Inferring intra coding mode in BDPCM coded blocks

Abstract

Video encoders and video decoders can use intra-frame prediction and block-based delta pulse coding modulation (BDPCM) mode to decode video data. BDPCM mode can include a vertical mode and a horizontal mode. Video encoders and video decoders can be configured to align the direction of the intra-frame prediction mode with the direction of the BDPCM mode for both luminance blocks and chrominance blocks.

Description

[0001] This application claims priority to U.S. application No. 17 / 126,585, filed on December 18, 2020, which claims the benefit of U.S. Provisional Application No. 62 / 954,149, filed on December 27, 2019, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital audio recorders, digital media players, video game devices, video game consoles, cellular or satellite radiotelephones, 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-T H.263, ITU-T H.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265 / High Efficiency Video Coding (HEVC), and extensions to such standards. By implementing such video coding techniques, video devices can 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 inherent redundancy 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 divided 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 relative to reference samples in neighboring blocks in the same picture, or temporal prediction relative to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to as reference frames. Summary of the Invention

[0005] In general, the present disclosure describes techniques for block-based delta pulse coding modulation (BDPCM). In one example, the present disclosure describes an example of a method for deriving intra-prediction modes for use in conjunction with a BDPCM mode. For example, a video encoder and a video decoder may be configured to determine an intra-prediction mode for a block of video data based on the BDPCM mode of the block of video data. The video encoder and the video decoder may apply the techniques of the present disclosure to both luma blocks and chroma blocks. By determining the intra-prediction mode based on the BDPCM mode, decoding efficiency may be improved. The techniques of the present disclosure may be used in conjunction with video coding techniques using the BDPCM mode, including Versatile Video Coding (VVC).

[0006] In one example, the present disclosure describes a method for decoding video data. The method may include determining a BDPCM mode for a block of the video data, and determining an intra-prediction mode based on the BDPCM mode for the block of the video data. The method may further include decoding the block of the video data according to the BDPCM mode and the intra-prediction mode.

[0007] In another example, the present disclosure describes an apparatus configured to decode video data, the apparatus comprising a memory configured to store a block of video data, and one or more processors in communication with the memory. The one or more processors may be configured to determine a BDPCM mode for the block of video data, and to determine an intra-prediction mode based on the BDPCM mode for the block of video data. The one or more processors may be configured to decode the block of video data based on the BDPCM mode and the intra-prediction mode.

[0008] In another example, the present disclosure describes an apparatus configured to decode video data. The apparatus may include means for determining a BDPCM mode for a block of the video data, and means for determining an intra-prediction mode based on the BDPCM mode for the block of the video data. The apparatus may further include means for decoding the block of the video data based on the BDPCM mode and the intra-prediction mode.

[0009] In another example, the present disclosure describes a non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device to be configured to decode video data to determine a BDPCM mode for a block of the video data, determine an intra-prediction mode based on the BDPCM mode for the block of the video data, and decode the block of the video data according to the BDPCM mode and the intra-prediction mode.

[0010] In another example, the present disclosure describes an apparatus configured to encode video data, the apparatus comprising a memory configured to store a block of video data and one or more processors in communication with the memory. The one or more processors may be configured to determine a block-based delta pulse coding modulation (BDPCM) mode for the block of video data, determine an intra-prediction mode based on the BDPCM mode for the block of video data, and encode the block of video data according to the BDPCM mode and the intra-prediction mode.

[0011] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.

[0013] Figure 2A and Figure 2B is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure and corresponding coding tree units (CTUs).

[0014] Figure 3 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

[0015] Figure 4 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

[0016] Figure 5 is a flowchart illustrating an example video encoding method.

[0017] Figure 6 is a flow chart illustrating an example video decoding method.

[0018] Figure 7 is a flowchart illustrating another example video encoding method.

[0019] Figure 8 is a flowchart illustrating another example video decoding method. DETAILED DESCRIPTION

[0020] The present disclosure relates to techniques for block-based incremental pulse coding modulation (BDPCM). In BDPCM mode, a video decoder (e.g., a video encoder and / or a video decoder) can be configured to decode blocks of prediction residuals created using intra-frame prediction. The video decoder can apply BDPCM techniques in the horizontal direction or in the vertical direction. The present disclosure describes techniques for aligning an intra-frame prediction mode with a BDPCM mode. That is, if horizontal BDPCM is used, the intra-frame prediction mode is set to a horizontal intra-frame prediction mode. Similarly, if vertical BDPCM is used, the intra-frame prediction mode is set to a vertical intra-frame prediction mode. The alignment of the BDPCM mode with the intra-frame prediction mode described above can be applied to both luminance blocks and chrominance blocks. By aligning the BDPCM mode with the intra-frame prediction mode, decoding efficiency can be improved.

[0021] Figure 1 1 is a block diagram illustrating an example video encoding and decoding system 100 that can perform the techniques of the present disclosure. The techniques of the present disclosure are generally directed to decoding (encoding and / or decoding) video data. Generally speaking, 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.

[0022] like Figure 1 As shown, in this example, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a target device 116. In particular, source device 102 provides the video data to target device 116 via computer-readable medium 110. Source device 102 and target device 116 can include any of a wide range of devices, including desktop computers, notebook computers (i.e., laptop computers), mobile devices, tablets, set-top boxes, telephone handsets (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, etc. In some cases, source device 102 and target device 116 can be equipped for wireless communication and, therefore, can be referred to as wireless communication devices.

[0023] exist Figure 1In 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 the technology for BDPCM 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 can 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 connected to an external display device, rather than including an integrated display device.

[0024] like Figure 1 The illustrated system 100 is merely an example. In general, any digital video encoding and / or decoding device can implement the techniques used for BDPCM decoding. Source device 102 and destination device 116 are merely examples of decoding devices in which 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) of data. Thus, video encoder 200 and video decoder 300 represent examples of decoding devices, specifically, a video encoder and a video decoder, 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 a video encoding component and a video decoding component. 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.

[0025] In general, video source 104 represents a source of video data (i.e., raw, unencoded video data) and provides a sequential series of pictures (also referred to as "frames") of video data to video encoder 200, which encodes the data for the pictures. 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) to receive video from a video content provider. As a further alternative, 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 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 onto computer-readable medium 110 via output interface 108 for receipt and / or retrieval by, for example, input interface 122 of target device 116 .

[0026] Memory 106 of source device 102 and memory 120 of destination device 116 represent general-purpose memories. In some examples, memory 106, memory 120 can store raw video data, e.g., raw video from video source 104 and raw, decoded video data from video decoder 300. Additionally or alternatively, memory 106, memory 120 can store software instructions executable by, for example, video encoder 200 and video decoder 300, respectively. While memory 106 and memory 120 are shown separately from video encoder 200 and video decoder 300 in this example, it should be understood that video encoder 200 and video decoder 300 can also include internal memory for functionally similar or equivalent purposes. Furthermore, memory 106, memory 120 can store encoded video data, e.g., output from video encoder 200 and input to video decoder 300. In some examples, a portion of memory 106, memory 120 can be allocated as one or more video buffers, e.g., to store raw, decoded, and / or encoded video data.

[0027] 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 send the encoded video data directly to the target device 116 in real time, for example, via a radio frequency network or a computer-based network. The output interface 108 can modulate a transmit signal comprising the encoded video data, and the input interface 122 can demodulate the received transmit signal according to a communication standard (such as a wireless communication protocol). The communication medium can include any wireless communication medium 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 other equipment that can be used to facilitate communication from the source device 102 to the target device 116.

[0028] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, target 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, a Blu-ray disc, a DVD, a CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0029] In some examples, source device 102 may output the encoded video data to file server 114 or another intermediate storage device that may store the encoded video data generated by source device 102. Target device 116 may access the stored video data from file server 114 via streaming or downloading.

[0030] The file server 114 may be any type of server device capable of storing encoded video data and transmitting the encoded video data to the target device 116. The file server 114 may represent a network server (e.g., for a website), a server configured to provide file transfer protocol services (e.g., File Transfer Protocol (FTP) or File Delivery over Unidirectional Transport (FLUET) protocol), a content delivery network (CDN) device, a Hypertext Transfer Protocol (HTTP) server, a Multimedia Broadcast Multicast Service (MBMS) or enhanced MBMS (eMBMS) server, and / or a Network Attached Storage (NAS) device. The file server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as Dynamic Adaptive Streaming over HTTP (DASH), HTTP Live Streaming (HLS), Real Time Streaming Protocol (RTSP), HTTP Dynamic Streaming, etc.

[0031] The target device 116 can access the encoded video data from the file server 114 through any standard data connection, including an Internet connection. This can 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 the file server 114. The input interface 122 can be configured to operate according to any one or more of the various protocols discussed above for retrieving or receiving media data from the file server 114, or according to other such protocols for retrieving media data.

[0032] Output interface 108 and input interface 122 may represent wireless transmitters / receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of the various IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless components, output interface 108 and input interface 122 may be configured to transmit data (e.g., encoded video data) according to a cellular communication standard (e.g., 4G, 4G-LTE (Long Term Evolution), Advanced LTE, 5G, etc.). In some examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 may be configured to transmit data (e.g., encoded video data) according to other wireless standards (e.g., IEEE 802.11 specifications, IEEE 802.15 specifications (e.g., ZigBee), Bluetooth TMStandards, etc.) to transmit data (such as encoded video data). In some examples, source device 102 and / or destination device 116 may include respective system-on-chip (SoC) devices. For example, source device 102 may include a SoC device 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.

[0033] 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.

[0034] The input interface 122 of the target device 116 receives an encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, a storage device 112, a file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 and used by the video decoder 300, such as syntax elements with values ​​describing characteristics of video blocks or other decoded units (e.g., slices, pictures, groups of pictures, sequences, etc.) and / or processing of video blocks or other coded units. The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0035] Although not in Figure 1 , but in some examples, the video encoder 200 and the video decoder 300 may each be integrated with an audio encoder and / or an audio decoder and may include appropriate MUX-DEMUX units or other hardware and / or software to process the multiplexed streams of both audio and video included 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).

[0036] 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, one of which can be integrated as part of a combined encoder / decoder (CODEC) in the respective device. The 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.

[0037] The video encoder 200 and the video decoder 300 may operate in accordance with a video coding standard, such as ITU-T H.265, also known as High Efficiency Video Coding (HEVC), or extensions thereof, such as multi-view and / or scalable video coding extensions. Alternatively, the video encoder 200 and the video decoder 300 may operate in accordance with other proprietary or industry standards, such as the Joint Exploration Test Model (JEM) or ITU-T H.266, also known as Versatile Video Coding (VVC). The latest draft of the VVC standard is described in Bross et al., “Versatile Video Coding (Draft 7)”, Joint Video Experts Group (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11, 16th Meeting: Geneva, Switzerland, October 1-11, 2019, JVET-P2001-v14 (hereinafter referred to as “VVC Draft 7”). However, the techniques of this disclosure are not limited to any particular coding standard.

[0038] In general, the video encoder 200 and the video decoder 300 can perform block-based decoding of a picture. The term "block" generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and / or decoding process). For example, a block can include a two-dimensional matrix of samples of luma and / or chroma data. In general, the video encoder 200 and the video decoder 300 can decode video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, rather than decoding the red, green, and blue (RGB) data of samples of a picture, the video encoder 200 and the video decoder 300 can decode luma and chroma components, where the chroma components can include both red-hue and blue-hue chroma components. In some examples, the video encoder 200 converts received RGB-formatted data to a YUV representation prior to encoding, and the video decoder 300 converts the YUV representation to an RGB format. Alternatively, a pre-processing unit and a post-processing unit (not shown) can perform these conversions.

[0039] The present disclosure may generally refer to the decoding (e.g., encoding and decoding) of a picture to include the process of encoding or decoding the data of the picture. Similarly, the present disclosure may refer to the decoding of a block of a picture to include the process of encoding or decoding the data for the block, for example, 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 the division of a picture into blocks. Therefore, references to decoding a picture or block should generally be understood as referring to the decoded values ​​for the syntax elements that form the picture or block.

[0040] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video decoder (such as the video encoder 200) divides a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video decoder divides the CTU and CU into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without child nodes may be referred to as a "leaf node", and the CU of such a leaf node may include one or more PUs and / or one or more TUs. The video decoder may further divide the PU and TU. For example, in HEVC, the residual quadtree (RQT) represents the division of TUs. In HEVC, PU represents inter-frame prediction data, and TU represents residual data. The intra-predicted CU includes intra-frame prediction information, such as an intra-frame mode indication.

[0041] As another example, the video encoder 200 and the video decoder 300 can be configured to operate according to VVC. According to VVC, a video decoder (such as the video encoder 200) divides a picture into multiple coding tree units (CTUs). The video encoder 200 can divide the CTU according to a tree structure, such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure removes the concept of multiple partition types, such as the separation between CU, PU and TU of HEVC. The QTBT structure includes two levels: a first level divided according to quadtree partitioning, and a second level divided 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 the coding units (CUs).

[0042] In the MTT partitioning structure, a block can be partitioned using quadtree (QT) partitioning, binary tree (BT) partitioning, and one or more types of ternary tree (TT) (also known as ternary tree (TT)) partitioning. A ternary tree partitioning or ternary tree partitioning is a partitioning that splits a block into three sub-blocks. In some examples, a ternary tree or ternary tree partitioning divides a block into three sub-blocks without splitting the original block through the center. The partitioning types in MTT (e.g., QT, BT, and TT) can be symmetric or asymmetric.

[0043] In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma component and the chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luma component and another QTBT / MTT structure for the two chroma components (or two QTBT / MTT structures for respective chroma components).

[0044] The video encoder 200 and the video decoder 300 can be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, or other partitioning structures per HEVC. For the purpose of explanation, the technology of the present disclosure is described 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.

[0045] In some examples, a CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples for a picture having three sample arrays, or a CTB of samples for a monochrome picture or a picture coded using three separate color planes and syntax structures for coding samples. A CTB can be an NxN block of samples for some values ​​of N, such that the partitioning of components into CTBs is a partitioning. A component is an array or a single sample from one of the three arrays (luma 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 from 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 the partitioning of a CTB into a coding block is a partitioning.

[0046] Blocks (e.g., CTUs or CUs) can be grouped in various ways in a picture. For 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 that has a height equal to the height of the picture and a width specified by a syntax element (e.g., such as in a set of picture parameters). A tile row refers to a rectangular area of ​​a CTU that has a height specified by a syntax element (e.g., such as in a set of picture parameters) and a width equal to the width of the picture.

[0047] In some examples, a tile may be divided into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not divided into multiple bricks may also be referred to as a brick. However, a brick that is a true subset of a tile may not be referred to as a tile.

[0048] Tiles in a picture can also be arranged in slices. A slice can be an integer number of tiles of a picture that can be contained exclusively in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes multiple complete tiles or only a contiguous sequence of complete tiles of a tile.

[0049] This disclosure may use "NxN" and "N by N" interchangeably to refer to the sample dimensions 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. Generally speaking, 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 rows and columns. Furthermore, a CU need not necessarily have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

[0050] The video encoder 200 encodes video data representing prediction and / or residual information and other information for a CU. The prediction information indicates how to predict the CU in order to form a prediction block for the CU. The residual information typically represents the sample-by-sample difference between the samples of the CU before encoding and the prediction block.

[0051] To predict a CU, the video encoder 200 may typically form a prediction block for the CU through inter-frame prediction or intra-frame prediction. Inter-frame prediction typically refers to predicting a CU from data of a previously decoded picture, while intra-frame prediction typically refers to predicting a CU from previously decoded data of the same picture. To perform inter-frame 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, based on the difference between the CU and the reference block. The video encoder 200 may calculate a difference metric using the sum of absolute differences (SAD), the sum of squared errors (SSD), the mean absolute difference (MAD), the mean squared error (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.

[0052] Some examples of VVC also provide an affine motion compensation mode, which can be considered an inter-frame prediction mode. In 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.

[0053] To perform intra prediction, the video encoder 200 can select an intra prediction mode to generate a prediction block. Some examples of VVC provide sixty-seven intra prediction modes, including modes for various directions as well as a planar mode and a DC mode. In general, the video encoder 200 selects an intra prediction mode that describes, for a current block (e.g., a block of a CU), neighboring samples from which the samples of the current block are predicted. Assuming that the video encoder 200 decodes CTUs and CUs in raster scan order (left to right, top to bottom), such samples may typically be above, above and to the left, or to the left of the current block in the same picture as the current block.

[0054] 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 inter-frame prediction mode to use among various available inter-frame prediction modes and motion information for the corresponding mode. For unidirectional inter-frame prediction or bidirectional inter-frame prediction, for example, the video encoder 200 may encode motion vectors using improved 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.

[0055] After prediction (such as intra-frame prediction or inter-frame prediction for a block), the video encoder 200 can 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 formed for the block using the corresponding prediction mode. The video encoder 200 can 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 can apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Alternatively, the video encoder 200 can apply a secondary transform after the first transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc. The video encoder 200 produces transform coefficients after applying the one or more transforms.

[0056] As described above, after any transform to produce transform coefficients, the video encoder 200 can perform quantization on the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to potentially reduce the amount of data used to represent the transform coefficients, providing further compression. By performing the quantization process, the video encoder 200 can reduce the bit depth associated with some or all of the transform coefficients. For example, the video encoder 200 can round down an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 can perform a bitwise right shift of the value to be quantized.

[0057] After quantization, the video encoder 200 can scan the transform coefficients to produce a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients. The scan can 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 can scan the quantized transform coefficients using a predefined scan order to produce a serialized vector, and then entropy encode the quantized transform coefficients of the vector. In other examples, the video encoder 200 can perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 can entropy encode the one-dimensional vector, for example, according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 can 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.

[0058] To perform CABAC, the video encoder 200 may assign context within a context model to a symbol to be transmitted. The context may relate to, for example, whether the value of the symbol's neighbors is zero. The probability determination may be based on the context assigned to the symbol.

[0059] The video encoder 200 may further generate syntax data (such as block-based syntax data, picture-based syntax data, and sequence-based syntax data) to the video decoder 300, for example, in a picture header, a block header, a slice header, or other syntax data (such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). The video decoder 300 may also decode such syntax data to determine how to decode the corresponding video data.

[0060] In this way, the video encoder 200 can generate a bitstream including the encoded video data, such as syntax elements describing the partitioning of a picture into blocks (e.g., CUs) and prediction and / or residual information for the blocks. Ultimately, the video decoder 300 can receive the bitstream and decode the encoded video data.

[0061] In general, the video decoder 300 performs a reciprocal process to that performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 can use CABAC to decode the values ​​of syntax elements for the bitstream in a manner substantially similar to (albeit reciprocal to) the CABAC encoding process of the video encoder 200. The syntax elements can define partitioning information for the partitioning of a picture into CTUs and the partitioning of each CTU according to a corresponding partitioning structure (such as a QTBT structure) to define CUs of the CTU. The syntax elements can further define prediction information and residual information for a block (e.g., a CU) of video data.

[0062] The residual information may be represented, for example, by quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reproduce a residual block for the block. The video decoder 300 uses the signaled prediction mode (intra-frame prediction or inter-frame prediction) and associated prediction information (e.g., motion information for inter-frame prediction) to form a prediction block for the block. The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along block boundaries.

[0063] The present disclosure may generally refer to "signaling" certain information (such as syntax elements). The term "signaling" may generally refer to communicating values ​​for syntax elements and / or other data used to decode encoded video data. That is, the video encoder 200 may signal values ​​for syntax elements in a bitstream. Generally speaking, signaling refers to generating values ​​in a bitstream. As described above, the source device 102 may transmit the bitstream to the target device 116 substantially in real time or in non-real time, such as may occur when storing syntax elements to the storage device 112 for later retrieval by the target device 116.

[0064] In accordance with the techniques of this disclosure, as will be described in more detail below, the video encoder 200 and the video decoder 300 may be configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of video data, determine an intra-prediction mode based on the BDPCM mode for the block of video data, and decode (e.g., encode or decode, respectively) the block of video data according to the BDPCM mode and the intra-prediction mode.

[0065] Figure 2A and Figure 2B 1 is a conceptual diagram illustrating an example quadtree binary tree (QTBT) structure 130 and a corresponding coding tree unit (CTU) 132. Solid lines represent quadtree splits, and dashed lines indicate binary tree splits. In each split (i.e., non-leaf) node of the binary tree, a flag is signaled to indicate which split type (i.e., horizontal or vertical) is used, where 0 indicates a horizontal split and 1 indicates a vertical split in this example. For quadtree splits, there is no need to indicate the type of split because the quadtree node splits the block horizontally and vertically into 4 sub-blocks of equal size. Therefore, the video encoder 200 can encode syntax elements (such as split information) for the region tree level (i.e., solid line) of the QTBT structure 130 and syntax elements (such as split information) for the prediction tree level (i.e., dotted line) of the QTBT structure 130, and the video decoder 300 can decode syntax elements (such as split information) for the region tree level (i.e., solid line) of the QTBT structure 130 and syntax elements (such as split information) for the prediction tree level (i.e., dotted line) of the QTBT structure 130. The video encoder 200 can encode video data (such as prediction data and transform data) for the CU represented by the terminal leaf node of the QTBT structure 130, and the video decoder 300 can decode video data (such as prediction data and transform data) for the CU represented by the terminal leaf node of the QTBT structure 130.

[0066] Generally speaking, Figure 2B The CTU 132 may be associated with parameters defining the size of blocks corresponding to nodes at the first level and at the second level 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).

[0067] 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 divided according to quadtree partitioning. That is, the node at the first level is a leaf node (no child nodes) or has four child nodes. The example of the QTBT structure 130 represents such a node as including a parent node and child nodes with solid lines for branching. If the node at the first level is not larger than the maximum allowed binary tree root node size (MaxBTSize), then the node can be further divided by its own 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 a node as having a dotted line for branching. The binary tree leaf node is called a coding unit (CU), which is used for prediction (e.g., intra-picture prediction or inter-picture prediction) and transformation without any further partitioning. As discussed above, a CU may also be referred to as a "video block" or "block."

[0068] 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 both 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. Quadtree leaf nodes can have sizes from 16x16 (i.e., MinQTSize) to 128x128 (i.e., CTU size). If the quadtree leaf 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 still the root node for the binary tree and has a binary tree depth of 0. When the binary tree depth reaches MaxBTDepth (4 in this example), further splitting is not allowed. A binary tree node with a width equal to MinBTSize (4 in this example) implies that further vertical splitting (that is, splitting of width) of the binary tree node is not allowed. Similarly, a binary tree node with a height equal to MinBTSize implies that further horizontal splitting (that is, splitting of height) of the binary tree node is not allowed. As described above, the leaf nodes of the binary tree are called CUs and are further processed according to prediction and transformation without further partitioning.

[0069] Figure 3 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Figure 3 This is provided for purposes of explanation and should not be considered limiting of the techniques broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes a video encoder 200 based on techniques of VVC (ITU-T H.266) 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.

[0070] 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, a BDPCM unit 207, and an entropy coding unit 220. Any one or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the inverse BDPCM unit 211, 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 in processing circuitry. 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 of an FPGA or an ASIC. Furthermore, video encoder 200 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0071] 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, a 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 prediction of subsequent video data performed 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, as shown, the video data memory 230 can be on-chip with other components in the video encoder 200, or off-chip relative to these components.

[0072] In the present disclosure, references to the video data memory 230 should not be construed as limited to memory internal to the video encoder 200 (unless explicitly described as such) or memory external to the video encoder 200 (unless explicitly described as such). Rather, references to the video data memory 230 should be understood as a reference memory that stores video data received by the video encoder 200 for encoding (e.g., video data for a current block to be encoded). Figure 1 The memory 106 may also provide temporary storage of outputs from the various units of the video encoder 200 .

[0073] Show Figure 3 The various units of the video encoder 200 are described 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 is pre-set for the operations that can be performed. A programmable circuit refers to a circuit that can be programmed to perform various tasks and provides 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 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 constant. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0074] 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 from programmable circuits. In an example where software executed by a programmable circuit is used to perform operations on the video encoder 200, the memory 106 ( Figure 1 ) may store instructions (eg, object code) for software that the video encoder 200 receives and executes, or another memory (not shown) within the video encoder 200 may store such instructions.

[0075] The video data memory 230 is configured to store received video data. The video encoder 200 can retrieve pictures of 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 can be the original video data to be encoded.

[0076] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units to perform video prediction according to other prediction modes. 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.

[0077] The mode selection unit 202 typically coordinates multiple encoding stages 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 some other tested combinations.

[0078] The video encoder 200 may divide the picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs into a slice. The mode selection unit 202 may divide the CTUs of the picture according to a tree structure (such as the QTBT structure or quadtree structure of HEVC described above). As described above, the video encoder 200 may form one or more CUs from the CTUs according to the tree structure. Such CUs may also be generally referred to as "video blocks" or "blocks."

[0079] In general, 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 a 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 decoded pictures stored in DPB 218). In particular, 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 errors (SSD), mean absolute difference (MAD), mean squared error (MSD), and the like. Motion estimation unit 222 may typically perform these calculations using 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 lowest value resulting from these calculations, indicating the reference block that most closely matches the current block.

[0080] Motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in a current picture. 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 values ​​for the prediction block based on one or more interpolation filters. Furthermore, for bidirectional inter prediction, motion compensation unit 224 may retrieve data for two reference blocks identified by their respective motion vectors and combine the retrieved data, for example, by sample-by-sample averaging or weighted averaging.

[0081] As another example, for intra prediction or intra prediction decoding, the intra prediction unit 226 can generate a prediction block from samples adjacent to the current block. For example, for directional mode, the intra prediction unit 226 can generally mathematically combine the values ​​of adjacent samples and pad these calculated values ​​in a direction defined across the current block to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 can calculate the average of adjacent samples to the current block and generate a prediction block to include the resulting average for each sample of the prediction block. As will be described in more detail below, in some examples, the intra prediction unit 226 can determine the intra prediction mode (e.g., intra prediction direction) based on the direction of the BDPCM mode.

[0082] 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 coded modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0083] 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, and 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 support 2Nx2N, 2NxN, Nx2N, NxN, or similar symmetric PU sizes for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

[0084] In an example where mode select unit 202 does not further split a CU into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the chroma coding block of the CU. Video encoder 200 and video decoder 300 may support CU sizes of 2Nx2N, 2NxN, or Nx2N.

[0085] For other video coding techniques (such as intra-block copy mode coding, affine mode coding, and linear model (LM) mode coding), as a few examples, the mode selection unit 202 generates a prediction block for the current block being encoded via the respective units associated with the coding technique. In some examples, such as palette mode coding, the mode selection unit 202 may not generate a prediction block, but instead generate syntax elements indicating how the block is reconstructed based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy coding unit 220 for encoding.

[0086] 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.

[0087] The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). The transform processing unit 206 can apply various transforms to the residual block to form the transform coefficient block. For example, the transform processing unit 206 can apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loewe transform (KLT), or a conceptually similar transform to the residual block. In some examples, the transform processing unit 206 can perform multiple transforms on the residual block, for example, 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.

[0088] The quantization unit 208 may quantize the transform coefficients in the transform coefficient block to produce a quantized transform coefficient block. The quantization unit 208 may quantize the transform coefficients of the transform coefficient block according to a quantization parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce a loss of information, and thus the quantized transform coefficients may have lower precision than the original transform coefficients generated by the transform processing unit 206.

[0089] In some examples, the video encoder 200 can operate according to a BDPCM mode, and the BDPCM unit 207 can perform BDPCM processing. The data path for the BDPCM mode is in Figure 3 The BDPCM mode is applied to the residual samples created by the intra prediction unit 226, although the BDPCM mode can be used with any type of residual samples. Figure 3In some examples, BDPCM mode is used with transform skip (TS) residual coding. That is, video encoder 200 bypasses transform processing unit 206 when applying BDPCM mode. As such, in some examples, BDPCM unit 207 applies BDPCM processing to residual samples in the spatial domain (e.g., as opposed to the frequency domain).

[0090] like Figure 3 As shown, in some examples, the quantization unit 208 can quantize the residual samples prior to BDPCM processing by the BDPCM unit 207. The BDPCM unit 207 can encode the quantized residual block using a horizontal prediction direction (e.g., a horizontal prediction mode) or a vertical prediction direction (e.g., a vertical prediction mode). For vertical prediction, the intra prediction unit 226 uses the pixels in the bottom row of the top neighboring block to perform vertical intra prediction on the first horizontal row of the block with unfiltered predictor samples. Similarly, for horizontal prediction, the intra prediction unit 226 uses the pixels in the rightmost column of the left neighboring block to perform horizontal intra prediction on the first vertical column of the block with unfiltered predictor samples.

[0091] The BDPCM unit 207 performs quantized level domain prediction on the quantized coefficient levels (e.g., the residual produced by the intra prediction unit 226) in the respective BDPCM directions. The video encoder 200 may signal a syntax element with a value indicating the direction (e.g., horizontal / vertical) of the BDPCM mode at the CU level. The video encoder 200 may apply BDPCM and TS residual coding to both luma blocks and chroma blocks. The inverse BDPCM unit 211 may apply the inverse process of the BDPCM unit 207 in the reconstruction loop of the video encoder 200 (e.g., see Figure 3 dashed line in the middle).

[0092] In other examples, instead of applying BDPCM, the BDPCM unit 207 can be configured to apply quantized residual domain BDPCM (also named RDPCM). The signaling and prediction directions used can be exactly the same as BPCM. The intra prediction unit 226 can perform intra prediction on the entire block by copying samples in the prediction direction (horizontal prediction or vertical prediction) to create a residual. The quantization unit 208 quantizes the residual, and the BDPCM unit 207 encodes the delta between the quantized residual and the quantized value of its predictor (horizontal or vertical).

[0093] According to the technology of the present disclosure, the video encoder 200 can be configured to determine a block-based incremental pulse coding modulation (BDPCM) mode for a block of video data. The intra-frame prediction unit 226 can determine the intra-frame prediction mode based on the BDPCM mode for the block of video data. The video encoder 200 can then encode the block of video data according to the BDPCM mode and the intra-frame prediction mode. In one example, the BDPCM mode is a horizontal BDPCM mode. In this example, the video encoder 200 can determine that the intra-frame prediction mode is a horizontal intra-frame prediction mode. In another example, the BDPCM mode is a vertical BDPCM mode. In this example, the video encoder 200 can be configured to determine that the intra-frame prediction mode is a vertical intra-frame prediction mode. The above technology can be applied to both chroma blocks and luminance blocks.

[0094] 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 from 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 from the prediction block generated by the mode selection unit 202 to generate a reconstructed block.

[0095] Filter unit 216 may perform one or more filter operations on the reconstructed block. For example, filter unit 216 may perform a deblocking operation to reduce blocking artifacts along the edges of the CU. In some examples, operations on filter unit 216 may be skipped. For example, intra prediction unit 226 may use an unfiltered block as a reference sample.

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

[0097] 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 transform 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 (which is another example of video data) on the syntax elements 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 partitioning entropy (PIPE) coding operation, an exponential 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 syntax elements are not entropy encoded.

[0098] As will be explained in more detail below, the entropy coding unit 220 may encode a first syntax element indicating a BDPCM mode (e.g., vertical or horizontal). According to one example of the present disclosure, the entropy coding unit 220 may determine a context for the syntax element indicating the BDPCM mode for the block of video data based on a color component (e.g., luma or chroma) of the block of video data, and entropy encode the syntax element indicating the BDPCM mode based on the determined context. In one example, the context is different for different color components.

[0099] The video encoder 200 may output a bitstream that includes entropy-encoded syntax elements required to reconstruct blocks of a slice or picture. In particular, the entropy encoding unit 220 may output a bitstream.

[0100] The operations described above are described with respect to blocks. Such descriptions should be understood as operations on luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding blocks and chroma coding blocks are the luma components and chroma components of a CU. In some examples, the luma coding blocks and chroma coding blocks are the luma components and chroma components of a PU.

[0101] In some examples, operations performed with respect to luma coding blocks do not need to be repeated for chroma coding blocks. For example, operations for identifying a motion vector (MV) and reference picture for a chroma coding block do not need to be repeated for identifying the MV and reference picture for a chroma block. Instead, the MV for 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 and chroma coding blocks.

[0102] Video encoder 200 represents an example of a device configured to encode video data, the device including a memory configured to store the video data and one or more processing units implemented in circuitry and configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of the video data, determine an intra-prediction mode based on the BDPCM mode for the block of the video data, and encode the block of the video data according to the BDPCM mode and the intra-prediction mode.

[0103] 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 purposes of explanation and is not intended to limit the techniques broadly exemplified and described in this disclosure. For purposes of explanation, this disclosure describes the video decoder 300 based on techniques of VVC (ITU-T H.266) 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.

[0104] 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 BDPCM unit 307, 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 circuitry. 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 in an FPGA or an ASIC. Furthermore, video decoder 300 may include additional or alternative processors or processing circuitry to perform these and other functions.

[0105] 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 to perform prediction according to other prediction modes. For 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.

[0106] The CPB memory 320 may store video data (such as an encoded video bitstream) to be decoded by the components of the video decoder 300. The video data stored in the CPB memory 320 may be, for example, a video encoded bitstream received from the computer readable medium 110 ( Figure 1 ). CPB memory 320 may include a CPB that stores coded video data (e.g., syntax elements) from a coded video bitstream. Furthermore, CPB 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 of the coded video bitstream. CPB memory 320 and DPB 314 may be formed using 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 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 these components.

[0107] Additionally or alternatively, in some examples, video decoder 300 may retrieve the video from memory 120 ( Figure 1 ) to retrieve the decoded video data. That is, memory 120 may store data along with CPB memory 320 as discussed above. Similarly, when some or all of the functionality of video decoder 300 is implemented in software to be executed by processing circuitry of video decoder 300, memory 120 may store instructions to be executed by video decoder 300.

[0108] Show Figure 4 Various units 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 3Similarly, a fixed-function circuit refers to a circuit that provides a specific function and is pre-set for the operations that can be performed. A programmable circuit refers to a circuit that can be programmed to perform various tasks and provides flexible functionality in the operations that can be performed. For example, a programmable circuit can execute software or firmware that causes the programmable circuit to operate in a manner defined by the instructions of the software or firmware. A fixed-function circuit 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 constant. In some examples, one or more of the units can be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units can be integrated circuits.

[0109] The video decoder 300 may include an ALU, an EFU, digital circuits, analog circuits, and / or a programmable core formed from programmable circuits. In an example where operations on the video decoder 300 are performed by software on the programmable circuits, on-chip memory or off-chip memory may store instructions (e.g., object code) of the software that the video decoder 300 receives and executes.

[0110] The entropy decoding unit 302 may receive the encoded video data from the CPB 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.

[0111] In general, the video decoder 300 reconstructs a picture on a block-by-block basis. The video decoder 300 may perform a reconstruction operation on each block individually (where the block currently being reconstructed (ie, decoded) may be referred to as the "current block").

[0112] The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of a quantized transform coefficient block and transform information such as a quantization parameter (QP) and / or a transform mode indication. In some examples, the video decoder 300 may operate according to a BDPCM mode, and the inverse BDPCM unit 307 may perform BDPCM processing. The data path for the BDPCM mode is in Figure 4 The BDPCM mode is applied to the coefficients output from the entropy decoding unit 302. Figure 4In some examples, BDPCM mode is used with transform skip (TS) residual decoding. That is, the video decoder 300 will bypass the inverse transform processing unit 308 when applying BDPCM mode. As such, in some examples, the inverse BDPCM unit 307 applies BDPCM processing to coefficients in the spatial domain (e.g., as opposed to the frequency domain). The inverse BDPCM unit 307 applies the above-described BDPCM processing to the coefficients in the spatial domain (e.g., as opposed to the frequency domain). Figure 3 The reverse process of the BDPCM process described.

[0113] The inverse BDPCM unit 307 performs quantized level domain prediction on the quantized coefficient levels (e.g., coefficients produced by the entropy decoding unit 302) in respective BDPCM directions. The video encoder 200 may signal a syntax element having a value indicating the direction (e.g., horizontal / vertical) of the BDPCM mode at the CU level. The video decoder may apply BDPCM and TS residual coding to both luma blocks and chroma blocks according to the mode indicated by the syntax element. In some examples, instead of applying BDPCM, the inverse BDPCM unit 307 may be configured to apply quantized residual domain BDPCM (also named RDPCM), as described above with reference to Figure 3 described.

[0114] According to the technology of the present disclosure, the video decoder 300 can be configured to determine a block-based incremental pulse coding modulation (BDPCM) mode for a block of video data. The intra-frame prediction unit 318 can determine the intra-frame prediction mode based on the BDPCM mode for the block of video data. The video decoder 300 can then decode the block of video data according to the BDPCM mode and the intra-frame prediction mode. In one example, the BDPCM mode is a horizontal BDPCM mode. In this example, the video decoder 300 can determine that the intra-frame prediction mode is a horizontal intra-frame prediction mode. In another example, the BDPCM mode is a vertical BDPCM mode. In this example, the video decoder 300 can be configured to determine that the intra-frame prediction mode is a vertical intra-frame prediction mode. The above technology can be applied to both chroma blocks and luminance blocks.

[0115] As will be explained in more detail below, the entropy decoding unit 302 may decode a first syntax element indicating a BDPCM mode (e.g., vertical or horizontal). According to one example of the present disclosure, the entropy decoding unit 302 may determine a context for the syntax element indicating the BDPCM mode for the block of video data based on a color component (e.g., luma or chroma) of the block of video data, and entropy decode the syntax element indicating the BDPCM mode based on the determined context. In one example, the context is different for different color components.

[0116] The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine the degree of quantization and, likewise, the degree of inverse quantization to apply to the inverse quantization unit 306. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block comprising the transform coefficients.

[0117] After inverse quantization unit 306 forms a transform coefficient block, inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loewe transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.

[0118] 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 a prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which to retrieve the reference block, and a motion vector that identifies the position of the reference block in the reference picture relative to the position of the current block in the current picture. Motion compensation unit 316 may generally generate a prediction block in a manner substantially similar to that described with respect to motion compensation unit 224 ( Figure 3 ) to perform the inter-frame prediction process in the manner described.

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

[0120] 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.

[0121] The filter unit 312 may perform one or more filter operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along the edges of the reconstructed block. The operations of the filter unit 312 may not necessarily be performed in all examples. For example, the intra prediction unit 318 may use an unfiltered block as a reference sample.

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

[0123] In this manner, the video decoder 300 represents an example of a video decoding device that includes a memory configured to store video data and one or more processing units implemented in circuitry and configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of video data, determine an intra-prediction mode based on the BDPCM mode for the block of video data, and decode the block of video data according to the BDPCM mode and the intra-prediction mode.

[0124] As described above, the techniques of the present disclosure are related to BDPCM decoding for VVC. The corresponding entropy encoding process (which is the reverse process of entropy decoding) is also part of the present disclosure (for example, the video decoder 300 can perform the reciprocal process of the operation described in this disclosure with respect to the video encoder 200). The techniques of the present disclosure can be applied to video codec operations similar to any video codec in current video codecs, such as extensions to High Efficiency Video Coding (HEVC), coding tools for Versatile Video Coding (VVC), and / or other future video coding standards.

[0125] The BDPCM mode is proposed for VVC development in VVC draft 6. The BDPCM mode utilizes horizontal prediction or vertical prediction of intra samples combined with DPCM decoding. In some examples, BDPCM decoding can be used with transform skip (TS) residual decoding. That is, the transform process is skipped for BDPCM decoded blocks. In one example, reference Figure 3 , the BDPCM mode is applied to the residual samples created by the intra prediction unit 226, although the BDPCM mode can be used with any type of residual samples. As such, in some examples, the BDPCM unit 207 applies BDPCM processing to the residual samples in the spatial domain (e.g., as opposed to the frequency domain).

[0126] In some examples, the quantization unit 208 can quantize the residual samples prior to BDPCM processing by the BDPCM unit 207. The BDPCM unit 207 can encode the quantized residual block using a horizontal prediction direction (e.g., a horizontal prediction mode) or a vertical prediction direction (e.g., a vertical prediction mode). For vertical prediction, the intra prediction unit 226 uses the bottom row of pixels of the top neighboring block to perform vertical intra prediction on the first horizontal row of the block with unfiltered predictor samples. Similarly, for horizontal prediction, the intra prediction unit 226 uses the rightmost column of pixels of the left neighboring block to perform horizontal intra prediction on the first vertical column of the block with unfiltered predictor samples.

[0127] The BDPCM unit 207 performs quantized level domain prediction on the quantized coefficient levels in the respective BDPCM directions (e.g., the residuals produced by the intra prediction unit 226). The video encoder 200 may signal a syntax element with a value indicating the direction (e.g., horizontal / vertical) of the BDPCM mode at the CU level. The video encoder 200 may apply BDPCM and TS residual coding to both luma blocks and chroma blocks. The inverse BDPCM unit 211 may apply the inverse process of the BDPCM unit 207 in the reconstruction loop of the video encoder 200 (e.g., see Figure 3 dashed line in the middle).

[0128] In other examples, instead of applying BDPCM, the BDPCM unit 207 can be configured to apply quantized residual domain BDPCM (also named RDPCM). The signaling and prediction directions used can be exactly the same as BPCM. The intra prediction unit 226 can perform intra prediction on the entire block by copying samples in the prediction direction (horizontal prediction or vertical prediction) to create a residual. The quantization unit 208 quantizes the residual, and the BDPCM unit 207 encodes the delta between the quantized residual and the quantized value of its predictor (horizontal or vertical).

[0129] In VVC draft 7, the BDPCM mode has two modes: vertical and horizontal. In some examples of VVC, the intra prediction mode is separate from the BDPCM mode and can be one of 66 different modes (e.g., planar, DC, horizontal, vertical, or angular). The present disclosure proposes aligning the intra prediction mode with the corresponding BDPCM mode for both the luma and chroma blocks of the video data. Aligning the intra prediction mode with the BDPCM mode can improve the decoding efficiency for some pictures of the video data.

[0130] In a first example of the present disclosure, the horizontal BDPCM mode is aligned with the horizontal intra-frame prediction direction (e.g., intra-frame angle 18) for both the luminance block and the chrominance block. Similarly, the vertical BDPCM mode is aligned with the vertical intra-frame prediction direction (e.g., intra-frame angle 50) for both the luminance block and the chrominance block. The video encoder 200 and the video decoder 300 can be configured to add the aligned intra-frame prediction mode for the BDPCM decoded block to the most probable mode (MPM) list. In other examples, the video encoder 200 and the video decoder 300 can use a planar mode or DC mode with a BDCPM decoded block. The video encoder 200 and the video decoder 300 can then use the intra-frame prediction mode in the MPM list to derive the intra-frame prediction mode for subsequently decoded blocks. These modes can be used to derive the most probable mode (MPM) list for future decoded blocks.

[0131] In the context of the present disclosure, aligning the modes means that if the BDPCM mode is a horizontal mode, the video encoder 200 and the video decoder 300 can be configured to set the intra prediction mode for the block to a horizontal intra prediction mode. Similarly, if the BDPCM mode is a vertical mode, the video encoder 200 and the video decoder 300 can be configured to set the intra prediction mode for the block to a vertical intra prediction mode. Such alignment can provide additional decoding gain. This alignment between the BDPCM mode and the intra prediction mode modifies the MPM list so that future BDPCM decoded blocks use either a horizontal mode or a vertical mode for the intra prediction mode. The video decoder 300 can determine the intra prediction mode based on a signaled BDPCM index (e.g., a syntax element indicating the direction of the BDPCM mode).

[0132] In a second example of the present disclosure, a context-adaptive binary arithmetic coding (CABAC) engine for BDPCM (e.g., Figure 3 The entropy coding unit 220 or Figure 4 The context derivation process of the entropy decoding unit 302 is changed relative to VVC draft 7. According to one example of the present disclosure, the video encoder 200 and the video decoder 300 decode the syntax element indicating the BDPCM mode (e.g., horizontal mode or vertical mode) based on block level information.

[0133] In one example, the video encoder 200 and the video decoder 300 can be configured to use separate contexts for syntax elements indicating BDPCM modes for luma color components and chroma color components. For example, if the current block is a luma block, the video encoder 200 and the video decoder 300 can use a first context set (e.g., context index 1 and context index 2) to decode syntax elements indicating vertical BDPCM mode and horizontal BDPCM mode, respectively. If the current block is a chroma block, the video encoder 200 and the video decoder 300 can use a second context set (e.g., context index 3 and context index 4) to decode syntax elements indicating vertical BDPCM mode and horizontal BDPCM mode, respectively. The first context set can be different from the second context set.

[0134] In a third example of the present disclosure, the mode alignment and context techniques described above may be used with conventional residual coding (also known as transform residual coding). That is, the video encoder 200 and the video decoder 300 may use both transform and quantization, rather than skipping the transform process (e.g., in TS coding). In some examples, BDPCM in VVC uses only transform skip (TS) residual coding, but the techniques of this disclosure may be used with other non-TS residual coding methods.

[0135] In a fourth example of the present disclosure, any combination of the example techniques described above can be used for lossless coding. In one example, lossless coding bypasses both transform and quantization. In one example, BDPCM can be used with a transform quantization bypass (TQB) mode flag (e.g., bypassing both transform and quantization) (as in HEVC), so that the intra prediction derivation, context derivation, and alternative residual coding methods described above can be used for lossless coding when using TQB mode.

[0136] In another example, high-level markers (e.g., SPS, PPS, slices) or low-level flags (such as at the transform unit (TU) level or coding unit (CU) level) can be used in both lossy and lossless coding to transition between TS residual and non-TS residual coding methods. The previous techniques described herein can be used with this type of signaling.

[0137] The following are example techniques of the present disclosure. The techniques below can be used together in any combination.

[0138] The video encoder 200 and the video decoder 300 may be configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of video data, determine an intra-prediction mode based on the BDPCM mode for the block of video data, and decode the block of video data according to the BDPCM mode and the intra-prediction mode.

[0139] In one example, the BDPCM mode is a horizontal BDPCM mode, and to determine the intra prediction mode, the video encoder 200 and the video decoder 300 are configured to determine that the intra prediction mode is a horizontal intra prediction mode.

[0140] In another example, the BDPCM mode is a vertical BDPCM mode, and in order to determine the intra prediction mode, the video encoder 200 and the video decoder 300 are configured to determine that the intra prediction mode is a vertical intra prediction mode.

[0141] In another example, in order to determine the intra prediction mode, the video encoder 200 and the video decoder 300 are configured to determine whether the intra prediction mode is one of the planar mode or the DC mode.

[0142] In another example, the video encoder 200 and the video decoder 300 are configured to determine a most probable mode list for the second block of video data based on the determined intra prediction mode.

[0143] In another example, the video encoder 200 and the video decoder 300 are configured to determine a context for a block-based delta pulse coding modulation (BDPCM) mode index based on color components of a block of video data, and entropy code the BDPCM mode index based on the determined context.

[0144] In another example, the video encoder 200 and the video decoder 300 are configured to code blocks of video data using transform skip residual coding.

[0145] In another example, the video encoder 200 and the video decoder 300 are configured to code blocks of video data using conventional residual coding.

[0146] In another example, the video encoder 200 and the video decoder 300 are configured to use a lossless coding mode to code the block of video data. In one example, the lossless coding mode is a transform quantization bypass mode.

[0147] In another example, the video encoder 200 and the video decoder 300 are configured to decode a flag indicating whether transform skip residual coding or normal residual coding is used in one or more of a sequence parameter set, a picture parameter set, a slice header, a coding unit, or a transform unit, and decode a block of video data according to the flag.

[0148] Figure 5 2 is a flowchart illustrating an example method for encoding a current block. The current block may include a current CU. Although described with respect to video encoder 200 ( Figure 1 and Figure 3 ), but it should be understood that other devices may be configured to perform the same Figure 5 A similar approach to the one in the previous section.

[0149] In this example, the video encoder 200 initially 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 and the prediction block for the current block. The video encoder 200 may then transform the residual block and quantize the transform coefficients of the residual block (354). Next, the video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or following the scan, the video encoder 200 may entropy encode the transform coefficients (358). For example, the video encoder 200 may encode the transform coefficients using CAVLC or CABAC. The video encoder 200 may then output the entropy encoded data for the block (360).

[0150] Figure 6 3 is a flow chart illustrating an example method for decoding a current block of video data. The current block may include a current CU. Although described with respect to video decoder 300 ( Figure 1 and Figure 4 ), but it should be understood that other devices may be configured to perform the same Figure 6 A similar approach to the one in the previous section.

[0151] The video decoder 300 may receive entropy-encoded data for a current block, such as entropy-encoded prediction information and entropy-encoded data for coefficients of a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy-encoded data to determine the prediction information for the current block and to reproduce the coefficients of the residual block (372). The video decoder 300 may predict the current block (374), for example, using an intra-prediction mode or an inter-prediction mode 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 coefficients (376) to create a block of quantized transform coefficients. The video decoder 300 may then inverse quantize and inverse transform the transform coefficients to produce a residual block (378). The video decoder 300 may ultimately decode the current block by combining the prediction block and the residual block (380).

[0152] Figure 7 is a flowchart illustrating another example video encoding method. Figure 7 The techniques may be performed by one or more structural components of the video encoder 200 .

[0153] In one example of the present disclosure, the video encoder 200 may be configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of video data (400), determine an intra-prediction mode based on the BDPCM mode for the block of video data (402), and encode the block of video data according to the BDPCM mode and the intra-prediction mode (404).

[0154] In one example, the BDPCM mode is a horizontal BDPCM mode, and to determine the intra-frame prediction mode, the video encoder 200 is configured to determine that the intra-frame prediction mode is a horizontal intra-frame prediction mode. In another example, the BDPCM mode is a vertical BDPCM mode, and to determine the intra-frame prediction mode, the video encoder 200 is configured to determine that the intra-frame prediction mode is a vertical intra-frame prediction mode. In one example, the block of video data is a chroma block of video data. In another example, the block of video data is a luminance block of video data.

[0155] In another example of the present disclosure, the video encoder 200 is configured to determine a context for a syntax element indicating a BDPCM mode for a block of video data based on a color component of the block of video data, and to entropy encode the syntax element indicating the BDPCM mode based on the determined context. In one example, the context is different for different color components.

[0156] In one example of the present disclosure, the video encoder 200 is configured to encode a block of video data using transform skip residual coding. In another example, the video encoder 200 is configured to encode a block of video data using conventional residual coding. In another example, the video encoder 200 is configured to encode a block of video data using lossless coding.

[0157] In another example of the present disclosure, the intra-frame prediction mode is a first intra-frame prediction mode, and the video encoder 200 is configured to determine a most probable mode list for a second block of video data based on the first intra-frame prediction mode, and determine a second intra-frame prediction mode for the second block of video data from the most probable mode list.

[0158] Figure 8 is a flowchart illustrating another example video decoding method. Figure 8 The techniques may be performed by one or more structural components of the video decoder 300 .

[0159] In one example of the present disclosure, the video decoder 300 may be configured to determine a block-based delta pulse coding modulation (BDPCM) mode for a block of video data (450), determine an intra-prediction mode based on the BDPCM mode for the block of video data (452), and decode the block of video data according to the BDPCM mode and the intra-prediction mode (454).

[0160] In one example, the BDPCM mode is a horizontal BDPCM mode, and to determine the intra-prediction mode, the video decoder 300 is configured to determine that the intra-prediction mode is a horizontal intra-prediction mode. In another example, the BDPCM mode is a vertical BDPCM mode, and to determine the intra-prediction mode, the video decoder 300 is configured to determine that the intra-prediction mode is a vertical intra-prediction mode. In one example, the block of video data is a chroma block of video data. In another example, the block of video data is a luminance block of video data.

[0161] In another example of the present disclosure, the video decoder 300 is configured to determine a context for a syntax element indicating a BDPCM mode for a block of video data based on a color component of the block of video data, and entropy decode the syntax element indicating the BDPCM mode based on the determined context. In one example, the context is different for different color components.

[0162] In one example of the present disclosure, the video decoder 300 is configured to decode a block of video data using transform skip residual coding. In another example, the video decoder 300 is configured to decode a block of video data using conventional residual coding. In another example, the video decoder 300 is configured to decode a block of video data using lossless coding.

[0163] In another example of the present disclosure, the intra-frame prediction mode is a first intra-frame prediction mode, and the video decoder 300 is configured to determine a most probable mode list for the second block of video data based on the first intra-frame prediction mode, and determine a second intra-frame prediction mode for the second block of video data from the most probable mode list.

[0164] Item 1 - A method of decoding video data, the method comprising: determining a block-based delta pulse coding modulation (BDPCM) mode for a block of the video data; determining an intra-frame prediction mode based on the BDPCM mode for the block of the video data; and decoding the block of the video data according to the BDPCM mode and the intra-frame prediction mode.

[0165] Clause 2—The method of Clause 1, wherein the BDPCM mode is a horizontal BDPCM mode, and wherein determining the intra prediction mode comprises determining the intra prediction mode is a horizontal intra prediction mode.

[0166] Clause 3 - The method of Clause 1, wherein the BDPCM mode is a vertical BDPCM mode, and wherein determining the intra prediction mode comprises determining the intra prediction mode is a vertical intra prediction mode.

[0167] Clause 4—The method of Clause 1, wherein determining the intra-prediction mode comprises determining that the intra-prediction mode is one of planar mode or DC mode.

[0168] Clause 5 - The method of Clause 1, further comprising determining a most probable mode list for a second block of video data based on the determined intra-prediction mode.

[0169] Clause 6 - A method of coding video data, the method comprising: determining a context for a block-based delta pulse coding modulation (BDPCM) mode index based on color components of a block of the video data; and entropy coding the BDPCM mode index based on the determined context.

[0170] Clause 7 - A method according to any combination of clauses 1 to 6.

[0171] Clause 8 - The method of any combination of clauses 1 - 7, further comprising: coding the block of video data using transform skip residual coding.

[0172] Clause 9 - The method of any combination of clauses 1 - 7, further comprising: decoding the block of video data using conventional residual coding.

[0173] Clause 10 - The method of any combination of clauses 1 - 7, further comprising: decoding the block of video data using a lossless decoding mode.

[0174] Clause 11 - The method of clause 10, wherein the lossless coding mode is a transform quantization bypass mode.

[0175] Clause 12 - A method according to any combination of clauses 1 to 11, further comprising: decoding a flag indicating whether transform skip residual decoding or conventional residual decoding is used in one or more of a sequence parameter set, a picture parameter set, a slice header, a decoding unit, or a transform unit; and decoding a block of video data according to the flag.

[0176] Clause 13 - The method of clauses 1 - 12, wherein decoding comprises decoding.

[0177] Clause 14 - The method of clauses 1 - 13, wherein decoding comprises encoding.

[0178] Clause 15 - An apparatus for decoding video data, the apparatus comprising one or more means for performing the method of any of clauses 1 - 14.

[0179] Clause 16 - The apparatus of clause 15, wherein the one or more units comprise one or more processors implemented in circuitry.

[0180] Clause 17 - The apparatus of any of clauses 15 and 16, further comprising a memory to store video data.

[0181] Clause 18 - The apparatus of any of Clauses 15 - 17, further comprising a display configured to display the decoded video data.

[0182] Clause 19 - A device as described in any of Clauses 15 - 18, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0183] Clause 20 - The apparatus of any of Clauses 15 - 19, wherein the apparatus comprises a video decoder.

[0184] Clause 21 - An apparatus as described in any of Clauses 15 - Clause 20, wherein the apparatus comprises a video encoder.

[0185] Clause 22 - 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 1 - 14.

[0186] It is to be appreciated that, depending on the example, certain acts or events of any of the techniques described herein may be performed in a different sequence, may be added together, combined, or omitted (e.g., not all described acts or events are necessary for practicing the techniques). Furthermore, in some examples, actions or events may be performed simultaneously, for example, through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

[0187] 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 in or sent via a computer-readable medium as one or more instructions or codes, and executed by a hardware-based processing unit. A computer-readable medium can include a computer-readable storage medium corresponding to a tangible medium (such as a data storage medium), or a communication medium including, for example, any medium that facilitates the transmission of a computer program from one place to another according to a communication protocol. In the manner described, a computer-readable medium can generally correspond to (1) a non-transitory tangible computer-readable storage medium or (2) a communication medium such as a signal or carrier wave. A data storage medium can be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the techniques described in the present disclosure. A computer program product can include a computer-readable medium.

[0188] 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 or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. In addition, 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 technology (such as infrared, radio, and microwave), then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology (such as infrared, radio, and microwave) is included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other temporary media, but rather are directed to non-temporary, tangible storage media. As used herein, disks and optical disks 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 typically reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0189] Instructions can 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 logic circuits or discrete logic circuits. Therefore, the terms "processor" and "processing circuitry" as used herein may refer to any of the aforementioned structures or any other structure suitable for the implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware modules and / or software modules configured for encoding and decoding, or incorporated into a combined video codec. In addition, the techniques may be fully implemented in one or more circuits or logic elements.

[0190] The techniques of this disclosure may be implemented in a variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs), or collections of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require implementation by different hardware units. Rather, as described above, the various units may be combined in a video codec hardware unit, or provided by a collection of interoperable hardware units (including one or more processors as described above) in conjunction with appropriate software and / or firmware.

[0191] 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: determining a first block-based delta pulse coding modulation (BDPCM) mode for a luma block of the video data; determining a first intra prediction mode based on the first BDPCM mode for a luma block of the video data; determining a second BDPCM mode for a chroma block of video data; determining a second intra prediction mode based on the second BDPCM mode for a chroma block of the video data; decoding a luma block of the video data according to the first BDPCM mode and the first intra prediction mode; as well as A chroma block of the video data is decoded according to the second BDPCM mode and the second intra prediction mode.

2. The method according to claim 1, wherein The first BDPCM mode is a horizontal BDPCM mode, and wherein determining the first intra prediction mode comprises: It is determined that the first intra prediction mode is a horizontal intra prediction mode.

3. The method according to claim 1, wherein The first BDPCM mode is a vertical BDPCM mode, and wherein determining the first intra prediction mode comprises: It is determined that the first intra prediction mode is a vertical intra prediction mode.

4. The method according to claim 1, further comprising: determining, based on a color component of a luma block of the video data, a first context for a first syntax element indicating the first BDPCM mode for a luma block of the video data; entropy decoding the first syntax element indicating the first BDPCM mode based on the first context; determining, based on color components of chroma blocks of the video data, a second context for a second syntax element indicating the second BDPCM mode for chroma blocks of the video data; as well as The second syntax element indicating the second BDPCM mode is entropy decoded based on the second context.

5. The method according to claim 4, wherein The first context is different from the second context.

6. The method according to claim 1, further comprising: A luma block of the video data is decoded using transform skip residual decoding.

7. The method according to claim 1, further comprising: Luma blocks of the video data are decoded using conventional residual decoding.

8. The method according to claim 1, further comprising: Luma blocks of the video data are decoded using lossless decoding.

9. The method according to claim 1, wherein The luminance block of the video data is a first luminance block of the video data, and the method further includes: determining a most probable mode list for a second luma block of video data based on the first intra prediction mode; and A third intra-prediction mode is determined from the most probable mode list for a second luma block of the video data.

10. The method according to claim 1, further comprising: A picture including the decoded luma blocks of video data and the decoded chroma blocks of video data is displayed.

11. An apparatus configured to decode video data, the apparatus comprising: a memory configured to store luma blocks of video data and chroma blocks of video data; as well as One or more processors in communication with the memory, the one or more processors being configured to: determining a first block-based delta pulse coding modulation (BDPCM) mode for a luma block of the video data; determining a first intra prediction mode based on the first BDPCM mode for a luma block of the video data; determining a second BDPCM mode for a chroma block of the video data; determining a second intra prediction mode based on the second BDPCM mode for a chroma block of the video data; decoding a luma block of the video data according to the first BDPCM mode and the first intra prediction mode; as well as A chroma block of the video data is decoded according to the second BDPCM mode and the second intra prediction mode.

12. The device according to claim 11, wherein The first BDPCM mode is a horizontal BDPCM mode, and wherein, to determine the first intra prediction mode, the one or more processors are further configured to: It is determined that the first intra prediction mode is a horizontal intra prediction mode.

13. The device according to claim 11, wherein The first BDPCM mode is a vertical BDPCM mode, and wherein, to determine the first intra prediction mode, the one or more processors are further configured to: It is determined that the first intra prediction mode is a vertical intra prediction mode.

14. The device according to claim 11, wherein The one or more processors are further configured to: determining, based on a color component of a luma block of the video data, a first context for a first syntax element indicating the first BDPCM mode for a luma block of the video data; entropy decoding the first syntax element indicating the first BDPCM mode based on the first context; determining, based on color components of chroma blocks of the video data, a second context for a second syntax element indicating the second BDPCM mode for chroma blocks of the video data; as well as The second syntax element indicating the second BDPCM mode is entropy decoded based on the second context.

15. The device according to claim 14, wherein The first context is different from the second context.

16. The device according to claim 11, wherein The one or more processors are further configured to: A luma block of the video data is decoded using transform skip residual decoding.

17. The device according to claim 11, wherein The one or more processors are further configured to: Luma blocks of the video data are decoded using conventional residual decoding.

18. The device according to claim 11, wherein The one or more processors are further configured to: Luma blocks of the video data are decoded using lossless decoding.

19. The device according to claim 11, wherein The luma block of video data is a first luma block of video data, and wherein the one or more processors are further configured to: determining a most probable mode list for a second luma block of video data based on the first intra prediction mode; and A third intra-prediction mode is determined from the most probable mode list for a second luma block of the video data.

20. The apparatus according to claim 11, further comprising: A display is configured to display a picture including luminance blocks of decoded video data and chrominance blocks of decoded video data.

21. An apparatus configured to decode video data, the apparatus comprising: means for determining a first block-based delta pulse coding modulation (BDPCM) mode for a luma block of video data; means for determining a first intra prediction mode based on the first BDPCM mode for a luma block of the video data; means for determining a second BDPCM mode for chroma blocks of video data; means for determining a second intra prediction mode based on the second BDPCM mode for a chroma block of the video data; means for decoding a luma block of the video data according to the first BDPCM mode and the first intra prediction mode; as well as Means for decoding chroma blocks of the video data according to the second BDPCM mode and the second intra prediction mode.

22. A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to decode video data to: determining a first block-based delta pulse coding modulation (BDPCM) mode for a luma block of the video data; determining a first intra prediction mode based on the first BDPCM mode for a luma block of the video data; determining a second BDPCM mode for a chroma block of video data; determining a second intra prediction mode based on the second BDPCM mode for a chroma block of the video data; decoding a luma block of the video data according to the first BDPCM mode and the first intra prediction mode; as well as A chroma block of the video data is decoded according to the second BDPCM mode and the second intra prediction mode.

23. An apparatus configured to encode video data, the apparatus comprising: a memory configured to store luma blocks of video data and chroma blocks of video data; as well as One or more processors in communication with the memory, the one or more processors being configured to: determining a first block-based delta pulse coding modulation (BDPCM) mode for a luma block of the video data; determining a first intra prediction mode based on the first BDPCM mode for a luma block of the video data; determining a second BDPCM mode for a chroma block of video data; determining a second intra prediction mode based on the second BDPCM mode for a chroma block of the video data; encoding a luma block of the video data according to the first BDPCM mode and the first intra prediction mode; as well as The chroma blocks of the video data are encoded according to the second BDPCM mode and the second intra prediction mode.

24. The device according to claim 23, wherein The first BDPCM mode is a horizontal BDPCM mode, and wherein, to determine the first intra prediction mode, the one or more processors are further configured to: It is determined that the first intra prediction mode is a horizontal intra prediction mode.

25. The apparatus according to claim 23, wherein The first BDPCM mode is a vertical BDPCM mode, and wherein, to determine the first intra prediction mode, the one or more processors are further configured to: It is determined that the first intra prediction mode is a vertical intra prediction mode.

26. The apparatus according to claim 23, wherein The one or more processors are further configured to: determining, based on a color component of a luma block of the video data, a first context for a first syntax element indicating the first BDPCM mode for a luma block of the video data; entropy encoding the first syntax element indicating the first BDPCM mode based on the first context; determining, based on color components of chroma blocks of the video data, a second context for a second syntax element indicating the second BDPCM mode for chroma blocks of the video data; as well as The second syntax element indicating the second BDPCM mode is entropy encoded based on the second context.

27. The device according to claim 26, wherein The first context is different from the second context.

28. The apparatus according to claim 23, wherein The one or more processors are further configured to: A luma block of the video data is encoded using transform skip residual coding.

29. The apparatus according to claim 23, wherein The one or more processors are further configured to: The luminance blocks of the video data are encoded using conventional residual coding.

30. The apparatus of claim 23, wherein: The one or more processors are further configured to: The luminance blocks of the video data are encoded using lossless coding.

31. The apparatus according to claim 23, wherein The luma block of video data is a first luma block of video data, and wherein the one or more processors are further configured to: determining a most probable mode list for a second luma block of video data based on the first intra prediction mode; and A third intra-prediction mode is determined from the most probable mode list for a second luma block of the video data.

32. The apparatus of claim 23, further comprising: A camera is configured to capture a picture comprising luma blocks of the video data and chroma blocks of the video data.

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