Geometric partitioning mode in video coding

Abstract

To provide a geometric partitioning mode in video coding.SOLUTION: There is provided, a method of video decoding that includes a step for receiving a syntax element from a bitstream of a coded video associated with a current coding block that is partitioned into a first part and a second part along a partition edge for prediction in a geometric partitioning mode, and a step for determining a weight index at a sample position of the current coding block. A stored motion vector type for a first motion storage unit in a motion field of the current coding block is determined on the basis of, a motion index of the first motion storage unit. The weight 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 can be stored on the basis of, the stored motion vector type determined for the first motion storage unit in the motion field of the current coding block.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application 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 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 encoding. [Background technology]

[0003] The discussion of the background art provided herein is intended to provide general information relevant to the present disclosure. The inventors' work is not admitted, expressly or impliedly, as prior art to the present disclosure to the extent described in this Background section, as well as in aspects of the description 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 sequence of pictures, each having spatial dimensions of, for example, 1920x1080 luminance samples and associated chrominance samples. The sequence of pictures may have a fixed picture rate, for example, 60 pictures per second or 60 Hz, or a variable picture rate (also informally known as frame rate). Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 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 the input video signal through compression. Compression may help reduce the aforementioned bandwidth or storage space requirements, in some cases by more than one order of magnitude. Both lossless and lossy compression, as well as combinations thereof, may be used. Lossless compression refers to techniques where an exact copy of the original signal can be reconstructed from the compressed 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 signals is small enough to make the reconstructed signal useful for the intended application. For video, lossy compression is widely used. The amount of distortion that is tolerated depends on the application, for example, users of a particular consumer streaming application may tolerate higher distortion than users of a television distribution application. 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 a number of 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), the motion parameters include a motion vector, a reference picture index and a reference picture list usage index, as well as additional information used for inter predicted sample generation. The motion parameters can be signaled in an explicit or implicit manner. When a CU is coded using skip mode, it 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, by which the motion parameters of the current CU are obtained from neighboring CUs, which include spatial and temporal candidates and additional schedules introduced, for example, in VVC. The merge mode can be applied to any inter predicted CU, not just to skip mode. An alternative to the merge mode is to explicitly transmit the motion parameters. The motion vector, the corresponding reference picture index of each reference picture list, and the reference picture list usage flag and other necessary information are explicitly signaled to each CU.

[0008] Some inter-predictive coding tools include extended 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, an 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) average MVPs over pairs, and (5) zero MVs.

[0010] The size of the merge list is signaled in the slice header, and the maximum allowed size of the merge list is possibly, e.g., 6. For each CU code in the 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 with the context, and bypass coding is used for the other bins.

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

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

[0013] FIG. 1C illustrates motion vector scaling of a temporal merge candidate. In some cases, only one temporal merge candidate can be added to the merge candidate list. In particular, in the derivation of this temporal merge candidate, a scaled motion vector is derived based on the co-located CUs that belong to the collocated reference pictures. The reference picture list used for the derivation of 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 FIG. 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 an example location of a temporal merge candidate. A temporal merge candidate is selected between a CU at position C0 and a 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 apparatus 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 encoded 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, and to determine a weighted index at a sample position of the current coding block. The weighted index is used to derive a mixing weight 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 store a 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 a motion index of the first motion storage unit.

[0016] In one embodiment, the sample position of the current coding block where the weighted index is used as the motion index of the first motion storage unit is a sample position in the first motion storage unit of the motion field of the coding block. In one embodiment, the sample position of the current coding block where the weighted index is used as the motion index of the first motion storage unit is a sample position adjacent to a 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 4×4 samples, and the sample position of the current coding block where the weighted index is used as the motion index of the first motion storage unit is a sample position of coordinates (2,2) in 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 4×4 samples and stores (x 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), and ((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 the weighting indexes at the sample positions of the current coding block into mixing weights for mixing the two prediction signals. The conversion may be based on a linear function of the weighting indexes at the 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 a 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 weighting 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 weighting 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 weighting 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 a neighboring 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 the accompanying drawings. [Brief description of the drawings]

[0035] [Figure 1A] FIG. 13 illustrates exemplary locations of spatial merge candidates. [Figure 1B] FIG. 13 illustrates an example candidate pair considered for redundancy checking of spatial merge candidates. [Figure 1C] FIG. 13 illustrates an example of motion vector scaling for temporal merge candidates. [Figure 1D] FIG. 13 illustrates exemplary positions for temporal merge candidates. [Diagram 2] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system according to one embodiment. [Diagram 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. [Diagram 5] FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to one embodiment. [Figure 6] FIG. 4 is a block diagram of an encoder according to another embodiment. [Figure 7] FIG. 4 is a block diagram of a decoder according to another embodiment. [Figure 8A] FIG. 2 illustrates an example triangular section in accordance with some embodiments. [Figure 8B] FIG. 2 illustrates an example triangular section in accordance with some embodiments. [Figure 9] A diagram illustrating uni-predictive motion vector selection for triangular partitioning mode according to some embodiments. [Figure 10A] FIG. 2 illustrates an example weighting map for luma according to some embodiments. [Figure 10B] FIG. 2 illustrates an example weighting map for chroma according to some embodiments. [Figure 11] FIG. 1 illustrates an example geometric partitioning mode in accordance with 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 PREFERRED EMBODIMENTS

[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 a plurality of 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 according to 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 over the network (250) to the other of the terminal devices (230) and (240). 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), can decode the encoded video data to recover the video pictures, and can display the video pictures on an accessible display device in response to the recovered video data.

[0038] In the example of FIG. 2, the 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 may not be so limited. The embodiments of the present disclosure find application with laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. The network (250) represents any number of networks that convey encoded video data between the terminal devices (210), (220), (230), and (240), including, for example, wired communication (cable) networks and / or wireless communication networks. The communication network (250) may exchange data in circuit-switched and / or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of this description, the architecture of the network (250) and the topology of the network (250) may be irrelevant to the operation of the present disclosure, unless otherwise described herein below.

[0039] 3 illustrates an arrangement of video encoders and video decoders 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 taken by a digital camera. The stream of video pictures (302), illustrated as a thick line to emphasize the high amount of data 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)), illustrated as a thin line to emphasize the lower amount of data compared to the stream of video pictures (302), may be stored in a streaming server (305) for future use. One or more streaming client subsystems, such as client subsystems (306) and (308) of FIG. 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, in an electronic device (330). The video decoder (310) decodes an 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) of the example of FIG. 3.

[0043] The receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410), in the same or another embodiment, one encoded video sequence at a time, where the decoding of each encoded video sequence is independent of the other encoded video sequences. The encoded video sequences may be received from a channel (401), which may be a hardware / software link to a storage device that stores the encoded video data. The receiver (431) may receive the encoded video data along with other data, such as encoded audio data and / or auxiliary data streams, which may be forwarded to an element (not shown) that uses the respective data. The receiver (431) may separate the encoded video sequences from the other data. To combat network jitter, a buffer memory (415) may be connected between the receiver (431) and the entropy decoder / parser (420) (hereafter 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 yet 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 and may be relatively large, advantageously of adaptive size, and may be at least partially implemented 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 categories of symbols 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 supplemental enhancement information (SEI message) or a fragment of a set of video usability information (VUI) parameters (not shown). 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 video coding standard and may be according to various principles including variable length coding, Huffman coding, context-dependent arithmetic coding or context-dependent arithmetic coding, etc. 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 part thereof (e.g., inter-picture and intra-picture, inter-block and intra-block), and other factors. Which units are involved 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 a number of functional units, as described below. In an actual implementation operating under commercial constraints, many of these units may interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, 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 scalar / 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 a block 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) buffers, for example, a partially reconstructed current picture and / or a fully reconstructed current picture. The aggregator (455) may add the prediction information generated by the intra-prediction unit (452) to the output sample information provided by the scalar / 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 have been 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 compensation of the retrieved samples according to the symbols (421) related to 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 the prediction samples may be controlled by the 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, etc.

[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 filter techniques controlled by parameters contained in the coded video sequence (also called coded video bitstream) and made available to the loop filter unit (456) as symbols (421) from the parser (420), which may be responsive to meta-information obtained during decoding of 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 a coded picture corresponding to a current picture is fully reconstructed and the coded picture is identified (e.g., by the parser (420)) as a reference picture, 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 given video compression technique in a standard such as ITU-T Recommendation H.265. The encoded video sequence may conform to a syntax, which is 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. In particular, the profile may select a particular tool from all tools available in the video compression technique or standard as the only tool usable under that profile. Also, compliance may require that the complexity of the encoded video sequence be within a range defined by a level of the video compression technique or standard. In some cases, the level limits a maximum picture size, a maximum frame rate, a maximum reconstructed sample rate (e.g., measured in megasamples per second), a maximum reference picture size, etc. The limits set by the levels may possibly be further constrained by 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 example video encoder (303) 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 CrCb4:2:0, Y CrCb4:4:4). In a media serving system, the video source (501) may be a storage device that stores pre-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 a number of individual pictures that, when viewed in succession, 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 appreciate the relationship between pixels and samples. In the following description, emphasis is placed 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 constraint 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 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 oversimplified explanation, in one example, the encoding loop may include a source encoder (530) (e.g., responsible for generating symbols, such as a symbol stream, based on an input picture to be encoded and a reference picture) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a similar manner as the (remote) decoder would do (since in the video compression techniques contemplated in 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). Since the decoding of the symbol stream produces bit-for-bit accurate results regardless of the location of the decoder (local or remote), the contents in the reference picture memory (534) are also bit-for-bit accurate between the local and remote encoders. In other words, what the predictor of the encoder "sees" as a reference picture are exactly the 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 the same as that of a "remote" decoder, such as the video decoder (410) already described in detail above in connection with Figure 4. However, with brief reference also to Figure 4, because symbols are available and the encoding / decoding of symbols into the encoded video sequence by the entropy encoder (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 above discussion is that any decoder technique, other than analysis / entropy decoding, present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter focuses on the decoder operation. A description of the encoder technique can be omitted since it is the inverse of the decoder technique described generically. Only in certain areas is more detailed description required and is provided below.

[0063] During operation, in some examples, the source encoder (530) may perform motion-compensated predictive encoding, which predictively encodes an input picture with reference to one or more previously encoded pictures from the 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 encoded video data of pictures that may be designated as reference pictures based on symbols created by the source encoder (530). The operation of the encoding engine (532) may advantageously be a lossy process. When the encoded video data may be decoded in a video decoder (not shown in FIG. 5), the reconstructed video sequence may be a replica of the source video sequence, usually with some errors. The local video decoder (533) may replicate the decoding process that may be performed by the video decoder on the reference pictures and may cause the reconstructed reference pictures to be stored in a reference picture cache (534). In this way, the video encoder (503) may locally store copies of reconstructed reference pictures that have common content (in the absence of transmission errors) as the reconstructed reference pictures obtained by the far-end video decoder.

[0065] The predictor (535) may perform a prediction 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 for certain metadata of the reference picture, such as motion vectors, block shapes, etc., 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 a suitable prediction reference. 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, arithmetic coding, etc.

[0068] The sender (540) may buffer the encoded video sequence produced by the entropy encoder (545) and prepare it for transmission over a channel (560), which may be a hardware / software link to a storage device that stores the encoded video data. The sender (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] A controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a particular encoded picture type to each encoded picture, which may affect the encoding 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 Decoded 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 encoded and decoded using intra- or inter-prediction, which uses at most one motion vector and one reference index to predict sample values ​​for each block.

[0072] A bidirectionally predicted picture (B-picture) may be a picture that may be encoded and decoded using intra- or inter-prediction, which uses up to two motion vectors and two reference indexes 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 may generally be spatially subdivided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples, respectively) and coded block by block. A block may be predictively coded with reference to other (already coded) blocks determined by a coding assignment applied to the respective picture of the block. For example, a block of an I picture may be non-predictively coded or may be predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). A pixel block of a P picture may be predictively coded via spatial or temporal prediction with reference to one previously coded reference picture. A block 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 given video encoding technique or standard, such as ITU-T Recommendation H.265, in which 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 VUI parameter sets, etc.

[0076] Video may be captured in a time sequence as multiple source pictures (video pictures). Intra-picture prediction (often abbreviated as intra prediction) exploits spatial correlation in a given picture, while inter-picture prediction exploits inter-picture (temporal or other) correlation. In one example, a particular picture being coded / decoded, called 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 in 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, bi-prediction techniques may be used in inter-picture prediction. According to bi-prediction techniques, 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, to improve coding efficiency, merge mode techniques can be used in inter-picture prediction.

[0079] According to some embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed on a block-by-block basis. For example, according to the HEVC standard, pictures in a sequence of video pictures are partitioned into coding tree units (CTUs) for compression, and the CTUs in a picture have the same size, such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU includes three coding tree blocks (CTBs), one luma CTB and two chroma CTBs. Each CTU can be recursively quad-tree partitioned into one or more CUs. For example, a CTU of 64×64 pixels can be partitioned into one CU of 64×64 pixels, four CUs of 32×32 pixels, or sixteen CUs of 16×16 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 partitioned into one or more prediction units (PUs) depending on temporal and / or spatial predictability. Generally, each PU includes a luma prediction block (PB) and two chroma PBs. In one embodiment, the prediction operation in coding (encoding / decoding) is performed in units of a prediction block. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of pixel values ​​(e.g., luma values), such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 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 an encoded video sequence. In one example, the video encoder (603) is used in place of the video encoder (303) of the example 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 8×8 samples. The video encoder (603) determines whether the processing block is optimally encoded using intra mode, inter mode, or bi-predictive mode, e.g., using rate-distortion optimization. If the processing block is to be encoded in intra mode, the video encoder (603) may use intra prediction techniques to encode the processing block into a coded picture. And, if the processing block is to be encoded in inter mode or bi-predictive mode, the video encoder (603) may use inter prediction or bi-predictive techniques, respectively, to encode the processing block into a coded picture. In certain other video encoding 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 encoding 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 FIG. 6, the video encoder (603) includes an inter-encoder (630), an intra-encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), an overall controller (621), and an entropy encoder (625), connected to each other as shown in FIG. 6.

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

[0084] The intra encoder (622) is configured to receive samples of a current block (e.g., a processing block), possibly compare the block with previously encoded blocks in the same picture, generate quantized coefficients after transformation, and possibly also generate intra prediction information (e.g., intra prediction direction information according to one or more intra encoding techniques). In one example, the intra encoder (622) 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 global controller (621) is configured to determine global control data and control other components of the video encoder (603) based on the global control data. In one example, the global 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 an intra mode, the global controller (621) controls the switch (626) to select an intra mode result to be used by the residual calculator (623) and controls the entropy encoder (625) to select intra prediction information and include the intra prediction information in the bitstream, and if the mode is an inter mode, the global 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 a difference (residual data) between the received block and a prediction result selected from the intra-encoder (622) or the inter-encoder (630). The residual encoder (624) is configured to operate on the residual data to encode the residual data to generate transform coefficients. In one example, the residual encoder (624) is configured to transform the residual data from the spatial domain to the frequency domain to generate transform coefficients. The transform coefficients 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 the inter-encoder (630) as appropriate. For example, the inter-encoder (630) may generate decoded blocks based on the decoded residual data and the inter-prediction information, and the intra-encoder (622) may generate decoded blocks based on the decoded residual data and the intra-prediction information. In some examples, the decoded blocks are suitably processed to generate a decoded picture, which may be buffered in a memory circuit (not shown) and used as a reference picture.

[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, the 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 to 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 FIG. 7, the video decoder (710) includes an entropy decoder (771), an inter-decoder (780), a residual decoder (773), a reconstruction module (774), and an intra-decoder (772), connected together as shown in FIG. 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-predictive mode, inter mode and bi-predictive mode of the merged submode, or another submode, etc.), prediction information (e.g., intra prediction information or inter prediction information, etc.) that may identify certain samples or metadata that the intra decoder (772) or the inter decoder (780), respectively, will use for prediction, and residual information, for example in the form of quantized transform coefficients, etc. In one example, if the prediction mode is an inter prediction mode or a bi-predictive 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 to generate inter prediction results based on the inter prediction information.

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

[0093] The residual decoder (773) is configured to perform inverse quantization to extract inverse quantized transform coefficients and process the inverse quantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (773) may also require certain control information (to include quantizer parameters (QP)), which may be provided by the entropy decoder (771) (data path not shown as there may be only 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 the case may be, output by the inter prediction module or the intra prediction module) to form a reconstructed block, which may be part of a reconstructed picture, which in turn may be part of a reconstructed video. It should be noted that other suitable 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 partitions, for example 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 may be allowed for each partition; that is, each partition has one motion vector and one reference index. A uni-prediction motion constraint is applied to ensure that the triangular partitions are the same as traditional 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-1D.

[0098] When a TPM is used for the current CU, a flag indicating the TPM's orientation (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 syntax binarization of the TPM merge indices can be specified. After predicting each of the triangular 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, transformation and quantization processes can be further 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 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-prediction candidate list may be derived directly from the merge candidate list constructed according to the extended merge prediction process. Denote the index of a uni-prediction motion in the triangle uni-prediction candidate list 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-prediction motion vector for the TPM. These motion vectors are marked with "X" in FIG. 9. If the corresponding LX motion vector of the N extended merge candidates does not exist, the L(1-X) motion vectors of the same candidate are used instead as the uni-prediction motion vectors for the TPM.

[0101] II.2 Blending along triangulation edges After predicting each triangle partition 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, the motion vectors of 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), then Mv1 and Mv2 are simply combined to form a bi-predictive motion vector. Otherwise, if Mv1 and Mv2 are from the same list, then only the uni-predictive motion Mv2 is stored.

[0103] III. Geometric Merge Mode (GEO) The techniques related to Geometric Merge Mode (GEO) are described in (i)-(iii), which are summarized in (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, (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. The following documents are incorporated herein by reference: JVET-P0068, JVET-P0884, and JVET-P0085.

[0104] The Geometric Merge Mode (GEO), also known as the 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°, equally spaced 11.25° apart) and 5 edges relative to the center of the CU.

[0105] FIG. 11 shows an exemplary GEO. In FIG. 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 ρ represents the quantized offset of max The value of may be derived geometrically by Equation 5 for either w or h scaled with the short edge length equal to 8 and 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 boundaries from getting too close to the corners of the current block.

[0106]

number

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

[0108] IV. Weighted Sample Prediction Processing for GEO IV.1 Mixed weight calculation In GEO, the final sample predictor P B may be derived using two 3-bit blending masks (ie, weights or weighting coefficients) W0 and W1 and two predictors P0 and P1 according to Equation 6. 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 indexes. The blending weighting indexes (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 GEO with angle φ, and i <nである。

[0112] Finally, the sample blend 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. The 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. The 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, otherwise 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 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, which has 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, then the variable partIdx may be set to weightIdx>0.

[0125] 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].

[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 blend masks, the minimal blend mask storage method can achieve 84-91% memory requirement reduction for blend weight storage.

[0131] g_sampleWeight L Let [] denote the predefined masks for blending weights. Let N denote the number of predefined masks in each set, and assume that N is set to NA≫1, where NA is the number of angles supported in GEO. M×M denote the size of the predefined masks for blending weights, where M is set to 128+((ND-1)×(128≫S))≪1, where ND is the number of steps supported in GEO, and S is set to ND-1. For 32 angles with 5-step setting, N is set to 16 and M is set to 192. For 24 angles with 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 minimal blending 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 the 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, otherwise 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] The 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, which represents 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 the 4×4 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 the 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] If merge_geo_flag[xCb][yCb]=1, then sType=motionIdx[xSbIdx][ySbIdx], where xSbIdx=0..numSbX-1, ySbIdx=0..numSbY-1.

[0153] V.2 Simplified motion vector storage process In some cases, the motion vector storage process is further simplified. The distance between the center position of the 4x4 motion storage unit and the division boundary may 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 of the blend 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 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 values ​​using a lookup table, designated 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 true, 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 the motion field storage, the process may derive all information from a predefined mask for the mask of the 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 of 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=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 a lookup table designated Dis as 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 decisions 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 realized using a lookup table. The other two lookup tables include a cos[.] value lookup table and a conversion table for converting the mix weight index to a mix weight value. Therefore, it is computationally demanding to calculate the mix weight mask and the motion vector type mask for each GEO coded block on-the-fly.

[0169] To reduce computational complexity, in some examples, the mixed weight mask and the motion vector storage type mask may be calculated and stored in memory in advance. However, the huge memory storage size is a design challenge. Taking the 140 mode variant of GEO as an example, the memory required to store the 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: (2x2 + 2x4 + 2x8 + 2x16 + 4x2 + 4x4 + 4x8 + 4x16 + 8x2 + 8x4 + 8x8 + 8x16 + 16x2 + 16x4 + 16x8 + 16x16 + 16x32 + 32x16 + 32x32) 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 partitioning modes, in practical implementations, it may be difficult to store all adaptive weights and motion vector type masks for motion field storage for each block size and partitioning 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 practical implementations, the amount of memory required is still large. If N is N A ≫1, 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 are 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. The techniques in these embodiments allow for on-the-fly weighting coefficient calculations and motion vector storage type determination using a small lookup table of trigonometric function values ​​(e.g., cosine values).

[0176] As mentioned above, the blending weight mask for the geometric merge mode may be derived from the sample positions and split boundary distances using a lookup table having 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 intended to avoid partition boundaries being too close to the corners of the current coding block. As an example, ρ for an 8×8 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 Eq. margin is used to avoid partition boundaries (partition edges) being too close to the corners 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 division 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 range offset ρ can be simplified as follows:

[0183]

number

[0184] Thus, the calculation of the distance offset ρ can be accomplished by shift, multiply, and add operations in addition to the cosine value lookup table operation. margin This 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 large tables to store the blend weight masks.

[0186] Based on Equation 18 above, the GEO blending mask derived from the distance from the sample positions to the splitting 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 two, then 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. And Equation 20 shows 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 range.

[0192] For example, each cosine value in the cos[.] lookup table may be realized as an m-bit fixed-point value, where m may be a positive value such as 6 or 3. In addition, the sample center point is also adopted for digital images with discrete sampling for mixed weight index calculation. The weight index wIdx(x,y) is calculated by multiplying the weight index by 2 to avoid floating-point arithmetic 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 a relatively high degree of precision.

[0193]

number

[0194] If the distance step number n is a power of 2, then 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] 4-quadrant angles In one embodiment, the weighted index calculation may be performed using different formulas depending on the quadrant of the split boundary angle φ. For example, for the split boundary calculation, cos(φ) and

[0197]

number

[0198] Both values ​​of 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 on row-wise and column-wise basis 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 weight index wIdx(x,y) may be derived from the mixed weight index of the adjacent left pixel of 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 weight index values ​​is needed for mask storage. The other columns of weight indexes may be determined by using the mixed weight 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 a position (x,y) of a coding block may be derived from a particular weighted index value wIdx(0,0) (which may be determined based on the block size, the distance offset ρ, and the partition angle φ) depending on the coordinates (x,y) and the cosine table. In this manner, 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 for each sample in the block may be calculated in parallel with Equation 32.

[0215] Converting weighted indices 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 allow for 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) (Eq.37)

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

[0222] Motion index calculation without lookup table - Patents.com In one embodiment, a calculation method that does not use 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 partition distance offset ρ (denoted by n and i) of the current coding block, the partition 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, the motion vector storage process may be derived on the fly using the distance between the center position of the motion storage unit (subblock) and the partition boundary without utilizing a motion storage process such as TPM. The motion storage unit may have a size of 4x4 samples, or other subblock sizes (e.g., 8x8 samples). The center position of the WxH subblock may be defined as an integer position in (W / 2, H / 2), or (W / 2-1, H / 2-1), or a neighboring position of these integer positions. Alternatively, the subpel position ((W-1) / 2.0, (H-1) / 2.0) may be defined as the center position. The aforementioned 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. Thus, the dependency between the blend mask and the motion storage can be removed.

[0224] In one example, the motion storage unit (sub-block) has a size of 4×4 samples. sb and y sb The variable x specifies the position of the 4×4 sub-block of the current w×h coding block in the horizontal and vertical directions. sb and y sb is an expression, 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, in Equation 38, the distance between the center position of the 4×4 motion store unit and the partition boundary may be derived.

[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 a relatively high degree of precision.

[0227]

number

[0228] Motion index derived from blended weighted index In one embodiment, the motion storage unit (sub-block) motionIdx(x sb ,y sb The motion index, denoted by , is derived directly from the mixed weighted index of the sample position in 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 weight index may be derived from the distance between the sample and the partition boundary. Thus, the motion index may be estimated from the blending weight index of the sample that is within the corresponding sub-block and may not be located at the center of the sub-block.

[0230] In one example, the estimation is accomplished 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 4×4 samples. The coordinates of the sample position in 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 that is specified to calculate 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 having 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 the 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 the 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. Compared to calculating the motion index based on the distance from the center sample position in the motion storage unit to the partition edge, the computational complexity can be reduced.

[0237] VII. EXEMPLARY PROCESSING OF GEOMETRIC PARTITIONING MODE 12 shows a flow chart 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) starts at (S1201) and proceeds to (S1210).

[0238] At (S1210), syntax elements may be received from a bitstream of 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 partition 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 of the table) that applies to the current coding block, and two GPM merge indexes corresponding to the first and second portions of the current coding block.

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

[0240] In (S1230), for the first motion storage unit of the motion field of the current coding block, a stored motion vector type 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 in (S1220) is used as the motion index of the first motion storage unit. For example, the weighted index determined in (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 computation 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 part of the geometric partition, MV2 from the second part of the geometric partition, and a combined MV of MV1 and MV2 are stored in the motion field for the first motion storage unit. The 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 including instructions that may be executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or 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, smart phones, 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 the 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), 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 obtained from a still image camera), 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 touch screen (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. Such human interface output devices may stimulate one or more of the senses of a human user, 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 touch screen (1310), data gloves (not shown), or joystick (1305), although there may also be haptic feedback devices that do not function as input devices), audio output devices (e.g., speakers (1309), headphones (not shown)), visual output devices (e.g., screens (1310) including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input capability, each with or without haptic feedback capability, some of which may be capable of outputting two-dimensional visual output or three or more 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 (such as 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 tapes 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, optical. Additionally, 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, wireless LAN, etc., 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, vehicular 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 as described below (e.g., an Ethernet interface to a PC computer system, or a mobile communications network interface to a smartphone computer system). 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 a core (1340) of the computer system (1300).

[0253] The cores (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 areas (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), internal mass storage (1347) such as an internal, non-user accessible hard drive, SSD, etc. 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 certain instructions that may combine to constitute the aforementioned computer code. That computer code may be stored in a ROM (1345) or a RAM (1346). Transient data may also be stored in a RAM (1346), while persistent data may be stored, for example, in an internal mass storage (1347). Rapid storage and retrieval in any of the memory devices may be enabled by the use of cache memories, which may be closely associated with one or more CPUs (1341), one or more GPUs (1342), one or more mass storages (1347), one or more ROMs (1345), one or more RAMs (1346), and the like.

[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 the 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 previously described, as well as media associated with specific storage of the cores (1340) of a non-transitory nature, such as the core internal mass storage (1347) or ROM (1345). Software implementing various embodiments of the present disclosure may be stored in 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 processes defined by the software. Additionally, or alternatively, the 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 particular 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 suitable combination of hardware and software.

[0257] While this disclosure has described several exemplary embodiments, there are modifications, substitutions, and various alternative equivalents that are included within the scope of the disclosure. Thus, it will 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 disclosure and are thus within the spirit and scope of the disclosure.

[0258] Appendix A: Acronyms ASIC: Application Specific Integrated Circuit BMS: A 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 Symbols 430 Electronic equipment 431 Receiver 451 Scaler / Descaler Unit 452 Intra-picture Prediction Unit 453 Motion Compensation Prediction Unit 455 Aggregator 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 Sequence 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 Inter Decoder 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 mass storage 1348 System Bus 1349 Peripheral Bus 1350 Graphics Adapter 1354 Network Interface 1355 Communication Network

Claims

1. A method of video encoding in a video encoder, comprising: generating syntax elements 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; 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 motion vector type to be stored 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; A method comprising:

2. 2. The method of claim 1, wherein the sample position of the current coding block for which the weighted index is used as the motion index of the first motion storage unit is a sample position within the first motion storage unit of the motion field of the coding block.

3. 2. The method of claim 1, wherein the sample position of the current coding block for which the weighted index is used as the motion index of the first motion storage unit is the motion index of the first motion storage unit that is close to a central position of the first motion storage unit of the motion field of the coding block.

4. 2. The method of claim 1, wherein 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 of the first motion storage unit is the sample position at coordinates (2, 2) within the first motion storage unit of the motion field of the coding block.

5. the first motion storage unit has a size of 4x4 samples and is located at a position (x_sb, y_sb) in the motion field of the current coding block, and the sample position of the current coding block has coordinates of ((x_sb<<2)+2, (y_sb<<2)+2) of the current coding block; The method of claim 1 , wherein the weighted index of the ((x_sb<<2)+2, (y_sb<<2)+2) coordinate is used as the motion index of the first motion storage unit.

6. 2. The method of claim 1, further comprising: performing a calculation to convert the weighted indexes at the sample positions of the current coding block into the mixing weights for mixing the two prediction signals, the conversion being based on a linear function of the weighted indexes at the sample positions of the current coding block without using a look-up table.

7. A method of video encoding in a video encoder, comprising: generating a video bitstream; storing the video bitstream; The step of generating a video bitstream comprises: generating syntax elements 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; 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 motion vector type to be stored 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; method.

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