Video coding and decoding method and device, readable medium and computer system

Abstract

Aspects of the present disclosure provide a method, apparatus, readable medium, and computer system for video decoding. An apparatus for video decoding includes processing circuitry. Processing circuitry may decode a first syntax element from an encoded video bitstream, the first syntax element signaled in a first codec level, the first syntax element indicating a maximum number of merge motion vector prediction (MVP) candidates, the first codec level being higher than a picture parameter set (PPS) level. Processing circuitry may determine the maximum number of the merge MVP candidates based on the first syntax element. Processing circuitry may reconstruct a coded block associated with the first codec level based at least on the maximum number of merge MVP candidates. The first codec level is a sequence level, and the first syntax element is signaled in a sequence parameter set (SPS).

Description

[0001] Introduce and use

[0002] This application claims priority to U.S. Patent Application No. 17 / 088,073, filed on November 3, 2020, "METHOD AND APPARATUS FOR VIDEO CODING," which claims priority to U.S. Provisional Application No. 62 / 960,930, filed on January 14, 2020, "SIGNALING OF MAXIMUM NUMBER OF MERGE CANDIDATES FOR INTERPREDICTION." The entire disclosures of these prior applications are hereby incorporated by reference in their entirety. Technical Field

[0003] This application describes embodiments generally related to video encoding and decoding. Background Art

[0004] The background description provided herein is intended to present the background of the present application as a whole. The extent to which the work of the presently named inventors described in the background section and various aspects of this specification is performed does not indicate that it is prior art at the time of filing this application, and it is never explicitly or implicitly admitted that it is prior art for this application.

[0005] Video encoding and decoding are made possible by inter-picture prediction techniques with motion compensation. An uncompressed digital video may include a series of pictures, each picture having a spatial dimension of, for example, 1920×1080 luminance samples and associated chrominance samples. The series of pictures has a fixed or variable picture rate (also informally referred to as a frame rate), for example, 60 pictures per second or 60Hz. Uncompressed video has very large bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 luminance sample resolution, 60Hz frame rate) with 8 bits per sample requires close to 1.5Gbit / s bandwidth. One hour of such video requires more than 600GB of storage space.

[0006] One goal of video encoding and decoding is to reduce redundant information in the input video signal through compression. Video compression can help reduce the bandwidth or storage space requirements mentioned above, in some cases by two or more orders of magnitude. Both lossless and lossy compression, as well as combinations of the two, can be used. Lossless compression refers to techniques that reconstruct an exact replica of the original signal from the compressed original signal. When lossy compression is used, the reconstructed signal may not be exactly the same as the original signal, but the distortion between the original and the reconstructed signal is small enough that the reconstructed signal can be used for the intended application. Lossy compression is widely used in video. The amount of distortion allowed depends on the application. For example, users of some consumer streaming applications may tolerate higher distortion than users of television applications. The achievable compression ratio reflects that higher allowed / tolerable distortion results in higher compression ratios.

[0007] Motion compensation may be a lossy compression technique and may involve a technique where a block of sample data from a previously reconstructed picture or part thereof (reference picture) is used to predict a newly reconstructed picture or part of a picture after being spatially shifted in a direction indicated by a motion vector (hereinafter MV). In some cases, the reference picture may be the same as the picture currently being reconstructed. The MV may have two dimensions: an X dimension and a Y dimension, or three dimensions, with the third dimension being used to indicate the reference picture in use (the latter may indirectly be a temporal dimension).

[0008] In some video compression techniques, the MV applicable to a certain sample data region can be predicted based on other MVs, for example, based on the MV related to another sample data region that is spatially adjacent to the region being reconstructed and whose decoding order precedes the MV. This can substantially reduce the amount of data required to encode and decode the MV, thereby eliminating redundancy and enhancing compression. MV prediction can be performed efficiently, for example, because when encoding an input video signal derived from a camera (called natural video), there is a statistical likelihood that multiple regions larger than the region to which a single MV can be applied move in similar directions, so in some cases similar motion vectors derived from multiple MVs of adjacent regions can be used for MV prediction. This results in the MV found for a given region being similar or identical to the MV predicted from the surrounding MVs, and after entropy coding and decoding, it can be represented with fewer bits than the number of bits used to directly code and decode the MV. In some cases, MV prediction can be an example of lossless compression of a signal (i.e., MV) derived from the original signal (i.e., sample stream). In other cases, MV prediction itself can be lossy, for example, because there will be rounding errors when calculating predictors from several surrounding MVs.

[0009] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T H.265 Recommendation, "High Efficiency Video Coding", December 2016). Among the various MV prediction mechanisms provided by H.265, this application describes a technique referred to below as "spatial merging".

[0010] Please refer to Figure 1 , the current block (101) includes samples that have been discovered by the encoder during the motion search process, and the samples can be predicted based on the previous block of the same size that has generated a spatial offset. In addition, the MV can be derived from metadata associated with one or more reference pictures instead of encoding the MV directly. For example, the MV is derived from the metadata of the nearest reference picture (in decoding order) using the MV associated with any of the five surrounding samples A0, A1 and B0, B1, B2 (corresponding to 102 to 106 respectively). In H.265, MV prediction can use the prediction value of the same reference picture that the neighboring blocks are also using. Summary of the invention

[0011] Various aspects of the present disclosure provide methods, devices, readable media, and computer systems for video decoding. In some examples, the device for video decoding includes a processing circuit. The processing circuit can decode a first syntax element from an encoded video code stream. The first syntax element is signaled in a first codec level. The first syntax element indicates a maximum number of merged motion vector prediction MVP candidates. The first codec level is higher than the picture parameter set PPS level. The processing circuit can determine the maximum number of merged MVP candidates based on the first syntax element; the processing circuit can reconstruct a coding block associated with the first codec level based at least on the maximum number of merged MVP candidates.

[0012] In an embodiment, the processing circuit may decode a second syntax element, a third syntax element, and a fourth syntax element from the encoded video bitstream. The second syntax element, the third syntax element, and the fourth syntax element are signaled in the first codec level. The second syntax element indicates the maximum number of geometric merge mode merge candidates. The third syntax element indicates the maximum number of sub-block based merge MVP candidates, and the fourth syntax element indicates the maximum number of intra-block copy IBC merge block vector prediction BVP candidates. The processing circuit may (i) determine the maximum number of the geometric merge mode merge candidates based on the second syntax element, (ii) determine the maximum number of the sub-block based merge MVP candidates based on the third syntax element, and (iii) determine the maximum number of the IBC merge BVP candidates based on the fourth syntax element.

[0013] In an embodiment, the first codec level is a sequence level and the first syntax element is signaled in a sequence parameter set SPS.

[0014] In an embodiment, the processing circuit may decode a second syntax element from the encoded video bitstream based on the condition being satisfied. The second syntax element is signaled in the second codec level. The second syntax element is used to indicate a maximum number of merge candidates for one of the geometric merge mode, the sub-block based merge mode, and the intra block copy (IBC) merge mode.

[0015] In an example, the one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is the geometric merge mode. The maximum number of merge candidates is the maximum number of geometric merge mode merge candidates. The second syntax element indicates the maximum number of the geometric merge mode merge candidates. The condition is that the geometric merge mode is enabled in the second codec level and the maximum number of merge MVP candidates is greater than or equal to 3. The processing circuit may determine the maximum number of the geometric merge mode merge candidates based on the second syntax element.

[0016] In an example, the one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is the sub-block based merge mode. The maximum number of the merge candidates is the maximum number of sub-block based merge MVP candidates. The second syntax element indicates the maximum number of the sub-block based merge MVP candidates. The condition is that affine mode is enabled in the second codec level. The processing circuit may determine the maximum number of the sub-block based merge MVP candidates based on the second syntax element.

[0017] In an example, the processing circuit may modify the second syntax element in a codec level lower than the second codec level.In an example, the first codec level and the second codec level are sequence levels, and the codec level lower than the second codec level is a picture level.

[0018] In an example, the one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is the IBC merge mode. The maximum number of the merge candidates is the maximum number of IBC merge block vector prediction BVP candidates. The second syntax element indicates the maximum number of the IBC merge BVP candidates. The condition is that the IBC merge mode is enabled in the second codec level. The processing circuit can determine the maximum number of the IBC merge BVP candidates based on the second syntax element.

[0019] In an example, the first codec level and the second codec level are sequence levels.

[0020] Aspects of the present disclosure also provide a method for video decoding, including: decoding a first syntax element from an encoded video bitstream, the first syntax element being signaled in a first codec level, the first syntax element indicating a maximum number of merged motion vector prediction MVP candidates, the first codec level being higher than a picture parameter set PPS level; determining the maximum number of merged MVP candidates based on the first syntax element; and reconstructing a coding block associated with the first codec level based at least on the maximum number of merged MVP candidates.

[0021] Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions, which, when executed by a computer for video decoding, cause the computer to perform a method for video decoding.

[0022] Aspects of the present disclosure also provide a computer system, comprising: at least one memory configured to store program code; and at least one processor configured to read the program code and operate according to instructions of the program code to execute the video decoding method. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, properties and various advantages of the disclosed subject matter will become further apparent from the following detailed description and accompanying drawings, in which:

[0024] Figure 1 Schematic diagram of the current block and its surrounding spatial merging candidates in an example.

[0025] Figure 2 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment.

[0026] Figure 3 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment.

[0027] Figure 4 is a schematic diagram of a simplified block diagram of a decoder according to an embodiment.

[0028] Figure 5 is a schematic diagram of a simplified block diagram of an encoder according to an embodiment.

[0029] Figure 6 A block diagram of an encoder according to another embodiment is shown.

[0030] Figure 7 A block diagram of a decoder according to another embodiment is shown.

[0031] Figure 8An exemplary geometric merge mode is shown.

[0032] Fig. 9 An exemplary syntax for signaling in a picture parameter set PPS is shown.

[0033] Fig.10 An exemplary syntax for signaling in a picture header is shown.

[0034] Fig.11 An exemplary syntax for signaling in a sequence parameter set SPS is shown.

[0035] Fig.12 An exemplary syntax for signaling in PPS is shown.

[0036] Fig.13 An exemplary syntax for signaling in a picture header is shown.

[0037] Fig.14 An exemplary syntax for signaling in a picture header is shown.

[0038] Fig.15 An exemplary syntax in a picture header is shown.

[0039] Fig.16 An exemplary syntax in SPS is shown.

[0040] Fig.17 An exemplary syntax in SPS is shown.

[0041] Fig.18A An exemplary syntax in SPS is shown.

[0042] Fig.18B An exemplary syntax in a picture header is shown.

[0043] Fig.19A An exemplary syntax in SPS is shown.

[0044] Fig.19B An exemplary syntax in a picture header is shown.

[0045] Fig. 20 An exemplary syntax in SPS is shown.

[0046] Fig.21 A flow chart outlining a method according to an embodiment of the present disclosure is shown.

[0047] Fig. 22 is a schematic diagram of a computer system according to an embodiment. DETAILED DESCRIPTION

[0048] Figure 22 is a simplified block diagram of a communication system (200) according to an embodiment disclosed in the present application. The communication system (200) includes a plurality of terminal devices, which can communicate with each other through, for example, a network (250). For example, the communication system (200) includes a first terminal device (210) and a second terminal device (220) interconnected through the network (250). Figure 2 In an embodiment of the present invention, the first terminal device (210) and the second terminal device (220) perform unidirectional data transmission. For example, the first terminal device (210) may encode video data (e.g., a video picture stream collected by the terminal device (210)) for transmission to the second terminal device (220) via the network (250). The encoded video data is transmitted in the form of one or more encoded video code streams. The second terminal device (220) may receive the encoded video data from the network (250), decode the encoded video data to restore the video data, and display the video picture based on the restored video data. Unidirectional data transmission is more common in applications such as media services.

[0049] In another embodiment, the communication system (200) includes a third terminal device (230) and a fourth terminal device (240) that perform bidirectional transmission of encoded video data, which can occur, for example, during a video conference. For bidirectional data transmission, each of the third terminal device (230) and the fourth terminal device (240) can encode video data (e.g., a video picture stream collected by the terminal device) to transmit to the other terminal device of the third terminal device (230) and the fourth terminal device (240) through a network (250). Each of the third terminal device (230) and the fourth terminal device (240) can also receive the encoded video data transmitted by the other terminal device of the third terminal device (230) and the fourth terminal device (240), and can decode the encoded video data to restore the video data, and can display the video picture on an accessible display device based on the restored video data.

[0050] exist Figure 2In the embodiment of the present invention, the first terminal device (210), the second terminal device (220), the third terminal device (230) and the fourth terminal device (240) may be servers, personal computers and smart phones, but the principles disclosed in the present application may not be limited thereto. The embodiments disclosed in the present application are applicable to laptop computers, tablet computers, media players and / or dedicated video conferencing equipment. The network (250) represents any number of networks that transmit encoded video data between the first terminal device (210), the second terminal device (220), the third terminal device (230) and the fourth terminal device (240), including, for example, wired (wired) and / or wireless communication networks. The communication network (250) may exchange data in circuit switching and / or packet switching channels. The network may include a telecommunications network, a local area network, a wide area network and / or the Internet. For the purpose of the present application, unless explained below, the architecture and topology of the network (250) may be irrelevant to the operation disclosed in the present application.

[0051] As an example, Figure 3 The video encoder and video decoder are shown in a streaming environment. The subject matter disclosed in this application is equally applicable to other video-enabled applications, including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0052] The streaming system may include an acquisition subsystem (313), which may include a video source (301) such as a digital camera, which creates an uncompressed video picture stream (302). In an embodiment, the video picture stream (302) includes samples taken by a digital camera. Compared to the encoded video data (304) (or the encoded video bitstream), the video picture stream (302) is depicted as a thick line to emphasize the high data volume of the video picture stream, and the video picture stream (302) can be processed by an electronic device (320), which includes a video encoder (303) coupled to the video source (301). The video encoder (303) may include hardware, software, or a combination of hardware and software to implement or implement various aspects of the disclosed subject matter as described in more detail below. Compared to the video picture stream (302), the encoded video data (304) (or the encoded video bitstream (304)) is depicted as a thin line to emphasize the lower amount of data of the encoded video data (304) (or the encoded video bitstream (304)), which can be stored on the streaming server (305) for future use. One or more streaming client subsystems, such as Figure 3The client subsystem (306) and the client subsystem (308) in the video transmission system can access the streaming server (305) to retrieve the copy (307) and the copy (309) of the encoded video data (304). The client subsystem (306) may include, for example, a video decoder (310) in the electronic device (330). The video decoder (310) decodes the incoming copy (307) of the encoded video data and generates an output video picture stream (311) that can be presented on a display (312) (e.g., a display screen) or another presentation device (not depicted). In some streaming transmission systems, the encoded video data (304), the video data (307), and the video data (309) (e.g., a video bitstream) can be encoded according to certain video encoding / compression standards. Examples of these standards include ITU-T H.265. In an embodiment, the video coding standard under development is informally referred to as Versatile Video Coding (VVC), and the present application can be used in the context of the VVC standard.

[0053] It should be noted that the electronic device (320) and the electronic device (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).

[0054] Figure 4 4 is a block diagram of a video decoder (410) according to an embodiment disclosed in the present application. The video decoder (410) may be provided 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 to replace Figure 3 A video decoder (310) of an embodiment.

[0055] The receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410); in the same or another embodiment, one encoded video sequence is received at a time, wherein the decoding of each encoded video sequence is independent of the other encoded video sequences. The encoded video sequence may be received from a channel (401), which may be a hardware / software link to a storage device storing the encoded video data. The receiver (431) may receive the encoded video data as well as other data, such as encoded audio data and / or auxiliary data streams that may be forwarded to their respective consuming entities (not shown). The receiver (431) may separate the encoded video sequence from the other data. To prevent network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder / parser (420) (hereinafter referred to as "parser (420)"). In some applications, the buffer memory (415) is part of the video decoder (410). In other cases, the buffer memory (415) may be provided external to the video decoder (410) (not shown). In other cases, a buffer memory (not shown) is provided outside the video decoder (410) to prevent network jitter, for example, and another buffer memory (415) may be configured inside the video decoder (410) to handle broadcast timing, for example. When the receiver (431) receives data from a storage / forward device with sufficient bandwidth and controllability or from an isochronous network, it may not be necessary to configure the buffer memory (415), or the buffer memory may be made smaller. Of course, in order to use on a service packet network such as the Internet, a buffer memory (415) may also be required, and the buffer memory may be relatively large and have an adaptive size, and may be at least partially implemented in an operating system or a similar element (not shown) outside the video decoder (410).

[0056] The video decoder (410) may include a parser (420) to reconstruct symbols (421) from the encoded video sequence. The types of symbols include information used to manage the operation of the video decoder (410) and potential information used to control a display device such as a display device (412) (e.g., a display screen) that is not part of the electronic device (430) but can be coupled to the electronic device (430), such as Figure 4As shown in . The control information for the display device may be a parameter set fragment (not indicated) of Supplemental Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (420) may parse / entropy decode the received coded video sequence. The encoding of the coded video sequence may be performed 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 sensitivity, and the like. The parser (420) may extract a subgroup parameter set of at least one subgroup of the subgroups of pixels in the video decoder from the coded video sequence based on at least one parameter corresponding to the group. The subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and the like. The parser (420) may also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

[0057] The parser (420) may perform entropy decoding / parsing operations on the video sequence received from the buffer memory (415), thereby creating symbols (421).

[0058] Depending on the type of coded video picture or portion of coded video picture (e.g., inter- and intra-pictures, inter- and intra-blocks) and other factors, the reconstruction of the symbol (421) may involve multiple different units. Which units are involved and how they are involved may be controlled by subgroup control information parsed by the parser (420) from the coded video sequence. For the sake of brevity, such subgroup control information flow between the parser (420) and the multiple units below is not described.

[0059] In addition to the functional blocks already mentioned, the video decoder (410) can be conceptually subdivided into several functional units as described below. In a practical embodiment operating under commercial constraints, many of these units interact closely with each other and can be integrated with each other. However, for the purpose of describing the disclosed subject matter, the conceptual subdivision into the following functional units is appropriate.

[0060] The first unit is a sealer / inverse transform unit (451). The sealer / inverse transform unit (451) receives quantized transform coefficients as symbols (421) from the parser (420) and control information, including which transform method to use, block size, quantization factor, quantization scaling matrix, etc. The sealer / inverse transform unit (451) can output a block including sample values, which can be input into an aggregator (455).

[0061] In some cases, the output samples of the sealer / inverse transform unit (451) may belong to an intra-coded block; that is, a block that does not use predictive information from a previously reconstructed picture, but may use predictive information from a previously reconstructed portion of the current picture. Such predictive information may be provided by an intra-picture prediction unit (452). In some cases, the intra-picture prediction unit (452) generates surrounding blocks of the same size and shape as the block being reconstructed using reconstructed information extracted from the current picture buffer (458). For example, the current picture buffer (458) buffers a partially reconstructed current picture and / or a fully reconstructed current picture. In some cases, the aggregator (455) adds the prediction information generated by the intra-picture prediction unit (452) to the output sample information provided by the sealer / inverse transform unit (451) on a per-sample basis.

[0062] In other cases, the output samples of the scaler / inverse transform unit (451) may belong to an inter-frame coded and potentially motion compensated block. In this case, the motion compensated prediction unit (453) may access the reference picture memory (457) to extract samples for prediction. After the extracted samples are motion compensated according to the symbols (421), these samples may be added to the output of the scaler / inverse transform unit (451) (in this case referred to as residual samples or residual signals) by the aggregator (455) to generate output sample information. The acquisition of the predicted samples by the motion compensated prediction unit (453) from the address in the reference picture memory (457) may be controlled by a motion vector, and the motion vector is provided to the motion compensated prediction unit (453) in the form of the symbols (421), for example, including X, Y and reference picture components. Motion compensation may also include interpolation of sample values ​​extracted from the reference picture memory (457) when using sub-sample accurate motion vectors, motion vector prediction mechanisms, and the like.

[0063] The output samples of the aggregator (455) may be employed by various loop filtering techniques in a loop filter unit (456). The video compression techniques may include in-loop filter techniques controlled by parameters included in the encoded video sequence (also referred to as the encoded video bitstream) and available to the loop filter unit (456) as symbols (421) from the parser (420). However, in other embodiments, the video compression techniques may also be responsive to meta-information obtained during decoding of a previous (in decoding order) portion of an encoded picture or encoded video sequence, as well as to previously reconstructed and loop filtered sample values.

[0064] The output of the loop filter unit (456) may be a sample stream that may be output to a display device (412) and stored in a reference picture memory (457) for subsequent inter-picture prediction.

[0065] Once fully reconstructed, certain coded pictures may be used as reference pictures for future prediction. For example, once the coded picture corresponding to the 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) may become part of the reference picture memory (457), and a new current picture buffer may be reallocated before starting to reconstruct a subsequent coded picture.

[0066] The video decoder (410) may perform decoding operations according to a predetermined video compression technique, such as in the ITU-T H.265 standard. The encoded video sequence may conform to the syntax specified by the video compression technique or standard used in the sense that the encoded video sequence follows the syntax of the video compression technique or standard and the profile recorded in the video compression technique or standard. Specifically, the profile may select certain tools from all the tools available in the video compression technique or standard as the only tools available for use under the profile. For compliance, the complexity of the encoded video sequence is also required to be within the range defined by the hierarchy of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in, for example, mega samples per second), the maximum reference picture size, etc. In some cases, the limits set by the hierarchy may be further limited by the Hypothetical Reference Decoder (HRD) specification and metadata of the HRD buffer management signaled in the encoded video sequence.

[0067] In an embodiment, the receiver (431) may receive additional (redundant) data along with the encoded video. The additional data may be part of the encoded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and / or 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.

[0068] Figure 5 1 is a block diagram of a video encoder (503) according to an embodiment disclosed in the present application. The video encoder (503) is provided in an electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) can be used to replace Figure 3 A video encoder (303) in an embodiment.

[0069] The video encoder (503) can be used to obtain the video source (501) (not Figure 5 In another embodiment, the video source (501) is a part of the electronic device (520) to receive video samples, and the video source can collect video images to be encoded by the video encoder (503). In another embodiment, the video source (501) is a part of the electronic device (520).

[0070] The video source (501) may provide a source video sequence in the form of a digital video sample stream to be encoded by the video encoder (503), wherein the digital video sample stream may have any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, ...), and any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media service system, the video source (501) may be a storage device storing previously prepared videos. 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 a plurality of separate pictures that are given motion when viewed sequentially. The pictures themselves may be constructed as a spatial pixel array, wherein each pixel may include one or more samples depending on the sampling structure, color space, etc. used. The relationship between pixels and samples may be easily understood by those skilled in the art. The following description focuses on the samples.

[0071] According to an embodiment, the video encoder (503) may encode and compress pictures of a source video sequence into an encoded video sequence (543) in real time or under any other time constraints required by the application. Implementing an appropriate encoding speed is a function of the controller (550). In some embodiments, the controller (550) controls other functional units as described below and is functionally coupled to these units. For the sake of simplicity, couplings are not shown in the figure. The parameters set by the controller (550) may include rate control related parameters (picture skipping, quantizer, lambda value of rate distortion optimization technology, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (550) can be used to have other suitable functions that are related to the video encoder (503) optimized for a certain system design.

[0072] In some embodiments, the video encoder (503) operates in a coding loop. As a simple description, in embodiments, the coding loop may include a source encoder (530) (e.g., responsible for creating symbols, such as a symbol stream, based on an input picture to be encoded and a reference picture) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a manner similar to how the (remote) decoder creates sample data (because in the video compression technology considered in this application, any compression between the symbols and the encoded video code stream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (534). Since the decoding of the symbol stream produces bit-accurate results that are independent of the decoder location (local or remote), the contents of the reference picture memory (534) are also bit-accurate between the local encoder and the remote encoder. In other words, the reference picture samples "seen" by the prediction part of the encoder are exactly the same as the sample values ​​that the decoder will "see" when using the prediction during decoding. This basic principle of reference picture synchronization (and the drift that occurs when synchronization cannot be maintained, eg due to channel errors) is also used in some related techniques.

[0073] The operation of the "local" decoder (533) may be combined with, for example, Figure 4 The "remote" decoder described in detail for the video decoder (410) is identical. However, additional brief reference is made to Figure 4 , when symbols are available and the entropy encoder (545) and parser (420) are capable of losslessly encoding / decoding the symbols into an encoded video sequence, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and the parser (420), may not be fully implemented in the local decoder (533).

[0074] At this point, it can be observed that any decoder technology other than the parsing / entropy decoding present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the present application focuses on decoder operation. The description of encoder technology can be simplified because encoder technology is mutually inverse to the decoder technology described comprehensively. A more detailed description is only needed in certain areas and is provided below.

[0075] During operation, in some embodiments, the source encoder (530) may perform motion compensated predictive coding. The motion compensated predictive coding predictively encodes an input picture with reference to one or more previously encoded pictures from a video sequence designated as "reference pictures." In this manner, the encoding engine (532) encodes the differences between pixel blocks of the input picture and pixel blocks of a reference picture that may be selected as a prediction reference for the input picture.

[0076] The local video decoder (533) may decode the encoded video data of the picture that may be designated as the reference picture based on the symbol created by the source encoder (530). The operation of the encoding engine (532) may be a lossy process. When the encoded video data is available at the video decoder ( Figure 5 When the video sequence is decoded at a remote location (not shown), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The local video decoder (533) replicates the decoding process that may be performed by the video decoder on the reference picture and may cause the reconstructed reference picture to be stored in the reference picture cache (534). In this way, the video encoder (503) may locally store a copy of the reconstructed reference picture that has common content (absent transmission errors) with the reconstructed reference picture to be obtained by the remote video decoder.

[0077] The predictor (535) may perform a prediction search for the encoding engine (532). That is, for a new picture to be encoded, the predictor (535) may search the reference picture memory (534) for sample data (as candidate reference pixel blocks) or certain metadata, such as reference picture motion vectors, block shapes, etc., that may serve as appropriate prediction references for the new picture. The predictor (535) may operate pixel-by-pixel based on sample blocks to find a suitable prediction reference. In some cases, based on the search results obtained by the predictor (535), it may be determined that the input picture may have prediction references taken from a plurality of reference pictures stored in the reference picture memory (534).

[0078] The controller (550) may manage encoding operations of the source encoder (530), including, for example, setting parameters and subgroup parameters for encoding video data.

[0079] The outputs of all the above functional units may be entropy encoded in an entropy encoder (545). The entropy encoder (545) performs lossless compression on the symbols generated by the various functional units according to techniques such as Huffman coding, variable length coding, arithmetic coding, etc., thereby converting the symbols into a coded video sequence.

[0080] The transmitter (540) may buffer the encoded video sequence created by the entropy encoder (545) in preparation for transmission over a communication channel (560), which may be a hardware / software link to a storage device where the encoded video data will be stored. The transmitter (540) may combine the encoded video data from the video encoder (503) with other data to be transmitted, such as encoded audio data and / or ancillary data streams (source not shown).

[0081] The controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a certain coded picture type to each coded picture, but this may affect the coding techniques that can be applied to the corresponding picture. For example, a picture may generally be assigned to any of the following picture types:

[0082] An intra picture (I picture) may be a picture that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs allow different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art are aware of the variations of I pictures and their corresponding applications and features.

[0083] A predictive picture (P picture) may be a picture that can be encoded and decoded using intra prediction or inter prediction, which uses at most one motion vector and a reference index to predict sample values ​​for each block.

[0084] Bidirectional predictive pictures (B pictures), which can be pictures that can be encoded and decoded using intra prediction or inter prediction, which uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, multiple predictive pictures can use more than two reference pictures and associated metadata for reconstruction of a single block.

[0085] The source picture may typically be spatially subdivided into blocks of samples (e.g., blocks of 4×4, 8×8, 4×8, or 16×16 samples), and coded block by block. These blocks may be predictively coded with reference to other (already coded) blocks, which are determined according to the coding allocation applied to the block's corresponding picture. For example, blocks of an I picture may be non-predictively coded, or the blocks may be predictively coded (spatial prediction or intra prediction) with reference to already coded blocks of the same picture. Blocks of pixels of a P picture may be predictively coded by spatial prediction with reference to one previously coded reference picture or by temporal prediction. Blocks of a B picture may be predictively coded by spatial prediction with reference to one or two previously coded reference pictures or by temporal prediction.

[0086] The video encoder (503) may perform encoding operations according to a predetermined video encoding technique or standard, such as ITU-T H.265 Recommendation. In operation, the video encoder (503) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancy in an input video sequence. Thus, the encoded video data may conform to the syntax specified by the video encoding technique or standard used.

[0087] In an embodiment, the transmitter (540) may transmit additional data when transmitting the encoded video. The source encoder (530) may include such data as part of the encoded video sequence. The additional data may include other forms of redundant data such as temporal / spatial / SNR enhancement layers, redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0088] The captured video may be taken as a plurality of source pictures (video pictures) in a temporal sequence. Intra-picture prediction (often simplified to intra-prediction) exploits spatial correlations in a given picture, while inter-picture prediction exploits (temporal or other) correlations between pictures. In an embodiment, a particular picture being encoded / decoded is partitioned into blocks, and the particular picture being encoded / decoded is referred to as the current picture. When a block in the current picture is similar to a reference block in a reference picture that was previously encoded in the video and is still buffered, the block in the current picture may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in the case where multiple reference pictures are used, the motion vector may have a third dimension that identifies the reference picture.

[0089] In some embodiments, bidirectional prediction techniques may be used in inter-picture prediction. According to the bidirectional prediction technique, two reference pictures are used, for example, a first reference picture and a second reference picture that are both before the current picture in the video in decoding order (but may be in the past and future in display order, respectively). A block in the current picture may be encoded by a first motion vector pointing to a first reference block in the first reference picture and a second motion vector pointing to a second reference block in the second reference picture. Specifically, the block may be predicted by a combination of the first reference block and the second reference block.

[0090] In addition, merge mode technology can be used in inter-picture prediction to improve coding efficiency.

[0091] According to some embodiments disclosed in the present application, predictions such as inter-picture prediction and intra-picture prediction are performed in blocks. For example, according to the HEVC standard, pictures in a video picture sequence are divided into coding tree units (CTUs) for compression, and the CTUs in the pictures have the same size, such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU includes three coding tree blocks (CTBs), which are a luminance CTB and two chrominance CTBs. Furthermore, each CTU can be split into one or more coding units (CUs) using a quadtree. For example, a 64×64 pixel CTU can be split into a 64×64 pixel CU, or 4 32×32 pixel CUs, or 16 16×16 pixel CUs. In an embodiment, each CU is analyzed to determine the prediction type for the CU, such as an inter-prediction type or an intra-prediction type. In addition, depending on temporal and / or spatial predictability, the CU is split into one or more prediction units (PUs). Typically, each PU includes a luminance prediction block (PB) and two chrominance PBs. In an embodiment, the prediction operation in encoding (encoding / decoding) is performed in units of prediction blocks. Taking the luminance prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values ​​(e.g., luminance values), such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, and the like.

[0092] Figure 6 1 is a diagram of a video encoder (603) according to another embodiment disclosed in the present application. The video encoder (603) is used to receive a processed block (e.g., a prediction block) of sample values ​​in a current video picture in a video picture sequence, and encode the processed block into an encoded picture that is part of an encoded video sequence. In this embodiment, the video encoder (603) is used to replace Figure 3A video encoder (303) in an embodiment.

[0093] In an HEVC embodiment, a video encoder (603) receives a matrix of sample values ​​for a processing block, such as a prediction block of 8×8 samples. The video encoder (603) uses, for example, rate-distortion (RD) optimization to determine whether to use intra mode, inter mode, or bidirectional prediction mode to encode the processing block. When encoding the processing block in intra mode, the video encoder (603) may use intra prediction techniques to encode the processing block into an encoded picture; and when encoding the processing block in inter mode or bidirectional prediction mode, the video encoder (603) may use inter prediction or bidirectional prediction techniques to encode the processing block into an encoded picture, respectively. In some video encoding techniques, the merge mode may be an inter-picture prediction submode, in which a motion vector is derived from one or more motion vector predictors without the aid of an encoded motion vector component external to the predictor. In some other video encoding techniques, there may be a motion vector component applicable to the subject block. In an embodiment, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining the processing block mode.

[0094] exist Figure 6 In an embodiment of the present invention, the video encoder (603) includes: Figure 6 Shown are an inter-frame encoder (630), an intra-frame encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a common controller (621), and an entropy encoder (625) coupled together.

[0095] The inter-frame encoder (630) is used to receive samples of a current block (e.g., a processing block), compare the block with one or more reference blocks in a reference picture (e.g., blocks in a previous picture and a subsequent picture), generate inter-frame prediction information (e.g., redundant information description according to an inter-frame coding technique, motion vectors, merge mode information), and calculate an inter-frame prediction result (e.g., a predicted block) based on the inter-frame prediction information using any suitable technique. In some embodiments, the reference picture is a decoded reference picture decoded based on the encoded video information.

[0096] The intra-frame encoder (622) is used to receive samples of a current block (e.g., a processing block), compare the block with an encoded block in the same picture in some cases, generate quantization coefficients after transformation, and in some cases also generate intra-frame prediction information (e.g., intra-frame prediction direction information according to one or more intra-frame coding techniques). In an embodiment, the intra-frame encoder (622) also calculates an intra-frame prediction result (e.g., a predicted block) based on the intra-frame prediction information and a reference block in the same picture.

[0097] The general controller (621) is used to determine the general control data and control other components of the video encoder (603) based on the general control data. In an embodiment, the general controller (621) determines the mode of the block and provides a control signal to the switch (626) based on the mode. For example, when the mode is intra mode, the general controller (621) controls the switch (626) to select the intra mode result for use by the residual calculator (623) and controls the entropy encoder (625) to select the intra prediction information and add the intra prediction information to the bitstream; and when the mode is inter mode, the general controller (621) controls the switch (626) to select the inter prediction result for use by the residual calculator (623) and controls the entropy encoder (625) to select the inter prediction information and add the inter prediction information to the bitstream.

[0098] The residual calculator (623) is used to calculate the difference (residual data) between the received block and the prediction result selected from the intra-frame encoder (622) or the inter-frame encoder (630). The residual encoder (624) is used to operate based on the residual data to encode the residual data to generate a transform coefficient. In an embodiment, the residual encoder (624) is used to convert the residual data from the spatial domain to the frequency domain and generate a transform coefficient. The transform coefficient is then processed by quantization to obtain a quantized transform coefficient. In various embodiments, the video encoder (603) also includes a residual decoder (628). The residual decoder (628) is used to perform an inverse transform and generate decoded residual data. The decoded residual data can be used appropriately by the intra-frame encoder (622) and the inter-frame encoder (630). For example, the inter-frame encoder (630) can generate a decoded block based on the decoded residual data and the inter-frame prediction information, and the intra-frame encoder (622) can generate a decoded block based on the decoded residual data and the intra-frame prediction information. The decoded blocks are appropriately processed to generate a decoded picture, and in some embodiments, the decoded picture may be buffered in a memory circuit (not shown) and used as a reference picture.

[0099] The entropy encoder (625) is used to format the code stream to produce an encoded block. The entropy encoder (625) generates various information according to a suitable standard such as the HEVC standard. In an embodiment, the entropy encoder (625) is used to obtain general control data, selected prediction information (such as intra-frame prediction information or inter-frame prediction information), residual information, and other suitable information in the code stream. It should be noted that according to the disclosed subject matter, when the block is encoded in the inter-frame mode or the merge sub-mode of the bidirectional prediction mode, there is no residual information.

[0100] Figure 7FIG. 7 is a diagram of a video decoder (710) according to another embodiment disclosed in the present application. The video decoder (710) is used to receive an encoded image as part of an encoded video sequence and decode the encoded image to generate a reconstructed picture. In an embodiment, the video decoder (710) is used to replace Figure 3 A video decoder (310) of an embodiment.

[0101] exist Figure 7 In an embodiment, the video decoder (710) includes Figure 7 An entropy decoder (771), an inter-frame decoder (780), a residual decoder (773), a reconstruction module (774) and an intra-frame decoder (772) coupled together are shown in FIG.

[0102] The entropy decoder (771) may be used to reconstruct certain symbols from the encoded picture, which represent syntax elements constituting the encoded picture. Such symbols may include, for example, a mode for encoding the block (e.g., intra mode, inter mode, bidirectional prediction mode, a merged sub-mode of the latter two, or another sub-mode), prediction information (e.g., intra prediction information or inter prediction information) that may identify certain samples or metadata for prediction by the intra decoder (772) or the inter decoder (780), respectively, residual information in the form of, for example, quantized transform coefficients, and the like. In an embodiment, when the prediction mode is inter or bidirectional 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 be inverse quantized and provided to the residual decoder (773).

[0103] The inter-frame decoder (780) is used for receiving the inter-frame prediction information and generating an inter-frame prediction result based on the inter-frame prediction information.

[0104] The intra-frame decoder (772) is used to receive intra-frame prediction information and generate a prediction result based on the intra-frame prediction information.

[0105] The residual decoder (773) is used to perform inverse quantization to extract dequantized transform coefficients, and process the dequantized transform coefficients to convert the residual from the frequency domain to the spatial domain. The residual decoder (773) may also require some control information (to obtain the quantizer parameter Quantizer Parameter, QP), and the information can be provided by the entropy decoder (771) (the data path is not indicated because this is only low-volume control information).

[0106] The reconstruction module (774) is used to combine the residual output by the residual decoder (773) with the prediction result (which can be output by the inter-frame prediction module or the intra-frame prediction module) in the spatial domain to form a reconstructed block, which can be part of a reconstructed picture, which in turn can be part of a reconstructed video. It should be noted that other suitable operations such as deblocking operations can be performed to improve visual quality.

[0107] It should be noted that the video encoder (303), video encoder (503) and video encoder (603) and video decoder (310), video decoder (410) and video decoder (710) may be implemented using any suitable technology. In an embodiment, the video encoder (303), video encoder (503) and video encoder (603) and video decoder (310), video decoder (410) and video decoder (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (303), video encoder (503) and video encoder (603) and video decoder (310), video decoder (410) and video decoder (710) may be implemented using one or more processors that execute software instructions.

[0108] Various aspects of the present disclosure relate to video coding techniques, such as signaling of the length of various merge candidate lists for various inter-frame prediction codec tools, such as regular merge mode, sub-block based merge mode, intra-block copy (IBC) merge mode, and geometric merge mode (GEO), which are tools outside of HEVC and used in VVC, for example.

[0109] The geometric merging mode (also called geometric partitioning mode) can support a variety of different partitioning methods. Figure 8 An exemplary geometric merge mode is shown. In geometric merge mode, the CU (800) can be partitioned into two partitions, with partition 1 to 2 divided by a line or edge (810). Each of the two partitions can have any suitable shape, such as a triangle, trapezoid, pentagon, etc.

[0110] Merge candidates for inter prediction are valid in video codecs, such as in HEVC and VVC. In an embodiment, for example in VVC, four different merge candidate lists (or merge lists) may exist and be constructed on the encoder and decoder sides. The four merge candidate lists may include a merge candidate list (or first merge candidate) for a conventional merge mode, a merge candidate list (or second merge candidate) for a geometric merge mode, a merge candidate list (or third merge candidate) for a sub-block based merge mode, and a merge candidate list (or fourth merge candidate) for an IBC merge mode.

[0111] Compared with related technologies (such as some technologies in HEVC), the first merge candidate list for the conventional merge mode can be extended to include more types of merge candidates. In addition, the maximum number of merge candidates (or merged motion vector prediction (MVP) candidates) in the first merge candidate list can be extended from 5 to 6, for example. The maximum number of merged MVP candidates in the first merge candidate list can be signaled in the picture parameter set (PPS) at the PPS level or in the picture header at the picture level.

[0112] Fig. 9 A first PPS level parameter (eg, pps_six_minus_max_num_merge_cand_plus1) signaled in the PPS is shown. The first PPS level parameter may indicate the maximum number of merge MVP candidates. Fig.10 A first picture level parameter (eg, pic_six_minus_max_num_merge_cand) signaled in a picture header is shown. The first picture level parameter may indicate the maximum number of merge MVP candidates (MaxNumMergeCand).

[0113] The first syntax element may indicate the maximum number of merge MVP candidates signaled in the corresponding codec level. For example, the first syntax element refers to a first PPS level parameter signaled in the PPS level or a first picture level parameter signaled in the picture level.

[0114] The first PPS level parameter (e.g., pps_six_minus_max_num_merge_cand_plus1) is equal to 0, which may specify that the first picture level parameter (e.g., pic_six_minus_max_num_merge_cand) is present (or signaled) in the picture header of the reference PPS. The first PPS level parameter (e.g., pps_six_minus_max_num_merge_cand_plus1) is greater than 0, which may specify that the first picture level parameter (e.g., pic_six_minus_max_num_merge_cand) is not present (or not signaled) in the picture header of the reference PPS. The value of the first PPS level parameter (e.g., pps_six_minus_max_num_merge_cand_plus1) may be in the range of 0 to 6 (inclusive). When the first PPS level parameter (eg, pps_six_minus_max_num_merge_cand_plus1) is not present, the first PPS level parameter (eg, pps_six_minus_max_num_merge_cand_plus1) may be inferred to be equal to 0.

[0115] The first picture level parameter (eg, pic_six_minus_max_num_merge_cand) subtracted from 6 may specify the maximum number of merge MVP candidates (MaxNumMergeCand) supported in a slice associated with a picture header. The maximum number of merge MVP candidates (MaxNumMergeCand) may be determined using Equation 1.

[0116] MaxNumMergeCand=6-pic_six_minus_max_num_merge_cand (Equation 1)

[0117] The value of MaxNumMergeCand may be in the range of 1 to 6, inclusive. When the first picture level parameter is not present, the value of the first picture level parameter (eg, pic_six_minus_max_num_merge_cand) may be inferred to be equal to the first PPS level parameter (eg, pps_six_minus_max_num_merge_cand_plus1) - 1.

[0118] The geometry merge mode may be enabled or disabled in a sequence level using an SPS syntax element in a sequence parameter set (SPS). In an example, the SPS syntax element is a first sequence level flag (eg, sps_geo_enabled_flag). Fig.11 A first sequence level flag (eg, sps_geo_enabled_flag) signaled in the SPS is shown.

[0119] A first sequence level flag (e.g., sps_geo_enabled_flag) may specify whether motion compensation based on geometric merge mode is used for inter prediction. A first sequence level flag (e.g., sps_geo_enabled_flag) equal to 0 may specify that the syntax should be constrained so that motion compensation based on geometric merge mode is not used in a coded layer video sequence (CLVS), and that syntax elements related to geometric merge mode are not present in the codec syntax of the CLVS. A first sequence level flag (e.g., sps_geo_enabled_flag) equal to 1 may specify that motion compensation based on geometric merge mode is used in CLVS.

[0120] One or more parameters may indicate the maximum number of geometry merge mode merge candidates (MaxNumGeoMergeCand).The one or more parameters may be explicitly signaled in PPS level or picture level.

[0121] Fig.12 An exemplary syntax for signaling in a PPS is shown. The syntax includes a second PPS level parameter (eg, pps_max_num_merge_cand_minus_max_num_geo_cand_plus1) indicating the maximum number of geometric merge mode merge candidates. Fig.13 An exemplary syntax for signaling in a picture header is shown. The syntax includes a second picture level parameter (eg, pic_max_num_merge_cand_minus_max_num_geo_cand) indicating the maximum number of geometric merge mode merge candidates.

[0122] The second syntax element may indicate the maximum number of geometric merge mode merge candidates signaled in the corresponding codec level. For example, the second syntax element refers to a second PPS level parameter signaled in the PPS level, or a second picture level parameter signaled in the picture level.

[0123] The second PPS level parameter (e.g., pps_max_num_merge_cand_minus_max_num_geo_cand_plus1) is equal to 0, which may specify that the second picture level parameter (e.g., pic_max_num_merge_cand_minus_max_num_geo_cand) is present in the picture header of the slice that references the PPS or is signaled in the picture header of the slice that references the PPS. The second PPS level parameter (e.g., pps_max_num_merge_cand_minus_max_num_geo_cand_plus1) is greater than 0, which may specify that the second picture level parameter (e.g., pic_max_num_merge_cand_minus_max_num_geo_cand) is not present in the picture header that references the PPS. The value of the second PPS level parameter (e.g., pps_max_num_merge_cand_minus_max_num_geo_cand_plus1) can be in the range of 0 to MaxNumMergeCand-1. When the second PPS level parameter (eg, pps_max_num_merge_cand_minus_max_num_geo_cand_plus1) is not present, the second PPS level parameter may be inferred to be equal to 0.

[0124] A second picture level parameter (eg, pic_max_num_merge_cand_minus_max_num_geo_cand) that is subtracted from the maximum number of merge MVP candidates (MaxNumMergeCand) may specify the maximum number of geometric merge mode merge candidates supported in the slice associated with the picture header.

[0125] When the second picture level parameter is not present, the first sequence level flag (e.g., sps_geo_enabled_flag) is equal to 1, and the maximum number of merge MVP candidates (MaxNumMergeCand) is greater than or equal to 2, the second picture level parameter (e.g., pic_max_num_merge_cand_minus_max_num_geo_cand) can be inferred to be equal to (second PPS level parameter - 1) (e.g., pps_max_num_merge_cand_minus_max_num_geo_cand_plus1-1).

[0126] The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be determined based on the maximum number of merge MVP candidates (MaxNumMergeCand) and a second picture level parameter (eg, pic_max_num_merge_cand_minus_max_num_geo_cand), for example, using Equation 2.

[0127] MaxNumGeoMergeCand=MaxNumMergeCand-

[0128] pic_max_num_merge_cand_minus_max_num_geo_cand (Equation 2)

[0129] When the second picture level parameter (eg, pic_max_num_merge_cand_minus_max_num_geo_cand) is present (ie, signaled), the value of MaxNumGeoMergeCand may be in the range of 2 to MaxNumMergeCand (inclusive).

[0130] The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be set to equal 0 when the second picture level parameter (e.g., pic_max_num_merge_cand_minus_max_num_geo_cand) is not present (i.e., not signaled) and one of (i) the first sequence level flag (e.g., sps_geo_enabled_flag) is equal to 0 and (ii) the maximum number of merge MVP candidates (MaxNumMergeCand) is less than 2 is satisfied.

[0131] When the maximum number of geometry merge mode merge candidates (MaxNumGeoMergeCand) is equal to 0, geometry merge mode is not allowed for the slice associated with the picture header.

[0132] A second PPS level parameter (e.g., pps_max_num_merge_cand_minus_max_num_geo_cand_plus1), a second picture level parameter (e.g., pic_max_num_merge_cand_minus_max_num_geo_cand), and a maximum number of merge MVP candidates (MaxNumMergeCand) may be used to determine the maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand). The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be specified to not exceed a value of MaxNumMergeCand. For example, the value of MaxNumGeoMergeCand may vary depending on the specific application. When the value of MaxNumGeoMergeCand does not change frequently, PPS signaling may be effective and therefore does not need to be signaled to each picture. On the other hand, when MaxNumGeoMergeCand changes frequently, for example from one picture to another, picture header signaling may be effective.

[0133] Fig.14 An exemplary syntax for signaling in a picture header is shown. The syntax includes a third picture level parameter (e.g., pic_five_minus_max_num_subblock_merge_cand) signaled in the picture header, which indicates the maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) (also referred to as the maximum number of merge candidates for sub-block based merge mode).

[0134] The third syntax element may indicate the maximum number of sub-block based merge MVP candidates signaled in the corresponding codec level.For example, the third syntax element refers to a third picture level parameter signaled in the picture level.

[0135] A third picture level parameter (e.g., pic_five_minus_max_num_subblock_merge_cand) may specify the maximum number of subblock-based merge MVP candidates supported in a slice, subtracted from a value of 5. When the third picture level parameter is not present (or not signaled), the value of the third picture level parameter (e.g., pic_five_minus_max_num_subblock_merge_cand) may be inferred to be equal to (5-(sps_sbtmvp_enabled_flag&& pic_temporal_mvp_enabled_flag)). In an example, sps_sbtmvp_enabled_flag is an SPS level flag. The SPS level flag indicates whether the SBTMVP mode is enabled in the SPS level. In an example, pic_temporal_mvp_enabled_flag is a picture level flag. The picture level flag indicates whether the temporal MVP mode is enabled in the picture level.

[0136] The maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be determined based on a third picture level parameter (eg, pic_five_minus_max_num_subblock_merge_cand), for example, using Equation 3.

[0137] MaxNumSubblockMergeCand=5-pic_five_minus_max_num_subblock_merge_cand

[0138] (Equation 3)

[0139] The value of the maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be in the range of 0 to 5, inclusive.

[0140] Fig.15 An exemplary syntax for signaling in a picture header is shown. The syntax includes a fourth picture level parameter (eg, pic_six_minus_max_num_ibc_merge_cand) indicating the maximum number of IBC merge block vector prediction (BVP) candidates (MaxNumIbcMergeCand) for IBC merge mode.

[0141] The fourth syntax element may indicate the maximum number of IBC merge BVP candidates signaled in the corresponding codec level.For example, the fourth syntax element refers to a fourth picture level parameter signaled in the picture level.

[0142] A fourth picture level parameter (e.g., pic_six_minus_max_num_ibc_merge_cand) subtracted from the value 6 may specify the maximum number of IBC merge BVP candidates supported in a slice associated with the picture header. The maximum number of IBC merge BVP candidates (MaxNumIbcMergeCand) may be determined based on the fourth picture level parameter (e.g., pic_six_minus_max_num_ibc_merge_cand), for example, using Equation 4.

[0143] MaxNumIbcMergeCand=6-pic_six_minus_max_num_ibc_merge_cand (Equation 4)

[0144] The value of the maximum number of IBC merge BVP candidates (MaxNumIbcMergeCand) may be in the range of 1 to 6 (inclusive).

[0145] The syntax element may include a first syntax element, a second syntax element, a third syntax element, a fourth syntax element, etc. As described above, the first syntax element may indicate the maximum number of merge MVP candidates signaled at the corresponding codec level (e.g., a codec level higher than the slice level or the picture level), and thus the first syntax element may indicate the length of the merge MVP candidate list for the normal merge mode. The merge MVP candidate list may include the merge MVP candidates for the normal merge mode. For example, the first syntax element refers to a first PPS level parameter signaled in the PPS level, or a first picture level parameter signaled in the picture level.

[0146] The second syntax element may indicate a maximum number of geometric merge mode merge candidates signaled at a corresponding codec level (e.g., a codec level higher than a slice level or a picture level), and thus the second syntax element may specify a length of a geometric merge mode merge candidate list for the geometric merge mode. The geometric merge mode merge candidate list may include geometric merge mode merge candidates for the geometric merge mode. For example, the second syntax element refers to a second PPS level parameter signaled in a PPS level or a second picture level parameter signaled in a picture level.

[0147] The third syntax element may indicate the maximum number of subblock-based merge MVP candidates signaled at the corresponding codec level (e.g., a codec level higher than the slice level or the picture level), and thus the third syntax element may indicate the length of the subblock-based merge MVP candidate list for the subblock-based merge mode. The subblock-based merge MVP candidate list may include subblock-based merge MVP candidates for the subblock-based merge mode. For example, the third syntax element refers to a third picture-level parameter signaled in the picture level.

[0148] The fourth syntax element may indicate the maximum number of IBC merge BVP candidates signaled in the corresponding codec level (e.g., a codec level higher than the slice level or the picture level), and thus the fourth syntax element may indicate the length of the IBC merge BVP candidate list (or IBC merge candidate list) for the IBC merge mode. The IBC merge BVP candidate list may include the IBC merge BVP candidates for the IBC merge mode. For example, the fourth syntax element refers to a fourth picture level parameter signaled in the picture level.

[0149] According to aspects of the present disclosure, a first syntax element signaled in a first codec level is decoded from an encoded video bitstream. The first syntax element may indicate a maximum number of merged MVP candidates. The first codec level may be any suitable codec level, for example, higher than a slice level. In an example, the first codec level is higher than a PPS level. The maximum number of merged MVP candidates may be determined based on the first syntax element, for example, based on equation 5. Subsequently, a codec block associated with the first codec level may be reconstructed based on at least the maximum number of merged MVP candidates. In an example, the first codec level is a sequence level, and the first syntax element is signaled in an SPS. When the first codec level increases from a lower codec level (e.g., a PPS level) to a higher codec level (e.g., a sequence level), codec efficiency may be increased and signaling overhead may be reduced.

[0150] According to aspects of the present disclosure, one or more of the syntax elements associated with the length of a corresponding merge candidate list (e.g., a merge MVP candidate list, a geometric merge mode merge candidate list, a sub-block based merge MVP candidate list, an IBC merge BVP candidate list, etc.) may be signaled in a first codec level. The first codec level may be any suitable codec level. In an example, the first codec level is higher than a slice level or a picture level. In an example, the first codec level is higher than a PPS level. One or more of the syntax elements may include a first syntax element.

[0151] In an embodiment, one or more of the syntax elements include a first syntax element, a second syntax element, a third syntax element, and a fourth syntax element, and are signaled in an SPS in a sequence level. In an example, the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element are unchanged in a first codec level. In an example, the first codec level is a sequence level. When certain syntax elements (such as one or more of the syntax elements including the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element) are unchanged in a sequence level, signaling certain syntax elements at a sequence level rather than at a lower codec level (e.g., a PPS level, a picture level, or a slice level) can increase codec efficiency and / or reduce signaling overhead.

[0152] In an embodiment, the second syntax element, the third syntax element, and the fourth syntax element may be signaled in the first codec level and may be decoded from the encoded video bitstream. The second syntax element may indicate the maximum number of geometric merge mode merge candidates, the third syntax element may indicate the maximum number of sub-block based merge MVP candidates, and the fourth syntax element may indicate the maximum number of IBC merge BVP candidates. The maximum number of geometric merge mode merge candidates may be determined based on the second syntax element, the maximum number of sub-block based merge MVP candidates may be determined based on the third syntax element, and the maximum number of IBC merge BVP candidates may be determined based on the fourth syntax element.

[0153] Fig.16 Exemplary syntax elements in an SPS are shown. The syntax elements include a first syntax element (eg, six_minus_max_num_merge_cand), a second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand), a third syntax element (eg, five_minus_max_num_subblock_merge_cand), and a fourth syntax element (eg, six_minus_max_num_ibc_merge_cand).

[0154] The first syntax element (eg, six_minus_max_num_merge_cand) subtracted from the value 6 may specify the maximum number of merge MVP candidates supported in the SPS. The maximum number of merge MVP candidates (MaxNumMergeCand) may be determined based on the first syntax element (eg, six_minus_max_num_merge_cand), for example, based on Equation 5.

[0155] MaxNumMergeCand=6-six_minus_max_num_merge_cand (Equation 5)

[0156] The value of MaxNumMergeCand can be in the range of 1 to 6 (inclusive).

[0157] The second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand), subtracted from MaxNumMergeCand, may specify the maximum number of geometric merge mode merge candidates supported in the SPS.

[0158] The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be determined based on the second syntax element and the maximum number of merge MVP candidates, for example using Equation 6.

[0159] MaxNumGeoMergeCand=MaxNumMergeCand

[0160] -max_num_merge_cand_minus_max_num_geo_cand (Equation 6)

[0161] When the second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand) is present (or signaled), the value of the maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be in the range of 2 to the maximum number of merge MVP candidates (MaxNumMergeCand), inclusive.

[0162] The third syntax element (eg, five_minus_max_num_subblock_merge_cand), which is subtracted from the value 5, may specify the maximum number of sub-block based merge MVP candidates supported in the SPS.

[0163] The maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be determined based on the third syntax element (eg, five_minus_max_num_subblock_merge_cand), for example, using Equation 7.

[0164] MaxNumSubblockMergeCand=5-five_minus_max_num_subblock_merge_cand

[0165] (Equation 7)

[0166] The value of MaxNumSubblockMergeCand can be in the range of 0 to 5 (inclusive).

[0167] The fourth syntax element (eg, six_minus_max_num_ibc_merge_cand), which is subtracted from the value 6, may specify the maximum number of IBC merge BVP candidates supported in the SPS. The maximum number of IBC merge BVP candidates (MaxNumIbcMergeCand) may be determined based on the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand), for example using Equation 8.

[0168] MaxNumIbcMergeCand=6-six_minus_max_num_ibc_merge_cand (Equation 8)

[0169] The value of MaxNumIbcMergeCand can be in the range of 0 to 6 (inclusive).

[0170] In an example, syntax elements including a first syntax element, a second syntax element, a third syntax element, and a fourth syntax element are signaled in the PPS. Therefore, the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element may not change within the PPS and may change from the first PPS to the second PPS.

[0171] According to various aspects of the present disclosure, one or more of the syntax elements related to the length of the corresponding merge candidate list may be conditionally signaled, for example, based on whether the corresponding inter-frame prediction codec tool (or inter-frame codec tool) is enabled. In an embodiment, a first syntax element indicating the maximum number of merge MVP candidates (or the length of the merge MVP candidate list for the regular merge mode) is signaled, and the remaining syntax elements related to the length of other merge candidate lists (e.g., the second syntax element, the third syntax element, the fourth syntax element, etc.) may or may not be signaled. Therefore, the enable flag of a specific inter-frame codec tool can be used to control the signaling of the corresponding syntax elements related to the length of the merge candidate list of the specific inter-frame codec tool. Therefore, in some examples, when the enable flag of a specific inter-frame codec tool indicates that the specific inter-frame codec tool is disabled, the corresponding syntax element is not signaled, thereby increasing coding efficiency and / or reducing signaling overhead.

[0172] In an embodiment, the syntax element signaled at the second codec level may be decoded from the encoded video stream based on the condition being satisfied. The syntax element may indicate the maximum number of merge candidates for one of the geometric merge mode, the sub-block based merge mode, the IBC merge mode, etc.

[0173] In an example, one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is the geometric merge mode. The maximum number of merge candidates is the maximum number of geometric merge mode merge candidates. The syntax element is a second syntax element indicating the maximum number of geometric merge mode merge candidates. Fig.17 , if the geometric merge mode is enabled in the second codec level and the maximum number of merge MVP candidates is greater than or equal to 3. The maximum number of geometric merge mode merge candidates may be determined based on the second syntax element.

[0174] In an example, one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is a sub-block based merge mode. The maximum number of merge candidates is the maximum number of sub-block based merge MVP candidates. The syntax element is a third syntax element indicating the maximum number of sub-block based merge MVP candidates. Fig.17 The maximum number of sub-block based merge MVP candidates may be determined based on the third syntax element.

[0175] In an example, one of the geometric merge mode, the sub-block based merge mode, and the IBC merge mode is the IBC merge mode. The maximum number of merge candidates is the maximum number of IBC merge BVP candidates. The syntax element is a fourth syntax element indicating the maximum number of IBC merge BVP candidates. Fig.17 The maximum number of IBC merge BVP candidates may be determined based on the fourth syntax element.

[0176] In an example, a first syntax element indicating the length of the merge MVP candidate list is signaled in the SPS, and a second syntax element indicating the length of the geometric merge mode merge candidate list, a third syntax element indicating the length of the sub-block based merge MVP candidate list, and a fourth syntax element indicating the length of the IBC merge candidate list are signaled, e.g., in Fig.17 The sequence level shown in is conditionally signaled.

[0177] refer to Fig.17, a first syntax element (e.g., six_minus_max_num_merge_cand) is signaled in the SPS. As described above, the first syntax element (e.g., six_minus_max_num_merge_cand) subtracted from the value 6 may specify the maximum number of merge MVP candidates supported in the SPS. The maximum number of merge MVP candidates (MaxNumMergeCand) may be determined based on the first syntax element (e.g., six_minus_max_num_merge_cand), for example, based on Equation 5. The value of MaxNumMergeCand may be in the range of 1 to 6 (inclusive).

[0178] refer to Fig.17 In block (1712), when a first sequence level flag (e.g., sps_geo_enabled_flag) is equal to 1 and the maximum number of merge MVP candidates (MaxNumMergeCand) is greater than or equal to 3, a second syntax element (e.g., max_num_merge_cand_minus_max_num_geo_cand) may be signaled. In an example, the first sequence level flag (e.g., sps_geo_enabled_flag) being equal to 1 indicates that the geometry merge mode is enabled in the sequence level.

[0179] The second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand), subtracted from MaxNumMergeCand, may specify the maximum number of geometric merge mode merge candidates supported in the SPS.

[0180] The maximum number of GEO merge mode candidates (MaxNumGeoMergeCand) can be determined using Equation 6.

[0181] When the second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand) is present, the value of the maximum number of GEO merge mode candidates (MaxNumGeoMergeCand) may be in the range of 2 to the maximum number of merge MVP candidates (MaxNumMergeCand), inclusive.

[0182] When the second syntax element (e.g., max_num_merge_cand_minus_max_num_geo_cand) is not present, the first sequence level flag (e.g., sps_geo_enabled_flag) is equal to 1, and the maximum number of merge MVP candidates (MaxNumMergeCand) is equal to 2, the maximum number of GEO merge mode candidates (MaxNumGeoMergeCand) may be set to 2.

[0183] The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be set to equal 0 when the second syntax element (e.g., max_num_merge_cand_minus_max_num_geo_cand) is not present (or is not signaled) and one of (i) the first sequence level flag (e.g., sps_geo_enabled_flag) is equal to 0 and (ii) the maximum number of merge MVP candidates (MaxNumMergeCand) is less than 2 is satisfied.

[0184] refer to Fig.17 In block (1710), when a second sequence level flag (e.g., sps_affine_enabled_flag) is equal to 1, a third syntax element (e.g., five_minus_max_num_subblock_merge_cand) may be signaled. In an example, the second sequence level flag (e.g., sps_affine_enabled_flag) being equal to 1 indicates that the affine mode is enabled in the sequence level.

[0185] A third syntax element (eg, five_minus_max_num_subblock_merge_cand) subtracted from a value of 5 may specify a maximum number of subblock-based merge MVP candidates supported in the SPS. When the third syntax element is not present, the value of the third syntax element (eg, five_minus_max_num_subblock_merge_cand) may be inferred to be equal to (5-sps_sbtmvp_enabled_flag).

[0186] The maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be determined based on Equation 7.

[0187] The value of MaxNumSubblockMergeCand can be in the range of 0 to 5 (inclusive).

[0188] refer to Fig.17In block (1711), when a third sequence level flag (e.g., sps_ibc_enabled_flag) is equal to 1, a fourth syntax element (e.g., six_minus_max_num_ibc_merge_cand) may be signaled. In an example, the third sequence level flag (e.g., sps_ibc_enabled_flag) being equal to 1 indicates that the IBC merge mode is enabled at the sequence level.

[0189] The fourth syntax element (eg, six_minus_max_num_ibc_merge_cand), which is subtracted from the value 6, may specify the maximum number of IBC merge BVP candidates supported in the SPS. The maximum number of IBC merge BVP candidates (MaxNumIbcMergeCand) may be determined based on the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand), for example using Equation 8.

[0190] When the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand) is not present, MaxNumIbcMergeCand may be equal to 0.

[0191] The value of MaxNumIbcMergeCand can be in the range of 0 to 6 (inclusive).

[0192] In the example, Fig.17 As shown, a first syntax element is signaled in a first codec level (e.g., sequence level), and a second syntax element, a third syntax element, and a fourth syntax element are conditionally signaled in a second codec level (e.g., sequence level). Alternatively, a first syntax element is signaled in a first codec level (e.g., sequence level), and one or more of the following are conditionally signaled in a second codec level (e.g., sequence level): (i) a second syntax element, (ii) a third syntax element, (iii) a fourth syntax element, and / or other syntax elements. The first codec level may be equal to or higher than the second codec level. In an example, the first codec level and the second codec level are sequence levels.

[0193] In an embodiment, a first syntax element indicating the length of the merge MVP candidate list is signaled in a first codec level, and a second syntax element indicating the length of the geometric merge mode merge candidate list, a third syntax element indicating the length of the sub-block based merge MVP candidate list, and a fourth syntax element indicating the length of the IBC merge candidate list are conditionally signaled in the first codec level. In an example, the first codec level is higher than a slice level (or slice header), a picture level (or picture header), etc. In an example, the first codec level is a sequence level.

[0194] Certain syntax elements (e.g., a first syntax element) do not change in a first codec level (e.g., a sequence level) and remain unchanged for pictures, slices, etc. within a sequence. Thus, for example, certain syntax elements may be signaled at a first codec level (e.g., a high codec level) rather than at a codec level lower than the first codec level to improve codec efficiency and / or reduce signaling overhead. Other syntax elements (e.g., a third syntax element) may change at the first codec level and may therefore be signaled at a second codec level (e.g., a low codec level) lower than the first codec level to, for example, increase flexibility. For example, the first codec level is a sequence level, and the third syntax element changes within a sequence but does not change within a picture, and is therefore signaled at a picture level (e.g., a second codec level).

[0195] In an embodiment, a first syntax element indicating the length of the merge MVP candidate list is signaled in a first codec level, and a second syntax element indicating the length of the geometric merge mode merge candidate list and a fourth syntax element indicating the length of the IBC merge candidate list are conditionally signaled in the first codec level. Other syntax elements indicating the length of other merge candidate lists (e.g., a third syntax element indicating the length of the sub-block based merge MVP candidate list) may be signaled in a second codec level lower than the first codec level. In an example, the first codec level is a sequence level, and the second codec level is a PPS level, a picture level, or a slice level.

[0196] In an example, only the first syntax element, the second syntax element, and the fourth syntax element in the sequence level are signaled in the SPS. Other syntax elements indicating the length of other merge candidate lists are signaled at a level lower than the sequence level (e.g., picture level). Other syntax elements may include a third syntax element. In an example, the third syntax element changes within the SPS, for example, from the first picture to the second picture, and thus the third syntax element is signaled in the picture level of each picture in order to have better flexibility.

[0197] Fig.18AIt is shown that the first syntax element, the second syntax element, and the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand) in the sequence level are signaled in the SPS. Fig.18B The third syntax element in the picture level is shown to be signaled in the picture header. FIG. 18A to FIG. 18B The syntax elements shown in may be applied to the following case: the first syntax element (e.g., six_minus_max_num_merge_cand), the second syntax element (e.g., max_num_merge_cand_minus_max_num_geo_cand), and the fourth syntax element do not change in the sequence level, and the third syntax element (e.g., five_minus_max_num_subblock_merge_cand) may change within the sequence.

[0198] In an embodiment, a first syntax element indicating the length of the merge MVP candidate list remains unchanged (e.g., not updated, overwritten, or modified) in a codec level lower than the first codec level. A second syntax element and a fourth syntax element conditionally signaled in a second codec level remain unchanged (e.g., not updated, overwritten, or modified) in a codec level lower than the second codec level. In an example, only the following syntax elements may be updated, overwritten, or modified in a codec level lower than the second codec level: a syntax element indicating the length of other merge candidate lists excluding any one of a merge MVP candidate list, a geometric merge mode merge candidate list, and an IBC merge candidate list. In an example, a third syntax element conditionally signaled in the second codec level is modified in a codec level lower than the second codec level. For example, the third syntax element conditionally signaled at the second codec level (e.g., sequence level) is modified in the picture level.

[0199] In an example, only the third syntax element (which indicates the length of the sub-block based merge candidate list) may be modified, overwritten or updated at a codec level (eg, picture level) lower than the first codec level (eg, sequence level).

[0200] Fig.19A It is shown that the first syntax element, the second syntax element, and the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand) are signaled in the sequence level in the SPS and remain unchanged in the sequence level. FIG. 19A to FIG. 19B It is shown that the third syntax element is signaled in the SPS in the sequence level and may be further modified in the picture header in the picture level. FIG. 19A to FIG. 19BThe syntax elements shown in may be applicable in the following situations: the first syntax element (e.g., six_minus_max_num_merge_cand), the second syntax element (e.g., max_num_merge_cand_minus_max_num_geo_cand), and the fourth syntax element do not change in the sequence level and the third syntax element (e.g., five_minus_max_num_subblock_merge_cand) may be modified from one picture to another.

[0201] When the third syntax element (eg, five_minus_max_num_subblock_merge_cand) is not present in the SPS, and pic_temporal_mvp_enabled_flag and sps_sbtmvp_enabled_flag are both equal to 1, the maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be equal to 1 for the slice associated with the current picture header.

[0202] According to aspects of the present disclosure, when one or more of the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element are signaled at a first codec level (e.g., a sequence level), for example, higher than a slice level or a picture level, one or more of the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element cannot be updated, overwritten, or modified in a codec level (e.g., a PPS level, a picture level, or a slice level) lower than the first codec level (e.g., a sequence level).

[0203] In an example, the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element are signaled in the SPS in a sequence level, and the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element cannot be updated, overwritten, or modified in a codec level (e.g., a PPS level, a picture level, or a slice level) lower than the sequence level.

[0204] In an example, the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element are signaled in the PPS at the PPS level, and the first syntax element, the second syntax element, the third syntax element, and the fourth syntax element cannot be updated, overwritten, or modified in a codec level (e.g., a picture level or a slice level) lower than the PPS level.

[0205] According to aspects of the present disclosure, additional syntax elements may be used to further indicate the presence of one or more syntax elements related to the lengths of various merge candidate lists.

[0206] In the example, Fig. 20 The syntax element or flag (e.g., six_minus_max_num_ibc_merge_cand_present flag) indicating the presence of a fourth syntax element related to the length of the IBC merge BVP candidate list as indicated by the box (2010) in the table is used to further indicate whether the fourth syntax element exists, such as Fig. 20 As shown in . Therefore, in addition to the third sequence level flag (e.g., sps_ibc_enabled_flag), the presence of the fourth syntax element is conditionally determined based on the syntax element (e.g., the six_minus_max_num_ibc_merge_cand_present flag). The fourth syntax element is conditionally signaled based on the syntax element (e.g., the six_minus_max_num_ibc_merge_cand_present flag) and the third sequence level flag (e.g., sps_ibc_enabled_flag). The above description can be appropriately adjusted to apply to the signaling of other syntax elements, such as the second syntax element, the third syntax element, etc.

[0207] The first syntax element (e.g., six_minus_max_num_merge_cand) subtracted from the value 6 may specify the maximum number of merge MVP candidates supported in the SPS. The maximum number of merge MVP candidates (MaxNumMergeCand) may be determined based on Equation 5 as described above. The value of MaxNumMergeCand may be in the range of 1 to 6, inclusive.

[0208] The second syntax element (eg, max_num_merge_cand_minus_max_num_geo_cand), subtracted from MaxNumMergeCand, may specify the maximum number of geometric merge mode merge candidates supported in the SPS.

[0209] The maximum number of geometric merge mode merge candidates (MaxNumGeoMergeCand) may be determined based on Equation 6 as described above.

[0210] When max_num_merge_cand_minus_max_num_geo_cand is present, the value of MaxNumGeoMergeCand may be in the range of 2 to MaxNumMergeCand (inclusive).

[0211] When max_num_merge_cand_minus_max_num_geo_cand is not present, and sps_geo_enabled_flag is equal to 1 and MaxNumMergeCand is equal to 2, MaxNumGeoMergeCand is set equal to 2.

[0212] When max_num_merge_cand_minus_max_num_geo_cand does not exist and (sps_geo_enabled_flag is equal to 0 or MaxNumMergeCand is less than 2), MaxNumGeoMergeCand is set equal to 0.

[0213] A third syntax element (eg, five_minus_max_num_subblock_merge_cand) subtracted from the value 5 may specify the maximum number of subblock-based merge MVP candidates supported in the SPS. When the third syntax element is not present, the value of five_minus_max_num_subblock_merge_cand may be inferred to be equal to (5-sps_sbtmvp_enabled_flag).

[0214] The maximum number of sub-block based merge MVP candidates (MaxNumSubblockMergeCand) may be determined based on Equation 7.

[0215] The value of MaxNumSubblockMergeCand can be in the range of 0 to 5 (inclusive).

[0216] The syntax element six_minus_max_num_ibc_merge_cand_present flag may specify the presence of a maximum number of IBC merge BVP candidates. When the six_minus_max_num_ibc_merge_cand_present flag is not present, the six_minus_max_num_ibc_merge_cand_present flag may be inferred to be 0. When the six_minus_max_num_ibc_merge_cand_present flag is present, a fourth syntax element (eg, six_minus_max_num_ibc_merge_cand) is present in the codestream.

[0217] The fourth syntax element (eg, six_minus_max_num_ibc_merge_cand), which is subtracted from the value 6, may specify the maximum number of IBC merge BVP candidates supported in the SPS. The maximum number of IBC merge BVP candidates (MaxNumIbcMergeCand) may be determined using Equation 8.

[0218] When the fourth syntax element (eg, six_minus_max_num_ibc_merge_cand) is not present, MaxNumIbcMergeCand may be equal to 0.

[0219] The value of MaxNumIbcMergeCand can be in the range of 1 to 6 (inclusive).

[0220] Fig.21 A flowchart outlining a method (2100) according to an embodiment of the present disclosure is shown. The method (2100) may be used to signal various syntax elements indicating a maximum number of merge candidates, such as a maximum number of merge MVP candidates, a maximum number of geometric merge mode merge candidates, a maximum number of sub-block based merge MVP candidates, a maximum number of IBC merge BVP candidates, and the like. In various embodiments, the method (2100) is performed by a processing circuit, such as a processing circuit in a terminal device (210), (220), (230), and (240), a processing circuit that performs the functions of a video encoder (303), a processing circuit that performs the functions of a video decoder (310), a processing circuit that performs the functions of a video decoder (410), a processing circuit that performs the functions of a video encoder (503), and the like. In some embodiments, the method (2100) is implemented in software instructions, so that when the processing circuit executes the software instructions, the processing circuit performs the method (2100). The method starts at (S2101) and proceeds to (S2110).

[0221] At (S2110), a first syntax element is decoded from the encoded video bitstream, and the first syntax element is signaled in a first codec level. The first syntax element indicates a maximum number of merged motion vector prediction MVP candidates. The first codec level is higher than the picture parameter set PPS level. In the example, the first codec level is a sequence level.

[0222] At (S2120), the maximum number of the merge MVP candidates is determined based on the first syntax element.

[0223] At (S2130), based at least on the maximum number of merged MVP candidates, a coding block associated with the first coding level is reconstructed. The method (2100) proceeds to (S2199) and terminates.

[0224] The method (2100) may be modified as appropriate. Steps in the method (2100) may be modified and / or omitted. Additional steps may be added. Any suitable implementation order may be used.

[0225] In some examples, additional syntax elements such as one or more of the second syntax element, the third syntax element, and the fourth syntax element may be signaled or conditionally signaled. Thus, the maximum number of geometric merge mode merge candidates may be determined based on the second syntax element, the maximum number of sub-block based merge MVP candidates may be determined based on the third syntax element, and the maximum number of IBC merge BVP candidates may be determined based on the fourth syntax element.

[0226] The embodiments in the present disclosure may be used alone or in any order. In addition, each of the method (or embodiment), encoder and decoder may be implemented by a processing circuit (e.g., one or more processors or one or more integrated circuits). In one example, one or more processors execute a program stored in a non-volatile computer-readable medium. As described above, the method (or embodiment), encoder and decoder in the present disclosure may increase encoding and decoding efficiency and / or reduce signaling overhead.

[0227] The above techniques may be implemented as computer software via computer-readable instructions and physically stored in one or more computer-readable media. Fig. 22 A computer system (2200) is shown that is suitable for implementing certain embodiments of the disclosed subject matter.

[0228] The computer software may be encoded in any suitable machine code or computer language, and may be assembled, compiled, linked, or the like to create a code comprising instructions, which may be directly executed by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or executed by decoding, microcode, or the like.

[0229] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablets, servers, smartphones, gaming devices, IoT devices, etc.

[0230] Fig. 22 The components shown for the computer system (2200) are exemplary in nature and are not intended to limit the scope of use or functionality of the computer software implementing the embodiments of the present application. The configuration of the components should not be interpreted as having any dependency or requirement on any component or combination of components shown in the exemplary embodiment of the computer system (2200).

[0231] The computer system (2200) may include certain human-computer interface input devices. Such human-computer interface input devices may respond to input from one or more human users through tactile input (e.g., keyboard input, sliding, data glove movement), audio input (e.g., sound, applause), visual input (e.g., gestures), and olfactory input (not shown). The human-computer interface devices may also be used to capture certain media that are not necessarily directly related to human conscious input, such as audio (e.g., speech, music, ambient sound), images (e.g., scanned images, photographic images obtained from a still image camera), and videos (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0232] The human-computer interface input device may include one or more of the following (only one of which is drawn): keyboard (2201), mouse (2202), touchpad (2203), touch screen (2210), data gloves (not shown), joystick (2205), microphone (2206), scanner (2207), camera (2208).

[0233] The computer system (2200) may also include certain human-computer interface output devices. Such human-computer interface output devices may stimulate the senses of one or more human users through, for example, tactile output, sound, light, and smell / taste. Such human-computer interface output devices may include tactile output devices (e.g., tactile feedback through a touch screen (2210), a data glove (not shown), or a joystick (2205), but there may also be tactile feedback devices that are not used as input devices), audio output devices (e.g., speakers (2209), headphones (not shown)), visual output devices (e.g., screens (2210) including cathode ray tube screens, liquid crystal screens, plasma screens, organic light emitting diode screens, each of which has or does not have a touch screen input function, each of which has or does not have a tactile feedback function - some of which can output two-dimensional visual output or output of more than three dimensions by means such as stereoscopic picture output; virtual reality glasses (not shown), holographic displays, and smoke boxes (not shown)) and printers (not shown).

[0234] The computer system (2200) may also include human-accessible storage devices and their associated media, such as optical media including high-density read-only / rewritable optical disks (CD / DVD ROM / RW) (2220) with CD / DVD or similar media (2221), thumb drives (2222), removable hard disk drives or solid state drives (2223), traditional magnetic media such as tapes and floppy disks (not shown), special-purpose ROM / ASIC / PLD-based devices such as security software protectors (not shown), and the like.

[0235] Those skilled in the art should also understand that the term "computer-readable media" used in connection with the disclosed subject matter does not include transmission media, carrier waves, or other transient signals.

[0236] The computer system (2200) may also include an interface to one or more communication networks. For example, the network may be wireless, wired, or optical. The network may also be a local area network, a wide area network, a metropolitan area network, an in-vehicle network, an industrial network, a real-time network, a delay-tolerant network, and the like. The network also includes local area networks such as Ethernet, wireless local area networks, cellular networks (GSM, 3G, 4G, 5G, LTE, etc.), television wired or wireless wide area digital networks (including cable television, satellite television, and terrestrial broadcast television), in-vehicle and industrial networks (including CANBus), and the like. Some networks typically require an external network interface adapter for connecting to some universal data ports or peripheral buses (2249) (e.g., a USB port of the computer system (2200)); other systems are typically integrated into the core of the computer system (2200) by connecting to the system bus as described below (e.g., an Ethernet interface integrated into a PC computer system or a cellular network interface integrated into a smart phone computer system). By using any of these networks, the computer system (2200) can communicate with other entities. The communication can be one-way, for receiving only (e.g., wireless television), one-way for sending only (e.g., CAN bus to certain CAN bus devices), or two-way, such as to other computer systems via a local or wide area digital network. Each of the above networks and network interfaces can use certain protocols and protocol stacks.

[0237] The above-mentioned human-machine interface devices, human-accessible storage devices, and network interfaces may be connected to the core (2240) of the computer system (2200).

[0238] The core (2240) may include one or more central processing units (CPUs) (2241), graphics processing units (GPUs) (2242), dedicated programmable processing units in the form of field programmable gate arrays (FPGAs) (2243), hardware accelerators for specific tasks (2244), etc. These devices, as well as read-only memory (ROM) (2245), random access memory (2246), internal mass storage (e.g., internal non-user accessible hard disk drives, solid-state drives, etc.) (2247), etc., may be connected via a system bus (2248). In some computer systems, the system bus (2248) may be accessed in the form of one or more physical plugs so that it may be expanded by additional central processing units, graphics processing units, etc. Peripheral devices may be directly attached to the core's system bus (2248), or connected via a peripheral bus (2249). The architecture of the peripheral bus includes PCI, USB, etc.

[0239] The CPU (2241), GPU (2242), FPGA (2243) and accelerator (2244) can execute certain instructions, which can be combined to form the above-mentioned computer code. The computer code can be stored in ROM (2245) or RAM (2246). Transition data can also be stored in RAM (2246), while permanent data can be stored in, for example, internal mass storage (2247). Fast storage and retrieval of any memory device can be achieved by using a cache memory, which can be closely associated with one or more CPUs (2241), GPUs (2242), mass storage (2247), ROM (2245), RAM (2246), etc.

[0240] The computer readable medium may have computer code thereon for performing various computer-implemented operations. The medium and computer code may be specially designed and constructed for the purpose of this application, or may be medium and code well known and available to those skilled in the art of computer software.

[0241] As an example and not a limitation, a computer system having an architecture (2200), in particular a core (2240), can provide the function of executing software contained in one or more tangible computer-readable media as a processor (including a CPU, a GPU, an FPGA, an accelerator, etc.). Such a computer-readable medium can be a medium associated with the above-mentioned user-accessible mass storage, as well as a specific memory of the core (2240) having non-volatility, such as a core internal mass storage (2247) or a ROM (2245). Software implementing various embodiments of the present application can be stored in such a device and executed by the core (2240). Depending on specific needs, the computer-readable medium may include one or more storage devices or chips. The software can enable the core (2240), in particular the processor therein (including a CPU, a GPU, an FPGA, etc.) to perform a specific process or a specific part of a specific process described herein, including defining a data structure stored in the RAM (2246) and modifying such a data structure according to a software-defined process. Additionally or alternatively, the computer system may provide functionality hardwired in logic or otherwise contained in circuitry (e.g., accelerator (2244)) that may operate in place of or in conjunction with software to perform a particular process or a particular portion of a particular process described herein. Where appropriate, references to software may include logic and vice versa. Where appropriate, references to computer-readable media may include circuitry (e.g., an integrated circuit (IC)) storing the executing software, circuitry containing the executing logic, or both. The present application includes any suitable combination of hardware and software.

[0242] Appendix A: Acronyms

[0243] JEM: Joint Exploration Model

[0244] VVC: versatile video coding

[0245] BMS: Benchmark set

[0246] MV: Motion Vector

[0247] HEVC: High Efficiency Video Coding

[0248] SEI: Supplementary Enhancement Information

[0249] VUI: Video Usability Information

[0250] GOPs: Groups of Pictures

[0251] TUs: Transform Units

[0252] PUs: Prediction Units

[0253] CTUs: Coding Tree Units

[0254] CTBs: Coding Tree Blocks

[0255] PBs: Prediction Blocks

[0256] HRD: Hypothetical Reference Decoder

[0257] SNR: Signal Noise Ratio

[0258] CPUs: Central Processing Units

[0259] GPUs: Graphics Processing Units

[0260] CRT: Cathode Ray Tube

[0261] LCD: Liquid-Crystal Display

[0262] OLED: Organic Light-Emitting Diode

[0263] CD: Compact Disc

[0264] DVD: Digital Video Disc

[0265] ROM: Read-Only Memory

[0266] RAM: Random Access Memory

[0267] ASIC: Application-Specific Integrated Circuit

[0268] PLD: Programmable Logic Device

[0269] LAN: Local Area Network

[0270] GSM: Global System for Mobile communications

[0271] LTE: Long-Term Evolution

[0272] CANBus: Controller Area Network Bus

[0273] USB: Universal Serial Bus

[0274] PCI: Peripheral Component Interconnect

[0275] FPGA: Field Programmable Gate Areas

[0276] SSD: solid-state drive

[0277] IC:Integrated Circuit

[0278] CU: Coding Unit

[0279] Although the present application has described a number of exemplary embodiments, various changes, arrangements and various equivalent substitutions of the embodiments are within the scope of the present application. Therefore, it should be understood that those skilled in the art can design a variety of systems and methods, which, although not explicitly shown or described herein, embody the principles of the present application and are therefore within the spirit and scope of the present application.

Claims

1. A video encoding method, characterized in that: include: Generate a first syntax element, the first syntax element indicating a maximum number of merged motion vector prediction MVP candidates; Encoding the first syntax element at a first codec level in an encoded video bitstream, the first codec level being higher than a picture parameter set PPS level; as well as Sending the encoded video code stream including the first syntax element; The maximum number of merged MVP candidates indicated by the first syntax element is applicable to reconstructing coding blocks of the coded video code stream associated with the first coding level.

2. The method according to claim 1, wherein: The encoded video code stream further includes: a second syntax element, a third syntax element and a fourth syntax element signaled in the first codec level, wherein the second syntax element indicates the maximum number of geometric merge mode merge candidates, the third syntax element indicates the maximum number of sub-block based merge MVP candidates, and the fourth syntax element indicates the maximum number of intra block copy IBC merge block vector prediction BVP candidates.

3. The method according to claim 1, wherein: The first coding level is a sequence level, and the first syntax element is encoded in a sequence parameter set SPS.

4. The method according to claim 1, wherein: Based on the satisfied condition, the encoded video code stream further includes: a second syntax element of a second codec level, the second syntax element indicating a maximum number of merge candidates of one of a geometric merge mode, a sub-block based merge mode and an intra block copy (IBC) merge mode.

5. The method according to claim 4, wherein: The one of the geometric merge mode, the sub-block based merge mode and the IBC merge mode is the geometric merge mode; The maximum number of merge candidates is the maximum number of merge candidates in geometric merge mode; The second syntax element indicates the maximum number of merging candidates for the geometric merging mode; and The condition is: the geometric merge mode is enabled in the second codec level, and the maximum number of merged MVP candidates is greater than or equal to 3.

6. The method according to claim 4, wherein: The one of the geometric merge mode, the sub-block based merge mode and the IBC merge mode is a sub-block based merge mode; The maximum number of merge candidates is a maximum number of merge MVP candidates based on sub-blocks; The second syntax element indicates the maximum number of the sub-block based merge MVP candidates; and The condition is: enabling affine mode in the second codec level.

7. The method according to claim 4, wherein: The one of the geometric merge mode, the sub-block based merge mode and the IBC merge mode is the IBC merge mode; The maximum number of merge candidates is the maximum number of IBC merged BVP candidates; The second syntax element indicates the maximum number of IBC merged BVP candidates; and The condition is: enabling the IBC merge mode in the second codec level.

8. The method according to claim 4, wherein: The first codec level and the second codec level are sequence levels.

9. The method according to claim 6, wherein: The second syntax element is modified in a codec level lower than the second codec level.

10. The method according to claim 9, wherein: The first codec level and the second codec level are sequence levels, and a codec level lower than the second codec level is a picture level.

11. A method for video decoding, characterized in that: include: Decoding a first syntax element from an encoded video bitstream, the first syntax element being signaled at a first codec level, the first syntax element indicating a maximum number of merged motion vector prediction (MVP) candidates; determining the maximum number of the merged MVP candidates based on the first syntax element; as well as Based at least on the maximum number of merged MVP candidates, coding blocks of the coded video stream associated with the first codec level are reconstructed.

12. A video encoding device, characterized in that: The method comprises a processing circuit configured to execute the method according to any one of claims 1 to 10.

13. A device for video decoding, characterized in that: The method comprises a processing circuit configured to perform the method of claim 11.

14. A method for processing a video code stream, characterized in that: The video code stream is stored on a non-volatile computer-readable storage medium and decoded according to the method of claim 11, or the video code stream is generated according to the method of any one of claims 1-10.

15. A non-volatile computer-readable medium storing instructions, characterized in that: When the instructions are executed by a computer for video encoding and decoding, the computer is caused to execute: the method according to any one of claims 1-11.

16. A computer system, characterized in that: The computer system comprises: at least one memory configured to store program code; and At least one processor is configured to read the program code and operate according to instructions of the program code to execute the method according to any one of claims 1 to 11.

Images