Signaling a coding scheme for residual values ​​in transform skip for video coding

Abstract

An example method for decoding video data includes: receiving one or more syntax elements of the video data, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a residual value of a block of the video data decoded in a transform skip situation, wherein the residual value indicates a difference between the block and a prediction block, and wherein, in the transform skip, the residual value is not transformed from a sample domain to a frequency domain. The method includes: determining a type of decoding scheme to be applied to the residual value based on the one or more syntax elements, determining the residual value based on the determined type of decoding scheme, and reconstructing the block based on the determined residual value and the prediction block.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 17 / 066,308, filed on October 8, 2020, which claims priority to U.S. Provisional Application No. 62 / 914,315, filed on October 11, 2019, both of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to video encoding and video decoding. Background Art

[0004] Digital video capabilities may be incorporated into a wide variety of devices, including digital televisions, digital live 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 coding 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 Coding (AVC)), ITU-T H.265 / High Efficiency Video Coding (HEVC), and extensions of such standards). By implementing such video coding techniques, video devices may more efficiently send, receive, encode, decode, and / or store digital video information.

[0005] 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 coding tree units (CTUs), coding units (CUs), and / or coding nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial predictions relative to reference samples in neighboring blocks in the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial predictions relative to reference samples in neighboring blocks in the same picture or temporal predictions relative 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

[0006] In general, the present disclosure describes techniques for lossless coding schemes and signaling for video decoding. There may be at least two coding schemes for decoding (e.g., encoding or decoding) residual values ​​of video data. The first coding scheme is transform coefficient coding (TRCC), and the second coding scheme is transform skip residual coding (TSRC). In some cases, TSRC may only be used for blocks of video data that are decoded in the case of transform skipping (e.g., the residual values ​​for the block are not transformed from the sample domain to the frequency domain). However, even for blocks that are skipped by transforms, there may be benefits to using TRCC. The present disclosure describes exemplary techniques for using TRCC even for blocks that are skipped by transforms, thereby improving the overall decoding process.

[0007] In one example, the present disclosure describes a method for decoding video data, the method comprising: receiving one or more syntax elements of the video data from a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a residual value of a block of the video data decoded in a transform skip case, wherein the residual value indicates a difference between the block and a prediction block, and wherein, in the transform skip, the residual value is not transformed from a sample domain to a frequency domain; determining a type of decoding scheme to be applied to the residual value based on the one or more syntax elements; determining the residual value based on the determined type of decoding scheme; and reconstructing the block based on the determined residual value and the prediction block.

[0008] In another example, the present disclosure describes a method for encoding video data, the method comprising: determining a residual value based on a difference between a block of video data to be decoded and a predicted block in a transform skip, wherein in the transform skip, the residual value is not transformed from a sample domain to a frequency domain; determining a type of decoding scheme between a first type of decoding scheme and a second type of decoding scheme to be applied to the residual value; encoding the residual value based on the determined type of decoding scheme; and signaling one or more syntax elements of the video data into a video bitstream, the one or more syntax elements indicating whether the first type of decoding scheme or the second type of decoding scheme is applied to the residual value.

[0009] In another example, the present disclosure describes a device for decoding video data, the device comprising: a memory configured to store video data; and a processing circuit coupled to the memory and configured to: receive one or more syntax elements of the video data from a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a block of the video data decoded in a transform skip case, wherein the residual value indicates a difference between the block and a predicted block, and wherein, in the transform skip, the residual value is not transformed from a sample domain to a frequency domain; determine a type of decoding scheme to be applied to the residual value based on the one or more syntax elements; determine the residual value based on the determined type of decoding scheme; and reconstruct the block based on the determined residual value and the predicted block.

[0010] In another example, the present disclosure describes a computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to perform the following operations: receive one or more syntax elements of video data from a video bitstream, the one or more syntax elements indicating whether to apply a first type of decoding scheme or a second type of decoding scheme to a block of video data decoded in a transform skip case, wherein the residual value indicates a difference between the block and a predicted block, and wherein, in the transform skip, the residual value is not transformed from a sample domain to a frequency domain; determine a type of decoding scheme to be applied to the residual value based on the one or more syntax elements; determine the residual value based on the determined type of decoding scheme; and reconstruct the block based on the determined residual value and the predicted block.

[0011] In another example, the present disclosure describes an apparatus for decoding video data, comprising: a unit for receiving one or more syntax elements of the video data from a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a block decoded in a transform skip case, wherein the residual value indicates a difference between the block and a predicted block, and wherein, in the transform skip, the residual value is not transformed from a sample domain to a frequency domain; a unit for determining a type of decoding scheme to be applied to the residual value based on the one or more syntax elements; a unit for determining the residual value based on the determined type of decoding scheme; and a unit for reconstructing the block based on the determined residual value and the predicted block.

[0012] 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

[0013] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0014] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and a corresponding coding tree unit (CTU).

[0015] Figure 3 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0016] Figure 4 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0017] Figure 5 is a flow chart illustrating an example method for encoding a current block.

[0018] Figure 6 is a flow chart illustrating an example method for decoding a current block of video data. DETAILED DESCRIPTION

[0019] In video decoding technology, a video encoder determines residual information (e.g., residual values) indicating the difference between samples of a current block and samples of a prediction block. In some cases, the video encoder transforms sample values ​​of the residual information (e.g., residual values) in a sample domain (also referred to as a pixel domain) into coefficient values ​​in a frequency domain. In some examples, the coefficient values ​​are then quantized and entropy encoded into a bitstream. The video decoder receives the quantized coefficient values ​​from the bitstream. The video decoder inversely quantizes the coefficient values ​​and inversely transforms the inversely quantized coefficient values ​​to generate residual values. The video decoder adds the residual values ​​to the prediction block to reconstruct the current block.

[0020] In some cases, transform and / or quantization may be lossy. For example, some residual values ​​may be lost in the transform and / or quantization steps. Therefore, the residual values ​​generated by the video decoder may be different from the residual values ​​generated by the video encoder. Therefore, in some cases, the current block reconstructed by the video decoder may be different from the original current block encoded by the video encoder.

[0021] Although there may be some loss in the encoding process, the current block reconstructed by the video decoder tends to be sufficiently identical to the original current block so that there is little degradation in visual quality. However, in some cases, it may be desirable to include lossless video coding tools so that the residual values ​​are almost lossless (e.g., so that the residual values ​​at the video encoder are more similar to the residual values ​​at the video decoder than with lossy video coding techniques).

[0022] In some cases, for lossless video coding, the video encoder may skip a transform step for a particular block. The video encoder may signal information indicating that a transform is skipped for a particular block. The video decoder may determine to skip the transform based on the signaled information. In some examples, the video decoder may implicitly determine whether to skip the transform for a block without the video encoder signaling information indicating that a transform is skipped.

[0023] Residual values ​​can be decoded regardless of whether the transform is skipped. There are two exemplary schemes for decoding residual values: transform coefficient coding (TRCC) and transform skip (TS) residual coding (TSRC). In TRCC, the video encoder can determine the coefficient value (e.g., via a transform) based on the residual value, and entropy encode the information used to determine the coefficient value. For example, the video encoder can determine information such as the last significant coefficient value position, a significance map (e.g., information indicating which coefficient values ​​are not zero), coefficient levels (e.g., information indicating which coefficient values ​​have absolute values ​​greater than 1, greater than 2, etc.), and sign data (e.g., whether the coefficient value is negative or positive).

[0024] TSRC may be different from TRCC. In TSRC, there may be no signaling of the position of the last significant coefficient. In TSRC, information such as significance mapping, coefficient levels, and symbol data may be similar to TRCC. However, compared with TRCC, the context modeling and binarization for TSRC and the restrictions on the number of context decoding bins for each sample may be different. The above are some non-limiting examples of the differences and similarities between TSRC and TRCC. There may be other differences and other similarities. In addition, what is identified as the difference between TSRC and TRCC in some cases may be the same, while what is identified as the similarities between TSRC and TRCC in some cases may be different.

[0025] In some cases, TSRC may be used exclusively for residual coding of transform skip blocks. However, there may be benefits to using TRCC for transform skip blocks. The present disclosure describes exemplary techniques in which TSRC or TRCC may be used in situations where lossless coding techniques (e.g., transform skip) are implemented. In this way, the exemplary techniques may improve the operation of video encoders and video decoders by allowing TRCC or TSRC to be applied to residual values, which in turn may result in better video coding.

[0026] As an example, a video decoder may receive one or more syntax elements of video data from a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme (e.g., TRCC) or a second type of decoding scheme (e.g., TSRC) is applied to a residual value of a block decoded in a transform skip situation. As described above, the residual value indicates the difference between the block and the predicted block, and in a transform skip, the residual value is not transformed from a sample domain to a frequency domain (also referred to as a transform domain). In some examples, in order to receive the one or more syntax elements, the video decoder may receive a flag in a slice header indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a residual value of a block in a slice decoded in a transform skip situation.

[0027] The video decoder may determine the type of coding scheme to be applied to the residual value based on one or more syntax elements (e.g., determining whether TRCC or TSRC is to be used), and determine the residual value based on the determined type of coding scheme. For example, based on whether TRCC or TSRC is used to determine the residual value, the video decoder may parse values ​​such as the last significant value position, a significance map (e.g., information indicating which values ​​are not zero), coefficient levels (e.g., information indicating which values ​​have absolute values ​​greater than 1, greater than 2, etc.), sign data (e.g., whether the value is negative or positive), etc. The video decoder may reconstruct the block based on the determined residual value and the prediction block (e.g., adding the residual value to the prediction block to reconstruct the block).

[0028] The video encoder may determine a residual value based on a difference between a coded block and a predicted block in the case of transform skipping. In transform skipping, the residual value is not transformed from the sample domain to the frequency domain (eg, transform domain).

[0029] The video encoder may determine a type of decoding scheme between a first type of decoding scheme (e.g., TRCC) and a second type of decoding scheme (e.g., TSRC) to be applied to the residual value, and encode the residual value based on the determined type of decoding scheme. For example, based on whether the residual value is determined using TRCC or TSRC, the video encoder may signal values ​​such as the last significant value position, a significance map (e.g., information indicating which values ​​are non-zero), coefficient levels (e.g., information indicating which values ​​have absolute values ​​greater than 1, greater than 2, etc.), sign data (e.g., whether the value is negative or positive), etc.

[0030] The video encoder may signal one or more syntax elements of the video data in a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to the residual value. In some examples, to signal the one or more syntax elements, the video encoder may signal a flag in a slice header, the flag indicating whether the first type of decoding scheme or the second type of decoding scheme is applied to the residual value of the block decoded with transform skipping.

[0031] 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. In general, the techniques of the present disclosure relate to decoding (encoding and / or decoding) video data. Generally, video data includes any data used to process video. Thus, video data can include original unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (e.g., signaling data).

[0032] like Figure 1 As shown in , 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 variety of devices, including desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets such as smart phones, televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0033] exist Figure 1 In 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, the video encoder 200 of source device 102 and the video decoder 300 of destination device 116 can be configured to apply techniques for lossless decoding and signaling. 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, the source device and the 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 be docked with an external display device instead of including an integrated display device.

[0034] like Figure 1 The system 100 shown is only an example. In general, any digital video encoding and / or decoding device can be used to generate decoded video data for transmission to the destination device 116. The present disclosure refers to a "decoding" device as a device that performs decoding (e.g., encoding and / or decoding) of data. Therefore, the video encoder 200 and the video decoder 300 represent examples of decoding devices (specifically, 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.

[0035] Typically, the video source 104 represents the source of video data (i.e., the original, undecoded video data), and provides a series of pictures (also referred to as "frames") of the order of the video data to the video encoder 200, which encodes the data for the pictures. The video source 104 of the source device 102 may include a video capture device, such as a camera, a video archive unit containing previously captured original video, and / or a video feed interface for 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 may encode 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 decoding order for 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 to be received and / or retrieved by, for example, input interface 122 of destination device 116 .

[0036] 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. In addition or alternatively, the memories 106, 120 can store software instructions that can be executed by, for example, the video encoder 200 and the video decoder 300, respectively. Although the memory 106 and the memory 120 are shown as separate 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 memories for 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.

[0037] The computer-readable medium 110 may represent any type of medium or device capable of delivering 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 that enables the source device 102 to directly send the encoded video data 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 a 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, for example, a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form a portion 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 may be useful for facilitating communication from the source device 102 to the destination device 116.

[0038] 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.

[0039] 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) configured to provide file transfer protocol services (e.g., file transfer protocol (FTP) or 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 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 Real-Time Streaming (HLS), Real-Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, and the like.

[0040] 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 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.

[0041] 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), Advanced LTE, 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 TMStandards, etc.) to transmit data (such as encoded video data). In some examples, source device 102 and / or destination device 116 may include corresponding system-on-chip (SoC) devices. For example, source device 102 may include a SoC device for performing the functions assigned to video encoder 200 and / or output interface 108, and destination device 116 may include a SoC device for performing the functions assigned to video decoder 300 and / or input interface 122.

[0042] The techniques of the present disclosure may be applied to video 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.

[0043] The input interface 122 of the destination device 116 receives the 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 110 may include information signaled into the video bitstream, such as syntax elements defined by the video encoder 200 (which are also used by the video decoder 300): the syntax elements have values ​​that describe characteristics and / or processing of video blocks or other decoding units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays the 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 cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0044] Despite Figure 1 200 and 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 multiplexed streams including both audio and video in a common data stream. If applicable, the MUX-DEMUX units may follow the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

[0045] 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 can store instructions for the software in a suitable non-transitory computer-readable medium, and use one or more processors to execute the instructions in hardware 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, and any of the encoders or decoders can be integrated as part of a combined encoder / decoder (CODEC) in the corresponding device. The device including the video encoder 200 and / or the video decoder 300 can include an integrated circuit, a microprocessor, and / or a wireless communication device (e.g., a cellular phone).

[0046] The video encoder 200 and the video decoder 300 may operate according to a video coding standard such as ITU-T H.265 (also known as the High Efficiency Video Coding (HEVC) standard) or an extension thereof such as a multi-view and / or scalable video coding extension. Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary or industry standards such as ITU-T H.266, also known as Versatile Video Coding (VVC). The draft of the VVC standard is described in the 15th meeting of the Joint Video Experts Group (JVET) of ITU-T SG16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11 in Gothenburg, Sweden from July 3 to 12, 2019, JVET-O2001-vE, Bross et al., “Versatile Video Coding (Draft 6)” (hereinafter referred to as “VVC Draft 6”). The latest draft of the VVC standard is described in the 18th meeting of the Joint Video Experts Group (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, JVET-S2001-vA, Bross et al., "Versatile Video Coding (Draft 10)" (hereinafter referred to as "VVC Draft 10"), held by telephone from June 22 to July 1, 2020. However, the technology of the present disclosure is not limited to any specific decoding standard.

[0047] Typically, the video encoder 200 and the video decoder 300 can perform block-based decoding of the picture. The term "block" generally refers to a structure that includes data to be processed (e.g., to be 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 decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, instead of decoding red, green, and blue (RGB) data for samples of a picture, the video encoder 200 and the video decoder 300 can decode luminance and chrominance components, wherein the chrominance components may include both red hue and blue hue chrominance components. In some examples, the video encoder 200 converts the received RGB formatted data to a YUV representation before encoding, and the video decoder 300 converts the YUV representation to an RGB format. Optionally, a pre-processing and post-processing unit (not shown) can perform these conversions.

[0048] The present disclosure may generally relate to the decoding (e.g., encoding and decoding) of a picture to include the process of encoding or decoding data for the picture. Similarly, the present disclosure may relate to the decoding of a block of a picture to include the process of encoding or decoding data for the block (e.g., prediction and / or residual decoding). The encoded video bitstream generally includes a series of values ​​for syntax elements that represent decoding decisions (e.g., decoding modes) and partitioning of the picture into blocks. Therefore, references to decoding a picture or a block should generally be understood as decoding the values ​​of the syntax elements used to form the picture or the block.

[0049] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video decoder (such as the video encoder 200) partitions a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video decoder 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 decoder may further partition the PU and TU. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TU. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. An intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0050] 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 decoder (e.g., the video encoder 200) partitions a picture into a plurality of coding tree units (CTUs). The video encoder 200 may partition the CTU according to a tree structure (e.g., 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 partition 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 coding units (CUs).

[0051] 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) (also known as ternary tree (TT)) partitioning. A ternary tree or ternary tree partitioning is a partitioning in which a block is divided into three sub-blocks. In some examples, the ternary tree or ternary tree partitioning divides the block into three sub-blocks without dividing the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0052] 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 component and the 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 the respective chroma components).

[0053] The video encoder 200 and the video decoder 300 may be configured to use quadtree segmentation, QTBT segmentation, MTT segmentation, or other segmentation structures per HEVC. For purposes of explanation, a description of the techniques of the present disclosure is given with respect to QTBT segmentation. However, it should be understood that the techniques of the present disclosure may also be applied to video decoders configured to use quadtree segmentation or also use other types of segmentation.

[0054] Blocks (e.g., CTUs or CUs) may be grouped in a picture in various ways. As an example, a brick may refer to a rectangular area of ​​a CTU row within a particular tile in a picture. A tile may 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 height of the picture 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 width of the picture.

[0055] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. Tiles that are not partitioned into multiple bricks may also be referred to as bricks. However, bricks that are true subsets of tiles may not be referred to as tiles.

[0056] Tiles in a picture can also be arranged in slices. A slice can be an integer number of tiles of a picture that can be uniquely contained in a single network abstraction layer (NAL) unit. In some examples, a slice includes a continuous sequence of multiple complete tiles or only complete tiles of one tile.

[0057] This disclosure may use "N×N" and "N by N" interchangeably to refer to the sample size of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions, for example, 16×16 samples or 16 by 16 samples. Typically, a 16×16 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 need to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include N×M samples, where M is not necessarily equal to N.

[0058] The video encoder 200 encodes video data representing prediction and / or residual information (e.g., residual values) and other information for a CU. The prediction information indicates how the CU will be predicted in order to form a prediction block for the CU. The residual information (i.e., residual values) typically represent sample-by-sample differences between samples of the CU before encoding and the prediction block.

[0059] In order to predict a CU, the video encoder 200 can generally form a prediction block for the CU by inter-frame prediction or intra-frame prediction. Inter-frame prediction generally refers to predicting a CU based on data of a previously decoded picture, while intra-frame prediction generally refers to predicting a CU based on previously decoded 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 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 use 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 calculate a difference metric 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.

[0060] In some examples, VVC also provides 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).

[0061] To perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. In some examples, VVC provides sixty-seven intra prediction modes, including various directional modes, as well as planar modes and DC modes. Typically, the video encoder 200 selects an intra prediction mode that describes the neighboring samples of the current block according to which the samples of the current block (e.g., a block of a CU) are to be predicted. Assuming that the video encoder 200 decodes the CTU and CU 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.

[0062] The video encoder 200 encodes data representing a prediction mode for the current block. For example, for an inter-frame prediction mode, the video encoder 200 may encode data representing which of the various available inter-frame prediction modes is used and motion information for the corresponding mode. For unidirectional or bidirectional inter-frame prediction, for example, the video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. The video encoder 200 may use a similar mode to encode motion vectors for affine motion compensation mode.

[0063] 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 (such as a residual block) represents a sample-by-sample difference between a block and a prediction block for the block, which is formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to produce transformed data in a transform domain rather than in 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. In addition, the video encoder 200 may apply a secondary transform after the first 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.

[0064] In some examples, the transform of the residual data (e.g., the residual value) can be skipped. For example, in the case of applying lossless video decoding technology, the transform can be skipped. In such examples, the block being encoded can be referred to as a transform skipped block, a transform skipped block, or a block decoded with a transform skipped.

[0065] As described above, after any transformation to produce transform coefficients, the video encoder 200 can perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to potentially reduce the amount of data used to represent the transform coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all transform 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 of the value to be quantized. In some examples, the quantization step can be bypassed.

[0066] After quantization, the video encoder 200 may scan the transform coefficients (or residual sample values ​​in which the transform is skipped), thereby generating a one-dimensional vector from a two-dimensional matrix including quantized transform coefficients, or residual sample values ​​in which the transform is skipped and quantization is skipped, or residual quantized sample values ​​in which the transform is skipped but quantization is performed. The scanning of the transform coefficients may be designed to place higher energy (and therefore lower frequency) transform coefficients at the front of the vector and lower energy (and therefore higher frequency) transform coefficients at the back of the vector. In some examples, the video encoder 200 may scan the quantized transform coefficients using a predefined scanning 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.

[0067] 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). In examples where transforms and / or quantization are skipped, the video encoder 200 may entropy encode the one-dimensional vector of residual sample values ​​or residual quantized sample values. The video encoder 200 may also entropy encode values ​​of syntax elements used to describe metadata associated with the encoded video data for use by the video decoder 300 when decoding the video data.

[0068] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. 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.

[0069] The video encoder 200 may also generate syntax data (e.g., block-based syntax data, picture-based syntax data, and sequence-based syntax data) or other syntax data (e.g., sequence parameter set (SPS), picture parameter set (PPS), or video parameter set (VPS)) for the video decoder 300, for example, in a picture header, a block header, a slice header. Likewise, the video decoder 300 may decode such syntax data to determine how to decode the corresponding video data.

[0070] In this way, the video encoder 200 can generate a bitstream that includes encoded video data, such as a syntax element describing the partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual values ​​for the blocks. Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0071] 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 use CABAC to decode the values ​​of the syntax elements for the bitstream in a manner substantially similar to, but reverse to, the CABAC encoding process of the video encoder 200. The syntax elements may define information for partitioning of a picture into CTUs, and partitioning each CTU according to a corresponding partitioning structure (e.g., a QTBT structure) to define CUs of the CTU. The syntax elements may also define prediction and residual values ​​for a block (e.g., a CU) of video data.

[0072] The residual value may be represented by, for example, a quantized transform coefficient. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reconstruct a residual block for the block. However, in the case where the video encoder 200 does not apply transform and / or quantization, the video decoder 300 may bypass the inverse quantization and / or inverse transform steps. For example, the decoded value may be a residual value that does not require inverse quantization and / or inverse transform. The video decoder 300 uses the signaled prediction mode (intra-frame prediction or inter-frame prediction) and related prediction information (e.g., motion information for inter-frame prediction) 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 reconstruct 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.

[0073] According to the techniques of the present disclosure, the video encoder 200 and the video decoder 300 may be configured to use different decoding schemes for transform skipped blocks (i.e., blocks decoded in the case of transform skipping). For example, it may be desirable to support lossless decoding in VVC without adding lossless specific tools. There may be at least two residual decoding schemes. The first residual decoding scheme is referred to as transform coefficient coding (TRCC), and the second residual decoding scheme is referred to as transform skip (TS) residual decoding (TSRC).

[0074] The TRCC scheme and the TSRC scheme may be different ways of representing residual values. In both TRCC and TSRC, the video encoder 200 may determine whether the residual value in the residual block is valid (e.g., the absolute value is greater than 0), and determine whether the residual value is greater than a threshold value. For example, the video encoder 200 may determine whether the residual value in the residual block is greater than 1, greater than 3, greater than 5, and the like. The video encoder 200 may signal a plurality of flags that the video decoder 300 uses to determine the residual value. For example, if the video encoder 200 signals a first flag indicating that the residual value is valid and a second flag indicating that the residual value is greater than 1, but there is no third flag indicating that the residual value is less than 2, the video decoder 300 may determine that the residual value is greater than 1 and less than 2.

[0075] However, there may be a difference between the TRCC scheme and the TSRC scheme. In TRCC, the video encoder 200 may signal information indicating the position of the last significant coefficient value, which the video decoder 300 may use to determine that all values ​​after the position of the last significant value are 0. However, in the TSRC scheme, in the case of skipping the transform, there may be no last significant value because there may be a significant value at any position within the residual block, including the last position in the residual block.

[0076] As another example, the number of flags indicating whether a residual value among a plurality of residual values ​​is greater than a threshold value in the TRCC scheme is different from the number of flags indicating whether a residual value among a plurality of residual values ​​is greater than a threshold value in the TSRC scheme. For example, the TRCC scheme may include a flag indicating whether a residual value is greater than 3, but not a flag indicating whether a residual value is greater than 5. However, in the TSRC scheme, there may be a flag indicating whether a residual value is greater than 5, a flag indicating whether a residual value is greater than 7, and a flag indicating whether a residual value is greater than 9.

[0077] As another example, in the TRCC scheme, the scanning order of the residual block may be from the last to the first, that is, from the last residual value to the first residual value. However, in the TSRC scheme, the scanning order of the residual block may be from the first residual value to the last residual value.

[0078] Therefore, the TRCC scheme and the TSRC scheme are different types of coding schemes applied to residual values. As described in more detail, in some examples, the video encoder 200 uses the TSRC scheme for all blocks decoded in the case of transform skipping, and the TRCC scheme is not applicable to the blocks decoded in the case of transform skipping. However, it may be beneficial to allow the TRCC scheme to be used for blocks decoded in the case of transform skipping.

[0079] In such cases, the video encoder 200 may signal the video decoder 300 to receive information indicating whether the first type of coding scheme (e.g., TRCC scheme) or the second type of coding scheme (e.g., TSRC scheme) is applied. Such signaling may only exist in the case of enabling transform skip. For example, the video decoder 300 may first determine whether transform skip is enabled, and parse the flag in the slice header indicating whether the first type of coding scheme or the second type of coding scheme is applied based on enabling transform skip. That is, if transform skip is enabled, the video decoder 300 may parse the flag in the slice header indicating whether the first type of coding scheme or the second type of coding scheme is applied. However, if transform skip is not enabled, the video decoder 300 may not parse the flag in the slice header indicating whether the first type of coding scheme or the second type of coding scheme is applied.

[0080] Lossless decoding may require skipping a transform operation (e.g., the video encoder 200 bypasses transforming the residual values ​​to the frequency domain with coefficient values, and the video decoder 300 bypasses the inverse transform operation because the residual values ​​are already in the sample domain). In some examples, the video encoder 200 may signal a TS decoding flag that indicates that the transform is skipped for a block (e.g., for a transform skipped block). The TS decoding flag may be signaled as part of a multiple transform selection (MTS) index. In some examples, if a block-based quantized residual domain delta pulse code modulation (BDPCM) mode is selected, the video decoder 300 may implicitly determine that the block is a transform skipped block (e.g., a block decoded with a transform skipped block) instead of explicitly signaling the TS decoding flag. In some examples, the video encoder 200 and the video decoder 300 may utilize TSRC as a residual decoding scheme for transform skipped blocks.

[0081] In some examples, it may be desirable to use TRCC as well as BDPCM for transform skip blocks. If existing low-level signaling is to be used, a flag in the SPS, PPS, picture header, or slice header may be used to indicate the residual coding technique to be used when skipping the transform. That is, the video encoder 200 may signal and the video decoder 300 may receive a flag in the slice header indicating whether a first type of coding scheme (e.g., TRCC) or a second type of coding scheme (e.g., TSRC) is applied to the residual value of the block decoded in the case of a transform skip. In this way, it may not be necessary to change the TS decoding path of VVC Draft 6 (e.g., where the transform is bypassed), and TSRC or TRCC may be used. However, even in the case of changes to the TS decoding path, the techniques described in the present disclosure may be used.

[0082] This disclosure describes techniques for adding one or more syntax elements (e.g., flags) in an SPS, PPS, picture header, or slice header to select a coefficient (residual) coding technique (e.g., TRCC or TSRC) to be used when a transform is skipped. The one or more syntax elements (e.g., flags) may indicate whether TSRC or TRCC is used for a TS block (e.g., a block decoded in the case of a transform skip). In some examples, the signaling method may take effect only if the quantization parameter (QP) of the transform skipped block is less than or equal to 4 (i.e., lossless).

[0083] For example, VVC draft 10 includes sh_ts_residual_coding_disabled_flag. sh_ts_residual_coding_disabled_flag is signaled in the slice header and is an example of a flag described in the present disclosure to indicate whether TSRC or TRCC is used for blocks decoded in the case of transform skipping. For example, if sh_ts_residual_coding_disabled_flag is true (e.g., logical 1), it means that TSRC is disabled and TRCC is used. If sh_ts_residual_coding_disabled_flag is false (e.g., logical 0), it means that TSRC is not disabled and TSRC is used instead of TRCC.

[0084] VVC draft 10 defines sh_ts_residual_coding_disabled_flag as follows: sh_ts_residual_coding_disabled_flag equal to 1 specifies that the residual_coding() syntax structure is used to parse residual samples of transform skip blocks for the current slice. sh_ts_residual_coding_disabled_flag equal to 0 specifies that the residual_ts_coding() syntax structure is used to parse residual samples of transform skip blocks for the current slice. When sh_ts_residual_coding_disabled_flag is not present, it is inferred to be equal to 0. In VVC draft 10, the residual_coding() syntax structure refers to the TRCC scheme, while the residual_ts_coding() syntax structure refers to the TSRC scheme.

[0085] As described in Section 7.3.7 (Slice Header Syntax) of VVC Draft 10, the sh_ts_residual_coding_disabled_flag syntax element is signaled only when transform skipping is enabled. For example, in VVC Draft 10, the video encoder 200 may signal sps_transform_skip_enabled_flag indicating whether transform skipping is enabled for a block. The video decoder 300 may receive sps_transform_skip_enabled_flag and parse sh_ts_residual_coding_disabled_flag only when sps_transform_skip_enabled_flag is true (e.g., only when transform skipping is enabled).

[0086] Thus, in one or more examples, the video decoder 300 may receive one or more syntax elements (e.g., sh_ts_residual_coding_disabled_flag) of video data from a video bitstream, the one or more syntax elements indicating whether a first type of coding scheme (e.g., TRCC) or a second type of coding scheme (e.g., TSRC) is applied to a residual value of a block decoded in a transform skip. The residual value indicates the difference between the block and the predicted block, and in a transform skip, the residual value is not transformed from the sample domain to the frequency domain (e.g., a DCT operation or a DST operation is skipped). In some examples, the video decoder 300 may receive the sh_ts_residual_coding_disabled_flag in a slice header.

[0087] In one or more examples, the video decoder 300 may receive a first flag (e.g., sps_transform_skip_enabled_flag) indicating whether transform skipping is enabled. To receive one or more syntax elements, the video decoder 300 may parse a second flag (e.g., sh_ts_residual_coding_disabled_flag) in the slice header based on the first flag indicating that transform skipping is enabled, the second flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied. For example, if the first flag (e.g., sps_transform_skip_enabled_flag) is true, the video decoder 300 may only parse the second flag (e.g., sh_ts_residual_coding_disabled_flag). If the first flag is false, the video decoder 300 may not parse the second flag.

[0088] The video decoder 300 may determine a type of coding scheme to apply to the residual value based on one or more syntax elements. For example, if sh_ts_residual_coding_disabled_flag is true, the video decoder 300 may determine to use TRCC, and if sh_ts_residual_coding_disabled_flag is false, determine to use TSRC.

[0089] The video decoder 300 may determine the residual value based on the determined type of decoding scheme. Because the block is decoded in a transform skip, the video decoder 300 may determine the residual value without applying an inverse transform to the residual value. For example, the residual value is already in the sample domain, and therefore an inverse transform from the frequency domain to the sample domain may not be required.

[0090] The video decoder 300 may reconstruct the block based on the determined residual value and the prediction block. For example, the video decoder 300 may add the prediction block to the determined residual value to reconstruct the block.

[0091] In one or more examples, the video encoder 200 may determine the residual value based on the difference between the block to be coded and the predicted block in case of transform skipping.As described above, in transform skipping, the residual value is not transformed from the sample domain to the frequency domain.

[0092] The video encoder 200 may determine a type of decoding scheme between a first type of decoding scheme (e.g., TRCC) and a second type of decoding scheme (e.g., TSRC) to apply to the residual value. The video encoder 200 may encode the residual value based on the determined type of decoding scheme, and send one or more syntax elements of the video data (e.g., sh_ts_residual_coding_disabled_flag in a slice header) to the video bitstream with a signal, the one or more syntax elements indicating whether the first type of decoding scheme (e.g., TRCC) or the second type of decoding scheme (e.g., TSRC) is applied to the residual value.

[0093] In some examples, TSRC can be replaced with a TRCC scheme that skips the decoding of the last non-zero position (i.e., the position of the last significant coefficient) (assuming that the last non-zero coefficient position in the block is the last position of the block). In addition, the video encoder 200 and the video decoder 300 can rotate (e.g., 180 degrees) the coefficients to be decoded in (HEVC Rext). In such an example, it may not be necessary to signal the decoding scheme to be used for the transform skip case. For example, existing signaling can be used to achieve lossless decoding because the transform skip path will use the TRCC scheme without signaling the last position and possibly rotating the block to be decoded.

[0094] The present disclosure may generally involve "signaling" certain information (such as syntax elements). The term "signaling" may generally refer to 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. Generally, signaling refers to generating values ​​in a bitstream. As described above, the source device 102 may transmit the bitstream to the destination device 116 in substantially real time or not in real time (e.g., as may occur when storing syntax elements to the storage device 112 for later retrieval by the destination device 116).

[0095] Figure 2A and Figure 2B1 is a conceptual diagram showing an example quadtree binary tree (QTBT) structure 130 and a corresponding coding tree unit (CTU) 132. Solid lines represent quadtree splits, while 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 horizontal splitting and 1 indicates vertical splitting. For quadtree splitting, because the quadtree node splits a block horizontally and vertically into 4 sub-blocks of equal size, there is no need to indicate the split type. Therefore, the video encoder 200 can encode the following, and the video decoder 300 can decode the following: syntax elements (such as split information) for the regional tree level (i.e., solid line) of the QTBT structure 130, and syntax elements (such as split information) for the prediction tree level (i.e., dashed line) of the QTBT structure 130. The video encoder 200 may encode video data (such as prediction and transform data) for a CU represented by a terminal leaf node of the QTBT structure 130 , and the video decoder 300 may decode the video data.

[0096] generally, Figure 2B The CTU 132 may be associated with parameters defining the size of blocks corresponding to nodes at the first and second levels of the QTBT structure 130. These parameters may include a CTU size (indicating the size of the CTU 132 in samples), a minimum quadtree size (MinQTSize, which indicates the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, which indicates the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, which indicates the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, which indicates the minimum allowed binary tree leaf node size).

[0097] 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 of 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 node of the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node may be further segmented by the corresponding binary tree. The binary tree splitting of a node may be iterated until the node generated from 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 called a coding 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".

[0098] In one example of a QTBT partitioning structure, the CTU size is set to 128×128 (luminance sample and two corresponding 64×64 chrominance samples), MinQTSize is set to 16×16, MaxBTSize is set to 64×64, 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 16×16 (i.e., MinQTSize) to 128×128 (i.e., CTU size). If the leaf quadtree node is 128×128, because the size exceeds MaxBTSize (i.e., 64×64 in this example), the leaf quadtree node will not be further split by the binary tree. Otherwise, the leaf quadtree node will be further split by the binary tree. Therefore, the quadtree leaf node is also the root node for the binary tree and has a binary tree depth of 0. When the binary tree depth reaches MaxBTDepth (4 in this example), no further splitting is allowed. When a binary tree node has a width equal to MinBTSize (4 in this example), it means that no further horizontal splitting is allowed. Similarly, a binary tree node with a height equal to MinBTSize means that no further vertical 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.

[0099] 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 to limit the techniques generally exemplified and described in this disclosure. For the purpose of explanation, this disclosure describes the video encoder 200 in the context of video coding standards such as the H.265 video coding standard (also known as HEVC) and the H.266 video coding standard (also known as VVC). However, the techniques of this disclosure are not limited to these video coding standards and are generally applicable to video encoding and decoding.

[0100] exist Figure 3 In the example of , the video encoder 200 includes 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. Any one 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 can be implemented in one or more processors or in processing circuits. For example, the units of the video encoder 200 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 encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.

[0101] The video data memory 230 may store video data to be encoded by the components of the video encoder 200. The video encoder 200 may receive video data from, for example, the video source 104 ( Figure 1 ) receives the video data stored in the video data memory 230. DPB 218 can act as a reference picture memory, which stores reference video data for use when subsequent video data is predicted by the video encoder 200. Video data memory 230 and DPB 218 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 chip with other components of the video encoder 200 (as shown), or off chip relative to those components.

[0102] 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 specifically described as such), or to memory external to the video encoder 200 (unless specifically 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 for outputs from the various units of the video encoder 200 .

[0103] Shows Figure 3 The various units of the video encoder 200 are described to help understand the operations performed by the video encoder 200. These units can be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide specific functions and are pre-set with respect to the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions with the operations that can be performed. 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 (e.g., to receive parameters or output parameters), but the types of operations performed by fixed-function circuits are generally immutable. In some examples, one or more of the units may be different circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0104] 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 in which 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 that the video encoder 200 receives and executes, or another memory (not shown) within the video encoder 200 may store such instructions.

[0105] The video data memory 230 is configured to store the received video data. The video encoder 200 may retrieve pictures 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 original video data to be encoded.

[0106] 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 that 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.

[0107] The mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and the 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.

[0108] 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 in a slice. The mode selection unit 202 may partition the CTUs of the picture according to a tree structure (such as 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. Such CUs may also be generally referred to as "video blocks" or "blocks".

[0109] 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 the overlapping portion of the PU and TU in HEVC). In order to inter-predict the current block, the motion estimation unit 222 may 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 decoded pictures stored in the DPB 218). Specifically, the motion estimation unit 222 may calculate a value representing how similar the potential reference block will be 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 may typically perform these calculations using sample-by-sample differences between the current block and the reference block under consideration. The motion estimation unit 222 may identify the reference block with the lowest value resulting from these calculations, which indicates the reference block that most closely matches the current block.

[0110] The motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of the reference block in the reference picture relative to the position of the current block in the 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 the 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.

[0111] As another example, for intra prediction or intra prediction decoding, the intra prediction unit 226 can generate a prediction block based on 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 fill these calculated values ​​across the current block in a defined direction to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average value of adjacent samples of the current block and generate a prediction block to include the obtained average value for each sample of the prediction block.

[0112] 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 can generate the residual block using residual differential pulse coding modulation (RDPCM) by calculating the difference between the sample values ​​in the residual block. In some examples, the residual generation unit 204 can be formed using one or more subtractor circuits that perform binary subtraction.

[0113] In an 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 noted above, the size of a CU may refer to the size of a luma coding block of the CU, and the size of a PU may refer to the size of a luma prediction unit of the PU. Assuming that the size of a particular CU is 2N×2N, the video encoder 200 may support PU sizes of 2N×2N or N×N for intra-prediction, and symmetric PU sizes of 2N×2N, 2N×N, N×2N, N×N, or the like for inter-prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning for PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter-prediction.

[0114] In an example where the mode selection unit does not further partition a CU into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder 200 and the video decoder 300 may support a CU size of 2N×2N, 2N×N, or N×2N.

[0115] For other video coding techniques (such as intra-block copy mode coding, affine mode coding, and linear model (LM) mode coding, to name a few 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.

[0116] 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 a sample-by-sample difference between the prediction block and the current block.

[0117] 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 (e.g., a rotation transform). In some examples, the transform processing unit 206 does not apply a transform to the residual block.

[0118] 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 QP value associated with the current block. Video encoder 200 (e.g., via mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may cause a loss of information, and therefore, the quantized transform coefficients may have a lower precision than the original transform coefficients produced by transform processing unit 206.

[0119] like Figure 3 As shown in dashed lines in FIG. 2 , in some examples, one or both of the transform processing unit 206 and the quantization unit 208 may be bypassed. For example, the mode selection unit 202 may determine that the block is to be encoded in a transform skip mode. For a transform skip block, operations for the transform processing unit 206 may be bypassed, and operations for the quantization unit 208 may be bypassed.

[0120] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct the residual block from the transform coefficient block. In examples where one or more transforms and quantizations are skipped, the operations of the inverse quantization unit 210 and the inverse transform processing unit 212 may be similarly skipped, as indicated by the dashed lines.

[0121] The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (although potentially with some degree of distortion) based on the reconstructed residual block and the prediction 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 from the prediction block generated by the mode selection unit 202 to generate a reconstructed block.

[0122] 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.

[0123] 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 estimation unit 222 and the motion compensation unit 224 can retrieve a reference picture formed by the reconstructed (and potentially filtered) blocks from the DPB 218 to perform inter-frame prediction on blocks of subsequently encoded pictures. In addition, the intra-frame prediction unit 226 can use the reconstructed blocks of the current picture in the DPB 218 to perform intra-frame prediction on other blocks in the current picture.

[0124] 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.

[0125] In some examples, in the case of performing a transform, the entropy coding unit 220 can be configured to use a first coding scheme called transform coefficient coding (TRCC). In the case of skipping the transform, the entropy coding unit 220 can be configured to use a second coding scheme called transform skip residual coding (TSRC). However, in the examples described in the present disclosure, TRCC is sometimes used even for transform skip blocks (e.g., where the transform is skipped).

[0126] There may be various differences between TRCC and TSRC. For example, in the TRCC scheme, information indicating the position of the last valid value is sent by a signal. In the TSRC scheme, information indicating the position of the last valid value is not sent by a signal. The number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TRCC scheme (e.g., greater than 1 flag, greater than 3 flags, etc.) is different from the number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TSRC scheme. For another example, the scanning order for residual blocks in TRCC and TSRC may be different (e.g., TRCC is the last to first residual value scanning order, while TSRC is the first to last residual value scanning order).

[0127] The residual generation unit 204 may determine residual information (e.g., residual values) based on the difference between the block to be decoded and the predicted block in the case of transform skipping. The mode selection unit 202 may determine the type of decoding scheme to be applied to the residual information (e.g., the type of decoding scheme is one of TRCC or TSRC). The entropy coding unit 220 may encode the residual information based on the determined type of decoding scheme. The entropy coding unit 220 may also signal one or more syntax elements (e.g., sh_ts_residual_coding_disabled_flag) indicating the type of decoding scheme into the video bitstream. In some examples, the entropy coding unit 220 may signal one or more syntax elements based on the quantization parameter (QP) of the quantization unit 208 being less than or equal to a threshold value (e.g., 4).

[0128] As another example, the residual generation unit 204 may determine the residual information based on the difference between the block to be decoded and the predicted block in the case of a transform skip. The entropy coding unit 220 may encode the residual information based on a TRCC scheme in which the last non-zero position is skipped for decoding. The entropy coding unit 220 may signal the encoded residual information. In some examples, the entropy coding unit 220 may perform its operation on a rotated version of the residual information. Furthermore, in some examples, the entropy coding unit 220 may avoid signaling (e.g., not signaling) information using the TRCC scheme.

[0129] Although the above example techniques are described with respect to entropy coding unit 220, the example techniques should not be considered so limited. In some examples, mode selection unit 202, or a combination of entropy coding unit 220 and mode selection unit 202, can be configured to perform the example techniques. Furthermore, in some examples, various combinations of units of video encoder 200 can be configured to perform the example techniques. In general, video encoder 200 can be configured to perform the example techniques described in this disclosure.

[0130] The video encoder 200 may output a bitstream including entropy-encoded syntax elements required for reconstructing a block of a slice or picture. Specifically, the entropy encoding unit 220 may output a bitstream.

[0131] The above operations are described with respect to blocks. Such descriptions should be understood as operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding blocks and chroma coding blocks are the luma components and chroma components of a CU. In some examples, the luma coding blocks and chroma coding blocks are the luma components and chroma components of a PU.

[0132] In some examples, operations performed with respect to luma coding blocks need not be repeated for chroma coding blocks. As an example, operations for identifying motion vectors (MVs) and reference pictures for luma coding blocks need not be repeated to identify MVs and reference pictures for chroma blocks. Specifically, the MVs for luma coding blocks may be scaled to determine MVs for chroma blocks, and the reference pictures may be the same. As another example, the intra prediction process may be the same for luma coding blocks and chroma coding blocks.

[0133] 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 does not limit the techniques generally illustrated and described in this disclosure. For the purpose of explanation, this disclosure describes the video decoder 300 according to the techniques of VVC and HEVC. However, the techniques of this disclosure can be performed by a video decoding device configured for other video decoding standards.

[0134] 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 134 can be implemented in one or more processors or in 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.

[0135] The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include additional units that perform predictions 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.

[0136] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of video decoder 300. For example, the video bitstream may be obtained 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. In addition, CPB memory 320 may store video data other than syntax elements of 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 decoded pictures, 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 memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or a separate memory device. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip relative to those components.

[0137] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) retrieves the decoded video data. That is, memory 120 may utilize CPB memory 320 to store data as discussed above. Likewise, when some or all of the functionality of video decoder 300 is implemented in software to be executed by processing circuitry of video decoder 300, memory 120 may store instructions to be executed by video decoder 300.

[0138] Shows Figure 4 The various units shown in FIG. 3 are used to help understand 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 pre-set with respect to the operations that can be performed. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions with respect to the operations that can be performed. 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 (e.g., to receive parameters or output parameters), but the types of operations performed by fixed-function circuits are 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.

[0139] 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 the 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.

[0140] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode the video data to reconstruct 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.

[0141] Generally, the video decoder 300 reconstructs a picture block by block. The video decoder 300 may perform a reconstruction operation on each block individually (wherein a block currently being reconstructed (ie, decoded) may be referred to as a "current block").

[0142] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of the quantized transform coefficient block and transform information such as a quantization parameter (QP) and / or a transform mode indication. 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 for 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.

[0143] After the inverse quantization unit 306 forms the transform coefficient block, the 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, the 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.

[0144] like Figure 4 As shown in dashed lines in FIG. 3 , in some examples, one or both of inverse quantization unit 306 and inverse transform processing unit 308 may be bypassed. For example, prediction processing unit 304 may receive information that a block is coded in transform skip mode. Prediction processing unit 304 may then cause operations for inverse transform processing unit 308 to be bypassed, and in some examples, bypass operations for inverse quantization unit 306.

[0145] In one or more examples, the prediction processing unit 304 may receive one or more syntax elements (e.g., sh_ts_residual_coding_disabled_flag in a slice header), which indicate the type of decoding scheme applied to the residual information of the block decoded in the case of transform skipping (e.g., the type of decoding scheme may be one of the TRCC scheme or the TSRC scheme). As described above, there may be various differences between TRCC and TSRC. For example, in the TRCC scheme, information indicating the position of the last valid value is parsed. In the TSRC scheme, information indicating the position of the last valid value is not parsed. The number of flags indicating whether the residual value in a plurality of residual values ​​is greater than a threshold in the TRCC scheme (e.g., greater than 1 flag, greater than 3 flags, etc.) is different from the number of flags indicating whether the residual value in a plurality of residual values ​​is greater than a threshold in the TSRC scheme. For another example, the scanning order for the residual block in TRCC and TSRC may be different (e.g., TRCC is the last to first residual value scanning order, while TSRC is the first to last residual value scanning order).

[0146] The residual value indicates the difference between the block and the predicted block. Prediction processing unit 304 may determine the residual value based on the type of decoding scheme. In some examples, prediction processing unit 304 may receive one or more syntax elements based on a quantization parameter (QP) less than or equal to a threshold value (e.g., 4).

[0147] As another example, prediction processing unit 304 may determine residual information for a block decoded with a transform skip, wherein determining the residual information includes determining the residual information using a transform coefficient decoding (TRCC) scheme in which decoding of the last non-zero position is skipped. In some examples, prediction processing unit 304 may rotate the determined residual information before reconstructing the block. Prediction processing unit 304 may determine the residual information using a TRCC scheme without receiving information that the TRCC scheme is to be used.

[0148] Although the above example techniques are described with respect to prediction processing unit 304, the example techniques should not be considered so limited. In some examples, entropy decoding unit 302, or a combination of entropy decoding unit 302 and prediction processing unit 304, can be configured to perform the example techniques. Furthermore, in some examples, various combinations of units of video decoder 300 can be configured to perform the example techniques. In general, video decoder 300 can be configured to perform the example techniques described in this disclosure.

[0149] In addition, prediction processing unit 304 generates a prediction block based on the prediction information syntax element entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, motion compensation unit 316 can generate a prediction block. In this case, the prediction information syntax element can indicate a reference picture in DPB 314 from which to retrieve the reference block, 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 can generally generate a prediction block in the same manner as described with respect to motion compensation unit 224 ( Figure 3 )The inter-frame prediction process is performed in a manner substantially similar to that described in detail above.

[0150] As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate a prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, the intra-prediction unit 318 may generally generate a prediction block in the same manner as described with respect to the intra-prediction unit 226 ( Figure 3 The intra prediction process is performed in a manner substantially similar to that described in the foregoing description. The intra prediction unit 318 may retrieve data of neighboring samples of the current block from the DPB 314.

[0151] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may reconstruct the current block by adding samples of the residual block to corresponding samples of the prediction block.

[0152] 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 may not necessarily be performed in all examples.

[0153] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in an example 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 an example 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 discussed above, the DPB 314 may provide reference information (such as samples of the current picture for intra-frame prediction and previously decoded pictures for subsequent motion compensation) to the prediction processing unit 304. In addition, the video decoder 300 may output a decoded picture (e.g., a decoded video) from the DPB 314 for use in, for example, Figure 1 The reconstructed block may be subsequently presented on a display device such as the display device 118 of the display device 118. For example, the display device 118 may display a picture including the reconstructed block.

[0154] Figure 5 2 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although the processing circuit ( 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.

[0155] The processing circuitry of video encoder 200 may determine a residual value based on the difference between the block to be decoded and the predicted block in the case of transform skipping (350). In transform skipping, the residual value is not transformed from the sample domain to the frequency domain. For example, the operation of transform processing unit 206 may be bypassed.

[0156] Processing circuitry of video encoder 200 may determine a type of decoding scheme between a first type of decoding scheme and a second type of decoding scheme to be applied to the residual value (352). In one example, the first type of decoding scheme is a transform coefficient coding (TRCC) scheme and the second type of decoding scheme is a transform skip residual coding (TSRC) scheme. Video encoder 200 may determine the type of decoding scheme based on a rate-distortion analysis indicating which coding scheme provides good video quality balanced with video compression.

[0157] In the TRCC scheme, information indicating the position of the last valid value is sent by a signal, but in the TSRC scheme, information indicating the position of the last valid value is not sent by a signal. The number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TRCC scheme (e.g., greater than 1 flag, greater than 3 flags, etc.) is different from the number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TSRC scheme. The scanning order for residual blocks in TRCC and TSRC may be different (e.g., TRCC is the last to first residual value scanning order, while TSRC is the first to last residual value scanning order). The above are some example methods in which TRCC and TSRC are different decoding schemes, and the example methods should not be considered to be exhaustive or required in all cases.

[0158] The processing circuitry of video encoder 200 may encode the residual value based on the determined type of coding scheme (354). For example, if TSRC is the determined type of coding scheme, the processing circuitry may not signal the position of the last significant value, may signal a greater than threshold flag according to TSRC, and may scan from beginning to end. If TRCC is the determined type of coding scheme, the processing circuitry may signal the position of the last significant value, may signal a greater than threshold flag according to TRCC, and may scan from end to beginning.

[0159] The processing circuitry of the video encoder 200 may signal one or more syntax elements into the video bitstream, the one or more syntax elements indicating whether the first type of coding scheme or the second type of coding scheme is applied to the residual values ​​(356). For example, the processing circuitry may signal sh_ts_residual_coding_disabled_flag in the slice header to indicate whether the TRCC or TSRC scheme is applied to the residual values.

[0160] Figure 6 1 is a flowchart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although the processing circuit ( 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 processing circuit of the video decoder 300 may receive one or more syntax elements of video data from a video bitstream, the one or more syntax elements indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a residual value of a block decoded in the case of a transform skip (370). The residual value indicates the difference between the block and the predicted block, and in the transform skip, the residual value is not transformed from the sample domain to the frequency domain. That is, the residual value is already in the sample domain.

[0162] As an example, to receive one or more syntax elements, the processing circuitry of the video decoder 300 may receive a flag (e.g., sh_ts_residual_coding_disabled_flag) in a slice header, the flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to residual values ​​of a block decoded with transform skipping. In some examples, the processing circuitry of the video decoder 300 may receive a first flag (e.g., sps_transform_skip_enabled_flag) indicating whether transform skipping is enabled. To receive one or more syntax elements, the processing circuitry of the video decoder 300 may parse a second flag (e.g., sh_ts_residual_coding_disabled_flag) in a slice header based on the first flag indicating that transform skipping is enabled, the second flag indicating whether the first type of decoding scheme or the second type of decoding scheme is applied.

[0163] In some examples, the first type of decoding scheme is a transform coefficient coding (TRCC) scheme, and the second type of decoding scheme is a transform skip residual coding (TSRC) scheme. In the TRCC scheme, information indicating the position of the last significant value is parsed, but in the TSRC scheme, information indicating the position of the last significant value is not parsed. The number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TRCC scheme (e.g., greater than 1 flag, greater than 3 flags, etc.) is different from the number of flags indicating whether a residual value among multiple residual values ​​is greater than a threshold in the TSRC scheme. The scanning order for residual blocks in TRCC and TSRC may be different (e.g., TRCC is a last to first residual value scanning order, while TSRC is a first to last residual value scanning order).

[0164] The processing circuitry of the video decoder 300 may determine the type of coding scheme to be applied to the residual value based on the one or more syntax elements (372). For example, if sh_ts_residual_coding_disabled_flag is true, the processing circuitry of the video decoder 300 may determine that TRCC is enabled. If sh_ts_residual_coding_disabled_flag is false, the processing circuitry of the video decoder 300 may determine that TSRC is enabled.

[0165] The processing circuitry of the video decoder 300 may determine the residual value based on the determined type of decoding scheme (374). For example, if TSRC is the determined type of decoding scheme, the processing circuitry may not parse the position of the last significant value, may parse a threshold flag greater than according to TSRC, and may scan from beginning to end. If TRCC is the determined type of decoding scheme, the processing circuitry may parse the position of the last significant value, may parse a threshold flag greater than according to TRCC, and may scan from end to end. In addition, because the block is decoded in a transform skip, to determine the residual value, the processing circuitry of the video decoder 300 may determine the residual value without applying an inverse transform to the residual value.

[0166] The processing circuitry of video decoder 300 may reconstruct the block based on the determined residual value and the prediction block (376). The processing circuitry of video decoder 300 may add the residual value to the prediction block to reconstruct the block.

[0167] The following are one or more example techniques that may be performed alone or in combination.

[0168] Example 1. A method for decoding video data, the method comprising: receiving one or more syntax elements, the one or more syntax elements indicating a type of decoding scheme applied to residual information of a block decoded in a transform skipping case, wherein the residual information indicates a difference between the block and a prediction block, determining the residual information based on the type of decoding scheme, and reconstructing the block based on the determined residual information and the prediction block.

[0169] Example 2. A method for encoding video data, the method comprising: determining residual information based on the difference between a block decoded and a predicted block in a case of transform skipping, determining a type of decoding scheme to be applied to the residual information, encoding the residual information based on the determined type of decoding scheme, and sending one or more syntax elements indicating the type of decoding scheme by signaling.

[0170] Example 3. A method according to any one of Examples 1 and 2, wherein the type of decoding scheme includes one of a transform coefficient coding (TRCC) scheme or a transform skip residual coding (TSRC).

[0171] Example 4. A method according to any one of Examples 1-3, wherein determining the residual information includes: determining the residual information without applying a transformation or an inverse transformation to the residual information.

[0172] Example 5. A method according to any one of Examples 1, 3 and 4, wherein receiving the one or more syntax elements includes: receiving the one or more syntax elements based on a quantization parameter (QP) being less than or equal to a threshold.

[0173] Example 6. A method according to any one of Examples 2-4, wherein signaling one or more syntax elements indicating the type of decoding scheme includes: signaling the one or more syntax elements based on a quantization parameter (QP) being less than or equal to a threshold.

[0174] Example 7. A method according to any one of Examples 5 and 6, wherein the threshold is 4.

[0175] Example 8. A method for decoding video data, the method comprising: determining residual information of a block decoded in a transform skipping case, wherein determining the residual information comprises: determining the residual information using a transform coefficient coding (TRCC) scheme in which decoding of the last non-zero position is skipped, and wherein the residual information indicates the difference between the block and a prediction block, and reconstructing the block based on the residual information and the prediction block.

[0176] Example 9. A method for encoding video data, the method comprising: determining residual information for a block decoded with a transform skip, wherein the residual information indicates a difference between the block and a predicted block, encoding the residual information based on a transform coefficient coding (TRCC) scheme in which decoding of the last non-zero position is skipped, and sending the decoded residual information with a signal.

[0177] Example 10. The method according to Example 9 further includes: rotating the determined residual information before reconstructing the block.

[0178] Example 11. The method according to Example 9 also includes: rotating the residual information before encoding the residual information.

[0179] Example 12. A method according to any one of Examples 8 and 9, wherein rotating includes: rotating 180 degrees.

[0180] Example 13. A method according to any one of Examples 8, 10 and 12, wherein determining the residual information using the TRCC scheme includes: determining the residual information using the TRCC scheme without receiving information that the TRCC scheme is to be used.

[0181] Example 14. The method of any one of Examples 9, 11, and 12, further comprising: avoiding signaling information using the TRCC scheme.

[0182] Example 15. A method comprising any one or a combination of Examples 1, 3-5, 7, 8, 10, 12, and 13.

[0183] Example 16. A method comprising any one or a combination of Examples 2-4, 6, 7, 9, 11, 12, and 14.

[0184] Example 17. A device for decoding video data, the device comprising: a memory configured to store the video data, and a processing circuit configured to perform the method according to Example 15.

[0185] Example 18. A device for encoding video data, the device comprising: a memory configured to store the video data, and a processing circuit configured to perform the method according to Example 16.

[0186] Example 19. The device of any one of Examples 17 and 18, further comprising: a display configured to display the decoded video data.

[0187] Example 20. A device according to any of Examples 17-19, wherein the device includes one or more of the following: a camera, a computer, a mobile device, a broadcast receiver device, a set-top box, or a wireless communication device.

[0188] Example 21. An apparatus according to any one of Examples 17, 19 and 20, wherein the processing circuit includes a video decoder.

[0189] Example 22. An apparatus according to any of Examples 18-20, wherein the processing circuit comprises a video encoder.

[0190] Example 23. A computer-readable storage medium having instructions stored thereon, which when executed cause one or more processors to perform the method of any of Examples 15 or 16.

[0191] Example 24. An apparatus for decoding video data, the apparatus comprising means for performing the method of any of Examples 15 or 16.

[0192] It is to be appreciated that, depending on the examples, certain actions or events of any of the techniques described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary to implement the techniques). In addition, in some examples, actions or events may be performed concurrently rather than sequentially, such as through multithreading, interrupt handling, or multiple processors.

[0193] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted through a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium such as a data storage medium or a communication medium, the communication medium including, for example, any medium that facilitates the transfer of a computer program from one place to another 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 obtain 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.

[0194] By way of example and not 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 desired program codes in the form of instructions or data structures and can be accessed by a computer. In addition, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology (e.g., infrared, radio and microwave), coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (e.g., infrared, radio and microwave) are 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 are instead directed to non-temporary tangible storage media. As used herein, disks and optical disks include compact disks (CDs), laser optical disks, optical disks, digital versatile disks (DVDs), floppy disks and blue-ray disks, wherein disks usually copy data magnetically, while optical disks use lasers to optically copy data. Combinations of the above should also be included within the scope of computer-readable media.

[0195] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the terms "processor" and "processing circuitry" as used herein may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. In addition, in some aspects, the functionality 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 implemented entirely in one or more circuits or logic elements.

[0196] The techniques of the present disclosure may be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in the present disclosure to emphasize the functional aspects of a device configured to perform the disclosed techniques, but do not necessarily need to be implemented by different hardware units. Specifically, 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.

[0197] 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 comprising: receiving a first flag from a video bitstream indicating whether transform skipping is enabled; receiving, based on the first flag indicating that transform skipping is enabled, a second flag in a slice header of a slice of the video data from the video bitstream, the second flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a plurality of residual values ​​of a block of the slice of the video data decoded with transform skipping, wherein, according to the first type of decoding scheme, information indicating a position of a last significant value is signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping, and wherein, according to the second type of decoding scheme, information indicating the position of the last significant value is not signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping; Based on the second flag, determining a type of decoding scheme between the first type of decoding scheme and the second type of decoding scheme; Based on the first flag, determining that the block of the video data is decoded with transform skipping; Determining a plurality of residual values ​​of the block decoded in the case of transform skipping based on the determined type of decoding scheme, comprising: parsing the information indicating the position of the last valid value of the plurality of residual values ​​of the block from the video bitstream only if the first type of decoding scheme is determined, wherein the plurality of residual values ​​indicate the difference between the block and a predicted block; and The block is reconstructed based on the determined plurality of residual values ​​and the prediction block, wherein the determined plurality of residual values ​​are not transformed from the sample domain to the frequency domain when the reconstruction is performed according to transform skipping.

2. The method according to claim 1, wherein: The first type of decoding scheme is a transform coefficient decoding TRCC scheme, and the second type of decoding scheme is a transform skip residual decoding TSRC scheme, wherein the first type of decoding scheme and the second type of decoding scheme include: decoding a significance map of the block.

3. The method according to claim 2, wherein: The number of flags indicating whether a residual value among the multiple residual values ​​is greater than a threshold in the TRCC scheme is a first value, wherein, in the TSRC scheme, the number of flags indicating whether the residual value among the multiple residual values ​​is greater than the threshold is a second value, and wherein the first value is different from the second value.

4. The method according to claim 1, wherein: Determining the plurality of residual values ​​includes determining the plurality of residual values ​​without applying an inverse transform to the plurality of residual values.

5. The method according to claim 1, wherein: Receiving the second flag includes receiving the second flag based on a quantization parameter (QP) being less than or equal to a threshold.

6. A method for encoding video data, the method comprising: determining that a block of a slice of the video data is to be decoded with transform skipping; determining a plurality of residual values ​​based on differences between the block of the video data to be decoded with transform skipping and a prediction block; determining to apply to the plurality of residual values ​​a type of decoding scheme between a first type of decoding scheme and a second type of decoding scheme, wherein according to the first type of decoding scheme, information indicating a position of a last significant value is signaled in a video bitstream for the block, and wherein according to the second type of decoding scheme, information indicating the position of the last significant value is not signaled in the video bitstream for the block; encoding the plurality of residual values ​​based on the determined type of decoding scheme, wherein, in encoding according to transform skipping, the plurality of residual values ​​are not transformed from the sample domain to the frequency domain and no transform is applied to the plurality of residual values; signaling a first flag in a video bitstream indicating whether transform skipping is enabled; signaling, based on whether transform skip is enabled, a second flag in a slice header of the slice into the video bitstream, the second flag indicating whether the first type of coding scheme or the second type of coding scheme is applied to the plurality of residual values; and Information indicating the position of the last valid value of the plurality of residual values ​​of the block is encoded into the video bitstream only if the first type of coding scheme is determined for the block decoded with transform skipping.

7. The method according to claim 6, wherein: The first type of coding scheme is a transform coefficient coding TRCC scheme, and the second type of coding scheme is a transform skip residual coding TSRC scheme, wherein the first type of coding scheme and the second type of coding scheme include: encoding a significance map of the block.

8. The method according to claim 6, wherein: Signaling the second flag includes signaling the second flag based on a quantization parameter (QP) being less than or equal to a threshold.

9. A device for decoding video data, the device comprising: a memory configured to store video data; as well as a processing circuit coupled to the memory and configured to: receiving a first flag from a video bitstream indicating whether transform skipping is enabled; receiving, based on the first flag indicating that transform skipping is enabled, a second flag in a slice header of a slice of the video data from the video bitstream, the second flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a plurality of residual values ​​of a block of the slice of the video data decoded with transform skipping, wherein, according to the first type of decoding scheme, information indicating a position of a last significant value is signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping, and wherein, according to the second type of decoding scheme, information indicating the position of the last significant value is not signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping; Based on the second flag, determining a type of decoding scheme between the first type of decoding scheme and the second type of decoding scheme; Based on the first flag, determining that a block of the slice is decoded with transform skipping; determining the plurality of residual values ​​of the block decoded with transform skipping based on the determined type of decoding scheme, wherein the processing circuit is further configured to: parse the information indicating the position of the last valid value of the plurality of residual values ​​from the video bitstream only if the first type of decoding scheme is determined, wherein the plurality of residual values ​​indicate differences between the block and a predicted block; and The block is reconstructed based on the determined plurality of residual values ​​and the prediction block, wherein the determined plurality of residual values ​​are not transformed from the sample domain to the frequency domain when the reconstruction is performed according to transform skipping.

10. The device according to claim 9, wherein: The first type of decoding scheme is a transform coefficient decoding TRCC scheme, and the second type of decoding scheme is a transform skip residual decoding TSRC scheme, wherein the first type of decoding scheme and the second type of decoding scheme include: decoding a significance map of the block.

11. The device according to claim 10, wherein: The number of flags indicating whether a residual value among the multiple residual values ​​is greater than a threshold in the TRCC scheme is a first value, wherein, in the TSRC scheme, the number of flags indicating whether the residual value among the multiple residual values ​​is greater than the threshold is a second value, and wherein the first value is different from the second value.

12. The device according to claim 9, wherein: To determine the plurality of residual values, the processing circuit is configured to determine the plurality of residual values ​​without applying an inverse transform to the plurality of residual values.

13. The apparatus according to claim 9, wherein: To receive the second flag, the processing circuit is configured to receive the second flag based on a quantization parameter (QP) being less than or equal to a threshold.

14. The apparatus according to claim 9, further comprising: A display configured to display a picture including the reconstructed block.

15. The apparatus according to claim 9, wherein: The device includes one or more of the following: a camera, a computer, a set-top box, or a wireless communication device.

16. The apparatus according to claim 9, wherein: The device includes one or more of the following: a mobile device, a broadcast receiver device.

17. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to: receiving a first flag from a video bitstream indicating whether transform skipping is enabled; Based on the first flag indicating that transform skipping is enabled, receiving a second flag in a slice header of a slice of video data from the video bitstream, the second flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a plurality of residual values ​​of blocks of the slice of the video data decoded with transform skipping, wherein according to the first type of decoding scheme, information indicating the position of the last significant value is signaled in the video bitstream for blocks of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping, and wherein, according to the second type of decoding scheme, information indicating the position of the last significant value is not signaled in the video bitstream for blocks of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping; Based on the second flag, determining a type of decoding scheme between the first type of decoding scheme and the second type of decoding scheme; Based on the first flag, determining that a block of the slice is decoded with transform skipping; determining the plurality of residual values ​​of the block decoded with transform skipping based on the determined type of decoding scheme, wherein the instructions further cause the processor to perform the following operations: parsing the information indicating the position of the last valid value of the plurality of residual values ​​from the video bitstream only if the first type of decoding scheme is determined, wherein the plurality of residual values ​​indicate differences between the block and a predicted block; and The block is reconstructed based on the determined plurality of residual values ​​and the prediction block, wherein the plurality of residual values ​​are not transformed from the sample domain to the frequency domain when reconstructing according to transform skipping.

18. A device for decoding video data, the device comprising: means for receiving from a video bitstream a first flag indicating whether transform skipping is enabled; means for receiving a second flag in a slice header of a slice of the video data, the second flag indicating whether a first type of decoding scheme or a second type of decoding scheme is applied to a plurality of residual values ​​of a block of the slice of the video data decoded with transform skipping, based on the first flag indicating enabling of transform skipping, wherein according to the first type of decoding scheme, information indicating a position of a last significant value is signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping, and wherein according to the second type of decoding scheme, information indicating the position of the last significant value is not signaled in the video bitstream for the block of the slice of the video data decoded with transform skipping, in which case no transform is applied to the plurality of residual values ​​of the block of the slice decoded with transform skipping; means for determining a type of decoding scheme between the first type of decoding scheme and the second type of decoding scheme based on the second flag; A unit for determining, based on the first flag, whether a block of the slice is decoded in a case of transform skipping; The unit for determining the plurality of residual values ​​of the block decoded with transform skipping based on the determined type of decoding scheme comprises: a unit for parsing the information indicating the position of the last valid value of the plurality of residual values ​​of the block from the video bitstream only if the first type of decoding scheme is determined, wherein the plurality of residual values ​​indicate differences between the block and a predicted block; and means for reconstructing the block based on the determined plurality of residual values ​​and the prediction block, wherein the determined plurality of residual values ​​are not transformed from the sample domain to the frequency domain when reconstructing according to transform skipping.

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