make up picture 17. Picture block 203 may also be called the current picture block or the picture block to be coded.

[0107] Like picture 17, picture block 203 is again a two-dimensional array or matrix of samples having intensity values ​​(sample values), but smaller in dimensions than picture 17, or can be considered as such. In other words, block 203 may comprise, for example, one sample array (e.g., a lumen array in the case of monochrome picture 17, or a lumen or chromen array in the case of a color picture), or three sample arrays (e.g., a lumen and two chromen arrays in the case of color picture 17), or any other number and / or type of arrays 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, the block may be, for example, an M×N (M columns × N rows) array of samples, or an M×N array of conversion coefficients.

[0108] An embodiment of the video encoder 20, as shown in Figure 2, may be configured to encode the picture 17 block by block, for example, encoding and prediction may be performed for each block 203.

[0109] An embodiment of the video encoder 20, as shown in Figure 2, may be further configured to divide and / or encode a picture by using slices (also called video slices), the picture may be divided into one or more slices (typically non-overlapping) or encoded using those slices, each slice may comprise one or more blocks (e.g., CTUs).

[0110] Embodiments of the video encoder 20, as shown in Figure 2, may be further configured to divide and / or encode a picture by using tile groups (also called video tile groups) and / or tiles (also called video tiles), wherein the picture may be divided into one or more (typically non-overlapping) tile groups or encoded using such tile groups, each tile group may comprise, for example, one or more blocks (e.g., CTUs) or one or more tiles, each tile may be, for example, rectangular in shape and comprise one or more blocks (e.g., CTUs), for example, complete or fragmented blocks.

[0111] Residual calculation The residual calculation unit 204 may be configured to obtain the residual block 205 (also called residual 205) based on picture block 203 and prediction block 265 (further details about prediction block 265 will be provided later) by subtracting the sample value of prediction block 265 from the sample value of picture block 203 for each sample (for each pixel), for example, to obtain the residual block 205 in the sample region.

[0112] conversion The transformation processing unit 206 may be configured to obtain transformation coefficients 207 in the transformation domain by applying a transformation, for example, a discrete cosine transform (DCT) or a discrete sine transform (DST), to the sample values ​​of the residual block 205. The transformation coefficients 207, also called transformation residual coefficients, may represent the residual block 205 in the transformation domain.

[0113] The conversion processing unit 206 may be configured to apply an integer approximation of the DCT / DST, such as the specified conversion for H.265 / HEVC. Compared to the orthogonal DCT conversion, such an integer approximation is typically scaled by a certain coefficient. An additional scaling coefficient is applied as part of the conversion process to maintain the norm of the residual blocks processed by the forward and inverse conversions. The scaling coefficient is typically chosen based on certain constraints, such as the scaling coefficient being a power of 2 for the shift operation, the bit depth of the conversion coefficient, and a trade-off between accuracy and implementation cost. For example, a specific scaling coefficient may be specified for the inverse conversion (and the corresponding inverse conversion by the inverse conversion processing unit 312 in the video decoder 30, for example) by the inverse conversion processing unit 212, and a corresponding scaling coefficient for the forward conversion in the encoder 20, for example by the conversion processing unit 206, may be specified accordingly.

[0114] Embodiments of the video encoder 20 (each a conversion processing unit 206) may be configured to output conversion parameters, for example, one or more types of conversion, which are encoded or compressed, for example, directly or via the entropy encoding unit 270, so that, for example, the video decoder 30 can receive and use the conversion parameters for decoding.

[0115] Quantization The quantization unit 208 may be configured to quantize the transformation coefficients 207 to obtain quantized coefficients 209, for example, by applying scalar quantization or vector quantization. The quantized coefficients 209 may also be called quantized transformation coefficients 209 or quantized residual coefficients 209.

[0116] The quantization process can reduce the bit depth associated with some or all of the 207 conversion coefficients. For example, n-bit conversion coefficients may be truncated to m-bit conversion coefficients during quantization, where n is greater than m. The degree of quantization can be modified by adjusting the Quantization Parameter (QP). For example, for scalar quantization, different scalings may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, while larger quantization step sizes correspond to coarser quantization. Applicable quantization step sizes can be indicated by the Quantization Parameter (QP). The quantization parameter may be, for example, an index to a default set of applicable quantization step sizes. For example, a small quantization parameter may correspond to finer quantization (smaller quantization step size), a large quantization parameter may correspond to coarser quantization (larger quantization step size), and vice versa. Quantization may involve division by the quantization step size, and the corresponding and / or inverse dequantization by the inverse quantization unit 210 may involve multiplication by the quantization step size. Some standards, e.g., the HEVC embodiment, may be configured to determine the quantization step size using quantization parameters. Generally, the quantization step size may be calculated based on the quantization parameters using a fixed-point approximation of the equations 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 the scaling used in the fixed-point approximation of the equations for the quantization step size and quantization parameters. In one exemplary implementation, the scaling of the inverse transform and dequantization may be combined. Alternatively, a customized quantization table may be used and signaled from encoder to decoder, for example, within a bitstream. Quantization is a lossy operation, and the loss increases with increasing quantization step size.

[0117] Embodiments of the video encoder 20 (each a quantization unit 208) may be configured to output quantization parameters (QP) that are encoded, for example, directly or via an entropy encoding unit 270, so that, for example, a video decoder 30 can receive and apply the quantization parameters for decoding.

[0118] inverse quantization The inverse quantization unit 210 is configured to obtain dequantized coefficients 211 by applying the inverse of the quantization scheme applied by the quantization unit 208 to the quantized coefficients, for example, based on or using the same quantization step size as the quantization unit 208. The dequantized coefficients 211, also called dequantized residual coefficients 211, are typically not identical to the transformation coefficients due to quantization losses, but may correspond to the transformation coefficients 207.

[0119] Inverse Transform The inverse transform processing unit 212 is configured to apply the inverse transform of the transform applied by the transform processing unit 206, for example, the inverse discrete cosine transform (DCT) or the inverse discrete sine transform (DST), or any other inverse transform, to obtain a reconstructed residual block 213 (or the corresponding dequantized coefficient 213) in the sample region. The reconstructed residual block 213 may also be called the transform block 213.

[0120] Reconstruction The reconstruction unit 214 (e.g., an adder or summer 214) is configured to obtain the reconstructed block 215 in the sample region by adding the sample values ​​of the reconstructed residual block 213 and the sample values ​​of the prediction block 265 sample by sample, thereby adding the transformed block 213 (i.e., the reconstructed residual block 213) to the prediction block 265.

[0121] Filtering The loop filter unit 220 (or, for short, the "loop filter" 220) is configured to filter the reconstructed block 215 to obtain a filtered block 221, or generally to filter the reconstructed sample to obtain a filtered sample. The loop filter unit is configured, for example, to smooth pixel transitions or otherwise improve video quality. The loop filter unit 220 may comprise 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, smoothing filter, or a co-filter, or any combination thereof. Although the loop filter unit 220 is shown in Figure 2 as 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 called a filtered reconstructed block 221.

[0122] Embodiments of the video encoder 20 (each a loop filter unit 220) may be configured to output loop filter parameters (such as sample-adaptive offset information), either directly or encoded via the entropy encoding unit 270, so that, for example, the decoder 30 can receive and apply the same loop filter parameters or the respective loop filters for decoding.

[0123] Decoded picture buffer The decoded picture buffer (DPB) 230 may be a memory that stores a reference picture or generally reference picture data for encoding video data by the video encoder 20. The DPB 230 may be formed by 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 be further configured to store other previously filtered blocks, e.g., previously reconstructed and filtered blocks 221 of the same current picture or different pictures, e.g., previously reconstructed pictures, for example, for interpretation, it may provide a previously reconstructed, i.e., decoded complete picture (and corresponding reference blocks and samples) and / or a partially reconstructed current picture (and corresponding reference blocks and samples). For example, if a reconstructed block 215 is not filtered by the loop filter unit 220, or any other further processed version of a reconstructed block or sample, the decoded picture buffer (DPB) 230 may also be configured to store one or more unfiltered reconstructed blocks 215, or generally, unfiltered reconstructed samples.

[0124] Mode selection (category and prediction) The mode selection unit 260 comprises a segmentation unit 262, an inter-prediction unit 244, and an intra-prediction unit 254, and is configured to receive or acquire reconstructed picture data, such as filtered and / or unfiltered reconstructed samples or blocks, from the original picture data, such as the original block 203 (the current block 203 of the current picture 17), and from the same (current) picture and / or from one or more previously decoded pictures, such as the decoded picture buffer 230 or other buffers (e.g., an unrepresented line buffer). The reconstructed picture data is used as reference picture data for predictions, such as inter-prediction or intra-prediction, in order to acquire prediction blocks 265 or predictors 265.

[0125] The mode selection unit 260 may be configured to determine or select a division and a prediction mode (e.g., intra or inter prediction mode) for the current block prediction mode (excluding divisions), and to generate a corresponding prediction block 265 to be used for calculating the residual block 205 and for reconstructing the reconstructed block 215.

[0126] Embodiments of the mode selection unit 260 may be configured to select a partition and predictive mode (for example, from those supported by or available to the mode selection unit 260) that provides the best fit, or in other words, minimum residual (minimum residual means better compression for transmission or storage), or minimum signaling overhead (minimum signaling overhead means better compression for transmission or storage), or takes both into consideration or balances them. The mode selection unit 260 may be configured to determine the partition and predictive modes based on Rate Distortion Optimization (RDO), i.e., to select a predictive mode that provides the minimum rate distortion. In this context, terms such as “best,” “minimum,” and “optimal” do not necessarily refer to an overall “best,” “minimum,” and “optimal,” but may refer to the satisfaction of a termination or selection criterion, such as a value above or below a threshold or other constraint, which may potentially lead to a “suboptimal selection” but reduce complexity and processing time.

[0127] In other words, the partitioning unit 262 may be configured to partition block 203 into smaller block partitions or subblocks (which then form blocks) by iteratively using, for example, quad-tree partitioning (QT), binary partitioning (BT), or triple-tree partitioning (TT), or any combination thereof, and to perform predictions for each of the block partitions or subblocks, wherein mode selection comprises a selection of the tree structure of the block 203 to be partitioned, and prediction modes are applied to each of the block partitions or subblocks.

[0128] The following will describe in more detail the segmentation (by the segmentation unit 260, for example) and prediction (by the inter-prediction unit 244 and the intra-prediction unit 254) processes performed by the example video encoder 20.

[0129] classification The partitioning unit 262 may partition (or divide) the current block 203 into smaller partitions, for example, smaller blocks of square or rectangular size. These smaller blocks (also called subblocks) may be further partitioned into even smaller partitions. This is also called tree partitioning or hierarchical tree partitioning. For example, the root block at root tree level 0 (hierarchy level 0, depth 0) may be recursively partitioned into, for example, two or more blocks at the next lower tree level, for example, a node at tree level 1 (hierarchy level 1, depth 1), and these blocks may again be partitioned into two or more blocks at the next lower level, for example, tree level 2 (hierarchy level 2, depth 2), until a termination criterion is met, for example, the maximum tree depth or minimum block size is reached and the partitioning ends. Blocks that are not further partitioned are also called leaf blocks or leaf nodes of the tree. A tree that uses divisions into two parts is called a binary tree (BT), a tree that uses divisions into three parts is called a ternary tree (TT), and a tree that uses divisions into four parts is called a quad tree (QT).

[0130] As previously stated, the term “block” as used herein may refer to a portion of a picture, particularly a square or rectangular portion. For example, with reference to HEVC and VVC, a block may be, or may 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).

[0131] For example, a coding tree unit (CTU) may be a CTB for a lumen sample of a picture having three sample arrays, two corresponding CTBs for a chroma sample, or a CTB for a sample of a picture coded using a monochrome picture or three separate color planes, and a syntax structure used to code the sample. Correspondingly, a coding tree block (CTB) may be an N×N block of sample for some value of N such that the division of components into the CTB is a partition. A coding unit (CU) may be a coding block for a lumen sample of a picture having three sample arrays, two corresponding coding blocks for a chroma sample, or a coding block for a sample of a picture coded using a monochrome picture or three separate color planes, and a syntax structure used to code the sample. Correspondingly, a coding block (CB) may be an M×N block of sample for some value of M and N such that the division of the CTB into the coding block is a partition.

[0132] For example, in an embodiment using HEVC, a coding tree unit (CTU) can be divided into CUs by using a quadtree structure that is represented as a coding tree. The decision of whether to code a picture area using (temporal) interpicture prediction or (spatial) intrapicture prediction is made at the CU level. Each CU can be further divided into one, two, or four PUs according to the PU partitioning type. Within a single PU, the same prediction process is applied, and the relevant information is transmitted to the decoder for each PU. After obtaining residual blocks by applying the prediction process based on the PU partitioning type, the CU can be divided into transformation units (TUs) according to another quadtree structure similar to a coding tree for the CU.

[0133] For example, in an embodiment of the latest video coding standard currently under development, called Multipurpose Video Coding (VVC), combined quad-tree and binary tree (Quad-Tree and Binary Tree (QTBT)) segmentations are used, for example, to segment coding blocks. In a QTBT block structure, CUs can have either a square or rectangular shape. For example, a coding tree unit (CTU) is initially segmented by a quad-tree structure. The quad-tree leaf nodes are further segmented by a binary or ternary (or triple-tree) structure. The segmenting tree leaf nodes are called coding units (CUs), and their segmentation is used for prediction and transformation processing without further segmentation. This means that CUs, PUs, and TUs have the same block size in a QTBT coding block structure. In parallel, multiple segmentations, such as triple-tree segmentations, may be used in conjunction with the QTBT block structure.

[0134] In one example, the mode selection unit 260 of the video encoder 20 may be configured to perform any combination of the segmentation techniques described herein.

[0135] As described above, the video encoder 20 is configured to determine or select the best or optimal prediction mode from a set of prediction modes (for example, a predetermined set). The set of prediction modes may include, for example, an intra-prediction mode and / or an inter-prediction mode.

[0136] Intra Prediction The set of intra-prediction modes may comprise, for example, 35 different intra-prediction modes, such as DC (or average) mode and planar mode, or directional modes, as defined in HEVC, or 67 different intra-prediction modes, such as DC (or average) mode and planar mode, or directional modes, as defined in VVC.

[0137] The intra-prediction unit 254 is configured to use reconfigured samples of adjacent blocks of the same current picture to generate an intra-prediction block 265 according to the intra-prediction mode of a set of intra-prediction modes.

[0138] The intra-prediction unit 254 (or generally the mode selection unit 260) is further configured to output intra-prediction parameters (or generally information indicating a selected intra-prediction mode for a block) in the form of syntax elements 266 to the entropy encoding unit 270 for inclusion in the encoded picture data 21, thereby allowing, for example, the video decoder 30 to receive and use the prediction parameters for decoding.

[0139] Interpretation The set of interpretation modes (or possible interpretation modes) depends on the available reference picture (i.e., a previously decoded picture, at least partially, stored in DBP 230), and other interpretation parameters, such as whether the entire reference picture is used to search for the best-matching reference block, or only a portion of the reference picture, such as the search window area around the current block's area, and / or whether pixel interpolation, such as half / semi-per and / or quarter-per interpolation, is applied.

[0140] In addition to the prediction modes described above, skip mode and / or direct mode may be applied.

[0141] The interpretation unit 244 may include a motion estimation (ME) unit and a motion compensation (MC) unit (neither of which are shown in Figure 2). The motion estimation unit may be configured to receive or acquire, for motion estimation, a picture block 203 (the current picture block 203 of the current picture 17) and a decoded picture 231, or at least one or more previously reconstructed blocks, e.g., one or more other / different reconstructed blocks of a previously decoded picture 231. For example, a video sequence may comprise the current picture and a previously decoded picture 231, or in other words, the current picture and a previously decoded picture 231 may be part of a sequence of pictures that make up the video sequence, or may make up the sequence.

[0142] The encoder 20 may be configured, for example, to select a reference block from multiple reference blocks of the same or different pictures among several other pictures, and to provide the motion estimation unit with the reference picture (or reference picture index), and / or the offset (spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block as interpretation parameters. This offset is also called the motion vector (MV).

[0143] The motion compensation unit is configured to obtain, for example, interprediction parameters and, based on or using the interprediction parameters, perform interprediction to obtain interprediction block 265. Motion compensation performed by the motion compensation unit may involve fetching or generating prediction blocks based on motion / block vectors determined by motion estimation, possibly performing interpolation to sub-pixel precision. Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that can be used to code picture blocks. Upon receiving motion vectors for the current picture block's PU, the motion compensation unit may position the prediction block pointed to by the motion vectors in one of the reference picture lists.

[0144] The motion compensation unit may also generate syntax elements associated with blocks and video slices for use by the video decoder 30 when decoding picture blocks of 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.

[0145] Entropy coding The entropy encoding unit 270 uses quantized coefficients 209, inter-prediction parameters, intra-prediction parameters, loop filter parameters, and / or other syntax elements, for example, entropy encoding algorithms or schemes (e.g., variable length coding (VLC) scheme, context adaptive VLC scheme (CAVLC)), arithmetic coding scheme, binarization, context adaptive binary arithmetic coding (CABAC)), syntax-based context-adaptive binary arithmetic coding (SBAC)), probability interval partitioning entropy. Entropy (PIPE) coding (or another entropy encoding methodology or technique), or bypass (no compression) is applied to obtain encoded picture data 21 which can be output via output 272 in the form of an encoded bitstream 21, so that, for example, a video decoder 30 can receive and use parameters for decoding. The encoded bitstream 21 can be transmitted to the video decoder 30 or stored in memory for later transmission or retrieval by the video decoder 30.

[0146] Other structural variations of the video encoder 20 can be used to encode a video stream. For example, an unconverted encoder 20 can directly quantize the residual signal for a given block or frame without a conversion processing unit 206. In another implementation, the encoder 20 may have a quantization unit 208 and an inverse quantization unit 210 combined in a single unit.

[0147] Decoder and decoding method Figure 3 shows an example of a video decoder 30 configured to implement the technique of this invention. The video decoder 30 is configured to receive encoded picture data 21 (e.g., encoded bitstream 21) encoded by the encoder 20, for example, and to obtain a decoded picture 331. The encoded picture data or bitstream comprises information for decoding the encoded picture data, for example, data representing picture blocks of an encoded video slice (and / or tile group or tile), and associated syntax elements.

[0148] In the example shown in Figure 3, the decoder 30 comprises an entropy decoding unit 304, an inverse quantization unit 310, an inverse transformation processing unit 312, a reconstruction unit 314 (e.g., an aggregater 314), a loop filter 320, a decoded picture buffer (DBP) 330, a mode application unit 360, an interpretation unit 344, and an intraprediction unit 354. The interpretation unit 344 may be or may include a motion compensation unit. In some examples, the video decoder 30 may perform a decoding path that is generally complementary to the encoding path described with respect to the video encoder 100 from Figure 2.

[0149] As described with respect to encoder 20, the inverse quantization unit 210, inverse 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 referred to as forming the “built-in decoder” of video encoder 20. Thus, the inverse quantization unit 310 may be functionally identical to the inverse quantization unit 110, the inverse processing unit 312 may be functionally identical to the inverse processing unit 212, the reconstruction unit 314 may be functionally identical to the reconstruction unit 214, the loop filter 320 may be functionally identical to the loop filter 220, and the decoded picture buffer 330 may be functionally identical to the decoded picture buffer 230. Accordingly, the descriptions provided for each unit and function of video encoder 20 apply correspondingly to each unit and function of video decoder 30.

[0150] Entropy Decode The entropy decoding unit 304 is configured to parse the bitstream 21 (or generally encoded picture data 21) and, for example, perform entropy decoding to the encoded picture data 21 to obtain, for example, quantized coefficients 309 and / or decoded coding parameters (not shown in Figure 3), such as inter-prediction parameters (e.g., reference picture index and motion vector), intra-prediction parameters (e.g., intra-prediction mode or index), transformation parameters, quantization parameters, loop filter parameters, and / or other syntax elements. The entropy decoding unit 304 may be configured to apply a decoding algorithm or scheme corresponding to an encoding scheme such as those described with respect to the entropy encoding unit 270 of the encoder 20. The entropy decoding unit 304 may be further configured to provide the inter-prediction parameters, intra-prediction parameters, and / or other syntax elements to the mode application unit 360, and other parameters to other units of the decoder 30. The video decoder 30 may receive syntax elements at the video slice level and / or video block level. In addition to slices and their respective syntax elements, or as an alternative thereto, tile groups and / or tiles and their respective syntax elements may be received and / or used.

[0151] inverse quantization The inverse quantization unit 310 may be configured to receive quantization parameters (QP) (or generally information about inverse quantization) and quantized coefficients from the encoded picture data 21 (for example, by parsing and / or decoding by the entropy decoding unit 304), and to apply inverse quantization to the decoded quantized coefficients 309 based on the quantization parameters to obtain dequantized coefficients 311, which may also be called transformed coefficients 311. The inverse quantization process may include using quantization parameters determined by the video encoder 20 for each video block in the video slice (or tile or tile group) to determine the degree of quantization and, similarly, the degree of inverse quantization to be applied.

[0152] Inverse Transform The inverse transformation processing unit 312 may be configured to receive the dequantized coefficients 311, also called the transformation coefficients 311, and to apply a transformation to the dequantized coefficients 311 in order to obtain the reconstructed residual block 213 in the sample region. The reconstructed residual block 213 may also be called the transformation block 313. The transformation may be an inverse transformation, e.g., an inverse DCT, inverse DST, inverse integer transformation, or a conceptually similar inverse transformation process. The inverse transformation processing unit 312 may be further configured to receive transformation parameters or corresponding information from the encoded picture data 21 (e.g., by parsing and / or decoding, e.g., by the entropy decoding unit 304) in order to determine the transformation to be applied to the dequantized coefficients 311.

[0153] Reconstruction The reconstruction unit 314 (e.g., an adder or summer 314) may be configured to add the reconstructed residual block 313 to the predicted block 365 by adding the sample values ​​of the reconstructed residual block 313 to the sample values ​​of the predicted block 365, for example, to obtain the reconstructed block 315 in the sample region.

[0154] Filtering The loop filter unit 320 (either within or after the coding loop) is configured to filter the reconstructed block 315 to obtain a filtered block 321, for example, to smooth pixel transitions or otherwise improve video quality. The loop filter unit 320 may comprise 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, smoothing filter, or a co-filter, or any combination thereof. Although the loop filter unit 320 is shown in Figure 3 as an in-loop filter, in other configurations, the loop filter unit 320 may be implemented as a post-loop filter.

[0155] Decoded picture buffer The decoded video block 321 of the picture is then stored in a decoded picture buffer 330 that stores the decoded picture 331 as a reference picture for subsequent motion compensation for other pictures and / or for their respective output displays.

[0156] The decoder 30 is configured to output the decoded picture 311, for example via output 312, for presentation or viewing to the user.

[0157] prediction The inter-prediction unit 344 may be identical to the inter-prediction unit 244 (particularly the motion compensation unit), and the intra-prediction unit 354 may be functionally identical to the inter-prediction unit 254, performing partitioning or partitioning decisions and predictions based on partitioning and / or prediction parameters, or information received from the encoded picture data 21 (for example, by the entropy decoding unit 304, for example, by parsing and / or decoding). The mode application unit 360 may be configured to perform block-by-block predictions (intra or inter-predictions) based on the reconstructed picture, block, or each sample (filtered or unfiltered) to obtain a predicted block 365.

[0158] When a video slice is coded as an intra-coded (I) slice, the intra-prediction unit 354 of the mode-applying unit 360 is configured to generate a prediction block 365 for the picture block of the current video slice based on the signaled intra-prediction mode and data from previously decoded blocks of the current picture. When a video picture is coded as an inter-coded (i.e., B or P) slice, the inter-prediction unit 344 (e.g., a motion compensation unit) of the mode-applying unit 360 is configured to produce a prediction block 365 for the video block of the current video slice based on the motion vector and other syntax elements received from the entropy-decode unit 304. For inter-prediction, the prediction block may be produced from one of the reference pictures in one of the reference picture lists. The video decoder 30 may construct the reference frame lists, list 0 and list 1, using default configuration techniques based on the reference pictures stored in the DPB 330. In 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), the same or similar may apply depending on the embodiment, for example, video may be coded using I, P, or B tile groups and / or tiles.

[0159] The mode-applying unit 360 is configured to determine predictive information about the video block of the current video slice by parsing motion vectors or related information and other syntax elements, and to use the predictive information to create a predictive block for the current video block being decoded. For example, the mode-applying unit 360 uses some of the received syntax elements to determine the predictive mode used to code the video block of the video slice (e.g., intra or inter-predictive), the inter-predictive slice type (e.g., B-slice, P-slice, or GPB-slice), configuration information about one or more of the reference picture lists for the slice, the motion vector for each inter-encoded video block of the slice, the inter-predictive status for each intercoded video block of the slice, and other information in order to decode the video block in the current video slice. In 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), the same or similar may apply, for example, video may be coded using I, P, or B tile groups and / or tiles.

[0160] An embodiment of the video decoder 30, as shown in Figure 3, may be configured to divide and / or decode a picture by using slices (also called video slices), the picture may be divided into one or more (typically non-overlapping) slices, or decoded using them, each slice may comprise one or more blocks (e.g., CTUs).

[0161] Embodiments of the video decoder 30, as shown in Figure 3, may be configured to segment and / or decode a picture by using tile groups (also called video tile groups) and / or tiles (also called video tiles), wherein the picture may be segmented into one or more (typically non-overlapping) tile groups, and each tile group may comprise, for example, one or more blocks (e.g., CTUs) or one or more tiles, each tile may be, for example, rectangular in shape, and comprise one or more blocks (e.g., CTUs), for example, complete or fragmented blocks.

[0162] Other variations of the video decoder 30 can be used to decode the encoded picture data 21. For example, the decoder 30 can produce an output video stream without a loop filtering unit 320. For example, a non-transformation based decoder 30 can directly dequantize the residual signal for a given block or frame without an inverse transformation unit 312. In another implementation, the video decoder 30 may have an inverse quantization unit 310 and an inverse transformation unit 312 combined in a single unit.

[0163] It should be understood that in encoder 20 and decoder 30, the processing result of the current step may be further processed and then output to the next step. For example, after interpolation filtering, motion vector derivation, or loop filtering, further operations such as clipping or shifting may be performed on the processing result of interpolation filtering, motion vector derivation, or loop filtering.

[0164] It should be noted that further operations may be applied to the derived motion vectors of the current block (including, but not limited to, control point motion vectors in affine mode, subblock motion vectors in affine, planar, and ATMVP modes, time 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, then the range is -2^(bitDepth-1)~2^(bitDepth-1)-1, where "^" means exponentiation. For example, if bitDepth is set to equal 16, the range is -32768~32767, and if bitDepth is set to equal 18, the range is -131072~131071. For example, the value of a derived motion vector (e.g., the MV of four 4x4 subblocks in one 8x8 block) is constrained to not be greater than N pixels, such that the maximum difference between the integer parts of the four 4x4 subblock MVs is not greater than 1 pixel. Here, we provide two methods for constraining the motion vector according to bitDepth.

[0165] Method 1: Remove the overflow MSB (most significant bit) using flow arithmetic. 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) Here, mvx is the horizontal component of the motion vector of an image block or subblock, mvy is the vertical component of the motion vector of an image block or subblock, and ux and uy represent the intermediate values.

[0166] For example, if the value of mvx is -32769, after applying equations (1) and (2), the resulting value is 32767. In a computer system, decimal numbers are stored as two's complements. The two's complement of -32769 is 1,0111,1111,1111,1111 (17 bits), and then the MSB is discarded, so the resulting two's complement is 0111,1111,1111,1111 which is the same as the output by applying equations (1) and (2) (32767 in decimal). 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)

[0167] As represented by equations (5) to (8), the operation can be applied between the sum of mvp and mvd.

[0168] Method 2: Remove the 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) Here, vx is the horizontal component of the motion vector of an image block or sub-block, vy is the vertical component of the motion vector of an image block or sub-block, x, y, and z respectively correspond to the three input values of the MV clipping process, and the definition of the function Clip3 is as follows.

[0169]

Equation

[0170] Figure 4 is a schematic diagram of a video coding device 400 according to one embodiment of the disclosure. The video coding device 400 is suitable for implementing the disclosed embodiment as described herein. In one embodiment, the video coding device 400 may be a decoder, such as the video decoder 30 in Figure 1A, or an encoder, such as the video encoder 20 in Figure 1A.

[0171] The video coding device 400 comprises an inlet 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 exit port 450 (or output port 450) for transmitting data, and memory 460 for storing data. The video coding device 400 may also comprise optical-to-electrical (OE) and electrical-to-optical (EO) components coupled to the inlet port 410, receiver unit 420, transmitter unit 440, and exit port 450 for the exit or input of optical or electrical signals.

[0172] The processor 430 is implemented by hardware and software. The processor 430 may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), FPGAs, ASICs, and DSPs. The processor 430 communicates with an input port 410, a receiver unit 420, a transmitter unit 440, an output port 450, and 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 provides a considerable improvement to the functionality of the video coding device 400, resulting in the conversion of the video coding device 400 to different states. Alternatively, the coding module 470 is implemented as instructions stored in memory 460 and executed by the processor 430.

[0173] Memory 460 may comprise one or more disks, tape drives, and solid-state drives, and may be used as an overflow data storage device to store a program when such a program is selected for execution, and to store instructions and data to be read during program execution. Memory 460 may be, for example, volatile and / or non-volatile, and may be read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and / or static random-access memory (SRAM).

[0174] Figure 5 is a simplified block diagram of a device 500 that can be used as either or both of the source device 12 and destination device 14 from Figure 1, according to an exemplary embodiment.

[0175] The processor 502 within the device 500 can be a central processing unit. Alternatively, the processor 502 can be any other type of device, existing or to be developed in the future, capable of manipulating or processing information. The disclosed implementation can be carried out using a single processor, e.g., processor 502, as shown, but advantages in speed and efficiency can be achieved using one or more processors.

[0176] The memory 504 within the device 500 can be a read-only memory (ROM) device or a random access memory (RAM) device in one implementation. Any other suitable type of storage device can be used as memory 504. Memory 504 may contain code and data 506 accessed by the processor 502 using the bus 512. Memory 504 may further contain an operating system 508 and an application program 510, the application program 510 including at least one program that enables the processor 502 to perform the method described herein. For example, the application program 510 may include applications 1 through N, and applications 1 through N further include video coding applications that perform the method described herein.

[0177] The device 500 may also include one or more output devices, such as a display 518. The display 518 may, in one example, be a touch-sensitive display that combines the display with a touch-sensitive element that is operable to sense touch input. The display 518 can be coupled to the processor 502 via the bus 512.

[0178] Although described here as a single bus, the bus 512 of device 500 can consist of multiple buses. Furthermore, the secondary storage device 514 can be directly coupled to other components of device 500 or accessed via a network, and can consist of a single integrated unit such as a memory card, or multiple units such as multiple memory cards. Thus, device 500 can be implemented in a wide variety of configurations.

[0179] Chroma component subsampling In video coding, there is typically one luminance component (Y) and two chrominance components (Cb and Cr) for the input video. In practice, the chroma component is usually subsampled to reduce storage and transition bandwidth for the video.

[0180] There are several chroma subsampling formats. In some cases, there is a single chroma subsampling format that does not require chroma subsampling for video, such as the chroma subsampling format 4:4:4. In the chroma subsampling format 4:4:4, the three components Y, U, and V are equally distributed within the frame, as shown in the example in Figure 6. In one example, assuming the size of the chroma component is 1 within the video, the total size of the video is 3.

[0181] In practice, one chroma subsampling format, 4:2:0, is widely used, where the chroma component is subsampled by half horizontally and vertically to the lumen component, as shown in the example in Figure 7, and the size of Cb or Cr is 1 / 4 the size of the lumen component. Thus, in the 4:2:0 format, the total size of the video is 1(Y) + 0.25(Cb) + 0.25(Cr) = 1.5 times the size of the lumen component. Compared to the 4:4:4 chroma subsampling format, the 4:2:0 format saves half the size required for storing or transitioning video streams.

[0182] In another example, the chroma subsampling format 4:2:2 is disclosed, where the chroma component is horizontally subsampled as shown in the example in Figure 8. In this case, the size of Cb or Cr is half that of the chroma component. Thus, the total size of the video in this format is 1(Y) + 0.5(Cb) + 0.5(Cr) = 2 times the size of the chroma component. Compared to the 4:4:4 chroma subsampling format, the 4:2:2 format saves 1 / 3 of the size required for storage or transitions.

[0183] In these examples, the size of the luma component is assumed to be 1 within the video.

[0184] In one example presented in ITU-T JVET O2001 (link is http: / / phenix.it-sudparis.eu / jvet / doc_end_user / documents / 15_Gothenburg / wg11 / JVET-O2001-v14.zip), the variables and terms associated with these arrays are called chroma (or L or Y) and chroma, where the two chroma arrays are called Cb and Cr.

[0185] The variables SubWidthC and SubHeightC depend on the chroma format sampling structure specified through chroma_format_idc and separate_colour_plane_flag, and are specified in Table 1 below. Other values ​​for chroma_format_idc, SubWidthC, and SubHeightC may be specified in the future by ITU-T | ISO / IEC.

[0186] [Table 8]

[0187] `chroma_format_idc` specifies chromasampling relative to chromasampling (as shown in Table 1 and related paragraphs). The value of `chroma_format_idc` should be within the range of 0 to 3.

[0188] In monochromatic sampling, there is nominally only one sample array, which is considered a lumen array.

[0189] In 4:2:0 sampling, each of the two chroma arrays has half the height and half the width of the chroma array.

[0190] In 4:2:2 sampling, each of the two chroma arrays has the same height and half the width of the chroma array.

[0191] In 4:4:4 sampling, the following applies depending on the value of separate_colour_plane_flag: - If separate_colour_plane_flag is equal to 0, then each of the two chroma arrays has the same height and width as the luma array. - Otherwise (separate_colour_plane_flag is equal to 1), the three color planes are processed separately as monochrome sampled pictures.

[0192] The number of bits required for each representation of a sample in the rumor and chroma arrays within a video sequence ranges from 8 to 16, and the number of bits used in the rumor array may differ from the number of bits used in the chroma array.

[0193] When the value of chroma_format_idc is equal to 1, the nominal vertical and horizontal relative positions of the chroma and chroma samples in the picture are shown in Figure 7. Alternative chroma sample relative positions may be indicated within the video utility information.

[0194] When the value of chroma_format_idc is equal to 2, the chroma sample is placed in the same location as the corresponding chroma sample, and its nominal position in the picture is as shown in Figure 8.

[0195] When the value of chroma_format_idc is equal to 3, all array samples are placed in the same location for all cases of the picture, and the nominal positions within the picture are as shown in Figure 6.

[0196] Angle intra-prediction modes and their corresponding directional interpretations In one example shown in Figure 9, the angle intra-prediction modes are represented by solid lines (from 2 to 66) with arrows. Among these, modes 18 and 50 correspond to the horizontal and vertical prediction directions, respectively. Relative to the horizontal direction, modes 2 and 34 correspond to 45° and -45°, respectively. Relative to the vertical direction, modes 66 and 34 correspond to 45° and -45°.

[0197] In some examples, the angles of these modes (e.g., inputs 2, 18, 34, 50, 66), which have modes as inputs and distances as outputs, are implicitly defined using the distance values, as shown in Table 2.

[0198] [Table 9]

[0199] The corresponding degree for Mode X is: degree = arctan(output(x) / 32) It can be derived as follows:

[0200] In one example, input mode 2 will output a value of 32, and the corresponding degree for mode 2 is 45°. Similarly, modes 18, 34, 50, and 66 will output values ​​of 0, -32, 0, and 32, and their corresponding degrees are 0, -45°, 0, and 45°, respectively. It should be noted that both mode 18 (horizontal prediction) and 50 (vertical prediction) correspond to 0 degrees, and mode 34 corresponds to the overlapping -45° relative to the two 0-degree modes.

[0201] As shown in Figure 10, for modes 0 to 34, adjacent sides of a desired angle are parallel to the horizontal, while opposite sides of a desired angle are parallel to the vertical. The desired angles corresponding to mode 8 are shown on the left side of Figure 10. For modes 34 to 66, adjacent sides of a desired angle are parallel to the vertical, while opposite sides of a desired angle are parallel to the horizontal.

[0202] In some examples, some modes (e.g., modes 3, 4, 6...26) do not have outputs that are multiples of 32. Among modes 2, 18, 34, 50, and 66, the corresponding degrees for these modes are not uniformly distributed between 45 degrees. As shown in Figure 9, modes are more closely defined when their corresponding angles are closer to horizontal (mode 18) and vertical (mode 50) degrees.

[0203] In some examples, certain intra-prediction modes (e.g., 8, 28, 40, and 60...) will output values ​​that are multiples of 16 (but not 32), corresponding to angles where the opposite side is half of the adjacent side (the tangent function for these angles is 0.5 or -0.5).

[0204] In some examples, there are wide-angle modes ranging from -1 to -14 and from 67 to 80. When the block aspect ratio is not 1:1, these modes are not directly coded but are mapped.

[0205] The mapping rule is defined as follows, using input nW as the block width, nH as the block height, and predModeIntra as the input angle mode:

[0206] The variable whRatio is set to equal Abs(Log2(nW / nH)).

[0207] For non-square blocks (where nW is not equal to nH), the intra prediction mode predModeIntra is modified as follows: - If all of the following conditions (these conditions are used to determine whether or not the wide-angle mapping process should be applied) are true, then predModeIntra is set to equal to (predModeIntra + 65). - nW is greater than nH, - predModeIntra is 2 or greater, - predModeIntra is (whRatio > 1) ? (8 + 2 * whRatio) : less than 8. - Otherwise, if all of the following conditions (which are used to determine whether or not the wide-angle mapping process should be applied) are true, predModeIntra is set to equal to (predModeIntra - 67). - nH is greater than nW, - predModeIntra is 66 or less, - predModeIntra is (whRatio > 1) ? (60 - 2 * whRatio) : greater than 60.

[0208] Taking a block with an aspect ratio of 1:2 (where the block width is half the height) as an example, predModeIntra modes 61 to 66 will be mapped from -6 to -1 when the following conditions are met. - nH is greater than nW, - predModeIntra is 66 or less, - predModeIntra is (whRatio > 1) ? (60 - 2 * whRatio) : greater than 60, where whRatio = Abs( Log2( nW / nH ) ) = 1.

[0209] Derivation of chromatic intra-predictive modes when chromatic components are subsampled horizontally or vertically. In some examples, for a 4:2:2 chroma subsampling format, a mapping table may be defined to derive the final chroma intra-angle mode, where the original chroma angle prediction mode is adjusted based on the ratio changed due to subsampling.

[0210] In one example shown in Figure 10, the block without chroma subsampling (left side) has the same width and height. Modes 2, 8, 18, 34, 50, and 66 are labeled using their predicted directions. When the chroma component is subjected to a 4:2:2 chroma subsample format (i.e., as shown in Figure 8, the chroma component is subsampled only horizontally, and the chroma samples are aligned with the lumens samples every two columns), the width of the chroma component is half the width of the lumens component.

[0211] In this case, the aspect ratio of the chroma block is 1:2 due to chroma subsampling. Therefore, the original mode is adjusted (mapped) according to the horizontally subsampled chroma component. In this case, mode 2 is mapped to 61 to adjust for the halved reduction in the horizontal direction. Since the aspect ratio of the subsampled block is 1:2, and the mapped mode 61 satisfies the conditions for the wide-angle mapping process, the mapped mode 61 will be further mapped to mode -6 according to the wide-angle mapping process.

[0212] Mode-6 corresponds to 64 output values ​​according to Table 2. Therefore, the corresponding degree of the final angle after chroma subsampling is: degree = arctan(64 / 32) That is the case.

[0213] The tangent value of this angle is twice that of mode 2, which reflects that the adjacent edges in mode 2 were halved for chroma subsampling.

[0214] (As shown on the left in Figure 10) Mode 8 is mapped to Mode 2 because the position of half the width corresponds to Mode 8, and Mode 8 corresponds to an angle of 45° due to its width in the horizontal direction. Similarly, Modes 34 and 60 are mapped to 40 and 60, respectively. In these examples, the horizontal and vertical prediction modes, whose degree is 0, are not mapped to other modes; that is, the horizontal / vertical modes are still mapped to the same mode.

[0215] To map the intra-prediction mode when the chroma component is subsampled (for example, chroma subsampling format 4:2:2), the mapping table is defined as follows:

[0216] [Table 10]

[0217] In one implementation of the present invention, it is proposed to replace the mapping of modes 2 to 7 with 60 to 65, as defined in Table 4.

[0218] [Table 11]

[0219] In the example above, mode 2 will be mapped to 61. In this embodiment, mode 2 will be mapped to mode 60, as shown in Figure 10.

[0220] In one implementation of the present invention, it is proposed to replace the mapping of modes 2 to 7 with 61 to 66, which are the same as modes 2 to 7 in Table 3, as defined in Table 5.

[0221] [Table 12]

[0222] In one implementation of the present invention, it is proposed to map modes 8 through 18 to the following modes, as defined in Table 6.

[0223] [Table 13]

[0224] In one implementation of the present invention, Table 7 below is used to illustrate how the mapped modes are derived.

[0225] [Table 14]

[0226] The left side represents 2 to 18 input modes, with each mode corresponding to a tangent value and angle. Without subsampling, the angles for these modes can be defined as follows: degree = arctan(output(x) / 32)

[0227] For modes 2 to 34, the scaling factor 32 may be regarded as the width shown in FIG. 10. For those modes, the adjacent sides of the desired angle are parallel to the horizontal direction, while the opposite sides of the desired angle are parallel to the vertical direction. The desired angle corresponding to mode 8 is shown in the left sub - figure of FIG. 10. In contrast, for modes 34 to 66, since (the angle corresponding to mode 34 is the overlapping angle (-45 degrees) related to both the horizontal and vertical directions), the adjacent sides of the desired angle are parallel to the vertical direction, while the opposite sides of the desired angle are parallel to the horizontal direction.

[0228] Due to chroma sub - sampling, for modes 2 to 34, since the adjacent sides (parallel to the width) are halved, the tangent value with sub - sampling is doubled, and for modes 34 to 66, since the opposite sides are halved, the tangent value with sub - sampling is halved.

[0229] In one example, the doubled tangent values are listed for each mode on the right side of Table 7. However, the angle is not linearly proportional to the tangent value. Therefore, these doubled tangent values need to be converted back to angle values. Using the converted angle values on the right side with chroma sub - sampling, the mode with the closest angle on the left side of Table 7 is the output mode.

[0230] In summary, to find the corresponding mapping mode, the reference table is first generated using the following steps with the input mode X. · Obtain the output value according to Table 2. · Alternatively or in addition, calculate the tangent value of this mode as output(X) / 32. · Alternatively or in addition, calculate the angle using the derived tangent value, for example, arctan (output(x) / 32). ·As an alternative or in addition, use the range of input mode X to generate a reference table using the three steps above, where X belongs to 2..18, as shown on the left side of Table 7 including columns for tangent values, angle values, and input mode.

[0231] The following steps are applied to derive the mode mapped using input mode X. ·As an alternative or in addition, double the tangent value of mode X as 2*output(X) / 32. ·As an alternative or in addition, use the doubled tangent value to calculate the angle in chroma subsampling format 4:2:2, e.g., arctan(2*output(x) / 32). ·As an alternative or in addition, find the closest angle in the reference table (e.g., the angle list without chroma subsampling in Table 7) according to the calculated angle value in chroma subsampling format 4:2:2. ·As an alternative or in addition, pick up the corresponding output mode according to the closest angle in the reference table.

[0232] For the sake of brevity, the above process is referred to as the process for deriving the output mode.

[0233] In one example, after the reference table is generated, input mode 10 derives its output mode as follows. ·Double the tangent value of mode 10 as 2*12 / 32 = 0.75. ·Use the doubled tangent value to calculate the angle in chroma subsampling format 4:2:2, e.g., arctan(0.75) = 36.8699°. ·Find the closest angle 35.70669° in the reference table according to the calculated angle value 36.8699°. ·Pick up the corresponding output mode 5 according to the closest angle 35.70669° in the reference table.

[0234] Therefore, input mode 10 is mapped to mode 5.

[0235] In one implementation of the present invention, it is proposed to map modes 19 to 28 to the following modes, as defined in Table 8.

[0236] [Table 15]

[0237] In one implementation of the present invention, Table 9 below is used to illustrate how the mapped modes are derived.

[0238] [Table 16]

[0239] Table 9 can also be derived using the process for deriving output modes, as defined in the previous embodiment. In this example, input modes 19 through 34 are used when generating the reference table (left side of Table 9).

[0240] In one implementation of the present invention, it is proposed to map modes 29 to 34 to the following modes, as defined in Table 10.

[0241] [Table 17]

[0242] In one implementation of the present invention, Table 11 below is used to illustrate how the mapped modes are derived.

[0243] [Table 18]

[0244] In one example, Table 11 can be derived using the process for deriving output modes as defined in the previous embodiments, except for the following aspects. · When generating the reference table, input modes from 29 to 40 are used. · For modes 29 to 34, one additional step is required to derive the output mode. The angle corresponding to the value of 2*tangent(output(x) / 32) is less than -45° (i.e., the absolute value of the angle is greater than 45°). Since the smallest angle that can be derived is -45°, these (less than -45°) angles cannot be directly used. In this case, their complementary angles are used, and the angles to be mapped face the upper boundary of the current block (instead of the current left boundary). Therefore, the adjacent and opposite sides of the mapped angle are exchanged, and thus the tangent value of their complementary angles, 1 / 2*tangent(output(x) / 32), is used to derive the correct angle to find the closest angle within the reference table.

[0245] In one implementation of the present invention, it is proposed to map modes 35 to 50 in the following modes as defined in Table 12.

[0246] [Table 19]

[0247] In one implementation of the present invention, the following Table 13 is used to represent how the mapped modes are derived.

[0248] [Table 20]

[0249] Table 13 can be derived using a process for deriving output modes, but with the following modifications. When generating a reference table, input modes 35 through 50 are used. Modes 35 through 50 correspond to angles where the opposite edge is the upper boundary of the current block. After chroma subsampling, the opposite edges are halved using the 4:2:2 chroma subsampling format, so the corresponding tangent values ​​are halved (instead of being doubled in Table 7).

[0250] For example, mode 36 can also be mapped to 42 by considering the following mapping table, as shown in Table 2.

[0251] [Table 21]

[0252] From the perspective of mode 36, opposite sides of a corresponding angle are parallel to the horizontal direction, and adjacent sides of a corresponding angle are parallel to the vertical direction. Due to chroma subsampling, the horizontal direction is reduced by half, i.e., opposite sides of a corresponding angle are reduced by half. This is equivalent to reducing its output value by half, which means that its output value is now -26 / 2 = -13. Since -13 has two equivalent nearest output values, -12 and -14, it can be mapped to either mode 41 or 42.

[0253] For the same reason, modes 39, 41, 43, 47, and 49 can be mapped to either 43 or 44, 44 or 45, 45 or 46, 48 or 49, or 49 or 50, respectively. Table 14 summarizes the possible mapping modes and how they are derived.

[0254] [Table 22]

[0255] In one implementation of the present invention, it is proposed to map modes 51 to 66 to the following modes, as defined in Table 15.

[0256] [Table 23]

[0257] In one implementation of the present invention, Table 16 below is used to illustrate how the mapped modes are derived.

[0258] [Table 24]

[0259] Similar to Table 13, Table 16 can be derived using a process for deriving output modes, but with the following modifications. When generating a reference table, input modes 50 through 66 are used. Modes 51 through 66 correspond to angles where the opposite edge is the upper boundary of the current block. After chroma subsampling, the opposite edges are halved using the 4:2:2 chroma subsampling format, so the corresponding tangent values ​​are halved (instead of being doubled in Table 7).

[0260] Similar to Table 14, as shown in Table 17, some of the modes among modes 51 to 66 may have alternative mapped modes.

[0261] [Table 25]

[0262] In the embodiments described above, many embodiments are represented as a chroma subsampling mode 4:2:2, i.e., a mapping mode for subsampling only half of the chroma component in the horizontal direction. It should be noted that similar methods can be proposed for chroma subsampling formats in which the chroma component is subsampled vertically.

[0263] In some cases, it is not necessary to perform intra-predictive mode mapping for chroma subsampling formats where the block aspect ratio does not change. For example, with a 4:2:0 chroma subsampling format, the chroma component is subsampled both horizontally and vertically, so the block aspect ratio does not change, and therefore mode mapping is not necessary.

[0264] In some examples, the above embodiments can be combined as long as one input mode X has one output mode Y. For example, Table 18 below shows one of the combinations of the proposed embodiments.

[0265] [Table 26]

[0266] In some examples, one or any combination of the modes disclosed in the embodiments described above (for example, Tables 2 to 18) may be combined to form a mode mapping relationship.

[0267] Example 1. A coding method performed by a decoding device, Steps to obtain the video bitstream, The steps include: decoding the video bitstream to obtain the initial intra-predicted mode value for the chroma component of the current coding block; The steps include determining whether the ratio between the width of the current coding block relative to the lumern component and the width of the current coding block relative to the chromern component is equal to a threshold (or determining whether the ratio between the height of the current coding block relative to the lumern component and the height of the current coding block relative to the chromern component is equal to a threshold), When it is determined that the ratio is equal to a threshold, the steps include obtaining the mapped intra-predictive mode value for the chroma component of the current coding block according to the default mapping relationship and initial intra-predictive mode value, A method comprising the steps of obtaining predicted sample values ​​for the chroma component of the current coding block according to mapped intra-predicted mode values.

[0268] Example 2. The method from Example 1, but with a threshold of 2 or 0.5.

[0269] Example 3. The following table represents the default mapping relationships, i.e.,

[0270] [Table 27]

[0271] or

[0272] [Table 28]

[0273] The method used in Example 1 or 2, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0274] Example 4. The following table represents the default mapping relationships, i.e.,

[0275] [Table 29]

[0276] One of the methods from Examples 1 to 3 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0277] Example 5. The following table represents the default mapping relationships, i.e.,

[0278] [Table 30]

[0279] One of the methods from Examples 1 to 4 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0280] Example 6. The following table represents the default mapping relationships, i.e.,

[0281] [Table 31]

[0282] One of the methods from Examples 1 to 5 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0283] Example 7. The following table represents the default mapping relationships, i.e.,

[0284] [Table 32]

[0285] One of the methods from Examples 1 to 6 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0286] Example 8. The following table represents the default mapping relationships, i.e.,

[0287] [Table 33]

[0288] One of the methods from Examples 1 to 6 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0289] Example 9. The following table represents the default mapping relationships, i.e.,

[0290] [Table 34]

[0291] One of the methods from Examples 1 to 6 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0292] Example 10. The following table represents the default mapping relationships, i.e.,

[0293] [Table 35]

[0294] One of the methods in Examples 1 through 6, 8, and 9 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0295] Example 11. The following table represents the default mapping relationships, i.e.,

[0296] [Table 36]

[0297] One of the methods in Examples 1 through 6, 8, and 9 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0298] Example 12. The following table represents the default mapping relationships, i.e.,

[0299] [Table 37]

[0300] One of the methods from Examples 1 to 6 and 8 to 11 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0301] Example 13. The following table represents the default mapping relationships, i.e.,

[0302] [Table 38]

[0303] One of the methods from Examples 1 to 6 and 8 to 11 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0304] Example 14. The following table represents the default mapping relationships, i.e.,

[0305] [Table 39]

[0306] One of the methods from Examples 1 to 6 and 8 to 13 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0307] Example 15. The following table represents the default mapping relationships, i.e.,

[0308] [Table 40]

[0309] One of the methods from Examples 1 to 6 and 8 to 13 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0310] Example 16. The following table represents the default mapping relationships, i.e.,

[0311] [Table 41]

[0312] One of the methods from Examples 1 to 6 and 8 to 15 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0313] Example 17. The following table represents the default mapping relationships, i.e.,

[0314] [Table 42]

[0315] One of the methods from Examples 1 to 6 and 8 to 15 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0316] Example 18. The following table represents the default mapping relationships, i.e.,

[0317] [Table 43]

[0318] One of the methods from Examples 1 to 6 and 8 to 17 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0319] Example 19. The following table represents the default mapping relationships, i.e.,

[0320] [Table 44]

[0321] One of the methods from Examples 1 to 6 and 8 to 17 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0322] Example 20. The following table represents the default mapping relationships, i.e.,

[0323] [Table 45]

[0324] One of the methods from Examples 1 to 19 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0325] Example 21. The following table represents the default mapping relationships, i.e.,

[0326] [Table 46]

[0327] One of the methods from Examples 1 to 19 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0328] Example 22. The following table represents the default mapping relationships, i.e.,

[0329] [Table 47]

[0330] One of the methods from Examples 1 to 19 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0331] Example 23. The following table represents the default mapping relationships, i.e.,

[0332] [Table 48]

[0333] One of the methods from Examples 1 to 19 and 21 to 22 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0334] Example 24. The following table represents the default mapping relationships, i.e.,

[0335] [Table 49]

[0336] One of the methods from Examples 1 to 19 and 21 to 22 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0337] Example 25. The following table represents the default mapping relationships, i.e.,

[0338] [Table 50]

[0339] One of the methods from Examples 1 to 19 and 21 to 24 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0340] Example 26. The following table represents the default mapping relationships, i.e.,

[0341] [Table 51]

[0342] One of the methods from Examples 1 to 19 and 21 to 24 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0343] Example 27. The following table represents the default mapping relationships, i.e.,

[0344] [Table 52]

[0345] One of the methods from Examples 1 to 19 and 21 to 26 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0346] Example 28. The following table represents the default mapping relationships, i.e.,

[0347] [Table 53]

[0348] One of the methods from Examples 1 to 19 and 21 to 26 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0349] Example 29. The following table represents the default mapping relationships, i.e.,

[0350] [Table 54]

[0351] One of the methods from Examples 1 to 19 and 21 to 28 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0352] Example 30. The following table represents the default mapping relationships, i.e.,

[0353] [Table 55]

[0354] One of the methods from Examples 1 to 19 and 21 to 28 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0355] Example 31. The following table represents the default mapping relationships, i.e.,

[0356] [Table 56]

[0357] One of the methods from Examples 1 to 19 and 21 to 30 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0358] Example 32. The following table represents the default mapping relationships, i.e.,

[0359] [Table 57]

[0360] One of the methods from Examples 1 to 19 and 21 to 30 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0361] Example 33. A coding method performed by a decoding device, Steps to obtain the video bitstream, The steps include: decoding the video bitstream to obtain the initial intra-predicted mode value for the chroma component of the current coding block; The steps include: decoding the video bitstream to obtain the value of the chroma format display information for the current coding block; When the value of the chroma format display information for the current coding block is equal to the default value, the steps include obtaining the mapped intra-prediction mode value for the chroma component of the current coding block according to the default mapping relationship and initial intra-prediction mode value, A method comprising the steps of obtaining predicted sample values ​​for the chroma component of the current coding block according to mapped intra-predicted mode values.

[0362] Example 34. The method in Example 33, where the default value is 2 or 1.

[0363] Example 35. The following table represents the default mapping relationships, i.e.,

[0364] [Table 58]

[0365] or

[0366] [Table 59]

[0367] The method used in Example 31 or 32, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0368] Example 36. The following table represents the default mapping relationships, i.e.,

[0369] [Table 60]

[0370] One of the methods from Examples 33 to 35 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0371] Example 37. The following table represents the default mapping relationships, i.e.,

[0372] [Table 61]

[0373] One of the methods from Examples 33 to 36 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0374] Example 38. The following table represents the default mapping relationships, i.e.,

[0375] [Table 62]

[0376] One of the methods from Examples 33 to 37 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0377] Example 39. The following table represents the default mapping relationships, i.e.,

[0378] [Table 63]

[0379] One of the methods from Examples 33 to 38 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0380] Example 40. The following table represents the default mapping relationships, i.e.,

[0381] [Table 64]

[0382] One of the methods from Examples 33 to 38 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0383] Example 41. The following table represents the default mapping relationships, i.e.,

[0384] [Table 65]

[0385] One of the methods from Examples 33 to 38 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0386] Example 42. The following table represents the default mapping relationships, i.e.,

[0387] [Table 66]

[0388] In any of the following ways, as shown in Examples 33 to 38, 40, and 41, mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0389] Example 43. The following table represents the default mapping relationships, i.e.,

[0390] [Table 67]

[0391] In any of the following ways, as shown in Examples 33 to 38, 40, and 41, mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0392] Example 44. The following table represents the default mapping relationships, i.e.,

[0393] [Table 68]

[0394] One of the methods used in Examples 33 to 38 and 40 to 43 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0395] Example 45. The following table represents the default mapping relationships, i.e.,

[0396] [Table 69]

[0397] One of the methods used in Examples 33 to 38 and 40 to 43 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0398] Example 46. The following table represents the default mapping relationships, i.e.,

[0399] [Table 70]

[0400] One of the methods used in Examples 33 to 38 and 40 to 45, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0401] Example 47. The following table represents the default mapping relationships, i.e.,

[0402] [Table 71]

[0403] One of the methods used in Examples 33 to 38 and 40 to 45, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0404] Example 48. The following table represents the default mapping relationships, i.e.,

[0405] [Table 72]

[0406] One of the methods used in Examples 33 to 38 and 40 to 47, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0407] Example 49. The following table represents the default mapping relationships, i.e.,

[0408] [Table 73]

[0409] One of the methods used in Examples 33 to 38 and 40 to 47, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0410] Example 50. The following table represents the default mapping relationships, i.e.,

[0411] [Table 74]

[0412] One of the methods used in Examples 33 to 38 and 40 to 49, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0413] Example 51. The following table represents the default mapping relationships, i.e.,

[0414] [Table 75]

[0415] One of the methods used in Examples 33 to 38 and 40 to 49, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0416] Example 52. The following table represents the default mapping relationships, i.e.,

[0417] [Table 76]

[0418] One of the methods from Examples 33 to 51 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0419] Example 53. The following table represents the default mapping relationships, i.e.,

[0420] [Table 77]

[0421] One of the methods from Examples 33 to 51 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0422] Example 54. The following table represents the default mapping relationships, i.e.,

[0423] [Table 78]

[0424] One of the methods from Examples 33 to 51 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0425] Example 55. The following table represents the default mapping relationships, i.e.,

[0426] [Table 79]

[0427] In one of the methods from Examples 33 to 51 and 53 to 54, mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0428] Example 56. The following table represents the default mapping relationships, i.e.,

[0429] [Table 80]

[0430] In one of the methods from Examples 33 to 51 and 53 to 54, mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0431] Example 57. The following table represents the default mapping relationships, i.e.,

[0432] [Table 81]

[0433] One of the methods from Examples 33 to 51 and 53 to 56 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0434] Example 58. The following table represents the default mapping relationships, i.e.,

[0435] [Table 82]

[0436] One of the methods from Examples 33 to 51 and 53 to 56 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0437] Example 59. The following table represents the default mapping relationships, i.e.,

[0438] [Table 83]

[0439] One of the methods from Examples 33 to 51 and 53 to 58 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0440] Example 60. The following table represents the default mapping relationships, i.e.,

[0441] [Table 84]

[0442] One of the methods from Examples 33 to 51 and 53 to 58 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0443] Example 61. The following table represents the default mapping relationships, i.e.,

[0444] [Table 85]

[0445] One of the methods from Examples 33 to 51 and 53 to 60 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0446] Example 62. The following table represents the default mapping relationships, i.e.,

[0447] [Table 86]

[0448] One of the methods from Examples 33 to 51 and 53 to 60 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0449] Example 63. The following table represents the default mapping relationships, i.e.,

[0450] [Table 87]

[0451] One of the methods from Examples 33 to 51 and 53 to 62 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0452] Example 64. The following table represents the default mapping relationships, i.e.,

[0453] [Table 88]

[0454] One of the methods from Examples 33 to 51 and 53 to 62 is used, where mode X represents the initial intra-predicted mode value and mode Y represents the mapped intra-predicted mode value.

[0455] Example 65. A decoder (30) equipped with a processing circuit for performing one of the methods from Examples 1 to 64.

[0456] Example 66. A computer program product comprising program code for performing one of the methods described in Examples 1 through 64.

[0457] Example 67. A decoder, One or more processors, A decoder comprising a non-temporary computer-readable storage medium coupled to a processor and storing a program for execution by the processor, wherein the program, when executed by the processor, configures the decoder to perform a method according to any one of Examples 1 to 64.

[0458] The following describes the encoding method, the decoding method as shown in the embodiments described above, and the application of systems using them.

[0459] Figure 11 is a block diagram representing a content supply system 3100 for realizing a content distribution service. This content supply system 3100 includes a capture device 3102, a terminal device 3106, and optionally a display 3126. The capture device 3102 communicates with the terminal device 3106 over a communication link 3104. The communication link may include the communication channel 13 described above. The communication link 3104 includes, but is not limited to, Wi-Fi, Ethernet, cable, wireless (3G / 4G / 5G), USB, or any combination thereof, or similar.

[0460] The capture device 3102 may generate data and encode the data using an encoding method as shown in the embodiments described above. Alternatively, the capture device 3102 may deliver the data to a streaming server (not shown in the figure), which encodes the data and transmits the encoded data to the terminal device 3106. The capture device 3102 includes, but is not limited to, a camera, a smartphone or tablet, a computer or laptop, a video conferencing system, a PDA, a vehicle-mounted device, or any combination thereof, or similar. For example, the capture device 3102 may include a source device 12 as described above. When the data includes video, the video encoder 20 contained within the capture device 3102 may actually perform the video encoding process. When the data includes audio (i.e., speech), the audio encoder contained within the capture device 3102 may actually perform the audio encoding process. In some practical scenarios, the capture device 3102 delivers the encoded video and audio data by multiplexing them together. In other practical scenarios, for example, in a video conferencing system, the encoded audio data and encoded video data are not multiplexed. The capture device 3102 delivers the encoded audio data and encoded video data separately to the terminal device 3106.

[0461] In the content supply system 3100, the terminal device 310 receives and plays back encoded data. The terminal device 3106 can be a data receiving and recovery capable device capable of decoding the encoded data described above, such as a smartphone or tablet 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, a vehicle-mounted device 3124, or any combination thereof, or similar. For example, the terminal device 3106 may include the destination device 14 as described above. When the encoded data includes video, the video decoder 30 contained within the terminal device is prioritized to perform video decoding. When encoded data includes audio, the audio decoder included in the terminal device is prioritized to perform the audio decoding process.

[0462] For terminal devices having a display, such as a smartphone or tablet 3108, a computer or laptop 3110, a network video recorder (NVR) / digital video recorder (DVR) 3112, a TV 3114, a personal digital assistant (PDA) 3122, or a vehicle-mounted device 3124, the terminal device can supply decoded data to its display. For terminal devices not equipped with a display, such as an STB 3116, a video conferencing system 3118, or a video surveillance system 3120, an external display 3126 is made contact thereto to receive and display the decoded data.

[0463] When each device in this system performs encoding or decoding, a picture encoding device or a picture decoding device can be used, as shown in the embodiments described above.

[0464] Figure 12 shows the structure of an example terminal device 3106. After the terminal device 3106 receives a stream from the capture device 3102, the protocol progression unit 3202 analyzes the transmission protocol of the stream. The protocol includes, but is not limited to, Real Time Streaming Protocol (RTSP), Hyper Text Transfer Protocol (HTTP), HTTP Live Streaming Protocol (HLS), MPEG-DASH, Real-time Transport Protocol (RTP), Real Time Messaging Protocol (RTMP), or any combination thereof, or similar.

[0465] After the protocol processing 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 described above, in some practical scenarios, for example, in a video conferencing system, the encoded audio data and encoded video data are not multiplexed. In this situation, the encoded data is transmitted to the video decoder 3206 and audio decoder 3208 without passing through the demultiplexing unit 3204.

[0466] Through demultiplexing, a video elementary stream (ES), an audio ES, and optionally a subtitle are generated. A video decoder 3206, including a video decoder 30 as described in the embodiments described above, decodes the video ES using the decoding method shown in the embodiments described above to generate video frames and supplies this data to the synchronization unit 3212. An audio decoder 3208 decodes the audio ES to generate audio frames and supplies this data to the synchronization unit 3212. Alternatively, video frames may be stored in a buffer (not shown in Figure 12) before supplying them to the synchronization unit 3212. Similarly, audio frames may be stored in a buffer (not shown in Figure 12) before supplying them to the synchronization unit 3212.

[0467] The synchronization unit 3212 synchronizes video frames and audio frames and supplies video / audio to the video / audio display 3214. For example, the synchronization unit 3212 synchronizes the presentation of video and audio information. The information may be coded within the syntax using timestamps related to the presentation of coded audio and visual data, and timestamps related to the delivery of the data stream itself.

[0468] If the stream contains subtitles, the subtitle decoder 3210 decodes the subtitles, synchronizes them with the video and audio frames, and supplies the video / audio / subtitle to the video / audio / subtitle display 3216.

[0469] The present invention is not limited to the systems described above, and either the picture encoding device or the picture decoding device in the embodiments described above can be incorporated into other systems, such as automotive systems.

[0470] 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 precisely defined, and additional operations such as exponentiation and real-valued division are defined. The numbering and counting conventions generally start from 0, for example, “1st” is equivalent to the 0th, “2nd” is equivalent to the 1st, and so on.

[0471] Arithmetic operators The following arithmetic operators are defined as follows: + Addition. - Subtraction (as a two-argument operator) or sign reversal (as a unary prefix operator). * Includes multiplication and matrix multiplication. x y Exponentiation. Specifies x raised to the power of y. In other contexts, such notation is used to make a superscript unintended for interpretation as an exponentiation. Integer division with the result truncated to zero. For example, 7 / 4 and -7 / -4 are truncated to 1, and -7 / 4 and 7 / -4 are truncated to -1. ÷ is used to indicate division in mathematical expressions where rounding or truncation is not intended.

[0472]

number

[0473] Used to represent division in mathematical expressions where truncation or rounding is not intended.

[0474]

number

[0475] The sum of f(i) such that i can take all integer values ​​from x to y, including y. The x % y method. Defined only for integers x and y such that x >= 0 and y > 0, this method provides the remainder when x is divided by y.

[0476] Logical operators The following logical operators are defined as follows: The Boolean logical AND operation between x and y. x || y: The Boolean "logical OR" of x and y. ! The "negation" in Boolean logic. x ? y : If zx is TRUE, i.e., not equal to 0, evaluate to the value of y; otherwise, evaluate to the value of z.

[0477] Relational operators The following relational operators are defined as follows: It is larger than >. >= That's all. < is smaller than. <= Below. == equal. != Not equal.

[0478] When a relational operator is applied to a syntax element or variable that is assigned the value "na" (not applicable), the value "na" is treated as a special value for that syntax element or variable. The value "na" is considered not to be equal to any other value.

[0479] Bitwise operators The following bitwise operators are defined as follows: The bitwise "logical AND". When performing an operation on an integer argument, the operation is performed on the two's complement representation of the integer value. When performing an operation on a binary argument containing fewer bits than another argument, the shorter argument is expanded by adding higher bits equal to 0. | Bitwise "logical OR". When performing operations on integer arguments, the operation is performed on the two's complement representation of the integer value. When performing operations on binary arguments containing fewer bits than another argument, the shorter argument is expanded by adding higher bits equal to 0. ^ Bitwise "exclusive OR". When performing the operation on an integer argument, it operates on the two's complement representation of the integer value. When performing the operation on a binary argument containing fewer bits than another argument, the shorter argument is expanded by adding higher bits equal to 0. x >> y is an arithmetic right shift of only y digits in the two's complement integer representation of x. This function is defined only for non-negative integer values ​​of y. The bit shifted to 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: An arithmetic left shift of only y digits in the two's complement integer representation of x. This function is defined only for non-negative integer values ​​of y. The bit shifted to the least significant bit (LSB) as a result of the left shift has a value equal to 0.

[0480] Assignment Operator The following arithmetic operators are defined as follows: = Assignment operator. The increment operator ++, i.e., x++, is equivalent to x = x + 1 and, when used in array indices, evaluates to the value of the variable before the increment operation. -- Decrement, i.e., x -- is equivalent to x = x - 1, and when used in an array index, it evaluates to the value of the variable before the decrement operation. += increments by a specified amount; that is, x += 3 is equivalent to x = x + 3, and x += (-3) is equivalent to x = x + (-3). -= decrements by a specified amount; that is, x -= 3 is equivalent to x = x - 3, and x -= (-3) is equivalent to x = x - (-3).

[0481] Range notation The following notation is used to specify a range of values. x = y . . zx takes integer values ​​that include all values ​​from y to z, where x, y, and z are integers, and z is greater than y.

[0482] Mathematical functions The following mathematical functions are defined.

[0483]

number

[0484] Asin(x) is the trigonometric inverse sine function that operates on an argument x within the range of -1.0 to 1.0, and has an output value within the range of -π÷2 to π÷2 in radians. Atan(x) is the arctangent function of trigonometry, which is performed on the argument x and has an output value in radians that includes all values ​​from -π÷2 to π÷2.

[0485]

number

[0486] Ceil(x) The smallest integer greater than or equal to x. Clip1 Y ( x ) = Clip3( 0, ( 1 << BitDepth Y ) - 1, x ) Clip1 C ( x ) = Clip3( 0, ( 1 << BitDepth C ) - 1, x )

[0487]

number

[0488] Cos(x) is the trigonometric cosine function that operates on an argument x in radians. Floor(x): The largest integer less than or equal to x.

[0489]

number

[0490] Ln(x) is the natural logarithm of x (the logarithm with base e, where e is the base constant of the natural logarithm, 2.718 281 828...). Log2(x) is the logarithm of x with base 2. Log10(x) is the logarithm of x with base 10.

[0491]

number

[0492] Round( x ) = Sign( x ) * Floor( Abs( x ) + 0.5 )

[0493]

number

[0494] Sin(x) is the trigonometric sine function that operates on an argument x in radians.

[0495]

number

[0496] Swap(x, y) = (y, x) Tan(x) is the trigonometric tangent function that operates on an argument x in radians.

[0497] Order of operations When the order of precedence in an expression is not explicitly indicated by the use of parentheses, the following rules apply: - Higher-priority operations are evaluated before any lower-priority operations. - Operations with the same priority are evaluated sequentially from left to right.

[0498] The table below specifies the order of operations from highest to lowest, with higher positions in the table indicating higher priority.

[0499] With respect to those operators, which are also used in the C programming language, the order of precedence used in this specification is the same as that used in the C programming language.

[0500] [Table 89]

[0501] Description of logical operations In the text, statements of logical operations that will be mathematically described in the following format, namely, if (condition 0) Statement 0 else if (condition 1) Statement 1 ... else / * Explanatory notes for the remaining conditions * / statement n This can be explained in the following forms. ...The following applies / ... - If condition is 0, then statement 0 - Otherwise, if condition 1 is true, then statement 1 - ... - Otherwise (explanatory note in the remaining conditions), statement n

[0502] Each "if...then...if...otherwise..." statement in the text is introduced with "...if...then..." or "...the following applies," followed immediately by "...if...then...if...otherwise..." The final condition in "...if...then...if...otherwise..." is always "...otherwise..." Alternating "if...then...if...then...if...otherwise..." statements can be identified by aligning the "...as follows..." or "...the following applies" with the final "...otherwise..."

[0503] In the text, statements of logical operations that will be mathematically described in the following format, namely, if(condition 0a && condition 0b) Statement 0 else if(condition 1a || condition 1b) Statement 1 ... else statement n This can be explained in the following forms. ...The following applies / ... - If all of the following conditions are true, then statement 0: - 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

[0504] In the text, statements of logical operations that will be mathematically described in the following format, namely, if (condition 0) Statement 0 if (condition 1) Statement 1 This can be explained in the following forms. When condition 0, statement 0 When condition 1 is met, statement 1

[0505] While embodiments of the invention are primarily described in relation to video coding, it should be noted that embodiments of the coding system 10, encoder 20, and decoder 30 (and correspondingly system 10), and other embodiments described herein, may also be configured for still picture processing or coding, i.e., for processing or coding individual pictures independently of any preceding or consecutive pictures, as in video coding. Generally, when picture processing coding is limited to a single picture 17, only the interpretation units 244 (encoder) and 344 (decoder) may be available. All other functions (also called tools or techniques) of the video encoder 20 and video decoder 30 can be equally used for still picture processing, e.g., residual calculation 204 / 304, transformation 206, quantization 208, inverse quantization 210 / 310, (inverse) transformation 212 / 312, segmentation 262 / 362, intra prediction 254 / 354, and / or loop filtering 220, 320, and entropy coding 270 and entropy decoding 304.

[0506] For example, embodiments of the encoder 20 and decoder 30, and the functions described herein with reference to, for example, 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 as one or more instructions or codes in a computer-readable medium or transmitted over a communication medium and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium such as a data storage medium, or a communication medium including any medium that facilitates the transfer of computer programs from one place to another according to a communication protocol, for example. In this embodiment, the computer-readable medium may generally correspond to (1) a non-transient tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. The data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for the implementation of the techniques described herein. A computer program product may include a computer-readable medium.

[0507] For example, and without 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 appropriately called 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, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of a medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals, or other temporary media, but instead refer to non-temporary tangible storage media. The terms "disk" and "disc" as used herein include Compact Disc (CD), LaserDisc® (disc), Optical Disc (disc), Digital Multipurpose Disc (disc) (DVD), Floppy Disk (disk), and Blu-ray® Disc (disc), where a disk typically reproduces data magnetically, while a disc reproduces data optically using a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0508] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the term “processor” as used herein may refer to any of the above-described structures or any other structure suitable for implementing the techniques described herein. In addition, in some embodiments, the functions described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated within a combined codec. Furthermore, the techniques can be fully implemented within one or more circuits or logic elements.

[0509] The techniques of this disclosure can be implemented in a wide variety of devices or apparatus, including wireless handsets, integrated circuits (ICs), or sets of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to highlight the functional aspects of a device configured to perform the techniques disclosed, but do not necessarily require implementation by different hardware units. Rather, as described above, various units may be combined within a codec hardware unit, or provided with suitable software and / or firmware by a set of interoperable hardware units, including one or more processors as described above. [Explanation of Symbols]

[0510] 10 Video Coding Systems 12 Source Devices 13 Communication Channels 14 Destination device 16 Picture Sources 17. Pictures, picture data, unprocessed pictures, unprocessed picture data 18. Preprocessor, pre-processing unit 19 Pre-processed pictures, pre-processed picture data 20 Video Encoders 21 Encoded picture data 22 Communication interface, communication unit 28 Communication interface, communication unit 30 video decoders, short decoders 31 Decoded picture, decoded picture data 32 Post-processors, Post-processing Units 33 Post-processed pictures, post-processed picture data 34 Display Devices 46 Processing Circuit 201 Input, Input Interface 203 Picture Block 204 Residual Calculation Unit 205 Residual block, residual 206 Conversion Processing Unit 207 Conversion coefficient 208 Quantization Units 209 Quantized coefficients, quantization transformation coefficients, quantization residual coefficients 210 Inverse Quantization Unit 211 Dequantized coefficients, inverse quantized residual coefficients 212 Inverse Transform Processing Unit 213 Reconstructed residual block, corresponding dequantized coefficient, transform block 214 Reconfiguration Unit 215 Reconstructed Blocks 220 Loop Filter Unit 221 Filtered blocks, filtered and reconfigured blocks 230 Decoded picture buffer 231 Decoded picture 244 Interpretation Units 254 Intra Prediction Units 260 Mode Selection Unit 262 division units 265 prediction blocks, predictors 266 Syntax Elements 270 Entropy Encoder Units 272 outputs, output interface 304 Entropy Decode Unit 309 Quantized coefficients 310 Inverse Quantization Unit 311 Transformation coefficients, dequantized coefficients 312 Inverse Transform Processing Unit 313 Reconstructed residual blocks, transformed blocks 314 Reconfiguration Unit, Adder 315 Reconstructed Blocks 320 Loop Filter Unit 321 Filtered blocks, decoded video blocks of pictures 330 Decoded Picture Buffer (DPB) 331 Decoded picture 332 output 344 Interpretation Units 354 Intra Prediction Units 360 Mode Applicable Unit 365 Prediction Block 400 video coding devices 410 Inlet port, Input port 420 Receiver Unit 430 processors, logical units, central processing unit 440 Transmitter Unit 450 exit ports, output ports 460 memory 470 coding modules 500 devices 502 Processors 504 memory 506 Codes and Data 508 Operating Systems 510 Application Programs 512 Bus 514 Secondary Storage 518 displays 1400 Decode Devices 1401 Receiver Module 1402 Parameter Processing Module 1403 Mapping Module 1404 Prediction Module 3100 Content Supply System 3102 Capture Device 3104 Communication Link 3106 Terminal device 3108 Smartphone / Pad 3110 Computer / Laptop 3112 Network Video Recorder / Digital Video Recorder 3114 TV 3116 Set-Top Box 3118 Video conferencing system 3120 Video Surveillance System 3122 Mobile Information Terminal 3124 Vehicle-mounted devices 3126 Display 3202 Protocol Progress Unit 3204 Demultiplexing Unit 3206 Video Decoder 3208 Audio Decoder 3210 Subtitle Decoder 3212 Synchronization Unit 3214 Video / Audio Display 3216 Video / Audio / Subtitle Display

Claims

1. A coding method performed by a decoding device, Steps to obtain the video bitstream, The steps include decoding the video bitstream to obtain the value of the chroma format display information for the current coding block, The steps include obtaining an initial intra-prediction mode value for the chroma component of the current coding block, When the value of the chroma format display information for the current coding block is equal to the default value, the steps include obtaining the mapped intra-prediction mode value for the chroma component of the current coding block according to the default mapping relationship and the initial intra-prediction mode value, A step of obtaining predicted sample values ​​for the chroma component of the current coding block according to the mapped intra-predicted mode value. A method for providing this.

2. The method according to claim 1, wherein the default value is 2 or 1, the default value being 2 represents a chroma format of 4:2:2, and the default value being 1 represents a chroma format of 4:2:

0.

3. The method according to claim 1 or 2, wherein the initial intra-prediction mode value for the chroma component of the current coding block is obtained based on the intra-prediction mode for the luma component of the current coding block.

4. The following table represents the aforementioned default mapping relationships, namely, Table 1 or Table 2 The method according to any one of claims 1 to 3, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

5. The following table represents the aforementioned default mapping relationships, namely, Table 3 The method according to any one of claims 1 to 4, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

6. The following table represents the aforementioned default mapping relationships, namely, Table 4 The method according to any one of claims 1 to 5, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

7. The following table represents the aforementioned default mapping relationships, namely, Table 5 The method according to any one of claims 1 to 6, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

8. The following table represents the aforementioned default mapping relationships, namely, Table 6 The method according to any one of claims 1 to 3, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

9. A decoder (30) comprising a processing circuit for performing the method described in any one of claims 1 to 8.

10. A coding method performed by an encoding device, The steps include obtaining the initial intra-prediction mode value for the current coding block, The steps include determining whether the ratio between the width of the current coding block relative to the rumor component and the width of the current coding block relative to the chroma component is equal to a threshold, When the ratio between the width of the lumen component of the current coding block and the width of the chroma component of the current coding block is equal to the threshold value, the steps include obtaining a mapped intra-predictive mode value for the chroma component of the current coding block according to a default mapping relationship and the initial intra-predictive mode value, The steps include coding the current coding block according to the mapped intra-predicted mode value and A method for providing this.

11. The method described above is The method according to claim 10, further comprising the step of encoding a value of chroma format display information for the current coding block into a bitstream, wherein the value of the chroma format display information represents the ratio between the width of the rumor component of the current coding block and the width of the chroma component of the current coding block.

12. The following table represents the aforementioned default mapping relationships, namely, Table 7 or Table 8 The method according to claim 10 or 11, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

13. The following table represents the aforementioned default mapping relationships, namely, Table 9 The method according to claim 10 or 11, wherein a is used, and mode X represents the initial intra-predicted mode value, and mode Y represents the mapped intra-predicted mode value.

14. A computer program product comprising program code for performing the method described in any one of claims 1 to 8 and 10 to 13.

15. It is a decoder, One or more processors, A decoder comprising a non-temporary computer-readable storage medium coupled to the processor and storing a program for execution by the processor, wherein the decoder is configured to perform the method according to any one of claims 1 to 8 when the program is executed by the processor.

16. It is an encoder, One or more processors, An encoder comprising a non-temporary computer-readable storage medium coupled to the processor and storing a program for execution by the processor, wherein the encoder is configured to perform the method according to any one of claims 10 to 13 when the program is executed by the processor.

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