Geometric partition modes in video coding

Abstract

To provide a geometric partition mode in video coding.SOLUTION: A method of video decoding, comprising receiving, for prediction in a geometric partition mode, a syntax element from a bitstream of encoded video associated with a current coding block partitioned into a first portion and a second portion along a partition edge, and determining a weighted index at a sample position of the current coding block. Determine, for a first motion storage unit of a motion field of the current coding block, a stored motion vector type based on a motion index of the first motion storage unit. The weighted index at the sample position of the current coding block is used as the motion index of the first motion storage unit. The motion field of the current coding block may be stored based on the stored motion vector type determined for the first motion storage unit of the motion field of the current coding block.SELECTED DRAWING: FIG. 1A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. patent application Ser. No. 17 / 091,253, filed November 6, 2020, and entitled "GEOMETRIC PARTITIONING MODE IN VIDEO CODING," which in turn claims the benefit of U.S. provisional patent application Ser. No. 62 / 938,894, filed November 21, 2019, and entitled "SIMPLIFICATION FOR GEO / WEDGE INTER BLOCK." The disclosures of the prior applications are incorporated herein by reference in their entireties.

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

[0003] The discussion of the background art provided herein is intended to provide general information related to the present disclosure, and the inventors' work is not admitted expressly or implicitly as prior art to the present disclosure to the extent described in this background art section, nor in any manner described that would not otherwise be admitted as prior art at the time of filing.

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

[0005] One goal of video encoding and decoding may be to reduce redundancy in an input video signal through compression. Compression can help reduce the aforementioned bandwidth or storage requirements by two or more orders of magnitude, in some cases. Both lossless and lossy compression, as well as combinations thereof, may be used. Lossless compression refers to techniques that allow an exact copy of the original signal to be reconstructed from a compressed version of the original signal. When lossy compression is used, 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 application. For video, lossy compression is widely used. The amount of acceptable distortion depends on the application; for example, users of certain consumer streaming applications may tolerate higher distortion than users of television distribution applications. The achievable compression ratio may reflect that a higher compression ratio can be achieved if a higher degree of distortion is acceptable.

[0006] Video encoders and decoders may utilize techniques from several broad categories, including, for example, motion compensation, transform, quantization, and entropy coding.

[0007] Video codec technology may include a technique known as inter-prediction. For each inter-predicted coding unit (CU), motion parameters include a motion vector, a reference picture index, a reference picture list usage index, and additional information used to generate inter-predicted samples. Motion parameters can be signaled explicitly or implicitly. When a CU is coded using skip mode, the CU is associated with one prediction unit (PU) and has no significant residual coefficients, coded motion vector deltas, or reference picture indexes. A merge mode is specified in which the motion parameters of the current CU are obtained from neighboring CUs, including spatial and temporal candidates and additional schedules introduced, for example, in VVC. Merge mode can be applied to any inter-predicted CU, not just skip mode. An alternative to merge mode is to explicitly transmit motion parameters. The motion vector, the corresponding reference picture index of each reference picture list, the reference picture list usage flag, and other necessary information are explicitly signaled to each CU.

[0008] Some inter-predictive coding tools include enhanced merge prediction, merge mode with motion vector differential (MMVD), advanced motion vector prediction mode (AMVP) with symmetric motion vector differential (MVD) signaling, affine motion compensation prediction, sub-block based temporal motion vector prediction (SbTMVP), adaptive motion vector resolution (AMVR), motion field storage (1 / 16 luma sample MV storage and 8x8 motion field compression), bi-prediction with weighted average (BWA), bidirectional optical flow (BDOF), decoder-side motion vector refinement (DMVR), triangular partitioning mode (TPM), and combined inter and intra prediction (CIIP).

[0009] In some cases, extended merge prediction is used. The merge candidate list is constructed by including five types of candidates in order: (1) spatial MVPs from spatially adjacent CUs, (2) temporal MVPs from collocated CUs, (3) history-based MVPs from a FIFO table, (4) pairwise average MVPs, and (5) zero MVPs.

[0010] The size of the merge list is signaled in the slice header, and the maximum allowed size of the merge list is possibly, for example, 6. For each CU code in merge mode, the index of the best merge candidate is coded using truncated unary binarization (TU). The first bin of the merge index is coded using context, and bypass coding is used for the other bins.

[0011] FIG. 1A illustrates exemplary positions of spatial merge candidates. In some cases, up to four merge candidates can be selected from the candidates in the positions illustrated in FIG. 1A. The selection order is B1, A1, B0, A0, and B2. The candidate in position B2 is considered only if any CU in positions A0, B0, B1, or A1 is unavailable (e.g., the CU in position A0 belongs to another slice or another tile) or is not inter-coded. After the candidate in position A1 is added to the merge candidate list, the addition of the remaining candidates is subject to a redundancy check to ensure that candidates with the same motion information are excluded from the merge candidate list, so as to improve coding efficiency.

[0012] 1B shows candidate pairs considered for redundancy check of spatial merge candidates. To reduce computational complexity, not all possible candidate pairs are considered in the redundancy check. Instead, only pairs connected using arrows in FIG. 1B are considered, and a candidate is added to the merge candidate list only if the corresponding candidates used in the redundancy check do not have the same motion information.

[0013] Figure 1C illustrates motion vector scaling for a temporal merge candidate. In some cases, only one temporal merge candidate can be added to the merge candidate list. Specifically, in the derivation of this temporal merge candidate, a scaled motion vector is derived based on the co-located CUs belonging to the collocated reference pictures. The reference picture list used to derive the co-located CUs is explicitly signaled in the slice header. The scaled motion vector of the temporal merge candidate is obtained as shown by the dotted line in Figure 1C. The scaled motion vector is derived from the motion vector of the co-located CU using picture order count (POC) distances tb and td, where tb is defined as the POC difference between the reference picture of the current picture and the current picture, and td is defined as the POC difference between the reference picture of the co-located picture and the co-located picture. The reference picture index of the temporal merge candidate may be set equal to 0.

[0014] 1D shows exemplary positions of temporal merge candidates. A temporal merge candidate is selected between the CU at position C0 and the CU at position C1. If the CU at position C0 is not available, is not inter-coded, or is outside the current row of the CTU, the CU at position C1 is used. If the CU at position C1 is not used, the CU at position C0 is used to derive the temporal merge candidate. Summary of the Invention [Means for solving the problem]

[0015] Aspects of the present disclosure provide methods and apparatuses for video encoding and decoding. In some examples, the apparatus for video decoding includes a processing circuit. The circuit may be configured to receive syntax elements from a bitstream of coded video associated with a current coding block partitioned into a first portion and a second portion along a partition edge for prediction in a geometric partitioning mode, and to determine a weighted index at a sample position of the current coding block. The weighted index is used to derive mixing weights for mixing two prediction signals corresponding to the first portion and the second portion of the current coding block. The circuit may be further configured to determine a stored motion vector type for a first motion storage unit of a motion field of the current coding block based on a motion index of the first motion storage unit, and to store the motion field of the current coding block based on the stored motion vector type determined for the first motion storage unit of the motion field of the current coding block, using the weighted index at the sample position of the current coding block as the motion index of the first motion storage unit.

[0016] In one embodiment, the sample position of the current coding block for which the weighted index is used as the motion index for the first motion storage unit is a sample position within the first motion storage unit of the motion field of the coding block. In one embodiment, the sample position of the current coding block for which the weighted index is used as the motion index for the first motion storage unit is a sample position adjacent to the center position of the first motion storage unit of the motion field of the coding block. In one embodiment, the first motion storage unit has a size of 4x4 samples, and the sample position of the current coding block for which the weighted index is used as the motion index for the first motion storage unit is a sample position at coordinates (2,2) within the first motion storage unit of the motion field of the coding block.

[0017] In one embodiment, the first motion storage unit has a size of 4x4 samples and stores (x) of the motion field of the current coding block. sb ,y sb ) of the current coding block, and the sample position of the current coding block is at ((x sb ≪2)+2,(y sb ≪2)+2) coordinates, ((x sb ≪2)+2,(y sb The weighted index in the coordinate <<2)+2) is used as the motion index of the first motion storage unit.

[0018] In one embodiment, the circuitry may be further configured to perform a calculation to convert weighted indices at sample positions of the current coding block into mixing weights for mixing two prediction signals, and the conversion may be based on a linear function of the weighted indices at sample positions of the current coding block without using a look-up table.

[0019] In one embodiment, the circuitry determines a value ρ used to shift the partition edge away from the corner of the current coding block. margin determining a weighted index at a sample position of the current coding block based on the value ρ margin may further be configured to vary depending on the width or height of the current coding block and the angle of the partitioning edge.

[0020] In one embodiment, the circuit comprises:

[0021]

number

[0022] where wIdx represents the weighted index, x and y represent coordinates of the sample position of the current coding block, w and h represent the width and height of the current coding block, φ represents the angle of the partition edge, n represents the number of distance quantization steps, and i represents the distance quantization step index.

[0023] In one embodiment, the circuit comprises:

[0024]

number

[0025] where wIdx represents the weighted index, x and y represent coordinates of the sample position of the current coding block, w and h represent the width and height of the current coding block, φ represents the angle of the partition edge, n represents the number of distance quantization steps, and i represents the distance quantization step index.

[0026] In one embodiment, the circuit comprises:

[0027]

number

[0028] where wIdx represents the weighted index, x and y represent coordinates of the sample position of the current coding block, w and h represent the width and height of the current coding block, φ represents the angle of the partition edge, n represents the number of distance quantization steps, and i represents the distance quantization step index.

[0029] In one embodiment, the circuitry is further configured to determine a weighted index at the sample position of the current coding block based on a weighted index of an adjacent sample to the left or above the sample position of the current coding block having a fixed offset value. In one embodiment, the circuitry is further configured to determine a weighted index at the sample position of the current coding block based on a weighted index at a (0,0) coordinate of the current coding block.

[0030] In one embodiment, the circuit comprises:

[0031]

number

[0032] Determine a motion index of a second motion storage unit of the motion field of the current coding block based on: sb and y sb represents the coordinates of the second motion storage unit of the motion field of the current coding block, w and h represent the width and height of the current coding block, φ represents the angle of the partition edge, n represents the number of distance quantization steps, and i represents the distance quantization step index.

[0033] Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the computer to perform any method, or combination thereof, for video decoding.

[0034] Further features, nature and various advantages of the disclosed subject matter will become more apparent from the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0035] [Figure 1A] FIG. 10 illustrates exemplary locations of spatial merge candidates. [Figure 1B] FIG. 10 illustrates exemplary candidate pairs considered for redundancy checking of spatial merge candidates. [Figure 1C] FIG. 10 illustrates an example of motion vector scaling for temporal merge candidates. [Figure 1D] FIG. 10 illustrates exemplary positions for temporal merge candidates. [Figure 2] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system according to one embodiment. [Figure 3] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system according to one embodiment. [Figure 4] FIG. 2 is a schematic diagram of a simplified block diagram of a decoder according to one embodiment. [Figure 5] FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment. [Figure 6] FIG. 4 is a block diagram of an encoder according to another embodiment. [Figure 7] FIG. 10 is a block diagram of a decoder according to another embodiment. [Figure 8A] FIG. 1 illustrates an example triangulation scheme according to some embodiments. [Figure 8B] FIG. 1 illustrates an example triangulation scheme according to some embodiments. [Figure 9] FIG. 10 illustrates uni-predictive motion vector selection for triangular partitioning modes according to some embodiments. [Figure 10A] FIG. 10 illustrates an exemplary weighting map for luma according to some embodiments. [Figure 10B] FIG. 10 illustrates an exemplary weighting map for chroma according to some embodiments. [Figure 11] FIG. 10 illustrates an exemplary geometric partitioning mode according to some embodiments of the present disclosure. [Figure 12] 1 is a flowchart outlining an exemplary process according to one embodiment. [Figure 13] FIG. 1 is a schematic diagram of a computer system according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0036] I. Video Encoder and Video Decoder FIG. 2 illustrates a simplified block diagram of a communication system (200) according to one embodiment of the present disclosure. The communication system (200) includes multiple terminal devices that can communicate with each other, for example, via a network (250). For example, the communication system (200) includes a first pair of terminal devices (210) and (220) interconnected via the network (250). In the example of FIG. 2, the first pair of terminal devices (210) and (220) perform unidirectional data transmission. For example, the terminal device (210) may encode video data (e.g., a stream of video pictures captured by the terminal device (210)) for transmission to another terminal device (220) via the network (250). The encoded video data may be transmitted in the form of one or more encoded video bitstreams. The terminal device (220) may receive the encoded video data from the network (250), decode the encoded video data to reconstruct the video pictures, and display the video pictures in accordance with the reconstructed video data. One-way data transmission may be common, such as in media serving applications.

[0037] In another example, the communication system (200) includes a second pair of terminal devices (230) and (240) that perform bidirectional transmission of encoded video data, such as may occur during a video conference. To transmit data bidirectionally, in one example, each of the terminal devices (230) and (240) can encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission to the other of the terminal devices (230) and (240) over the network (250). Each of the terminal devices (230) and (240) can also receive the encoded video data transmitted by the other of the terminal devices (230) and (240), decode the encoded video data to recover the video pictures, and display the video pictures on an accessible display device in response to the recovered video data.

[0038] In the example of FIG. 2 , terminal devices 210, 220, 230, and 240 may be depicted as a server, a personal computer, and a smartphone, although the principles of the present disclosure need not be so limited. Embodiments of the present disclosure find application with laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. Network 250 represents any number of networks that convey encoded video data between terminal devices 210, 220, 230, and 240, including, for example, wired communication (cable) networks and / or wireless communication networks. Communication network 250 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. For purposes of this description, the architecture of network 250 and the topology of network 250 may be irrelevant to the operation of the present disclosure, unless otherwise described herein.

[0039] 3 illustrates the placement of a video encoder and a video decoder in a streaming environment as an example of an application of the disclosed subject matter, which may be equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, and storing compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0040] The streaming system may include a capture subsystem (313), which may include a video source (301), such as a digital camera, that generates a stream of uncompressed video pictures (302). In one example, the stream of video pictures (302) includes samples captured by the digital camera. The stream of video pictures (302), depicted as a thick line to emphasize its high data volume compared to the encoded video data (304) (or encoded video bitstream), may be processed by an electronic device (320) that includes a video encoder (303) connected to the video source (301). The video encoder (303) may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The encoded video data (304) (or encoded video bitstream (304)), depicted as a thin line to emphasize its low data volume compared to the stream of video pictures (302), may be stored on a streaming server (305) for future use. One or more streaming client subsystems, such as the client subsystems (306) and (308) of Figure 3, can access the streaming server (305) to obtain copies (307) and (309) of the encoded video data (304). The client subsystem (306) may include a video decoder (310), for example, within an electronic device (330). The video decoder (310) decodes the input copy (307) of the encoded video data and creates an output stream of video pictures (311) that can be rendered on a display (312) (e.g., a display screen) or other rendering device (not shown). In some streaming systems, the encoded video data (304), (307), and (309) (e.g., a video bitstream) can be encoded according to a particular video encoding / compression standard. Examples of these standards include ITU-T Recommendation H.265. In one example, a video encoding standard under development is informally known as Versatile Video Coding (VVC).The disclosed subject matter may be used in the context of a VVC.

[0041] It should be noted that electronic devices 320 and 330 may include other components (not shown). For example, electronic device 320 may include a video decoder (not shown), and electronic device 330 may also include a video encoder (not shown).

[0042] 4 shows a block diagram of a video decoder (410) according to one embodiment of the present disclosure. The video decoder (410) may be included in an electronic device (430). The electronic device (430) may include a receiver (431) (e.g., receiving circuitry). The video decoder (410) may be used in place of the video decoder (310) in the example of FIG. 3.

[0043] The receiver (431) may receive one or more coded video sequences to be decoded by the video decoder (410), in the same or another embodiment, one coded video sequence at a time, where the decoding of each coded video sequence is independent of the other coded video sequences. The coded video sequences may be received from a channel (401), which may be a hardware / software link to a storage device that stores the coded video data. The receiver (431) may receive the coded video data along with other data, such as coded audio data and / or auxiliary data streams, which may be forwarded to elements (not shown) that use the respective data. The receiver (431) may separate the coded video sequences from other data. To combat network jitter, a buffer memory (415) may be connected between the receiver (431) and the entropy decoder / parser (420) (hereinafter, parser (420)). In certain applications, the buffer memory (415) is part of the video decoder (410). In other applications, it may be external to the video decoder (410) (not shown). In still other applications, there may be a buffer memory (not shown) external to the video decoder (410), for example, to combat network jitter, and another buffer memory (415) internal to the video decoder (410), for example, to handle playback timing. If the receiver (431) is receiving data from a storage / transmission device with sufficient bandwidth and controllability, or from an asynchronous network, the buffer memory (415) may not be necessary or may be small. For use with best-effort packet networks such as the Internet, the buffer memory (415) may be required, may be relatively large, advantageously of adaptive size, and may be implemented at least in part in an operating system or similar element (not shown) external to the video decoder (410).

[0044] The video decoder (410) may include a parser (420) to reconstruct symbols (421) from the encoded video sequence. These symbol categories include information used to manage the operation of the video decoder (410) and may include information for controlling a rendering device, such as a rendering device (412) (e.g., a display screen) that is not an integral part of the electronic device (430) but may be connected to the electronic device (430), as shown in FIG. 4. The control information for the rendering device may be in the form of a parameter set fragment (not shown) of a supplemental enhancement information (SEI message) or video usability information (VUI). The parser (420) may parse / entropy decode the received encoded video sequence. The encoding of the encoded video sequence may be according to a video coding technique or standard and may be according to various principles, including variable length coding, Huffman coding, context-dependent arithmetic coding, or context-dependent arithmetic coding. The parser (420) may extract, from the coded video sequence, a set of subgroup parameters for at least one of the subgroups of pixels in a video decoder based on at least one parameter corresponding to the group. The subgroups may include groups of pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The parser (420) may also extract information from the coded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, etc.

[0045] The parser (420) may perform entropy decoding / entropy analysis operations on the video sequence received from the buffer memory (415) to create symbols (421).

[0046] The reconstruction of the symbols (421) may involve several different units, depending on the type of coded video picture or portion thereof (e.g., inter-picture and intra-picture, inter-block and intra-block), and other factors. Which units participate and how can be controlled by subgroup control information parsed from the coded video sequence by the parser (420). The flow of such subgroup control information between the parser (420) and the following units is not shown for clarity.

[0047] Beyond the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units, as described below. In an actual implementation operating under commercial constraints, many of these units 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, a conceptual subdivision into the following functional units is appropriate:

[0048] The first unit is a scalar / inverse transform unit (451), which receives quantized transform coefficients as symbols (421) from the parser (420), as well as control information, such as which transform to use, block size, quantization coefficients, quantization scaling matrices, etc. The scalar / inverse transform unit (451) may output blocks containing sample values, which may be input to an aggregator (455).

[0049] In some cases, the output samples of the scaler / inverse transform unit (451) may relate to intra-coded blocks, i.e., blocks that do not use prediction information from a previously reconstructed picture but can use prediction information from a previously reconstructed portion of the current picture. Such prediction information may be provided by an intra-picture prediction unit (452). In some cases, the intra-picture prediction unit (452) generates blocks of the same size and shape as the block being reconstructed using surrounding, already reconstructed information retrieved from a current picture buffer (458). The current picture buffer (458), for example, buffers a partially reconstructed and / or fully reconstructed current picture. The aggregator (455) may optionally add the prediction information generated by the intra-prediction unit (452) to the output sample information provided by the scaler / inverse transform unit (451) on a sample-by-sample basis.

[0050] In other cases, the output samples of the scalar / inverse transform unit (451) may relate to a block that may be inter-coded and motion-compensated. In such cases, the motion compensation prediction unit (453) may access a reference picture memory (457) to retrieve samples used for prediction. After motion-compensating the retrieved samples according to the symbols (421) associated with the block, these samples may be added by an aggregator (455) to the output of the scalar / inverse transform unit (451) (in this case, referred to as residual samples or residual signals) to generate output sample information. The addresses in the reference picture memory (457) from which the motion compensation prediction unit (453) retrieves prediction samples may be controlled by motion vectors available to the motion compensation prediction unit (453), for example, in the form of symbols (421) that may have X, Y, and reference picture components. Motion compensation may also include interpolation of sample values ​​retrieved from the reference picture memory (457) when sub-sample accurate motion vectors are used, motion vector prediction mechanisms, and the like.

[0051] The output samples of the aggregator (455) may be subjected to various loop filtering techniques in a loop filter unit (456). Video compression techniques may include in-loop filtering techniques controlled by parameters contained in the coded video sequence (also called the coded video bitstream) and made available to the loop filter unit (456) as symbols (421) from the parser (420), which may be responsive to meta-information obtained while decoding a previous portion (in decoding order) of the coded picture or coded video sequence, as well as to previously reconstructed loop-filtered sample values.

[0052] The output of the loop filter unit (456) may be a sample stream that may be output to a rendering device (412) or stored in a reference picture memory (457) 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. For example, once the coded picture corresponding to the current picture is fully reconstructed and the coded picture is identified as a reference picture (e.g., by the parser (420)), the current picture buffer (458) may become part of the reference picture memory (457), and a new current picture buffer may be relocated before beginning reconstruction of a subsequent coded picture.

[0054] The video decoder (410) may perform decoding operations according to a predetermined video compression technique in a standard such as ITU-T Recommendation H.265. An encoded video sequence may conform to a syntax specified by a video compression technique or standard, which is used to mean that the encoded video sequence conforms to both the syntax of the video compression technique or standard and a profile documented in the video compression technique or standard. Specifically, a profile may select certain tools from all tools available in the video compression technique or standard as the only tools usable under that profile. Compliance may also require that the complexity of the encoded video sequence be within a range defined by the level of the video compression technique or standard. In some cases, the level limits the maximum picture size, maximum frame rate, maximum reconstruction sample rate (e.g., measured in megasamples per second), maximum reference picture size, etc. The limits set by the levels may in some cases be further restricted by the hypothetical reference decoder (HRD) specifications and metadata for HRD buffer management signaled in the coded video sequence.

[0055] In one embodiment, the receiver (431) may receive additional (redundant) data with the encoded video. The additional data may be included as part of the encoded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0056] 5 shows a block diagram of a video encoder (503) according to one embodiment of the present disclosure. The video encoder (503) is included in an electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) may be used in place of the video encoder (303) in the example of FIG. 3.

[0057] The video encoder (503) may receive video samples from a video source (501) (not part of the electronic device (520) in the example of FIG. 5) that may capture video images to be encoded by the video encoder (503). In another example, the video source (501) is part of the electronic device (520).

[0058] The video source (501) may provide a source video sequence to be encoded by the video encoder (503) in the form of a digital video sample stream, which may be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, ...), and any suitable sampling structure (e.g., Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the video source (501) may be a storage device that stores prepared video. In a video conferencing system, the video source (501) may be a camera that captures local image information as a video sequence. The video data may be provided as multiple individual pictures that, when viewed sequentially, give the appearance of motion. The pictures themselves may be organized as a spatial array of pixels, each of which may contain one or more samples depending on the sampling structure, color space, etc., in use. Those skilled in the art will readily understand the relationship between pixels and samples. The following discussion will focus on samples.

[0059] According to one embodiment, the video encoder (503) may encode and compress pictures of a source video sequence into an encoded video sequence (543) in real time or under any other time constraints required by the application. Enforcing an appropriate encoding rate is one function of the controller (550). In some embodiments, the controller (550) controls and is operatively connected to other functional units, as described below. This connection is not shown for clarity. Parameters set by the controller (550) may include rate control-related parameters (picture skip, quantizer, lambda value for rate-distortion optimization techniques, ...), picture size, group of pictures (GOP) layout, maximum motion vector search area, etc. The controller (550) may also be configured with other appropriate functions associated with the video encoder (503) optimized for a particular system design.

[0060] In some embodiments, the video encoder (503) is configured to operate in an encoding loop. As an overly simplified explanation, in one example, the encoding loop may include a source encoder (530) and a (local) decoder (533) embedded in the video encoder (503) (e.g., responsible for generating symbols, such as a symbol stream, based on an input picture to be encoded and a reference picture). The decoder (533) reconstructs the symbols to create sample data in a manner similar to that of the (remote) decoder (because in the video compression techniques contemplated by the disclosed subject matter, any compression between the symbols and the encoded video bitstream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (534). Because decoding of the symbol stream yields bit-accurate results regardless of the location of the decoder (local or remote), the contents of the reference picture memory (534) are also bit-accurate between the local and remote encoders. In other words, what the encoder's predictor "sees" as a reference picture are the exact same sample values ​​that the decoder would "see" if it were to use prediction during decoding. This basic principle of reference picture synchrony (the resulting drift if synchrony cannot be maintained, e.g., due to channel errors) is also used in several related technologies.

[0061] The operation of the "local" decoder (533) may be identical to the operation of a "remote" decoder, such as the video decoder (410) already described in detail above in connection with Figure 4. However, and referring briefly to Figure 4 as well, because symbols are available and the encoding / decoding of symbols into the encoded video sequence by the entropy coder (545) and parser (420) may be lossless, the entropy decoding portion of the video decoder (410), including the buffer memory (415), and the parser (420), may not be fully implemented in the local decoder (533).

[0062] A possible observation from the discussion so far is that any decoder technology, other than analysis / entropy decoding, present in a decoder must also be present in a corresponding encoder in substantially identical functional form. For this reason, the disclosed subject matter focuses on decoder operation. A description of the encoder technology can be omitted, since it is the inverse of the decoder technology described generically. Only in certain areas is more detailed explanation required, which is provided below.

[0063] During operation, in some examples, the source encoder (530) may perform motion-compensated predictive coding, which predictively codes an input picture with reference to one or more previously coded pictures from a video sequence designated as “reference pictures.” In this manner, the encoding engine (532) encodes differences between pixel blocks of the input picture and pixel blocks of reference pictures that may be selected as predictive references for the input picture.

[0064] The local video decoder (533) may decode the coded video data of pictures that may be designated as reference pictures based on symbols created by the source encoder (530). The operation of the coding engine (532) may advantageously be a lossy process. When the coded video data is decoded by a video decoder (not shown in FIG. 5), the reconstructed video sequence may be a replica of the source video sequence, typically with some errors. The local video decoder (533) may replicate the decoding process performed by the video decoder on the reference pictures and store the reconstructed reference pictures in a reference picture cache (534). In this way, the video encoder (503) may locally store copies of reconstructed reference pictures that share common content (in the absence of transmission errors) with the reconstructed reference pictures obtained by the far-end video decoder.

[0065] The predictor (535) may perform a predictive search for the coding engine (532). That is, for a new picture to be coded, the predictor (535) may search the reference picture memory (534) for sample data (as candidate reference pixel blocks) or specific metadata, such as reference picture motion vectors and block shapes, that may serve as suitable prediction references for the new picture. The predictor (535) may operate on a sample block by pixel block basis to find suitable prediction references. In some cases, as determined by the search results obtained by the predictor (535), the input picture may have prediction references drawn from multiple reference pictures stored in the reference picture memory (534).

[0066] The controller (550) may manage the encoding operations of the source encoder (530), including, for example, setting the parameters and subgroup parameters used to encode the video data.

[0067] The output of all the aforementioned functional units may be subjected to entropy coding in an entropy coder (545), which converts the symbols produced by the various functional units into an encoded video sequence by losslessly compressing the symbols according to techniques such as Huffman coding, variable length coding, or arithmetic coding.

[0068] The transmitter (540) may buffer the encoded video sequence produced by the entropy encoder (545) and prepare it for transmission over a communication channel (560), which may be a hardware / software link to a storage device that stores the encoded video data. The transmitter (540) may merge the encoded video data from the video encoder (503) with other data to be transmitted, such as encoded audio data and / or auxiliary data streams (sources not shown).

[0069] The controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a particular coded picture type to each coded picture, which may affect the coding technique that may be applied to the respective picture. For example, pictures are often assigned as one of the following picture types:

[0070] An intra-picture (I-picture) may be a picture that can be coded and decoded without using other pictures in a sequence as a source of prediction. Some video codecs allow different types of intra-pictures, including, for example, independent decoding refresh ("IDR") pictures. Those skilled in the art will recognize these variations of I-pictures and their respective applications and characteristics.

[0071] A predicted picture (P picture) may be a picture that may be coded and decoded using intra- or inter-prediction, which uses at most one motion vector and one reference index to predict the sample values ​​of each block.

[0072] A bidirectionally predicted picture (B picture) may be a picture that may be coded and decoded using intra- or inter-prediction, which uses up to two motion vectors and two reference indices to predict the sample values ​​of each block. Similarly, a multi-predicted picture may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0073] A source picture is generally spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks as determined by the coding assignment applied to the block's respective picture. For example, blocks of an I-picture may be non-predictively coded or predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). Pixel blocks of a P-picture may be predictively coded via spatial or temporal prediction with reference to one previously coded reference picture. Blocks of a B-picture may be predictively coded via spatial or temporal prediction with reference to one or two previously coded reference pictures.

[0074] The video encoder (503) may perform encoding operations according to a predetermined video encoding technique or standard, such as ITU-T Recommendation H.265. In doing so, the video encoder (503) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancy in the input video sequence. Thus, the encoded video data may conform to a syntax specified by the video encoding technique or standard being used.

[0075] In one embodiment, the transmitter (540) may transmit additional data along with the encoded video. The source encoder (530) may include such data as part of the encoded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, SEI messages, fragments of sets of VUI parameters, etc.

[0076] Video may be captured in time sequence as multiple source pictures (video pictures). Intra-picture prediction (often abbreviated as intra-prediction) exploits spatial correlation within a given picture, while inter-picture prediction exploits inter-picture (temporal or other) correlation. In one example, a particular picture being coded / decoded, called the current picture, is partitioned into blocks. If a block of the current picture is similar to a reference block of a previously coded and still buffered reference picture within the video, the block of the current picture can be coded by a vector called a motion vector. The motion vector points to a reference block of the reference picture and may have a third dimension that identifies the reference picture if multiple reference pictures are used.

[0077] In some embodiments, inter-picture prediction may use a bi-prediction technique. According to the bi-prediction technique, two reference pictures, such as a first reference picture and a second reference picture, are used, both of which are before the current picture in the video in decoding order (but may be in the past and future, respectively, in display order). A block of the current picture may be coded by a first motion vector pointing to a first reference block of the first reference picture and a second motion vector pointing to a second reference block of the second reference picture. A block may be predicted by a combination of the first reference block and the second reference block.

[0078] Furthermore, merge mode techniques can be used in inter-picture prediction to improve coding efficiency.

[0079] According to some embodiments of the present disclosure, prediction, such as inter-picture prediction and intra-picture prediction, is performed on a block-by-block basis. For example, according to the HEVC standard, pictures in a sequence of video pictures are partitioned into coding tree units (CTUs) for compression, and the CTUs within a picture have the same size, such as 64x64 pixels, 32x32 pixels, or 16x16 pixels. Generally, a CTU includes three coding tree blocks (CTBs), one luma CTB and two chroma CTBs. Each CTU can be recursively quadtree partitioned into one or more CUs. For example, a 64x64 pixel CTU can be partitioned into one CU of 64x64 pixels, four CUs of 32x32 pixels, or 16 CUs of 16x16 pixels. In one example, each CU is analyzed to determine a prediction type for the CU, such as an inter-prediction type or an intra-prediction type. The CU is then partitioned into one or more prediction units (PUs) according to temporal and / or spatial predictability. Generally, each PU includes a luma prediction block (PB) and two chroma PBs. In one embodiment, prediction operations in encoding (encoding / decoding) are performed in units of prediction blocks. Using a luma prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values ​​(e.g., luma values), such as 8x8 pixels, 16x16 pixels, 8x16 pixels, 16x8 pixels, etc.

[0080] 6 shows a diagram of a video encoder (603) according to another embodiment of the present disclosure. The video encoder (603) is configured to receive a processed block of sample values ​​(e.g., a predictive block) of a current video picture in a sequence of video pictures and to encode the processed block into an encoded picture that is part of the encoded video sequence. In one example, the video encoder (603) is used in place of the example video encoder (303) of FIG. 3.

[0081] In an HEVC example, the video encoder (603) receives a matrix of sample values ​​for a processing block, such as a predicted block of 8x8 samples. The video encoder (603) determines whether the processing block is optimally coded using intra-mode, inter-mode, or bi-predictive mode, e.g., using rate-distortion optimization. If the processing block is to be coded in intra-mode, the video encoder (603) may use intra-prediction techniques to code the processing block into a coded picture. If the processing block is to be coded in inter-mode or bi-predictive mode, the video encoder (603) may use inter-prediction or bi-prediction techniques, respectively, to code the processing block into a coded picture. In certain video coding techniques, the merge mode may be an inter-picture prediction sub-mode, in which a motion vector is derived from one or more motion vector predictors without the aid of coded motion vector components outside the predictors. In certain other video coding techniques, there may be motion vector components applicable to the current block. In one example, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining the mode of the processing blocks.

[0082] In the example of Figure 6, the video encoder (603) includes an inter-encoder (630), an intra-encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), an overall controller (621), and an entropy encoder (625), connected to each other as shown in Figure 6.

[0083] The inter-encoder (630) is configured to receive samples of a current block (e.g., a processing block), compare this block with one or more reference blocks of a reference picture (e.g., blocks of a previous picture and a subsequent picture), generate inter-prediction information (e.g., an inter-coding technique, a motion vector, an explanation for redundant information by merge mode information), and calculate an inter-prediction result (e.g., a predicted block) based on the inter-prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture that is decoded based on coded video information.

[0084] The intra encoder (622) is configured to receive samples of a current block (e.g., a processing block), optionally compare the block with previously coded blocks in the same picture, generate quantized coefficients after transformation, and optionally also generate intra prediction information (e.g., intra prediction direction information according to one or more intra coding techniques). In one example, the intra encoder (622) calculates an intra prediction result (e.g., a prediction block) based on the intra prediction information and a reference block in the same picture.

[0085] The overall controller (621) is configured to determine overall control data and control other components of the video encoder (603) based on the overall control data. In one example, the overall controller (621) determines the mode of the block and provides a control signal to the switch (626) based on the mode. For example, if the mode is intra mode, the overall controller (621) controls the switch (626) to select an intra mode result to be used by the residual calculator (623) and controls the entropy encoder (625) to select intra prediction information and include the intra prediction information in the bitstream. If the mode is inter mode, the overall controller (621) controls the switch (626) to select an inter prediction result to be used by the residual calculator (623) and controls the entropy encoder (625) to select inter prediction information and include the inter prediction information in the bitstream.

[0086] The residual calculator (623) is configured to calculate the difference (residual data) between the received block and a prediction result selected from the intra-encoder (622) or inter-encoder (630). The residual encoder (624) is configured to operate on the residual data to encode the residual data to generate transform coefficients. In one example, the residual encoder (624) is configured to transform the residual data from the spatial domain to the frequency domain to generate transform coefficients. The transform coefficients are then subjected to a quantization process to obtain quantized transform coefficients. In various embodiments, the video encoder (603) also includes a residual decoder (628). The residual decoder (628) is configured to perform an inverse transform and generate decoded residual data. The decoded residual data can be used by the intra-encoder (622) and inter-encoder (630), as appropriate. For example, the inter-encoder (630) may generate decoded blocks based on the decoded residual data and inter-prediction information, and the intra-encoder (622) may generate decoded blocks based on the decoded residual data and intra-prediction information. In some examples, the decoded blocks are processed appropriately to generate decoded pictures, which may be buffered in a memory circuit (not shown) and used as reference pictures.

[0087] The entropy encoder (625) is configured to format the bitstream to include the encoded block. The entropy encoder (625) is configured to include various information according to an appropriate standard, such as the HEVC standard. In one example, the entropy encoder (625) is configured to include global control data, selected prediction information (e.g., intra-prediction information or inter-prediction information), residual information, and other appropriate information in the bitstream. It should be noted that, according to the disclosed subject matter, when encoding a block in a merged sub-mode of either an inter mode or a bi-prediction mode, residual information is not present.

[0088] 7 shows a diagram of a video decoder (710) according to another embodiment of the present disclosure. The video decoder (710) is configured to receive coded pictures that are part of a coded video sequence and decode the coded pictures to generate reconstructed pictures. In one example, the video decoder (710) is used in place of the video decoder (310) of the example of FIG. 3.

[0089] In the example of Figure 7, the video decoder (710) includes an entropy decoder (771), an inter-decoder (780), a residual decoder (773), a reconstruction module (774), and an intra-decoder (772), connected together as shown in Figure 7.

[0090] The entropy decoder (771) may be configured to reconstruct, from the coded picture, certain symbols that represent the syntax elements of which the coded picture is composed. Such symbols may include, for example, the mode in which the block is coded (e.g., intra mode, inter mode, bi-prediction mode, inter mode of merged submode and bi-prediction mode of merged submode, or another submode, etc.), prediction information (e.g., intra prediction information or inter prediction information, etc.) that can identify certain samples or metadata that the intra decoder (772) or inter decoder (780), respectively, will use for prediction, and residual information, for example, in the form of quantized transform coefficients. In one example, if the prediction mode is an inter prediction mode or a bi-prediction mode, the inter prediction information is provided to the inter decoder (780), and if the prediction type is an intra prediction type, the intra prediction information is provided to the intra decoder (772). The residual information may be subjected to inverse quantization, and the residual information is provided to the residual decoder (773).

[0091] The inter decoder (780) is configured to receive the inter prediction information and generate an inter prediction result based on the inter prediction information.

[0092] The intra decoder (772) is configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0093] The residual decoder (773) is configured to perform inverse quantization to extract dequantized transform coefficients and process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (773) may also require certain control information (to include quantizer parameters (QP)), which may be provided by the entropy decoder (771) (data path not shown, as there may only be a low amount of control information).

[0094] The reconstruction module (774) is configured to combine, in the spatial domain, the residual as output by the residual decoder (773) and the prediction result (as output by the inter-prediction module or the intra-prediction module, as the case may be), to form a reconstructed block, which may be part of a reconstructed picture, and the resulting reconstructed picture may be part of the reconstructed video. It should be noted that other appropriate operations, such as a deblocking operation, may be performed to improve visual quality.

[0095] It should be noted that the video encoders (303), (503), and (603) and the video decoders (310), (410), and (710) may be implemented using any suitable technology. In one embodiment, the video encoders (303), (503), and (603) and the video decoders (310), (410), and (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoders (303), (503), and (603) and the video decoders (310), (410), and (710) may be implemented using one or more processors executing software instructions.

[0096] II. Triangular Partitioning Mode (TPM) for Inter Prediction In some cases, TPM can be supported for inter prediction. TPM is only applicable to CUs of 8x8 or larger. TPM can be signaled using a CU-level flag as one type of merge mode along with other merge modes such as normal merge mode, MMVD mode, CIIP mode, and sub-block merge mode.

[0097] When TPM is used, a CU can be evenly divided into two triangular-shaped partitions using either diagonal or anti-diagonal partitioning, as shown in Figures 8A and 8B. Each triangular partition in a CU can be inter-predicted using its own motion parameters. Only uni-prediction is allowed for each partition; that is, each partition has one motion vector and one reference index. Uni-prediction motion constraints are applied to ensure that the triangular partitions are the same as conventional bi-prediction; that is, only two motion-compensated predictions are required for each CU. The uni-prediction motion for each partition may be derived using the process described in Figures 1A to 1D.

[0098] When a TPM is used for the current CU, a flag indicating the TPM direction (diagonal or anti-diagonal) and two merge indices (one per partition) can be further signaled. The maximum TPM candidate size can be explicitly signaled at the slice level, and syntactic binarization of the TPM merge indices can be specified. After predicting each of the triangle partitions, the sample values ​​along the diagonal or anti-diagonal edges can be adjusted using a blending process with adaptive weights. After deriving the prediction signal for the entire CU, further transformation and quantization processes can be applied to the entire CU, as in other prediction modes. Finally, the motion field of the CU predicted using the TPM may be stored.

[0099] In some cases, the TPM cannot be used in combination with the sub-block transform (SBT), i.e., if the signaled triangle mode is equal to 1, cu_sbt_flag is inferred to be 0 without signaling.

[0100] II.1 Uni-prediction candidate list construction The uni-predictive candidate list may be derived directly from the merge candidate list constructed according to the extended merge prediction process. Let the index of a uni-predictive motion in the triangular uni-predictive candidate list be denoted as N. The LX motion vector of the Nth extended merge candidate, where X is equal to the parity of N, is used as the Nth uni-predictive motion vector for the TPM. These motion vectors are marked with an "X" in Figure 9. If there is no corresponding LX motion vector for the N extended merge candidates, the L(1-X) motion vectors of the same candidate are used instead as uni-predictive motion vectors for the TPM.

[0101] II.2 Blending along triangulation edges After predicting each triangle segment using its own motion parameters, a blending process may be applied to the two predicted signals to derive samples around the diagonal or anti-diagonal edges. As shown in Figures 10A and 10B, the following weighting values ​​are used in the blending process: {7 / 8, 6 / 8, 5 / 8, 4 / 8, 3 / 8, 2 / 8, 1 / 8} for luma and {6 / 8, 4 / 8, 2 / 8} for chroma.

[0102] In some cases, motion vectors for CUs coded in the TPM can be generated using the following process: If Mv1 and Mv2 are from different reference picture lists (e.g., one from L0 and the other from L1), Mv1 and Mv2 are simply combined to form a bi-predictive motion vector. Otherwise, if Mv1 and Mv2 are from the same list, only the uni-predictive motion Mv2 is stored.

[0103] III. Geometric Merge Mode (GEO) The techniques related to Geometric Merge Mode (GEO) are explained in (i)-(iii), which are (i) Han Gao, Semih Esenlik, Elena Alshina, Anand Meher Kotra, Biao Wang, Max Blaser, Johannes Sauer, "CE4:CE4-1.1, CE4-1.2 and CE4-1.14:Geometric Merge Mode (GEO)", JVET-P0068, Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 16th Meeting: Geneva, CH, October 1-11, 2019, and (ii) Han Gao, Semih Esenlik, Elena Alshina, Anand Meher Kotra, Biao Wang, Max Blaser, Johannes Sauer, "Simplified GEO without multiplication and "minimum blending mask storage", JVET-P0884, Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11,16th Meeting: Geneva, CH, October 1-11, 2019, (iii) Kevin Reuze1, Chun-Chi Chen2, Han Huang3, Wei-Jung Chien, Vadim Seregin, Marta Karczewicz, Ru-Ling Liao4, Jie Chen5, Yan Ye, Jiancong Luo, Max Blaser, Johannes Sauer, ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 16th Meeting: Geneva, CH, October 1-11, 2019. Documents JVET-P0068, JVET-P0884, and JVET-P0085 are incorporated herein by reference.

[0104] Geometric Merge Mode (GEO), also known as Geometric Partitioning Mode (GPM), can support multiple different partitioning schemes. The partitioning schemes can be defined by angles and edges. For example, 140 different partitioning schemes can be distinguished by 32 angles (quantized between 0 and 360 degrees, equally spaced 11.25 degrees apart) and 5 edges relative to the center of the CU.

[0105] Figure 11 shows an exemplary GEO. In Figure 11, the angle φ i represents a quantized angle between 0 and 360 degrees, and the distance offset ρ i is the maximum distance ρ max represents the quantized offset of max The value of ρ may be derived geometrically by Equation 5, with either w or h equal to 8 and scaled with the short edge length log2 scaled. The variables h and w represent the height and width of the current block. When φ is equal to 0°, ρ max is equal to w / 2. When φ is equal to 90°, ρ max is equal to h / 2. In Equation 1, ρ margin =1.0 is to prevent the split boundary from getting too close to the corners of the current block.

[0106]

number

[0107] Each partition mode (i.e., pair of angle index and edge index) in GEO can be assigned a pixel-adaptive weight table for blending samples in the two partitioned parts. The weight value of a sample may range from 0 to 8, for example, and may be determined by the L2 distance from the pixel's center position to the edge. When weight values ​​are assigned, a unit increase constraint may be observed. For example, when a small weight value is assigned to a GEO partition, a large complementary weight value is assigned to the other partition, up to a total of 8 weight values.

[0108] IV. Weighted Sample Prediction Processing for GEO IV.1 Mixed weight calculation In GEO, the final sample predictor P B may be derived according to Equation 6 using two 3-bit blending masks (ie, weights or weighting factors) W0 and W1 and two predictors P0 and P1. P B =(W0P0+W1P1+4)≫3 (Formula 6)

[0109] The blending masks W0 and W1 may be derived from a lookup table based on their weighting indices. The blending weighting indices (also called blending weights in some contexts) may be derived based on the distance between the sample location (x,y) and the splitting boundary, as shown in Equation 7.

[0110]

number

[0111] In Equation 10, n represents the total distance quantization step, i represents the distance step index of the GEO with angle φ, and i <nである。

[0112] Finally, the sample blending masks W0 and W1 (or weights) may be set using Table 3, represented as GeoFilter, as shown in Equation 11.

[0113]

number

[0114] An exemplary weighted sample prediction process is described below. Inputs to the weighted sample prediction process include two variables nCbW and nCbH that specify the width and height of the current coding block, two (nCbW) x (nCbH) arrays predSamplesLA and predSamplesLB, a variable angleIdx that specifies the angle index of the geometric partition, a variable distanceIdx that specifies the distance idx of the geometric partition, and a variable cIdx that specifies the color component index. Outputs of the weighted sample prediction process include a (nCbW) x (nCbH) array pbSamples of predicted sample values, and a (nCbW≫2) x (nCbH≫2) array motionIdx.

[0115] The variable bitDepth may be derived as follows: if cIdx=0, then bitDepth=BitDepthY, and if cIdx=0, then bitDepth=BitDepthC.

[0116] The variables shift1=Max(5,17-bitDepth) and offset1=1<<(shift1-1).

[0117] The weighting array for luma, sampleWeightL[x][y], and the weighting array for chroma, sampleWeightC[x][y], with x=0..nCbW-1 and y=0..nCbH-1, may be derived as follows:

[0118] The variables wIdx = log2(nCbW), and hIdx = log2(nCbH).

[0119] Variable whRatio=(wIdx≧hIdx)?wIdx-hIdx:hIdx-wIdx,scaleIdx=(wIdx≧hIdx)?hIdx-3:wIdx-3.

[0120] The variables displacementX=angleIdx, and displacementY=(displacementX+8)%32.

[0121] Variable angleN=(wIdx≧hIdx)?(angleIdx≫3&1)?angleIdx%8:8-angleIdx%8:(angleIdx≫3&1)?8-angleIdx%8:angleIdx%8.

[0122] The variable rho may be set to the following values ​​using the lookup tables designated as stepDis and Dis as specified in Tables 1 and 2: rho=distanceIdx*(stepDis[whRatio][angleN]≪scaleIdx)+(Dis[displacementX]≪wIdx)+(Dis[displacementY]≪hIdx)

[0123] The variables weightIdx and weightIdxAbs can be calculated using lookup table 2 with x=0..nCbW-1 and y=0...nCbH-1. weightIdx=((x≪1)+1)*Dis[displacementX]+((y≪1)+1))*Dis[displacementY]-rho, and weightIdxAbs=Clip3(0,26,(abs(weightIdx)+4)≫3)

[0124] If x=0 and y=nCbH-1, the variable partIdx may be set to weightIdx>0.

[0125] The value of sampleWeightL[x][y] with x=0..nCbW-1 and y=0..nCbH-1 may be set according to Table 3, represented as GeoFilter: sampleWeightL[x][y]=weightIdx≦0?GeoFilter[weightIdxAbs]:8-GeoFilter[weightIdxAbs].

[0126] The value sampleWeightC[x][y] with x=0..nCbW-1 and y=0..nCbH-1 may be set as follows: sampleWeightC[x][y]=sampleWeightL[(x≪(SubWidthC-1))][(y≪(SubHeightC-1))]].

[0127] [Table 1]

[0128] [Table 2]

[0129] [Table 3]

[0130] IV.2 Minimum Mixed Weight Mask Storage To reduce the storage requirements of the pre-computed mixture masks, the minimal mixture mask storage method can achieve an 84-91% memory requirement reduction for mixture weight storage.

[0131] g_sampleWeight L Let [ ] denote the predefined masks for blending weights. N denotes the number of predefined masks in each set, and assuming N is set to NA≫1, NA is the number of angles supported in GEO. M×M denotes the size of the predefined masks for blending weights, and M is set to 128+((ND-1)×(128≫S))≪1, ND is the number of steps supported in GEO, and S is set to ND-1. For 32 angles with a 5-step setting, N is set to 16, and M is set to 192. For 24 angles with a 4-step setting, N is set to 12, and M is set to 224.

[0132] For a block of size W×H with geometric partition index K, the blending weights for the luma samples are derived as follows: The variables angle φ and distance ρ are obtained from a lookup table using the geometric partition index K. The variables offsetX and offsetY can be calculated as follows:

[0133]

number

[0134] An exemplary weighted sample prediction process with minimum blend weight mask storage for GEO is described below. Inputs to the weighted sample prediction process include two variables nCbW and nCbH that specify the width and height of the current coding block, two (nCbW) x (nCbH) arrays predSamplesLA and predSamplesLB, a variable angleIdx that specifies the angle index of the geometric partition, a variable distanceIdx that specifies the distance idx of the geometric partition, and a variable cIdx that specifies the color component index. Outputs of this process include a (nCbW) x (nCbH) array pbSamples of predicted sample values, and a variable partIdx.

[0135] The variable bitDepth may be derived as follows: if cIdx=0, then bitDepth=BitDepthY, and if cIdx=0, then bitDepth=BitDepthC.

[0136] The variables shift1=Max(5, 17-bitDepth), and offset1=1<<(shift1-1).

[0137] The weighting array for luma, sampleWeightL[x][y], and the weighting array for chroma, sampleWeightC[x][y], with x=0..nCbW-1 and y=0..nCbH-1, may be derived as follows:

[0138] Variable hwRatio=nCbH / nCbW.

[0139] The variables displacementX=angleIdx, and displacementY=(displacementX+8)%32.

[0140] Variable partIdx = (angleIdx ≥ 13 && angleIdx ≤ 27)?1:0.

[0141] The variable rho may be set to the following value using lookup table 2: rho=(Dis[displacementX]≪8)+(Dis[displacementY]≪8)

[0142] The variable shiftHor=0 if one of the following conditions is true: (1) angleIdx%16=8, and (2) angleIdx%16 !=0 and hwRatio≧1. If these conditions are not true, then shiftHor=1.

[0143] If shiftHor=0, offsetX=(256-nCbW)≫1, offsetY=(256-nCbH)≫1+angleIdx<16?(distanceIdx*nCbH)≫3:-((distanceIdx*nCbH)≫3).

[0144] Otherwise, if shiftHor=1, offsetX=(256-nCbW)≫1+angleIdx<16?(distanceIdx*nCbW)≫3:-((distanceIdx*nCbW)≫3), offsetY=(256-nCbH)≫1.

[0145] The variables weightIdx and weightIdxAbs can be calculated using lookup table 2 with x=0..nCbW-1 and y=0..nCbH-1 as follows: weightIdx=(((x+offsetX)≪1)+1)*Dis[displacementX]+(((y+offsetY)≪1)+1))*Dis[displacementY]-rho, weightIdxAbs=Clip3(0,26,abs(weightIdx))

[0146] The values ​​of sampleWeightL[x][y] with x=0..nCbW-1 and y=0..nCbH-1 may be set according to Table 3, represented as GeoFilter. sampleWeightL[x][y]=weightIdx≦0?GeoFilter[weightIdxAbs]:8-GeoFilter[weightIdxAbs]

[0147] The value sampleWeightC[x][y] with x=0..nCbW-1 and y=0..nCbH-1 may be set as follows: sampleWeightC[x][y]=sampleWeightL[(x<<(SubWidthC-1))][(y<<(SubHeightC-1))]]

[0148] Motion vector storage processing for V.GEO V.1 TPM-like motion vector derivation In some cases, the luma sample weights of the four corners of a 4x4 motion storage unit may be summed. The sum may be compared to two thresholds to determine whether two uni-predictive motion information and one of bi-predictive motion information are stored. The bi-predictive motion information may be derived using the same process as the TPM.

[0149] An exemplary motion vector storage process for GEO is described below.

[0150] The array motionIdx[xSbIdx][ySbIdx] with xSbIdx=0..(nCbW≫2)-1 and ySbIdx=0..(nCbH≫2)-1 may be derived as follows:

[0151] Variable threshScaler=(wIdx+hIdx)≫1)-1,threshLower=32≫threshScaler,threshUpper=32-threshLow er,Cnt=sampleWeightL[(xSbIdx≪2)][(ySbIdx≪2)]+sampleWeightL[(xSbIdx≪2)+3][(ySbIdx≪2)]+ sampleWeightL[(xSbIdx≪2)][(ySbIdx≪2)+3]+sampleWeightL[(xSbIdx≪2)+3][(ySbIdx≪2)+3],Cn t=partIdx?32-Cnt:Cnt,motionIdx[xSbIdx][ySbIdx]=Cnt≦threshLower?0:Cnt≧threshUpper?1:2.

[0152] When merge_geo_flag[xCb][yCb]=1, sType=motionIdx[xSbIdx][ySbIdx], xSbIdx=0..numSbX-1, ySbIdx=0..numSbY-1.

[0153] V.2 Simplified motion vector storage process In some cases, the motion vector storage process can be further simplified. The distance between the center position of the 4x4 motion storage unit and the division boundary can be calculated and compared with a fixed threshold to determine whether uni-predictive motion information or bi-predictive motion information is stored for the 4x4 motion storage unit. The sign of the distance indicates which uni-predictive motion information is stored in the uni-predictive storage case. The dependency between the blending mask and the motion storage can be removed.

[0154] If merge_geo_flag[xCb][yCb]=1, wIdx=log2(cbWidth),hIdx=log2(cbHeight),whRa tio=(wIdx≧hIdx)?wIdx-hIdx:hIdx-wIdx,scaleIdx=(wIdx≧hIdx)?hIdx-3:wIdx-3,disp lacementX=angleIdx,displacementY=(displacementX+8)%32,angleN=(wIdx≧hIdx)?(angleIdx≫3&1)?angleIdx%8:8-angleIdx%8:(angleIdx≫3&1)?8-angleIdx%8:angleIdx%8.

[0155] The variable rho is set to the following values ​​using the lookup tables designated as stepDis and Dis as specified in Tables 1 and 2: rho=distanceIdx*(stepDis[whRatio][angleN]≪scaleIdx)+(Dis[displacementX]≪wIdx)+(Dis[displacementY]≪hIdx)

[0156] The variable motionOffset is set to the following value using the lookup table designated as Dis specified in Tables 1 and 2: motionOffset=3*Dis[displacementX]+3*Dis[displacementY]

[0157] The variable motionIdx is calculated using lookup table 2 as follows: motionIdx=((xSbIdx<<3)+1)*Dis[displacementX]+((xSbIdx<<3)+1))*Dis[displacementY]-rho+motionOffset.

[0158] The variable sType is derived as follows: if partIdx=1, then sType=abs(motionIdx)<256?2:motionIdx≦0?1:0; if partIdx=1 is not, then sType=abs(motionIdx)<256?2:motionIdx≦0?0:1.

[0159] V.3 Minimum motion vector storage process To reduce the memory required to store the mask for motion field storage, a process may derive all information from a predefined mask for the mask of motion field storage. This process is invoked when decoding a coding unit with MergeWedgeFlag[xCb][yCb]=1. Inputs to this process include a luma position (xCb, yCb) that specifies the top-left sample of the current coding block relative to the top-left luma sample of the current picture, a variable cbWidth that specifies the width of the current coding block of luma samples, a variable cbHeight that specifies the height of the current coding block of luma samples, luma motion vectors of 1 / 16 fractional sample precision mvA and mvB, reference indices refIdxA and refIdxB, and prediction list flags predListFlagA and predListFlagB.

[0160] The variables numSbX and numSbY, which specify the number of 4x4 blocks in the current coding block in the horizontal and vertical directions, are set equal to numSbX=cbWidth>>2 and numSbY=cbHeight>>2.

[0161] Variable displacementX=angleIdx, displacementY=(displacementX+8)%32, hwRatio=nCbH / nCbW.

[0162] The variable shiftHor=0 if one of the following conditions is true: (1) angleIdx%16=8, and (2) angleIdx%16 !=0 and hwRatio≧1. If these conditions are not true, then shiftHor=1.

[0163] Variable partIdx = (angleIdx ≥ 13 && angleIdx ≤ 27)?1:0.

[0164] If shiftHor=0, offsetX=(64-numSbX)≫1, offsetY=(64-numSbY)≫1+angleIdx<16?(distanceIdx*nCbH)≫5:-((distanceIdx*nCbH)≫5). If shiftHor is not 0 and shiftHor=1, offsetX=(64-numSbX)≫1+angleIdx<16?(distanceIdx*nCbW)≫5:-((distanceIdx*nCbW)≫5), offsetY=(64-numSbY)≫1.

[0165] The value of the variable rho is derived according to the following formula and is derived according to the Dis lookup table specified in Table 2: rho=(Dis[displacementX]≪8)+(Dis[displacementY]≪8).

[0166] The variable motionOffset is set equal to the following value using the lookup table designated as Dis specified in Tables 1 and 2: motionOffset=3*Dis[displacementX]+3*Dis[displacementY]

[0167] For each 4x4 sub-block at sub-block index (xSbIdx, ySbIdx) with xSbIdx=0..numSbX-1 and ySbIdx=0..numSbY-1, the variable motionIdx is calculated using lookup table 2 as follows: motionIdx=(((xSbIdx+offsetX)≪3)+1)*Dis[displacementX]+(((xSbIdx+offsetY≪3)+1))*Dis[displacementY]-rho+motionOffset

[0168] VI. Blending Processing and Motion Field Storage In GEO, as described in Sections III, IV, and V, the weighted sample prediction process and motion field storage decision are computationally expensive. In some examples (e.g., as described in Sections IV.1 and V.1), when mixed weighted and stored motion vector types are calculated on the fly, the number of multiplications, shifts, and additions for a block of samples of size W×H may be as follows: Multiplication: 3 + 2 × W × H + 0 × (W × H / 16) Shift: 6 + 3 × W × H + 8 × (W × H / 16) Addition: 10 + 6 × W × H + 7 × (W × H / 16) For example, for an 8x8 block, 2.04 multiplications, 3.09 shifts, and 6.16 additions are required per sample. Furthermore, in some examples, three lookup tables are used for on-the-fly calculations. ρ in Equation 4 is a complex function involving floating-point arithmetic and is implemented using a lookup table. The other two lookup tables include a cos[.] value lookup table and a conversion table for converting the blending weight index to a blending weight value. Therefore, on-the-fly calculation of the blending weight mask and motion vector type mask for each GEO-coded block is computationally demanding.

[0169] To reduce computational complexity, in some examples, the mixed weight mask and motion vector storage type mask may be calculated and stored in memory in advance. However, the large memory storage size is a design challenge. Taking the 140-mode variant of GEO as an example, the memory required to store this information can be calculated as follows: -For mixed weights: (8x8 + 8x16 + 8x32 + 8x64 + 16x8 + 16x16 + 16x32 + 16x64 + 32x8 + 32x16 + 32x32 + 32x64 + 64x8 + 64x16 + 64x32 + 64x64 + 64x128 + 128x64 + 128x128) x 140 x 4 = 26,414,080 bits = 3,301,760 bytes ≒ 3.3 MB -For motion field storage: (2 x 2 + 2 x 4 + 2 x 8 + 2 x 16 + 4 x 2 + 4 x 4 + 4 x 8 + 4 x 16 + 8 x 2 + 8 x 4 + 8 x 8 + 8 x 16 + 16 x 2 + 16 x 4 + 16 x 8 + 16 x 16 + 16 x 32 + 32 x 16 + 32 x 32) x 140 x 2 = 825,440 bits = 103,180 bytes ≒ 103 kbytes

[0170] Based on the above calculations, the memory storage requirements for the three variants of GEO are listed in Table 4.

[0171] [Table 4]

[0172] Due to the large number of partition modes, it may be difficult in a practical implementation to store all adaptive weights and motion vector type masks for motion field storage for each block size and partition mode. To reduce the memory required to store adaptive weights and motion vector type masks for motion field storage, two sets of predefined masks, one for blending weight derivation and the other for masks for motion field storage, may be used using the techniques described in Sections IV.2 and V.3. The memory required for blending weights and masks for motion field storage can be reduced. However, in a practical implementation, the amount of memory required is still large. If N is N A ≫1, and N A is the number of angles supported in GEO, and M is 128+((N D -1)×(128≫S))≪1, and N D is the number of steps supported in GEO mode, and S is ND Assume it is set to -1. The number of bits required to store the predefined masks is listed below. -For mixed weighting: (M×M)×N×4 -For motion field storage: (M x M) / 16 x N x 2

[0173] The memory storage requirements for the three variants of GEO are listed in Table 5 below.

[0174] [Table 5]

[0175] Embodiments are described below to further simplify the weighted blending and motion field storage processes in GEO. These techniques allow for the use of small lookup tables of trigonometric values ​​(e.g., cosine values) to calculate weighting factors on the fly and to determine the motion vector storage type.

[0176] As previously mentioned, the blending weight mask for the geometric merge mode may be derived from the sample positions and split boundary distances using a lookup table with Equations 7 and 9 reproduced below.

[0177]

number

[0178] In Equation 3, φ represents the angle value corresponding to the partition edge, and ρ is the distance between the center of the current coding block and the partition boundary. In Equation 5, n represents the total number of distance quantization steps, and i represents the distance step index for the GEO partition with angle φ. The shifted backward ρ in Equation 5 margin The value is to avoid the partition boundary being too close to the corner of the current coding block. As an example, ρ for an 8x8 block is margin A typical value for may be 1.0 in some instances.

[0179] Block and angle dependent ρ margin In one embodiment, the value ρ of Equation 5 margin is used to avoid the partition boundary (partition edge) being too close to the corner of the coding block, and is not constant. For example, the value ρ margin may vary depending on the block width, and / or height, and / or φ (angle of the dividing boundary).

[0180] Value ρ margin may be defined to be a function of the GEO partition angle φ and the width and height of the current coding block. For example, ρ margin may be derived from the following formula:

[0181]

number

[0182] According to Equations 17 and 18, the distance offset ρ can be simplified as follows:

[0183]

number

[0184] Therefore, the calculation of the distance offset ρ can be accomplished by shift, multiplication, and addition operations in addition to a cosine value lookup table operation. margin It is simplified compared to using the value.

[0185] Blending weighted index calculations on the fly using a single lookup table In one embodiment, only a lookup table for the cosine calculation is used during the blend weight index calculation, so that all weight index calculations may be performed on the fly without checking a large table to store the blend weight mask.

[0186] Based on the above Equation 18, the GEO blending mask derived from the distance from the sample position to the split boundary as shown in Equation 3 may be further simplified as follows:

[0187]

number

[0188] If the distance step number n is a power of 2, the division operation in Equation 21 can be implemented using a right shift operation as shown in Equation 22, with or without rounding the offset before the right shift.

[0189]

number

[0190] According to Equation 22, the mixed weight index for each sample can be obtained by using a multiplier, an addend, and one cos[.] lookup table. Also, Equation 20 indicates that only one cos[.] table is used for the mixed weight index of all samples in the current CU. This also implies that this cos[.] value may be accessed once and then propagated to all samples in the current CU for weight index calculation.

[0191] Integer-only calculations In one embodiment, to avoid floating-point operations, the components for deriving the mixed weighted index may be scaled up, resulting in a scaled-up value of the weighted index, which may later be scaled back to its normal value range.

[0192] For example, each cosine value in the cos[.] lookup table may be implemented as an m-bit fixed-point value, where m may be a positive value such as 6 or 3. Furthermore, the sample center point is also adopted for digital images with discrete sampling for the mixed weight index calculation. The weight index wIdx(x,y) is calculated by multiplying the weight index by 2 to avoid floating-point operations and compensate for the discrete sampling situation. m+4 Therefore, Equation 22 can be rewritten as Equation 23. A rounding offset may be applied to maintain relatively high precision.

[0193]

number

[0194] If the distance step number n is a power of 2, the division operation in Equation 23 can be implemented using a right shift operation, as shown in Equation 24. A rounding offset may also be applied.

[0195]

number

[0196] Angles in the four quadrants In one embodiment, different formulas may be used to perform the weighted index calculation depending on the quadrant of the split boundary angle φ. For example, for split boundary calculation, cos(φ) and

[0197]

number

[0198] Both values ​​of , , and , may be positive. Therefore, four different blending weight mask formulas may be used for the segment angle indexes corresponding to the four different quadrants. The blending weight index formulas for the four different quadrants are shown below.

[0199]

number

[0200] Mixed weighted index calculation based on row-wise and column-wise In one embodiment, the weighted index wIdx(x,y) may be calculated row by row, i.e., the value of the current row wIdx(x,y) is derived based on the value of the previous row wIdx(x,y-1). Alternatively, the weighted index wIdx(x,y) may be calculated column by column, i.e., the weighted index of the current column wIdx(x,y) is derived based on the weighted index of the previous column wIdx(x-1,y).

[0201] For sample position (x,y), Equations 26-28 may be used to derive the blending mask based on Equation 23.

[0202]

number

[0203] As shown in Equation 26, the weighted index wIdx(x,y) may be derived from the mixed weighted index of the adjacent left pixel in the previous column with a fixed offset value. The fixed offset value is cos(φ), which is a simple lookup table value with a corresponding angle index and a scaling factor. Therefore, only one column of mixed weighted index values ​​is required for mask storage. The other columns of weighted indexes may be determined by using the mixed weighted index values ​​of the previous column with a fixed offset value.

[0204] For a sample location (x,y), the blending mask or blending weight index for this pixel sample is derived using Equations 29-31 based on Equation 23.

[0205]

number

[0206] In Equation 29, the weighted index wIdx(x,y) may be derived from the blended weighted index of the upper adjacent pixel in the upper row with a fixed offset value.

[0207]

number

[0208] looks up the given angle index from a simple lookup table cos[.]

[0209]

number

[0210] The weights are derived by using the phase shift together. Therefore, only one row of blending weights is needed for mask storage. Other rows may be implemented by using the blending weights of the previous row with a fixed offset value.

[0211] Independent derivation of weighted indexes In one embodiment, the weighted index at position (x, y) of the coding block may be derived from a particular weighted index value wIdx(0, 0) (which may be determined based on the block size, distance offset ρ, and partition angle φ) depending on the coordinates (x, y) and the cosine table. In this way, the weighted index for each sample of the coding block may be derived independently.

[0212] In equation 7, the following equation may be derived:

[0213]

number

[0214] Therefore, after determining the value of wIdx(0,0), the weighted index of each sample in the block may be calculated in parallel with Equation 32.

[0215] Conversion of weighted indexes to blended weights without using lookup tables In one embodiment, the lookup table based weighting index for the final blending weighted transform is replaced with a computation based transform: since the lookup table checking operation is eliminated, the final weighting coefficients for each sample may be derived in parallel.

[0216] In some examples, such as the GEO weighted sample processing described in Section VI, the values ​​of the sample weights are set according to a lookup table (e.g., the GeoFilter[ ] lookup table, Table 3). To remove the constraints associated with lookup tables and enable parallel weight derivation, the sample weight values ​​may be derived on the fly based on a linear function of the weight index. The linear function can convert the weight index to a blend weight without the aid of a lookup table.

[0217] As an example, the following equation (Equation 34) may be used to convert the weight index to a blend weight: weight(x,y)=(2 idx2wShiftBit+2 -wIdx(x,y))≫idx2wShiftBit (Formula 34)

[0218] For calculations based on floating-point arithmetic (e.g., Equation 19 and Equation 20), no scale-up may be used to calculate wIdx(x,y), and idx2wShiftBit in Equation 32 may be set to '0'. The sample weights may be derived as follows: weight(x,y)=4-wIdx(x,y) (Equation 35)

[0219] In the case of calculations based on fixed-point arithmetic (eg, Equation 19 and Equation 20), idx2wShiftBit in Equation 30 may be explained as in Equation 36. idx2wShiftBit=m+3 (Formula 36)

[0220] The sample weights may be derived on the fly by using a right shift operation as shown in Equation 37. weight(x,y)=(2 m+5 -wIdx(x,y))≫(m+3) (Equation 37)

[0221] A typical value for m may be the number of bits of precision in the cosine table, for example m may be typically 6 or 3.

[0222] Motion index calculation without lookup tables In one embodiment, a calculation method without a lookup table can be used to determine the motion index. For example, the motion index of the motion storage unit of the current coding block can be calculated by, for example, the coordinates (x sb ,y sb ), and the segment distance offset ρ (denoted by n and i) of the current coding block, the segment angle φ of the current coding block, and the block size of the current coding block. As a result, the motion index motionIdx(x sb ,y sb ) may be derived independently (in parallel) at the same time.

[0223] In some examples, a motion vector storage process may be derived on the fly using the distance between the center position of a motion storage unit (subblock) and a partition boundary, without using a motion storage process such as a TPM. The motion storage unit may have a size of 4x4 samples or other subblock sizes (e.g., 8x8 samples). The center position of a WxH subblock may be defined as an integer position at (W / 2, H / 2) or (W / 2-1, H / 2-1), or an adjacent position to these integer positions. Alternatively, a subpel position ((W-1) / 2.0, (H-1) / 2.0) may be defined as the center position. The distance value is compared with a fixed threshold to determine whether uni-predictive or bi-predictive motion information is stored in the motion storage unit. The sign of the distance indicates uni-predictive motion information that can be stored in the uni-predictive storage case. Therefore, the dependency between the blending mask and the motion storage can be removed.

[0224] In one example, the motion storage unit (sub-block) has a size of 4x4 samples. sb and y sb The variable x specifies the position of the 4x4 sub-block of the current wxh coding block in the horizontal and vertical directions. sb and y sb is the formula, 0≦x sb <(w≫2) and the formula, 0≦y sb <(h≫2). Using the concept of Equation 21 and the detailed derivation for discrete sampling with scaling in Equation 19, we may derive the distance between the center position of the 4x4 motion storage unit and the partition boundary in Equation 38.

[0225]

number

[0226] If the distance step number n is a power of two values, then a right shift operation may be used to implement the division operation in Equation 38, as shown in Equation 39. A rounding offset may also be applied to maintain relatively high precision.

[0227]

number

[0228] Motion index derived from mixed weighted index In one embodiment, the motion storage units (sub-blocks) of the coding block are represented by motionIdx(x sb ,y sb The motion index, denoted by ), is directly derived from the mixed weighted index of the sample position within the sub-block. In this way, the computational cost for determining the motion index can be saved or reduced.

[0229] As described in Section V, the motion index may be derived based on the distance between the center position of the motion storage unit and the partition boundary. The blending weighted index may be derived from the distance between the sample and the partition boundary. Therefore, the motion index may be estimated from the blending weighted index of the sample within the corresponding sub-block and may not be located at the center of the sub-block.

[0230] In one example, the estimation is performed according to Equation 40.

[0231]

number

[0232] In Equation 36, the motion storage unit of the motion field of the coding block is assumed to have a size of 4x4 samples. The coordinates of a sample position within the motion storage unit are represented by (i,j). For example, for a motion storage unit with coordinates of (1,0) in the motion field, and for a sample position with coordinates of (2,2) in the motion storage unit specified for calculating a motion index, the weighted index at the sample position ((1<<2)+2, (0<<2)+2) of the coding block, i.e., (6,2), may be used as the motion index of the motion storage unit. The calculation process can be shown as follows: motionldx(1,0)=wIdx((1≪2)+2,(0≪2)+2)=wIdx(6,2)(Formula 41)

[0233] In various examples, (i,j) may be equal to (1,1), (1,2), (2,1), and (2,2), which correspond to sample positions adjacent to the center position (1.5,1.5) of the corresponding sub-block.

[0234] More generally, 2 n x2 n For a motion storage unit with the size of a sample, the estimation may be realized according to Equation 42:

[0235]

number

[0236] In Equations 40-42, the blending weighted index value at sample position (x, y) of the coding block, represented by wIdx(x, y), can be obtained in various ways in various examples. After the blending weighted index value is calculated during the weighted blending process, the blending weighted index at a specified position in each motion vector storage unit may be directly used as a motion index value for determining the motion vector type to be stored for each motion storage unit. This can reduce computational complexity compared to calculating the motion index based on the distance from the center sample position in the motion storage unit to the partition edge.

[0237] VII. EXEMPLARY PROCESSING OF GEOMETRIC PARTITIONING MODES 12 shows a flowchart outlining a process (1200) according to some embodiments of the present disclosure. In various embodiments, the process (1200) is performed by processing circuitry, such as the processing circuitry of the terminal devices (210), (220), (230), and (240), the processing circuitry performing the functions of the video decoder (310), and the processing circuitry performing the functions of the video decoder (410). In some embodiments, the process (1200) is implemented by software instructions, and thus, the processing circuitry performs the process (1200) when it executes the software instructions. The process (1200) begins at (S1201) and proceeds to (S1210).

[0238] At (S1210), syntax elements may be received from the bitstream of the coded video. The syntax elements may be associated with a current coding block that is partitioned into a first portion and a second portion along a partition edge for prediction in a geometric partitioning mode (GPM). For example, the following syntax elements may be signaled in the bitstream: a CU-level GPM enable flag indicating that GPM is enabled for the current coding block, a GPM index indicating the partitioning mode (corresponding to the partition angle index and distance offset index in the table) that applies to the current coding block, and two GPM merge indices corresponding to the first and second portions of the current coding block.

[0239] At (S1220), a weighted index at a sample position of the current coding block may be determined. The weighted index may correspond to, for example, the distance of the sample position to a partition edge. The weighted index may then be used to derive blending weights for blending two prediction signals corresponding to the first and second portions of the current coding block. In one example, the weighted index may be converted to a blending weight using a linear function of the weighted index.

[0240] At (S1230), a stored motion vector type for a first motion storage unit of a motion field of a current coding block may be determined based on the motion index of the first motion storage unit. The weighted index at the sample position of the current coding block determined at (S1220) is used as the motion index of the first motion storage unit. For example, the weighted index determined at (S1220) can be used to estimate the motion index at the center position of the first motion storage unit to determine the stored motion vector type. In this way, the computational cost for calculating the motion index at the center position of the first motion storage unit can be saved or reduced. The decoding performance by GPM can be improved.

[0241] At (S1240), the motion field of the current coding block may be stored based on the stored motion vector type determined for the first motion storage unit of the motion field of the current coding block. For example, two motion vectors corresponding to two GPM merge indexes may be represented as MV1 and MV2. Depending on the stored motion vector type, MV1 from the first portion of the geometric partition, MV2 from the second portion of the geometric partition, and the combined MV of MV1 and MV2 are stored in the motion field for the first motion storage unit. Process (1200) may proceed to (S1299) and end at (S1299).

[0242] VIII. Computer Systems The techniques described above may be implemented using computer-readable instructions and as computer software physically stored on one or more computer-readable media. For example, Figure 13 illustrates a computer system (1300) suitable for implementing certain embodiments of the disclosed subject matter.

[0243] Computer software may be encoded using any suitable machine code or computer language, which may be subjected to mechanisms such as assembly, compilation, linking, etc. to create code containing instructions that may be executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or may be executed via interpretation, microcode execution, etc.

[0244] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, Internet of Things devices, and the like.

[0245] 13 for computer system 1300 are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing embodiments of the present disclosure. Neither should the arrangement of components be interpreted as having any dependency or requirement regarding any one or combination of components illustrated in the exemplary embodiment of computer system 1300.

[0246] The computer system (1300) may include certain human interface input devices. Such human interface input devices may respond to input by one or more human users, for example, via tactile input (e.g., keystrokes, swipes, data glove movements), audio input (e.g., voice, clapping), visual input (e.g., gestures), or olfactory input (not shown). The human interface devices may also be used to capture certain media not necessarily directly associated with conscious human input, such as audio (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images captured from a still image camera), and video (2D video, 3D video including stereoscopic video, etc.).

[0247] The input human interface devices may include one or more (only one of each is shown) of a keyboard (1301), a mouse (1302), a trackpad (1303), a touchscreen (1310), a data glove (not shown), a joystick (1305), a microphone (1306), a scanner (1307), and a camera (1308).

[0248] The computer system (1300) may also include certain human interface output devices that may stimulate one or more of the human user's senses, for example, through tactile output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via a touchscreen (1310), data gloves (not shown), or joystick (1305), although haptic feedback devices that do not function as input devices may also be present), audio output devices (e.g., speakers (1309), headphones (not shown)), visual output devices (e.g., screens (1310) including CRT screens, LCD screens, plasma screens, and OLED screens, each with or without touchscreen input capability, each with or without haptic feedback capability, some of which may be capable of outputting two-dimensional visual output or three-dimensional or higher-dimensional output via means such as stereo projection output, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown). These visual output devices (e.g., the screen (1310)) may be connected to the system bus (1348) via a graphics adapter (1350).

[0249] The computer system (1300) may also include human-accessible storage devices and their associated media, such as optical media (1321) including CD / DVD or similar media as well as CD / DVD ROM / RW (1320), USB memory (1322), external hard drives or external solid state drives (1323), legacy magnetic media such as tape and floppy disks (not shown), dedicated ROM / ASIC / PLD-based devices such as security dongles (not shown), etc.

[0250] Those skilled in the art will also understand that the term "computer-readable medium" as used in connection with the subject matter of this disclosure does not encompass transmission media, carrier waves, or other transitory signals.

[0251] The computer system (1300) may also include a network interface (1354) to one or more communication networks (1355). The one or more communication networks (1355) may be, for example, wireless, wired, or optical. Furthermore, the one or more communication networks (1355) may be local, wide area, metropolitan, vehicular and industrial, real-time, delay-tolerant, etc. Examples of the one or more communication networks (1355) include local area networks such as Ethernet and wireless LAN, mobile communication networks including GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable TV, satellite TV, and terrestrial broadcast TV, vehicle and industrial networks including CAN bus, etc. Certain networks typically require an external network interface adapter attached to a particular general-purpose data port or peripheral bus (1349) (e.g., a USB port on the computer system (1300)), while other networks are typically integrated into the core of the computer system (1300) by attachment to a system bus (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system) as described below. Using any of these networks, the computer system (1300) may communicate with other elements. Such communications may be unidirectional receive only (e.g., broadcast TV), unidirectional transmit only (e.g., a CAN bus to a particular CAN bus device), or bidirectional, for example, to other computer systems using local or wide-area digital networks. Specific protocols and protocol stacks may be used with each of these networks and network interfaces, as described above.

[0252] The aforementioned human interface devices, human-accessible storage devices, and network interfaces may be attached to the core (1340) of the computer system (1300).

[0253] The core (1340) may include one or more central processing units (CPUs) (1341), one or more graphics processing units (GPUs) (1342), one or more dedicated programmable processing units in the form of field programmable gate arrays (FPGAs) (1343), one or more task-specific hardware accelerators (1344), etc. These devices may be connected via a system bus (1348), along with read-only memory (ROM) (1345), random access memory (1346), and internal mass storage (1347) such as an internal, non-user-accessible hard drive or SSD. In some computer systems, the system bus (1348) may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, etc. Peripheral devices may be attached directly to the core's system bus (1348) or via a peripheral bus (1349). Architectures for peripheral buses include PCI, USB, etc.

[0254] The CPU (1341), GPU (1342), FPGA (1343), and accelerator (1344) may execute specific instructions that, in combination, may constitute the aforementioned computer code. That computer code may be stored in ROM (1345) or RAM (1346). Transient data may also be stored in RAM (1346), while persistent data may be stored, for example, in internal mass storage (1347). Rapid storage and retrieval from any of the memory devices may be enabled through the use of cache memory, which may be closely associated with one or more CPUs (1341), one or more GPUs (1342), one or more mass storage (1347), one or more ROMs (1345), one or more RAMs (1346), etc.

[0255] The computer-readable medium may bear computer code for performing various computer-implemented operations. The medium and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those skilled in the computer software arts.

[0256] By way of example and not limitation, the computer system (1300) having an architecture, and in particular its cores (1340), may provide functionality as a result of processors (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media may be media associated with user-accessible mass storage, as described above, as well as media associated with specific storage of the cores (1340) that is non-transitory in nature, such as the core's internal mass storage (1347) or ROM (1345). Software implementing various embodiments of the present disclosure may be stored on such devices and executed by the cores (1340). The computer-readable media may include one or more memory devices or one or more chips, depending on particular needs. The software may cause the cores (1340), and in particular the processors (including CPUs, GPUs, FPGAs, etc.) therein, to perform particular processes or particular portions of particular processes, as described herein, including defining data structures stored in RAM (1346) and modifying such data structures in response to software-defined operations. Additionally, or alternatively, a computer system may provide functionality as a result of logic embodied in hardwired or otherwise circuitry (e.g., accelerator (1344)), which may operate in place of or in conjunction with software to perform particular operations or portions of particular operations described herein. References to software may encompass logic, and vice versa, where appropriate. References to computer-readable media may encompass, where appropriate, circuitry (such as an integrated circuit (IC)) that stores software for execution, circuitry that implements logic for execution, or both. The present disclosure encompasses any appropriate combination of hardware and software.

[0257] While this disclosure has described several exemplary embodiments, there are alterations, substitutions, and various substitute equivalents that fall within the scope of this disclosure. It will thus be appreciated that those skilled in the art will be able to devise numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within the spirit and scope of the present disclosure.

[0258] Appendix A: Acronyms ASIC: Application Specific Integrated Circuit BMS: Benchmark suite CANBus: Controller Area Network Bus CD: Compact Disc CPU: Central Processing Unit CRT: cathode ray tube CTB: coding tree block CTU: Coding Tree Unit CU: Coding Unit DVD: Digital video disc FPGA: Field Programmable Gate Area GEO: Geometric merge mode GOP: Group of Pictures GPU: Graphics Processing Unit GSM: Global System for Mobile Communications HDR: High Dynamic Range HEVC: High Efficiency Video Coding HRD: Hypothetical Reference Decoder IC: Integrated Circuit JEM: Joint Exploration Model JVET:Joint Video Exploration Team LAN: Local Area Network LCD: Liquid crystal display LTE: Long Term Evolution MV: Motion Vector OLED: Organic Light Emitting Diode PB: Predicted Block PCI: Peripheral Component Interconnect PLD: Programmable Logic Device PU: Prediction Unit RAM: Random Access Memory ROM: Read-Only Memory SDR: Standard Dynamic Range SEI: Additional Enhancement Information SNR: Signal to Noise Ratio SSD: Solid State Drive TPM: Triangulation Mode TU: Conversion unit USB: Universal Serial Bus VUI: Visual Usability Information VVC: Versatile Video Coding [Explanation of symbols]

[0259] 200 Communication Systems 210 Terminal Equipment 220 Terminal Equipment 230 Terminal Equipment 240 Terminal Equipment 250 Communication Network 301 Video Source 302 Stream 303 Video Encoder 304 Video Bitstream 305 Streaming Server 306 Client Subsystem 307 Video Data 308 Client Subsystem 309 Video Data 310 Video Decoder 311 Video Picture 312 Display 313 Capture Subsystem 320 Electronic equipment 330 Electronic equipment 401 Channel 410 Video Decoder 412 Rendering Device 415 Buffer Memory 420 Parser 421 Symbol 430 Electronic equipment 431 Receiver 451 Scaler / Descaler Unit 452 Intra-picture prediction unit 453 Motion Compensation Prediction Unit 455 Concentrator 456 Loop Filter Unit 457 Reference Picture Memory 458 Current Picture Buffer 501 Video Source 503 Video Encoder 520 Electronic equipment 530 Source Encoder 532 encoding engine 533 Local Video Decoder 534 Reference Picture Memory 535 Predictor 540 Transmitter 543 Video Sequences 545 Entropy Encoder 550 Controller 560 Communication Channel 603 Video Encoder 621 Overall Controller 622 Intra Encoder 623 Residual Calculator 624 Residual Encoder 625 Entropy Encoder 626 Switch 628 Residual Decoder 630 Interencoder 710 Video Decoder 771 Entropy Decoder 772 Intra Decoder 773 Residual Decoder 774 Reconstruction Module 780 Interdecoder 1200 Processing 1300 Computer Systems 1301 Keyboard 1302 Mouse 1303 Trackpad 1305 Joystick 1306 Microphone 1307 Scanner 1308 Camera 1309 Speaker 1310 Visual Output Device Screen 1321 Optical media 1322 USB memory 1323 External Solid State Drive 1340 cores 1343 Field Programmable Gate Area 1344 Hardware Accelerator 1345 Read-Only Memory ROM 1346 Random Access Memory 1347 cores internal large capacity storage 1348 system bus 1349 Peripheral Bus 1350 graphics adapter 1354 Network Interface 1355 Communication Network

Claims

[Claim 1] 1. A method of video decoding at a video decoder, comprising: receiving syntax elements from a bitstream of coded video associated with a current coding block partitioned into a first portion and a second portion along a partition edge for prediction in a geometric partition mode; determining weighting indices at sample positions of the current coding block, the weighting indices being used to derive mixing weights for mixing two prediction signals corresponding to the first and second portions of the current coding block; determining a stored motion vector type for the first motion storage unit of the motion field of the current coding block based on a motion index of the first motion storage unit, wherein the weighted index at the sample position of the current coding block is used as the motion index of the first motion storage unit; storing the motion field of the current coding block based on the stored motion vector type determined for the first motion storage unit of the motion field of the current coding block.

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