Quantization Parameter-Based Residual Encoder / Decoder Selection and Lower-Layer Signaling

Abstract

The video codec may determine a quantization parameter (QP) value for a block of video data, determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a normal residual codec, and encode a residual of the block of video data using the determined residual codec method.

Description

[0001] This application claims priority to U.S. Application No. 17 / 109,958, filed on December 2, 2020, which claims the benefit of U.S. Provisional Application No. 62 / 944,964, filed on December 6, 2019, and U.S. Provisional Application No. 62 / 953,753, filed on December 26, 2019, the entire contents of each of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to video encoding and video decoding. Background Art

[0003] Digital video capabilities may be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite radio telephones, so-called "smart phones", video teleconferencing devices, video streaming devices, etc. Digital video devices implement video codec techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4 Part 10 Advanced Video Codec (AVC), ITU-T H.265 / High Efficiency Video Codec (HEVC), and extensions of such standards. Digital video devices may more efficiently send, receive, encode, decode, and / or store digital video information by implementing such video codec techniques.

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) may be partitioned into video blocks, which may also be referred to as codec tree units (CTUs), codec units (CUs), and / or codec nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial predictions with respect to reference samples in neighboring blocks within the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial predictions with respect to reference samples in neighboring blocks within the same picture, or temporal predictions with respect to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to as reference frames. Summary of the invention

[0005] In general, the present disclosure describes techniques for determining residual coding processes and related operations in video codecs. In some examples, the present disclosure describes techniques for determining residual coding processes based on quantization parameters (QPs) used in video codecs. The present disclosure also describes techniques for signaling residual coding methods or lossless coding modes based on QP signaling. The techniques of the present disclosure can be applied to both lossy and lossless coding schemes and can be used in any video compression framework or video codec (such as High Efficiency Video Codec (HEVC)), codec tools for currently developing video compression standards (such as Versatile Video Codec (VVC)), and / or other future video codec standards.

[0006] In one example, a method includes: determining a quantization parameter (QP) value for a block of video data; determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and decoding a residual of the block of video data using the determined residual codec method.

[0007] In another example, a device includes: a memory; and one or more processors in communication with the memory, the one or more processors configured to: determine a quantization parameter (QP) value for a block of video data; determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and decode a residual of the block of video data using the determined residual codec method.

[0008] In another example, an apparatus includes: a component for determining a quantization parameter (QP) value for a block of video data; a component for determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and a component for decoding a residual of the block of video data using the determined residual codec method.

[0009] In another example, a computer-readable storage medium is encoded with instructions that, when executed, cause a programmable processor to: determine a quantization parameter (QP) value for a block of video data; determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and decode a residual of the block of video data using the determined residual codec method.

[0010] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0012] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and a corresponding codec tree unit (CTU).

[0013] Figure 3 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0014] Figure 4 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0015] Figure 5 is a flow chart illustrating an example encoding method of the present disclosure.

[0016] Figure 6 is a flow chart illustrating an example decoding method of the present disclosure.

[0017] Figure 7 is a flowchart illustrating another example decoding method of the present disclosure. DETAILED DESCRIPTION

[0018] In some example video codecs, different residual coding methods are used. For example, the video codec can be configured to use transform skip (TS) residual coding to code blocks of residual video data. In TS residual coding, the video codec is configured not to transform the residual blocks using an implicitly or explicitly determined transform (e.g., discrete cosine transform (DCT-2)). That is, the video codec does not perform a transform on the residual blocks. Without using TS residual coding, the video codec can be configured to use different residual coding methods, which are referred to as regular residual coding (RRC) or transform residual coding.

[0019] In some examples, the video codec is configured to determine the use of TS residual codec or conventional residual codec based on whether to skip transforms and / or use block differential pulse codec modulation (BDPCM) before or after residual codec. The present disclosure describes a variety of techniques for determining a residual codec method based on a quantization parameter (QP) value. In some examples, the video encoder 200 and / or the video decoder 300 may be configured to use the QP value alone when determining the residual codec method to be used. In other examples, the video encoder 200 and / or the video decoder 300 may be configured to use the QP value in combination with other codec information (such as a flag) to determine the residual codec method. The techniques of the present disclosure can increase codec efficiency and / or reduce the overhead of singulation for indicating the residual codec method.

[0020] Figure 1 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of the present disclosure. The techniques of the present disclosure are generally directed to encoding and decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Therefore, video data may include original unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata such as signaling data.

[0021] like Figure 1 As shown, in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116. Specifically, source device 102 provides the video data to destination device 116 via computer-readable medium 110. Source device 102 and destination device 116 may include any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, mobile devices, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication, and thus may be referred to as wireless communication devices.

[0022] exist Figure 1In the example of , source device 102 includes video source 104, memory 106, video encoder 200 and output interface 108. Destination device 116 includes input interface 122, video decoder 300, memory 120 and display device 118. According to the present disclosure, video decoder 200 of source device 102 and video decoder 300 of destination device 116 can be configured to apply a technique for determining a residual encoding and decoding process. Therefore, source device 102 represents an example of a video encoding device, and destination device 116 represents an example of a video decoding device. In other examples, source device and destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source such as an external camera. Similarly, destination device 116 may interface with an external display device instead of including an integrated display device.

[0023] like Figure 1 The system 100 shown is only an example. In general, any digital video encoding and / or decoding device can perform the technology for determining the residual encoding and decoding process. The source device 102 and the destination device 116 are only examples of such a codec device, wherein the source device 102 generates coded video data to send to the destination device 116. The present disclosure refers to a "codec" device as a device that performs the encoding and decoding (encoding and / or encoding) of data. Therefore, the video encoder 200 and the video decoder 300 represent examples of codec devices, specifically, examples of video encoders and video decoders, respectively. In some examples, the source device 102 and the destination device 116 can operate in a substantially symmetrical manner, so that each of the source device 102 and the destination device 116 includes a video encoding and decoding component. Therefore, the system 100 can support one-way or two-way video transmission between the source device 102 and the destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0024] Typically, the video source 104 represents a source of video data (i.e., original, unencoded video data), and provides a continuous sequence of pictures (also referred to as "frames") of the video data to the video encoder 200, which encodes the data of the pictures. The video source 104 of the source device 102 may include a video capture device such as a camera, a video archive containing previously captured original video, and / or a video feed interface receiving video from a video content provider. As another alternative, the video source 104 may generate computer graphics-based data as the source video, or a combination of real-time video, archived video, and computer-generated video. In each case, the video encoder 200 encodes the captured, pre-captured, or computer-generated video data. The video encoder 200 may rearrange the pictures from the received order (sometimes referred to as "display order") to a codec order for encoding and decoding. The video encoder 200 may generate a bitstream comprising encoded video data. Source device 102 may then output the encoded video data onto computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of destination device 116 .

[0025] The memory 106 of the source device 102 and the memory 120 of the destination device 116 represent general purpose memories. In some examples, the memories 106, 120 can store original video data, for example, original video from the video source 104 and original decoded video data from the video decoder 300. Additionally or alternatively, the memories 106, 120 can store software instructions that can be executed by the video encoder 200 and the video decoder 300, respectively, for example. Although the memory 106 and the memory 120 are shown separately from the video encoder 200 and the video decoder 300 in this example, it should be understood that the video encoder 200 and the video decoder 300 can also include internal memory to achieve functionally similar or equivalent purposes. In addition, the memories 106, 120 can store, for example, encoded video data output from the video encoder 200 and input to the video decoder 300. In some examples, portions of the memories 106, 120 can be allocated as one or more video buffers, for example, to store original, decoded and / or encoded video data.

[0026] The computer-readable medium 110 may represent any type of medium or device capable of transmitting the encoded video data from the source device 102 to the destination device 116. In one example, the computer-readable medium 110 represents a communication medium for enabling the source device 102 to transmit the encoded video data directly to the destination device 116 in real time, for example, via a radio frequency network or a computer-based network. According to a communication standard such as a wireless communication protocol, the output interface 108 may modulate the transmission signal including the encoded video data, and the input interface 122 may demodulate the received transmission signal. 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 part of a packet-based network such as 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 facilitates communication from the source device 102 to the destination device 116.

[0027] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media for storing encoded video data, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium.

[0028] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device that may store the encoded video data generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or downloading.

[0029] The file server 114 may be any type of server device capable of storing encoded video data and sending the encoded video data to the destination device 116. The file server 114 may represent a network server (e.g., for a website), a server configured to provide a file transfer protocol service (e.g., a file transfer protocol (FTP) or a file delivery over unidirectional transport (FLUTE) protocol), a content delivery network (CDN) device, a hypertext transfer protocol (HTTP) server, a multimedia broadcast multicast service (MBMS) or an enhanced MBMS (eMBMS) server, and / or a network attached storage (NAS) device. Additionally or alternatively, the file server 114 may implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Live Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, etc.

[0030] Destination device 116 may access the encoded video data from file server 114 through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.), or a combination of both, suitable for accessing the encoded video data stored on file server 114. Input interface 122 may be configured to operate according to any one or more of the various protocols discussed above for retrieving or receiving media data from file server 114, or other such protocols for retrieving media data.

[0031] Output interface 108 and input interface 122 may represent wireless transmitters / receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of the various IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless components, output interface 108 and input interface 122 may be configured to transmit data such as encoded video data according to a cellular communication standard such as 4G, 4G-LTE (Long Term Evolution), LTE Advanced, 5G, etc. In some examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 may be configured to transmit data such as encoded video data according to other wireless standards such as IEEE 802.11 specifications, IEEE 802.15 specifications (e.g., ZigBee TM ),Bluetooth TMIn some examples, source device 102 and / or destination device 116 may include respective system-on-chip (SoC) devices. For example, source device 102 may include a SoC device for performing functions attributed to video encoder 200 and / or output interface 108, and destination device 116 may include a SoC device for performing functions attributed to video decoder 300 and / or input interface 122.

[0032] The techniques of the present disclosure can be applied to video encoding and decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission (such as Dynamic Adaptive Streaming over HTTP (DASH)), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0033] The input interface 122 of the destination device 116 receives an encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 and also used by the video decoder 300, such as syntax elements with values ​​describing characteristics and / or processing of video blocks or other coded units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent 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.

[0034] Despite Figure 1 2, but in some examples, the video encoder 200 and the video decoder 300 may each be integrated with an audio encoder and / or an audio decoder and may include appropriate MUX-DEMUX units or other hardware and / or software to process a multiplexed stream including both audio and video in a common data stream. If applicable, the MUX-DEMUX unit may conform to the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

[0035] The video encoder 200 and the video decoder 300 can each be implemented as any of a variety of suitable encoder and / or decoder 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 the technology is partially implemented in software, the device may store instructions for the software in a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the technology of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, any of which can be integrated as part of a combined encoder / decoder (CODEC) in a corresponding device. A device including the video encoder 200 and / or the video decoder 300 may include an integrated circuit, a microprocessor, and / or a wireless communication device (such as a cellular phone).

[0036] The video encoder 200 and the video decoder 300 may operate according to a video codec standard such as ITU-T H.265 (also known as High Efficiency Video Codec (HEVC)) or an extension thereof (such as a multi-view and / or scalable video codec extension). Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary or industry standards such as the Joint Exploration Test Model (JEM) or ITU-T H.266 (also known as the Versatile Video Codec (VVC)). A recent draft of the VVC standard is described in Bross et al., “Versatile Video Coding (Draft 7)”, ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 16th Meeting: Geneva, Switzerland, October 1-11, 2019, JVET-S2001-v9 (hereinafter referred to as “VVC Draft 7”). However, the technology of the present disclosure is not limited to any specific codec standard.

[0037] Typically, the video encoder 200 and the video decoder 300 can perform block-based picture encoding and decoding. The term "block" generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. Typically, the video encoder 200 and the video decoder 300 can encode and decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, the video encoder 200 and the video decoder 300 can encode and decode luminance and chrominance components instead of encoding and decoding red, green, and blue (RGB) data of samples of a picture, wherein the chrominance component may include both a red hue chrominance component and a blue hue chrominance component. In some examples, the video encoder 200 converts the received RGB format data into a YUV representation before encoding, and the video decoder 300 converts the YUV representation into an RGB format. Alternatively, a pre-processing and post-processing unit (not shown) can perform these conversions.

[0038] The present disclosure may generally relate to the encoding and decoding of a picture (e.g., encoding and decoding) to include the process of encoding or decoding the data of the picture. Similarly, the present disclosure may relate to the encoding and decoding of a block of a picture to include the process of encoding or decoding the data of the block, for example, prediction and / or residual encoding and decoding. The encoded video bitstream generally includes a series of values ​​of syntax elements for representing codec decisions (e.g., codec mode) and partitioning of the picture into blocks. Therefore, references to encoding and decoding a picture or a block should generally be understood as encoding and decoding the values ​​of the syntax elements that form the picture or block.

[0039] HEVC defines various blocks, including codec units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video codec (e.g., video encoder 200) partitions a codec tree unit (CTU) into CUs according to a quadtree structure. That is, the video encoder partitions the CTU and CU into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without child nodes may be referred to as a "leaf node", and the CU of such a leaf node may include one or more PUs and / or one or more TUs. The video codec may further partition the PU and TU. For example, in HEVC, a residual quadtree (RQT) represents the partitioning of a TU. In HEVC, a PU represents inter-frame prediction data, and a TU represents residual data. An intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0040] As another example, the video encoder 200 and the video decoder 300 may be configured to operate according to VVC. According to VVC, a video codec (e.g., the video encoder 200) partitions a picture into a plurality of codec tree units (CTUs). The video encoder 200 may partition the CTU according to a tree structure such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure removes the concept of multiple partition types, such as the separation between CU, PU, ​​and TU of HEVC. The QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of the binary tree correspond to codec units (CUs).

[0041] In the MTT partitioning structure, blocks can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) partitioning. Ternary tree partitioning is a partitioning that splits a block into three sub-blocks. In some examples, ternary tree partitioning divides a block into three sub-blocks without dividing the initial block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0042] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma and chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for corresponding chroma components).

[0043] The video encoder 200 and the video decoder 300 may be configured to use per-HEVC quadtree segmentation, QTBT segmentation, MTT segmentation, or other segmentation structures. For purposes of explanation, the description of the disclosed technology is presented with respect to QTBT segmentation. However, it should be understood that the disclosed technology may also be applied to a video codec configured to use quadtree segmentation or other types of segmentation.

[0044] In some examples, a CTU includes a codec tree block (CTB) of luma samples, two corresponding CTBs of chroma samples of a picture with three sample arrays, or a CTB of samples of a monochrome picture or a picture encoded and decoded using three independent color planes and syntax structures for codec samples. A CTB can be an NxN block of samples for some N value, so that the division of components into each CTB is a partitioning. A component is an array or a single sample of one of the three arrays (luminance and two chroma) that make up a picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of an array that makes up a picture in monochrome format. In some examples, a codec block is an MxN block of samples for some M and N values, so that the division of a CTB into codec blocks is a partitioning.

[0045] Blocks (e.g., CTUs or CUs) can be grouped in various ways in a picture. As an example, a brick can refer to a rectangular area of ​​a CTU row within a particular tile in a picture. A tile can be a rectangular area of ​​a CTU within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular area of ​​a CTU having a height equal to the picture height and a width specified by a syntax element (e.g., such as in a picture parameter set). A tile row refers to a rectangular area of ​​a CTU having a height specified by a syntax element (e.g., such as in a picture parameter set) and a width equal to the picture width.

[0046] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not partitioned into multiple bricks may also be referred to as a brick. However, a brick that is a proper subset of a tile may not be referred to as a tile.

[0047] Tiles in a picture can also be arranged into slices. A slice can be an integer number of tiles of a picture that can be contained exclusively in a single network abstraction layer (NAL) unit. In some examples, a slice includes a contiguous sequence of multiple complete tiles or just complete tiles of one tile.

[0048] This disclosure may use "NxN" and "N times N" interchangeably to refer to the sample dimensions of a block (e.g., a CU or other video block) in terms of vertical and horizontal dimensions, such as 16x16 samples or 16 times 16 samples. Typically, a 16x16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an NxN CU typically has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. The samples in a CU may be arranged in rows and columns. In addition, a CU does not necessarily have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0049] The video encoder 200 encodes video data for a CU representing prediction and / or residual information and other information. The prediction information indicates how the CU is to be predicted in order to form a prediction block for the CU. The residual information typically represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0050] In order to predict a CU, the video encoder 200 can generally form a prediction block of the CU by inter-frame prediction or intra-frame prediction. Inter-frame prediction generally refers to predicting a CU from data of a previously coded picture, while intra-frame prediction generally refers to predicting a CU from previously coded data of the same picture. In order to perform inter-frame prediction, the video encoder 200 can use one or more motion vectors to generate a prediction block. The video encoder 200 can generally perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and the reference block. The video encoder 200 can calculate a difference metric using the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean square difference (MSD), or other such difference calculations to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 can use unidirectional prediction or bidirectional prediction to predict the current CU.

[0051] Some examples of VVC also provide an affine motion compensation mode, which can be considered an inter-frame prediction mode. In the affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion (e.g., zooming in or out, rotation, perspective motion, or other irregular motion types).

[0052] To perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. Some examples of VVC provide sixty-seven intra prediction modes, including various directional modes as well as planar and DC modes. Typically, the video encoder 200 selects an intra prediction mode that describes neighboring samples to a current block (e.g., a block of a CU) to predict samples of the current block from. Assuming that the video encoder 200 encodes and decodes CTUs and CUs in a raster scan order (from left to right, from top to bottom), such samples can typically be above, above left, or to the left of the current block in the same picture as the current block.

[0053] The video encoder 200 encodes data representing the prediction mode for the current block. For example, for inter-frame prediction mode, the video encoder 200 can encode data indicating which of the various available inter-frame prediction modes is used and motion information for the corresponding mode. For example, for unidirectional or bidirectional inter-frame prediction, the video encoder 200 can encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. The video encoder 200 can use a similar mode to encode motion vectors for affine motion compensation mode.

[0054] After a prediction such as intra prediction or inter prediction of a block, the video encoder 200 may calculate residual data for the block. The residual data (e.g., a residual block) represents the sample-by-sample difference between the block and a prediction block of the block formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to generate transformed data in a transform domain rather than a sample domain. For example, the video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Additionally, the video encoder 200 may apply a secondary transform after a primary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 generates transform coefficients after applying one or more transforms.

[0055] As described above, after any transform used to generate transform coefficients, the video encoder 200 can perform quantization of the transform coefficients. Quantization generally refers to the process of quantizing the transform coefficients to possibly reduce the amount of data used to represent the coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all coefficients. For example, the video encoder 200 can round down an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 can perform a bitwise right shift on the value to be quantized.

[0056] After quantization, the video encoder 200 may scan the transform coefficients to generate a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place coefficients of higher energy (and therefore lower frequency) at the front of the vector and transform coefficients of lower energy (and therefore higher frequency) at the back of the vector. In some examples, the video encoder 200 may scan the quantized transform coefficients using a predefined scan order to generate a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 may perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 may entropy encode the one-dimensional vector, for example, according to context adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy encode the value of a syntax element that describes metadata associated with the encoded video data for use by the video decoder 300 when decoding the video data.

[0057] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be sent. The context may relate to, for example, whether neighboring values ​​of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0058] The video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, to the video decoder 300, such as in a picture header, a block header, a slice header, or other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). The video decoder 300 may similarly decode such syntax data to determine how to decode the corresponding video data.

[0059] In this way, the video encoder 200 can generate a bitstream that includes coded video data, such as a syntax element describing the partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual information of the blocks. Finally, the video decoder 300 can receive the bitstream and decode the coded video data.

[0060] In general, the video decoder 300 performs a process that is the reverse of the process performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 may decode the values ​​of the syntax elements of the bitstream using CABAC in a manner substantially similar to (although reversed from) the CABAC encoding process of the video encoder 200. The syntax elements may define partitioning information for partitioning a picture into CTUs, and partitioning each CTU according to a corresponding partitioning structure such as a QTBT structure to define CUs of the CTU. The syntax elements may further define prediction and residual information for a block (e.g., CU) of video data.

[0061] The residual information may be represented by, for example, quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce a residual block for the block. The video decoder 300 uses the prediction mode (intra-frame or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) sent by signaling to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along the boundaries of the blocks.

[0062] According to the technology of the present disclosure, the video encoder 200 and the video decoder 300 can be configured to determine a quantization parameter (QP) value for a block of video data; determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and encode and decode the residual of the block of video data using the determined residual codec method.

[0063] The present disclosure may generally involve "signaling" certain information, such as syntax elements. The term "signaling" may generally involve the transmission of values ​​for syntax elements and / or other data used to decode encoded video data. That is, the video encoder 200 may signal values ​​for syntax elements in a bitstream. Typically, signaling involves generating values ​​in a bitstream. As mentioned above, the source device 102 may transmit the bitstream to the destination device 116 substantially in real time or in non-real time, such as may occur when storing syntax elements to the storage device 112 for later retrieval by the destination device 116.

[0064] Figure 2A and Figure 2Bis a conceptual diagram showing an example quadtree binary tree (QTBT) structure 130 and a corresponding codec tree unit (CTU) 132. Solid lines represent quadtree splits, and dashed lines indicate binary tree splits. In each split (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which split type (i.e., horizontal or vertical) is used, where in this example, 0 indicates a horizontal split and 1 indicates a vertical split. For a quadtree split, there is no need to indicate the split type because the quadtree node splits the block horizontally and vertically into 4 equally sized sub-blocks. Thus, the video encoder 200 can encode, and the video decoder 300 can decode, syntax elements (such as split information) for the region tree level (i.e., solid lines) of the QTBT structure 130 and syntax elements (such as split information) for the prediction tree level (i.e., dashed lines) of the QTBT structure 130. The video encoder 200 may encode, and the video decoder 300 may decode, video data (such as prediction and transform data) of the CU represented by the terminal leaf node of the QTBT structure 130 .

[0065] generally, Figure 2B The CTU 132 may be associated with parameters defining the size of blocks corresponding to nodes of the QTBT structure 130 at the first level and the second level. These parameters may include a CTU size (indicating the size of the CTU 132 in samples), a minimum quadtree size (MinQTSize, indicating the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, indicating the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, indicating the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, indicating the minimum allowed binary tree leaf node size).

[0066] The root node of the QTBT structure corresponding to the CTU may have four child nodes at the first level of the QTBT structure, each of which may be segmented according to a quadtree segmentation. That is, the node at the first level is a leaf node (without child nodes) or has four child nodes. The example of the QTBT structure 130 represents such a node as including a parent node and a child node with a solid line branch. If the nodes at the first level are not larger than the maximum allowed binary tree root node size (MaxBTSize), they may be further segmented by their respective binary trees. The binary tree splitting of a node may be iterated until the node generated by the split reaches the minimum allowed binary tree leaf node size (MinBTSize) or the maximum allowed binary tree depth (MaxBTDepth). The example of the QTBT structure 130 represents such a node as having a dotted line branch. The binary tree leaf node is referred to as a codec unit (CU), which is used for prediction (e.g., intra-picture or inter-picture prediction) and transformation without any further segmentation. As discussed above, a CU may also be referred to as a "video block" or "block".

[0067] In one example of a QTBT partitioning structure, the CTU size is set to 128x128 (luminance sample and two corresponding 64x64 chrominance samples), MinQTSize is set to 16x16, MaxBTSize is set to 64x64, MinBTSize (for both width and height) is set to 4, and MaxBTDepth is set to 4. Quadtree partitioning is first applied to the CTU to generate a quadtree leaf node. The quadtree leaf node can have a size from 16x16 (i.e., MinQTSize) to 128x128 (i.e., CTU size). If the quadtree leaf node is 128x128, it will not be further split by the binary tree because the size exceeds MaxBTSize (i.e., 64x64 in this example). Otherwise, the quadtree leaf node will be further split by the binary tree. Therefore, the quadtree leaf node is also the root node of the binary tree and has a binary tree depth of 0. When the binary tree depth reaches MaxBTDepth (4 in this example), further splitting is not allowed. When a binary tree node has a width equal to MinBTSize (4 in this example), it means that no further vertical splitting is allowed. Similarly, a binary tree node with a height equal to MinBTSize means that no further horizontal splitting is allowed for the binary tree node. As described above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further segmentation.

[0068] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3The above description is provided for the purpose of explanation and should not be considered as limiting the techniques as broadly illustrated and described in this disclosure. For the purpose of explanation, this disclosure describes the video encoder 200 in the context of video codec standards such as the HEVC video codec standard and the developing H.266 (VVC) video codec standard. However, the techniques of this disclosure are not limited to these video codec standards and are generally applicable to video encoding and decoding.

[0069] exist Figure 3 In the example of the video encoder 200, a video data memory 230, a mode selection unit 202, a residual generation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a filter unit 216, a decoded picture buffer (DPB) 218, and an entropy coding unit 220 are included. Any or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or processing circuits. For example, the units of the video encoder 200 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. In addition, the video encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.

[0070] Video data memory 230 may store video data to be encoded by components of video encoder 200. Video encoder 200 may receive video data from, for example, video source 104 ( Figure 1 ) receives video data stored in video data memory 230. DPB218 can be used as a reference picture memory for storing reference video data for use by video encoder 200 to predict subsequent video data. Video data memory 230 and DPB218 can 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. Video data memory 230 and DPB 218 can be provided by the same memory device or a separate memory device. In various examples, video data memory 230 can be on the chip with other components of the video encoder 200 as shown, or off the chip relative to those components.

[0071] In the present disclosure, references to the video data memory 230 should not be interpreted as limited to memory internal to the video encoder 200 (unless explicitly described as such) or memory external to the video encoder 200 (unless explicitly described as such). Rather, references to the video data memory 230 should be understood as a reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data for a current block to be encoded). Figure 1 The memory 106 may also provide temporary storage of outputs from the various units of the video encoder 200 .

[0072] Show Figure 3 Various units are provided to help understand the operations performed by the video encoder 200. These units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide specific functionality and are preset on executable operations. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the operations that can be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more of these units may be different circuit blocks (fixed-function or programmable), and in some examples, one or more of these units may be integrated circuits.

[0073] The video encoder 200 may include an arithmetic logic unit (ALU), an elementary function unit (EFU), a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video encoder 200 is performed using software executed by a programmable circuit, the memory 106 ( Figure 1 ) may store instructions (eg, object code) for software received and executed by the video encoder 200, or another memory (not shown) within the video encoder 200 may store such instructions.

[0074] The video data memory 230 is configured to store the received video data. The video encoder 200 may retrieve the picture of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 may be the original video data to be encoded.

[0075] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units to perform video prediction according to other prediction modes. As an example, the mode selection unit 202 may include a palette unit, an intra-block copy unit (which may be part of the motion estimation unit 222 and / or the motion compensation unit 224), an affine unit, a linear model (LM) unit, etc.

[0076] The mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values ​​for such combinations. The encoding parameters may include partitioning of a CTU into CUs, a prediction mode for a CU, a transform type for residual data of a CU, a quantization parameter for residual data of a CU, etc. The mode selection unit 202 may ultimately select a combination of encoding parameters that has a better rate-distortion value than other tested combinations.

[0077] The video encoder 200 may partition the picture retrieved from the video data memory 230 into a series of CTUs, and encapsulate one or more CTUs into a slice. The mode selection unit 202 may partition the CTUs of the picture according to a tree structure (e.g., the QTBT structure or quadtree structure of HEVC described above). As described above, the video encoder 200 may form one or more CUs by partitioning the CTUs according to the tree structure. The CU may also be generally referred to as a "video block" or "block".

[0078] Typically, the mode selection unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a prediction block for the current block (e.g., the current CU, or in HEVC, the overlapping portion of the PU and TU). For inter prediction of the current block, the motion estimation unit 222 can perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in the DPB 218). In particular, the motion estimation unit 222 can calculate values ​​representing how similar the potential reference blocks are to the current block, for example, based on the sum of absolute differences (SAD), the sum of squared differences (SSD), the mean absolute difference (MAD), the mean squared difference (MSD), etc. The motion estimation unit 222 can generally perform these calculations using the sample-by-sample differences between the current block under consideration and the reference block. The motion estimation unit 222 can identify the reference block with the lowest value resulting from these calculations, thereby indicating the reference block that most closely matches the current block.

[0079] The motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in a current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, for unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then use the motion vectors to generate a prediction block. For example, the motion compensation unit 224 may use the motion vectors to retrieve data for the reference block. As another example, if the motion vectors have fractional sample precision, the motion compensation unit 224 may interpolate values ​​for the prediction block according to one or more interpolation filters. In addition, for bidirectional inter prediction, the motion compensation unit 224 may retrieve data for two reference blocks identified by the corresponding motion vectors and combine the retrieved data, for example, by sample-by-sample averaging or weighted averaging.

[0080] As another example, for intra prediction or intra prediction codec, the intra prediction unit 226 can generate a prediction block from samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 can generally mathematically combine the values ​​of adjacent samples and pad these calculated values ​​in a defined direction across the current block to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average of samples adjacent to the current block and generate a prediction block to include the resulting average for each sample of the prediction block.

[0081] The mode selection unit 202 provides the prediction block to the residual generation unit 204. The residual generation unit 204 receives the original uncoded version of the current block from the video data memory 230 and receives the prediction block from the mode selection unit 202. The residual generation unit 204 calculates the sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, the residual generation unit 204 may also determine the difference between the sample values ​​in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, the residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0082] In the example where the mode selection unit 202 partitions the CU into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. The video encoder 200 and the video decoder 300 may support PUs of various sizes. As described above, the size of the CU may refer to the size of the luma codec block of the CU, and the size of the PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2Nx2N, the video encoder 200 may support PU sizes of 2Nx2N or NxN for intra-prediction, and support symmetric PU sizes of 2Nx2N, 2NxN, Nx2N, NxN or the like for inter-prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning of PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter-prediction.

[0083] In an example where the mode selection unit 202 does not further partition the CU into PUs, each CU may be associated with a luma codec block and a corresponding chroma codec block. As described above, the size of a CU may refer to the size of the luma codec block of the CU. The video encoder 200 and the video decoder 300 may support a CU size of 2Nx2N, 2NxN, or Nx2N.

[0084] For other video coding techniques such as intra-block copy mode coding, affine mode coding, and linear model (LM) mode coding, as some examples, the mode selection unit 202 generates a prediction block for the current block being encoded via a corresponding unit associated with the coding technique. In some examples such as palette mode coding, the mode selection unit 202 may not generate a prediction block, but instead generate syntax elements indicating how to reconstruct the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 for encoding.

[0085] As described above, the residual generation unit 204 receives video data for a current block and a corresponding prediction block. The residual generation unit 204 then generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates the sample-by-sample difference between the prediction block and the current block.

[0086] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 can apply various transforms to the residual block to form a transform coefficient block. For example, the transform processing unit 206 can apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 can perform multiple transforms on the residual block, such as a primary transform and a secondary transform such as a rotation transform. In some examples, the transform processing unit 206 does not apply a transform to the residual block.

[0087] Quantization unit 208 may quantize transform coefficients in a transform coefficient block to produce a quantized transform coefficient block. Quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. Video encoder 200 may adjust the degree of quantization applied to the coefficient block associated with the current block (e.g., via mode selection unit 202) by adjusting the QP value associated with the CU. Quantization may introduce information loss, and therefore, the quantized transform coefficients may have lower precision than the original transform coefficients produced by transform processing unit 206.

[0088] QP adjusts the amount of spatial detail retained. If a relatively small QP value is used, more information is saved at the expense of a reduced bit rate. Similarly, a relatively large QP value increases quantization and generally results in a higher bit rate. However, greater quantization via larger QP values ​​also reduces the visual statistical quality of the compressed image. Therefore, the video encoder 200 can be configured to determine the QP value so that there is a trade-off between visual quality and bit rate. The video encoder 200 can be configured to signal the determined QP value to the video decoder 300, or the video decoder 300 can be configured to predict the determined QP value from previous frames and other statistics within the compression framework.

[0089] VVC Draft 7 specifies two different residual coding methods. In one example, the video encoder 200 is configured to encode and decode blocks of residual video data using transform skip (TS) residual coding. In TS residual coding, the video encoder 200 is configured not to transform the residual blocks using an implicit or explicit transform, such as discrete cosine transform (DCT-2). That is, the video encoder 200 does not perform a transform on the residual blocks. Therefore, the residual is encoded and decoded in the spatial domain.

[0090] For example, refer to Figure 3, the operations of the transform processing unit 206 and the inverse transform processing unit 212 can be skipped. In one example, the video encoder 200 can use a transform skip flag to signal the use of TS residual codec. For example, the syntax element transform_skip_flag[x0][y0][cIdx] specifies whether the transform is applied to the associated transform block (e.g., the residual block). A value of 0 indicates that the transform can be skipped in some cases (e.g., the transform skip is based on other syntax elements). A value of 1 indicates that the transform process is skipped.

[0091] In the case where TS residual codec is not used, the video encoder 200 can be configured to use a different residual codec method, which is called regular residual codec (RRC) or transform residual codec. Figure 3 When performing conventional residual coding, the operations of the transform processing unit 206 and the inverse transform processing unit 212 are performed as described above and in further detail below.

[0092] In some examples, such as in VVC draft 7, the video encoder 200 is configured to determine the use of TS residual codec or conventional residual codec based on whether the transform is skipped before the residual and / or whether block differential pulse code modulation (BDPCM) is used. Both TS residual codec and conventional residual codec can be used for the luminance and chrominance components of the video codec block.

[0093] As will be described in more detail below, the present disclosure describes a variety of techniques for determining a residual codec method based on a QP value. For example, the video encoder 200 can be configured to determine a quantization parameter (QP) value for a block of video data, determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec, and encode a residual of the block of video data using the determined residual codec method. The techniques of the present disclosure can increase codec efficiency and / or reduce a singularization overhead for indicating a residual codec method.

[0094] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform to the quantized transform coefficient block, respectively, to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (although possibly with some degree of distortion) based on the reconstructed residual block and the prediction value block generated by the mode selection unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples of the prediction value block generated by the mode selection unit 202 to generate a reconstructed block.

[0095] Filter unit 216 may perform one or more filter operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edge of the CU. In some examples, the operations of filter unit 216 may be skipped.

[0096] The video encoder 200 stores the reconstructed blocks in the DPB 218. For example, in examples where the operation of the filter unit 216 is not required, the reconstruction unit 214 can store the reconstructed blocks in the DPB 218. In examples where the operation of the filter unit 216 is required, the filter unit 216 can store the filtered reconstructed blocks in the DPB 218. The motion evaluation unit 222 and the motion compensation unit 224 can retrieve a reference picture formed by the reconstructed (and possibly filtered) blocks from the DPB 218 to perform inter-frame prediction on blocks of subsequent coded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed blocks in the DPB 218 of the current picture to perform intra-frame prediction on other blocks in the current picture.

[0097] In general, the entropy coding unit 220 may entropy encode syntax elements received from other functional components of the video encoder 200. For example, the entropy coding unit 220 may entropy encode a quantized transform coefficient block from the quantization unit 208. As another example, the entropy coding unit 220 may entropy encode a prediction syntax element (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from the mode selection unit 202. The entropy coding unit 220 may perform one or more entropy coding operations on syntax elements as another example of video data to generate entropy-encoded data. For example, the entropy coding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable to variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a probability interval partitioning entropy (PIPE) coding operation, an exponential Golomb coding operation, or another type of entropy coding operation on the data. In some examples, the entropy coding unit 220 may operate in a bypass mode in which the syntax elements are not entropy encoded.

[0098] The video encoder 200 may output a bitstream containing entropy-coded syntax elements required to reconstruct a slice block or a picture block. Specifically, the entropy coding unit 220 may output a bitstream.

[0099] The operations described above are for block descriptions. Such descriptions should be understood as operations for luma codec blocks and / or chroma codec blocks. As described above, in some examples, the luma codec block and the chroma codec block are the luma and chroma components of a CU. In some examples, the luma codec block and the chroma codec block are the luma and chroma components of a PU.

[0100] In some examples, the operations performed for the luma codec block do not need to be repeated for the chroma codec block. As an example, the operations for identifying the motion vector (MV) and reference picture of the luma codec block do not need to be repeated in order to identify the MV and reference picture of the chroma block. Instead, the MV of the luma codec block can be scaled to determine the MV of the chroma block, and the reference picture can be the same. As another example, the intra prediction process can be the same for the luma codec block and the chroma codec block.

[0101] The video encoder 200 represents an example of a device configured to encode video data, the device including a memory configured to store the video data, and one or more processing units implemented in a circuit and configured to determine a quantization parameter (QP) value for a block of the video data; determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and encode a residual of the block of the video data using the determined residual codec method.

[0102] Figure 4 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 4 It is provided for the purpose of explanation and should not be considered as limiting the techniques as widely illustrated and described in this disclosure. For the purpose of explanation, this disclosure describes the video decoder 300 according to the techniques of JEM, VVC and HEVC. However, the techniques of this disclosure can be performed by video codec devices configured for other video codec standards.

[0103] exist Figure 4 In the example of , the video decoder 300 includes a coded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a decoded picture buffer (DPB) 314. Any or all of the CPB memory 320, the entropy decoding unit 302, the prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, the filter unit 312, and the DPB 314 can be implemented in one or more processors or processing circuits. For example, the units of the video decoder 300 can be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. In addition, the video decoder 300 may include additional or alternative processors or processing circuits to perform these and other functions.

[0104] The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include an addition unit to perform prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra-block copy unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0105] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of video decoder 300. The video bitstream may be obtained, for example, from computer readable medium 110 ( Figure 1 ) obtains video data stored in CPB memory 320. CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from an encoded video bitstream. Moreover, CPB memory 320 may store video data of syntax elements other than encoded and decoded pictures, such as temporary data representing outputs from various units of video decoder 300. DPB 314 typically stores decoded pictures, and video decoder 300 may output and / or use decoded pictures as reference video data when decoding subsequent data or pictures of the encoded video bitstream. CPB memory 320 and DPB 314 may be formed by any of a variety of memory devices, such as DRAM, including SDRAM, MRAM, RRAM or other types of storage devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip relative to those components.

[0106] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) retrieves the coded video data. That is, the memory 120 may store the data as described above with the CPB memory 320. Likewise, when some or all of the functions of the video decoder 300 are implemented in software to be executed by the processing circuitry of the video decoder 300, the memory 120 may store instructions to be executed by the video decoder 300.

[0107] Figure 4 The various units shown in FIG. 3 are shown to aid in understanding the operations performed by the video decoder 300. These units may be implemented as fixed function circuits, programmable circuits, or a combination thereof. Figure 3, fixed-function circuits refer to circuits that provide specific functions and are preset in executable operations. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functionality in executable operations. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally unchanged. In some examples, one or more units may be different circuit blocks (fixed-function or programmable), and in some examples, one or more units may be integrated circuits.

[0108] The video decoder 300 may include an ALU, an EFU, a digital circuit, an analog circuit, and / or a programmable core formed by a programmable circuit. In an example where the operation of the video decoder 300 is performed by software executed on a programmable circuit, an on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by the video decoder 300.

[0109] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode the video data to reproduce the syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0110] Typically, the video decoder 300 reconstructs a picture block by block. The video decoder 300 may perform a reconstruction operation on each block individually (where a block currently being reconstructed (ie, decoded) may be referred to as a "current block").

[0111] The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of the quantized transform coefficient block and transform information, such as a quantization parameter (QP) and / or (multiple) transform mode indications. The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization, and likewise, determine a degree of inverse quantization of the inverse quantization unit 306 to apply. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block including the transform coefficients.

[0112] After inverse quantization unit 306 forms the transform coefficient block, inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block. In some examples, inverse transform processing unit 308 may not apply an inverse transform, for example, when encoding and decoding the residual according to a transform skip mode.

[0113] As described above, VVC Draft 7 specifies two different residual coding methods. In one example, the video decoder 300 is configured to decode a block of residual video data using a transform skip (TS) residual codec. In TS residual codec, the video decoder 300 is configured not to apply an inverse transform to the residual block using an implicitly or explicitly determined transform, such as a discrete cosine transform (DCT-2). That is, the video decoder 300 does not perform an inverse transform on the residual block. Therefore, the residual is decoded in the spatial domain.

[0114] For example, refer to Figure 4 , the operation of the inverse transform processing unit 308 can be skipped. In one example, the video decoder 300 can determine the use of TS residual codec from the transform skip flag. For example, the syntax element transform_skip_flag[x0][y0][cIdx] specifies whether the transform is applied to the associated transform block (e.g., the residual block). A value of 0 indicates that the transform can be skipped in some cases (e.g., the transform skip is based on other syntax elements). A value of 1 indicates that the transform process is skipped.

[0115] In the case where TS residual codec is not used, the video decoder 300 can be configured to use a different residual codec method, which is called regular residual codec (RRC) or transform residual codec. Figure 4 When performing conventional residual coding, the operation of the inverse transform processing unit 308 is performed as described above and in further detail below.

[0116] In some examples, such as in VVC draft 7, the video decoder 300 is configured to determine the use of TS residual codec or conventional residual codec based on whether the transform is skipped before the residual and / or whether block differential pulse code modulation (BDPCM) is used. Both TS residual codec and conventional residual codec can be used for the luminance and chrominance components of the video codec block.

[0117] As will be described in more detail below, the present disclosure describes a variety of techniques for determining a residual codec method based on a QP value. For example, the video decoder 300 can be configured to determine a quantization parameter (QP) value for a block of video data, determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec, and decode the residual of the block of video data using the determined residual codec method. The techniques of the present disclosure can increase codec efficiency and / or reduce a singularization overhead for indicating a residual codec method.

[0118] Prediction processing unit 304 generates a block of prediction values ​​based on the prediction information syntax elements entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax elements indicate that the current block is inter-predicted, motion compensation unit 316 may generate the block of prediction values. In this case, the prediction information syntax elements may indicate a reference picture in DPB 314 from which the reference block is retrieved, and a motion vector that identifies the position of the reference block in the reference picture relative to the position of the current block in the current picture. Motion compensation unit 316 may generally be substantially similar to the process described with respect to motion compensation unit 224 ( Figure 3 ) to perform the inter-frame prediction process in the manner described.

[0119] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 can generate a prediction value block according to the intra-prediction mode indicated by the prediction information syntax element. Likewise, the intra-prediction unit 318 can generally generate a prediction value block in a manner substantially similar to that described with respect to the intra-prediction unit 226 ( Figure 3 ) to perform the intra prediction process. The intra prediction unit 318 can retrieve data of neighboring samples of the current block from the DPB 314.

[0120] The reconstruction unit 310 may reconstruct the current block using the prediction value block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction value block to reconstruct the current block.

[0121] The filter unit 312 may perform one or more filter operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along the edges of the reconstructed block. The operations of the filter unit 312 need not be performed in all examples.

[0122] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in examples where the operation of the filter unit 312 is not performed, the reconstruction unit 310 may store the reconstructed block to the DPB 314. In examples where the operation of the filter unit 312 is performed, the filter unit 312 may store the filtered reconstructed block to the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of the current picture for intra-frame prediction and previously decoded pictures for subsequent motion compensation. In addition, the video decoder 300 may output the decoded pictures from the DPB for subsequent presentation on a display such as a Figure 1 on a display device 118 of the display device.

[0123] In this way, the video decoder 300 represents an example of a video decoding device, which includes a memory configured to store video data, and one or more processing units implemented in a circuit and configured to determine a quantization parameter (QP) value for a block of video data; determine a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and encode a residual of the block of video data using the determined residual codec method.

[0124] In video codecs such as HEVC and VVC draft 7, a quantization parameter (QP) adjusts the amount of spatial detail retained. If a relatively small QP value is used, more information is saved at the expense of a reduced bit rate. Similarly, a relatively large QP value increases quantization and generally results in a higher bit rate. However, greater quantization via larger QP values ​​also reduces the visual statistical quality of the compressed image. Therefore, the video encoder 200 can be configured to determine a QP value so that there is a trade-off between visual quality and bit rate. The video encoder 200 can be configured to signal the determined QP value to the video decoder 300, or the video decoder 300 can be configured to predict the determined QP value from previous frames and other statistics within the compression framework.

[0125] VVC Draft 7 specifies two different residual coding methods. In one example, the video encoder 200 and the video decoder 300 can be configured to encode and decode blocks of residual video data using transform skip (TS) residual coding. In TS residual coding, the video encoder 200 and the video decoder 300 are configured not to transform the residual blocks using an implicit or explicitly determined transform, such as discrete cosine transform (DCT-2). That is, the video encoder 200 and the video decoder 300 do not perform a transform on the residual blocks. Therefore, the residual is encoded and decoded in the spatial domain.

[0126] For example, refer to Figure 3 and Figure 4 , the operations of the transform processing unit 206, the inverse transform processing unit 212, and the inverse transform processing unit 308 may be skipped. In one example, the video encoder 200 may signal the use of TS residual codec using a transform skip flag. For example, the syntax element transform_skip_flag[x0][y0][cIdx] specifies whether a transform is applied to an associated transform block (e.g., a residual block). A value of 0 indicates that the transform may be skipped in some cases (e.g., the transform skip is based on other syntax elements). A value of 1 indicates that the transform process is skipped.

[0127] In the case where TS residual codec is not used, the video encoder 200 and the video decoder 300 may be configured to use a different residual codec method, which is referred to as regular residual codec (RRC) or transform residual codec. Figure 3 and Figure 4 , when conventional residual coding and decoding is performed, the operations of the transform processing unit 206, the inverse transform processing unit 212, and the inverse transform processing unit 308 are performed as described above.

[0128] In some examples, such as in VVC draft 7, the video encoder 200 and the video decoder 300 are configured to determine the use of TS residual codec or normal residual codec based on whether the transform is skipped and / or block differential pulse code modulation (BDPCM) is used before residual codec (e.g., at the video encoder 200), or after residual codec (e.g., at the video decoder 300). Both TS residual codec and normal residual codec can be used for luma and chroma components of a video codec block.

[0129] The present disclosure describes a variety of techniques for determining a residual codec method based on a quantization parameter (QP) value. In some examples, the video encoder 200 and / or the video decoder 300 may be configured to use the QP value alone when determining the residual codec method to use. In other examples, the video encoder 200 and / or the video decoder 300 may be configured to use the QP value in combination with other codec information (e.g., a flag) to determine the residual codec method. The techniques of the present disclosure may increase codec efficiency and / or reduce the overhead of singularization for indicating the residual codec method.

[0130] Example 1

[0131] In a first example of the present disclosure, the video encoder 200 and / or the video decoder 300 may be configured to use a QP value, which is used to quantize a block of video data to determine which residual codec method to use for residual codec. For example, if the QP value is less than or equal to a threshold value such as 4, the video encoder 200 and / or the video decoder 300 may be configured to encode and decode the residual block using a conventional residual codec, instead of using another residual codec method such as TS residual codec.

[0132] If the QP value for the block is greater than the threshold, the video encoder 200 and / or the video decoder 300 may be configured to encode and decode the residual block using TS residual codec. The video encoder 200 and / or the video decoder 300 may be configured to determine the residual codec techniques for the luminance and chrominance components individually or together. That is, in some examples, the video encoder 200 and the video decoder 300 may use different residual codec methods for the corresponding luminance and chrominance codec blocks. In other examples, the video encoder 200 and the video decoder 300 may use the same residual codec method for the corresponding luminance and chrominance codec blocks. The techniques described in Example 1 may be used for both lossy and lossless codecs. An example lossless codec mode may include a transform quantization bypass codec mode in which both transform and quantization are bypassed. Another example lossless codec mode may be a codec mode in which a transform is skipped (e.g., a transform skip mode), which is combined with a quantization step size of 1.

[0133] Example 2

[0134] In a second example of the present disclosure, the video encoder 200 may be configured to signal side flag information (e.g., syntax elements), where in addition to the techniques of Example 1, the side information may be used to determine a residual codec method. For example, if the video encoder 200 signals a transform skip (TS) flag for a codec block (e.g., a residual block), and the QP value for the block is less than a threshold value (e.g., 4), the video decoder 300 may be configured to determine that conventional residual codec (e.g., transform residual codec) is used for the block. This is illustrated by the following syntax, which is also shown in Table 1 below:

[0135]

[0136] In the above syntax, if the value of the transform skip flag is 1, indicating that the transform can be skipped, and the value of the QP is greater than 4 (ie, QP>4), the video decoder 300 will determine to use the transform skip residual coding (residual_ts_coding) to decode the residual block. Otherwise, the video decoder 300 will determine to use the conventional residual coding (e.g., residual_coding) to decode the residual block.

[0137] In another example, if the BDPCM flag is non-zero (e.g., indicating that BDPCM mode is used) and the QP value for the block is less than or equal to a threshold value (e.g., 4), the video decoder 300 can determine that the residual codec method is conventional residual codec. The standard in Example 2 can correspond to a lossless or near-lossless scene, for which conventional residual codec can be superior to TS residual codec (e.g., in terms of bit rate and / or visual quality). Furthermore, the video encoder 200 and / or the video decoder 300 can be configured to determine the residual codec technique for the luma and chroma channels separately or together. The techniques described in Example 2 can be used for both lossy and lossless codecs.

[0138] Example 3

[0139] In a third example of the present disclosure, the video encoder 200 and / or the video decoder 300 may be configured to perform additional operations (such as residual rotation) of the prediction or transform residual based on the QP value of the block compared to the threshold. In one example, the residual rotation includes a block-wise rotation of the residual values ​​by 90 degrees or N degrees, where N may be specified by the video encoder 200. The video encoder 200 and / or the video decoder 300 may be configured to encode and decode the rotated residual using the determined residual encoding and decoding method (e.g., conventional residual encoding and decoding or TS residual encoding and decoding). The techniques of Example 3 may be used independently or in combination with any combination of Examples 1 and 2.

[0140] In another example, if the QP value is less than a threshold (e.g., 4) and the TS flag is signaled as 1, the video encoder 200 can be configured to disable last position signaling in conventional residual codec to reduce signaling overhead when conventional residual codec as in Example 2 can be selected as the residual codec method.

[0141] Example 4

[0142] In a fourth example of the present disclosure, the video encoder 200 and / or the video decoder 300 may be configured to use the QP value to determine an appropriate context (e.g., a probability model) for entropy coding when using context adaptive binary arithmetic coding (CABAC). Based on the above detailed techniques for determining the residual coding method (e.g., Examples 1 and 2), the video encoder 200 and / or the video decoder 300 may be configured to assign a specific context set for coding and decoding a binary number of a syntax element indicating a residual value (e.g., for transform skip residual coding) and / or a transform coefficient (e.g., for conventional residual coding) when the QP value is less than a threshold (e.g., 4) and / or when the QP value is less than a threshold (e.g., 4) and the TS flag (transform_skip_flag) is 1. If the QP condition is not met, the video encoder 200 and / or the video decoder 300 may be configured to use a different context set for arithmetic coding. In general, the video encoder 200 and the video decoder 300 may be configured to use a specific context set to encode and decode residual values ​​and / or transform coefficients based on the residual encoding and decoding method used.

[0143] Example 5

[0144] In a fifth example of the present disclosure, the video encoder 200 may be configured to signal a block level flag (e.g., a transform unit or codec unit level) based on a QP value. If the QP value is less than a threshold value (e.g., 4), the video encoder 200 may signal a block level flag to provide more effective control of the lossless codec block. For example, the HEVC standard includes a transform quantization bypass flag indicating that the block is losslessly coded (e.g., skipping both transform and quantization). Since the flag indicates a lossless mode, specific lossless codec tools and operations may be performed. Signaling a transform quantization bypass flag or a similar flag at a low level (e.g., a block level) may depend on the QP value. The flag may be used to (i) determine an appropriate residual codec method (e.g., conventional residual codec or TS residual codec) as in Example 1 or Example 2, and / or (ii) perform other operations, such as residual rotation or disabling last position signaling as in Example 3.

[0145] Table 1 below is taken from Section 7.3.9.10 of VVC Draft 7. Table 1 Modifications according to the techniques of the present disclosure are shown in brackets <add> and< / add> between.

[0146] Table 1-7.3.9.10 Transformation unit syntax

[0147]

[0148]

[0149] The variable qP indicates the value of the quantization parameter. The condition transform_skip_flag[xC][yC][2]&&(qP<=4) indicates that the QP value is less than or equal to 4, and transform_skip_flag[xC][yC][2] indicates that the TS flag is 1.

[0150] Example 6

[0151] In a sixth example of the present disclosure, the video encoder 200 may be configured to use a QP value to signal a low-level flag or a high-level flag (e.g., at a transform unit or codec unit block level) to indicate a residual codec method and / or whether the block is lossy, near-lossless, or lossless. If a condition or threshold based on a QP value is not met, the video encoder 200 may not signal such a flag. Otherwise, if the QP condition is met, the video encoder 200 may signal a flag to indicate 1) which residual codec method to use, and / or to indicate 2) whether the block is lossy, near-lossless, or lossless.

[0152] Table II below is taken from Section 7.3.9.10 of VVC Draft 7. Modifications are shown in brackets <add> and< / add> between.

[0153] Table II-7.3.9.10 Transformation unit syntax

[0154]

[0155]

[0156]

[0157] The variable qP indicates the value of the quantization parameter. The syntax element transform_skip_flag[xC][yC][2]&&(qP>4) indicates the condition that the QP value is less than or equal to 4 and transform_skip_flag[xC][yC][2] indicates the TS flag is 1.

[0158] Figure 5 2 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although with respect to the video encoder 200 ( Figure 1 and Figure 3 ), but it should be understood that other devices may be configured to perform the same Figure 5 A similar approach to the one used in this paper.

[0159] In this example, the video encoder 200 initially predicts the current block (350). For example, the video encoder 200 may form a prediction block for the current block. The video encoder 200 may then calculate a residual block for the current block (352). In order to calculate the residual block, the video encoder 200 may calculate the difference between the original uncoded block and the prediction block for the current block. The video encoder 200 may then transform and quantize the coefficients of the residual block (354). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or after the scan, the video encoder 200 may entropy encode the transform coefficients (358). For example, the video encoder 200 may use CAVLC or CABAC to encode the transform coefficients. The video encoder 200 may then output entropy encoded data for the block (360).

[0160] Figure 6 is a flowchart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although with respect to the video decoder 300 ( Figure 1 and Figure 4 ), but it should be understood that other devices may be configured to perform the same Figure 6 A similar approach to the one used in this paper.

[0161] The video decoder 300 may receive entropy coded data (such as entropy coded prediction information) for a current block and entropy coded data for coefficients of a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy coded data to determine prediction information for the current block and to reproduce coefficients of the residual block (372). The video decoder 300 may predict the current block (374), for example, using an intra-frame or inter-frame prediction mode indicated by the prediction information for the current block to calculate a prediction block for the current block. The video decoder 300 may then inverse scan the reproduced coefficients (376) to create a quantized transform coefficient block. The video decoder 300 may then inverse quantize and inverse transform the transform coefficients to produce a residual block (378). The video decoder 300 may ultimately decode the current block (380) by combining the prediction block and the residual block.

[0162] Figure 7 is a flowchart illustrating another example decoding method of the present disclosure. Figure 7 The techniques may be performed by one or more structural components of the video decoder 300 .

[0163] In one example of the present disclosure, the video decoder 300 may be configured to determine a quantization parameter (QP) value for a block of video data (700). The video decoder 300 may then determine a residual coding method from a plurality of residual coding methods based on the QP value, wherein the plurality of residual coding methods include a transform skip (TS) residual coding and a conventional residual coding (702). The video decoder may then decode the residual of the block of video data using the determined residual coding method.

[0164] In one example, in order to determine the residual codec method from a plurality of residual codec methods based on the QP value, the video decoder 300 is configured to compare the QP value with a threshold value, and determine that the residual codec method is TS residual codec if the QP value is greater than the threshold value. Similarly, the video decoder 300 is configured to determine that the residual codec method is a conventional residual codec if the QP value is less than or equal to the threshold value. In one example, the threshold value is 4.

[0165] In another example, in order to determine the residual codec method from a plurality of residual codec methods based on the QP value, the video decoder 300 is configured to determine the residual codec method from a plurality of residual codec methods based on the QP value and the value of the transform skip flag. For example, the video decoder 300 is configured to determine that the residual codec method is the normal residual codec when the QP value is less than or equal to the threshold and the value of the transform skip flag indicates that the transform is not applied, and is configured to determine that the residual codec method is the TS residual codec when the QP value is greater than the threshold and the value of the transform skip flag indicates that the transform is not applied.

[0166] In another example, in order to determine the residual codec method from a plurality of residual codec methods based on the QP value, the video decoder 300 is configured to determine the residual codec method from a plurality of residual codec methods based on the QP value and the value of a block-based differential pulse code modulation (BDPCM) flag. In one example, the video decoder 300 is configured to determine that the residual codec method is a conventional residual codec if the QP value is less than or equal to a threshold and the value of the BDPCM flag indicates that BPCM codec is used. In another example, the video decoder 300 is configured to determine that the residual codec method is TS residual codec if the QP value is greater than a threshold and the value of the BDPCM flag indicates that BPCM codec is used.

[0167] In another example of the present disclosure, the video decoder 300 is configured to determine an additional operation to be performed on a residual of a block of video data based on the QP value, wherein the additional operation includes one or more of residual rotation or prediction of a transform residual. The video decoder 300 may also be configured to disable decoding of the last position of transform coefficient signaling based on a transform skip flag indicating that a transform is skipped and the determined residual codec method is a conventional residual codec.

[0168] In another example, the video decoder 300 is configured to determine a context of a binary of a syntax element indicating a residual value for a block of video data based on a QP value, and entropy decode the binary of the syntax element indicating a residual value for a block of video data using the determined context.

[0169] In another example, the video decoder 300 is configured to decode a flag based on the QP value, wherein the flag indicates one or more of residual coding methods, or whether a block of video data is lossy, near-lossless, or lossless.

[0170] Other illustrative examples of the disclosure are described below.

[0171] Item 1 - A method for encoding and decoding video data, the method comprising: determining a quantization parameter (QP) value for a block of video data; determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include a transform skip (TS) residual codec and a conventional residual codec; and encoding and decoding a residual of the block of video data using the determined residual codec method.

[0172] Clause 2 - A method as in clause 1, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value comprises: comparing the QP value with a threshold; and when the QP value is greater than the threshold, determining that the residual coding method is TS residual coding.

[0173] Clause 3 - A method as in any one of clauses 1 and 2, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value comprises: comparing the QP value with a threshold; and when the QP value is less than or equal to the threshold, determining that the residual coding method is a conventional residual coding method.

[0174] Clause 4 - A method as in any combination of clauses 1 to 3, wherein determining the residual codec method from a plurality of residual codec methods based on the QP value comprises: determining the residual codec method from a plurality of residual codec methods based on the QP value and a value of a transform skip flag.

[0175] Clause 5 - A method as in Clause 4, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value and the value of the transform skip flag comprises: when the QP value is less than or equal to a threshold and the value of the transform skip flag is 1, determining that the residual coding method is a normal residual coding method.

[0176] Clause 6-A method as in Clause 4, wherein determining the residual coding method from multiple residual coding methods based on the QP value and the value of the transform skip flag includes: when the QP value is greater than a threshold and the value of the transform skip flag is 1, determining that the residual coding method is TS residual coding.

[0177] Clause 7 - A method as any combination of clauses 1 to 3, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value comprises: determining the residual coding method from a plurality of residual coding methods based on the QP value and a value of a block-based differential pulse codec modulation (BDPCM) flag.

[0178] Clause 8 - A method as in Clause 7, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value and the value of the BDPCM flag comprises: when the QP value is less than or equal to a threshold and the value of the BDPCM flag is 1, determining that the residual coding method is a normal residual coding method.

[0179] Clause 9 - A method as in Clause 7, wherein determining the residual coding method from a plurality of residual coding methods based on the QP value and the value of the BDPCM flag comprises: when the QP value is greater than a threshold and the value of the BDPCM flag is 1, determining that the residual coding method is a normal residual coding method.

[0180] Clause 10 - The method of any combination of clauses 1 to 9, further comprising: determining, based on the QP value, an additional operation to be performed on a residual of the block of video data.

[0181] Clause 11 - The method of clause 10, wherein the additional operation comprises one or more of a rotation of the residual or a prediction of a transformed residual.

[0182] Clause 12 - The method of any combination of clauses 1 to 11, further comprising: disabling last position signaling if the transform skip flag is 1 and the determined residual codec method is normal residual codec.

[0183] Clause 13 - The method of any combination of clauses 1 to 12, further comprising: determining a context for a binary bit of a residual of a block of video data based on the QP value; and entropy encoding and decoding the binary bit of the residual of the block of video data using the determined context.

[0184] Clause 14 - The method of any combination of clauses 1 to 13, further comprising: encoding and decoding a block level lossless codec flag based on the QP value.

[0185] Clause 15—A method as in any combination of clauses 1 to 14, wherein the threshold is 4.

[0186] Clause 16—The method of any combination of clauses 1 to 15, wherein the block of video data is one of a luma block of video data or a chroma block of video data.

[0187] Clause 17 - The method of any combination of clauses 1 to 16, further comprising: encoding the block of video data using one of a lossy codec or a lossless codec.

[0188] Clause 18 - A method as any combination of clauses 1 to 17, further comprising: a QP value based codec flag, wherein the flag indicates one or more of the residual codec methods, and / or whether a block of video data is lossy coded, near-lossless coded, or lossless coded.

[0189] Clause 19-A method as defined in any combination of clauses 1 to 18.

[0190] Clause 20-A method as in any one of clauses 1 to 19, wherein encoding and decoding includes decoding.

[0191] Clause 21 - A method as in any one of clauses 1 to 19, wherein encoding and decoding includes encoding.

[0192] Clause 22 - An apparatus for encoding and decoding video data, the apparatus comprising one or more components for performing the method of any one of clauses 1 to 21.

[0193] Clause 23—The apparatus of clause 22, wherein the one or more components include one or more processors implemented in circuitry.

[0194] Clause 24-A device as in any one of clauses 22 and 23, further comprising: a memory for storing video data.

[0195] Clause 25 - The apparatus of any of clauses 22 to 24, further comprising: a display configured to display the decoded video data.

[0196] Clause 26 - The device of any of clauses 22 to 25, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0197] Clause 27 - A device as in any of clauses 22 to 26, wherein the device comprises a video decoder.

[0198] Clause 28 - A device as in any of clauses 22 to 27, wherein the device comprises a video encoder.

[0199] Clause 29 - A computer-readable storage medium having stored thereon instructions which, when executed, cause one or more processors to perform the method of any of clauses 1 to 21.

[0200] It should be appreciated that, depending on the example, certain actions or events of any of the techniques described herein may be performed in a different sequence, may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary to practice the techniques). Furthermore, in some examples, actions or events may be performed simultaneously rather than sequentially, such as through multithreading, interrupt processing, or multiple processors.

[0201] 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 sent via 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 corresponding to a tangible medium such as a data storage medium, or a communication medium including any medium that facilitates the transfer of a computer program from one location to another, such as according to a communication protocol. In this manner, a computer-readable medium may generally correspond to (1) a non-temporary 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 techniques described in the present disclosure. A computer program product may include a computer-readable medium.

[0202] As an example, and not a limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, flash memory or any other medium that can be used to store the required program code in the form of instructions or data structures and can be accessed by a computer. Moreover, any connection is properly referred to as a computer-readable medium. As an example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (such as infrared, radio and microwave) is used to send instructions from a website, server or other remote source, the coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (such as infrared, radio and microwave) is included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals or other temporary media, but point to non-temporary tangible storage media. As used herein, disks and optical disks include compact disks (CDs), laser optical disks, optical optical disks, digital versatile disks (DVDs), floppy disks and blue-ray disks, where disks usually reproduce data magnetically, and optical disks use lasers to reproduce data optically. Combinations of the above should also be included within the scope of computer-readable media.

[0203] Instructions may be executed by one or more processors such as one or more DSPs, general-purpose microprocessors, ASICs, FPGAs, or other equivalent integrated or discrete logic circuits. Therefore, the terms "processor" and "processing circuit" as used herein may refer to any of the aforementioned structures or any other structures suitable for implementing the techniques described herein. In addition, in some aspects, the functions described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. In addition, the techniques may be fully implemented in one or more circuits or logic elements.

[0204] The techniques of the present disclosure may be implemented in a variety of devices or apparatuses, including wireless handheld devices, integrated circuits (ICs), or IC sets (e.g., chipsets). Various components, modules, or units are described in the present disclosure to emphasize the functional aspects of devices configured to perform the disclosed techniques, but are not necessarily required to be implemented by different hardware units. Instead, as described above, the various units may be combined in a codec hardware unit, or provided by a collection of interoperable hardware units (including one or more processors as described above) in combination with appropriate software and / or firmware.

[0205] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding video data, the method include: determining a quantization parameter (QP) value for a block of video data; Determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include transform skip TS residual codec and normal residual codec; and decoding a residual of the block of video data using the determined residual codec method, Wherein, determining the residual coding and decoding method from the multiple residual coding and decoding methods based on the QP value includes: comparing the QP value to a threshold; When the QP value is greater than the threshold, determining that the residual coding method is TS residual coding; and When the QP value is less than or equal to the threshold, it is determined that the residual coding method is a conventional residual coding method.

2. The method according to claim 1, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value includes: The residual coding method is determined from the plurality of residual coding methods based on the QP value and the value of the transform skip flag.

3. The method according to claim 2, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value and the value of the transform skip flag comprises: In a case where the QP value is less than or equal to the threshold and the value of the transform skip flag indicates that transform is not applied, it is determined that the residual coding method is normal residual coding.

4. The method according to claim 2, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value and the value of the transform skip flag comprises: In a case where the QP value is greater than the threshold and the value of the transform skip flag indicates that transform is not applied, it is determined that the residual coding method is TS residual coding.

5. The method according to claim 1, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value includes: The residual coding method is determined from the plurality of residual coding methods based on the QP value and a value of a block-based differential pulse codec modulation (BDPCM) flag.

6. The method according to claim 5, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value and the value of the BDPCM flag includes: In a case where the QP value is less than or equal to the threshold and the value of the BDPCM flag indicates that BPCM codec is used, it is determined that the residual codec method is normal residual codec.

7. The method according to claim 5, in, Determining the residual coding method from the plurality of residual coding methods based on the QP value and the value of the BDPCM flag includes: In a case where the QP value is greater than the threshold and the value of the BDPCM flag indicates that BPCM codec is used, it is determined that the residual codec method is TS residual codec.

8. The method of claim 1, further comprising: include: An additional operation to be performed on the residual of the block of video data is determined based on the QP value, wherein the additional operation includes one or more of residual rotation or prediction of a transformed residual.

9. The method of claim 1, further comprising: include: Decoding of a last position of transform coefficient signaling is disabled based on a transform skip flag indicating that transform is skipped and the determined residual codec method is normal residual codec.

10. The method of claim 1, further comprising: include: determining, based on the QP value, a binary context of a syntax element indicating a value of the residual for the block of video data; as well as The determined context is used to entropy decode the bins of the syntax element indicating the value of the residual for the block of video data.

11. The method of claim 1, further comprising: include: A flag is decoded based on the QP value, wherein the flag indicates one or more of: a residual codec method, or whether the block of video data is lossy, near-lossless, or lossless.

12. The method of claim 1, further comprising: include: A picture formed using the decoded residual is displayed.

13. A device configured to decode video data, the device include: a memory configured to store video data; as well as one or more processors implemented in circuitry and in communication with the memory, the one or more processors being configured to: determining a quantization parameter (QP) value for a block of video data; Determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include transform skip TS residual codec and normal residual codec; and decoding a residual of the block of video data using the determined residual codec method, In order to determine the residual coding method from the multiple residual coding methods based on the QP value, the one or more processors are further configured to: comparing the QP value to a threshold; When the QP value is greater than the threshold, determining that the residual coding method is TS residual coding; and When the QP value is less than or equal to the threshold, it is determined that the residual coding method is a conventional residual coding method.

14. The device according to claim 13, in, In order to determine the residual coding method from the plurality of residual coding methods based on the QP value, the one or more processors are further configured to: The residual coding method is determined from the plurality of residual coding methods based on the QP value and the value of the transform skip flag.

15. The device according to claim 14, in, To determine the residual coding method from the plurality of residual coding methods based on the QP value and the value of the transform skip flag, the one or more processors are further configured to: In a case where the QP value is less than or equal to the threshold and the value of the transform skip flag indicates that transform is not applied, it is determined that the residual coding method is normal residual coding.

16. The device according to claim 14, in, To determine the residual coding method from the plurality of residual coding methods based on the QP value and the value of the transform skip flag, the one or more processors are further configured to: In a case where the QP value is greater than the threshold and the value of the transform skip flag indicates that transform is not applied, it is determined that the residual coding method is TS residual coding.

17. The device according to claim 13, in, In order to determine the residual coding method from the plurality of residual coding methods based on the QP value, the one or more processors are further configured to: The residual coding method is determined from the plurality of residual coding methods based on the QP value and a value of a block-based differential pulse codec modulation (BDPCM) flag.

18. The device according to claim 17, in, To determine the residual codec method from the plurality of residual codec methods based on the QP value and the value of the BDPCM flag, the one or more processors are further configured to: In a case where the QP value is less than or equal to the threshold and the value of the BDPCM flag indicates that BPCM codec is used, it is determined that the residual codec method is normal residual codec.

19. The device according to claim 17, in, To determine the residual codec method from the plurality of residual codec methods based on the QP value and the value of the BDPCM flag, the one or more processors are further configured to: In a case where the QP value is greater than the threshold and the value of the BDPCM flag indicates that BPCM codec is used, it is determined that the residual codec method is TS residual codec.

20. The apparatus of claim 13, wherein the one or more processors are further configured to: determining, based on the QP value, an additional operation to be performed on the residual of the block of video data, in, The additional operations include one or more of residual rotation or prediction of the transformed residual.

21. The apparatus of claim 13, wherein the one or more processors are further configured to: Decoding of transform coefficient last position signaling is disabled based on a transform skip flag indicating that transform is skipped and the determined residual codec method is normal residual codec.

22. The apparatus of claim 13, wherein the one or more processors are further configured to: determining, based on the QP value, a binary context of a syntax element indicating a value of the residual for the block of video data; and The determined context is used to entropy decode the bins of the syntax element indicating a value of the residual for the block of video data.

23. The apparatus of claim 13, wherein the one or more processors are further configured to: decoding a flag based on the QP value, in, The flag indicates one or more of: a residual codec method, or whether the block of video data is lossy coded, near-lossless coded, or lossless coded.

24. The device of claim 13, further comprising: include: A display is configured to display a picture formed using the decoded residual.

25. A device configured to decode video data, the device include: means for determining a quantization parameter QP value for a block of video data; means for determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include transform skip TS residual codec and normal residual codec; and means for decoding a residual of said block of video data using the determined residual codec method, The component for determining the residual coding from the plurality of residual coding methods based on the QP value includes: means for comparing the QP value to a threshold; The method is configured to determine that the residual coding method is TS residual coding when the QP value is greater than the threshold, and to determine that the residual coding method is normal residual coding when the QP value is less than or equal to the threshold.

26. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to decode video data: determining a quantization parameter (QP) value for a block of video data; Determining a residual codec method from a plurality of residual codec methods based on the QP value, wherein the plurality of residual codec methods include transform skip TS residual codec and normal residual codec; and decoding a residual of the block of video data using the determined residual codec method, Wherein, in order to determine the residual codec from the plurality of residual codec methods based on the QP value, the instructions cause the one or more processors to: comparing the QP value to a threshold; The method of determining that the residual coding method is TS residual coding when the QP value is greater than the threshold value and the method of determining that the residual coding method is normal residual coding when the QP value is less than or equal to the threshold value are components.

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