Advanced constraints for transform skip blocks in video coding

Abstract

An exemplary apparatus includes a memory and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to receive a first slice header syntax element for a slice of video data and determine a first value for the first slice header syntax element, the first value indicating whether dependency quantization is enabled. The one or more processors are configured to receive a second slice header syntax element for a slice of video data and determine a second value for the second slice header syntax element, the second value indicating whether symbol data hiding is enabled. The one or more processors are configured to determine whether transform skip residual coding is disabled for the slice based on the first value and the second value, and decode the slice based on the determination.

Description

[0001] This application claims priority to U.S. Patent Application No. 17 / 220,829, filed April 1, 2021, U.S. Provisional Patent Application No. 63 / 005,127, filed April 3, 2020, and U.S. Provisional Patent Application No. 63 / 012,134, filed April 18, 2020; the entire contents of each application are incorporated herein by reference. U.S. Patent Application No. 17 / 220,829, filed April 1, 2021, claims priority to U.S. Provisional Patent Application No. 63 / 005,127, filed April 3, 2020, and U.S. Provisional Patent Application No. 63 / 012,134, filed April 18, 2020. Technical Field

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

[0003] Digital video functionality may be incorporated into a 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, mobile devices (such as cellular or satellite radiotelephones or so-called "smartphones"), video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video coding techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-TH.263, ITU-TH.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-TH.265 / High Efficiency Video Coding (HEVC), and extensions of such standards. By implementing such video coding techniques, video devices may more efficiently transmit, receive, encode, decode, and / or store digital video information.

[0004] Video coding techniques include spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) can 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 prediction 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 prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to as reference frames. Summary of the Invention

[0005] In general, this disclosure describes techniques for applying high-level constraints to dependency quantization (DQ), sign data hiding (SDH), and syntax elements that indicate whether transform skip (TS) residual coding is enabled or disabled for a slice of video data. In some examples, this disclosure describes configuring a video encoder and a video decoder to disallow the use of DQ and SDH for blocks of video data that have TS residuals using transform residual coding (TRC). This disallowing the use of DQ and SDH for blocks that have TS residuals using TRC can prevent lossless coding operations from becoming lossy. The techniques of this disclosure can be implemented in a video coding standard such as Versatile Video Coding (VVC) or a future standard.

[0006] In one example, a method includes receiving a first slice header syntax element for a slice of video data; determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receiving a second slice header syntax element for the slice of the video data; determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determining whether transform skip residual coding is disabled for the slice based on the first value and the second value; and decoding the slice based on the determination.

[0007] In another example, a device includes: a memory; and one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to: receive a first slice header syntax element for a slice of the video data; determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decode the slice based on the determination.

[0008] In another example, an apparatus includes means for receiving a first slice header syntax element for a slice of the video data; means for determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; means for receiving a second slice header syntax element for the slice of the video data; means for determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; means for determining whether transform skip residual coding is disabled for the slice based on the first value and the second value; and means for decoding the slice based on the determination.

[0009] In another example, a non-transitory computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to: receive a first slice header syntax element for a slice of video data, determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice, receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice, determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value, and decode the slice based on the determination.

[0010] In another example, a method includes determining whether dependency quantization is enabled for a slice of video data; determining whether sign data hiding is enabled for the slice; determining whether transform skip residual decoding is disabled for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether sign data hiding is enabled for the slice; and encoding the slice based on the determination.

[0011] In another example, a device includes: a memory; and one or more processors implemented in circuitry and communicatively coupled to the memory, the one or more processors configured to: determine whether dependency quantization is enabled for a slice of video data; determine whether sign data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the determination as to whether dependency quantization is enabled for the slice or the determination as to whether sign data hiding is enabled for the slice; and encode the slice based on the determination.

[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 detailed description, accompanying drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0014] Figure 2A and 2B is a conceptual diagram illustrating an exemplary quadtree plus 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 exemplary video decoder that may perform the techniques of this disclosure.

[0017] Figure 5 is a flow chart illustrating a technique for preventing dependency quantization and sign data hiding for transform skip blocks coded using transform residuals, in accordance with the techniques of this disclosure.

[0018] Figure 6 is a flow chart illustrating other techniques for preventing dependency quantization and sign data hiding for transform skip blocks coded using transform residuals, in accordance with the techniques of this disclosure.

[0019] Figure 7 is a flow chart illustrating an exemplary technique for video encoding.

[0020] Figure 8 is a flow chart illustrating an exemplary technique for video decoding. DETAILED DESCRIPTION

[0021] In some draft video standards, certain lossy coding tools may be enabled for objects that could otherwise be losslessly coded. For example, in the draft video coding standard, there are two available residual coding processes: transform residual coding (TRC) and transform skip residual coding (TSRC). When TSRC is enabled, the TSRC process is typically used to decode transform skip (TS) blocks, but there are some decoding scenarios where TSRC may be disabled. When TSRC is disabled, the TRC process can be used to decode TS blocks. When TSRC is disabled (for example, TRC will be applied to TS blocks), lossy tools such as dependency quantization (DQ) and sign data hiding (SDH) may still be invoked for TS blocks. Typically, when a block is a TS block (as indicated by the TS flag), the block is intended to be losslessly coded. However, applying TRC to TS blocks can be problematic because DQ and SDH are implicitly lossy operations. Therefore, video encoders and decoders should generally not use DQ and SDH on blocks with TS residuals to ensure lossless decoding.

[0022] According to the techniques of this disclosure, a video encoder and a video decoder can be configured to disallow the use of DQ and SDH when a syntax element indicating whether TSRC decoding is disabled for a slice of video data is true, such as when slice_ts_residual_coding_disabled_flag, discussed in more detail below, is equal to 1. That is, according to the techniques of this disclosure, a video encoder and a video decoder can be configured so that TSRC is disabled only in decoding scenarios in which both DQ and SDH are also disabled, or in other words, the video encoder and the video decoder can be configured so that TSRC is enabled when at least one of DQ or SDH is also enabled. This can prevent decoding scenarios in which a TS block is decoded using TRC and becomes lossy when a lossless mode of operation is desired.

[0023] Video decoding (e.g., video encoding and / or video decoding) typically involves predicting a block of video data based on already decoded blocks of video data in the same picture (e.g., intra-frame prediction) or already decoded blocks of video data in a different picture (e.g., inter-frame prediction). In some cases, the video encoder also calculates residual data by comparing the predicted block to the original block. Thus, the residual data represents the difference between the predicted block and the original block. To reduce the number of bits required to signal the residual data, the video encoder can transform and quantize the residual data and signal the transformed and quantized residual data in the coded bitstream. The compression achieved by the transform and quantization process can be lossy, meaning that the transform and quantization process can introduce distortion into the decoded video data.

[0024] The video decoder decodes the residual data and adds it to the prediction block to produce a reconstructed video block that more closely matches the original video block than the prediction block alone. Due to losses introduced by the transformation and quantization of the residual data, the first reconstructed block may have distortion or artifacts. A common type of artifact or distortion is called blocking, in which the boundaries of the blocks used to decode the video data are visible.

[0025] To further improve the quality of the decoded video, the video decoder may perform one or more filtering operations on the reconstructed video blocks. Examples of these filtering operations include deblocking filtering, sample adaptive offset (SAO) filtering, and adaptive loop filtering (ALF). The parameters for these filtering operations may be determined by the video encoder and explicitly signaled in the coded video bitstream, or may be implicitly determined by the video decoder without explicitly signaling these parameters in the coded video bitstream.

[0026] In some decoding scenarios, a video encoder may encode video data in a transform skip mode, in which the transform process described above is not performed, i.e., the transform process is skipped. Therefore, for blocks encoded in transform skip mode, the residual data is not transformed. Residual blocks of video data encoded using transform skip mode may also be referred to as untransformed residual blocks. This disclosure describes techniques for implementing and signaling DQ, SDH, and TSRC.

[0027] According to the techniques of this disclosure, a video encoder and a video decoder can be configured to disallow the use of DQ and SDH when a syntax element indicating whether TSRC coding is disabled for a slice of video data is true. That is, according to the techniques of this disclosure, the video encoder and the video decoder can be configured so that TSRC is disabled only in coding scenarios where both DQ and SDH are also disabled. In other words, the video encoder and the video decoder can be configured so that TSRC is enabled when at least one of DQ or SDH is also enabled. This prevents coding scenarios in which a TS block is decoded using TRC and becomes lossy when a lossless mode of operation is desired. For example, a video decoder may receive a first slice header syntax element for a slice of video data, determine a first value for the first slice header syntax element, where the first value indicates whether dependent quantization is enabled for the slice, receive a second slice header syntax element for the slice of the video data, determine a second value for the second slice header syntax element, where the second value indicates whether symbol data hiding is enabled for the slice, determine whether transform skip residual coding is disabled for the slice based on the first and second values, and decode the slice based on the determination. In this way, the video decoder may prevent lossy coding tools from being applied to objects that would otherwise be lossless coded blocks.

[0028] Figure 1 is a block diagram illustrating an exemplary video encoding and decoding system 100 that can perform the techniques of this disclosure. The techniques of this disclosure generally 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, such as signaling data.

[0029] like Figure 1As shown in , in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a target device 116. Specifically, source device 102 provides the video data to target device 116 via computer-readable medium 110. Source device 102 and target device 116 may include any of a variety of devices, including desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, etc. In some cases, source device 102 and target device 116 may be equipped for wireless communication and, therefore, may be referred to as wireless communication devices.

[0030] exist Figure 1 In the example of , source device 102 includes video source 104, memory 106, video encoder 200 and output interface 108. Target 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 target device 116 can be configured to apply a technology for applying high-level constraints that can be applied to DQ, SDH and slice_ts_residual_coding_disabled_flag in video decoding. Therefore, source device 102 represents an example of a video encoding device, and target device 116 represents an example of a video decoding device. In other examples, source device and target device may include other components or arrangements. For example, source device 102 can receive video data from an external video source (such as an external camera). Similarly, target device 116 can be docked with an external display device, rather than including an integrated display device.

[0031] like Figure 1The system 100 shown in FIG is merely an example. In general, any digital video encoding and / or decoding device can implement the techniques for implementing the advanced constraints that can be imposed on DQ, SDH, and slice_ts_residual_coding_disabled_flag in video coding standards. Source device 102 and destination device 116 are merely examples of such decoding devices, where source device 102 generates decoded video data for transmission to destination device 116. This disclosure refers to a "decoding" device as a device that performs decoding (encoding and / or decoding) on ​​data. Thus, video encoder 200 and video decoder 300 represent examples of decoding devices, and more specifically, examples of video encoders and video decoders, respectively. In some examples, source device 102 and destination device 116 can operate in a substantially symmetrical manner, such that each of source device 102 and destination device 116 includes video encoding and decoding components. Thus, system 100 can support one-way or two-way video transmission between source device 102 and destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

[0032] Typically, video source 104 represents a source of video data (i.e., raw, unencoded video data) and provides a series of consecutive pictures (also referred to as "frames") of video data to video encoder 200, which encodes the picture data. Video source 104 of source device 102 may include a video capture device, such as a camera, a video archive containing previously captured raw video, and / or a video feed interface for receiving video from a video content provider. Alternatively, video source 104 may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from the order in which they were received (sometimes referred to as "display order") into a decoding order for decoding. Video encoder 200 may generate a bitstream comprising the encoded video data. Source device 102 may then output the encoded video data to computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of destination device 116.

[0033] Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memory. In some examples, memories 106 and 120 may store raw video data, such as raw video from video source 104 and raw decoded video data from video decoder 300. Additionally or alternatively, memories 106 and 120 may store software instructions executable by, for example, video encoder 200 and video decoder 300, respectively. Although memory 106 and memory 120 are shown as separate from video encoder 200 and video decoder 300 in this example, it should be understood that video encoder 200 and video decoder 300 may also include internal memory for functionally similar or equivalent purposes. Furthermore, memories 106 and 120 may store, for example, encoded video data output from video encoder 200 and input to video decoder 300. In some examples, portions of memories 106 and 120 may be allocated as one or more video buffers, for example, to store raw, decoded, and / or encoded video data.

[0034] The computer-readable medium 110 can represent any type of medium or device capable of transmitting encoded video data from the source device 102 to the target device 116. In one example, the computer-readable medium 110 represents a communication medium that enables the source device 102 to transmit the encoded video data directly to the target device 116 in real time (e.g., 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 can demodulate the transmitted signal including the encoded video data, and the input interface 122 can demodulate the received transmitted signal. The communication medium can include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium can form part of a packet-based network, such as a local area network, a wide area network, or a global network such as the Internet. The communication medium can include routers, switches, base stations, or any other device that can help facilitate communication from the source device 102 to the target device 116.

[0035] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0036] In some examples, source device 102 may output the encoded video data to a file server 114 or another intermediate storage device that can store the encoded video data generated by source device 102. Target device 116 may access the stored video data from file server 114 via streaming or downloading. File server 114 may be any type of server device capable of storing and transmitting the encoded video data to target device 116. File server 114 may represent a web server (e.g., for a website), a file transfer protocol (FTP) server, a content delivery network device, or a network attached storage (NAS) device. Target device 116 may access the encoded video data from file server 114 via 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. File server 114 and input interface 122 may be configured to operate according to a streaming protocol, a download transfer protocol, or a combination thereof.

[0037] The output interface 108 and the input interface 122 may represent wireless transmitters / receivers, modems, wired network connection 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 the output interface 108 and the input interface 122 include wireless components, the output interface 108 and the input interface 122 may be configured to transmit data, such as encoded video data, according to a cellular communication standard such as 4G, 4G-LTE (Long Term Evolution), LTE-Advanced, 5G, etc. In some examples where the output interface 108 includes a wireless transmitter, the output interface 108 and the input interface 122 may be configured to transmit data, such as encoded video data, according to other wireless standards such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBee TM ), Bluetooth TM Standards, 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 to perform the functions attributed to video encoder 200 and / or output interface 108, and destination device 116 may include a SoC device to perform the functions attributed to video decoder 300 and / or input interface 122.

[0038] The techniques of the present disclosure may be applied to support video decoding for 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.

[0039] The input interface 122 of the target 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 may include signaling information defined by the video encoder 200 (which is also used by the video decoder 300), such as syntax elements with values ​​describing characteristics and / or processing of video blocks or other decoded units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices, such as a 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.

[0040] although Figure 1 Although not shown, in some examples, video encoder 200 and video decoder 300 may each be integrated with an audio encoder and / or audio decoder and may include appropriate multiplexing-demultiplexing (MUX-DEMUX) units or other hardware and / or software to handle a multiplexed stream including both audio and video in a common data stream. If applicable, the MUX-DEMUX units may conform to the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

[0041] 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 execute the instructions in hardware using one or more processors to perform the technology of the present disclosure. Each of the video encoder 200 and the video decoder 300 can be included in one or more encoders or decoders, any of which can be integrated as part of a combined encoder / decoder (CODEC) in the corresponding device. A device including the video encoder 200 and / or the video decoder 300 may include an integrated circuit, a microprocessor, and / or a wireless communication device (such as a cellular phone).

[0042] 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 High Efficiency Video Coding (HEVC), or an extension thereof, such as the 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 latest draft of the VVC standard is in “Bross, et al. “Versatile Video Coding (Draft 8),” Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11,17 th Meeting: Brussels, BE, 7–17 Jan. 2020, JVET-Q2001-v15) (hereinafter referred to as “VVC Draft 8”). However, the technology of the present disclosure is not limited to any particular coding standard.

[0043] Typically, the video encoder 200 and video decoder 300 may perform block-based coding of a picture. The term "block" generally refers to a structure containing data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block may include a two-dimensional matrix of luma and / or chroma data samples. Typically, the video encoder 200 and video decoder 300 may decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, rather than decoding the red, green, and blue (RGB) data of the samples of a picture, the video encoder 200 and video decoder 300 may decode luma and chroma components, where the chroma components may include both red- and blue-hued chroma 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. Alternatively, pre-processing and post-processing units (not shown) may perform these conversions.

[0044] The present disclosure may generally relate to decoding (e.g., encoding and decoding) a picture, including the process of encoding or decoding the data of the picture. Similarly, the present disclosure may relate to decoding a block of a picture, including the process of encoding or decoding the data of the block, such as prediction and / or residual decoding. A coded video bitstream typically 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 block should generally be understood as decoding the values ​​of the syntax elements used to form the picture or block.

[0045] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video coder (such as the video encoder 200) partitions a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video coder partitions the CTU and CU into four identical 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 coder may further partition the PUs and TUs. For example, in HEVC, the residual quadtree (RQT) represents the partitioning of the TU. In HEVC, a PU represents inter-prediction data, and a TU represents residual data. An intra-predicted CU includes intra-prediction information, such as an intra-mode indication.

[0046] 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 (such as the video encoder 200) partitions a picture into multiple coding tree units (CTUs). The video encoder 200 may partition the CTU according to a tree structure, such as a quadtree plus binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure removes the concept of multiple partitioning types, such as the spacing between CUs, PUs, and TUs of HEVC. The QTBT structure includes two levels: a first level that is partitioned according to quadtree partitioning, and a second level that is 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).

[0047] 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. Ternary or ternary tree partitioning is a partitioning in which a block is split into three sub-blocks. In some examples, ternary or ternary tree partitioning divides a block into three sub-blocks without dividing the original block through the center. Partition types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0048] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma and chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for respective chroma components).

[0049] The video encoder 200 and the video decoder 300 can be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, or other partitioning structures according to HEVC. For explanation purposes, the description of the technology of the present disclosure is presented with respect to QTBT partitioning. However, it should be understood that the technology of the present disclosure can also be applied to video decoders configured to use quadtree partitioning or other types of partitioning.

[0050] In some examples, a CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples for a picture with three sample arrays, or a CTB of samples for a monochrome picture or a picture coded using three independent color planes and syntax structures for coding the samples. A CTB can be an NxN block of samples for some value of N, such that partitioning components into CTBs is partitioning. A component is an array or a single sample from one of the three arrays (luminance and two chroma) that make up a picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of such an array that makes up a picture in monochrome format. In some examples, a coding block is an MxN block of samples for some values ​​of M and N, such that partitioning a CTB into coding blocks is partitioning.

[0051] Blocks (e.g., CTUs or CUs) can be grouped in a picture in various ways. As an example, a brick can refer to a rectangular area of ​​a CTU row within a particular tile in a picture. A tile can be a rectangular area of ​​a CTU within a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular area of ​​a CTU having a height equal to the 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.

[0052] In some examples, a tile can be divided into multiple chunks, each of which can include one or more CTU rows within the tile. A tile that is not divided into multiple chunks can also be referred to as a chunk. However, a chunk that is a true subset of a tile cannot be referred to as a tile.

[0053] The tiles in a picture can also be arranged in the form of slices. A slice can be an integer number of tiles of a picture, which can be exclusively contained in a single network abstraction layer (NAL) unit. In some examples, a slice includes a continuous sequence of multiple complete tiles or just a complete tile of the tile.

[0054] This disclosure may use "NxN" 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, 16x16 samples or 16 by 16 samples. Typically, a 16x16 CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Likewise, 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 columns and rows. Furthermore, a CU does not necessarily have the same number of samples in the horizontal direction and in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0055] The video encoder 200 encodes video data representing prediction and / or residual information and other information for a CU. The prediction information indicates how the CU will be predicted to form a prediction block for the CU. The residual information typically represents the sample-by-sample difference between the samples of the CU and the prediction block before encoding.

[0056] To predict a CU, the video encoder 200 may typically form a prediction block for the CU via inter-prediction or intra-prediction. Inter-prediction generally refers to predicting a CU from data of a previously coded picture, while intra-prediction generally refers to predicting a CU from previously coded data of the same picture. To perform inter-prediction, the video encoder 200 may use one or more motion vectors to generate a prediction block. The video encoder 200 may typically perform a motion search to identify a reference block that closely matches the CU, for example, in terms of the difference between the CU and a reference block. The video encoder 200 may calculate a difference metric using sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), or other such difference calculations to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 may use unidirectional prediction or bidirectional prediction to predict the current CU.

[0057] Some examples of VVC also provide an affine motion compensation mode, which can be considered an inter-frame prediction mode. In the affine motion compensation mode, the video encoder 200 can determine two or more motion vectors representing non-translational motion (such as zooming in or out, rotation, perspective motion, or other irregular motion types).

[0058] To perform intra prediction, the video encoder 200 may select an intra prediction mode to generate a prediction block. Some examples of VVC provide sixty-seven intra prediction modes, including various directional modes as well as planar and DC modes. Typically, the video encoder 200 selects an intra prediction mode that describes predicting samples of the current block (e.g., a block of a CU) from samples adjacent to the current block. Assuming that the video encoder 200 codes CTUs and CUs in raster scan order (left to right, top to bottom), these samples may typically be above, above-left, or to the left of the current block in the same picture as the current block.

[0059] The video encoder 200 encodes data indicating a prediction mode for the current block. For example, for inter-frame prediction mode, the video encoder 200 may encode data indicating which of various available inter-frame prediction modes to use and motion information for the corresponding mode. For example, for unidirectional or bidirectional inter-frame prediction, 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.

[0060] After prediction of a block (such as intra-frame prediction or inter-frame prediction), the video encoder 200 may calculate residual data for the block. The residual data (such as a residual block) represents the sample-by-sample difference between the block and a prediction block for the block formed using the 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 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 primary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 generates transform coefficients after applying the one or more transforms.

[0061] Although examples in which a transform is performed are described above, in some examples, the transform may be skipped. For example, the video encoder 200 may implement a transform skip mode in which the transform operation is skipped. In examples in which the transform is skipped, the video encoder 200 may output coefficients corresponding to residual values ​​instead of transform coefficients. In the following description, the term "coefficient" should be interpreted as including coefficients corresponding to residual values ​​or transform coefficients generated from the results of a transform. Similarly, the term "coefficient block" should be interpreted as including a block of residual values ​​or a block of transform coefficients generated from the results of a transform.

[0062] As noted above, after transforming or transform skipping to generate coefficients, the video encoder 200 may perform quantization on the coefficients. Quantization generally refers to the process by which coefficients are quantized to potentially reduce the amount of data used to represent the coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 may reduce the bit depth associated with some or all of the coefficients. For example, the video encoder 200 may round 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 may perform a bitwise right shift of the value to be quantized.

[0063] After quantization, the video encoder 200 may scan the coefficients to produce a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients. For transform-coded blocks, the scan 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 coefficients using a predefined scan order to produce a serialized vector and then entropy encode the quantized coefficients of the vector. In other examples, the video encoder 200 may perform adaptive scanning. After scanning the quantized coefficients to form a one-dimensional vector, the video encoder 200 may entropy encode the one-dimensional vector, for example, according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy encode the values ​​of syntax elements that describe metadata associated with the encoded video data for use by the video decoder 300 in decoding the video data.

[0064] To perform CABAC, video encoder 200 may assign context within a context model to a symbol to be sent. The context may relate to, for example, whether neighboring values ​​of the symbol are zero values. The probability determination may be based on the context assigned to the symbol.

[0065] Video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, to video decoder 300, for example, in a picture header, block header, slice header, or other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). Video decoder 300 may likewise decode such syntax data to determine a manner to decode the corresponding video data.

[0066] In this way, the video encoder 200 can generate a bitstream including encoded video data (e.g., syntax elements describing the partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual information for the blocks). Finally, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0067] In general, the video decoder 300 performs a process that is inverse to 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 syntax elements of the bitstream in a manner substantially similar to, but inverse to, the CABAC encoding process of the video encoder 200. The syntax elements may define partitioning information for partitioning a picture into CTUs and partitioning each CTU according to a corresponding partitioning structure (such as a QTBT structure) to define CUs of the CTU. The syntax elements may further define prediction and residual information for a block of video data (e.g., a CU).

[0068] The residual information may be represented by, for example, quantized coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized coefficients of the block to reproduce a residual block for the block. For blocks coded in transform skip mode, the video decoder 300 skips the inverse transform process. The video decoder 300 uses the signaled prediction mode (intra-frame 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 with the residual block (sample by sample) to reproduce the original block. The video decoder 300 may perform additional processing, such as a deblocking process to reduce visual artifacts along block boundaries.

[0069] According to the techniques of this disclosure, a method includes receiving a first slice header syntax element for a slice of video data; determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receiving a second slice header syntax element for the slice of the video data; determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determining whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decoding the slice based on the determination.

[0070] According to the technology of the present disclosure, a device includes: a memory configured to store the video data; and one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: receive a first slice header syntax element for a slice of the video data; determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decode the slice based on the determination.

[0071] According to the techniques of this disclosure, a device includes: means for receiving a first slice header syntax element for a slice of video data; means for determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; means for receiving a second slice header syntax element for the slice of the video data; means for determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; means for determining whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and means for decoding the slice based on the determination.

[0072] According to the technology of the present disclosure, a non-transitory computer-readable storage medium has instructions stored thereon, which, when executed, cause one or more processors to: receive a first slice header syntax element for a slice of video data, determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice, receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice, determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value, and decode the slice based on the determination.

[0073] According to the technology of the present disclosure, a method includes: determining whether dependency quantization is enabled for a slice of video data; determining whether symbol data hiding is enabled for the slice; determining whether transform skip residual decoding is disabled for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether symbol data hiding is enabled for the slice; and encoding the slice based on the determination.

[0074] According to the technology of the present disclosure, a device includes: a memory; and one or more processors, which are implemented in circuits and communicatively coupled to the memory, and the one or more processors are configured to: determine whether dependency quantization is enabled for a slice of video data; determine whether sign data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the determination as to whether dependency quantization is enabled for the slice or the determination as to whether sign data hiding is enabled for the slice; and encode the slice based on the determination.

[0075] This disclosure may generally refer to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to conveying the values ​​of syntax elements and / or other data used to decode encoded video data. That is, video encoder 200 may signal the values ​​of syntax elements in a bitstream. Generally, signaling refers to generating values ​​in a bitstream. As mentioned above, source device 102 may transmit the bitstream to destination device 116 in substantially real time, or in a non-real-time manner, such as may occur when syntax elements are stored on storage device 112 for later retrieval by destination device 116.

[0076] Figure 2A and 2B is a conceptual diagram illustrating an exemplary quadtree plus 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, there is no need to indicate the split type because the quadtree node splits a block horizontally and vertically into 4 sub-blocks of equal size. Therefore, the video encoder 200 can encode syntax elements (such as split information) at the region tree level (i.e., solid lines) of the QTBT structure 130 and syntax elements (such as split information) at the prediction tree level (i.e., dashed lines) of the QTBT structure 130, and the video decoder 300 can decode these syntax elements. The video encoder 200 may encode video data (such as prediction data and transform data) of the CU represented by the terminal leaf node of the QTBT structure 130 , and the video decoder 300 may decode the video data.

[0077] 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, indicating the minimum allowed quadtree leaf node size), a maximum binary tree size (MaxBTSize, indicating the maximum allowed binary tree root node size), a maximum binary tree depth (MaxBTDepth, indicating the maximum allowed binary tree depth), and a minimum binary tree size (MinBTSize, indicating the minimum allowed binary tree leaf node size).

[0078] The root node of the QTBT structure corresponding to the CTU can have four child nodes at the first level of the QTBT structure, each of which can be split according to the quadtree partitioning. That is, the nodes at the first level are leaf nodes (no child nodes) or have four child nodes. The example of the QTBT structure 130 represents such nodes as including parent nodes and child nodes with branches represented by solid lines. If the node at the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), the node can be further split by the corresponding binary tree. The binary tree splitting of a node can be iterated until the node resulting 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 nodes as branches represented by dotted lines. The binary tree leaf nodes are called decoding units (CUs), which are used for prediction (e.g., intra-frame picture or inter-frame picture prediction) and transformation without any further partitioning. As discussed above, CUs can also be referred to as "video blocks" or "blocks."

[0079] In one example of a QTBT partitioning structure, the CTU size is set to 128x128 (luminance sample and two corresponding 64x64 chroma samples), MinQTSize is set to 16x16, MaxBTSize is set to 64x64, MinBTSize (for width and height) is set to 4, and MaxBTDepth is set to 4. Quadtree partitioning is first applied to the CTU to generate quadtree leaf nodes. The size of the quadtree leaf node can range from 16x16 (i.e., MinQTSize) to 128x128 (i.e., the CTU size). If the leaf quadtree node is 128x128, the leaf quadtree node will not be further split by the binary tree because the size exceeds MaxBTSize (i.e., 64x64, in this example). Otherwise, the quadtree leaf node will be further split by the binary tree. Therefore, the quadtree leaf node is also the root node of the binary tree and its binary tree depth is 0. When the binary tree depth reaches MaxBTDepth (4 in this example), further splitting is not allowed. A binary tree node with a width equal to MinBTSize (4 in this example) implies that no further vertical splits are allowed. Similarly, a binary tree node with a height equal to MinBTSize implies that no further horizontal splits are allowed for the binary tree node. As mentioned above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further partitioning.

[0080] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3This is provided for illustrative purposes and should not be considered limiting of the techniques broadly exemplified and described in this disclosure. For illustrative purposes, this disclosure describes the video encoder 200 based on the techniques of VVC (ITU-T H.266 in development) and HEVC (ITU-T H.265). However, the techniques of this disclosure may be performed by video encoding devices configured for other video coding standards.

[0081] exist Figure 3 In the example of FIG, 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 or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or processing circuits. For example, the units of the video encoder 200 may be implemented as one or more circuits or logic elements as part of a hardware circuit or as part of a processor, ASIC, or FPGA. Furthermore, the video encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.

[0082] 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 video data stored in the video data memory 230. The DPB 218 can act as a reference picture memory that stores reference video data for use in predicting subsequent video data by the video encoder 200. The video data memory 230 and the 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. The video data memory 230 and the DPB 218 can be provided by the same memory device or separate memory devices. In various examples, the 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.

[0083] In this 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 of 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 .

[0084] Figure 3 The various units are shown to assist in understanding the operations performed by the video encoder 200. The units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. A fixed-function circuit refers to a circuit that provides a specific function and pre-sets the operations that can be performed. A programmable circuit refers to a circuit that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. A fixed-function circuit may execute software instructions (e.g., to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally immutable. In some examples, one or more of 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.

[0085] 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 programmable circuits. In an example where the operation of the video encoder 200 is performed using software executed by programmable circuits, the memory 106 ( Figure 1 ) may store instructions (eg, object code) for software received and executed by the video encoder 200, or another memory (not shown) within the video encoder 200 may store such instructions.

[0086] The video data memory 230 is configured to store received video data. The video encoder 200 may retrieve a picture of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 may be original video data to be encoded.

[0087] 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 for performing video prediction according to other prediction modes. For 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.

[0088] 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 the partitioning of CTUs into CUs, the prediction mode for a CU, the transform type for the residual data of a CU, the quantization parameter for the 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 the other tested combinations.

[0089] The video encoder 200 may partition a picture retrieved from the video data memory 230 into a series of CTUs and pack one or more CTUs into a slice. The mode select unit 202 may partition the CTUs of the picture according to a tree structure, such as the QTBT structure described above or the quadtree structure of HEVC. 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."

[0090] Typically, mode select unit 202 also controls its components (e.g., motion estimation unit 222, motion compensation unit 224, and intra prediction unit 226) to generate a prediction block for the current block (e.g., the current CU, or, in HEVC, the overlapping portion of a PU and TU). For inter prediction of the current block, 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 coded pictures stored in DPB 218). Specifically, motion estimation unit 222 may calculate values ​​representing how similar potential reference blocks are to the current block, such as based on sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), and the like. Motion estimation unit 222 may typically perform these calculations using the sample-by-sample differences between the current block and the reference block under consideration. Motion estimation unit 222 may identify the reference block with the smallest value resulting from these calculations, thereby indicating the reference block that most closely matches the current block.

[0091] Motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of the current block in the current picture. Motion estimation unit 222 may then provide the motion vectors to motion compensation unit 224. For example, for unidirectional inter prediction, motion estimation unit 222 may provide a single motion vector, while for bidirectional inter prediction, motion estimation unit 222 may provide two motion vectors. Motion compensation unit 224 may then use the motion vectors to generate a prediction block. For example, 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, motion compensation unit 224 may interpolate the values ​​of the prediction block according to one or more interpolation filters. Furthermore, for bidirectional inter prediction, motion compensation unit 224 may retrieve data for the two reference blocks identified by the corresponding motion vectors and combine the retrieved data, for example, via sample-by-sample averaging or weighted averaging.

[0092] As another example, for intra prediction or intra prediction coding, the intra prediction unit 226 may generate a prediction block from samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 may mathematically approximate the values ​​of neighboring samples and fill these calculated values ​​in a defined direction across the current block to generate a prediction block. As another example, for DC mode, the intra prediction unit 226 may calculate the average of samples adjacent to the current block and generate a prediction block to include this obtained average value for each sample of the prediction block.

[0093] Mode selection unit 202 provides the prediction block to residual generation unit 204. Residual generation unit 204 receives the original, unencoded version of the current block from video data memory 230 and the prediction block from mode selection unit 202. 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, residual generation unit 204 may also determine the difference between sample values ​​in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0094] In the example where the mode select 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 indicated above, the size of a CU may refer to the size of the luma coding block of the CU, while the size of a PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2Nx2N, the video encoder 200 may support PU sizes of 2Nx2N or NxN for intra prediction, and symmetric PU sizes of 2Nx2N, 2NxN, Nx2N, NxN, or similar for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning of PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

[0095] In examples where mode select unit 202 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 indicated above, the size of a CU may refer to the size of the luma coding block of the CU. Video encoder 200 and video decoder 300 may support CU sizes of 2N×2N, 2N×N, or N×2N.

[0096] 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), mode selection unit 202 generates a prediction block for the current block being encoded via the corresponding unit associated with the coding technique. In some examples, such as palette mode coding, mode selection unit 202 may not generate a prediction block, but instead generates syntax elements that indicate how to reconstruct the block based on the selected palette. In such modes, mode selection unit 202 may provide these syntax elements to entropy coding unit 220 to be encoded.

[0097] As described above, the residual generation unit 204 receives video data for a current block and a corresponding prediction block. The residual generation unit 204 then generates a residual block for the current block. To generate the residual block, the residual generation unit 204 calculates the sample-by-sample difference between the prediction block and the current block.

[0098] The transform processing unit 206 applies one or more transforms to the residual block to produce a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 may apply various transforms to the residual block to form the transform coefficient block. For example, the transform processing unit 206 may 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 may perform multiple transforms on the residual block, such as a primary transform and a secondary transform, such as a rotation transform. In some examples, the transform processing unit 206 does not apply a transform to the residual block. For blocks coded in transform skip mode, the transform processing unit 206 may be treated as a pass-through unit that does not change the received values.

[0099] In some examples, transform processing unit 206 and / or mode selection unit 202 may determine a first value for a first slice header syntax element of a slice of video data, the first value indicating whether dependency quantization is enabled for the slice. Transform processing unit 206 and / or mode selection unit 202 may determine a second value for a second slice header syntax element of the slice, the second value indicating whether symbol data hiding is enabled for the slice. Transform processing unit 206 and / or mode selection unit 202 may also determine whether transform skip residual coding is disabled for the slice.

[0100] Quantization unit 208 may quantize the coefficients in a coefficient block to produce a quantized coefficient block. Quantization unit 208 may quantize the coefficients of the coefficient block according to a quantization parameter (QP) value associated with the current block. Video encoder 200 (e.g., via mode select unit 202) may adjust the degree of quantization applied to the coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce a loss of information, and therefore, the quantized coefficients may have lower precision than the original coefficients generated by transform processing unit 206.

[0101] 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 a residual block based on the transform coefficient block. The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (albeit 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 of the prediction block generated by the mode selection unit 202 to generate the reconstructed block. For blocks coded in transform skip mode, the inverse transform processing unit 212 may be considered as a pass-through unit that does not change the received values.

[0102] Filter unit 216 may perform one or more filtering operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edges of the CU. In some examples, the operations of filter unit 216 may be skipped.

[0103] The video encoder 200 stores the reconstructed block 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 block 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 block 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 possibly filtered) block 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 block of the current picture in the DPB 218 to perform intra-frame prediction on other blocks in the current picture.

[0104] In general, entropy coding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy coding unit 220 may entropy encode quantized coefficient blocks from quantization unit 208. As another example, entropy coding unit 220 may entropy encode prediction syntax elements (e.g., motion information for inter-frame prediction or intra-frame mode information for intra-frame prediction) from mode selection unit 202. Entropy coding unit 220 may perform one or more entropy encoding operations on the syntax elements (which is another example of video data) to generate entropy-encoded data. For example, 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 partitioned entropy (PIPE) coding operation, an indexed Golomb coding operation, or another type of entropy coding operation on the data. In some examples, entropy coding unit 220 may operate in a bypass mode, in which the syntax elements are not entropy encoded.

[0105] The video encoder 200 may output a bitstream including entropy-encoded syntax elements required to reconstruct a block of a slice or picture. Specifically, the entropy encoding unit 220 may output a bitstream.

[0106] The operations described above are described for blocks. This description 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 and chroma components of a CU. In some examples, the luma coding blocks and chroma coding blocks are the luma and chroma components of a PU.

[0107] In some examples, the operations performed for luma coding blocks do not need to be repeated for chroma coding blocks. As an example, the operations for identifying the motion vector (MV) and reference picture for the luma coding block do not need to be repeated to identify the MV and reference picture for the chroma blocks. Rather, the MV of the luma coding block can be scaled to determine the MV for the chroma blocks, and the reference picture can be the same. As another example, the intra prediction process can be the same for luma coding blocks and chroma coding blocks.

[0108] Video encoder 200 represents an example of a device configured to encode video data, the device comprising: a memory configured to store the video data; one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: determine whether dependency quantization is enabled for a slice of the video data; determine whether sign data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the determination as to whether dependency quantization is enabled for the slice or the determination as to whether sign data hiding is enabled for the slice; and encode the slice based on the determination.

[0109] Figure 4 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Figure 4 This is provided for illustrative purposes and is not intended to limit the techniques broadly illustrated and described in this disclosure. For illustrative purposes, this disclosure describes video decoder 300 based on the techniques of VVC (ITU-T H.266 in development) and HEVC (ITU-T H.265). However, the techniques of this disclosure may be performed by video coding devices configured for other video coding standards.

[0110] exist Figure 4 In the example of FIG, 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 CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 314 may be implemented in one or more processors or processing circuits. For example, the units of video decoder 300 may be implemented as one or more circuits or logic elements as part of a hardware circuit or as part of a processor, FPGA, or ASIC. Furthermore, video decoder 300 may include additional or alternative processors or processing circuits to perform these and other functions.

[0111] 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 prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra-block copy unit (which may form part of the motion compensation unit 316), an affine unit, a linear model (LM) unit, etc. In other examples, the video decoder 300 may include more, fewer, or different functional components.

[0112] CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of video decoder 300. The video data may be, for example, stored from computer readable medium 110 ( Figure 1 ) obtains video data stored in CPB memory 320. CPB memory 320 may include a CPB that stores coded video data (e.g., syntax elements) from a coded video bitstream. Furthermore, memory 320 may store video data other than syntax elements for decoded pictures, such as temporary data representing outputs from various units of video decoder 300. DPB 314 typically stores decoded pictures, which video decoder 300 may output and / or use as reference video data when decoding subsequent data or pictures in the coded video bitstream. CPB memory 320 and DPB 314 may be formed from 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 by separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300 or off-chip relative to those components.

[0113] 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 store data as discussed above through CPB memory 320. Similarly, when some or all functions of video decoder 300 are 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.

[0114] Figure 4 The various units shown in FIG are shown to aid in understanding the operations performed by the video decoder 300. The 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 have pre-set executable operations. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functions in the executable operations. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. Fixed-function circuits can execute software instructions (for example, to receive parameters or output parameters), but the type of operation performed by the fixed-function circuit is generally 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.

[0115] The video decoder 300 may include an ALU, an EFU, digital circuits, analog circuits, and / or a programmable core formed by programmable circuits. In examples where the operation of the video decoder 300 is performed by software executed on the programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software that the video decoder 300 receives and executes.

[0116] The entropy decoding unit 302 may receive the encoded video data from the PCB memory and perform entropy decoding on the video data to reproduce 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.

[0117] Typically, the video decoder 300 reconstructs a picture block by block. The video decoder 300 may perform a reconstruction operation on each block separately (where the currently reconstructed (ie, decoded) block may be referred to as a "current block").

[0118] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized coefficients of the quantized 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 coefficient block to determine a degree of quantization and also 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 coefficients. The inverse quantization unit 306 may thereby form a coefficient block comprising the coefficients.

[0119] After inverse quantization unit 306 forms a coefficient block, inverse transform processing unit 308 may apply one or more inverse transforms to the coefficient block to produce a residual block associated with the current block. For example, inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karnau-Loev transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the coefficient block. For blocks coded in transform skip mode, inverse transform processing unit 308 may be treated as a pass-through unit that does not change the received values.

[0120] In some examples, the inverse transform processing unit 308 and / or the entropy decoding unit 302 may determine a first value for a first slice header syntax element of a slice of video data, the first value indicating whether dependency quantization is enabled for the slice. The inverse transform processing unit 308 and / or the entropy decoding unit 302 may determine a second value for a second slice header syntax element of the slice, the second value indicating whether symbol data hiding is enabled for the slice. The inverse transform processing unit 308 and / or the entropy decoding unit 302 may determine whether transform skip residual coding is disabled for the slice.

[0121] 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 may generate the prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which the reference block is retrieved and a motion vector that identifies the position of the reference block in the reference picture relative to the position of the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in a manner substantially similar to that described with respect to motion compensation unit 224 ( Figure 3 ) performs the inter-frame prediction process in the manner described.

[0122] 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. Furthermore, the intra-prediction unit 318 may generally generate a prediction block in a manner substantially similar to that described with respect to the intra-prediction unit 226 ( Figure 3 The intra prediction process is performed in the manner described in ). The intra prediction unit 318 can retrieve data of samples adjacent to the current block from the DPB 314.

[0123] The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.

[0124] The filter unit 312 may perform one or more filtering 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.

[0125] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in examples where the operations of the filter unit 312 are not performed, the reconstruction unit 310 may store the reconstructed block to the DPB 314. In examples where the operations of the filter unit 312 are 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 previously decoded pictures for subsequent motion compensation and samples of the current picture for intra prediction) 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 subsequent presentation on a display such as a video processor. Figure 1 on the display device 118 of the display device.

[0126] Thus, the video decoder 300 represents an example of a device for decoding video data, the device comprising: a memory configured to store video data; and one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: receive a first slice header syntax element for a slice of the video data; determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receive a second slice header syntax element for a slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decode the slice based on the determination.

[0127] This disclosure describes techniques for preventing originally lossless decoding from becoming lossy. According to the techniques of this disclosure, advanced constraints can be employed for decoding transform skip blocks that use transform residual coding schemes (e.g., residual_coding() in VVC draft 8). Specifically, when transform skip blocks use transform residual coding, advanced constraints prevent the use of dependency quantization and sign data hiding.

[0128] In VVC draft 8, there are two available residual coding schemes. The first is TRC (e.g., residual_coding()), and the second is TSRC (e.g., residual_coding_ts()). In this example, residual_coding() and residual_coding_ts() represent two different syntax structures for parsing or processing residual samples. Therefore, TRC and TSRC are two different schemes for decoding the transform residual of a block of video data. TSRC should not be confused with TS mode, as TSRC is a coding scheme that can be applied to the residual of a TS mode block.

[0129] TS is a mode in VVC that is explicitly signaled using the TS mode flag as part of the Multiple Transform Selection (MTS) signaling, or is implicitly selected if the Block Differential Pulse Coded Modulation (BDPCM) mode is selected. If the TS flag is 1, TSRC is used for coefficient coding as normal, unless slice_ts_residual_coding_disabled_flag is equal to 1, in which case TRC is used to encode the coefficients of the TS block. The signaling of slice_ts_residual_coding_disabled_flag is currently performed in the slice header. It should be noted that if the TS flag is 0 (e.g., the block is not a TS block) and slice_ts_residual_coding_disabled_flag is equal to 0, TRC can be applied to the block, although TSRC is enabled for the slice containing the block.

[0130] In VVC draft 8, DQ and SDH were initially introduced as tools to work with TRC. However, when slice_ts_residual_coding_disabled_flag is set to 1, DQ and SDH can also be invoked for TS blocks. This can be problematic for lossless decoding, as lossless decoding is based on TS flags, and DQ and SDH are implicitly lossy operations. Therefore, the video encoder 200 and the video decoder 300 should not use DQ and SDH for blocks with TS residuals to ensure lossless decoding.

[0131] According to the techniques of this disclosure, when a syntax element indicates that TSRC is disabled, for example, slice_ts_residual_coding_disabled_flag is equal to 1, the use of DQ and SDH can be disabled at a higher level. This can prevent TS blocks using TRC from becoming lossy when a lossless mode of operation is desired. An example is provided below.

[0132] Example 1:

[0133] In Example 1, ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag are moved from the picture header to the slice level after the signaling of slice_ts_residual_coding_disabled_flag. The signaling of the new slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag is then constrained based on slice_ts_residual_coding_disabled_flag. In this case, when slice_ts_residual_coding_disabled_flag = 1, slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag are not signaled (inferred to be 0). For example, when slice_ts_residual_coding_disabled_flag=1, the video encoder 200 may not signal slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag, and when slice_ts_residual_coding_disabled_flag=1, the video decoder 300 may infer that slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag are 0.

[0134] The following provides example normative text changes to VVC Draft 8. The start of a removal of a syntax element is shown with <DELETE> and the end of the removal is marked with < / DELETE>, and the start of an addition / modification is shown with <CHANGE> and the end of the addition / modification is marked with < / CHANGE>.

[0135] 7.3.2.7 Picture header structure syntax

[0136]

[0137]

[0138] 7.3.7.1 Generic Slice Header Syntax

[0139]

[0140] 7.4.3.7 Image header structure semantics

[0141] <DELETE> ph_dep_quant_enabled_flag equal to 0 specifies that dependency quantization is disabled for the current picture. ph_dep_quant_enabled_flag equal to 1 specifies that dependency quantization is enabled for the current picture. When ph_dep_quant_enabled_flag is not present, it is inferred to be equal to 0.

[0142] pic_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for the current picture. pic_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding is enabled for the current picture. When pic_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0.

[0143]

[0144] 7.4.8.1 Generic Slice Header Semantics

[0145] slice_ts_residual_coding_disabled_flag equal to 1 specifies that the residual_coding() syntax structure is used to parse residual samples for transform skip blocks of the current slice. slice_ts_residual_coding_disabled_flag equal to 0 specifies that the residual_ts_coding() syntax structure is used to parse residual samples for transform skip blocks of the current slice. When slice_ts_residual_coding_disabled_flag is not present, it is inferred to be equal to 0.

[0146] <CHANGE> slice_dep_quant_enabled_flag equal to 0 specifies that dependent quantization is disabled for the current picture. slice_dep_quant_enabled_flag equal to 1 specifies that dependent quantization is enabled for the current picture. When slice_dep_quant_enabled_flag is not present, it is inferred to be equal to 0.

[0147] slice_sign_data_hiding_enabled_flag equal to 0 specifies that sign bit hiding is disabled for the current picture. slice_sign_data_hiding_enabled_flag equal to 1 specifies that sign bit hiding is enabled for the current picture. When slice_sign_data_hiding_enabled_flag is not present, it is inferred to be equal to 0.

[0148] Example 2:

[0149] In Example 2, as in Example 1, ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag are moved from the picture header to the slice level. However, in Example 2, ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag are placed before the signaling of slice_ts_residual_coding_disabled_flag. Slice_ts_residual_coding_disabled_flag is constrained based on slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag. In this case, when either slice_dep_quant_enabled_flag or slice_sign_data_hiding_enabled_flag is 1, slice_ts_residual_coding_disabled_flag is not signaled but inferred to be 0. For example, when slice_dep_quant_enabled_flag or slice_sign_data_hiding_enabled_flag or both are 1, the video encoder 200 may not signal slice_ts_residual_coding_disabled_flag, and when slice_dep_quant_enabled_flag or slice_sign_data_hiding_enabled_flag or both are 1, the video decoder 300 may infer slice_ts_residual_coding_disabled_flag to be 0.

[0150] For example, the video decoder 300 may receive a first slice header syntax element (e.g., slice_dep_quant_enabled_flag) for a slice of video data, determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice, receive a second slice header syntax element (e.g., slice_sign_data_hiding_enabled_flag) for a slice of video data, determine a second value for the second slice header syntax element, wherein the second value indicates whether sign data hiding is enabled for the slice, determine whether transform skip residual coding is disabled for the slice based on the first value and the second value, and decode the slice based on the determinations. For example, as part of determining whether transform skip residual coding is disabled for the slice, the video decoder 300 may determine that transform skip residual coding is enabled for the slice in response to one or both of the first value indicating that dependency quantization is enabled for the slice and the second value indicating that sign data hiding is enabled for the slice. In such an example, video decoder 300 may infer that a third slice header syntax element (eg, slice_ts_residual_coding_disabled_flag), indicating whether transform skip residual coding is disabled for the slice, is set to a value indicating that transform skip residual coding is enabled for the slice.

[0151] In some examples, as part of determining whether transform skip residual coding is disabled for the slice, the video decoder 300 may, in response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that sign data hiding is disabled for the slice, receive a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice. In some examples, the third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein as part of decoding the slice, in response to determining that a block of the slice is encoded in transform skip mode, the video decoder 300 decodes the block using transform residual coding while avoiding use of dependency quantization and sign data hiding for the block.

[0152] The following provides example normative text changes to VVC Draft 8. The start of a removal of a syntax element is shown with <DELETE> and the end of the removal is marked with < / DELETE>, and the start of an addition / modification is shown with <CHANGE> and the end of the addition / modification is marked with < / CHANGE>.

[0153] 7.3.2.7 Picture header structure syntax

[0154]

[0155] 7.3.7.1 Generic Slice Header Syntax

[0156]

[0157]

[0158] Example 3:

[0159] In Example 3, ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag are retained in the picture header. However, the signaling of slice_ts_residual_coding_disabled_flag is conditional based on the two aforementioned flags, ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag. For example, the video encoder 200 may not signal slice_ts_residual_coding_disabled_flag based on the values ​​of ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag. The video decoder 300 may infer the value of slice_ts_residual_coding_disabled_flag based on the values ​​of ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag.

[0160] The following provides exemplary specification text changes to VVC Draft 8. The start of an addition / modification is shown with <CHANGE>, and the end of an addition / modification is marked with < / CHANGE>.

[0161] 7.3.7.1 Generic Slice Header Syntax

[0162]

[0163]

[0164] Example 4:

[0165] In Example 4, the use of DQ and SDH is implicitly disabled in residual_coding() based on the slice level flag slice_ts_residual_coding_disabled_flag. For example, the video encoder 200 and the video decoder 300 may not use DQ or SDH based on slice_ts_residual_coding_disabled_flag. The start of the addition / modification of VVC Draft 8 is shown with <CHANGE>, and the end of the addition / modification is marked with < / CHANGE>.

[0166] 7.3.10.11 Residual decoding syntax

[0167]

[0168]

[0169]

[0170]

[0171]

[0172] In all four examples, dependency quantization and sign data hiding methods are prohibited for transform skip blocks that use TRC to code the residual.

[0173] Example 5:

[0174] Based on Example 2 above, optional signaling of ph_dep_quant_info_in_ph_flag and ph_sign_data_hiding_info_in_ph_flag in the PPS, indicating the presence of DQ and SDH information, can be added to the picture header (PH) syntax structure. If the video encoder 200 signals DQ or SDH in the PH, the video encoder 200 may not signal the slice-level slice_dep_quant_enabled_flag and / or slice_sign_data_hiding_enabled_flag, and the video decoder 300 may infer their values ​​to be equal to the values ​​signaled in the picture header. If this flag information is not signaled in the PH, it can be signaled in the slice header as in Example 2. In addition to Example 2, the presence of slice_residual_coding_disabled_flag can also be conditional on TS enablement at the SPS level (e.g., support for TS) and support for slice-level switching between TSRC and TRC for TS blocks signaled by slice_residual_coding_disabled_flag. Support for signaling slice-level switching between TSRC and TRC can be controlled by a flag in the PPS or an SPS-level flag. The PPS-level flag pps_ts_residual_coding_override_flag or the SPS-level sps_ts_residual_coding_override_flag can be used to gate the presence of slice_residual_coding_disabled_flag, as shown in the specification text below.

[0175] In the case where the video encoder 200 does not signal ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag in the PH, making the slice-level slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag conditional on the PH-level ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag and signaling their presence in the PPS can be omitted. With this technique, hierarchical signaling of DQ and SDH flags at the picture level and slice level can be achieved.

[0176] Additions and modifications related to VVC draft script 8 are shown below (where changes are shown within the <CHANGE> and < / CHANGE> tags).

[0177] 7.3.2.3 Sequence Parameter Set RBSP Syntax

[0178]

[0179] 7.3.2.4 Picture Parameter Set RBSP Syntax

[0180]

[0181] 7.3.2.4 Picture Parameter Set RBSP Syntax

[0182]

[0183]

[0184] 7.3.2.7 Picture header structure syntax

[0185]

[0186] In some examples, the subclause may be moved to a position after the subclause in the RBSP trailing bits syntax.

[0187] 7.3.7.1 Generic Slice Header Syntax

[0188]

[0189] or

[0190]

[0191] <change>

[0192] sps_residual_coding_override_present_flag equal to 1 specifies that ts_residual_coding_disabled_flag is present in the slice header referencing the SPS. ts_residual_coding_override_present_flag equal to 0 specifies that ts_residual_coding_disabled_flag is not present in the slice header referencing the SPS. When not present, the default value of sps_residual_coding_override_present_flag is equal to 0.

[0193] < / change>

[0194] In other examples, the changes may be as follows:

[0195] <change>

[0196] pps_residual_coding_override_present_flag equal to 1 specifies that ts_residual_coding_disabled_flag is present in the slice header referencing the PPS. ts_residual_coding_override_present_flag equal to 0 specifies that ts_residual_coding_disabled_flag is not present in the slice header referencing the PPS. When not present, the default value of pps_residual_coding_override_present_flag is equal to 0.

[0197] dep_quant_info_in_ph_flag equal to 1 specifies that dependency quantization information is present in the PH syntax structure and is not present in slice headers that reference a PPS and do not contain a PH syntax structure. dep_quant_info_in_ph_flag equal to 0 specifies that dependency quantization information is not present in the PH syntax structure and may be present in slice headers that reference a PPS and do not contain a PH syntax structure.

[0198] sign_data_hiding_info_in_ph_flag equal to 1 specifies that the sign data hiding information is present in the PH syntax structure and is not present in slice headers that reference a PPS and do not contain a PH syntax structure. sign_data_hinding_info_in_ph_flag equal to 0 specifies that the sign data hiding information is not present in the PH syntax structure and may be present in slice headers that reference a PPS and do not contain a PH syntax structure.

[0199] < / change>

[0200] In other examples, the changes may be as follows:

[0201] sps_residual_coding_override_present_flag equal to 1 specifies that slice_ts_residual_coding_disabled_flag is present in the slice header referencing the SPS. sps_residual_coding_override_present_flag equal to 0 specifies that ts_residual_coding_disabled_flag is not present in the slice header referencing the SPS. When not present, the default value of sps_residual_coding_override_present_flag is equal to 0.

[0202]

[0203] In other examples, the changes may be as follows:

[0204] <change>

[0205] pps_residual_coding_override_present_flag equal to 1 specifies that ts_residual_coding_disabled_flag is present in the slice header referencing the PPS. pps_residual_coding_override_present_flag equal to 0 specifies that slice_ts_residual_coding_disabled_flag is not present in the slice header referencing the PPS. When not present, the default value of pps_residual_coding_override_present_flag is equal to 0.

[0206] dep_quant_info_in_ph_flag equal to 1 specifies that dependency quantization information is present in the PH syntax structure and is not present in slice headers that reference a PPS and do not contain a PH syntax structure. dep_quant_info_in_ph_flag equal to 0 specifies that dependency quantization information is not present in the PH syntax structure and may be present in slice headers that reference a PPS and do not contain a PH syntax structure.

[0207] sign_data_hiding_info_in_ph_flag equal to 1 specifies that the sign data hiding information is present in the PH syntax structure and is not present in slice headers that reference a PPS and do not contain a PH syntax structure. sign_data_hinding_info_in_ph_flag equal to 0 specifies that the sign data hiding information is not present in the PH syntax structure and may be present in slice headers that reference a PPS and do not contain a PH syntax structure.

[0208] < / change>

[0209] Another example will now be described. If the video encoder 200 does not signal DQ and SDH in the PH, the specification can be simplified to the case where signaling of the residual coding method is enabled in the PPS or SPS.

[0210] 7.3.7.1 Generic Slice Header Syntax

[0211]

[0212]

[0213] or

[0214]

[0215]

[0216] Figure 5Flowchart illustrating a technique for preventing dependency quantization and sign data hiding for a transform skip block coded with a transform residual according to the techniques of this disclosure. A video decoder 300 may receive a first slice header syntax element for a slice of video data (330). For example, the video decoder 300 may receive a slice of video data in a bitstream having a header that includes a slice_dep_quant_enabled_flag. The video decoder 300 may determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice (332). For example, the video decoder 300 may parse a syntax element in the slice header, such as a slice_dep_quant_enabled_flag, that indicates whether dependency quantization is enabled for the slice. The video decoder 300 may receive a second slice header syntax element for a slice of video data (334). For example, the video decoder 300 may receive a slice of video data in a bitstream having a header that includes a slice_sign_data_hiding_enabled_flag. The video decoder 300 may determine a second value of a second slice header syntax element for the slice, the second value indicating whether sign data hiding is enabled for the slice (336). For example, the video decoder 300 may parse a syntax element in the slice header, such as slice_sign_data_hiding_enabled_flag, that indicates whether sign data hiding is enabled for the slice.

[0217] The video decoder 300 may determine whether transform skip residual coding is disabled for the slice based on the first value and the second value (338). For example, as part of determining whether transform skip residual coding is disabled for the slice, the video decoder 300 may determine that transform skip residual coding is enabled for the slice in response to one or both of the first value indicating that dependency quantization is enabled for the slice (e.g., the first value is equal to 1) or the second value indicating that sign data hiding is enabled for the slice (e.g., the second value is equal to 1). In this example, the video decoder 300 may infer that a third slice header syntax element (e.g., slice_ts_residual_coding_disabled_flag) indicating whether transform skip residual coding is disabled for the slice is set to a value indicating that transform skip residual coding is enabled for the slice (e.g., the value is equal to 0). In some examples, in response to determining that a block of the slice is encoded in transform skip mode, the video decoder 300 may apply transform skip residual decoding to the block. In some examples, the first value is equal to 1 or the second value is equal to 1.

[0218] In some examples, as part of determining whether transform skip residual coding is disabled for the slice, the video decoder 300 may receive a third slice header syntax element (e.g., slice_ts_residual_coding_disabled_flag) indicating whether transform skip residual coding is disabled for the slice, in response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that sign data hiding is disabled for the slice. In some examples, a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice (e.g., the third value is equal to 1), and as part of decoding the slice, the video decoder 300, in response to determining that a block of the slice is encoded in transform skip mode, decodes the block using transform residual coding while avoiding use of dependency quantization and sign data hiding for the block. In some examples, the third value for the third slice header syntax element indicates that transform skip residual decoding is enabled for the slice, and wherein as part of decoding the slice, the video decoder 300 can apply transform skip residual decoding to the block in response to determining that the block of the slice is encoded in transform skip mode.

[0219] In some examples, the first value is equal to 0 (e.g., the value of slice_dep_quant_enabled_flag is equal to 0), and the second value is equal to 0 (e.g., the value of slice_sign_data_hiding_enabled_flag is equal to 0). For example, as part of determining whether transform skip residual coding is disabled for the slice, the video decoder 300 may receive a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice in response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that sign data hiding is disabled for the slice. In some examples, the third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein as part of decoding the slice, the video decoder 300, in response to determining that a block of the slice is encoded in transform skip mode, decodes the block using transform residual coding while avoiding use of dependency quantization and sign data hiding for the block.

[0220] In such examples, video decoder 300 may determine whether transform skip residual coding is disabled for the slice at least in part by parsing syntax elements in a slice header. For example, video decoder 300 may parse slice_ts_residual_coding_disabled_flag when determining whether transform skip residual coding is disabled for the slice.

[0221] Video decoder 300 may decode the slice based on these determinations (340). For example, video decoder 300 may decode the slice based on the first value, the second value, and a determination of whether transform skip residual coding is disabled. For example, if dependency quantization is enabled, if sign data hiding is enabled, or if both dependency quantization and sign data hiding are enabled, video decoder 300 may not apply transform skip residual coding.

[0222] In some examples where at least one of the first value or the second value is 1, the video decoder 300 may avoid parsing the syntax element indicating whether transform skip residual coding is disabled for the slice in the slice header based on at least one of the first value or the second value being 1. For example, the video encoder 200 may not signal the syntax element indicating whether transform skip residual coding is disabled for the slice (e.g., slice_ts_residual_coding_disabled_flag), and the video decoder 300 may infer the value of the syntax element indicating whether transform skip residual coding is disabled for the slice as indicating that transform skip residual coding is not disabled (e.g., enabled).

[0223] In some examples, when decoding the slice, the video decoder 300 may apply transform skip residual coding to the slice. In some examples, when decoding the slice, the video decoder 300 may avoid applying transform residual decoding to the slice. In some examples, a first value equal to 1 indicates that dependency quantization is enabled for the slice, and a second value equal to 1 indicates that sign data hiding is enabled for the slice. In some examples, the slice includes a block, and the block is encoded using transform skip mode. In such examples, as part of decoding the slice, the video decoder 300 may use transform residual coding to decode the block while avoiding dependency quantization and sign data hiding for the block.

[0224] In some examples, the device includes a display configured to display the slice. In some examples, the device is a mobile device.

[0225] Figure 6 is a flow chart illustrating other techniques for preventing dependency quantization and sign data hiding for transform skip blocks coded using transform residuals according to techniques of this disclosure. The video encoder 200 may determine whether dependency quantization is enabled for a slice of video data (342). For example, the video encoder 200 may coordinate multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values ​​for such combinations when determining whether dependency quantization is enabled for the slice.

[0226] The video encoder 200 may determine whether to enable symbol data hiding for the slice (344). For example, the video encoder 200 may coordinate multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values ​​for such combinations when determining whether to enable symbol data hiding for the slice.

[0227] Based on the determination of whether dependency quantization is enabled for the slice or the determination of whether sign data hiding is enabled for the slice, the video encoder 200 may determine whether transform skip residual coding is disabled for the slice (346). For example, if one or both of dependency quantization or sign data hiding are enabled, the video encoder 200 may enable transform skip residual coding for the slice. The video encoder 200 may encode the slice based on these determinations (348). For example, if one or both of dependency quantization or sign data hiding are enabled, the video encoder 200 may encode the slice using transform skip residual coding.

[0228] Determining whether transform skip residual coding is disabled for the slice includes determining transform skip residual coding is enabled for the slice in response to one or both of determining that dependency quantization is enabled for the slice or determining that sign data hiding is enabled for the slice.

[0229] In some examples, video encoder 200 may refrain from signaling a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice. In some examples, video encoder 200 may apply transform skip residual decoding to the block in response to determining that the block of the slice is encoded in transform skip mode.

[0230] In some examples, the video encoder 200 may signal a first slice header syntax element for the slice, wherein the first syntax element indicates whether dependency quantization is enabled for the slice. In some examples, the video encoder 200 may signal a second slice header syntax element for the slice, wherein the second value indicates whether sign data hiding is enabled for the slice, and wherein the first value is equal to 1 or the second value is equal to 1.

[0231] In some examples, in response to determining that dependency quantization is disabled for the slice and determining that sign data hiding is disabled for the slice, video encoder 200 may signal a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice. In some examples, a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and video encoder 200 may refrain from using dependency quantization and sign data hiding for the block in response to determining that encoding of the block of the slice is coded in transform skip mode. In some examples, video encoder 200 may apply transform skip residual coding to the block in response to determining that encoding of the block of the slice is coded in transform skip mode.

[0232] Figure 7 1 is a flowchart illustrating an exemplary method for encoding a current block. The current block may include a current CU. Although with respect to the video encoder 200 ( Figure 1 and Figure 3 ) is described, but it should be understood that other devices may be configured to perform similar Figure 7 method of method.

[0233] In this example, the video encoder 200 first predicts a current block (350). For example, the video encoder 200 may form a prediction block for the current block. The video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, the video encoder 200 may calculate the difference between the original, unencoded block of the current block and the prediction block. The video encoder 200 may then transform and quantize the residual block (354). For example, the video encoder 200 may: determine a first value of a first slice header syntax element of a slice of video data, the first value indicating whether dependency quantization is enabled for the slice; determine a second value of a second slice header syntax element of the slice, the second value indicating whether sign data hiding is enabled for the slice; and determine whether transform skip residual coding is disabled for the slice. In some examples, as explained above, the transform process may be skipped. Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or after the scan, the video encoder 200 may entropy encode the transform coefficients (358). For example, video encoder 200 may encode the transform coefficients using CAVLC or CABAC.Video encoder 200 may then output entropy-encoded data for the block (360).

[0234] Figure 8 is a flow chart illustrating an exemplary method for decoding a current block of video data. The current block may include a current CU. Although with respect to the video decoder 300 ( Figure 1 and Figure 4 ) is described, but it should be understood that other devices may be configured to perform similar Figure 8 method of method.

[0235] The video decoder 300 may receive entropy-encoded data for a current block, such as entropy-encoded prediction information and entropy-encoded data of transform coefficients for a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy-encoded data to determine prediction information for the current block and reproduce transform coefficients for the residual block (372). The video decoder 300 may predict the current block (374), for example, using intra-frame or inter-frame prediction as indicated by the prediction information for the current block, to calculate a prediction block for the current block. The video decoder 300 may then inverse scan the reproduced transform coefficients (376) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize the transform coefficients and apply an inverse transform to the transform coefficients to produce a residual block (378). For example, the video decoder 300 may: determine a first value of a first slice header syntax element of a slice of video data, the first value indicating whether dependency quantization is enabled for the slice; determine a second value of a second slice header syntax element of the slice, the second value indicating whether symbol data hiding is enabled for the slice; and determine whether transform skip residual decoding is disabled for the slice. In some examples, as explained above, the transform process can be skipped. The video decoder 300 may finally decode the current block by combining the prediction block with the residual block (380). In some examples, decoding may be based on the determination of the first value, the second value, and whether transform skip residual decoding is disabled.

[0236] Through the techniques of this disclosure, it is possible to prevent originally lossless coding from becoming lossy by disabling the use of lossy coding tools (such as DQ and SDH) when transform skip residual coding is enabled.

[0237] This disclosure includes the following examples.

[0238] Clause 1A. A method of coding video data, the method comprising: determining that a block of the video data is a transform skip block; coding the transform skip block using transform residual coding; and avoiding use of dependency quantization and sign data hiding.

[0239] Clause 2A. The method of clause 1A, further comprising: determining whether slice_ts_residual_coding_disabled_flag is equal to 1; and based on slice_ts_residual_coding_disabled_flag being equal to 1, refraining from signaling ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag or inferring that both ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag are equal to 0.

[0240] Clause 3A. The method of clause 1A, further comprising: determining whether slice_dep_quant_enabled_flag or slice_sign_data_hiding_enabled_flag or both slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag are equal to 1; and based on slice_dep_quant_enabled_flag or slice_sign_data_hiding_enabled_flag or both slice_dep_quant_enabled_flag and slice_sign_data_hiding_enabled_flag being equal to 1, refraining from signaling

[0241] slice_ts_residual_coding_disabled_flag or inferred slice_ts_residual_coding_disabled_flag is 0.

[0242] Clause 4A. The method of clause 1A, further comprising: determining values ​​for ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag; and refraining from signaling slice_ts_residual_coding_disabled_flag or inferring a value for slice_ts_residual_coding_disabled_flag based on the values ​​of ph_dep_quant_enabled_flag and pic_sign_data_hiding_enabled_flag.

[0243] Clause 5A. The method of clause 1A, further comprising: determining a value of slice_ts_residual_coding_disabled_flag; and avoiding use of dependency quantization and sign data hiding based on the value of slice_ts_residual_coding_disabled_flag.

[0244] Clause 6A. The method of any of clauses 1A to 5A, wherein deciphering comprises decoding.

[0245] Clause 7A. The method of any of clauses 1A to 6A, wherein decoding comprises encoding.

[0246] Clause 8A. An apparatus for coding video data, the apparatus comprising one or more means for performing the method of any of Clauses 1A to 7A.

[0247] Clause 9A. The apparatus of Clause 8A, wherein the one or more components comprise one or more processors implemented in circuitry.

[0248] Clause 10A. The apparatus of any of clauses 8A and 9A, further comprising a memory for storing video data.

[0249] Clause 11A. The apparatus of any of clauses 8A to 10A, further comprising a display configured to display the decoded video data.

[0250] Clause 12A. The device of any of clauses 8A to 11A, wherein the device comprises one or more of: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0251] Clause 13A. The apparatus of any of clauses 8A to 12A, wherein the apparatus comprises a video decoder.

[0252] Clause 14A. The apparatus of any of clauses 8A to 13A, wherein the apparatus comprises a video encoder.

[0253] Clause 15A. A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to perform the method of any of clauses 1A to 7A.

[0254] Clause 16A. An apparatus for encoding video data, the apparatus comprising:

[0255] Means for determining that the block of video data is a transform skip block; means for coding the transform skip block using transform residual coding; and means for avoiding the use of dependency quantization and sign data hiding.

[0256] Clause 17A. A method of decoding, the method comprising: determining, based on a syntax element in a sequence parameter set, that a slice level flag is present; and determining, based on the slice level flag, to enable transform residual coding for blocks of the slice.

[0257] Clause 18A. A method of decoding, the method comprising: determining, based on a syntax element in a picture parameter set, that a slice level flag is present; and determining, based on the slice level flag, that transform residual coding is enabled for blocks of the slice.

[0258] Clause 19A. A method of decoding, the method comprising: determining, based on a syntax element in a sequence parameter set, that a picture header level flag is present; and determining, based on the picture header level flag, to enable dependent quantization for a current picture.

[0259] Clause 20A. A method of decoding, the method comprising: determining, based on a syntax element in a picture parameter set, that a picture header level flag is present; and determining, based on the picture header level flag, to enable dependent quantization for a current picture.

[0260] Clause 21A. A method of decoding, the method comprising: determining, based on a syntax element in a sequence parameter set, that a picture header level flag is present; and determining, based on the picture header level flag, that sign bit hiding is enabled for a current picture.

[0261] Clause 22A. A method of decoding, the method comprising: determining, based on a syntax element in a picture parameter set, that a picture header level flag is present; and determining, based on the picture header level flag, that sign bit hiding is enabled for a current picture.

[0262] Clause 23A. A method comprising any combination of clauses 17A to 22A.

[0263] Clause 24A. An apparatus for decoding video data, the apparatus comprising one or more means for performing the method of any of Clauses 17A to 23A.

[0264] Clause 25A. The apparatus of Clause 24A, wherein the one or more components comprise one or more processors implemented in circuitry.

[0265] Clause 26A. The apparatus of clauses 24A and 25A, further comprising a memory for storing video data.

[0266] Clause 27A. The apparatus of any of Clauses 24A to 26A, further comprising a display configured to display the decoded video data.

[0267] Clause 28A. The device of any of clauses 24A to 27A, wherein the device comprises one or more of: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0268] Clause 29A. The apparatus of any of clauses 24A to 28A, wherein the apparatus comprises a video decoder.

[0269] Clause 1B. A method for decoding video data, the method comprising: receiving a first slice header syntax element for a slice of the video data; determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receiving a second slice header syntax element for the slice of the video data; determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determining whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decoding the slice based on the determination.

[0270] Clause 2B. A method according to clause 1B, wherein determining whether transform skip residual decoding is disabled for the slice includes determining that transform skip residual decoding is enabled for the slice in response to one or both of the first value indicating that dependency quantization is enabled for the slice or the second value indicating that symbol data hiding is enabled for the slice.

[0271] Clause 3B. The method of clause 2B, wherein determining that transform skip residual coding is enabled for the slice comprises inferring that a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice is set to a value indicating that transform skip residual coding is enabled for the slice.

[0272] Clause 4B. The method of clause 3B, wherein decoding the slice comprises, in response to determining that a block of the slice is encoded in transform skip mode, applying transform skip residual decoding to the block.

[0273] Clause 5B. The method of any combination of clauses 2B to 4B, wherein the first value is equal to 1, or the second value is equal to 1.

[0274] Clause 6B. A method according to clause 1B, wherein determining whether transform skip residual decoding is disabled for the slice includes: in response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that symbol data hiding is disabled for the slice, receiving a third slice header syntax element indicating whether transform skip residual decoding is disabled for the slice.

[0275] Clause 7B. A method according to clause 6B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is disabled for the slice, and wherein decoding the slice includes: in response to determining that a block of the slice is encoded in transform skip mode, decoding the block using transform residual decoding while avoiding use of dependency quantization and sign data hiding for the block.

[0276] Clause 8B. A method according to clause 6B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is enabled for the slice, and wherein decoding the slice includes: in response to determining that a block of the slice is encoded in transform skip mode, applying transform skip residual decoding to the block.

[0277] Item 9B. A device for decoding video data, the device comprising: a memory configured to store the video data; and one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: receive a first slice header syntax element for a slice of the video data; determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decode the slice based on the determination.

[0278] Clause 10B. A method according to clause 9B, wherein as part of determining that transform skip residual decoding is enabled for the slice, the one or more processors are configured to: determine that transform skip residual decoding is enabled for the slice in response to one or both of the first value indicating that dependency quantization is enabled for the slice or the second value indicating that symbol data hiding is enabled for the slice.

[0279] Clause 11B. A method according to clause 10B, wherein as part of determining whether transform skip residual decoding is enabled for the slice, the one or more processors are configured to: infer that a third slice header syntax element indicating whether transform skip residual decoding is disabled for the slice is set to a value indicating that transform skip residual decoding is enabled for the slice.

[0280] Clause 12B. The method of clause 11B, wherein as part of decoding the slice, the one or more processors are configured to: in response to determining that a block of the slice is encoded in transform skip mode, apply transform skip residual decoding to the block.

[0281] Clause 13B. The apparatus of any combination of clauses 10B to 12B, wherein the first value is equal to 1, or the second value is equal to 1.

[0282] Clause 14B. A method according to clause 9B, wherein as part of determining whether transform skip residual decoding is disabled for the slice, the one or more processors are configured to: in response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that symbol data hiding is disabled for the slice, receive a third slice header syntax element indicating whether transform skip residual decoding is disabled for the slice.

[0283] Clause 15B. A method according to clause 14B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is disabled for the slice, and wherein as part of decoding the slice, the first one or more processors are configured to: in response to determining that a block of the slice is encoded in transform skip mode, decode the block using transform residual decoding while avoiding use of dependency quantization and sign data hiding for the block.

[0284] Clause 16B. A method according to clause 14B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is enabled for the slice, and wherein as part of decoding the slice, the one or more processors are configured to: in response to determining that a block of the slice is encoded in transform skip mode, apply transform skip residual decoding to the block.

[0285] Clause 17B. The apparatus of any combination of clauses 9B to 16B, further comprising: a display coupled to the one or more processors, the display configured to display the slice.

[0286] Clause 18B. The device of any combination of clauses 9B to 17B, wherein the device comprises a mobile device.

[0287] Clause 19B. A non-transitory computer-readable storage medium having instructions stored thereon, the instructions, when executed, causing one or more processors to: receive a first slice header syntax element for a slice of video data; determine a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receive a second slice header syntax element for the slice of the video data; determine a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and decode the slice based on the determination.

[0288] Clause 20B. An apparatus for decoding video data, the apparatus comprising: means for receiving a first slice header syntax element for a slice of the video data; means for determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; means for receiving a second slice header syntax element for the slice of the video data; means for determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; means for determining whether transform skip residual decoding is disabled for the slice based on the first value and the second value; and means for decoding the slice based on the determination.

[0289] Clause 21B. A method for encoding video data, the method comprising: determining whether dependency quantization is enabled for a slice of the video data; determining whether symbol data hiding is enabled for the slice; determining whether transform skip residual decoding is disabled for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether symbol data hiding is enabled for the slice; and encoding the slice based on the determination.

[0290] Clause 22B. The method of clause 21B, wherein determining whether transform skip residual coding is disabled for the slice comprises determining that transform skip residual coding is enabled for the slice in response to one or both of determining that dependency quantization is enabled for the slice or determining that sign data hiding is enabled for the slice.

[0291] Clause 23B. The method of clause 22B, further comprising: refraining from signaling a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice.

[0292] Clause 24B. The method of clause 23B, wherein encoding the slice comprises applying transform skip residual decoding to a block of the slice in response to determining that the block is encoded in transform skip mode.

[0293] Clause 25B. The method according to clause 22B further comprising: signaling a first slice header syntax element for the slice, wherein the first syntax element indicates whether dependency quantization is enabled for the slice; and signaling a second slice header syntax element for the slice, wherein the second value indicates whether symbol data hiding is enabled for the slice, wherein the first value is equal to 1, or the second value is equal to 1.

[0294] Clause 26B. The method of clause 21B, further comprising: in response to determining that dependency quantization is disabled for the slice and determining that symbol data hiding is disabled for the slice, signaling a third slice header syntax element indicating whether transform skip residual decoding is disabled for the slice.

[0295] Clause 27B. A method according to clause 26B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is disabled for the slice, and wherein encoding the slice includes: in response to determining that encoding a block of the slice is to be encoded in transform skip mode, avoiding using dependency quantization and symbol data hiding for the block.

[0296] Clause 28B. The method of Clause 27B, further comprising applying transform skip residual coding to the block of the slice in response to determining that the block is encoded in transform skip mode.

[0297] Item 29B. A device for decoding video data, the device comprising: a memory configured to store the video data; and one or more processors implemented in a circuit and coupled to the memory, the one or more processors configured to: determine whether dependency quantization is enabled for a slice of the video data; determine whether symbol data hiding is enabled for the slice; determine whether transform skip residual decoding is disabled for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether symbol data hiding is enabled for the slice; and encode the slice based on the determination.

[0298] Clause 30B. A method according to clause 29B, wherein as part of determining whether transform skip residual decoding is disabled for the slice, the one or more processors are configured to: determine to enable transform skip residual decoding for the slice in response to one or both of determining to enable dependency quantization for the slice or determining to enable symbol data hiding for the slice.

[0299] Clause 31B. The method of clause 29B, wherein the one or more processors are further configured to refrain from signaling a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice.

[0300] Clause 32B. The method of clause 31B, wherein as part of encoding the slice, the one or more processors are configured to: apply transform skip residual coding to a block of the slice in response to determining that the block is to be encoded in transform skip mode.

[0301] Clause 33B. A method according to clause 30B, wherein the one or more processors are further configured to: signal a first slice header syntax element for the slice, wherein the first syntax element indicates whether dependency quantization is enabled for the slice; and signal a second slice header syntax element for the slice, wherein the second value indicates whether symbol data hiding is enabled for the slice, wherein the first value is equal to 1, or the second value is equal to 1.

[0302] Clause 34B. A method according to clause 28B, wherein the one or more processors are further configured to: in response to determining that dependency quantization is disabled for the slice and determining that symbol data hiding is disabled for the slice, signal a third slice header syntax element indicating whether transform skip residual decoding is disabled for the slice.

[0303] Clause 34B. A method according to clause 33B, wherein the third value for the third slice header syntax element indicates that transform skip residual decoding is disabled for the slice, and wherein as part of encoding the slice, the first one or more processors are configured to: in response to determining that encoding a block of the slice is to be encoded in transform skip mode, avoid using dependency quantization and symbol data hiding for the block.

[0304] Clause 35B. The method of clause 34B, wherein the one or more processors are further configured to apply transform skip residual coding to a block of the slice in response to determining that the block is encoded in transform skip mode.

[0305] Clause 36B. The method of Clause 29B, further comprising: a camera coupled to the one or more processors, the camera configured to capture the video data.

[0306] Clause 37B. The method of clause 28B, wherein the device comprises a mobile device.

[0307] Clause 1C. A method comprising any combination of clauses 1A-7A, 17A-22A, 1B-8B, or 21B-28B.

[0308] Clause 2C. An apparatus comprising any combination of clauses 8A-14A, 16A, 24A-29A, 9B-18B, 20B, or 29B-37B.

[0309] Clause 3C. A non-transitory computer-readable storage medium comprising any combination of clauses 15A and 19B.

[0310] It should be appreciated that, depending on the example, certain actions or events of any of the techniques described herein may be performed in a different order, may be added, combined, or excluded entirely (e.g., not all described actions or events are required to practice the technique). Furthermore, in some examples, actions or events may be performed concurrently, for example, through multithreading, interrupt handling, or execution by multiple processors, rather than sequentially.

[0311] In one or more examples, the functions described can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions can be stored as one or more instructions or codes on a computer-readable medium or sent via a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media can include computer-readable storage media (which corresponds to tangible media such as data storage media) or communication media, which includes any media that facilitates, for example, the transfer of a computer program from one place to another according to a communication protocol. Thus, computer-readable media can generally correspond to (1) non-transitory tangible computer-readable storage media, or (2) communication media (such as, a signal or carrier wave). Data storage media can be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the techniques described in this disclosure. A computer program product can include computer-readable media.

[0312] By way of example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, flash memory, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Moreover, any connection is appropriately referred to as a computer-readable medium. For example, if instructions are sent from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, then the definition of medium includes coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves. 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 rather are directed to non-temporary, tangible storage media. Disks and optical disks as used herein include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while optical discs reproduce data optically with the aid of lasers. The above combinations should also be included within the scope of computer-readable media.

[0313] 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 circuit systems. Thus, as used herein, the terms "processor" and "processing circuitry" may refer to any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. Additionally, 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. Furthermore, the techniques may be fully implemented in one or more circuits or logic elements.

[0314] The techniques of this disclosure can be implemented in a wide variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but they do not necessarily need to be implemented by different hardware units. Rather, as described above, the various units can 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.

[0315] 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 slice header syntax element for a slice of the video data; determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receiving a second slice header syntax element for the slice of the video data; determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determining whether to disable transform skip residual coding for the slice based on the first value and the second value; as well as The slice is decoded based on the determination.

2. The method of claim 1 , wherein determining whether transform skip residual coding is disabled for the slice comprises determining that transform skip residual coding is enabled for the slice in response to one or both of the first value indicating that dependency quantization is enabled for the slice or the second value indicating that symbol data hiding is enabled for the slice.

3. The method of claim 2 , wherein determining to enable transform skip residual coding for the slice comprises: A third slice header syntax element indicating whether transform skip residual coding is disabled for the slice is inferred to be set to a value indicating that transform skip residual coding is enabled for the slice.

4. The method of claim 3 , wherein decoding the slice comprises: In response to determining that a block of the slice is encoded in transform skip mode, transform skip residual decoding is applied to the block. The method according to claim 2 , wherein the first value is equal to 1, or the second value is equal to 1.

6. The method of claim 1 , wherein determining whether transform skip residual coding is disabled for the slice comprises: In response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that sign data hiding is disabled for the slice, receiving a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice.

7. The method of claim 6, wherein a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein decoding the slice comprises: In response to determining that a block of the slice is encoded in transform skip mode, transform residual coding is used to decode the block while avoiding dependent quantization and sign data hiding for the block.

8. The method of claim 6, wherein a third value for the third slice header syntax element indicates that transform skip residual coding is enabled for the slice, and wherein decoding the slice comprises: In response to determining that a block of the slice is encoded in transform skip mode, transform skip residual decoding is applied to the block.

9. A device for decoding video data, the device comprising: a memory configured to store the video data; as well as one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: receiving a first slice header syntax element for a slice of the video data; determining a first value for the first slice header syntax element, wherein the first value indicates whether dependency quantization is enabled for the slice; receiving a second slice header syntax element for the slice of the video data; determining a second value for the second slice header syntax element, wherein the second value indicates whether symbol data hiding is enabled for the slice; determining whether to disable transform skip residual coding for the slice based on the first value and the second value; as well as The slice is decoded based on the determination.

10. The apparatus of claim 9, wherein as part of determining to enable transform skip residual coding for the slice, the one or more processors are configured to: Enabling transform skip residual coding for the slice is determined in response to one or both of the first value indicating that dependency quantization is enabled for the slice or the second value indicating that sign data hiding is enabled for the slice.

11. The apparatus of claim 10, wherein as part of determining to enable transform skip residual coding for the slice, the one or more processors are configured to: A third slice header syntax element indicating whether transform skip residual coding is disabled for the slice is inferred to be set to a value indicating that transform skip residual coding is enabled for the slice.

12. The apparatus of claim 11 , wherein as part of decoding the slice, the one or more processors are configured to: In response to determining that a block of the slice is encoded in transform skip mode, transform skip residual decoding is applied to the block. The apparatus according to claim 10 , wherein the first value is equal to 1, or the second value is equal to 1.

14. The apparatus of claim 9, wherein as part of determining whether transform skip residual coding is disabled for the slice, the one or more processors are configured to: In response to the first value indicating that dependency quantization is disabled for the slice and the second value indicating that sign data hiding is disabled for the slice, receiving a third slice header syntax element indicating whether transform skip residual coding is disabled for the slice.

15. The apparatus of claim 14 , wherein a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein as part of decoding the slice, the one or more processors are configured to: In response to determining that a block of the slice is encoded in transform skip mode, transform residual coding is used to decode the block while avoiding dependent quantization and sign data hiding for the block.

16. The apparatus of claim 14, wherein a third value for the third slice header syntax element indicates that transform skip residual coding is enabled for the slice, and wherein as part of decoding the slice, the one or more processors are configured to: In response to determining that a block of the slice is encoded in transform skip mode, transform skip residual decoding is applied to the block.

17. The apparatus of claim 9, further comprising: A display coupled to the one or more processors, the display configured to display the slice.

18. The device of claim 9, wherein the device comprises a mobile device.

19. A method for encoding video data, the method comprising: determining whether dependent quantization is enabled for a slice of the video data; determining whether symbol data hiding is enabled for the slice; determining whether to disable transform skip residual coding for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether sign data hiding is enabled for the slice; as well as The slice is encoded based on the determination.

20. The method of claim 19, wherein determining whether transform skip residual coding is disabled for the slice comprises determining transform skip residual coding is enabled for the slice in response to one or both of determining that dependency quantization is enabled for the slice or determining that sign data hiding is enabled for the slice.

21. The method according to claim 20, further comprising: Signaling a third slice header syntax element that indicates whether transform skip residual coding is disabled for the slice is avoided.

22. The method of claim 21 , wherein encoding the slice comprises: Transform skip residual decoding is applied to the block of the slice in response to determining that the block is encoded in transform skip mode.

23. The method of claim 20, further comprising: signaling a first slice header syntax element for the slice, wherein a first value for the first slice header syntax element indicates whether dependency quantization is enabled for the slice; as well as signaling a second slice header syntax element for the slice, wherein a second value for the second slice header syntax element indicates whether symbol data hiding is enabled for the slice, The first value is equal to 1, or the second value is equal to 1.

24. The method of claim 19, further comprising: In response to determining that dependency quantization is disabled for the slice and determining that sign data hiding is disabled for the slice, a third slice header syntax element is signaled that indicates whether transform skip residual coding is disabled for the slice.

25. The method of claim 24, wherein a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein encoding the slice comprises: In response to determining that encoding a block of the slice is to be encoded in transform skip mode, using dependency quantization and sign data hiding for the block is avoided.

26. The method of claim 24, further comprising: Transform skip residual encoding is applied to the block of the slice in response to determining to encode the block in transform skip mode.

27. A device for encoding video data, the device comprising: a memory configured to store the video data; as well as one or more processors implemented in circuitry and coupled to the memory, the one or more processors configured to: determining whether dependent quantization is enabled for a slice of the video data; determining whether symbol data hiding is enabled for the slice; determining whether to disable transform skip residual coding for the slice based on the determination of whether dependency quantization is enabled for the slice or the determination of whether sign data hiding is enabled for the slice; as well as The slice is encoded based on the determination.

28. The apparatus of claim 27, wherein as part of determining whether transform skip residual coding is disabled for the slice, the one or more processors are configured to: Transform skip residual coding is determined to be enabled for the slice in response to one or both of determining that dependency quantization is enabled for the slice or determining that sign data hiding is enabled for the slice.

29. The apparatus of claim 27, wherein the one or more processors are further configured to: Signaling a third slice header syntax element that indicates whether transform skip residual coding is disabled for the slice is avoided.

30. The apparatus of claim 29, wherein as part of encoding the slice, the one or more processors are configured to: Transform skip residual encoding is applied to the block of the slice in response to determining to encode the block in transform skip mode.

31. The device of claim 28, wherein the one or more processors are further configured to: signaling a first slice header syntax element for the slice, wherein a first value for the first slice header syntax element indicates whether dependency quantization is enabled for the slice; and signaling a second slice header syntax element for the slice, wherein a second value for the second slice header syntax element indicates whether symbol data hiding is enabled for the slice, The first value is equal to 1, or the second value is equal to 1.

32. The device of claim 27, wherein the one or more processors are further configured to: In response to determining that dependency quantization is disabled for the slice and determining that sign data hiding is disabled for the slice, a third slice header syntax element is signaled that indicates whether transform skip residual coding is disabled for the slice.

33. The apparatus of claim 32, wherein a third value for the third slice header syntax element indicates that transform skip residual coding is disabled for the slice, and wherein as part of encoding the slice, the one or more processors are configured to: In response to determining that encoding a block of the slice is to be encoded in transform skip mode, using dependency quantization and sign data hiding for the block is avoided.

34. The apparatus of claim 32, wherein the one or more processors are further configured to: Transform skip residual encoding is applied to the block of the slice in response to determining to encode the block in transform skip mode.

35. The apparatus of claim 27, further comprising: A camera coupled to the one or more processors is configured to capture the video data.

36. The device of claim 27, wherein the device comprises a mobile device.

37. An apparatus for decoding video data, comprising means for performing the method according to any one of claims 1 to 8.

38. An apparatus for encoding video data, comprising means for performing the method according to any one of claims 19 to 26.

39. A computer-readable medium having program code recorded thereon, wherein the program code is executable by one or more processors to cause the processors to perform the method according to any one of claims 1 to 8.

40. A computer-readable medium having program code recorded thereon, wherein the program code is executable by one or more processors to cause the processors to perform the method according to any one of claims 19 to 26.

41. A computer program product comprising computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the method of any one of claims 1-8.

42. A computer program product comprising computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the method of any one of claims 19-26.

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