Method and apparatus for predictive candidate list size signaling for intra picture block compensation

Abstract

To provide a video coding method and an apparatus for a predictive candidate list size signaling for intra picture block compensation.SOLUTION: A video decoding method includes the steps of: receiving a coded video bitstream including a current picture; determining a predetermined condition associated with signaling data included in the coded video bitstream; determining size of an index included in the signaling data for a candidate list of vector prediction based on the number of merge mode candidates and the number of intra block copy (IBC) candidates based on the predetermined condition; creating a candidate list using the vector prediction; retrieving the vector prediction from the candidate list according to the index having a value not exceeding the determined size of the index; and decoding the current block according to the retrieved vector prediction.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] Incorporation by Reference This disclosure claims the benefit of priority to U.S. Patent Application No. 16 / 863,661, entitled "Method and Apparatus for Prediction Candidate List Size Signaling for Intra-Picture Block Compensation," filed April 30, 2020, which in turn claims the benefit of priority to U.S. Provisional Application No. 62 / 904,307, entitled "Prediction Method for Intra-Picture Block Compensation," filed September 23, 2019, and U.S. Provisional Application No. 62 / 873,044, entitled "Prediction Candidate List Size Signaling for Intra-Picture Block Compensation," filed July 11, 2019. The entire disclosures of the prior applications are incorporated herein by reference in their entireties.

[0002] This disclosure describes embodiments that relate generally to video coding. [Background technology]

[0003] The background art description provided herein is intended to generally present the context of the present disclosure. The work of the currently named inventors, to the extent that it is described in this background art section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure.

[0004] Video coding and decoding may be performed using inter-picture prediction with motion compensation. Uncompressed digital video may include a sequence of pictures, each having spatial dimensions of, for example, 1920x1080 luminance samples and associated chrominance samples. The sequence of pictures may have a fixed or variable picture rate (also informally known as frame rate), for example, 60 pictures per second or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 luminance sample resolution at 60 Hz frame rate) with 8 bits per sample requires a bandwidth approaching 1.5 Gbits / s. One hour of such video requires more than 600 Gbytes of storage space.

[0005] One of the goals of video coding and decoding is to be able to reduce redundancy in the input video signal through compression. Compression can help reduce the aforementioned bandwidth or storage space requirements, in some cases by more than two orders of magnitude. Both lossless and lossy compression, as well as combinations thereof, can be employed. Lossless compression refers to techniques that can reconstruct an exact copy of the original signal from the compressed original signal. When using lossy compression, the reconstructed signal may not be identical to the original signal, but the distortion between the original and reconstructed signal is small enough that the reconstructed signal becomes useful in the intended application. For video, lossy compression is widely adopted. The amount of acceptable distortion varies from application to application, for example, users of certain consumer streaming applications may tolerate higher distortion than users of television distribution applications. The achievable compression ratio may reflect that the more tolerable / acceptable distortion, the higher the compression ratio may be.

[0006] Motion compensation can be a lossy compression technique, and can refer to a technique in which blocks of sample data from a previously reconstructed picture or part thereof (reference picture) are used to predict a newly reconstructed picture or picture part after being spatially shifted in a direction indicated by a motion vector (hereafter MV). In some cases, the reference picture can be the same as the picture currently being reconstructed. The MV can have two dimensions X and Y, or three dimensions, the third of which can be an indication of the reference picture in use (the latter can indirectly be a temporal dimension).

[0007] In some video compression techniques, the MV applicable to a region of sample data may be predicted from other MVs, e.g., from one associated with another region of sample data that is spatially adjacent to the region being reconstructed and precedes that MV in decoding order. Doing so may significantly reduce the amount of data required to code the MV, thereby eliminating redundancy and increasing compression. MV prediction may work effectively, for example, when coding an input video signal derived from a camera (known as natural video), because there is a statistical likelihood that regions larger than the region to which a single MV is applicable will move in similar directions and therefore, in some cases, may be predicted using similar motion vectors derived from MVs of nearby regions. This allows the MV found for a given region to be similar or the same as the MV predicted from the surrounding MVs, and after entropy coding, may be represented with fewer bits than would be used when coding the MV directly. In some cases, MV prediction may be an example of lossless compression of a signal (i.e., MV) derived from the original signal (i.e., sample stream). In other cases, the MV prediction itself may be lossy, for example, due to rounding errors when computing a predictor from several surrounding MVs.

[0008] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T Rec. H.265, "High Efficiency Video Coding", December 2016). Here, we describe one of the many MV prediction mechanisms provided by H.265, hereafter referred to as "spatial merging".

[0009] Referring to FIG. 1, a current block (101) contains samples found by the encoder during a motion search process as predictable from a previous block of the same size, spatially shifted. Instead of coding its MV directly, the MV can be derived from metadata associated with one or more reference pictures, for example from the most recent reference picture (in decoding order), using MVs associated with any one of five surrounding samples, denoted A0, A1, and B0, B1, B2 (102 to 106, respectively). In H.265, MV prediction can use a predictor from the same reference picture that neighboring blocks use. The order of forming the candidate list may be A0→B0→B1→A1→B2. Summary of the Invention [Means for solving the problem]

[0010] According to an exemplary embodiment, a method of video decoding includes receiving a coded video bitstream including a current picture. The method includes determining a predetermined condition associated with signaling data included in the coded video bitstream. The method includes determining a size of an index included in the signaling data for a candidate list of a vector predictor based on the predetermined condition and based on a number of merge mode candidates and a number of intra block copy (IBC) candidates. The method includes creating a candidate list using the vector predictor. The method includes retrieving a vector predictor from the candidate list according to an index having a value not exceeding the determined size of the index. The method further includes decoding the current block according to the retrieved vector predictor.

[0011] According to an example embodiment, a method of video decoding includes receiving a coded video bitstream including a current picture. The method further includes retrieving signaling data from the coded video bitstream for a current block. The method further includes determining whether a maximum number of merging candidates is included in the retrieved signaling data for the current block. The method further includes setting a maximum number of intra block copy (IBC) candidates based on a determination of whether the maximum number of merging candidates is included in the signaling data for the current block.

[0012] According to an exemplary embodiment, a video decoding device for video decoding includes a processing circuit configured to receive a coded video bitstream including a current picture. The processing circuit is further configured to determine a predetermined condition associated with signaling data included in the coded video bitstream. The processing circuit is further configured to determine a size of an index included in the signaling data for a candidate list of vector prediction based on the predetermined condition and based on a number of merge mode candidates and a number of intra block copy (IBC) candidates. The processing circuit is further configured to create a candidate list using the vector prediction and retrieve the vector prediction from the candidate list according to an index having a value not exceeding the determined size of the index. The processing circuit is further configured to decode the current block according to the retrieved vector prediction.

[0013] According to an example embodiment, a video decoder apparatus for video decoding includes a processing circuit configured to receive a coded video bitstream including a current picture. The processing circuit is further configured to retrieve signaling data from the coded video bitstream for a current block. The processing circuit is further configured to determine whether a maximum number of merging candidates is included in the retrieved signaling data for the current block. The processing circuit is further configured to set a maximum number of intra block copy (IBC) candidates based on a determination of whether the maximum number of merging candidates is included in the signaling data for the current block.

[0014] A non-transitory computer-readable medium having instructions stored thereon, which when executed by a processor of a video decoder, cause the processor to perform a method comprising receiving a coded video bitstream including a current picture. The method comprises determining a predetermined condition associated with signaling data included in the coded video bitstream. The method comprises determining a size of an index included in the signaling data for a candidate list of vector prediction based on the predetermined condition and based on a number of merge mode candidates and a number of intra block copy (IBC) candidates. The method comprises creating a candidate list using the vector prediction. The method comprises retrieving a vector prediction from the candidate list according to an index having a value not exceeding the determined size of the index. The method further comprises decoding the current block with the retrieved vector prediction.

[0015] A non-transitory computer-readable medium having instructions stored thereon that, when executed by a processor of a video decoder, cause the processor to perform a method comprising receiving a coded video bitstream including a current picture. The method further comprises extracting signaling data from the coded video bitstream for a current block. The method further comprises determining whether a maximum number of merging candidates is included in the extracted signaling data for the current block. The method further comprises setting a maximum number of intra block copy (IBC) candidates based on a determination of whether the maximum number of merging candidates is included in the signaling data for the current block.

[0016] Further features, nature and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1]FIG. 2 is a schematic diagram of a current block and its surrounding spatial merge candidates in one example. [Diagram 2] FIG. 2 is a schematic diagram of a simplified block diagram of a communication system (200) according to one embodiment. [Diagram 3] FIG. 3 is a schematic diagram of a simplified block diagram of a communication system (300) according to one embodiment. [Figure 4] FIG. 2 is a schematic diagram of a simplified block diagram of a decoder according to one embodiment. [Diagram 5] FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment. [Figure 6] FIG. 4 is a block diagram of an encoder according to another embodiment. [Figure 7] FIG. 4 is a block diagram of a decoder according to another embodiment. [Figure 8] FIG. 2 is a schematic diagram of intra-picture block compensation according to one embodiment; [Figure 9A] FIG. 2 is a schematic diagram of intra-picture block compensation using a search range of one coding tree unit (CTU) size according to one embodiment. [Figure 9B] FIG. 2 is a schematic diagram of intra-picture block compensation using a search range of one coding tree unit (CTU) size according to one embodiment. [Figure 9C] FIG. 2 is a schematic diagram of intra-picture block compensation using a search range of one coding tree unit (CTU) size according to one embodiment. [Figure 9D] FIG. 2 is a schematic diagram of intra-picture block compensation using a search range of one coding tree unit (CTU) size according to one embodiment. [Figure 10A] FIG. 2 is a schematic diagram of how a buffer is updated according to an embodiment. [Figure 10B] FIG. 2 is a schematic diagram of how a buffer is updated according to an embodiment. [Figure 10C] FIG. 2 is a schematic diagram of how a buffer is updated according to an embodiment. [Figure 10D]FIG. 2 is a schematic diagram of how a buffer is updated according to an embodiment. [Figure 11A] FIG. 1 is a diagram of a decoding flow chart for a history-based MV prediction (HMVP) buffer. [Figure 11B] FIG. 13 is a schematic diagram of updating the HMVP buffer. [Figure 12] FIG. 2 is a diagram of an exemplary decoding process according to one embodiment. [Figure 13] FIG. 2 is a diagram of an exemplary decoding process according to one embodiment. [Figure 14] FIG. 1 is a schematic diagram of a computer system according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] FIG. 2 illustrates a simplified block diagram of a communication system (200) according to one embodiment of the present disclosure. The communication system (200) includes a plurality of terminal devices capable of communicating with each other, for example, via a network (250). For example, the communication system (200) includes a first pair of terminal devices (210) and (220) interconnected via the network (250). In the example of FIG. 2, the first pair of terminal devices (210) and (220) perform unidirectional transmission of data. For example, the terminal device (210) can encode video data (e.g., a stream of video pictures captured by the terminal device (210)) for transmission to another terminal device (220) via the network (250). The coded video data can be transmitted in the form of one or more coded video bitstreams. The terminal device (220) can receive the coded video data from the network (250), decode the coded video data to reconstruct the video pictures, and display the video pictures using the reconstructed video data. Unidirectional data transmission may be common, such as in media serving applications.

[0019] In another example, the communication system (200) includes a second pair of terminal devices (230) and (240) performing bidirectional transmission of coded video data, such as may occur during a video conference. For the bidirectional transmission of data, in one example, each of the terminal devices (230) and (240) can encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission to the other of the terminal devices (230) and (240) over the network (250). Each of the terminal devices (230) and (240) can also receive coded video data transmitted by the other of the terminal devices (230) and (240), decode the coded video data to recover the video pictures, and display the video pictures on a display device accessible via the recovered video data.

[0020] In the example of FIG. 2, the terminals (210), (220), (230), and (240) may be depicted as a server, a personal computer, and a smartphone, although the principles of the present disclosure may not be so limited. It is understood that embodiments of the present disclosure find use with laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. The network (250) represents any number of networks that convey coded video data between the terminals (210), (220), (230), and (240), including, for example, wired (wired) and / or wireless communication networks. The communication network (250) may exchange data over circuit-switched and / or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this discussion, the architecture and topology of the network (250) may not be important to the operation of the present disclosure unless otherwise described herein below.

[0021] 3 illustrates the arrangement of a video encoder and a video decoder in a streaming environment as an example of an application of the disclosed subject matter. The disclosed subject matter may be equally applied to other video-enabled applications including, for example, video conferencing, digital TV, storage of compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0022] The streaming system may include a video source (301), e.g., a digital camera, and may include a capture subsystem (313) that creates a stream of video pictures (302), e.g., uncompressed. In one example, the stream of video pictures (302) includes samples taken by the digital camera. The stream of video pictures (302), shown as a thick line to emphasize the high amount of data compared to the coded video data (304) (or coded video bitstream), may be processed by an electronic device (320) that includes a video encoder (303) coupled to the video source (301). The video encoder (303) may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The coded video data (304) (or coded video bitstream (304)), shown as a thin line to emphasize the lower amount of data when compared to the stream of video pictures (302), may be stored in a streaming server (305) for future use. One or more streaming client subsystems, such as the client subsystems (306) and (308) of FIG. 3, can access the streaming server (305) to retrieve copies (307) and (309) of the coded video data (304). The client subsystem (306) can include, for example, a video decoder (310) of an electronic device (330). The video decoder (310) decodes an input copy (307) of the coded video data and creates an output stream (311) of video pictures that can be rendered on a display (312) (e.g., a display screen) or other rendering device (not shown). In some streaming systems, the coded video data (304), (307), and (309) (e.g., a video bitstream) can be encoded according to a particular video coding / compression standard. Examples of such standards include ITU-T Recommendation H.265.For example, a video coding standard under development is informally known as Versatile Video Coding (VVC), and the disclosed subject matter may be used in the context of VVC.

[0023] It should be noted that the electronic devices (320) and (330) may include other components (not shown). For example, the electronic device (320) may include a video decoder (not shown), and the electronic device (330) may also include a video encoder (not shown).

[0024] 4 shows a block diagram of a video decoder (410) according to one embodiment of the present disclosure. The video decoder (410) may be included in an electronic device (430). The electronic device (430) may include a receiver (431) (e.g., a receiving circuit). The video decoder (410) may be used in place of the video decoder (310) of the example of FIG. 3.

[0025] The receiver (431) can receive one or more coded video sequences to be decoded by the video decoder (410), in the same or another embodiment, one coded video sequence at a time, with the decoding of each coded video sequence being independent of the other coded video sequences. The coded video sequences can be received from a channel (401), which can be a hardware / software link to a storage device that stores the coded video data. The receiver (431) can receive the coded video data along with other data, e.g., coded audio data and / or auxiliary data streams, which can be forwarded to a respective usage entity (not shown). The receiver (431) can separate the coded video sequences from the other data. To combat network jitter, a buffer memory (415) can be coupled between the receiver (431) and the entropy decoder / parser (420) (hereinafter, "parser (420)"). In certain applications, the buffer memory (415) is part of the video decoder (410). In other cases, it may be external to the video decoder (410) (not shown). In still other cases, there may be a buffer memory (not shown) external to the video decoder (410), for example to suppress network jitter, and another buffer memory (415) internal to the video decoder (410), for example to handle playback timing. When the receiver (431) is receiving data from a store / forward device of sufficient bandwidth and controllability, or from an equally synchronous network, the buffer memory (415) may not be needed or may be small. For use with best-effort packet networks such as the Internet, the buffer memory (415) may be needed and may be relatively large, advantageously of adaptive size, and may be implemented at least in part in an operating system or similar element (not shown) external to the video decoder (410).

[0026] The video decoder (410) may include a parser (420) for reconstructing symbols (421) from the coded video sequence. The categories of symbols include information used to manage the operation of the video decoder (410) and potentially information for controlling a rendering device such as a rendering device (412) (e.g., a display screen) that is not an integral part of the electronic device (430) but may be coupled to the electronic device (430) as shown in FIG. 4. The rendering device control information may be in the form of a supplemental enhancement information (SEI message) or a video usability information (VUI) parameter set fragment (not shown). The parser (420) may parse / entropy decode the received coded video sequence. The coding of the coded video sequence may be according to a video coding technique or standard and may follow various principles including variable length coding, Huffman coding, arithmetic coding with or without context-dependent, etc. The parser (420) may extract at least one set of subgroup parameters for a subgroup of pixels of the video decoder from the coded video sequence based on at least one parameter corresponding to the group. The subgroups may include groups of pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The parser (420) can also extract from the coded video sequence information such as transform coefficients, quantization parameter values, motion vectors, etc.

[0027] The parser (420) can perform entropy decoding / parsing operations on the video sequence received from the buffer memory (415) to create symbols (421).

[0028] The reconstruction of the symbols (421) may involve a number of different units, depending on the type of coded video picture or part thereof (e.g., inter-picture and intra-picture, inter-block and intra-block), and other factors. Which units are involved and how may be controlled by subgroup control information parsed from the coded video sequence by the parser (420). The flow of such subgroup control information between the parser (420) and the following units is not shown for clarity.

[0029] Beyond the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these units may interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, the following conceptual subdivision into functional units is appropriate.

[0030] The first unit is a scaler / inverse transform unit (451), which receives quantized transform coefficients as well as control information from the parser (420) including the transform to use, block size, quantization coefficients, quantization scaling matrix, etc. as symbols (421). The scaler / inverse transform unit (451) can output blocks containing sample values ​​that can be input to an aggregator (455).

[0031] In some cases, the output samples of the scaler / inverse transform (451) may relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture, but can use prediction information from a previously reconstructed portion of the current picture. Such prediction information may be provided by an intra-picture prediction unit (452). In some cases, the intra-picture prediction unit (452) generates a block of the same size and shape as the block being reconstructed using surrounding already reconstructed information fetched from a current picture buffer (458). The current picture buffer (458) buffers, for example, a partially reconstructed current picture and / or a fully reconstructed current picture. The aggregator (455) adds, possibly on a sample-by-sample basis, the prediction information generated by the intra-prediction unit (452) to the output sample information provided by the scaler / inverse transform unit (451).

[0032] In other cases, the output samples of the scaler / inverse transform unit (451) may relate to an inter-coded, potentially motion-compensated block. In such cases, the motion compensated prediction unit (453) may access the reference picture memory (457) to fetch samples used for prediction. After motion compensating the samples fetched with the symbols (421) associated with the block, these samples may be added to the output of the scaler / inverse transform unit (451) by the aggregator (455) (in this case referred to as residual samples or residual signals) to generate output sample information. The addresses in the reference picture memory (457) from which the motion compensated prediction unit (453) fetches the prediction samples may be controlled by motion vectors, available to the motion compensated prediction unit (453), for example in the form of symbols (421), which may have X, Y, and reference picture components. Motion compensation may also include interpolation of sample values ​​fetched from the reference picture memory (457) when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, and the like.

[0033] The output samples of the aggregator (455) may depend on various loop filtering techniques in the loop filter unit (456). Video compression techniques may include in-loop filter techniques controlled by parameters contained in the coded video sequence (also called coded video bitstream) and made available to the loop filter unit (456) as symbols (421) from the parser (420), but may also be responsive to meta-information obtained during decoding of a previous (in decoding order) part of the coded picture or coded video sequence, as well as to previously reconstructed and loop filtered sample values.

[0034] The output of the loop filter unit (456) may be a sample stream that may be output to a rendering device (412) and also stored in a reference picture memory (457) for use in future inter-picture prediction.

[0035] Once a particular coded picture is fully reconstructed, it can be used as a reference picture for future prediction. For example, once a coded picture corresponding to a current picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by the parser (420)), the current picture buffer (458) can become part of the reference picture memory (457), and a new current picture buffer can be reallocated before beginning reconstruction of the next coded picture.

[0036] The video decoder (410) may perform decoding operations according to a given video compression technique of a standard, such as ITU-T Rec. H.265. The coded video sequence may comply with the syntax specified in the video compression technique or standard being used, in the sense that the coded video sequence complies with both the syntax and the profile of the video compression technique or standard, as documented in the video compression technique or standard. Specifically, the profile may select a particular tool from all tools available in the video compression technique or standard as the only tool available under that profile. Also, what is required for compliance may be that the complexity of the coded video sequence is within a range defined by the level of the video compression technique or standard. In some cases, the level limits the maximum picture size, maximum frame rate, maximum reconstruction sample rate (e.g., measured in megasamples per second), maximum reference picture size, etc. The limits set by the level may be further limited in some cases by the specification of a hypothetical reference decoder (HRD) and metadata for HRD buffer management signaled in the coded video sequence.

[0037] In one embodiment, the receiver (431) can receive additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0038] 5 shows a block diagram of a video encoder (503) according to one embodiment of the present disclosure. The video encoder (503) is included in an electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) may be used in place of the example video encoder (303) of FIG.

[0039] The video encoder (503) can receive video samples from a video source (501) (which in the example of FIG. 5 is not part of the electronic device (520)) that can capture video images to be encoded by the video encoder (503). In another example, the video source (501) is part of the electronic device (520).

[0040] The video source (501) may provide a source video sequence to be encoded by the video encoder (503) in the form of a digital video sample stream that may be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, ...), and from any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the video source (501) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (501) may be a camera that captures local image information as a video sequence. The video data may be provided as multiple individual pictures that give motion when viewed in sequence. The pictures themselves may be organized as a spatial array of pixels, each of which may contain one or more samples, depending on the sampling structure, color space, etc., in use. Those skilled in the art may easily understand the relationship between pixels and samples. The following description focuses on samples.

[0041] According to one embodiment, the video encoder (503) can encode and compress pictures of a source video sequence into a coded video sequence (543) in real-time or under any other time constraint required by an application. Enforcing an appropriate coding rate is one function of the controller (550). In some embodiments, the controller (550) controls and is operatively coupled to other functional units as described below. For clarity, couplings are not shown. Parameters set by the controller (550) may include rate control related parameters (picture skip, quantizer, lambda value for rate distortion optimization techniques, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (550) may be configured with other appropriate functions for the video encoder (503) optimized for a particular system design.

[0042] In some embodiments, the video encoder (503) is configured to operate in a coding loop. As an oversimplified explanation, in one example, the coding loop can include a source coder (530) (e.g., responsible for generating symbols, such as a symbol stream, based on an input picture to be coded and a reference picture) and a (local) decoder (533) built into the video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a similar manner that the (remote) decoder also does (since in the video compression techniques contemplated in the disclosed subject matter, any compression between the symbols and the coded video bitstream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (534). The decoding of the symbol stream produces a bit-accurate result regardless of the location of the decoder (local or remote), so the contents of the reference picture memory (534) are also bit-accurate between the local and remote encoders. In other words, the prediction part of the encoder "sees" exactly the same sample values ​​as the reference picture samples that the decoder "sees" when using the prediction during decoding. This basic principle of reference picture synchrony (and the drift that occurs when synchrony cannot be maintained, e.g., due to channel errors) is also used in several related technologies.

[0043] The operation of the "local" decoder (533) may be the same as that of a "remote" decoder, such as the video decoder (410), which has already been described in detail above in connection with Figure 4. However, with brief reference also to Figure 4, because symbols are available and the encoding / decoding of symbols into a coded video sequence by the entropy coder (545) and parser (420) may be lossless, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and parser (420), may not be fully implemented in the local decoder (533).

[0044] An observation that can be made at this point is that decoder techniques other than analysis / entropy decoding present in a decoder must necessarily be present in the corresponding encoder in substantially identical functional form. For this reason, the disclosed subject matter focuses on the decoder operation. A description of the encoder techniques may be omitted, since they are the inverse of the decoder techniques described generically. Only in certain areas is a more detailed description necessary, which is provided below.

[0045] In operation, in some examples, the source coder (530) may perform motion-compensated predictive coding, which predictively codes an input picture with reference to one or more previously coded pictures from a video sequence designated as “reference pictures.” In this manner, the coding engine (532) codes differences between pixel blocks of the input picture and pixel blocks of reference pictures that may be selected as predictive references for the input picture.

[0046] The local video decoder (533) may decode the coded video data of pictures that may be designated as reference pictures based on the symbols created by the source coder (530). The operation of the coding engine (532) may advantageously be a lossy process. When the coded video data may be decoded in a video decoder (not shown in FIG. 5), the reconstructed video sequence may be a replica of the source video sequence, usually with some errors. The local video decoder (533) may replicate the decoding process that may be performed by the video decoder on the reference pictures and cause the reconstructed reference pictures to be stored in a reference picture cache (534). In this way, the video encoder (503) may locally store copies of reconstructed reference pictures that have common content as reconstructed reference pictures (without transmission errors) obtained by the far-end video decoder.

[0047] The prediction (535) may perform a predictive search of the coding engine (532). That is, for a new picture to be coded, the prediction (535) may retrieve the reference picture memory (534) and look for sample data (as candidate reference pixel blocks) or specific metadata, such as reference picture motion vectors, block shapes, etc., that may serve as suitable prediction references for the new picture. The prediction (535) may operate on sample blocks for each pixel block to find a suitable prediction reference. In some cases, as determined by the search results obtained by the prediction (535), the input picture may have prediction references drawn from multiple reference pictures stored in the reference picture memory (534).

[0048] The controller (550) can manage the coding operations of the source coder (530), including, for example, setting the parameters and subgroup parameters used to encode the video data.

[0049] The output of all the aforementioned functional units may undergo entropy coding in an entropy coder (545), which converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols via techniques such as Huffman coding, variable length coding, and arithmetic coding.

[0050] The transmitter (540) can buffer the coded video sequence created by the entropy coder (545) and prepare it for transmission over a communication channel (560), which can be a hardware / software link to a storage device that stores the coded video data. The transmitter (540) can merge the coded video data from the video coder (503) with other data to be transmitted, such as coded audio data and / or auxiliary data streams (sources not shown).

[0051] The controller (550) may manage the operation of the video encoder (503). During coding, the controller (550) may assign a particular coded picture type to each coded picture, which may affect the coding technique that may be applied to the respective picture. For example, pictures may often be assigned as any of the following picture types:

[0052] An intra picture (I-picture) may be one that can be coded and decoded without using any other picture of the sequence as a source of prediction. Some video codecs may use different types of intra pictures, such as, for example, independent decoder refresh ("IDR") pictures. Those skilled in the art are aware of these variations of I-pictures and their respective uses and characteristics.

[0053] A predictive picture (P picture) may be one that can be encoded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict sample values ​​for each block.

[0054] A bidirectionally predicted picture (B-picture) may be one that can be encoded and decoded using intra- or inter-prediction that uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, a multi-prediction picture may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0055] A source picture is usually spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks as determined by the coding assignment applied to the respective picture of the block. For example, blocks of an I picture may be non-predictively coded or they may be predictively coded with reference to already coded blocks of the same picture (spatial prediction or intra prediction). Pixel blocks of a P picture may be predictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. Pixel blocks of a B picture may be predictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

[0056] The video encoder (503) may perform coding operations in accordance with a given video coding technique or standard, such as ITU-T Rec. H.265. In its operations, the video encoder (503) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in the input video sequence. Thus, the coded video data may conform to a syntax specified by the video coding technique or standard being used.

[0057] In one embodiment, the transmitter (540) can transmit additional data along with the encoded video. The source coder (530) may include such data as part of the coded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0058] A video may be captured as multiple source pictures (video pictures) in a time sequence. Intra-picture prediction (often abbreviated as intra-prediction) exploits spatial correlation in a given picture, while inter-picture prediction exploits inter-picture (temporal or other) correlation. In one example, a particular picture being coded / decoded, called a current picture, is divided into blocks. When a block of the current picture resembles a reference block of a previously coded and still buffered reference picture of the video, the block of the current picture may be coded by a vector called a motion vector. A motion vector points to a reference block of a reference picture, and may have a third dimension that identifies the reference picture if multiple reference pictures are used.

[0059] In some embodiments, a bi-prediction technique may be used for inter-picture prediction. According to the bi-prediction technique, two reference pictures, such as a first reference picture and a second reference picture, are used, both of which are before the decoding order of the current picture of the video (but may be past and future, respectively, in the display order). A block of the current picture may be coded by a first motion vector that points to a first reference block of the first reference picture and a second motion vector that points to a second reference block of the second reference picture. A block may be predicted by a combination of the first reference block and the second reference block.

[0060] Furthermore, to improve coding efficiency, merge mode techniques can be used for inter-picture prediction.

[0061] According to some embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed on a block-by-block basis. For example, according to the HEVC standard, pictures of a sequence of video pictures are divided into coding tree units (CTUs) for compression, and the CTUs of a picture have the same size, such as 64x64 pixels, 32x32 pixels, or 16x16 pixels. In general, a CTU includes three coding tree blocks (CTBs), one luma CTB and two chroma CTBs. Each CTU can be recursively quad-tree partitioned into one or more coding units (CUs). For example, a CTU of 64x64 pixels may be partitioned into one CU of 64x64 pixels, or four CUs of 32x32 pixels, or 16 CUs of 16x16 pixels. In one example, each CU is analyzed to determine the prediction type of the CU, such as an inter-prediction type or an intra-prediction type. The CU is partitioned into one or more prediction units (PUs) depending on the temporal and / or spatial predictability. In general, each PU includes a luma prediction block (PB) and two chroma PBs. In one embodiment, the prediction operation in coding (encoding / decoding) is performed in units of prediction blocks. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values ​​(e.g., luma values) of 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, etc.

[0062] 6 shows a diagram of a video encoder (603) according to another embodiment of the present disclosure. The video encoder (603) is configured to receive a processed block of sample values ​​(e.g., a predictive block) in a current video picture of a sequence of video pictures and to encode the processed block into an encoded picture that is part of a coded video sequence. In one example, the video encoder (603) is used in place of the video encoder (303) of the example of FIG. 3.

[0063] In an HEVC example, the video encoder (603) receives a matrix of sample values ​​for a processing block, such as a predictive block of 8×8 samples. The video encoder (603) determines whether the processing block is best coded using intra mode, inter mode, or bi-predictive mode, for example using rate-distortion optimization. If the processing block is encoded in intra mode, the video encoder (603) may use intra prediction techniques to code the processing block into a coded picture, and when the processing block is to be encoded in inter mode or bi-predictive mode, the video encoder (603) may use inter prediction or bi-predictive techniques, respectively, to code the processing block into a coded picture. In certain video coding techniques, the merge mode may be an inter-picture prediction sub-mode in which a motion vector is derived from one or more motion vector predictions without the benefit of coded motion vector components outside the prediction. In certain other video coding techniques, there may be motion vector components applicable to the current block. In one example, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining the mode of the processing block.

[0064] In the example of FIG. 6, the video encoder (603) includes an inter-encoder (630), an intra-encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a general controller (621), and an entropy encoder (625), which are coupled together as shown in FIG.

[0065] The inter-encoder (630) is configured to receive a sample of a current block (e.g., a processing block), compare the block to one or more reference blocks of a reference picture (e.g., blocks of a previous picture and a subsequent picture), generate inter-prediction information (e.g., a description of redundant information by inter-coding techniques, motion vectors, merge mode information), and calculate an inter-prediction result (e.g., a predicted block) based on the inter-prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture that is decoded based on the encoded video information.

[0066] The intra encoder (622) is configured to receive samples of a current block (e.g., a processing block), possibly compare the block with blocks already encoded in the same picture, generate quantized coefficients after transformation, and possibly also generate intra prediction information (e.g., intra prediction direction information according to one or more intra encoding techniques). In one example, the intra encoder (622) also calculates an intra prediction result (e.g., a predicted block) based on the intra prediction information and a reference block of the same picture.

[0067] The general controller (621) is configured to determine general control data and control other components of the video encoder (603) based on the general control data. In one example, the general controller (621) determines a mode of the block and provides a control signal to the switch (626) based on the mode. For example, if the mode is an intra mode, the general controller (621) controls the switch (626) to select an intra mode result to be used by the residual calculator (623) and controls the entropy encoder (625) to select intra prediction information and include the intra prediction information in the bitstream, and if the mode is an inter mode, the general controller (621) controls the switch (626) to select an inter prediction result to be used by the residual calculator (623) and controls the entropy encoder (625) to select inter prediction information and include the inter prediction information in the bitstream.

[0068] The residual calculation unit (623) is configured to calculate a difference (residual data) between the received block and a prediction result selected from the intra-encoder (622) or the inter-encoder (630). The residual encoder (624) is configured to operate on the residual data to encode the residual data to generate transform coefficients. In one example, the residual encoder (624) is configured to transform the residual data from the spatial domain to the frequency domain to generate transform coefficients. The transform coefficients then undergo a quantization process to obtain quantized transform coefficients. In various embodiments, the video encoder (603) also includes a residual decoder (628). The residual decoder (628) is configured to perform an inverse transform and generate decoded residual data. The decoded residual data may be used by the intra-encoder (622) and the inter-encoder (630) as appropriate. For example, the inter-encoder (630) can generate decoded blocks based on the decoded residual data and the inter-prediction information, and the intra-encoder (622) can generate decoded blocks based on the decoded residual data and the intra-prediction information. In some examples, the decoded blocks are suitably processed to generate a decoded picture, which may be buffered in a memory circuit (not shown) and used as a reference picture.

[0069] The entropy encoder (625) is configured to format the bitstream to include the encoded block. The entropy encoder (625) is configured to include various information in accordance with an appropriate standard, such as the HEVC standard. In one example, the entropy encoder (625) is configured to include general control data, selected prediction information (e.g., intra-prediction information or inter-prediction information), residual information, and other appropriate information in the bitstream. It should be noted that, according to the disclosed subject matter, when encoding a block in a merged sub-mode of either an inter mode or a bi-prediction mode, no residual information is present.

[0070] 7 shows a diagram of a video decoder (710) according to another embodiment of the present disclosure. The video decoder (710) is configured to receive encoded pictures that are part of a coded video sequence and decode the encoded pictures to generate reconstructed pictures. In one example, the video decoder (710) is used in place of the video decoder (310) of the example of FIG. 3.

[0071] In the example of FIG. 7, the video decoder (710) includes an entropy decoder (771), an inter-decoder (780), a residual decoder (773), a reconstruction module (774), and an intra-decoder (772), coupled together as shown in FIG.

[0072] The entropy decoder (771) may be configured to reconstruct from the coded picture certain symbols representing syntax elements of which the coded picture is composed. Such symbols may include, for example, prediction information (e.g., intra- or inter-prediction information, etc.) that may identify the mode in which the block is coded (e.g., intra-mode, inter-mode, bi-prediction mode, merged sub-mode or the latter two of another sub-mode), certain samples or metadata used for prediction by the intra-decoder (772) or inter-decoder (780), respectively, residual information, e.g., in the form of quantized transform coefficients, etc. In one example, when the prediction mode is an inter-prediction mode or a bi-prediction mode, the inter-prediction information is provided to the inter-decoder (780), and when the prediction type is an intra-prediction type, the intra-prediction information is provided to the intra-decoder (772). The residual information may undergo inverse quantization and is provided to the residual decoder (773).

[0073] The inter decoder (780) is configured to receive the inter prediction information and to generate inter prediction results based on the inter prediction information.

[0074] The intra decoder (772) is configured to receive intra prediction information and to generate a prediction result based on the intra prediction information.

[0075] The residual decoder (773) is configured to perform inverse quantization to extract inverse quantized transform coefficients and process the inverse quantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (773) may also require certain control information (to include quantizer parameters (QP)), which may be provided by the entropy decoder (771) (the data path not shown as this may be only low volume control information).

[0076] The reconstruction module (774) is configured to combine, in the spatial domain, the residual as output by the residual decoder (773) and the prediction result (possibly as output by an inter- or intra-prediction module) to form a reconstruction block, which may be part of a reconstructed picture, which may then be part of the reconstructed video. It should be noted that other suitable operations, such as a deblocking operation, may be performed to improve visual quality.

[0077] It should be noted that the video encoders (303), (503), and (603) and the video decoders (310), (410), and (710) may be implemented using any suitable technology. In one embodiment, the video encoders (303), (503), and (603) and the video decoders (310), (410), and (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoders (303), (503), and (503) and the video decoders (310), (410), and (710) may be implemented using one or more processors executing software instructions.

[0078] Block-based compensation from different pictures may be called motion compensation. Block compensation may also be done from previously reconstructed regions of the same intra picture, which may be called intra-picture block compensation, intra-block copy (IBC), or current picture reference (CPR). For example, a displacement vector indicating an offset between a current block and a reference block is called a block vector. According to some embodiments, a block vector points to a reference block that has already been reconstructed and is available for reference. Also, for parallel processing considerations, reference regions beyond tile / slice boundaries or wavefront ladder boundaries may also be excluded from being referenced by block vectors. Due to these constraints, block vectors may be different from motion vectors in motion compensation, and motion vectors may be any value (positive or negative in either x or y direction).

[0079] The coding of block vectors may be explicit or implicit. In the explicit mode, sometimes called (Advanced Motion Vector Prediction) AMVP mode in inter-coding, the difference between the block vector and its prediction is signaled. In the implicit mode, the block vector is reconstructed from the prediction of the block vector in a similar manner to the motion vector in merge mode. The resolution of the block vector is limited to integer positions in some embodiments. In other embodiments, the resolution of the block vector can refer to fractional positions.

[0080] The use of intra block copy at the block level may be signaled using a block level flag, called the IBC flag. In one embodiment, the IBC flag is signaled when the current block is not encoded in merge mode. The IBC flag may also be signaled by a reference index approach, which is performed by treating the current decoded picture as a reference picture. In HEVC Screen Content Coding (SCC), such a reference picture is placed at the last position of the list. This special reference picture may be managed together with other temporal reference pictures of the DPB. IBC may also include variants such as flipped IBC (e.g., the reference block is flipped horizontally or vertically before being used to predict the current block), or line-based (IBC) (e.g., each compensation unit in an MxN coding block is Mx1 or 1xN line).

[0081] FIG. 8 illustrates an embodiment of intra-picture block compensation (e.g., intra-block copy mode). In FIG. 8, a current picture 800 includes a set of block regions that have already been coded / decoded (i.e., gray squares) and a set of block regions that have not yet been coded / decoded (i.e., white squares). One of the block regions that has not yet been coded / decoded, block 802, may be associated with a block vector 804 that points to another block 806 that has been previously coded / decoded. Thus, any motion information associated with block 806 may be used for coding / decoding block 802.

[0082] In some embodiments, the search range of the CPR mode is limited within the current CTU. The effective memory requirement for storing reference samples for the CPR mode is one CTU size of samples. Considering the existing reference sample memory to store reconstructed samples in the current 64x64 area, three or more 64x64 size reference sample memories are required. The embodiment of the present disclosure extends the effective search range of the CPR mode to a part of the left CTU while the total memory requirement for storing reference pixels remains unchanged (one CTU size, a total of four 64x64 reference sample memories).

[0083] In FIG. 9A, the top left region of the CTU 900 is the current region being decoded. When the top left region of the CTU 900 is decoded, entry [1] of the reference sample memory is overwritten with a sample from this region (e.g., the overwritten memory location has diagonal cross-hatching), as shown in FIG. 10A. In FIG. 9B, the top right region of the CTU 900 is the next current region being decoded. When the top right region of the CTU 900 is decoded, entry [2] of the reference sample memory is overwritten with a sample from this region, as shown in FIG. 10B. In FIG. 9C, the bottom left region of the CTU 900 is the next current region being decoded. When the bottom left region of the CTU 900 is decoded, entry [3] of the reference sample memory is overwritten with a sample from this region, as shown in FIG. 10C. In FIG. 9D, the bottom right region of the CTU 900 is the next current region being decoded. When the bottom right region of CTU 900 is decoded, reference sample memory entry [3] is overwritten with the sample from this region, as shown in FIG. 10D.

[0084] In some embodiments, bitstream compatibility conditions that valid block vectors (mvL, 1 / 16-pel resolution) should comply with the conditions specified below. In some embodiments, luma motion vectors mvL comply with the following constraints A1, A2, B1, C1, and C2.

[0085] In the first constraint (A1), when the block availability (e.g., neighboring block availability check process) derivation process is called with the current luma position (xCurr, yCurr) set equal to (xCb, yCb) and the neighboring luma position (xCb+(mvL[0]>>4)+cbWidth-1, yCb+(mvL[1]>>4)+cbHeight-1) as input, the output should be equal to TRUE.

[0086] In the second constraint (A2), when the block availability (e.g., neighboring block availability check process) derivation process is called with the current luma position (xCurr, yCurr) set equal to (xCb, yCb) and the neighboring luma position (xCb+(mvL[0]>>4)+cbWidth-1, yCb+(mvL[1]>>4)+cbHeight-1) as input, the output should be equal to TRUE.

[0087] In the third constraint (B1), one or both of the following conditions are true: (i) The value of (mvL[0]>>4)+cbWidth is less than or equal to 0. (ii) The value of (mvL[1]>>4)+cbHeight is less than or equal to 0.

[0088] In the fourth constraint (C1), the following condition is true: (i)(yCb+(mvL[1]>>4))>>CtbLog2SizeY=yCb>>CtbLog2SizeY (ii)(yCb+(mvL[1]>>4)+cbHeight-1)>>CtbLog2SizeY=yCb>>CtbLog2SizeY (iii)(xCb+(mvL[0]>>4))>>CtbLog2SizeY>=(xCb>>CtbLog2SizeY)-1 (iv)(xCb+(mvL[0]>>4)+cbWidth-1)>>CtbLog2SizeY<=(xCb>>CtbLog2SizeY)

[0089] In the fifth constraint (C2), if (xCb+(mvL[0]>>4))>>CtbLog2SizeY is equal to (xCb>>CtbLog2SizeY)-1, then a derivation process for block availability (e.g., neighboring block availability check process) is invoked with input the current luma position (xCurr, yCurr) set equal to (xCb, yCb) and neighboring luma positions (((xCb+(mvL[0]>>4))>>(CtbLog2SizeY-1))<<(CtbLog2SizeY-1), ((yCb+(mvL[1]>>4))>>(CtbLog2SizeY-1))<<(CtbLog2SizeY-1)) and output is equal to FALSE.

[0090] In the above equation, xCb and yCb are the x and y coordinates of the current block, respectively. The variables cbHeight and cbWidth are the height and width of the current block, respectively. The variable CtbLog2sizeY refers to the CTU size in the log2 domain. For example, CtbLog2sizeY=7 means that the CTU size is 128x128. The variables mvL0[0] and mvL0[1] refer to the x and y components of the block vector mvL0, respectively. If the output is FALSE, it is determined that the samples of the reference block are available (e.g., the neighboring block is available for intra block copy use). If the output is TRUE, it is determined that the samples of the reference block are not available.

[0091] According to some embodiments, the History-Based MVP (HMVP) method includes an HMVP candidate defined as the motion information of a previously coded block. A table with multiple HMVP candidates is maintained during the coding / decoding process. When a new slice is encountered, the table is emptied. Whenever an inter-coded non-affine block exists, the associated motion information is added to the last entry of the table as a new HMVP candidate. The coding flow of the HMVP method is illustrated in FIG. 11A.

[0092] The table size S is set to 6, indicating that up to six HMVP candidates may be added to the table. When inserting a new motion candidate into the table, a constrained FIFO rule is utilized such that a redundancy check is first applied to determine whether an identical HMVP is in the table. If found, the identical HMVP is removed from the table, and then all HMVP candidates are moved forward (i.e., their indexes are decreased by 1). Figure 11B shows an example of inserting a new motion candidate into the HMVP table.

[0093] In the merge candidate list construction process, HMVP candidates may be used. The most recent few HMVP candidates in the table are checked in order and inserted into the candidate list after the TMVP candidate. Pruning may be applied to HMVP candidates for spatial or temporal merge candidates except for sub-block motion candidates (i.e., ATMVP).

[0094] In some embodiments, to reduce the number of pruning operations, the number of HMPV candidates to be checked (denoted by L) is set as L=(N<=4)?M:(8-N), where N denotes the number of available non-subblock merge candidates and M denotes the number of available HMVP candidates in the table. In addition, the merge candidate list construction process from the HMVP list ends when the total number of available merge candidates reaches the signaled maximum allowed merge candidate minus 1. Furthermore, the number of pairs for combined bi-predictive merge candidate derivation is reduced from 12 to 6.

[0095] HMVP candidates may also be used in the AMVP candidate list construction process. After the TMVP candidates, the motion vectors of the last K HMVP candidates in the table are inserted. Only HMVP candidates with the same reference picture as the AMVP target reference picture are used to construct the AMVP candidate list. Pruning is applied to the HMVP candidates. In some applications, K is set to 4 while the AMVP list size remains unchanged (i.e., equal to 2).

[0096] According to some embodiments, when intra block copy operates as a separate mode from inter mode, a separate history buffer, called HBVP, may be used to store previously coded intra block copy block vectors. As a separate mode from inter prediction, it is desirable to have a simplified block vector derivation process for intra block copy mode. The candidate list for IBC BV prediction in AMVP mode may share the one used in IBC merge mode (merge candidate list) with 2 spatial candidates + 5 HBVP candidates.

[0097] The merge candidate list size for IBC mode may be assigned as MaxNumMergeCand, which may be determined by the inter mode merge candidate list size MaxNumMergeCand, which in some examples is specified as six_minus_max_num_merge_cand. The variable six_minus_max_num_merge_cand may specify the maximum number of merge motion vector prediction (MVP) candidates supported in a slice subtracted from six.

[0098] In some examples, the maximum number of merge MVP candidates, MaxNumMergeCand, may be derived as follows: Formula (1): MaxNumMergeCand=6-six_minus_max_num_merge_cand

[0099] The value of MaxNumMergeCand may range from 1 to 6 inclusive. In some video coding systems, the merge list size for IBC mode is signaled separately from the merge list size for inter merge mode for all I / P / B slices. The range of this size may be the same as for inter merge mode (e.g., 1 to 6 inclusive). In some examples, the maximum number of IBC candidates, MaxNumIbcMergeCand, may be derived as follows: Formula (2): MaxNumIBCMergeCand=6-six_minus_max_num_ibc_merge_cand

[0100] In equation (2), the variable six_minus_max_num_ibc_merge_cand specifies the maximum number of IBC merge motion vector prediction (MVP) candidates supported in a slice subtracted from six. The value of MaxNumIBCMergeCand may range from 1 to 6 inclusive. In some video coding systems, the merge index signaling for IBC merge mode may still share the merge index signaling used for inter merge mode. In this regard, IBC merge mode and inter merge mode may share the same syntax element for the merge index. The merge index is binarized using a truncated rice (TR) code, so the maximum length of the merge index is MaxNumMergeCand-1. However, if MaxNumIbcMergeCand is not equal to MaxNumMergeCand, a solution for merge index signaling is needed.

[0101] The embodiments of the present disclosure may be used separately or combined in any order. Moreover, each of the methods, encoders, and decoders according to the embodiments of the present disclosure may be implemented by a processing circuit (e.g., one or more processors or one or more integrated circuits). In one example, the one or more processors execute a program stored in a non-transitory computer-readable medium. According to some embodiments, the term block may be interpreted as a prediction block, a coding block, or a coding unit (i.e., CU).

[0102] According to some embodiments, the number of maximum merge sizes for the merge index binarization is set to be switchable between the number of MaxNumMergeCand and the number of MaxNumIbcMergeCand. For example, if the current block is encoded in IBC mode, the maximum merge size of the merge index is MaxNumIbcMergeCand. However, if the current block is not encoded in IBC mode, the maximum merge size of the merge index is MaxNumMergeCand. Table 1 shows examples of syntax elements and associated binarizations.

[0103] [Table 1]

[0104] As shown in Table 1, the binarization of the merge index (i.e., merge_idx[][]) is based on whether the current block is encoded in IBC mode. Furthermore, FL refers to the fixed length, cMax refers to the maximum possible value of the variable length code, and eRiceParam is the Rice parameter of the variable length code. The Rice parameter can be used to determine the binary code of each input value. For truncated binary codes, the Rice parameter is 0.

[0105] According to some embodiments, the number of maximum merge sizes of merge index binarization is set to the maximum number between MaxNumMergeCand and MaxNumIbcMergeCand. For I slice / tile group, the value of MaxNumMergeCand is not signaled, so MaxNumMergeCand can have a guess value of 1 (i.e., the minimum possible value of MaxNumIbcMergeCand). Thus, when MaxNumMergeCand is not signaled, the value of MaxNumMergeCand is guessed to be 1, so the value of six_minus_max_num_merge_cand is guessed to be 5. Thus, in equation (1), six_minus_max_num_merge_cand is 5, so MaxNumMergeCand is equal to 1. In equation (2), the value of MaxNumIbcMergeCand is in the range of 1 to 6.

[0106] Table 2 shows examples of constructs and associated binarizations.

[0107] [Table 2]

[0108] As shown in Table 2, the binarization of the merge index (i.e., merge_idx[][]) is based on whether the maximum number of merge mode candidates (i.e., MaxNumMergeCand) is greater than the maximum number of IBC candidates (i.e., MaxNumIbcMergeCand).

[0109] According to some embodiments, the range of MaxNumIbcMergeCand shall be less than or equal to MaxNumMergeCand. For I slice / tile groups, the value of MaxNumMergeCand is not signaled, so the value of MaxNumMergeCand is inferred to be 6. Thus, in equation (1), MaxNumMergeCand is inferred to be 6, so the value of six_minus_max_num_merge_cand is inferred to be 0. In some embodiments, if the signaled MaxNumIbcMergeCand value is greater than MaxNumMergeCand, MaxNumIbcMergeCand is clipped to MaxNumMergeCand. Thus, in equation (2), if the slice type is I, the value of MaxNumIbcMergeCand shall be in the range from 1 to 6, inclusive. However, if the slice type is P or B, the value of MaxNumIbcMergeCand shall be in the range from 1 to 6, inclusive. Thus, if the slice type is P or B (ie, MaxNumMergeCand is not signaled), the value of MaxNumIbcMergeCand may be determined as follows: MaxNumIbcMergeCand=min(MaxNumIbcMergeCand, MaxNumMergeCand).

[0110] 12 illustrates one embodiment of a video decoding process performed by a video decoder, such as the video decoder (710). The process may begin at step (S1200) where a coded video bitstream containing a current picture is received. The process proceeds to step (S1202) where a predetermined condition associated with signaling data included in the coded video bitstream is determined.

[0111] The process proceeds to step (S1204), where, based on a predetermined condition, a size of an index included in the signaling data of the candidate list for vector prediction is set to either the maximum number of merge mode candidates or the number of IBC candidates. As an example, the index may be a merge index included in the coded video bitstream. As an example, the predetermined condition includes determining whether the current block is encoded in IBC mode. If the current block is encoded in IBC mode, the size of the index is set to MaxNumIbcMergeCand. However, if the current block is not encoded in IBC mode, the size of the index is set to MaxNumMergeCand.

[0112] As another example, the predetermined condition includes determining whether the maximum number of merge mode candidates is greater than the maximum number of IBC candidates. If the maximum number of merge mode candidates is greater than the maximum number of IBC candidates, the size of the index is set to MaxNumMergeCand. However, if the maximum number of merge mode candidates is less than the maximum number of IBC candidates, the size of the index is set to MaxNumIbcMergeCand.

[0113] The process proceeds from step (S1204) to (S1206), where a candidate list is created with vector prediction. For example, if the current block is encoded in merge mode, the candidate list is a merge list and the vector prediction is a motion vector. In another example, if the current block is encoded in IBC mode, the candidate list is a list of block vector predictions. The process proceeds from step (S1208), where a vector prediction is retrieved from the candidate list according to an index having a value that does not exceed the determined size of the index. For example, the value of the index used to retrieve the vector prediction from the candidate list cannot exceed the determined size of the index in step (S1204). The process proceeds to step (S1210), where the current block is decoded according to the retrieved vector prediction.

[0114] FIG. 13 illustrates an embodiment of a video decoding process performed by a video decoder, such as the video decoder (710). The process may begin at step (S1300) where a coded video bitstream including a current picture is received. The process proceeds to step (S1302) where signaling data from the coded video bitstream is retrieved for a current block. The process proceeds to step (S1304) where it is determined whether the retrieved signaling data for the current block includes a maximum number of merge candidates. For example, it is determined whether MaxNumMergeCand is signaled. As mentioned above, in some examples, MaxNumMergeCand is not signaled for I slice / tile group types, but is signaled for P or B slice / tile group types.

[0115] The process proceeds to step (S1306), where the maximum number of intra block copy (IBC) candidates is set based on a determination of whether the signaling data for the current block includes a maximum number of merge candidates. For example, if MaxNumMergeCand is not signaled, then the value of MaxNumIbcMergeCand ranges from 1 to 6. However, if MaxNumMergeCand is signaled, then the value of MaxNumIbcMergeCand ranges from 1 to MaxNumMergeCand.

[0116] In some examples, a coding unit includes samples of both luma and chroma components. These samples of the chroma components can have an independent or separate split tree structure compared to one of the luma components. In some examples, the separate coding tree structure starts from the CTU level. Thus, a chroma CU (e.g., a CU that includes only two chroma components) can be larger than its luma counterpart at the corresponding sample position.

[0117] According to some embodiments, in a first method, when a dual tree structure is used, a chroma block can be encoded in IBC mode if at least the following conditions are met: 1. For each sub-block region of a chroma CU, the collocator region is encoded in IBC mode. 2. All colocator lua region samples of a chroma CU have the same block vector. 3. The derived common block vector for the entire chroma CU is a valid BV, i.e., this BV points to an already reconstructed region of the current picture within the given constraint region for the chroma components.

[0118] Based on the first method, the decoder side can treat the chroma CU as a whole CU, not as a subblock-based CU, so it is sufficient to use a single derived BV from the collocator region (e.g., usually the top-left corner of the CU) to decode the CU.

[0119] According to some embodiments, in the second method, when a dual tree structure is used, a different condition may be used to enable the use of chroma IBC mode in the dual tree structure. In one embodiment, a chroma block may be encoded in IBC mode when (i) corresponding luma samples of all chroma samples belong to the same luma coding block, and (ii) the same luma coding block is encoded in IBC mode. As an example, this condition is checked by evaluating two corners of a chroma CU. If the luma correspondence of the top-left chroma sample and the luma correspondence of the bottom-right chroma sample belong to the same luma coding block, then the entire corresponding luma region of the chroma CU belongs to the same luma coding block. In another embodiment, a chroma block may be encoded in IBC mode when the corresponding luma coding is performed.

[0120] Based on the second method, the decoder side can treat the chroma CU as a whole CU, not as a subblock-based CU, so it is sufficient to use a single derived BV from the collocator region (usually the top-left corner of the CU) to decode the CU.

[0121] According to some embodiments, for either the first method or the second method for a dual tree structure, the non-limiting embodiments disclosed below show how to signal the use of chroma IBC mode in a dual tree when the above conditions in either the first method or the second method are met.

[0122] In one embodiment, the above constraints for using IBC mode for chroma CUs with a dual tree structure are implemented such that a usage flag (e.g., ibc_flag) is signaled for each chroma CU when applicable. However, in this embodiment, ibc_flag is signaled as true only when all conditions of the first method or all conditions of the second method are met. Otherwise, ibc_flag is signaled as false. In some examples, when all conditions for either the first method or the second method are met, ibc_flag can also be signaled as false based on how the encoder is implemented.

[0123] In another embodiment, the above constraints for using IBC mode for a chroma CU with a dual tree structure are implemented such that the usage flag (e.g., ibc_flag) is not signaled at all. For example, for a chroma CU with a dual tree structure, if all the conditions of the first method or the second method are met, the CU is encoded in IBC mode and ibc_flag is inferred as true. Otherwise, ibc_flag is not signaled and is inferred as false.

[0124] The techniques described above may be implemented using computer readable instructions and as computer software physically stored on one or more computer readable media. For example, Figure 14 illustrates a computer system (1400) suitable for implementing certain embodiments of the disclosed subject matter.

[0125] Computer software can be encoded using any suitable machine code or computer language, which may rely on assembly, compiling, linking, or similar mechanisms, to create code including instructions that can be executed by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., directly, or through interpretation, microcode execution, etc.

[0126] The instructions may be executed on various types of computers or components thereof including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, Internet of Things devices, and the like.

[0127] 14 for computer system (1400) are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing the embodiments of the present disclosure. Neither the arrangement of components should be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary embodiment of computer system (1400).

[0128] The computer system (1400) may include certain human interface input devices. Such human interface input devices may respond to input by one or more human users, for example, via tactile input (keystrokes, swipes, data glove movements, etc.), audio input (voice, clapping, etc.), visual input (gestures, etc.), olfactory input (not shown). Human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (voice, music, ambient sounds, etc.), images (scanned images, photographic images obtained from a still camera, etc.), and video (two-dimensional video, three-dimensional video including stereoscopic video, etc.).

[0129] The input human interface devices may include one or more (only one of each shown) of a keyboard (1401), a mouse (1402), a trackpad (1403), a touch screen (1410), a data glove (not shown), a joystick (1405), a microphone (1406), a scanner (1407), and a camera (1408).

[0130] The computer system (1400) may also include certain human interface output devices. Such human interface output devices may stimulate one or more of the human user's senses, for example, through haptic output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via a touch screen (1410), data gloves (not shown), or joystick (1405), although there may also be haptic feedback devices that do not function as input devices), audio output devices (such as speakers (1409), headphones (not shown)), visual output devices (such as screens (1410), including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input capability, each with or without haptic feedback capability, some of which may output two-dimensional visual output or output in more than three dimensions, such as through means of stereographic output, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown).

[0131] The computer system (1400) may include human accessible storage devices and their associated media, such as optical media (1420) including CD / DVD ROM / RW along with media such as CDs / DVDs (1421), thumb drives (1422), removable hard drives or solid state drives (1423), legacy magnetic media such as tapes and floppy disks (not shown), specialized ROM / ASIC / PLD based devices such as security dongles (not shown), etc.

[0132] Those skilled in the art will also understand that the term "computer-readable medium" as used in connection with the presently disclosed subject matter does not include transmission media, carrier waves, or other transitory signals.

[0133] The computer system (1400) may also include interfaces to one or more communication networks. The networks may be, for example, wireless, wired, optical. The networks may further be local, wide area, metropolitan, vehicular and industrial, real-time, delay tolerant, etc. Examples of networks include local area networks such as Ethernet, cellular networks including wireless LAN, GSM, 3G, 4G, 5G, LTE, etc., TV wired or wireless wide area digital networks including cable TV, satellite TV, terrestrial broadcast TV, and vehicular and industrial including CANBus, etc. Certain networks generally require an external network interface adapter connected to a particular general data port or peripheral bus (1449) (e.g., a USB port on the computer system (1400)), while others are generally integrated into the core of the computer system (1400) by connection to a system bus as described below (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). Using any of these networks, the computer system (1400) can communicate with other entities. Such communications may be unidirectional, receive only (e.g., TV broadcast), unidirectional transmit only (e.g., CANbus to a particular CANbus device), or bidirectional, e.g., to other computer systems using local or wide area digital networks. As noted above, specific protocols and protocol stacks may be used in each of these networks and network interfaces.

[0134] The aforementioned human interface devices, human accessible storage devices, and network interfaces may be connected to the core (1440) of the computer system (1400).

[0135] The cores (1440) may include one or more central processing units (CPUs) (1441), graphics processing units (GPUs) (1442), specialized programmable processing units (1443) in the form of field programmable gate areas (FPGAs), hardware accelerators (1444) for specific tasks, and the like. These devices may be connected through a system bus (1448), along with read-only memory (ROM) (1445), random access memory (1446), internal mass storage (1447) such as an internal hard drive or SSD that is not accessible to the user. In some computer systems, the system bus (1448) is accessible in the form of one or more physical plugs, allowing expansion with additional CPUs, GPUs, and the like. Peripheral devices may be connected directly to the core's system bus (1448) or through a peripheral bus (1449). Peripheral bus architectures include PCI, USB, and the like.

[0136] The CPU (1441), GPU (1442), FPGA (1443), and accelerator (1444) may combine to execute certain instructions that may constitute the aforementioned computer code. That computer code may be stored in ROM (1445) or RAM (1446). Transient data may also be stored in RAM (1446), while permanent data may be stored, for example, in internal mass storage (1447). Rapid storage and retrieval to any memory device may be enabled through the use of cache memory, which may be closely associated with one or more of the CPU (1441), GPU (1442), mass storage (1447), ROM (1445), RAM (1446), etc.

[0137] The computer-readable media may have computer code thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those skilled in the computer software arts.

[0138] As an example, and not by way of limitation, a computer system (1400) having an architecture, specifically a core (1440), can provide functionality as a result of a processor (including a CPU, GPU, FPGA, accelerator, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media can be media associated with user-accessible mass storage as introduced above, as well as specific storage of the core (1440) of a non-transitory nature, such as the core internal mass storage (1447) or ROM (1445). Software implementing various embodiments of the present disclosure can be stored in such devices and executed by the core (1440). The computer-readable media can include one or more memory devices or chips, depending on the particular needs. The software can cause the core (1440), and in particular the processor therein (including a CPU, GPU, FPGA, etc.) to perform certain processes or certain parts of certain processes described herein, including the definition of data structures stored in RAM (1446) and the modification of such data structures by the software-defined processes. Additionally or alternatively, the computer system may provide functionality as a result of logic hardwired or otherwise embodied in circuitry (e.g., accelerator (1444)) that may operate in place of or together with software to perform certain processes or certain portions of certain processes described herein. References to software may include logic, and vice versa, as appropriate. References to computer-readable media may encompass circuitry (such as integrated circuits (ICs)) that stores software for execution, circuitry that embodies logic for execution, or both, as appropriate. The present disclosure encompasses any suitable combination of hardware and software.

[0139] Appendix A: Acronyms JEM Joint Exploration Model VVC Versatile Video Coding BMS Benchmark Set MV Motion Vector HEVC High Efficiency Video Coding SEI Supplemental Enhancement Information VUI Video Usability Information GOP Group of Pictures TU conversion unit, PU Prediction Unit CTU Coding Tree Unit CTBs coding tree blocks PB Predicted Block HRD Hypothetical Reference Decoder SNR Signal to Noise Ratio CPU Central Processing Unit GPU Graphics Processing Unit CRT cathode ray tube LCD Liquid Crystal Display OLED Organic Light Emitting Diode CD Compact Disc DVD Digital Video Disc ROM Read Only Memory RAM Random Access Memory ASIC Application Specific Integrated Circuit PLD Programmable Logic Device LAN Local Area Network GSM Global System for Mobile Communications LTE Long Term Evolution CANBus Controller Area Network Bus USB Universal Serial Bus PCI Peripheral Component Interconnect FPGA Field Programmable Gate Area SSD Solid State Drive IC Integrated Circuit CU coding unit

[0140] While this disclosure describes several exemplary embodiments, there are modifications, permutations, and various substitute equivalents that are within the scope of this disclosure. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within its spirit and scope.

[0141] (1) A method for video decoding includes the steps of receiving a coded video bitstream including a current picture, determining a predetermined condition associated with signaling data included in the coded video bitstream, determining a size of an index included in the signaling data for a candidate list for vector prediction based on the predetermined condition and based on a number of merge mode candidates and a number of intra block copy (IBC) candidates, creating a candidate list with vector prediction, retrieving a vector prediction from the candidate list according to an index having a value not exceeding the determined size of the index, and decoding the current block using the retrieved vector prediction.

[0142] (2) The method of video decoding according to feature (1), wherein the predetermined condition includes determining whether the current block is encoded in IBC mode.

[0143] (3) A method of video decoding according to feature (2), in response to determining that the current block is encoded in IBC mode, setting a size of the index to a maximum number of IBC candidates, and in response to determining that the current block is not encoded in IBC mode, setting a size of the index to the maximum number of merge mode candidates.

[0144] (4) A method of video decoding according to any one of features (1) to (3), wherein the predetermined condition includes determining whether a maximum number of merge mode candidates is greater than a maximum number of IBC candidates.

[0145] (5) In response to determining that the maximum number of merge mode candidates is greater than the maximum number of IBC candidates, setting a size of an index to the maximum number of merge mode candidates, and in response to determining that the maximum number of merge mode candidates is less than the maximum number of IBC candidates, setting a size of an index to the maximum number of IBC candidates.

[0146] (6) A method for video decoding includes the steps of receiving a coded video bitstream including a current picture, extracting signaling data from the coded video bitstream for a current block, determining whether the extracted signaling data for the current block includes a maximum number of merging candidates, and setting a maximum number of intra block copy (IBC) candidates based on a determination of whether the signaling data for the current block includes the maximum number of merging candidates.

[0147] (7) The method of video decoding according to feature (6), wherein, in response to determining that the signaling data does not include a maximum number of merging candidates, the maximum number of IBC candidates is set to a value greater than or equal to 1 and less than or equal to 6.

[0148] (8) The method of video decoding according to feature (7), wherein, in response to determining that the maximum number of merging candidates is included in the signaling data, the maximum number of IBC candidates is set to a value between 1 and the maximum number of merging candidates.

[0149] (9) A video decoding device for video decoding includes a processing circuit configured to receive a coded video bitstream including a current picture, determine a predetermined condition associated with signaling data included in the coded video bitstream, determine a size of an index included in the signaling data for a candidate list for vector prediction based on a number of merge mode candidates and a number of intra block copy (IBC) candidates based on the predetermined condition, create a candidate list with the vector prediction, retrieve a vector prediction from the candidate list according to an index having a value not exceeding the determined size of the index, and decode the current block according to the retrieved vector prediction.

[0150] (10) The video decoding apparatus according to feature (9), further comprising: a processing circuit configured to determine whether the predetermined condition is that the current block is encoded in IBC mode.

[0151] (11) In response to a determination that the current block is encoded in IBC mode, the processing circuitry is configured to set a size of the index to the maximum number of IBC candidates, and in response to a determination that the current block is not encoded in IBC mode, the processing circuitry is configured to set a size of the index to the maximum number of merge mode candidates.

[0152] (12) The video decoding device according to any one of features (9) to (12), wherein the predetermined condition includes determining whether a maximum number of merge mode candidates is greater than a maximum number of IBC candidates.

[0153] (13) The video decoding apparatus of feature (12), wherein in response to a determination that the maximum number of merge mode candidates is greater than the maximum number of IBC candidates, the processing circuitry is further configured to set a size of the index to the maximum number of merge mode candidates, and in response to a determination that the maximum number of merge mode candidates is less than the maximum number of IBC candidates, the processing circuitry is further configured to set a size of the index to the maximum number of IBC candidates.

[0154] (14) A video decoder apparatus for video decoding, comprising: a processing circuit configured to receive a coded video bitstream including a current picture, extract signaling data from the coded video bitstream for a current block, determine whether a maximum number of merging candidates is included in the extracted signaling data for the current block, and set a maximum number of intra block copy (IBC) candidates based on a determination of whether the maximum number of merging candidates is included in the signaling data for the current block.

[0155] (15) The video decoder of feature (14), wherein in response to determining that the signaling data does not include a maximum number of merging candidates, the maximum number of IBC candidates is set to a value greater than or equal to 1 and less than or equal to 6.

[0156] (16) The video decoder according to feature (15), wherein in response to determining that the maximum number of merging candidates is included in the signaling data, the maximum number of IBC candidates is set to a value between 1 and the maximum number of merging candidates.

[0157] (17) A non-transitory computer-readable medium storing instructions that, when executed by a processor of a video decoder, cause the processor to perform a method including: receiving a coded video bitstream including a current picture; determining a predetermined condition associated with signaling data included in the coded video bitstream; determining a size of an index included in the signaling data for a candidate list for vector prediction based on the predetermined condition and based on a number of merge mode candidates and a number of intra block copy (IBC) candidates; creating a candidate list with vector prediction; retrieving a vector prediction from the candidate list according to an index having a value not exceeding the determined size of the index; and decoding the current block according to the retrieved vector prediction.

[0158] (18) The non-transitory computer-readable medium according to feature (17), comprising determining whether a predetermined condition determines whether the current block is encoded in IBC mode.

[0159] (19) A non-transitory computer-readable medium storing instructions that, when executed by a processor of a video decoder, cause the processor to perform a method including the steps of receiving a coded video bitstream including a current picture; extracting signaling data from the coded video bitstream for a current block; determining whether the signaling data extracted for the current block includes a maximum number of merging candidates; and setting a maximum number of intra block copy (IBC) candidates based on a determination of whether the signaling data for the current block includes the maximum number of merging candidates.

[0160] (20) The non-transitory computer-readable medium according to feature (19), wherein in response to determining that the signaling data does not include the maximum number of merging candidates, the maximum number of IBC candidates is set to a value greater than or equal to 1 and less than or equal to 6. [Explanation of symbols]

[0161] 101 Current Block 102 Samples 103 Samples 104 Samples 105 Samples 106 Samples 200 Communication Systems 210 Terminal Devices 220 Terminal Devices 230 Terminal Devices 240 Terminal Devices 250 Network 300 Communication Systems 301 Video Source 302 Video Picture Stream 303 Video Encoder 304 coded video data 305 Streaming Server 306 Client Subsystem 307 Coded Video Data 308 Client Subsystem 309 Coded Video Data 310 Video Decoder 311 Video Picture Output Stream 312 Display 313 Capture Subsystem 320 Electronic Devices 330 Electronic Devices 401 Channel 410 Video Decoder 412 Rendering Device 415 Buffer Memory 420 Parser 421 Symbols 430 Electronic Devices 431 Receiver 451 Scaler / Inverse Conversion Unit 452 intra prediction units 453 Motion Compensation Prediction Unit 455 Aggregator 456 Loop Filter Unit 457 Reference Picture Memory 458 Current Picture Buffer 501 Video Sources 503 Video Encoder 520 Electronic Devices 530 Source Coder 532 Coding Engine 533 Decoder 534 Reference Picture Memory 535 Predictions 540 Transmitter 543 coded video sequence 545 Entropy Coder 550 Controller 560 Channels 603 Video Encoder 621 General Controller 622 Intra Encoder 623 Residual calculation section 624 Residual Encoder 625 Entropy Encoder 626 Switch 628 Residual Decoder 630 InterEncoder 710 Video Decoder 771 Entropy Decoder 772 Intra Decoder 773 Residual Decoder 774 Reconstruction Module 780 Inter Decoder 800 Current Picture 802 Block 804 Block Vector 806 Block 900 Coding Tree Units (CTU) 1400 Computer Systems 1401 Keyboard 1402 Mouse 1403 Trackpad 1405 Joystick 1406 Mike 1407 Scanner 1408 Camera 1409 Output Device 1410 Screen 1420 Optical media including CD / DVD ROM / RW 1421 DVDs and other media 1422 Thumb Drive 1423 Removable Hard Drive or Solid State Drive 1440 cores 1441 Central Processing Unit (CPU) 1442 Graphics Processing Unit (GPU) 1443 Field Programmable Gate Area (FPGA) 1444 Hardware accelerators for specific tasks 1445 Read-Only Memory (ROM) 1446 Random Access Memory 1447 Internal Mass Storage 1448 System Bus 1449 Surrounding Bus 1450 Graphics Adapter 1454 Network Interface

Claims

1. receiving a coded video bitstream including a current picture; determining a merge index associated with signaling data included in the coded video bitstream, determining whether the current block is encoded in intra block copy (IBC) mode; determining a maximum value cMax of the merge index based on the determining step, the cMax being determined based on a maximum number of merge mode candidates (MaxNumMergeCand) or a maximum number of IBC merge candidates (MaxNumIbcMergeCand); and determining a size of an index included in the signaling data for a candidate list for vector prediction based on the maximum number of merge mode candidates and the maximum number of IBC candidates; creating the candidate list by vector prediction; removing a vector prediction from the candidate list according to the index having a value not exceeding the determined size of the index; decoding the current block according to the retrieved vector prediction; A method for video decoding, comprising:

2. The method described in claim 1, wherein if the current block is not encoded in the IBC mode, cMax is set to the maximum number of merge mode candidates minus 1.

3. The method of claim 1, wherein if the current block is encoded in IBC mode, cMax is set to the maximum number of IBC candidates minus 1.

4. A video decoding device for video decoding, comprising: receiving a coded video bitstream including a current picture; determining a merge index associated with signaling data included in the coded video bitstream, Determining whether the current block is encoded in intra block copy (IBC) mode; determining a maximum value of the merge index, cMax, based on the determining, wherein the cMax is determined based on a maximum number of merge mode candidates (MaxNumMergeCand) or a maximum number of IBC merge candidates (MaxNumIbcMergeCand); and determining a size of an index included in the signaling data for a candidate list for vector prediction based on the maximum number of merge mode candidates and the maximum number of IBC candidates; creating said candidate list with vector prediction; retrieving a vector prediction from the candidate list according to the index having a value not exceeding the determined size of the index; decoding the current block according to the retrieved vector prediction; 16. An apparatus comprising: a processing circuit configured to:

5. The apparatus of claim 4, wherein if the current block is not encoded in the IBC mode, cMax is set to the maximum number of merge mode candidates minus 1.

6. The apparatus of claim 4, wherein if the current block is encoded in IBC mode, cMax is set to the maximum number of IBC candidates minus 1.

7. A non-transitory computer-readable medium, comprising: When executed by a processor of a video decoder, the processor is caused to: receiving a coded video bitstream including a current picture; determining a merge index associated with signaling data included in the coded video bitstream, determining whether the current block is encoded in intra block copy (IBC) mode; determining a maximum value cMax of the merge index based on the determining step, the cMax being determined based on a maximum number of merge mode candidates (MaxNumMergeCand) or a maximum number of IBC merge candidates (MaxNumIbcMergeCand); and determining a size of an index included in the signaling data for a candidate list for vector prediction based on the maximum number of merge mode candidates and the maximum number of IBC candidates; creating the candidate list by vector prediction; removing a vector prediction from the candidate list according to the index having a value not exceeding the determined size of the index; decoding the current block according to the retrieved vector prediction; A non-transitory computer readable medium storing instructions for performing a method including:

8. The non-transitory computer-readable medium of claim 7, wherein if the current block is not encoded in the IBC mode, cMax is set to the maximum number of merge mode candidates minus 1.

9. A non-transitory computer-readable medium as described in claim 7 or 8, wherein if the current block is encoded in IBC mode, cMax is set to the maximum number of IBC candidates minus 1.

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