Method for video encoding, computing device, non-transitory computer-readable storage medium, computer program product, and method for storing bitstream

Abstract

A method for video encoding, a computing device, a non-transitory computer-readable storage medium, a computer program product, and a method for storing a bitstream are provided. A computing device performs a method for decoding video data by the following operations: determining a co-located picture of a current coding unit; locating a spatially adjacent block of the current coding unit corresponding to the co-located picture; determining a motion shift vector of the current coding unit from one or more motion vectors associated with the spatially adjacent blocks according to a predefined fixed order; and reconstructing a sub-block-based temporal motion vector of a corresponding sub-block among a plurality of sub-blocks in the current coding unit from a corresponding sub-block in the co-located picture based on the motion shift vector.

Description

[0001] This application is a divisional application of the invention application with application number 202080036321.0, application date June 5, 2020, and title “Sub-block temporal motion vector prediction for video encoding and decoding”. Technical Field

[0002] The present application relates generally to video data encoding and decoding, and in particular, to methods and systems for sub-block motion vector prediction during video data encoding and decoding. Background Art

[0003] Various electronic devices (such as digital televisions, laptop or desktop computers, tablet computers, digital cameras, digital recording devices, digital media players, video game consoles, smart phones, video teleconferencing devices, video streaming devices, etc.) support digital video. Electronic devices transmit, receive, encode, decode and / or store digital video data by implementing video compression / decompression standards defined by MPEG-4, ITU-T H.263, ITU-TH.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), High Efficiency Video Coding (HEVC) and Versatile Video Coding (VVC) standards. Video compression typically includes performing spatial (intra-frame) prediction and / or temporal (inter-frame) prediction to reduce or remove the redundancy inherent in video data. For block-based video coding, a video frame is divided into one or more strips, each strip having multiple video blocks, which may also be referred to as coding tree units (CTUs). Each CTU may contain a coding unit (CU) or may be recursively split into smaller CUs until a predefined minimum CU size is reached. Each CU (also called a leaf-CU) contains one or more transform units (TUs) and each CU also contains one or more prediction units (PUs). Each CU can be encoded in intra, inter, or IBC mode. Video blocks in an intra-coded (I) slice of a video frame are encoded using spatial predictions about reference samples in neighboring blocks within the same video frame. Video blocks in an inter-coded (P or B) slice of a video frame can use spatial predictions about reference samples in neighboring blocks within the same video frame or temporal predictions about reference samples in other previous reference video frames and / or future reference video frames.

[0004] A prediction block for the current video block to be encoded is derived based on spatial prediction or temporal prediction of previously encoded reference blocks (e.g., neighboring blocks). The process of finding the reference block can be accomplished by a block matching algorithm. The residual data representing the pixel differences between the current block to be encoded and the prediction block is called a residual block or prediction error. Inter-coded blocks are encoded based on the residual block and a motion vector pointing to a reference block in a reference frame that forms the prediction block. The process of determining the motion vector is generally referred to as motion estimation. Intra-coded blocks are encoded based on the intra-frame prediction mode and the residual block. For further compression, the residual block is transformed from the pixel domain to the transform domain (e.g., the frequency domain) to obtain residual transform coefficients, which can then be quantized. The quantized transform coefficients, initially arranged in a two-dimensional array, can be scanned to produce a one-dimensional vector of transform coefficients, which are then entropy encoded into a video bitstream to achieve even greater compression.

[0005] The encoded video bitstream is then stored in a computer-readable storage medium (e.g., a flash memory) for access by another electronic device with digital video capabilities or sent directly to the electronic device by wire or wirelessly. The electronic device then performs video decompression (which is the reverse process of the video compression described above), for example, by parsing the encoded video bitstream to obtain semantic elements from the bitstream, and reconstructing digital video data from the encoded video bitstream to its original format based at least in part on the semantic elements obtained from the bitstream, and the electronic device presents the reconstructed digital video data on a display of the electronic device.

[0006] As digital video quality changes from HD to 4K×2K or even 8K×4K, the amount of video data to be encoded / decoded increases exponentially. How to encode / decode video data more efficiently while maintaining the image quality of the decoded video data is a long-standing challenge. Summary of the invention

[0007] The present application describes embodiments related to video data encoding and decoding, and more particularly, describes embodiments related to systems and methods for sub-block motion vector prediction.

[0008] According to the first aspect of the present application, a method for decoding a current coding unit in a current picture comprises: determining a co-located picture of the current picture; determining a motion shift vector of the current coding unit according to motion vectors of spatially neighboring blocks of the current coding unit, wherein the motion shift vector indicates a shift in spatial position between a sub-block of a plurality of sub-blocks in the current coding unit in the current picture and a corresponding sub-block in the co-located picture; and reconstructing a sub-block-based temporal motion vector of the sub-block of the plurality of sub-blocks in the current coding unit from the corresponding sub-block in the co-located picture based on the motion shift vector.

[0009] According to a second aspect of the present application, a computing device includes one or more processors, a memory, and a plurality of programs stored in the memory. When the programs are executed by the one or more processors, the computing device performs the operations described above.

[0010] According to a third aspect of the present application, a non-transitory computer-readable storage medium stores a plurality of programs for execution by a computing device having one or more processors. When the programs are executed by the one or more processors, the computing device performs the operations described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of the specification, illustrate the described embodiments and together with the description serve to explain the basic principles. Like reference numerals refer to corresponding parts.

[0012] Figure 1 is a block diagram illustrating an exemplary video encoding and decoding system according to some embodiments of the present disclosure.

[0013] Figure 2 is a block diagram illustrating an exemplary video encoder according to some embodiments of the present disclosure.

[0014] Figure 3 is a block diagram illustrating an exemplary video decoder according to some embodiments of the present disclosure.

[0015] FIG. 4A to FIG. 4E is a block diagram illustrating how a frame may be recursively partitioned into multiple video blocks of different sizes and shapes according to some embodiments of the present disclosure.

[0016] Figure 5 is a block diagram illustrating spatial neighboring positions and temporal co-located block positions of a current CU to be encoded according to some embodiments of the present disclosure.

[0017] FIG. 6A to FIG. 6D is a block diagram illustrating steps for deriving a temporal motion vector prediction value for a current block or a sub-block temporal motion vector prediction value for a sub-block in the current block according to some embodiments of the present disclosure.

[0018] Figure 7 A block diagram for determining a valid region for deriving a temporal motion vector predictor and a sub-block temporal motion vector predictor according to some embodiments of the present disclosure is shown.

[0019] FIG. 8A to FIG. 8B A flow chart illustrating an exemplary process for a video codec to implement a technique for deriving sub-block temporal motion vector predictors according to some embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to specific embodiments, examples of which are shown in the accompanying drawings. In the following detailed description, numerous non-limiting specific details are set forth to aid in understanding the subject matter presented herein. However, it will be apparent to one of ordinary skill in the art that various alternatives may be used without departing from the scope of the claims, and that the subject matter may be practiced without these specific details. For example, it will be apparent to one of ordinary skill in the art that the subject matter presented herein may be implemented on many types of electronic devices having digital video capabilities.

[0021] Figure 1 is a block diagram illustrating an exemplary system 10 for encoding and decoding video blocks in parallel according to some embodiments of the present disclosure. Figure 1 As shown in , system 10 includes a source device 12 that generates and encodes video data to be later decoded by a destination device 14. Source device 12 and destination device 14 may include any of a wide variety of electronic devices, including desktop or laptop computers, tablet computers, smart phones, set-top boxes, digital televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some implementations, source device 12 and destination device 14 are equipped with wireless communication capabilities.

[0022] In some embodiments, the target device 14 may receive the encoded video data to be decoded via the link 16. The link 16 may include any type of communication medium or device capable of moving the encoded video data from the source device 12 to the target device 14. In one example, the link 16 may include a communication medium that enables the source device 12 to send the encoded video data directly to the target device 14 in real time. The encoded video data may be modulated according to a communication standard (such as a wireless communication protocol) and sent to the target device 14. The communication medium may include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form a portion of a packet-based network (e.g., a local area network, a wide area network, or a global network such as the Internet). The communication medium may include a router, a switch, a base station, or any other device that may be useful in facilitating communication from the source device 12 to the target device 14.

[0023] In some other embodiments, the encoded video data may be sent from the output interface 22 to the storage device 32. Subsequently, the encoded video data in the storage device 32 may be accessed by the target device 14 via the input interface 28. The storage device 32 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, a Blu-ray disc, a DVD, a CD-ROM, a flash memory, a volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data. In another example, the storage device 32 may correspond to a file server or another intermediate storage device that can hold the encoded video data generated by the source device 12. The target device 14 may access the stored video data from the storage device 32 via streaming or downloading. The file server may be any type of computer capable of storing encoded video data and sending the encoded video data to the target device 14. Exemplary file servers include web servers (e.g., for websites), FTP servers, network attached storage (NAS) devices, or local disk drives. The target device 14 may access the encoded video data through any standard data connection suitable for accessing encoded video data stored on a file server, including a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., DSL, cable modem, etc.), or a combination of both wireless channels and wired connections. The transmission of the encoded video data from the storage device 32 may be a streaming transmission, a download transmission, or a combination of both streaming transmission and download transmission.

[0024] like Figure 1 As shown in , source device 12 includes video source 18, video encoder 20 and output interface 22. Video source 18 may include sources such as or a combination of such sources: a video capture device (e.g., a camera), a video archive containing previously captured video, a video feed interface for receiving video from a video content provider, and / or a computer graphics system for generating computer graphics data as source video. As an example, if video source 18 is a camera of a security monitoring system, source device 12 and target device 14 may form a camera phone or a video phone. However, the embodiments described in this application are generally applicable to video encoding / decoding and may be applied to wireless and / or wired applications.

[0025] The captured, pre-captured, or computer-generated video may be encoded by the video encoder 20. The encoded video data may be sent directly to the target device 14 via the output interface 22 of the source device 12. The encoded video data may also (or alternatively) be stored on a storage device 32 for later access by the target device 14 or other devices for decoding and / or playback. The output interface 22 may further include a modem and / or a transmitter.

[0026] Target device 14 includes input interface 28, video decoder 30, and display device 34. Input interface 28 may include a receiver and / or a modem and receives encoded video data via link 16. The encoded video data communicated via link 16 or provided on storage device 32 may include various semantic elements generated by video encoder 20 for use by video decoder 30 in decoding the video data. Such semantic elements may be included in the encoded video data sent over a communication medium, stored on a storage medium, or stored on a file server.

[0027] In some implementations, the target device 14 may include a display device 34, which may be an integrated display device or an external display device configured to communicate with the target device 14. The display device 34 displays the decoded video data to a user and may include any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0028] The video encoder 20 and the video decoder 30 may operate according to a proprietary standard or an industry standard (e.g., VVC, HEVC, MPEG-4, Part 10, Advanced Video Coding (AVC)) or an extension of such a standard. It should be understood that the present application is not limited to a specific video encoding / decoding standard and may be applicable to other video encoding / decoding standards. It is generally believed that the video encoder 20 of the source device 12 may be configured to encode video data according to any of these current standards or future standards. Similarly, it is also generally believed that the video decoder 30 of the target device 14 may be configured to decode video data according to any of these current standards or future standards.

[0029] The video encoder 20 and the video decoder 30 may be implemented as any of a variety of suitable encoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When partially implemented in software, the electronic device may store instructions for the software in a suitable non-transitory computer-readable medium and use one or more processors to execute the instructions in the hardware to perform the video encoding / decoding operations disclosed in the present disclosure. Each of the video encoder 20 and the video decoder 30 may be included in one or more encoders or decoders, and either of the encoders or decoders may be integrated as part of a combined encoder / decoder (CODEC) in the corresponding device.

[0030] Figure 2is a block diagram illustrating an exemplary video encoder 20 according to some embodiments described herein. The video encoder 20 may perform intra-frame prediction encoding and inter-frame prediction encoding of video blocks within a video frame. Intra-frame prediction encoding relies on spatial prediction to reduce or remove spatial redundancy in video data within a given video frame or picture. Inter-frame prediction encoding relies on temporal prediction to reduce or remove temporal redundancy in video data within adjacent video frames or pictures of a video sequence.

[0031] like Figure 2 As shown in FIG. 1 , the video encoder 20 includes a video data memory 40, a prediction processing unit 41, a decoded picture buffer (DPB) 64, an adder 50, a transform processing unit 52, a quantization unit 54, and an entropy coding unit 56. The prediction processing unit 41 further includes a motion estimation unit 42, a motion compensation unit 44, a segmentation unit 45, an intra-frame prediction processing unit 46, and an intra-frame block copy (BC) unit 48. In some embodiments, the video encoder 20 also includes an inverse quantization unit 58, an inverse transform processing unit 60, and an adder 62 for video block reconstruction. A deblocking filter (not shown) may be located between the adder 62 and the DPB 64 to filter the block boundaries to remove block artifacts from the reconstructed video. In addition to the deblocking filter, a loop filter (not shown) may also be used to filter the output of the adder 62. The video encoder 20 may take the form of a fixed or programmable hardware unit, or may be dispersed in one or more of the illustrated fixed or programmable hardware units.

[0032] Video data memory 40 may store video data to be encoded by components of video encoder 20. The video data in video data memory 40 may be obtained, for example, from video source 18. DPB 64 is a buffer that stores reference video data for use by video encoder 20 (e.g., in intra-frame or inter-frame prediction coding mode) when encoding video data. Video data memory 40 and DPB 64 may be formed by any of a variety of memory devices. In various examples, video data memory 40 may be on-chip with other components of video encoder 20, or off-chip relative to those components.

[0033] like Figure 2As shown in , after receiving the video data, the segmentation unit 45 within the prediction processing unit 41 segments the video data into video blocks. This segmentation may also include segmenting the video frame into slices, tiles, or other larger coding units (CUs) according to a predefined splitting structure associated with the video data (such as a quadtree structure). The video frame may be divided into a plurality of video blocks (or a set of video blocks referred to as partitions). The prediction processing unit 41 may select one of a plurality of feasible prediction coding modes for the current video block based on error results (e.g., coding rate and distortion level), such as one of one or more inter-frame prediction coding modes in a plurality of intra-frame prediction coding modes. The prediction processing unit 41 may provide the resulting intra-frame prediction coding block or inter-frame prediction coding block to the adder 50 to generate a residual block, and to the adder 62 to reconstruct the coding block for subsequent use as part of a reference frame. The prediction processing unit 41 also provides semantic elements (such as motion vectors, intra-frame mode indicators, segmentation information, and other such semantic information) to the entropy coding unit 56.

[0034] To select an appropriate intra-prediction coding mode for the current video block, intra-prediction processing unit 46 within prediction processing unit 41 may perform intra-prediction coding of the current video block in relation to one or more neighboring blocks in the same frame as the current block to be encoded to provide spatial prediction. Motion estimation unit 42 and motion compensation unit 44 within prediction processing unit 41 may perform inter-prediction coding of the current video block in relation to one or more prediction blocks in one or more reference frames to provide temporal prediction. Video encoder 20 may perform multiple encoding passes, for example, to select an appropriate coding mode for each block of video data.

[0035] In some embodiments, motion estimation unit 42 determines the inter-prediction mode for a current video frame by generating a motion vector according to a predetermined pattern within a sequence of video frames, the motion vector indicating the displacement of a prediction unit (PU) of a video block within the current video frame relative to a prediction block within a reference video frame. Motion estimation performed by motion estimation unit 42 is the process of generating a motion vector that estimates the motion for a video block. For example, a motion vector may indicate the displacement of a PU of a video block within a current video frame or picture relative to a prediction block (or other coding unit) within a reference frame associated with a current block (or other coding unit) being encoded within the current frame. The predetermined pattern may designate video frames in a sequence as P frames or B frames. Intra BC unit 48 may determine a vector (e.g., a block vector) for intra BC coding in a manner similar to the motion vectors determined by motion estimation unit 42 for inter prediction, or may utilize motion estimation unit 42 to determine the block vector.

[0036] A prediction block is a block of a reference frame that is considered to closely match a PU of a video block to be encoded in terms of pixel differences, which may be determined by sum of absolute differences (SAD), sum of squared differences (SSD), or other difference metrics. In some embodiments, video encoder 20 may calculate values ​​for sub-integer pixel positions of reference frames stored in DPB 64. For example, video encoder 20 may interpolate values ​​for quarter-pixel positions, eighth-pixel positions, or other fractional pixel positions of a reference frame. Thus, motion estimation unit 42 may perform motion searches relative to full pixel positions and fractional pixel positions and output motion vectors with fractional pixel precision.

[0037] Motion estimation unit 42 calculates a motion vector for a PU of a video block in an inter-prediction coded frame by comparing the position of the PU with the position of a prediction block of a reference frame selected from a first reference frame list (list 0) or a second reference frame list (list 1), each of which identifies one or more reference frames stored in DPB 64. Motion estimation unit 42 sends the calculated motion vector to motion compensation unit 44 and then to entropy encoding unit 56.

[0038] The motion compensation performed by the motion compensation unit 44 may involve extracting or generating a prediction block based on the motion vector determined by the motion estimation unit 42. After receiving the motion vector for the PU of the current video block, the motion compensation unit 44 may locate the prediction block pointed to by the motion vector in one of the reference frame lists, retrieve the prediction block from the DPB 64, and forward the prediction block to the adder 50. The adder 50 then forms a residual video block of pixel difference values ​​by subtracting the pixel values ​​of the prediction block provided by the motion compensation unit 44 from the pixel values ​​of the current video block being encoded. The pixel difference values ​​forming the residual video block may include a luma difference component or a chroma difference component or both. The motion compensation unit 44 may also generate semantic elements associated with the video block of the video frame for use by the video decoder 30 when decoding the video block of the video frame. The semantic elements may include, for example, semantic elements defining a motion vector for identifying a prediction block, any flag indicating a prediction mode, or any other semantic information described herein. It should be noted that the motion estimation unit 42 and the motion compensation unit 44 may be highly integrated, but are described separately for conceptual purposes.

[0039] In some embodiments, the intra BC unit 48 may generate vectors and extract prediction blocks in a manner similar to that described above in conjunction with the motion estimation unit 42 and the motion compensation unit 44, but these prediction blocks are in the same frame as the current block being encoded, and these vectors are referred to as block vectors rather than motion vectors. Specifically, the intra BC unit 48 may determine the intra prediction mode to be used to encode the current block. In some examples, the intra BC unit 48 may encode the current block using various intra prediction modes, for example, during separate encoding passes, and test their performance through rate-distortion analysis. Next, the intra BC unit 48 may select a suitable intra prediction mode to use among the various tested intra prediction modes and generate an intra mode indicator accordingly. For example, the intra BC unit 48 may calculate rate-distortion values ​​for the various tested intra prediction modes using rate-distortion analysis, and select the intra prediction mode with the best rate-distortion characteristics among the tested modes as the suitable intra prediction mode to use. The rate-distortion analysis generally determines the amount of distortion (or error) between a coded block and the original uncoded block that was encoded to generate the coded block, as well as the bit rate (i.e., the number of bits) used to produce the coded block. Intra BC unit 48 may calculate ratios from the distortions and rates for the various coded blocks to determine which intra-prediction mode exhibits the best rate-distortion value for the block.

[0040] In other examples, intra BC unit 48 may use, in whole or in part, motion estimation unit 42 and motion compensation unit 44 to perform such functions for intra BC prediction in accordance with embodiments described herein. In either case, for intra block copying, a prediction block may be a block that is considered to closely match the block to be encoded in terms of pixel differences, which may be determined by sum of absolute differences (SAD), sum of square differences (SSD), or other difference metrics, and identification of the prediction block may include calculating values ​​for sub-integer pixel positions.

[0041] Regardless of whether the prediction block is from the same frame according to intra-frame prediction or from a different frame according to inter-frame prediction, video encoder 20 can form pixel difference values ​​by subtracting the pixel values ​​of the prediction block from the pixel values ​​of the current video block being encoded, thereby forming a residual video block. The pixel difference values ​​forming the residual video block may include both luma component differences and chroma component differences.

[0042] As an alternative to the inter-frame prediction performed by the motion estimation unit 42 and the motion compensation unit 44 or the intra-frame block copy prediction performed by the intra BC unit 48 as described above, the intra-frame prediction processing unit 46 may perform intra-frame prediction on the current video block. Specifically, the intra-frame prediction processing unit 46 may determine an intra-frame prediction mode for encoding the current block. To this end, the intra-frame prediction processing unit 46 may use various intra-frame prediction modes to encode the current block, for example, during separate encoding passes, and the intra-frame prediction processing unit 46 (or in some examples, the mode selection unit) may select a suitable intra-frame prediction mode from the tested intra-frame prediction modes to use. The intra-frame prediction processing unit 46 may provide information indicating the intra-frame prediction mode selected for the block to the entropy encoding unit 56. The entropy encoding unit 56 may encode the information indicating the selected intra-frame prediction mode into the bitstream.

[0043] After prediction processing unit 41 determines a prediction block for the current video block via inter-prediction or intra-prediction, adder 50 forms a residual video block by subtracting the prediction block from the current video block. The residual video data in the residual block may be included in one or more transform units (TUs) and provided to transform processing unit 52. Transform processing unit 52 transforms the residual video data into residual transform coefficients using a transform, such as a discrete cosine transform (DCT) or a conceptually similar transform.

[0044] Transform processing unit 52 may send the resulting transform coefficients to quantization unit 54. Quantization unit 54 quantizes the transform coefficients to further reduce the bit rate. The quantization process may also reduce the bit depth associated with some or all of the coefficients. The degree of quantization may be modified by adjusting a quantization parameter. In some examples, quantization unit 54 may then perform a scan of the matrix including the quantized transform coefficients. Optionally, entropy encoding unit 56 may perform the scan.

[0045] After quantization, entropy encoding unit 56 entropy encodes the quantized transform coefficients into a video bitstream using, for example, context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), semantic-based context adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding, or another entropy coding method or technique. The encoded bitstream may then be sent to video decoder 30, or archived in storage device 32 for later sending to or retrieval by video decoder 30. Entropy encoding unit 56 may also entropy encode motion vectors and other semantic elements for the current video frame being encoded.

[0046] Inverse quantization unit 58 and inverse transform processing unit 60 apply inverse quantization and inverse transform, respectively, to reconstruct the residual video block in the pixel domain for use in generating reference blocks for predicting other video blocks. As noted above, motion compensation unit 44 may generate a motion compensated prediction block from one or more reference blocks of a frame stored in DPB 64. Motion compensation unit 44 may also apply one or more interpolation filters to the prediction block to calculate sub-integer pixel values ​​for use in motion estimation.

[0047] Adder 62 adds the reconstructed residual block to the motion compensated prediction block produced by motion compensation unit 44 to produce a reference block for storage in DPB 64. The reference block may then be used as a prediction block by intra BC unit 48, motion estimation unit 42, and motion compensation unit 44 to inter-predict another video block in a subsequent video frame.

[0048] Figure 3 30 is a block diagram showing an exemplary video decoder 30 according to some embodiments of the present application. The video decoder 30 includes a video data memory 79, an entropy decoding unit 80, a prediction processing unit 81, an inverse quantization unit 86, an inverse transform processing unit 88, an adder 90, and a DPB 92. The prediction processing unit 81 further includes a motion compensation unit 82, an intra-frame prediction unit 84, and an intra-frame BC unit 85. The video decoder 30 may perform the above combined Figure 2 The encoding process is substantially the inverse of the decoding process described with respect to video encoder 20. For example, motion compensation unit 82 may generate prediction data based on motion vectors received from entropy decoding unit 80, and intra-prediction unit 84 may generate prediction data based on intra-prediction mode indicators received from entropy decoding unit 80.

[0049] In some examples, units of the video decoder 30 may be tasked to perform embodiments of the present application. In addition, in some examples, embodiments of the present disclosure may be dispersed in one or more of the multiple units of the video decoder 30. For example, the intra BC unit 85 may perform embodiments of the present application alone or in combination with other units of the video decoder 30 (such as the motion compensation unit 82, the intra prediction unit 84, and the entropy decoding unit 80). In some examples, the video decoder 30 may not include the intra BC unit 85, and the functions of the intra BC unit 85 may be performed by other components of the prediction processing unit 81 (such as the motion compensation unit 82).

[0050] The video data memory 79 may store video data, such as an encoded video bitstream, to be decoded by other components of the video decoder 30. The video data stored in the video data memory 79 may be obtained, for example, from the storage device 32, from a local video source (such as a camera), via a wired or wireless network communication of video data, or by accessing a physical data storage medium (e.g., a flash drive or hard disk). The video data memory 79 may include a coded picture buffer (CPB) that stores encoded video data from an encoded video bitstream. A decoded picture buffer (DPB) 92 of the video decoder 30 stores reference video data for use by the video decoder 30 when decoding the video data (e.g., in an intra-frame or inter-frame prediction coding mode). The video data memory 79 and the DPB 92 may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. For illustrative purposes, the video data memory 79 and the DPB 92 are shown in FIG. Figure 3 92 as two different components of video decoder 30. However, it will be apparent to those skilled in the art that video data memory 79 and DPB 92 may be provided by the same memory device or separate memory devices. In some examples, video data memory 79 may be on-chip with other components of video decoder 30, or off-chip relative to those components.

[0051] During the decoding process, the video decoder 30 receives an encoded video bitstream representing video blocks of an encoded video frame and associated semantic elements. The video decoder 30 may receive the semantic elements at the video frame level and / or the video block level. The entropy decoding unit 80 of the video decoder 30 entropy decodes the bitstream to generate quantization coefficients, motion vectors or intra-frame prediction mode indicators, and other semantic elements. The entropy decoding unit 80 then forwards the motion vectors and other semantic elements to the prediction processing unit 81.

[0052] When a video frame is encoded as an intra-prediction coded (I) frame or for intra-coded prediction blocks in other types of frames, intra-prediction unit 84 of prediction processing unit 81 may generate prediction data for a video block of the current video frame based on a signaled intra-prediction mode and reference data from a previously decoded block of the current frame.

[0053] When the video frame is encoded as an inter-frame prediction coded (i.e., B or P) frame, the motion compensation unit 82 of the prediction processing unit 81 generates one or more prediction blocks for the video block of the current video frame based on the motion vector and other semantic elements received from the entropy decoding unit 80. Each of the prediction blocks may be generated from a reference frame in one of the reference frame lists. The video decoder 30 may construct the reference frame lists, List 0 and List 1, using a default construction technique based on the reference frames stored in the DPB 92.

[0054] In some examples, when a video block is encoded according to the intra BC mode described herein, intra BC unit 85 of prediction processing unit 81 generates a prediction block for the current video block based on the block vector and other semantic elements received from entropy decoding unit 80. The prediction block may be within a reconstructed region of the same picture as the current video block as defined by video encoder 20.

[0055] The motion compensation unit 82 and / or the intra BC unit 85 determine prediction information for a video block of the current video frame by parsing the motion vector and other semantic elements, and then use the prediction information to generate a prediction block for the current video block being decoded. For example, the motion compensation unit 82 uses some of the received semantic elements to determine a prediction mode (e.g., intra prediction or inter prediction) for encoding a video block of a video frame, an inter prediction frame type (e.g., B or P), construction information for one or more of the reference frame lists for the frame, motion vectors for each inter prediction encoded video block of the frame, inter prediction states for each inter prediction encoded video block of the frame, and other information for decoding a video block in the current video frame.

[0056] Similarly, the intra BC unit 85 may use some of the received semantic elements, such as flags, to determine whether the current video block is predicted using intra BC mode, construction information of which video blocks of the frame are within the reconstruction region and should be stored in the DPB 92, block vectors for each intra BC predicted video block of the frame, intra BC prediction status for each intra BC predicted video block of the frame, and other information for decoding the video block in the current video frame.

[0057] Motion compensation unit 82 may also perform interpolation using interpolation filters as used by video encoder 20 during encoding of the video block to calculate interpolated values ​​for sub-integer pixels of a reference block. In this case, motion compensation unit 82 may determine the interpolation filters used by video encoder 20 from the received syntax elements and use these interpolation filters to produce the prediction block.

[0058] Inverse quantization unit 86 inverse quantizes the quantized transform coefficients provided in the bitstream and entropy decoded by entropy decoding unit 80, using the same quantization parameters calculated by video encoder 20 for each video block in the video frame to determine the degree of quantization. Inverse transform processing unit 88 applies an inverse transform (e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to the transform coefficients to reconstruct the residual block in the pixel domain.

[0059] After the motion compensation unit 82 or the intra BC unit 85 generates a prediction block for the current video block based on the vector and other semantic elements, the adder 90 reconstructs the decoded video block for the current video block by adding the residual block from the inverse transform processing unit 88 to the corresponding prediction block generated by the motion compensation unit 82 and the intra BC unit 85. A loop filter (not shown) may be located between the adder 90 and the DPB 92 to further process the decoded video block. The decoded video block in a given frame is then stored in the DPB 92, which stores reference frames for subsequent motion compensation of the next video block. The DPB 92 or a memory device separate from the DPB 92 may also store the decoded video for later presentation on a display device (e.g., Figure 1 on a display device 34).

[0060] In a typical video encoding process, a video sequence usually includes an ordered set of frames or pictures. Each frame may include three sample arrays, denoted as SL, SCb, and SCr. SL is a two-dimensional array of luma samples. SCb is a two-dimensional array of Cb chroma samples. SCr is a two-dimensional array of Cr chroma samples. In other cases, a frame may be monochrome and therefore include only a two-dimensional array of luma samples.

[0061] like Figure 4A As shown in , the video encoder 20 (or more specifically, the segmentation unit 45) generates an encoded representation of a frame by first segmenting the frame into a set of coding tree units (CTUs). A video frame may include an integer number of CTUs ordered consecutively from left to right and from top to bottom in a raster scan order. Each CTU is the largest logical coding unit, and the width and height of the CTU are signaled by the video encoder 20 in a sequence parameter set so that all CTUs in a video sequence have the same size, one of 128×128, 64×64, 32×32, and 16×16. It should be noted, however, that the present application is not necessarily limited to a particular size. As Figure 4BAs shown in , each CTU may include one coding tree block (CTB) of luma samples, two corresponding coding tree blocks of chroma samples, and semantic elements for encoding the samples of the coding tree blocks. The semantic elements describe the properties of different types of units of the coding pixel blocks and how the video sequence can be reconstructed at the video decoder 30, including inter-frame prediction or intra-frame prediction, intra-frame prediction mode, motion vectors, and other parameters. In a monochrome picture or a picture with three separate color planes, a CTU may include a single coding tree block and semantic elements for encoding the samples of the coding tree block. The coding tree block may be an N×N sample block.

[0062] To achieve better performance, video encoder 20 may recursively perform tree partitioning, such as binary tree partitioning, ternary tree partitioning, quadtree partitioning, or a combination of both, on the coding tree blocks of the CTU and divide the CTU into smaller coding units (CUs). Figure 4C As depicted in , the 64×64 CTU 400 is first divided into four smaller CUs, each CU having a block size of 32×32. Among the four smaller CUs, CU 410 and CU 420 are respectively divided into four CUs with a block size of 16×16. The two 16×16 CUs 430 and CU 440 are further divided into four CUs with a block size of 8×8. Figure 4D Depicted is a diagram showing Figure 4C The quadtree data structure of the final result of the partitioning process of the CTU 400 depicted in FIG. 4 corresponds to a CU of each size ranging from 32×32 to 8×8. Figure 4B Each CU may include a coding block (CB) of luma samples and two corresponding coding blocks of chroma samples of the same size frame, and semantic elements for encoding the samples of the coding block. In a monochrome picture or a picture with three separate color planes, a CU may include a single coding block and semantic structures for encoding the samples of the coding block. It should be noted that Figure 4C and Figure 4D The quadtree partitioning depicted in FIG. 1 is for illustrative purposes only, and one CTU may be split into multiple CUs based on quadtree partitioning / ternary tree partitioning / binary tree partitioning to adapt to varying local characteristics. In a multi-type tree structure, one CTU is partitioned according to a quadtree structure, and each quadtree leaf CU may be further partitioned according to a binary and ternary tree structure. Figure 4E As shown, there are five possible partitioning types for a coding block with width W and height H, namely, quadruple partitioning, horizontal binary partitioning, vertical binary partitioning, horizontal ternary partitioning, and vertical ternary partitioning.

[0063] In some embodiments, the video encoder 20 may further partition the coding block of the CU into one or more M×N prediction blocks (PBs). A prediction block is a rectangular (square or non-square) block of samples to which the same prediction (inter or intra) is applied. The prediction unit (PU) of the CU may include a prediction block of luma samples, two corresponding prediction blocks of chroma samples, and semantic elements for predicting the prediction blocks. In a monochrome picture or a picture with three separate color planes, the PU may include a single prediction block and a semantic structure for predicting the prediction block. The video encoder 20 may generate a predicted luma block, a predicted Cb block, and a predicted Cr block for the luma prediction block, the Cb prediction block, and the Cr prediction block of each PU of the CU.

[0064] Video encoder 20 may use intra prediction or inter prediction to generate a prediction block for a PU. If video encoder 20 uses intra prediction to generate a prediction block for a PU, video encoder 20 may generate the prediction block for the PU based on decoded samples of a frame associated with the PU. If video encoder 20 uses inter prediction to generate a prediction block for a PU, video encoder 20 may generate the prediction block for the PU based on decoded samples of one or more frames other than the frame associated with the PU.

[0065] After the video encoder 20 generates the predicted luma block, the predicted Cb block, and the predicted Cr block for one or more PUs of a CU, the video encoder 20 may generate a luma residual block for the CU by subtracting the predicted luma block of the CU from the original luma coding block of the CU, so that each sample in the luma residual block of the CU indicates the difference between a luma sample in one of the predicted luma blocks of the CU and a corresponding sample in the original luma coding block of the CU. Similarly, the video encoder 20 may generate a Cb residual block and a Cr residual block for the CU, respectively, so that each sample in the Cb residual block of the CU indicates the difference between a Cb sample in one of the predicted Cb blocks of the CU and a corresponding sample in the original Cb coding block of the CU, and each sample in the Cr residual block of the CU may indicate the difference between a Cr sample in one of the predicted Cr blocks of the CU and a corresponding sample in the original Cr coding block of the CU.

[0066] In addition, if Figure 4CAs shown in , the video encoder 20 may decompose the luma residual block, Cb residual block, and Cr residual block of a CU into one or more luma transform blocks, Cb transform blocks, and Cr transform blocks using quadtree partitioning. A transform block is a rectangular (square or non-square) sample block to which the same transform is applied. A transform unit (TU) of a CU may include a transform block of luma samples, two corresponding transform blocks of chroma samples, and semantic elements for transforming the transform block samples. Therefore, each TU of a CU may be associated with a luma transform block, a Cb transform block, and a Cr transform block. In some examples, the luma transform block associated with a TU may be a sub-block of the luma residual block of the CU. The Cb transform block may be a sub-block of the Cb residual block of the CU. The Cr transform block may be a sub-block of the Cr residual block of the CU. In a monochrome picture or a picture with three separate color planes, a TU may include a single transform block and a semantic structure for transforming the samples of the transform block.

[0067] The video encoder 20 may apply one or more transforms to the luma transform block of the TU to generate a luma coefficient block for the TU. The coefficient block may be a two-dimensional array of transform coefficients. The transform coefficient may be a scalar. The video encoder 20 may apply one or more transforms to the Cb transform block of the TU to generate a Cb coefficient block for the TU. The video encoder 20 may apply one or more transforms to the Cr transform block of the TU to generate a Cr coefficient block for the TU.

[0068] After generating a coefficient block (e.g., a luma coefficient block, a Cb coefficient block, or a Cr coefficient block), the video encoder 20 may quantize the coefficient block. Quantization generally refers to a process in which transform coefficients are quantized to potentially reduce the amount of data used to represent the transform coefficients, thereby providing further compression. After the video encoder 20 quantizes the coefficient block, the video encoder 20 may entropy encode a semantic element indicating the quantized transform coefficients. For example, the video encoder 20 may perform context adaptive binary arithmetic coding (CABAC) on the semantic element indicating the quantized transform coefficients. Finally, the video encoder 20 may output a bitstream including a sequence of bits that form a representation of an encoded frame and associated data, and the bitstream is stored in the storage device 32 or sent to the target device 14.

[0069] After receiving the bitstream generated by the video encoder 20, the video decoder 30 may parse the bitstream to obtain semantic elements from the bitstream. The video decoder 30 may reconstruct a frame of video data based at least in part on the semantic elements obtained from the bitstream. The process of reconstructing the video data is generally the inverse of the encoding process performed by the video encoder 20. For example, the video decoder 30 may perform an inverse transform on a coefficient block associated with a TU of the current CU to reconstruct a residual block associated with the TU of the current CU. The video decoder 30 also reconstructs the coding block of the current CU by adding samples of the prediction block for the PU of the current CU to corresponding samples of the transform block of the TU of the current CU. After reconstructing the coding block for each CU of the frame, the video decoder 30 may reconstruct the frame.

[0070] As mentioned above, video coding mainly uses two modes, namely, intra-frame prediction (or intra-frame prediction) and inter-frame prediction (or inter-frame prediction) to achieve video compression. It should be noted that IBC can be regarded as intra-frame prediction or a third mode. Between the two modes, inter-frame prediction contributes more to coding efficiency than intra-frame prediction because motion vectors are used to predict the current video block from the reference video block.

[0071] But with ever-improving video data capture technology and finer video block sizes for retaining details in video data, the amount of data required to represent the motion vector for the current frame has also increased substantially. One way to overcome this challenge is to benefit from the fact that not only a set of neighboring CUs in both the spatial and temporal domains have similar video data for prediction purposes, but also the motion vectors between these neighboring CUs are similar. Therefore, it is possible to use the motion information of spatially neighboring CUs and / or temporally co-located CUs as an approximation of the motion information (e.g., motion vector) of the current CU by exploring their spatial and temporal correlations, which is also referred to as the "motion vector predictor" (MVP) of the current CU.

[0072] Instead of combining as above Figure 2 The actual motion vector of the current CU determined by the motion estimation unit 42 is encoded into the video bitstream, and the motion vector prediction value of the current CU is subtracted from the actual motion vector of the current CU to generate a motion vector difference (MVD) for the current CU. By doing so, the motion vector determined by the motion estimation unit 42 for each CU of the frame does not need to be encoded into the video bitstream, and the amount of data used to represent motion information in the video bitstream can be significantly reduced.

[0073] Similar to the process of selecting a prediction block in a reference frame during inter-frame prediction of a coding block, both the video encoder 20 and the video decoder 30 need to adopt a set of rules for constructing a motion vector candidate list (also called a "merge list") for the current CU using those potential candidate motion vectors associated with the spatial neighboring CUs and / or temporal co-located CUs of the current CU, and then selecting a member from the motion vector candidate list as the motion vector prediction value for the current CU. By doing so, the motion vector candidate list itself does not need to be sent between the video encoder 20 and the video decoder 30, and the index of the selected motion vector prediction value within the motion vector candidate list is sufficient for the video encoder 20 and the video decoder 30 to encode and decode the current CU using the same motion vector prediction value within the motion vector candidate list.

[0074] In some embodiments, each inter-prediction CU has three motion vector prediction modes for constructing a motion vector candidate list, including an inter mode (which is also referred to as "advanced motion vector prediction" (AMVP)), a skip mode, and a merge mode. In each mode, one or more motion vector candidates may be added to the motion vector candidate list according to the algorithm described below. Ultimately, one of these motion vector candidates in the candidate list is used as the best motion vector predictor for the inter-prediction CU to be encoded into a video bitstream by the video encoder 20 or decoded from the video bitstream by the video decoder 30. In order to find the best motion vector predictor from the candidate list, a motion vector competition (MVC) scheme is introduced to select a motion vector from a given candidate set (i.e., a motion vector candidate list) of motion vectors including spatial motion vector candidates and temporal motion vector candidates.

[0075] In addition to obtaining motion vector predictor candidates from spatially neighboring CUs or temporally co-located CUs, motion vector predictor candidates can also be obtained from a so-called "history-based motion vector prediction" (HMVP) table. The HMVP table holds a predefined number of motion vector predictors, each of which has been used to encode / decode a specific CU in the same row of CTUs (or sometimes the same CTU). Due to the spatial / temporal proximity of these CUs, there is a high probability that one of the motion vector predictors in the HMVP table can be reused to encode / decode a different CU within the same row of CTUs. Therefore, it is possible to achieve higher coding efficiency by including the HMVP table in the process of constructing the motion vector candidate list.

[0076] In some embodiments, the HMVP table has a fixed length (e.g., 5) and is managed in a first-in, first-out (FIFO)-like manner. For example, when an inter-frame coded block of a CU is decoded, a motion vector is reconstructed for the CU. Because the reconstructed motion vector may be a motion vector prediction value for a subsequent CU, such a motion vector is used to update the HMVP table in real time. When updating the HMVP table, there are two scenarios: (i) the reconstructed motion vector is different from other existing motion vectors in the HMVP table or (ii) the reconstructed motion vector is the same as one of the existing motion vectors in the HMVP table. For the first scenario, if the HMVP table is not full, the reconstructed motion vector is added to the HMVP table as the latest motion vector. If the HMVP table is full, before the reconstructed motion vector is added as the latest motion vector, the oldest motion vector in the HMVP table needs to be removed from the HMVP table. In other words, in this case, the HMVP table is similar to a FIFO buffer, so that the motion information located at the head of the FIFO buffer and associated with another previous inter-frame coded block is moved out of the buffer, so that the reconstructed motion vector is attached to the tail of the FIFO buffer as the latest member in the HMVP table. For the second scenario, before adding the reconstructed motion vector as the latest motion vector to the HMVP table, the existing motion vector in the HMVP table that is substantially the same as the reconstructed motion vector is removed from the HMVP table. If the HMVP table is also maintained in the form of a FIFO buffer, the motion vector prediction value after the same motion vector in the HMVP table is shifted forward by one element to occupy the space left by the removed motion vector, and then the reconstructed motion vector is appended to the tail of the FIFO buffer as the latest member in the HMVP table.

[0077] The motion vectors in the HMVP table can be added to the motion vector candidate list under different prediction modes such as AMVP, merge, skip, etc. It has been found that the motion information of the previous inter-coded blocks stored in the HMVP table can be used for more efficient motion vector prediction even if they are not adjacent to the current block.

[0078] After selecting an MVP candidate within a given candidate set for the motion vector of the current CU, the video encoder 20 may generate one or more semantic elements for the corresponding MVP candidate and encode them into the video bitstream so that the video decoder 30 can retrieve the MVP candidate from the video bitstream using the semantic elements. Different modes (e.g., AMVP, merge, skip, etc.) have different sets of semantic elements depending on the specific mode used to construct the motion vector candidate set. For the AMVP mode, the semantic elements include an inter-frame prediction indicator (list 0, list 1, or bidirectional prediction), a reference index, a motion vector candidate index, a motion vector prediction residual signal, and the like. For the skip mode and the merge mode, only the merge index is encoded into the bitstream because the current CU inherits other semantic elements including the inter-frame prediction indicator, the reference index, and the motion vector from the neighboring CU referred to by the encoded merge index. In the case of skip coding the CU, the motion vector prediction residual signal is also omitted.

[0079] Figure 5 is a block diagram showing the spatial neighboring block positions and temporal co-located block positions of the current CU to be encoded / decoded according to some embodiments of the present disclosure. For a given mode, a motion vector prediction (MVP) candidate list is constructed by first checking the availability of motion vectors associated with the left spatial neighboring block positions and the upper spatial neighboring block positions and the availability of motion vectors associated with the temporal co-located block positions, and then checking the motion vectors in the HMVP table. During the process of constructing the MVP candidate list, some redundant MVP candidates are removed from the candidate list, and when necessary, zero-valued motion vectors are added to make the candidate list have a fixed length (note that different modes may have different fixed lengths). After constructing the MVP candidate list, the video encoder 20 may select the best motion vector prediction value from the candidate list and encode the corresponding index indicating the selected candidate into the video bitstream.

[0080] In some embodiments, a candidate list (also referred to as a merge candidate list) is constructed by including the following five types of candidates in the following order:

[0081] 1. Spatial MVP (i.e., motion vector prediction value) from spatially neighboring CUs

[0082] 2. Time MVP from the same CU

[0083] 3. History-based MVP from FIFO table

[0084] 4. Average MVP in pairs

[0085] 5. Zero MV

[0086] In some embodiments, the size of the candidate list is signaled in the slice header, and the maximum allowed size of the candidate list is six (e.g., in VVC). For each CU codec in merge mode, the index of the best merge candidate is encoded using truncated unary binarization (TU). The first binary bit of the merge index is coded with context, and bypass codec is used for the other binary bits. In the following context of the present disclosure, this extended merge mode is also referred to as normal merge mode because its concept is the same as the merge mode used in HEVC.

[0087] use Figure 5 As an example and assuming that the candidate list has a fixed length of 2, the motion vector predictor (MVP) candidate list for the current CU may be constructed by performing the following steps in order in AMVP mode:

[0088] 1) Select MVP candidates from spatially adjacent CUs

[0089] a) Get at most one unscaled MVP candidate from one of the two left spatial neighboring CUs starting with A0 and ending with A1;

[0090] b) If no unscaled MVP candidate from the left is available in the previous step, get at most one scaled MVP candidate from one of the two left spatial neighboring CUs starting with A0 and ending with A1;

[0091] c) Get at most one unscaled MVP candidate from one of the three upper spatial neighboring CUs starting with B0, then B1 and ending with B2;

[0092] d) If both A0 and A1 are not available, or if they are coded in intra mode, at most one scaled MVP candidate is obtained from one of the three upper spatial neighboring CUs starting with B0, followed by B1 and ending with B2;

[0093] 2) If two MVP candidates are found in the previous step and they are the same, remove one of the two candidates from the MVP candidate list;

[0094] 3) Select MVP candidates from the temporally co-located CU

[0095] a) If the MVP candidate list after the previous step does not include two MVP candidates, at most one MVP candidate is obtained from the temporally co-located CU (eg, T0);

[0096] 4) Select MVP candidates from the HMVP table

[0097] a) if the MVP candidate list after the previous steps does not include two MVP candidates, obtain at most two history-based MVPs from the HMVP table; and

[0098] 5) If the MVP candidate list after the previous steps does not include two MVP candidates, at most two zero-valued MVPs are added to the MVP candidate list.

[0099] Since there are only two candidates in the AMVP mode MVP candidate list constructed above, an associated semantic element (such as a binary flag) is encoded into the bitstream to indicate which of the two MVP candidates in the candidate list is used to decode the current CU.

[0100] In some embodiments, the MVP candidate list for the current CU in skip or merge mode can be constructed by performing a set of similar steps in the order of the above steps. It should be noted that a special type of merge candidate called "paired merge candidate" is also included in the MVP candidate list for skip or merge mode. Paired merge candidates are generated by averaging the MVs of two previously obtained merge mode motion vector candidates. The size of the merge MVP candidate list (e.g., from 1 to 6) is signaled in the slice header of the current CU. For each CU in merge mode, the index of the best merge candidate is encoded using truncated unary binarization (TU). The first binary bit of the merge index is encoded with context, and for other binary bits, bypass encoding is used.

[0101] As mentioned above, the history-based MVP can be added to the AMVP mode MVP candidate list or the merged MVP candidate list after the spatial MVP and the temporal MVP. The motion information of the previous inter-frame coded CU is stored in the HMVP table and used as the MVP candidate for the current CU. The HMVP table is maintained during the encoding / decoding process. Whenever there is a non-sub-block inter-frame coded CU, (if the HMVP table is full and the same copy of the associated motion vector information does not exist in the table) the associated motion vector information is added to the last entry of the HMVP table as a new candidate, and the motion vector information stored in the first entry of the HMVP table is removed from the HMVP table. Optionally, before adding the associated motion vector information to the last entry of the HMVP table, the same copy of the associated motion vector information is removed from the table.

[0102] As noted above, intra-block copying (IBC) can significantly improve the coding efficiency of screen content material. Since the IBC mode is implemented as a block-level coding mode, block matching (BM) is performed at the video encoder 20 to find the best block vector for each CU. Here, the block vector is used to indicate the displacement from the current block to the reference block that has been reconstructed in the current picture. The IBC mode is considered as a third prediction mode in addition to the intra prediction mode or the inter prediction mode.

[0103] At CU level, the IBC mode may be signaled as IBC AMVP mode or IBC Skip / Merge mode as follows:

[0104] -IBC AMVP mode: The block vector difference (BVD) between the actual block vector of the CU and the block vector prediction value of the CU selected from the block vector candidates of the CU is encoded in the same way as the motion vector difference is encoded in the AMVP mode described above. The block vector prediction method uses two block vector candidates as prediction values, one from the left neighboring block and the other from the upper neighboring block (if IBC encoding). When either neighboring block is not available, the default block vector will be used as the block vector prediction value. A binary flag is transmitted with a signal to indicate the block vector prediction value index. The IBC AMVP candidate list consists of spatial candidates and HMVP candidates.

[0105] - IBC skip / merge mode: The merge candidate index is used to indicate which of the block vector candidates in the merge candidate list (referred to as "merge list" or "candidate list") from the neighboring IBC coded blocks is used to predict the block vector for the current block. The IBC merge candidate list consists of spatial candidates, HMVP candidates, and pairwise candidates.

[0106] FIG. 6A to FIG. 6D is a block diagram illustrating steps for deriving a temporal motion vector predictor (TMVP) of a current block or a sub-block temporal motion vector predictor (SbTMVP) of a sub-block according to some embodiments of the present disclosure.

[0107] In some embodiments, only one temporal motion vector predictor (TMVP) candidate is added to the merge candidate list, such as Figure 5Described. A first flag (sps_temporal_mvp_enabled_flag) is signaled in the sequence parameter set (SPS) of the picture and a second flag (slice_temporal_mvp_enabled_flag) is signaled in the slice header to indicate whether this TMVP candidate is enabled or disabled. Specifically, when deriving a temporal merge candidate, a scaled motion vector is derived from the MV of a co-located picture, which is a previously encoded and decoded picture in a reference picture list. When deriving a temporal motion candidate, an explicit flag (co-located_from_l0_flag) in the slice header is first sent to the decoder to indicate whether the co-located picture is selected from the first reference frame list (list 0) or the second reference frame list (list 1). A co-located reference index (co-located_ref_idx) is further sent to indicate which picture in the list used is selected as the co-located picture for deriving the temporal motion candidate. List 0 (also referred to as L0) and List 1 (also referred to as L1) MVs of temporal motion candidates are independently derived based on the predefined order of MVs of different lists in co-located blocks for co-located pictures according to the following pseudo code:

[0108]

[0109] Table 1: Pseudo code for deriving temporal MV from co-located blocks for TMVP

[0110] like Fig. 6A As shown by the dashed line in , a scaled motion vector 602 for a temporal merge candidate is obtained, where the scaled motion vector 602 is scaled from the motion vector of the selected co-located block using the POC distance tb 604 and the POC distance td 606, where tb is defined as the POC difference between the reference picture of the current picture (e.g., current reference 608) and the current picture (e.g., current picture 610) and td is defined as the POC difference between the reference picture of the co-located picture (e.g., co-located reference 614) and the co-located picture (co-located picture 612). The reference picture index of the temporal merge candidate is set equal to zero. The actual implementation of the scaling process is described in the HEVC specification. For B slices, two motion vectors (one for reference picture list 0 and the other for reference picture list 1) are obtained and combined to form a bi-directional prediction merge candidate.

[0111] like Figure 6B As depicted in , in a co-located block (e.g., co-located block 620) belonging to a reference frame, the position of the temporal candidate is selected between candidates C0 and C1. If the block at position C0 is not available, the block at position C0 is intra-coded, or the block at position C0 is outside the current CTU, position C1 is used. Otherwise, position C0 is used when deriving the temporal merge candidate.

[0112] Some codec standards (e.g., VVC Test Model 1) support a sub-block based temporal motion vector prediction (SbTMVP) approach. Similar to the temporal motion vector prediction (TMVP) in HEVC, SbTMVP uses the motion field in the co-located picture to improve the motion vector prediction and merge mode for the CU in the current picture. The same co-located picture used by TMVP is used for SbTMVP. SbTMVP differs from TMVP in two main aspects:

[0113] 1. TMVP predicts motion at the CU level, while SbTMVP predicts motion at the sub-CU level;

[0114] 2. When TMVP selects a temporal motion vector from a co-located block in a co-located picture (the co-located block is the lower right block or the center block relative to the current CU), SbTMVP applies a motion shift to the temporal motion information selected from the co-located picture, where the motion shift is obtained from the motion vector from one of the spatial neighboring blocks of the current CU.

[0115] FIG. 6C to FIG. 6D The SbTMVP process is shown in FIG. Fig.6D The SbTMVP 632) predicts the current CU in two steps ( Fig.6D In the first step, check the motion vector of a sub-CU (e.g., sub-CU 634) within the current CU 636. Figure 6C A1 (e.g., spatial neighbor 638) in the spatial neighbor. If A1 has a co-located picture (e.g., Fig. 6A 612) as the motion vector of its reference picture, then this motion vector is selected as the motion shift to be applied (e.g., Fig.6D 630). If no such motion vector is identified, the motion shift is set to a zero-valued vector (0,0). The first available motion vector in List 0MV and List 1MV of block A1 is set to the motion shift. In this way, in SbTMVP, the corresponding block can be identified more accurately than in TMVP, where the corresponding block (sometimes referred to as the co-located block) is always in the lower right or center position relative to the current CU. The pseudo code for determining the motion shift is as follows.

[0116]

[0117] Pseudocode for determining motion shift of SbTMVP in VVC

[0118] The variables and functions used in the above table are shown below.

[0119] ColFromL0Flag: Semantics used to indicate whether the co-located picture comes from the list 0 reference picture list

[0120] LDC: used to indicate whether all reference pictures have a smaller POC value than the current picture

[0121] CurrentSliceType: The type of the current slice (picture)

[0122] count: The available number of exported merge candidates

[0123] interDirA1: interDir of the nth merge candidate (1: L0, 2: L1, or 3: Bi)

[0124] refIdxA1[0]: L0 motion information of the Nth merge candidate (e.g. MV, ref.index)

[0125] refIdxA1[1]: L1 motion information of the Nth merge candidate (e.g., MV, ref.index)

[0126] getRefPic(M,I): function used to obtain the reference picture with reference index equal to I from the reference picture list M.

[0127] In the second step, the motion shift identified in step 1 is applied (i.e., the motion shift is added to the coordinates of the current block) to obtain the sub-CU level motion information (motion vector and reference index) from the co-located picture, as Fig.6D shown. Fig.6D The example in assumes that the motion shift is set to the motion of block A1. In actual implementations, the motion shift may be set to any one of the motions of blocks A1, A2, B1 or B2.

[0128] First, a representative sub-CU is selected, and the motion information of the corresponding block of the representative sub-CU is used as the default motion information. In the existing scheme of SbTMVP, the sub-CU located at the lower right of the center position of the current CU is selected as the representative sub-CU. When valid motion information cannot be derived from the corresponding block of the representative sub-CU as the default motion information, the SbTMVP candidate is considered unavailable. When the default motion information is available, proceed to the next step to derive motion information for each sub-CU within the current CU. Whenever no motion information is available for the corresponding block of any sub-CU, the default motion information will be used as the derived temporal motion of that sub-CU.

[0129] Then, for each sub-CU, the motion information of the corresponding block (the minimum motion grid covering the center sample) of the sub-CU in the co-located picture is used to derive the motion information of the sub-CU. After identifying the motion information of the co-located sub-CU, the motion information is converted into the motion vector and reference index of the current sub-CU in a manner similar to the TMVP process of HEVC, where temporal motion scaling is applied to align the reference picture of the temporal motion vector with the reference picture of the current CU.

[0130] It should be noted that in the current design, only the motion field within the co-located CTU in the co-located picture plus one column to the right of the co-located CTU can be used for SbTMVP and TMVP derivation for each CU. Figure 7 As shown in , only the motion information within the co-located CTU plus one column of motion information to the right of the co-located CTU (CTU 2' in this example is the co-located CTU of the current CU) can be used for the temporal MV derivation of SbTMVP and TMVP. In the following, for ease of explanation, we refer to this co-located CTU plus one column as the "valid area" for SbTMVP / TMVP derivation. In this context, whenever the corresponding N×N block in the co-located picture of the sub-CU is outside the valid area, the corresponding N×N block is replaced with an alternative N×N block located in the co-located CTU. The position of the alternative N×N block is derived by cropping the original position of the corresponding N×N block to be within the valid area using the following equation. In the following equation (for the position clipping process of each sub-CU), CurPicWidthInSamplesY and CurPicHeightInSamplesY are the width and height of the codec picture, CTUWidthInSamplesX and CTUWidthInSamplesY are the width and height of the CTU, xCtb and yCtb are the horizontal and vertical positions of the upper left sample of the same CTU. xColCtrCb and yColCtrCb are the horizontal and vertical positions of the representative sample of the sub-CU, MotionShiftX and MotionShiftY are the x and y components of the motion shift, respectively. Functions Clip3(x,y,z) and Min(x,y) are defined as follows.

[0131]

[0132] The position (xColCb, yColCb) of the co-located block in the co-located picture is derived as follows.

[0133]

[0134] In VVC, a combined sub-block based merge list is used to signal a sub-block based merge mode, wherein the combined sub-block based merge list includes both SbTMVP candidates and affine merge candidates. The SbTMVP mode is enabled / disabled by a sequence parameter set (SPS) flag. If the SbTMVP mode is enabled, the SbTMVP prediction value is added as the first entry in the list of sub-block based merge candidates, followed by the affine merge candidates. The size of the sub-block based merge list is signaled in the SPS, and the maximum allowed size of the sub-block based merge list is 5 in VVC.

[0135] The sub-CU size used in SbTMVP is fixed to 8×8, and as done for affine merge mode, SbTMVP mode is only applicable to CUs with both width and height greater than or equal to 8. In addition, in current VVC, for the temporal motion field memory used by TMVP and SbTMVP, motion field compression is performed at 8×8 granularity compared to 16×16 granularity in HEVC.

[0136] In some embodiments, the motion shift is always derived from the list 0MV of the neighboring block; if the list 0MV is not available, the motion shift of the SbTMVP is derived using the list 1MV of the neighboring block. The pseudo code description is as follows:

[0137]

[0138] Pseudocode for determining motion shift of SbTMVP

[0139] In some embodiments, the motion shift is always derived from the list 1MV of the neighboring block; if the list 1MV is not available, the motion shift of the SbTMVP is derived using the list 0MV of the neighboring block. The pseudo code description is as follows:

[0140]

[0141] Pseudocode for determining motion shift of SbTMVP

[0142] In some embodiments, whenever there is any corresponding block of a sub-CU located outside the valid area, a zero vector is used as a motion shift vector to derive the SbTMVP. By doing this, it is guaranteed that the corresponding blocks of all sub-CUs of the current CU are located within the valid area. Therefore, no position clipping process is required for each sub-CU. There are many ways to determine whether there are any corresponding blocks of the sub-CU located outside the valid area in the current CU. In one example, the corresponding block of the upper left N×N sub-CU and the corresponding block of the lower right N×N sub-CU are checked to see if the two corresponding blocks are within the valid area. If either is outside the valid area, a zero vector is used as the motion shift vector; otherwise (both corresponding blocks are within the valid area), the derived motion shift is used for the SbTMVP.

[0143] In some embodiments, SbTMVP is considered unavailable for the current CU whenever there is any corresponding block of the sub-CU that is outside the valid area.

[0144] In some embodiments, whenever there is any corresponding block of a sub-CU located outside the valid area, the motion shift is modified to ensure that the corresponding blocks of all sub-CUs are located within the valid area. Therefore, no position clipping process is required for each sub-CU.

[0145] In some embodiments, a zero vector is always used for SbTMVP derived motion shifts.

[0146] In some embodiments, it is proposed to use a default MV derived from a representative sub-CU as the MV of a sub-CU having a corresponding block located outside the valid area.

[0147] Figure 7A block diagram is shown for determining a valid region for deriving TMVP and SbTMVP for a coding block (e.g., current CU 702) in a current picture (e.g., current picture 704) according to some embodiments of the present disclosure. The valid region is a region in a co-located picture (e.g., co-located picture 704') in which a corresponding CU (e.g., corresponding CU 702') of the current CU (e.g., current CU 702) is being searched for TMVP or SbTMVP. In some embodiments, the valid region is determined by a CTU (e.g., CTU 2') plus a column (e.g., a column of TMV buffer 706) for deriving TMVP and SbTMVP. The valid region constraint is a design for reducing memory usage. By constraining the valid region to be a co-located CTU plus a column, only the motion information within the valid region needs to be stored in an internal memory (e.g., a cache memory) to reduce the average cost (time or energy) of accessing temporal motion data from an external memory. Currently, the maximum CTU size in VVC is 128×128 (the maximum CTU size can be determined later in the VVC profile), and the CTU size can be set to be smaller than 128×128 (for example, 64×64 or 32×32). In one example, when the CTU size is set to 64×64, the valid area is constrained to be the same 64×64 block plus one column. Since the design of the temporal MV buffer for the largest CTU already exists, it may not be wise to use a valid area smaller than the maximum CTU size from a codec efficiency perspective. In some embodiments, the valid area is always fixed to the maximum allowable CTU size plus one column, regardless of the size of the CTU used.

[0148] In some embodiments, the valid region is modified to be only the co-located CTUs.

[0149] According to an embodiment, when the CTU size is equal to the maximum CTU size, the valid area is the same CTU plus one column. When the CTU size is smaller than the maximum CTU size, the valid area is modified to the same CTU plus one column to the right of the same CTU and one row below the same CTU.

[0150] FIG. 8A to FIG. 8B A flowchart illustrating an exemplary process 800 for a video codec to implement a technique for deriving sub-block temporal motion vector prediction values ​​according to some embodiments of the present disclosure is shown. Although the process 800 can be a decoding process or an encoding process, for convenience, the process 800 will be described as being performed by a video decoder (e.g., Figure 3 The decoding process is performed by the video decoder 30).

[0151] As a first step, the decoder determines the co-located picture of the current coding unit (805) (e.g., receiving from the bitstream a first syntax element indicating whether the co-located picture of the current frame is from the first list or the second list; and then receiving from the bitstream a second syntax element indicating which frame in the selected list is used as the co-located frame). For example, referring to Fig. 6A , the current CU 601 in the current picture 610 corresponds to the co-located CU 601 ′ in the co-located picture 612.

[0152] Next, the decoder locates the spatial neighboring blocks of the current coding unit (810). Fig.6D , the current coding unit (eg, current CU 636) has a spatial neighbor 638 (block A1). In some embodiments, the spatial neighbor block is a coding unit or a sub-block.

[0153] After locating the spatial neighboring blocks, the decoder then determines a motion shift vector for the current coding unit (815). The motion shift vector indicates the current picture (e.g., Fig.6D 610 in the current picture) in the current coding unit (eg, Fig.6D ) and the co-located picture (e.g., Fig.6D 612 in the same location) in the corresponding same location block (e.g., Fig.6D The shift of the spatial position between the spatially adjacent blocks 638' (block A1') in.

[0154] In order to determine the motion shift vector, the decoder sequentially checks each motion vector included in the list 0 of the spatial neighboring blocks (820). According to the determination that there is a motion vector in the list 0 that uses the co-located picture as the reference picture of the motion vector (825): the decoder sets the motion vector in the list 0 as the motion shift vector (830) (for example, the motion shift vector 630), and abandons checking the subsequent motion vectors in the list 0 of the spatial neighboring blocks and the motion vectors in the list 1 (835). Therefore, the search for the motion vector is ended, and the first matching motion vector in the list 0 will be used as the motion shift vector. In other words, the decoder always checks the motion vectors included in the list 0 of the spatial neighboring blocks first before checking the list 1 of the spatial neighboring blocks.

[0155] On the other hand, in accordance with determining that there is no motion vector in list 0 that uses the co-located picture as a reference picture (840), the decoder sequentially checks each motion vector included in list 1 of the spatially neighboring block (845). That is, the decoder checks the motion vector of list 1 of the spatially neighboring block if and only if the search for the motion vector in list 0 returns a negative result.

[0156] When searching for motion vectors in list 1 of spatial neighboring blocks, based on determining that there is a motion vector in list 1 that uses a co-located picture as a reference picture for the motion vector (850): the decoder sets the motion vector in list 1 as a motion shift vector (855) and abandons checking subsequent motion vectors in list 1 (860). That is, the first matching motion vector in list 1 will be used as the motion shift vector. Based on determining that there is no motion vector in list 1 that uses a co-located picture as a reference picture for the motion vector (865), the decoder sets the motion shift vector to a zero-valued vector (870). Therefore, the corresponding coding unit and the current coding unit are in the same relative position relative to the co-located picture and the current picture (e.g., there is no motion shift between the current coding unit and the corresponding coding unit).

[0157] Finally, the decoder reconstructs a sub-block-based temporal motion vector of a corresponding sub-block in a plurality of sub-blocks in the current coding unit from a corresponding sub-block in the co-located picture based on the motion shift vector (875). Fig.6D , by scaling (e.g., Fig. 6A and related descriptions) and then uses the motion shift vector 630 to locate the corresponding sub-block temporal motion vector 631 to construct a sub-block temporal motion vector prediction value 632. In some embodiments, the sub-block includes one or two temporal motion vectors from list 0 and list 1.

[0158] In some embodiments, reconstructing a subblock-based temporal motion vector of a corresponding subblock among multiple subblocks in a current coding unit from a corresponding subblock in a co-located picture based on a motion shift vector includes predicting a subblock-based temporal motion vector of a corresponding subblock among multiple subblocks in the current coding unit, including: searching for a co-located subblock corresponding to the corresponding subblock within a predefined area (e.g., a valid area) in the co-located picture based on the motion shift vector; based on determining that the co-located subblock exists within the predefined area in the co-located picture: identifying one or two motion vectors of the co-located subblock; and setting the subblock-based temporal motion vector of the corresponding subblock to: a first picture order count (POC) distance (e.g., a distance between a current picture and a reference picture of the current picture) based on the motion shift vector. Fig. 6A POC distance tb in the co-located picture and a second POC distance between the co-located picture and the reference picture of the co-located picture (eg, Fig. 6A In some embodiments, based on determining that there is no co-located sub-block in the predefined area in the co-located picture, the sub-block-based temporal motion vector of the corresponding sub-block is set to a zero-valued motion vector. In some other embodiments, based on determining that there is no co-located sub-block in the predefined area in the co-located picture, an alternative sub-block in the predefined area in the co-located picture is set to the corresponding sub-block. For example, the alternative sub-block is a boundary sub-block closest to the co-located sub-block in the predefined area.

[0159] In some embodiments, the predefined region has a size equal to the maximum allowable CTU size plus one column, regardless of the size of the CTU that includes the co-located coding unit.

[0160] In some embodiments, the decoder first checks the motion vectors in List 1 of spatially neighboring blocks before checking List 0 of spatially neighboring blocks.

[0161] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted through a computer-readable medium as one or more instructions or codes, and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium such as a data storage medium, or to a communication medium including any medium that facilitates the transfer of a computer program from one place to another (e.g., according to a communication protocol). In this way, a computer-readable medium may generally correspond to (1) a non-transient tangible computer-readable storage medium, or (2) a communication medium, such as a signal or carrier wave. A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the implementation described in the present application. A computer program product may include a computer-readable medium.

[0162] The terms used in the description of the embodiments herein are only used for the purpose of describing specific embodiments and are not intended to limit the scope of the claims. As used in the description of the embodiments and the appended claims, the singular forms "one", "an" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "including" and / or "including ... " when used in this specification, specify the presence of stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or groups thereof.

[0163] It will also be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the embodiment, the first electrode may be referred to as the second electrode, and similarly, the second electrode may be referred to as the first electrode. The first electrode and the second electrode are both electrodes, but they are not the same electrode.

[0164] The description of the present application has been presented for the purpose of illustration and description, and is not intended to be exhaustive or limited to the invention in the disclosed form. With the benefit of the teachings presented in the foregoing description and the associated drawings, many modifications, variations and alternative embodiments will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to best explain the principles of the invention, the practical application, and to enable other persons skilled in the art to understand the various embodiments of the invention, and to best utilize the basic principles and various embodiments with various modifications suitable for the intended specific use. Therefore, it will be understood that the scope of the claims is not limited to the specific examples of the disclosed embodiments, and modifications and other embodiments are intended to be included within the scope of the appended claims.

Claims

1. A method for video encoding, the method comprising: Split the video picture into multiple coding units; Determining a co-located picture of the video picture; Determine a motion shift vector of the current coding unit according to motion vectors of spatially neighboring blocks of the current coding unit, wherein the motion shift vector indicates a shift in spatial position between a subblock of a plurality of subblocks in the current coding unit in the video picture and a corresponding subblock in the co-located picture; reconstructing a subblock-based temporal motion vector of the subblock of the plurality of subblocks in the current coding unit from a corresponding subblock in the co-located picture based on the motion shift vector; The step of determining the motion shift vector of the current coding unit according to the motion vector of a spatially neighboring block of the current coding unit comprises: deriving the motion shift vector from a motion vector associated with a first reference picture list, in case a motion vector of the spatial neighboring block associated with the first reference picture list uses the co-located picture as its reference picture; In the case where the motion vector of the spatial neighboring block associated with the first reference picture list does not use the co-located picture as its reference picture: deriving the motion shift vector from a motion vector associated with a second reference picture list, in a case where a motion vector of the spatial neighboring block associated with the second reference picture list uses the co-located picture as its reference picture; or In a case where the motion vector of the spatial neighboring block associated with the second reference picture list does not use the co-located picture as its reference picture, determining the motion shift vector to be a zero-valued vector; The reconstructing the sub-block-based temporal motion vector of the sub-block of the multiple sub-blocks in the current coding unit from the corresponding sub-block in the co-located picture based on the motion shift vector comprises: Based on the motion shift vector, determine a co-located sub-block corresponding to the sub-block within a predefined area in the co-located picture, wherein, if the position determined according to the motion shift vector is outside the predefined area, clip the position to be within the predefined area to determine the position of the co-located sub-block; and The sub-block based temporal motion vector of the sub-block is set to one or two scaled motion vectors derived based on one or two motion vectors of the co-located sub-block.

2. The method according to claim 1, wherein: The setting the sub-block based temporal motion vector of the sub-block to one or two scaled motion vectors derived based on one or two motion vectors of the co-located sub-block comprises: The sub-block based temporal motion vector of the sub-block is set to: one or two scaled motion vectors derived based on one or two motion vectors of the co-located sub-block, a first picture order count (POC) distance between the video picture and a reference picture of the video picture, and a second POC distance between the co-located picture and a reference picture of the co-located picture.

3. The method of claim 1 , wherein reconstructing the subblock-based temporal motion vector of the subblock of the plurality of subblocks in the current coding unit from the corresponding subblock in the co-located picture based on the motion shift vector comprises: According to determining that the co-located sub-block does not exist in the predefined area in the co-located picture: The sub-block based temporal motion vector of the sub-block is determined to be a zero-valued motion vector.

4. The method of claim 1 , wherein reconstructing the subblock-based temporal motion vector of the subblock of the plurality of subblocks in the current coding unit from the corresponding subblock in the co-located picture based on the motion shift vector comprises: According to determining that the co-located sub-block does not exist in the predefined area in the co-located picture: A replaceable sub-block within the predefined area in the co-located picture is set as the corresponding sub-block, wherein the replaceable sub-block is a boundary sub-block within the predefined area that is closest to the co-located sub-block. The method according to claim 1, wherein the spatial neighboring blocks of the current coding unit are coding units or sub-blocks of coding units.

6. The method of claim 1, wherein the predefined area has a size equal to a maximum allowable CTU size plus one column, and the size of the predefined area is independent of a size of a CTU including the co-located sub-block. The method of claim 6 , wherein the maximum allowable CTU size is 128×128.

8. A computing device comprising: one or more processors; a memory coupled to the one or more processors; as well as A plurality of programs are stored in the memory, and when the plurality of programs are executed by the one or more processors, the computing device performs the method for video encoding as claimed in any one of claims 1 to 7.

9. A non-transitory computer-readable storage medium storing a plurality of programs for execution by a computing device having one or more processors, wherein the plurality of programs, when executed by the one or more processors, causes the computing device to execute a method for video encoding as described in any one of claims 1 to 7 to generate a video bitstream and store the generated video bitstream in the non-transitory computer-readable storage medium.

10. A computer program product comprising computer instructions, characterized in that: When the computer instructions are executed by a processor, the method for video encoding according to any one of claims 1 to 7 is implemented.

11. A method of storing a bitstream, comprising storing the bitstream generated by the method for video encoding according to any one of claims 1 to 7 in a non-transitory computer-readable storage medium.

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