Adaptive motion vectors for warping motion modes of video coding

Abstract

Various embodiments described herein include methods and systems for coding video. In one aspect, the method includes receiving a video bitstream including a current coding block in a current image frame, obtaining a syntax element value, and determining, based on the syntax element value, whether the current coding block is coded in a warped motion mode or a translation motion mode. The method further includes selecting a first motion vector differential (MVD) setting for the current coding block in accordance with a determination that the current coding block is coded in the warped motion mode, selecting a second MVD setting different from the second MVD setting for the current coding block in accordance with a determination that the current coding block is coded in the translation motion mode, and reconstructing the current coding block based at least in part on the selected MVD setting for the current coding block.

Description

[Technical Field]

[0001] Related Applications This application is a continuation of and claims priority to U.S. patent application Ser. No. 18 / 195,888, filed May 10, 2023, entitled "Adaptive Motion Vector for Warped Motion Mode of Video Coding," and claims priority to U.S. provisional patent application Ser. No. 63 / 390,551, filed July 19, 2022, entitled "Adaptive Motion Vector for Warped Motion Mode of Video Coding," which is incorporated herein by reference in its entirety.

[0002] The disclosed embodiments relate generally to video coding, including, but not limited to, systems and methods for dynamically adjusting motion vector differential settings (e.g., accuracy limits, magnitude ranges) for different motion compensation modes in inter-prediction of video data. [Background technology]

[0003] Digital video is supported by a variety of electronic devices, such as digital televisions, laptop or desktop computers, tablet computers, digital cameras, digital recording devices, digital media players, video game consoles, smartphones, video teleconferencing devices, video streaming devices, etc. The electronic devices send, receive, or communicate digital video data over communication networks and / or store the digital video data on storage devices. Because communication networks have limited bandwidth capacity and storage devices have limited memory resources, video coding may be used to compress the video data according to one or more video coding standards before the video data is communicated or stored.

[0004] Multiple video codec standards have been developed. For example, video coding standards include AOMedia Video 1 (AV1), Versatile Video Coding (VVC), Joint Exploration test Model (JEM), High-Efficiency Video Coding (HEVC / H.265), Advanced Video Coding (AVC / H.264), and Moving Picture Expert Group (MPEG) coding. Video coding generally utilizes prediction methods (e.g., inter-prediction, intra-prediction, etc.) that exploit the redundancy inherent in video data. Video coding aims to compress video data into a format that uses a lower bitrate while avoiding or minimizing degradation of video quality.

[0005] HEVC, also known as H.265, is a video compression standard designed as part of the MPEG-H project. ITU-T and ISO / IEC published the HEVC / H.265 standard in 2013 (Version 1), 2014 (Version 2), 2015 (Version 3), and 2016 (Version 4). Versatile Video Coding (VVC), also known as H.266, is a video compression standard intended as the successor to HEVC. ITU-T and ISO / IEC published the VVC / H.266 standard in 2020 (Version 1) and 2022 (Version 2). AV1 is an open video coding format designed as a replacement for HEVC. The effective version 1.0.0 of this specification, including Errata 1, was released on January 8, 2019. Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, encoding (compression) reduces bandwidth and / or storage space requirements. As will be discussed in more detail below, both lossless and lossy compression can be employed. Lossless compression refers to techniques in which an exact replica of the original signal can be reconstructed from the compressed original signal through a decoding process. Lossy compression refers to a coding / decoding process in which the original video information is not fully preserved during coding and cannot be fully restored during decoding. When using lossy compression, the reconstructed signal may not be identical to the original signal, but the distortion between the original and reconstructed signal is small enough to make the reconstructed signal useful for its intended use. The amount of tolerable distortion depends on the application. For example, users of certain consumer video streaming applications may tolerate higher distortion than users of film or television broadcast applications. The compression ratio achievable by a particular coding algorithm can be selected or adjusted to reflect various distortion tolerances; i.e., higher distortion tolerance generally allows for coding algorithms that result in higher loss and higher compression ratios.

[0007] This disclosure describes dynamically adjusting motion vector difference (MVD) settings (e.g., accuracy limit, magnitude range) for different motion compensation modes in inter-prediction of video data. For example, motion compensation modes include warped motion mode and translational motion mode. In translational motion mode, a current coding block of a current frame is associated with a reference block of a reference frame through translational motion. In warped motion mode, a current coding block of a current frame is associated with a reference block of a reference frame through warping motion, which includes motion such as translation, scaling, and / or rotation. Adaptive MVD accuracy is applied to both translational motion and warped motion. In some embodiments, the allowed MVD magnitudes are the same for these two modes; however, considering the different characteristics of warped motion and translational motion, it is not optimal to share the same set of MVD magnitudes between these two modes. In various embodiments of the present application, MVD settings (e.g., accuracy limit, magnitude range) are customized and optimized for warped motion mode and translational motion mode in inter-prediction of video data. [Means for solving the problem]

[0008] According to some embodiments, a method of video coding is provided. The method includes receiving a video bitstream including a current coding block in a current image frame and obtaining a syntax element value associated with the current coding block in the current image frame. The syntax element value is signaled before a motion vector differential (MVD) associated with the current coding block. The syntax element value indicates whether the current coding block is coded in a warped motion mode. The method further includes determining whether the current coding block is coded in a warped motion mode or a translation motion mode based on the syntax element value. The method further includes selecting a first MVD setting for the current coding block according to a determination that the current coding block is coded in the warped motion mode. The method further includes selecting a second MVD setting for the current coding block according to a determination that the current coding block is coded in the translation motion mode. The second MVD setting is different from the second MVD setting. The method further includes reconstructing the current coding block based at least in part on the selected MVD setting for the current coding block.

[0009] In some embodiments, the first MVD setting includes a first MVD accuracy limit and the second MVD setting includes a second MVD accuracy limit. The first MVD accuracy limit is lower than the second MVD accuracy limit. In some embodiments, the first MVD setting further includes a first MVD magnitude range and the second MVD setting includes a second MVD magnitude range. The first MVD magnitude range is different from the second MVD magnitude range.

[0010] According to some embodiments, a computing system, such as a streaming system, a server system, a personal computer system, or other electronic device, is provided. The computing system includes control circuitry and a memory that stores one or more instruction sets. The one or more instruction sets include instructions for performing any of the methods described herein. In some embodiments, the computing system includes an encoder component and / or a decoder component.

[0011] According to some embodiments, a non-transitory computer-readable storage medium is provided that stores one or more instruction sets for execution by a computing system, the one or more instruction sets including instructions for performing any of the methods described herein.

[0012] Accordingly, disclosed are devices and systems having methods for coding video, which may complement or replace conventional methods, devices, and systems for video coding.

[0013] The features and advantages described herein are not necessarily all-inclusive, and in particular, some additional features and advantages will be apparent to those skilled in the art upon consideration of the drawings, specification, and claims provided in this disclosure. Furthermore, it should be noted that the language used herein has been chosen primarily for purposes of readability and explanation, and not necessarily to describe or limit the subject matter described herein.

[0014] In order that the present disclosure may be more fully understood, a more particular description may be made by reference to features of various embodiments, some of which are shown in the accompanying drawings. However, the accompanying drawings merely illustrate relevant features of the present disclosure and therefore should not be considered necessarily limiting, as the description may recognize other useful features as understood by those skilled in the art upon reading the present disclosure. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram illustrating an exemplary communication system according to some embodiments. [Figure 2A] FIG. 2 is a block diagram illustrating exemplary elements of an encoder component according to some embodiments. [Figure 2B] FIG. 2 is a block diagram illustrating exemplary elements of a decoder component according to some embodiments. [Figure 3] FIG. 1 is a block diagram illustrating an exemplary server system according to some embodiments. [Figure 4A] 1 is a schematic diagram of an inter-predictive coding structure that associates a current coding block with a reference block, according to some embodiments. [Figure 4B] FIG. 1 is a schematic diagram of an inter-predictive coding configuration in which the MVD is identified within a region of a reference frame, according to some embodiments. [Figure 5] 1 is a schematic diagram of a bilateral matching arrangement that associates a current coding block in a GOP with two reference blocks located in the same GOP based on two different motion vectors, according to some embodiments. [Figure 6A] FIG. 1 is a schematic diagram of a bilateral matching arrangement in which the MVD of a reference block is refined, according to some embodiments. [Figure 6B] FIG. 1 is a schematic diagram of a bilateral matching configuration in which the MVD of a reference block is refined within an MVD refinement range, according to some embodiments. [Figure 7] 1 is a flow diagram illustrating a method for coding video according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0016] According to common practice, the various features illustrated in the drawings are not necessarily drawn to scale and like reference numerals may be used to denote like features throughout the specification and drawings.

[0017] This disclosure describes dynamically adjusting motion vector differential (MVD) settings (e.g., accuracy limit, magnitude range) for different motion compensation modes in inter-prediction of video data. For example, motion compensation modes include warping motion mode and translation motion mode. In translation motion mode, a current coding block of a current frame is associated with a reference block of a reference frame via translation motion. In warping motion mode, a current coding block of a current frame is associated with a reference block of a reference frame via warping motion, which may include, for example, translation, scaling, and / or rotation motion. Adaptive MVD accuracy is applied to both translation motion and warping motion, and MVD settings (e.g., accuracy limit, magnitude range) are customized for warping motion mode and translation motion mode in inter-prediction of video data. By these means, MVD accuracy, accuracy limit, magnitude, and / or magnitude range can be separately optimized for warping motion mode and translation motion mode.

[0018] 1 is a block diagram illustrating a communication system 100 according to some embodiments. Communication system 100 includes a source device 102 and a plurality of electronic devices 120 (e.g., electronic devices 120-1 through 120-m) communicatively coupled to each other via one or more networks. In some embodiments, communication system 100 is a streaming system for use in video-enabled applications such as, for example, video conferencing applications, digital TV applications, and media storage and / or distribution applications.

[0019] Source device 102 includes a video source 104 (e.g., a camera component or media storage) and an encoder component 106. In some embodiments, video source 104 is a digital camera (e.g., configured to generate an uncompressed video sample stream). Encoder component 106 generates one or more encoded video bitstreams from the video stream. The video stream from video source 104 may have a high data volume compared to encoded video bitstream 108 generated by encoder component 106. Because encoded video bitstream 108 has a lower data volume (less data) compared to the video stream from the video source, encoded video bitstream 108 requires less bandwidth for transmission and less storage space for storage compared to the video stream from video source 104. In some embodiments, source device 102 does not include encoder component 106 (e.g., configured to transmit uncompressed video data to network(s) 110).

[0020] The one or more networks 110 represent any number of networks that convey information between the source device 102, the server system 112, and / or the electronic device 120, including, for example, wired (cabled) and / or wireless communication networks. The one or more networks 110 may exchange data over circuit-switched and / or packet-switched channels. Exemplary networks include telecommunications networks, local area networks, wide area networks, and / or the Internet.

[0021] The one or more networks 110 include a server system 112 (e.g., a distributed / cloud computing system). In some embodiments, the server system 112 is or includes a streaming server (e.g., configured to store and / or distribute video content, such as an encoded video stream from the source device 102). The server system 112 includes a coder component 114 (e.g., configured to encode and / or decode video data). In some embodiments, the coder component 114 includes an encoder component and / or a decoder component. In various embodiments, the coder component 114 is instantiated as hardware, software, or a combination thereof. In some embodiments, the coder component 114 is configured to decode the encoded video bitstream 108 and re-encode the video data using a different encoding standard and / or method to generate encoded video data 116. In some embodiments, the server system 112 is configured to generate multiple video formats and / or encodings from the encoded video bitstream 108.

[0022] In some embodiments, server system 112 functions as a media-enabled network element (MANE). For example, server system 112 may be configured to prune encoded video bitstream 108 to adapt potentially different bitstreams to one or more of electronic devices 120. In some embodiments, a MANE is provided separate from server system 112.

[0023] Electronic device 120-1 includes a decoder component 122 and a display 124. In some embodiments, decoder component 122 is configured to decode encoded video data 116 to generate an output video stream that can be rendered on a display or other type of rendering device. In some embodiments, one or more of electronic devices 120 does not include a display component (e.g., communicatively coupled to an external display device and / or includes media storage). In some embodiments, electronic device 120 is a streaming client. In some embodiments, electronic device 120 is configured to access server system 112 to obtain encoded video data 116.

[0024] The source device and / or the plurality of electronic devices 120 may also be referred to as “terminal devices” or “user devices.” In some embodiments, the source device 102 and / or one or more of the electronic devices 120 are instances of a server system, a personal computer, a portable device (e.g., a smartphone, tablet, or laptop), a wearable device, a videoconferencing device, and / or other types of electronic devices.

[0025] In an exemplary operation of communication system 100, source device 102 transmits encoded video bitstream 108 to server system 112. For example, source device 102 may code a stream of pictures captured by the source device. Server system 112 may receive encoded video bitstream 108 and decode and / or encode encoded video bitstream 108 using coder component 114. For example, server system 112 may apply optimal encoding to the video data for network transmission and / or storage. Server system 112 may transmit encoded video data 116 (e.g., one or more coded video bitstreams) to one or more of electronic devices 120. Each electronic device 120 may decode encoded video data 116 to recover, and optionally display, video pictures.

[0026] In some embodiments, the transmission is a unidirectional data transmission. Unidirectional data transmission may be utilized in media serving applications, etc. In some embodiments, the transmission is a bidirectional data transmission. Bidirectional data transmission may be utilized in video conferencing applications, etc. In some embodiments, the encoded video bitstream 108 and / or the encoded video data 116 are encoded and / or decoded according to any of the video coding / compression standards described herein, such as HEVC, VVC, and / or AV1.

[0027] FIG. 2A is a block diagram illustrating exemplary elements of the encoder component 106 according to some embodiments. The encoder component 106 receives a source video sequence from a video source 104. In some embodiments, the encoder component includes a receiver (e.g., transceiver) component configured to receive the source video sequence. In some embodiments, the encoder component 106 receives a video sequence from a remote video source (e.g., a video source that is a component of a device different from the encoder component 106). The video source 104 may provide the source video sequence in the form of a digital video sample stream that may be of any suitable bit depth (e.g., 8-bit, 10-bit, or 12-bit), any color space (e.g., BT.601 Y CrCb, or RGB), and any suitable sampling structure (e.g., Y CrCb 4:2:0 or Y CrCb 4:4:4). In some embodiments, the video source 104 is a storage device that stores previously captured / prepared video. In some embodiments, the video source 104 is a camera that captures local image information as a video sequence. Video data may be provided as multiple individual pictures that, when viewed sequentially, convey motion. The pictures themselves are organized as a spatial array of pixels, each of which may contain one or more samples, depending on the sampling structure, color space, etc., in use. Those skilled in the art will readily understand the relationship between pixels and samples. The following discussion focuses on samples.

[0028] The encoder component 106 is configured to code and / or compress pictures of a source video sequence into a coded video sequence 216 in real time or under other time constraints required by the application. Enforcing an appropriate coding rate is one function of the controller 204. In some embodiments, the controller 204 controls and is operatively coupled to other functional units described below. Parameters set by the controller 204 may include rate control-related parameters (e.g., picture skip, quantizer, and / or lambda value for rate-distortion optimization techniques), picture size, Group of Pictures (GOP) layout, maximum motion vector search range, etc. Those skilled in the art can readily identify other functions of the controller 204 that may be associated with the encoder component 106 being optimized for a particular system design.

[0029] In some embodiments, the encoder component 106 is configured to operate in a coding loop. In a simplified example, the coding loop includes a source coder 202 (e.g., responsible for generating symbols, such as a symbol stream, based on an input picture to be coded and one or more reference pictures) and a (local) decoder 210. The decoder 210 reconstructs the symbols to generate sample data, similar to a (remote) decoder (when the compression between the symbols and the coded video bitstream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory 208. Because decoding the symbol stream produces bit-exact results regardless of the location of the decoder (local or remote), the contents of the reference picture memory 208 are also bit-exact between the local and remote encoders. In this way, the predictor of the encoder interprets the same sample values as reference picture samples as the decoder interprets when using prediction during decoding. This principle of reference picture synchrony (and the resulting drift if synchrony cannot be maintained, e.g., due to channel error) is known to those skilled in the art.

[0030] The operation of decoder 210 may be the same as that of a remote decoder, such as decoder component 122, described in detail below in connection with Figure 2B. However, with brief reference to Figure 2B, because symbols are available and the encoding / decoding of the symbols into a coded video sequence by entropy coder 214 and parser 254 may be lossless, the entropy decoding portion of decoder component 122, including buffer memory 252 and parser 254, may not be fully implemented in local decoder 210.

[0031] At this point, it can be said that any decoder technology other than parsing / entropy decoding present in a decoder must also necessarily be present in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter focuses on the operation of the decoder. A description of the encoder technology can be omitted, since the encoder technology is the opposite of the decoder technology, which is described generically. Only in certain areas is a more detailed description necessary, as presented below.

[0032] As part of its operation, source coder 202 may perform motion-compensated predictive coding, which predictively codes an input frame with reference to one or more previously coded frames from a video sequence designated as reference frames. In this manner, coding engine 212 codes differences between pixel blocks of the input frame and pixel blocks of reference frame(s) that may be selected as predictive references for the input frame. Controller 204 may manage the coding operations of source coder 202, including, for example, setting parameters and subgroup parameters used to encode the video data.

[0033] The decoder 210 decodes the coded video data of frames that may be designated as reference frames based on symbols created by the source coder 202. The operation of the coding engine 212 may advantageously be a lossy process. When the coded video data is decoded by a video decoder (not shown in FIG. 2A ), the reconstructed video sequence may be a replica of the source video sequence, typically with some errors. The decoder 210 may replicate the decoding process that may be performed by a remote video decoder on the reference frames and store the reconstructed reference frames in the reference picture memory 208. In this way, the encoder component 106 locally stores copies of the reconstructed reference frames that have common content as the reconstructed reference frames that will be obtained by the remote video decoder (without transmission errors).

[0034] The predictor 206 may perform a predictive search for the coding engine 212. That is, for a new frame to be coded, the predictor 206 may search the reference picture memory 208 for sample data (as candidate reference pixel blocks) or specific metadata such as reference picture motion vectors, block shapes, etc. that may serve as suitable predictive references for the new picture. The predictor 206 may operate on sample block by pixel block to find a suitable predictive reference. In some cases, as determined by the search results obtained by the predictor 206, the input picture may have predictive references drawn from multiple reference pictures stored in the reference picture memory 208.

[0035] The outputs of all the aforementioned functional units may undergo entropy coding in entropy coder 214. Entropy coder 214 converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols according to techniques known to those skilled in the art (e.g., Huffman coding, variable length coding, and / or arithmetic coding).

[0036] In some embodiments, the output of the entropy coder 214 is coupled to a transmitter. The transmitter may be configured to buffer the coded video sequence(s) generated by the entropy coder 214 and prepare them for transmission over a communication channel 218, which may be a hardware / software link to a storage device that stores the encoded video data. The transmitter may be configured to merge the coded video data from the source coder 202 with other data to be transmitted, such as coded audio data and / or an auxiliary data stream (source not shown). In some embodiments, the transmitter may transmit additional data along with the encoded video. The source coder 202 may include such data as part of the coded video sequence. The additional data may include other forms of redundant data, such as temporal / spatial / SNR enhancement layers, redundant pictures and slices, supplemental enhancement information (SEI) messages, visual usability information (VUI) parameter set fragments, etc.

[0037] The controller 204 may manage the operation of the encoder component 106. During coding, the controller 204 may assign a specific coded picture type to each coded picture, which may affect the coding technique applied to the respective picture. For example, a picture may be assigned as an intra picture (I picture), a predicted picture (P picture), or a bidirectionally predicted picture (B picture). An intra picture may be coded and decoded without using any other frame in the sequence as a source of prediction. Some video codecs allow various types of intra pictures, including, for example, independent decoder refresh (IDR) pictures. Those skilled in the art will recognize these variations of I pictures and their respective uses and characteristics, so they will not be repeated here. A predicted picture may be coded and decoded using intra prediction or inter prediction, which uses at most one motion vector and reference index to predict sample values for each block. Bidirectionally predicted pictures can be coded and decoded using intra or inter prediction, which uses up to two motion vectors and reference indices to predict the sample values of each block. Similarly, multiple predicted pictures can use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0038] A source picture is generally spatially subdivided into multiple sample blocks (e.g., blocks of 4x4 samples, 8x8 samples, 4x8 samples, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks as determined by the coding assignment applied to the block's respective picture. For example, blocks of an I-picture may be nonpredictively coded or predictively coded with reference to already coded blocks of the same picture (spatial prediction or intra-prediction). Pixel blocks of a P-picture may be nonpredictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. Pixel blocks of a B-picture may be nonpredictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

[0039] Video may be captured in time sequence as multiple source pictures (video pictures). Intra-picture prediction (often abbreviated as intra-prediction) uses spatial correlation within a given picture, while inter-picture prediction uses correlation (temporal or other) between pictures. In one example, a particular picture being encoded / decoded, called the current picture, is divided into blocks. When a block in the current picture is similar to a reference block in a previously coded and still buffered reference picture in the video, the block in the current picture may be coded by a vector called a motion vector. The motion vector points to a reference block in the reference picture and may have a third dimension that identifies the reference picture if multiple reference pictures are used.

[0040] Encoder component 106 may perform coding operations in accordance with a predetermined video coding technique or standard, such as any of those described herein. In doing so, encoder component 106 may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence. Thus, the coded video data may conform to a syntax specified by the video coding technique or standard being used.

[0041] 2B is a block diagram illustrating exemplary elements of the decoder component 122 according to some embodiments. The decoder component 122 of FIG. 2B is coupled to the channel 218 and the display 124. In some embodiments, the decoder component 122 includes a transmitter coupled to the loop filter 256 and configured to transmit data to the display 124 (e.g., via a wired or wireless connection).

[0042] In some embodiments, decoder component 122 includes a receiver coupled to channel 218 and configured to receive data from channel 218 (e.g., via a wired or wireless connection). The receiver may be configured to receive one or more coded video sequences to be decoded by decoder component 122. In some embodiments, the decoding of each coded video sequence is independent of the other coded video sequences. Each coded video sequence may be received from channel 218, which may be a hardware / software link to a storage device that stores the encoded video data. The receiver receives the encoded video data along with other data, e.g., coded audio data and / or auxiliary data streams, which may be forwarded to their respective using entities (not shown). The receiver may separate the coded video sequence from the other data. In some embodiments, the receiver receives additional (redundant) data along with the encoded video. The additional data may be included as part of the coded video sequence(s). The additional data may be used by decoder component 122 to decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, a temporal layer, a spatial layer, or an SNR enhancement layer, redundant slices, redundant pictures, forward error correction codes, etc.

[0043] According to some embodiments, the decoder component 122 includes a buffer memory 252, a parser 254 (sometimes referred to as an entropy decoder), a scaler / inverse transform unit 258, an intra-picture prediction unit 262, a motion compensation prediction unit 260, an aggregator 268, a loop filter unit 256, a reference picture memory 266, and a current picture memory 264. In some embodiments, the decoder component 122 is implemented as an integrated circuit, a series of integrated circuits, and / or other electronic circuitry. In some embodiments, the decoder component 122 is implemented at least partially in software.

[0044] Buffer memory 252 is coupled between channel 218 and parser 254 (e.g., to combat network jitter). In some embodiments, buffer memory 252 is separate from decoder component 122. In some embodiments, a separate buffer memory is provided between the output of channel 218 and decoder component 122. In some embodiments, in addition to buffer memory 252 within decoder component 122 (e.g., configured to handle playout timing), a separate buffer memory is provided external to decoder component 122 (e.g., to combat network jitter). When receiving data from a storage / forwarding device with sufficient bandwidth and controllability or from an isosynchronous network, buffer memory 252 may be unnecessary or can be small. For use in best-effort packet networks such as the Internet, buffer memory 252 may be required, and may be relatively large, advantageously adaptively sized, and at least partially implemented in an operating system or similar element (not shown) external to decoder component 122.

[0045] The parser 254 is configured to reconstruct symbols 270 from the coded video sequence. The symbols may include, for example, information used to manage the operation of the decoder component 122 and / or information for controlling a rendering device such as the display 124. The control information for the rendering device(s) may be in the form of a Supplemental Enhancement Information (SEI) message or a Video Usability Information (VUI) parameter set fragment (not shown). The parser 254 parses (entropy decodes) the coded video sequence. The coding of the coded video sequence may follow a video coding technique or standard and may follow principles well known to those skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, etc. The parser 254 may extract a set of subgroup parameters for at least one 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), etc. Parser 254 may extract information from the coded video sequence, such as transform coefficients, quantization parameter values, motion vectors, and the like.

[0046] The reconstruction of symbols 270 may involve several different units, depending on the type of video picture or portion thereof being coded (inter-picture and intra-picture, inter-block and intra-block, etc.), as well as other factors. Which units are involved and how they are involved may be controlled by subgroup control information parsed from the coded video sequence by parser 254. The flow of such subgroup control information between parser 254 and the following units is not depicted for convenience of explanation.

[0047] In addition to the functional blocks already mentioned, the decoder component 122 can be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these units will interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, the conceptual subdivision into the following functional units will be maintained:

[0048] The scaler / inverse transform unit 258 receives the quantized transform coefficients as well as control information (e.g., which transform to use, block size, quantization coefficients, and / or quantization scaling matrix) as symbol(s) 270 from the parser 254. The scaler / inverse transform unit 258 may output blocks containing sample values that may be input to an aggregator 268.

[0049] In some cases, the output samples of the scaler / inverse transform unit 258 relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture but can use prediction information from a previously reconstructed portion of the current picture. Such prediction information may be provided by the intra-picture prediction unit 262. The intra-picture prediction unit 262 may generate blocks of the same size and shape as the block being reconstructed using surrounding already reconstructed information fetched from the current (partially reconstructed) picture from the current picture memory 264. The aggregator 268 may add, on a sample-by-sample basis, the prediction information generated by the intra-picture prediction unit 262 to the output sample information provided by the scaler / inverse transform unit 258.

[0050] In other cases, the output samples of the scalar / inverse transform unit 258 relate to an inter-coded, potentially motion-compensated, block. In such cases, the motion-compensated prediction unit 260 may access the reference picture memory 266 to fetch samples used for prediction. After motion-compensating the fetched samples according to the symbols 270 associated with the block, these samples may be added to the output of the scalar / inverse transform unit 258 by the aggregator 268 to generate output sample information (in this case, referred to as residual samples or a residual signal). The addresses in the reference picture memory 266 from which the motion-compensated prediction unit 260 fetches the prediction samples may be controlled by a motion vector. The motion vector may be available to the motion-compensated prediction unit 260 in the form of a symbol 270, which may have, for example, X, Y, and reference picture components. Motion compensation may also include interpolation of fetched sample values from the reference picture memory 266 when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, and the like.

[0051] The output samples of aggregator 268 may be subjected to various loop filtering techniques in loop filter unit 256. Video compression techniques may include in-loop filter techniques controlled by parameters included in the coded video bitstream and made available to loop filter unit 256 as symbols 270 from parser 254, but may also be responsive to meta-information obtained during decoding of a coded picture or previous portion (in decoding order) of the coded video sequence, or to previously reconstructed and loop-filtered sample values.

[0052] The output of the loop filter unit 256 may be a sample stream that can be output to a rendering device such as the display 124, as well as stored in the reference picture memory 266 for use in future inter-picture prediction.

[0053] Once fully reconstructed, a particular coded picture can be used as a reference picture for future prediction. Once a coded picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by parser 254), the current reference picture can become part of reference picture memory 266, and a new current picture memory can be reallocated before starting reconstruction of the next coded picture.

[0054] Decoder component 122 may perform decoding operations according to a predetermined video compression technology, which may be documented in a standard, such as any of the standards described herein. The coded video sequence may conform to the syntax specified by the video compression technology or standard being used, in the sense of adhering to the syntax of the video compression technology or standard as specified in the video compression technology document or standard, specifically the profile document therein. Also, to comply with some video compression technologies or standards, the complexity of the coded video sequence may also be within a range specified by the level of the video compression technology or standard. In some cases, the level limits the maximum picture size, maximum frame rate, maximum reconstruction sample rate (e.g., measured in megasamples per second), maximum reference picture size, etc. The limits set by the level may, in some cases, be further limited by a hypothetical reference decoder (HRD) specification and metadata for HRD buffer management signaled in the coded video sequence.

[0055] 3 is a block diagram illustrating a server system 112 according to some embodiments. The server system 112 includes a control circuit 302, one or more network interfaces 304, a memory 314, a user interface 306, and one or more communication buses 312 for interconnecting these components. In some embodiments, the control circuit 302 includes one or more processors (e.g., a CPU, a GPU, and / or a DPU). In some embodiments, the control circuit includes one or more field programmable gate arrays (FPGAs), hardware accelerators, and / or one or more integrated circuits (e.g., application specific integrated circuits).

[0056] The network interface(s) 304 may be configured to interface with one or more communications networks (e.g., wireless, wired, and / or optical networks). Communications networks may be local, wide-area, metropolitan, vehicular and industrial, real-time, delay-tolerant, etc. Examples of communications networks include local area networks such as Ethernet; cellular networks including WLAN, GSM, 3G, 4G, 5G, LTE, etc.; television wired or wireless wide-area digital networks including cable, satellite, and terrestrial television; vehicular and industrial networks including CANBus; and the like. Such communications may be unidirectional, receive only (e.g., broadcast television), unidirectional transmit only (e.g., CANbus to a specific CANbus device), or bidirectional (e.g., to another computer system using a local or wide-area digital network). Such communications may include communications to one or more cloud computing networks.

[0057] The user interface 306 includes one or more output devices 308 and / or one or more input devices 310. The input device(s) 310 may include one or more of a keyboard, a mouse, a trackpad, a touchscreen, a data glove, a joystick, a microphone, a scanner, a camera, etc. The output device(s) 308 may include one or more of an audio output device (e.g., a speaker), a visual output device (e.g., a display or monitor), etc.

[0058] Memory 314 may include high-speed random-access memory (such as DRAM, SRAM, DDR RAM, and / or other random-access solid-state memory devices) and / or non-volatile memory (such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, and / or other non-volatile solid-state storage devices). Memory 314 optionally includes one or more storage devices located remotely from control circuitry 302. Memory 314, or the non-volatile solid-state memory device(s) within memory 314, comprises a non-transitory computer-readable storage medium. In some embodiments, memory 314, or the non-transitory computer-readable storage medium of memory 314, stores the following programs, modules, instructions, and data structures, or a subset or superset thereof: • an operating system 316 that contains procedures for handling various basic system services and performing hardware-dependent tasks; • a network communications module 318 used to connect the server system 112 to other computing devices via one or more network interfaces 304 (e.g., via wired and / or wireless connections); A coding module 320 for performing various functions related to encoding and / or decoding data, such as video data. In some embodiments, the coding module 320 is an instance of the coder component 114. The coding module 320 may include, but is not limited to, one or more of the following: a decoding module 322 for performing various functions related to decoding the encoded data, such as those described above with respect to the decoder component 122; an encoding module 340 for performing various functions on the encoded data, such as those described above with respect to the encoder component 106; A picture memory 352 for storing pictures and picture data, e.g., for use with the coding module 320. In some embodiments, the picture memory 352 includes one or more of the reference picture memory 208, the buffer memory 252, the current picture memory 264, and the reference picture memory 266.

[0059] In some embodiments, the decoding module 322 includes a parsing module 324 (e.g., configured to perform the various functions described above with respect to the parser 254), a transform module 326 (e.g., configured to perform the various functions described above with respect to the scalar / inverse transform unit 258), a prediction module 328 (e.g., configured to perform the various functions described above with respect to the motion compensation prediction unit 260 and / or the intra-picture prediction unit 262), and a filter module 330 (e.g., configured to perform the various functions described above with respect to the loop filter 256).

[0060] In some embodiments, the encoding module 340 includes a code module 342 (e.g., configured to perform various functions described above with respect to the source coder 202 and / or the coding engine 212) and a prediction module 344 (e.g., configured to perform various functions described above with respect to the predictor 206). In some embodiments, the decoding module 322 and / or the encoding module 340 include a subset of the modules shown in Figure 3. For example, a shared prediction module is used by both the decoding module 322 and the encoding module 340.

[0061] Each of the above-identified modules stored in memory 314 corresponds to a set of instructions for performing functions described herein. The above-identified modules (e.g., instruction sets) need not be implemented as separate software programs, procedures, or modules; thus, various subsets of these modules may be combined or otherwise rearranged in various embodiments. For example, coding module 320 optionally does not include separate decoding and encoding modules, but rather uses the same set of modules to perform both sets of functions. In some embodiments, memory 314 stores a subset of the above-identified modules and data structures. In some embodiments, memory 314 stores additional modules and data structures not described above, such as an audio processing module.

[0062] In some embodiments, the server system 112 includes a web or Hypertext Transfer Protocol (HTTP) server, a File Transfer Protocol (FTP) server, and web pages and applications implemented using Common Gateway Interface (CGI) scripts, the PHP Hypertext Preprocessor (PHP), Active Server Pages (ASP), Hypertext Markup Language (HTML), Extensible Markup Language (XML), Java, JavaScript, Asynchronous JavaScript and XML (AJAX), XHP, Javelin, Wireless Universal Resource Files (WURFL), and the like.

[0063] While Figure 3 illustrates a server system 112 according to some embodiments, Figure 3 is not intended as an architectural schematic of the embodiments described herein, but rather as a functional description of various features that may be present in one or more server systems. In practice, and as will be recognized by those skilled in the art, items shown separately may be combined and some items may be separated. For example, some items shown separately in Figure 3 may be implemented on a single server, and a single item may be implemented by one or more servers. The actual number of servers used to implement server system 112 and how functionality is allocated among them will vary from implementation to implementation and, optionally, depend in part, on the amount of data traffic the server system handles during peak and average usage periods.

[0064] FIG. 4A is a schematic diagram of an inter-predictive coding configuration 400 that associates a current coding block 404 with a reference block 408, according to some embodiments, and FIG. 4B is a schematic diagram of an inter-predictive coding configuration 450 in which a motion vector differential (MVD) is identified within an MVD adaptation region 414 of a reference frame 406, according to some embodiments. A Group of Pictures (GOP) comprises a sequence of image frames. The image frames include a current image frame 402 that further includes a current coding block 404. The current coding block 404 is encoded based on one or more reference blocks 408 of one or more reference frames 406 within the GOP. For example, referring to FIG. 4A , the current coding block 404 is encoded based on the reference block 408 within the reference frame 406, which optionally precedes or follows the current frame 402. In some embodiments, the reference frame 406 immediately precedes the current frame 402 within the GOP. Alternatively, in some embodiments, the reference frame 406 immediately follows the current frame 402 in the GOP. Alternatively, in some embodiments, the reference frame 406 is separated from the current frame 402 by a number of frames in the GOP (e.g., three frames).

[0065] In some embodiments, the current coding block 404 is determined based on a reference block 404 in a translational motion mode, in which the sub-blocks or samples of the current coding block 404 have no internal relative displacement with respect to one another. A motion vector 410 of the current coding block 404 is applied to code and predict each sub-block or sample of the current coding block 404 based on a respective reference sub-block or sample of the reference block 408. Conversely, in some embodiments, the current coding block 404 is determined based on a reference block 404 in a warping motion mode, in which the sub-blocks or samples of the current coding block 404 have internal relative displacement with respect to one another. The motion vector 410 of the current coding block 404 is adjusted for each sub-block or sample of the current coding block 404 before the motion vector 410 is used to code or predict the sub-block or sample based on a respective reference sub-block or sample of the reference block 408.

[0066] In some embodiments, the motion vector 410 of the current coding block 404 is a combination of motion vector prediction (MVP) and MVD. The MVP is fixed, and the MVD is adaptively encoded for the current coding block 404. Referring to FIG. 4B , in some embodiments, the MVP identifies a center of a predicted reference block 412-P for the current coding block 404. Multiple candidate reference blocks 412 (e.g., 412-P, 412-1 to 412-7, centered on D1 to D7) are identified within an MVD adaptation region 414 that includes the predicted reference block 412-P. The MVD adaptation region 414 is defined based on an MVD magnitude range, which is one of multiple MVD adjustment parameters for the current coding block 404. An exemplary MVD magnitude range corresponds to 32 pixels. In one example, the center of each of the multiple candidate reference blocks 412 (e.g., 412-1 to 412-7, centered on D1 to D7) is within a distance of 32 pixels of the center P of the reference block 412-P. Alternatively, in another example, both the x-axis displacement and the y-axis displacement of each candidate reference block 412 are within 32 pixels of the center P of the reference block 412-P. In some embodiments, the centers of the multiple candidate reference blocks (412-R and 412-1 through 412-7) are separated by at least an MVD precision limit, which is the other of the multiple MVD adjustment parameters of the current coding block 404. An exemplary MVD precision limit corresponds to a quarter of a pixel (e.g., ¼-pel resolution). For example, the centers of any two of the multiple candidate reference blocks 412 (e.g., 412-1 through 412-7) are separated by at least ¼ pixel. Alternatively, the x-axis displacement and the y-axis displacement of any two centers of the candidate reference blocks 412 are ¼ pixel or greater. In some embodiments, the MVD precision limit is the finest supported MVD precision. Alternatively, in some embodiments, the MVD precision limit is the coarsest supported MVD precision. In other words, in some embodiments, the minimum distance of the centers of the candidate reference blocks 412 has different settings (eg, values) in warping and translation motion modes, as does the size of the MVD adaptation region 414.

[0067] In some embodiments, adaptive MVD is applied regardless of the translation motion mode and the warping motion mode, and the same MVD settings are applied to the MVD adaptation parameters in these two motion modes. Conversely, adaptive MVD is applied in the translation motion mode and the warping motion mode, and different MVD settings of the MVD adaptation parameters (e.g., multiple MVD accuracies within the MVD accuracy range, MVD accuracy limits, MVD size ranges) are used in these two motion modes. The accuracy range is limited by MVD accuracy limits, such as the finest and coarsest accuracy. For example, a first MVD accuracy limit is applied in the warping motion mode, and a second MVD accuracy limit is applied in the translation motion mode. The second MVD accuracy limit is different from the first MVD accuracy limit, i.e., has a different value. In some situations, the first MVD accuracy limit in the warping motion mode is equal to half a pixel, which is higher than the second MVD accuracy limit in the translation motion mode (e.g., 1 / 4 or 1 / 8 of a pixel). Conversely, in some circumstances, the first MVD precision limit of the warping motion mode is equal to 1 / 8 of a pixel, which is lower than the second MVD precision limit of the translation motion mode (eg, half a pixel).

[0068] In another example, a first MVD magnitude range is applied in the warping motion mode, and a second MVD magnitude range is applied in the translation motion mode. The second MVD magnitude range is different from the first MVD magnitude range. In some circumstances, the first MVD magnitude range in the warping motion mode is equal to 32 pixels, which is greater than the second MVD magnitude range (e.g., 8 pixels) in the translation motion mode. Conversely, in some circumstances, the first MVD magnitude range in the warping motion mode is equal to 8 pixels, which is less than the second MVD magnitude range (e.g., 32 pixels) in the translation motion mode.

[0069] In some embodiments, according to the adaptive MVD determination, one of the multiple candidate reference blocks (e.g., 412-2) is identified as the reference block 408 of the current coding block 404, and an MVD is associated with the identified reference block 408 of the current block 404. The motion vector prediction MVP and MVD of the current coding block 404 are coded in a bitstream by the encoder 106 and transmitted to the decoder 122. In some embodiments, the warping motion mode and the translation motion mode are associated with different encoding contexts. According to a determination that the current coding block is coded in the warping motion mode, a first context for entropy encoding the current coding block is determined. According to a determination that the current coding block is coded in the translation motion mode, a second context for entropy encoding the current coding block is determined. The second context is different from the first context. Upon receiving the bitstream, the encoder 122 extracts the MVD of the current coding block 404 based on whether the warping motion mode or the translation motion mode is applied. Specifically, one or more MVD settings of the current coding block 404 are determined based on the motion mode, and the MVDs of the current coding block 404 and the reference blocks are determined based on the one or more MVD settings.

[0070] In some embodiments, the current coding block 404 is coded in a warping motion mode, and a first MVD setting is selected to reconstruct the current coding block 404. The alternative coding block 424 of the current image frame 402 is different from the current coding block 404. The alternative coding block 424 of the current image frame 402 is determined to have been coded in a translation mode. A second MVD setting is selected for the alternative coding block 424 such that the alternative coding block 424 is reconstructed based at least in part on the second MVD setting. Thus, different coding blocks of the current coding block 402 may have different motion modes and different MVD settings.

[0071] 5 is a schematic diagram of a bilateral matching configuration 500 for associating a current coding block 404 in a GOP with two reference blocks 408A and 408B located within the same GOP based on two different motion vectors 410A and 410B, according to some embodiments. In some embodiments, bilateral matching or template matching is applied to encode the current coding block 404. For example, the current coding block 400 is encoded based on prediction data of two reference blocks 408A and 408B of two reference images 406A and 406B within the GOP. In one example, the current coding block 404 is temporally located between a first reference block 408A and a second reference block 408B. One of the reference blocks 408A and 408B precedes the current coding block 400, and the other of the reference blocks 408A and 408B follows the current coding block 400. Each reference frame 406A or 406B is either directly adjacent to the current frame 402 or separated from the current frame 402 by several frames.

[0072] In some embodiments, the current coding block 404 is coded based on two reference blocks 408A and 408B in a translation motion mode. In some embodiments, the current coding block 404 is coded based on two reference blocks 408A and 408B in a warping motion mode. The motion vector 410A or 410B of the current coding block 404 is adjusted based on the warping motion for each sub-block or sample of the current coding block 404 before the motion vector 410A or 410B is used to code or predict a sub-block or sample based on the respective reference sub-block or sample of the reference block 408A or 408B. Additionally, in some embodiments related to bilateral matching, the MVD of the motion vector 410A or 410B is adaptively determined independent of the translation motion mode and the warping motion mode, and the same MVD setting is applied to these two motion modes. Conversely, in some embodiments related to bilateral matching, the MVD of the motion vector 410A or 410B is adaptively determined in both the translation motion mode and the warping motion mode, and different MVD settings (e.g., multiple accuracies within the MVD accuracy range, MVD accuracy limits, MVD magnitude range) are used in these two motion modes.

[0073] FIG. 6A illustrates a block diagram of a reference block (e.g., 608A, 608B) for which the MVD (e.g., MVD A , MVD B6B is a schematic diagram of a bilateral matching configuration 600 in which the MVD of a reference block 608A is refined within an MVD refinement range 620, according to some embodiments. The MVD of a motion vector 410A or 410B is adaptively determined within the MVD adaptation region 414 ( FIG. 4B ) in either the warping motion mode or the translation motion mode. In some embodiments, the adaptive MVDs for the warping motion mode and the translation motion mode are obtained based on the same MVD setting (e.g., corresponding to the same candidate reference block 412 within the MVD adaptation region 414). Alternatively, in some embodiments, one or more MVD settings are different in the warping motion mode and the translation motion mode (e.g., corresponding to different candidate reference blocks 412 within the MVD adaptation region 414 having different sizes). The corresponding MVD setting is determined based on the first MVD (MVD A ) in warping or translation motion modes.

[0074] Additionally, a first MVD (MVD A ) is the first refined MVD (RMVD) corresponding to the refined first motion vector 610A of the refined first reference block 608A. A The first motion vector 610A is further refined based on a cost criterion of the difference between the first and second reference blocks 408A and 408B to generate a first MVD (MVD A ) is transmitted from the encoder 106 to the decoder 122. Conversely, the first refined MVD (RMVD A ) is not transmitted along with the MVD, but is determined separately at both the encoder 106 and the decoder 122. The first motion vector 610A is obtained by the first motion vector prediction MVP- A , the first MVD (MVD A ), and the first refined MVD (RMVD A) of the second reference block 408B. B ) is refined by a second refined MVD (RMVD B ) is determined. The second refined MVD (RMVD B ) corresponds to the refined second motion vector 610B of the refined second reference block 608B. In some embodiments, the first refined MVD (RMVD A ) are mirrored to generate an intermediate MVD, which is a second refined MVD (RMVD) based on the ratio of two distances from the current coding block 404 to the first and second reference blocks 608A and 608B, i.e., the ratio of the first distance between the two blocks 404 and 608A to the second distance between the two blocks 404 and 608B. B )

[0075] In some embodiments, only the first motion vector 610A of the first reference block 608A is used to calculate the first refined MVD (RMVD) at the block level. A) in the warping motion mode. In the warping motion mode, the first motion vector 610A is adjusted for each sub-block or sample of the current coding block 404 before the motion vector 610A is used to code or predict the sub-block or sample based on a respective reference sub-block or sample of the reference block 608A. Specifically, in some embodiments, the first motion vector 610A of the current coding block 404 is applied to determine a sub-block motion vector (e.g., vector 604A) for each set of sub-blocks (e.g., first sub-block 602) of the current coding block 404 in accordance with a determination that the current coding block 404 is coded in the warping motion mode. Furthermore, in some embodiments, the current coding block 404 includes the first sub-block 602. The first sub-block has two reference blocks, including a first reference sub-block 606A in the first reference frame 406A and a second reference sub-block in the second reference frame 406B. Based on a cost metric of the difference between the first and second reference sub-blocks, the sub-block MVD associated with the first reference sub-block 606A is refined to determine a refined sub-block MVD, e.g., at the sub-block level. A sub-block motion vector 604A is refined for the first sub-block 602 based on the sub-block refined MVD associated with the first reference sub-block 606A.

[0076] The first motion vector 610A is the first motion vector prediction MVP- A , the first MVD (MVD A ), and the first refined MVD (RMVD A Note that the first MVD of the first motion vector 610A (MVD A ) is determined based on one or more MVD settings (e.g., MVD precision limit, MVD magnitude range), and the motion vector prediction MVP AFurther details regarding adaptive MVD determination are described above with reference to FIG. 4B. In addition, the first refined MVD (RMVD A ) is determined based on a cost criterion of the difference between the first and second reference blocks 608A and 608B. The difference between the first and second reference blocks 608A and 608B includes one of the sum of absolute differences (SAD), sum of squared errors (SAE), sum of absolute translated differences (SATD), and sum of mean removed SAD.

[0077] In some embodiments, MVD refinement is performed at both the encoder 106 and the decoder 122. The first refined MVD (RMVD A ) is the first MVD (MVD A ) and are determined separately during MVD refinement in both the encoder 106 and the decoder 122. Referring to FIG. 6B, during MVD refinement, a plurality of refinement options 612 centered on R1 to R6 are identified within an MVD refinement range 620 for a first reference block 608A. It is determined that a difference between the first and second reference blocks 608A and 608B corresponding to one of the plurality of refinement options (e.g., refinement option 612-3 centered on R3) satisfies a cost criterion. For example, according to the cost criterion, refinement option 612-3 provides the smallest difference between the first and second reference blocks 608A and 608B among the plurality of refinement options 612-1 to 612-6. One of the plurality of refinement options that satisfies the cost criterion is selected as the first refined MVD (RMVD). A ) are identified. Further, in some embodiments, during MVD refinement, multiple differences of the first and second reference blocks 608A and 608B are determined for multiple refinement options 612, each difference corresponding to a respective one of the multiple refinement options 612 for the first reference block 610A. The multiple differences are compared to determine whether each difference meets a cost criterion.

[0078] In some embodiments, a subset of the plurality of refinement options (e.g., 612-1 and 612-2) is preferred. The subset of differences is determined based on the subset of preferred refinement options. Before comparing the plurality of differences, the encoder 106 or decoder 122 modifies the subset of differences by a difference factor less than 1, for example, by scaling the subset of differences by the difference factor. Conversely, in some embodiments, a subset of the plurality of refinement options (e.g., 612-3 and 612-4) is less preferred than the remaining refinement options. Before comparing the plurality of differences, the encoder 106 or decoder 122 modifies the subset of differences by a difference factor greater than 1, for example, by scaling the subset of differences by the difference factor.

[0079] 7 is a flow diagram illustrating a method 700 for coding video (e.g., decoding video data) according to some embodiments. Method 700 may be performed in a computing system (e.g., server system 112, source device 102, or electronic device 120) having control circuitry and memory storing instructions for execution by the control circuitry. In some embodiments, method 700 is performed by executing instructions stored in memory of the computing system (e.g., coding module 320 of memory 314). In some embodiments, a flag is applied to indicate whether the current coding block is coded in warped motion mode.

[0080] The video bitstream includes a current coding block 404 in a current image frame 402 (702). The decoder 122 obtains a syntax element value associated with the current coding block 404 in the current image frame 402 (704). The syntax element value is signaled before a motion vector differential (MVD) associated with the current coding block (706). The syntax element value is signaled to indicate whether the current coding block 404 is coded in warping motion mode (708) before the MVD, and the signaling of the current coding block 404 depends on whether the current coding block 404 is coded in warping motion mode (e.g., warping motion mode or translation motion mode). For example, the encoder 106 (FIG. 2A) determines whether the current coding block 404 is coded in warping motion mode or translation motion mode and generates a flag. The decoder 122 receives the flag and determines whether the current coding block 404 is coded in warping motion mode or translation motion mode based on the flag (710). An adaptive MVD is applied to the current coding block 404, and two different sets of MVD settings are applied for coding the warping motion associated with the warping motion mode and the translation motion associated with the translation motion mode. In accordance with a determination that the current coding block 404 is coded in the warping motion mode (712), a first MVD setting is selected for encoding and decoding the current coding block 404. Alternatively, in accordance with a determination that the current coding block 404 is coded in the translation motion mode (714), a second MVD setting is selected for encoding and decoding the current coding block 404. The second MVD setting is different from the first MVD setting.In other words, the first and second MVD settings provide different values for the same set of MVD adjustment parameters (e.g., including a single parameter or multiple parameters) that are applied to determine the MVD for the warping mode or the translation mode. The decoder 122 reconstructs the current coding block 404 based at least in part on the selected MVD setting for the current coding block 404 (716).

[0081] In some embodiments, the two sets of MVD settings have different MVD precision limits. Furthermore, in some embodiments, adaptive MVD precision is applied, where a first MVD precision limit for the warping motion mode (e.g., the first finest supported MVD precision) is different from a second MVD precision limit for the translation motion mode (e.g., the second finest supported MVD precision) (718). In some circumstances, the first MVD precision limit for the warping motion mode is coarser than the second MVD precision limit for the translation motion mode. For example, the finest MVD precision for the warping motion is half of a pixel (also called a picture element (pel)), corresponding to half-pel motion vector precision. The finest MVD precision for the translation motion is one-quarter or one-eighth of a pixel, corresponding to one-quarter or one-eighth pel motion vector precision. Conversely, in some circumstances, the first MVD precision limit for the warping motion mode is finer than the second MVD precision limit for the translation motion mode. For example, the finest MVD precision for warping motion is one-quarter or one-eighth of a pixel, and the finest MVD precision for translation motion is one-half of a pixel.

[0082] Alternatively, in some embodiments, the two sets of MVD precision for the warping motion mode and the translation motion mode have different MVD magnitude ranges. In some embodiments, adaptive MVD precision is applied, and a first MVD magnitude range for the warping motion mode (e.g., a first maximum supported MVD scale) is different from a second MVD magnitude range for the translation motion mode (e.g., a second maximum supported MVD scale) (720). In some circumstances, the first MVD magnitude range for the warping motion mode is smaller than the second MVD magnitude range for the translation motion mode. For example, the first maximum supported MVD scale for the warping motion is 8 pixels, and the second maximum supported MVD scale for the translation motion is 32 pels or greater. Conversely, in some circumstances, the first MVD magnitude range for the warping motion mode is larger than the second MVD magnitude range for the translation motion mode. For example, the first maximum supported MVD scale for the warping motion is 32 pixels, and the second maximum supported MVD scale for the translation motion is 8 pixels.

[0083] In some embodiments, the MVD of the warping motion associated with the warping motion mode is refined using bilateral matching or template matching. This MVD refinement is performed in both the encoder 106 and the decoder 122, and the corresponding MVD refinement result resulting from the MVD refinement is not signaled in the bitstream communicated between the encoder 106 and the decoder 122. Furthermore, in some embodiments, the warping motion and the translation motion are coded with the same set of MVD settings (e.g., MVD precision and magnitude). In some embodiments, the warping motion and the translation motion are coded with different MVD settings.

[0084] In some embodiments, the current coding block 404 is coded in a warped motion mode, and adaptive MVD resolution is applied. For each MVD within the MVD magnitude range (e.g., an allowed / given search area surrounding the motion vector) that includes the motion vector of the current coding block 404, at least one of the prediction blocks P0 or P1 is generated with a respective motion vector 410 that is equal to the sum of the MVD (e.g., a combination of the MVP and the signaled MVD) and the refined MVD. The difference between the prediction blocks P0 and P1 (i.e., 608A and 608B in FIG. 6A) is determined and applied as a cost to further determine whether the cost criteria is met. In one example, the refined MVD (e.g., the RMVD in FIGS. 6A and 6B) that corresponds to the smallest cost value is used. A ) meets the cost criteria and is used to determine the motion vector for the current coding block 404. In some embodiments, the first refined MVD (RMVD A ) is determined for the first prediction block 608A of the first reference frame 406A, and the second refined MVD (RMVD B In one example, the second refined MVD (RMVD B ) is a first refined MVD (RMVD) based on the distance between the first and second reference frames 406 and the current frame 402. A In some embodiments, the distance between the reference frame 406A or 406B and the current frame 402 is determined based on one of SAD (sum of absolute differences), SSE (sum of squared errors), and SATD (sum of absolute translation differences).

[0085] In some embodiments, the distortion cost of one or more specific positions on the reference frames 406A and 406B (FIG. 6B) (e.g., the difference between prediction blocks P0 and P1) is modified by a coefficient to adjust the priority level for using the prediction block associated with each of the positions (e.g., block 612-1 in FIG. 6B) as a reference. When the coefficient is greater than 1, the prediction block associated with the corresponding position is less preferred. When the coefficient is less than 1, the prediction block associated with the corresponding position is more preferred. For example, the distortion cost of a starting position is scaled by a coefficient less than 1, making the prediction block associated with this starting position more preferred than other prediction blocks when these prediction blocks are used as references for the current coding block 404. In this way, adjusting the coefficient reduces computational complexity in the process of refining MVD with bilateral matching.

[0086] In some embodiments, the block-level motion vectors of the current coding block 404 are refined based on the difference between the prediction blocks P0 and P1 and a cost criterion. The sub-blocks 602 of the current coding block 404 are coded in warping motion mode using one or more MVD settings (e.g., MVD precision limit, MVD magnitude range). In one example, the refined MVD (e.g., RMVD A ) is determined using a refinement process, and then the warping motion is adjusted or projected accordingly.

[0087] In addition, in some embodiments, two different sets of motion vector predictions are applied for the warping motion associated with the warping motion mode and the translation motion associated with the translation motion mode, respectively. In some embodiments, the finest MV precision of the warping motion is different (e.g., coarser) than that of the translation motion. For example, the finest MV precision of the warping motion is 1 / 16 pel, and the finest MV precision of the translation motion is 1 / 4 pel or 1 / 8 pel. Alternatively, in some embodiments, the coarsest supported MV precision of the warping motion is different (e.g., smaller) than that of the translation motion. For example, the coarsest supported MV precision of the warping motion is 1 pel, but the finest MV precision of the translation motion is 4 pel or greater.

[0088] In some embodiments, the flag indicates whether the current coding block 404 is coded in warped motion mode and is used to derive a context for entropy coding the MVD of the current coding block 404.

[0089] 7 shows some logical stages in a particular order, but stages that are not order-dependent may be rearranged, and other stages may be combined or separated. Some rearrangements or other groupings not specifically mentioned will be apparent to those skilled in the art, and therefore the rearrangements and groupings presented herein are not exhaustive. Furthermore, it should be recognized that the stages may be implemented in hardware, firmware, software, or any combination thereof.

[0090] Reference will now be made to some exemplary embodiments.

[0091] (A1) In one aspect, some embodiments include a method for processing video data. The method 700 includes receiving (702) a video bitstream including a current coding block (e.g., block 404 in FIGS. 4A-6B ) in a current image frame 402 and obtaining (704) a syntax element value associated with the current coding block in the current image frame. The syntax element value is signaled before a motion vector differential (MVD) associated with the current coding block (706). The syntax element value indicates whether the current coding block is coded in a warped motion mode (708). The method 700 further includes determining (710) whether the current coding block is coded in a warped motion mode or a translation motion mode based on the syntax element value. The method further includes selecting (712) a first motion vector differential (MVD) setting for the current coding block according to a determination that the current coding block is coded in a warped motion mode. The method 700 further includes selecting (714) a second MVD setting for the current coding block according to a determination that the current coding block is coded in translational motion mode, the second MVD setting being different from the first MVD setting. The method 700 further includes reconstructing (716) the current coding block based at least in part on the selected MVD setting for the current coding block.

[0092] (A2) In some embodiments of A1, the first MVD setting includes a first MVD accuracy limit (718) and the second MVD setting includes a second MVD accuracy limit, the first MVD accuracy limit being lower than the second MVD accuracy limit.

[0093] (A3) Alternatively, in some embodiments of A1, the first MVD setting includes a first MVD accuracy limit and the second MVD setting includes a second MVD accuracy limit, the first MVD accuracy limit being higher than the second MVD accuracy limit.

[0094] (A4) In some embodiments of A1-A3, the first MVD setting further includes a first MVD magnitude range (720), and the second MVD setting includes a second MVD magnitude range that is different from the first MVD magnitude range.

[0095] (A5) In some embodiments of A4, the first MVD size range is greater than the second MVD size range.

[0096] (A6) In some embodiments of A4, the first MVD size range is smaller than the second MVD size range.

[0097] (A7) In some embodiments of A1-A6, the method further includes determining (722) that the current coding block has two reference blocks, including a first reference block and a second reference block, and determining a first MVD for the first reference block based on one of a first MVD setting and a second MVD setting. The method further includes refining (724) the first MVD for at least the first reference block to determine a first refined MVD based on a cost criterion of the difference between the first and second reference blocks. The method further includes determining (726) a first motion vector for the current coding block based on the first refined MVD associated with at least the first reference block.

[0098] (A8) In some embodiments of A7, the method further includes determining a second refined MVD for refining the MVD of the second reference block by mirroring the first refined MVD to generate an intermediate MVD and scaling the intermediate MVD to generate the second refined MVD based on a ratio between two distances of the first and second reference blocks from the current coding block.

[0099] (A9) In some embodiments of A7 or A8, the difference between the first and second reference blocks includes one of a sum of absolute differences (SAD), a sum of squared errors (SAE), a sum of absolute transformed differences (SATD), and a sum of mean removed SAD.

[0100] (A10) In some embodiments of A7 to A9, the step of refining the MVD for at least the first reference block further includes the steps of identifying a plurality of refinement options for the first reference block, determining that a difference between the first and second reference blocks corresponding to one of the plurality of refinement options satisfies a cost criterion, and identifying one of the plurality of refinement options as the first refined MVD.

[0101] (A11) In some embodiments of A10, refining the MVD for at least the first reference block further comprises determining a plurality of differences between the first and second reference blocks, and comparing the plurality of differences to determine whether each difference satisfies a cost criterion, each difference corresponding to a respective one of a plurality of refinement options for the first reference block.

[0102] (A12) In some embodiments of A11, determining the plurality of differences further comprises determining a subset of differences based on a subset of refinement options, and modifying the subset of differences by a difference factor less than 1 before comparing the plurality of differences.

[0103] (A13) In some embodiments of A11, determining the plurality of differences further comprises determining a subset of differences based on a subset of refinement options, and modifying the subset of differences by a difference factor greater than 1 before comparing the plurality of differences.

[0104] (A14) In some embodiments of A7 to A13, the method further includes, according to a determination that the current coding block is coded in a warped motion mode, applying a first motion vector of the current coding block to determine a sub-block motion vector for each set of sub-blocks of the current coding block.

[0105] (A15) In some embodiments of A14, the current coding block includes a first sub-block. The method further includes determining that the first sub-block has two reference blocks including a first reference sub-block and a second reference sub-block, refining a sub-block MVD of the first reference sub-block to determine a refined sub-block MVD based on a difference cost metric of the first and second reference sub-blocks, and updating a sub-block motion vector for the first sub-block based on the refined sub-block MVD associated with the first reference sub-block.

[0106] (A16) In some embodiments of A1-A15, the first and second MVD settings each correspond to the finest supported MVD precision for the current coding block.

[0107] (A17) In some embodiments of A1-A15, the first and second MVD settings each correspond to the coarsest port MVD precision for the current coding block.

[0108] (A18) In some embodiments of A1-A17, the method further includes determining a first context for entropy encoding the current coding block in accordance with a determination that the current coding block is coded in a warped motion mode. The method further includes determining a second context for entropy encoding the current coding block in accordance with a determination that the current coding block is coded in a translation motion mode, the second context being different from the first context.

[0109] (A19) In some embodiments of A1-A18, the current coding block is coded in a warped motion mode and a first MVD setting is selected to reconstruct the current coding block. Method 700 includes determining that an alternative coding block of the current image frame is coded in a translation mode, selecting a second MVD setting for the alternative coding block, and reconstructing the alternative coding block based at least in part on the second MVD setting for the alternative coding block. The alternative coding block differs from the current coding block.

[0110] In other aspects, some embodiments include a computing system (e.g., server system 112) including control circuitry (e.g., control circuitry 302) and memory (e.g., memory 314) coupled to the control circuitry, the memory storing one or more instruction sets configured to be executed by the control circuitry, the one or more instruction sets including instructions for performing any of the methods described herein (e.g., A1-A18 above).

[0111] In yet another aspect, some embodiments include a non-transitory computer-readable storage medium storing one or more instruction sets for execution by control circuitry of a computing system, the one or more instruction sets including instructions for performing any of the methods described herein (e.g., A1-A19 above).

[0112] It will also be understood that although terms such as "first," "second," etc. are used herein to describe various elements, these elements are not to be limited by these terms; these terms are used only to distinguish one element from another.

[0113] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the claims. As used in describing the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. The term "and / or," as used herein, will also be understood to refer to and include any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0114] As used herein, the term "if" can be interpreted to mean "when" or "upon" or "in response to determining" or "in accordance with a determination" or "in response to detecting" a stated precondition is true, depending on the context. Similarly, the phrase "if it is determined that [the stated precondition is true]" or "if [the stated precondition is true]" or "when [the stated precondition is true]" can be interpreted to mean "upon determining" or "in response to determining" or "in accordance with a determination" or "upon detecting" or "in response to detecting" a stated precondition is true, depending on the context.

[0115] The foregoing description has been described with reference to specific embodiments for purposes of explanation. However, the exemplary description above is not intended to be exhaustive or to limit the scope of the claims to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described to best explain the principles of operation and practical application, thereby enabling others skilled in the art to utilize them. [Explanation of symbols]

[0116] 100 Communication Systems 102 Source Devices 104 Video Sources 106 Encoder Components 108 Video Bitstream 110 Network 112 Server System 114 Coda Constituents 116 Video Data 120 Electronic Devices 122 Decoder Components 124 display 202 Source Coder 204 Controller 206 Predictor 208 Reference Picture Memory 210 decoder 212 Coding Engine 214 Entropy Coder 216 video sequences 218 Communication Channels 252 buffer memory 254 Parser 256 Loop Filter Unit 258 Scaler / Descaler Unit 260 Motion Compensation Prediction Unit 262 Intra-picture prediction unit 264 Current Picture Memory 266 Reference Picture Memory 268 Aggregators 270 symbols 302 Control circuit 304 Network Interface 306 User Interface 308 Output Devices 310 Input Devices 312 communication bus 314 memory 316 Operating Systems 318 Network Communication Module 320 Coding Module 322 Decoding Module 324 Analysis Module 326 Conversion Module 328 Prediction Module 330 Filter Module 340 Encoding Module 342 Code Module 344 Prediction Module 352 Picture Memory 400 Inter-Predictive Coding Configurations 402 Current Image Frame 404 Current Coding Block 406 Reference Frame 406A First Reference Frame 406B Second Reference Frame 408, 608 reference blocks 408A First Reference Block 408B Second Reference Block 410, 610 motion vectors 410A Motion Vector 410B Motion Vector 412 candidate reference blocks 414 MVD application area 424 Alternative Coding Blocks 450 Inter-Predictive Coding Configuration 602 First Subblock 604A Sub-block motion vector 606A First Reference Sub-Block 608A First Reference Block 608B Second Reference Block 610A First motion vector 610B Second motion vector 612 Refinement Options 620 MVD refinement range 700 methods

Claims

1. A method for decoding video data performed by a decoder, The steps include receiving a video bitstream containing the current coding block within the current image frame, A step of obtaining a syntax element value associated with the current coding block in the current image frame, wherein the syntax element value is signaled before the motion vector difference (MVD) associated with the current coding block, and the syntax element value indicates whether the current coding block is coded in warping motion mode. The steps include determining, based on the syntactic element values, whether the current coding block is coded in warping motion mode or translation motion mode, The steps include selecting a first motion vector difference (MVD) setting for the current coding block, in accordance with the determination that the current coding block is coded in the warping motion mode, A step of selecting a second MVD setting for the current coding block, in accordance with the determination that the current coding block is coded in the translation motion mode, wherein the second MVD setting is different from the first MVD setting. The steps include: rebuilding the current coding block based at least partially on the selected MVD settings for the current coding block; A method that includes this.

2. The method according to claim 1, wherein the first MVD setting includes a first MVD accuracy limit, the second MVD setting includes a second MVD accuracy limit, and the first MVD accuracy limit is lower than the second MVD accuracy limit.

3. The method according to claim 1, wherein the first MVD setting includes a first MVD accuracy limit, the second MVD setting includes a second MVD accuracy limit, and the first MVD accuracy limit is higher than the second MVD accuracy limit.

4. The method according to claim 1, wherein the first MVD setting further includes a first MVD size range, and the second MVD setting includes a second MVD size range different from the first MVD size range.

5. The method according to claim 4, wherein the first MVD size range is greater than the second MVD size range.

6. The current coding block is coded in the warping motion mode, and the first MVD setting is selected to rebuild the current coding block. A step of determining that an alternative coding block of the current image frame is coded in translation mode, wherein the alternative coding block is different from the current coding block. The steps include selecting a second MVD configuration for the aforementioned alternative coding block, The steps include: rebuilding the alternative coding block based at least in part on the second MVD configuration for the alternative coding block; The method according to claim 1, further comprising:

7. The steps include determining that the current coding block has two reference blocks, including a first reference block and a second reference block, A step of determining a first MVD for the first reference block based on either the first MVD setting or the second MVD setting, A step of refining the first MVD for at least the first reference block in order to determine a first refined MVD based on a cost criterion of the difference between the first and second reference blocks, The steps include determining a first motion vector of the current coding block based on the first refined MVD associated with at least the first reference block, The method according to claim 1, further comprising:

8. A step of mirroring the first refined MVD in order to generate an intermediate MVD, A step of scaling an intermediate MVD to generate a second refined MVD based on the ratio of the distances between the first and second reference blocks from the current coding block, A step of determining the second refined MVD for refining the MVD of the second reference block, including The method according to claim 7, further comprising:

9. The method according to claim 7, wherein the difference between the first and second reference blocks includes one of the sum of absolute differences (SAD), the sum of squared errors (SAE), the sum of absolute transformed differences (SATD), and the sum of mean-removed SADs.

10. The step of refining the MVD for at least the first reference block is, The steps include identifying a plurality of refinement options for the first reference block, A step of determining that the difference between the first and second reference blocks corresponding to one of the plurality of refinement options satisfies the cost criterion, The steps include identifying one of the plurality of refinement options as the first refined MVD, The method according to claim 7, further comprising:

11. The step of refining the MVD for at least the first reference block is, A step of determining a plurality of differences between the first and second reference blocks, wherein each difference corresponds to each of the plurality of refinement options of the first reference block, A step of comparing the multiple differences in order to determine whether each difference satisfies the cost criteria, The method according to claim 10, further comprising:

12. The step of determining multiple differences is, A step of determining a subset of differences based on a subset of refinement options, Before comparing the aforementioned multiple differences, the step is to correct a subset of the differences with a difference coefficient of less than 1, The method according to claim 11, further comprising:

13. The step of determining multiple differences is, A step of determining a subset of differences based on a subset of refinement options, Before comparing the multiple differences, the step is to correct a subset of the differences with a difference coefficient greater than 1, The method according to claim 11, further comprising:

14. A computing system, Control circuit and A memory for storing one or more programs configured to be executed by the control circuit, wherein the one or more programs are A memory further including instructions for performing the method according to any one of claims 1 to 13, A computing system equipped with [the following features].

15. The computing system according to claim 14, wherein each of the first and second MVD settings corresponds to the finest supported MVD precision for the current coding block.

16. The computing system according to claim 14, wherein each of the first and second MVD settings corresponds to the coarsest supported MVD precision for the current coding block.

17. The one or more programs mentioned above are In accordance with the determination that the current coding block is coded in the warping motion mode, a first context for entropy encoding the current coding block is determined. In accordance with the determination that the current coding block is coded in the translation motion mode, a second context for entropy encoding the current coding block is determined, wherein the second context is different from the first context. The computing system according to claim 14, further comprising instructions for the following:

18. A computer program for causing a computer to perform the method described in any one of claims 1 to 13.

19. To the aforementioned computer, The current coding block is determined to have two reference blocks, including a first reference block and a second reference block. A first MVD for the first reference block is determined based on either the first MVD setting or the second MVD setting. Based on the cost criterion of the difference between the first and second reference blocks, the first MVD is refined for at least the first reference block in order to determine the first refined MVD. Based on the first refined MVD associated with at least the first reference block, the first motion vector of the current coding block is determined. The computer program according to claim 18, which, in accordance with the determination that the current coding block is coded in the warping motion mode, applies the first motion vector of the current coding block to determine a subblock motion vector for each set of subblocks of the current coding block.

20. To the aforementioned computer, Determine that the first subblock has two reference blocks, including a first reference subblock and a second reference subblock. Based on the cost criterion of the difference between the first and second reference subblocks, the subblock MVD of the first reference subblock is refined in order to determine the refined subblock MVD. The subblock motion vector for the first subblock is updated based on the refined subblock MVD associated with the first reference subblock. The computer program according to claim 19.

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