Picture Orientation and Quality Metrics Supplemental Enhancement Information Message for Video Coding

Abstract

Video encoders and video decoders are configured for supplemental enhancement information (SEI) messages. The SEI messages may include a picture orientation transformation type syntax element that indicates how a picture may be rotated and / or mirrored. The SEI messages may also include quality metrics.

Description

[Technical field]

[0001]

[0001] This application claims priority to U.S. Patent Application No. 17 / 653,947, filed March 8, 2022, and U.S. Provisional Application No. 63 / 170,267, filed April 2, 2021, and U.S. Provisional Application No. 63 / 214,378, filed June 24, 2021, the entire contents of each of which are incorporated by reference herein. U.S. Patent Application No. 17 / 653,947, filed March 8, 2022, claims the benefit of U.S. Provisional Application No. 63 / 170,267, filed April 2, 2021, and U.S. Provisional Application No. 63 / 214,378, filed June 24, 2021.

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

[0003] Digital video capabilities may be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones, so-called "smartphones," video teleconferencing devices, video streaming devices, etc. Digital video devices implement video coding techniques such as those described in 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), ITU-T H.266 / Generic Video Coding (VVC), and extensions to such standards, as well as proprietary video codecs / formats such as AOMedia Video1 (AV1) developed by the Alliance for Open Media. By implementing such video coding techniques, video devices may more efficiently transmit, receive, encode, decode, and / or store digital video information.

[0004]

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

[0005]

[0005] In general, this disclosure describes techniques for coding video data. In particular, this disclosure describes techniques for encoding and decoding messages (e.g., supplemental enhancement information (SEI) messages and / or other packetization structures) that include metadata that aids in processing (e.g., decoding, displaying, etc.) of the video data. The messages of this disclosure may include syntax elements that indicate picture orientation and / or transforms applied to the decoded picture that may be used to rotate and / or mirror the decoded picture to a desired orientation. The syntax elements may indicate transformations for display of the entire picture or component pictures (e.g., left-eye and right-eye stereoscopic pictures, etc.). In another example, the messages may include syntax elements that indicate picture quality metrics. The picture quality metrics may indicate the coding quality of the picture, such as quality-based viewpoint switching and quality-based metric measurements.

[0006]

[0006] A video decoder or other device may decode the message and process the picture of the video data according to the message. The picture orientation message may be used to provide the video decoder with instructions on a recommended orientation transformation to be applied to the decoded picture. This may allow a display of the decoded picture to be shown in a more appropriate orientation. The video decoder may use the quality metrics for post-processing of the decoded picture and / or may use the quality metrics to select a higher quality picture to be used for inter prediction.

[0007]

[0007] In one example, the present disclosure describes a method for processing video data comprising receiving a picture and coding a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0008]

[0008] In another example, the present disclosure describes an apparatus configured to process video data, comprising a memory configured to store a picture and one or more processors implemented in a circuit and in communication with the memory, the one or more processors configured to receive a picture and code a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0009]

[0009] In another example, the present disclosure describes an apparatus configured to process video data, comprising: means for receiving a picture; and means for coding a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0010]

[0010] 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 configured to process video data to receive a picture and code a picture orientation message that includes a transform type syntax element, where the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0011]

[0011] In another example, the present disclosure describes a method for processing video data comprising receiving a picture and coding a quality metrics message including a quality metric syntax element, where the quality metric syntax element indicates a value of a quality metric related to the picture.

[0012]

[0012] In another example, the present disclosure describes an apparatus configured to process video data, comprising: a memory configured to store pictures; and one or more processors implemented in a circuit and in communication with the memory, the one or more processors configured to receive a picture; and code a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture.

[0013]

[0013] In another example, the present disclosure describes an apparatus configured to process video data, the apparatus comprising: means for receiving a picture; and means for coding a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture.

[0014]

[0014] 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 configured to process video data to receive a picture and code a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture.

[0015]

[0015] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. [Brief description of the drawings]

[0016] [Figure 1]

[0016] FIG. 1 is a block diagram illustrating an example video encoding and decoding system in which the techniques of this disclosure may be implemented. [Diagram 2]

[0017] 1 is a conceptual diagram illustrating an example rotation of a picture. [Diagram 3]

[0018] 1 is a conceptual diagram illustrating example conversion types. [Figure 4]

[0019] 11 is a flowchart illustrating an example process for coding a picture orientation supplemental enhancement information message. [Diagram 5]

[0020] 11 is a flowchart illustrating an example process for coding a quality metrics supplemental enhancement information message. [Figure 6]

[0021] 1 is a block diagram illustrating an example video encoder that may implement the techniques of this disclosure. [Figure 7]

[0022] 1 is a block diagram illustrating an example video decoder that may implement the techniques of this disclosure. [Figure 8]

[0023] 1 is a flowchart illustrating an example method for encoding a current block in accordance with techniques of this disclosure. [Figure 9]

[0024] 6 is a flowchart illustrating an example method for decoding a current block in accordance with techniques of this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017]

[0025] This disclosure describes techniques for encoding and decoding messages (e.g., Supplemental Enhancement Information (SEI) messages and / or other packetization structures) that include metadata to aid in processing (e.g., decoding, displaying, etc.) video data. The messages of this disclosure may include syntax elements that indicate picture orientation and / or transformations applied to a decoded picture that may be used to rotate and / or mirror the decoded picture to a desired orientation. The syntax elements may indicate transformations for display of the entire picture or component pictures (e.g., left-eye and right-eye stereoscopic pictures, etc.). In another example, the messages may include syntax elements that indicate picture quality metrics. The picture quality metrics may indicate the coding quality of the picture, such as quality-based viewpoint switching and quality-based metric measurements.

[0018]

[0026] A video decoder or other device may decode the message and process pictures of the video data according to the message. The picture orientation message may be used to provide instructions to the video decoder about a recommended orientation transformation to be applied to the decoded picture, so that a display of the decoded picture may be shown in a more appropriate orientation. The video decoder may use the quality metric for post-processing of the decoded picture and / or may use the quality metric to select a higher quality picture to be used for inter prediction.

[0019]

[0027] 1 is a block diagram illustrating an example video encoding and decoding system 100 that may implement techniques of this disclosure. The techniques of this disclosure are generally directed to coding (encoding and / or decoding) video data. In general, video data includes any data for processing video. Thus, video data may include raw uncoded video, coded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.

[0020]

[0028] 1, system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116, in this example. In particular, source device 102 provides the video data to destination device 116 via a computer-readable medium 110. Source device 102 and destination device 116 may comprise any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, mobile devices, tablet computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming devices, broadcast receiver devices, and the like. In some cases, source device 102 and destination device 116 may be equipped for wireless communication and thus may be referred to as wireless communication devices.

[0021]

[0029] In the example of FIG. 1, source device 102 includes a video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes an input interface 122, a video decoder 300, memory 120, and a display device 118. According to this disclosure, the video encoder 200 of source device 102 and the video decoder 300 of destination device 116 may be configured to apply techniques for SEI message coding. Thus, source device 102 represents an example of a video encoding device, and destination device 116 represents an example of a video decoding device. In other examples, the source device and destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source, such as an external camera. Similarly, destination device 116 may interface with an external display device rather than including an integrated display device.

[0022]

[0030] The system 100 shown in FIG. 1 is only an example. In general, any digital video encoding and / or decoding device may implement the techniques for SEI message coding. The source device 102 and the destination device 116 are only examples of coding devices, such that the source device 102 generates coded video data for transmission to the destination device 116. This disclosure refers to a "coding" device as a device that performs coding (encoding and / or decoding) of data. Thus, the video encoder 200 and the video decoder 300 represent examples of coding devices, in particular video encoders and video decoders, respectively. In some examples, the source device 102 and the destination device 116 may operate substantially symmetrically, such that each of the source device 102 and the destination device 116 includes video encoding and video decoding components. Thus, the system 100 may support one-way or two-way video transmission between the source device 102 and the destination device 116, for example, video streaming, video playback, video broadcasting, or video telephony.

[0023]

[0031] Generally, video source 104 represents a source of video data (i.e., raw, unencoded video data) and provides a continuous series of pictures (also called “frames”) of the 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 video camera, a video archive containing previously captured raw video, and / or a video feed interface for receiving video from a video content provider. As a further alternative, video source 104 may generate computer graphics-based data as source video, or a combination of live, archived, and computer-generated video. In each case, video encoder 200 encodes the captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange the pictures from a receiving order (sometimes called a “display order”) to a coding order for coding. Video encoder 200 may generate a bitstream including the encoded video data. The source device 102 may then output the encoded video data onto a computer-readable medium 110 via an output interface 108, for receipt and / or retrieval by, for example, an input interface 122 of a destination device 116.

[0024]

[0032] The memory 106 of the source device 102 and the memory 120 of the destination device 116 represent general-purpose memories. In some examples, the memories 106, 120 may store raw video data, e.g., raw video from the video source 104 and raw decoded video data from the video decoder 300. Additionally or alternatively, the memories 106, 120 may store software instructions executable by, e.g., the video encoder 200 and the video decoder 300, respectively. Although the memories 106 and 120 are shown in this example as separate from the video encoder 200 and the video decoder 300, it should be understood that the video encoder 200 and the video decoder 300 may also include internal memories for functionally similar or equivalent purposes. Additionally, the memories 106, 120 may store encoded video data, e.g., the output from the video encoder 200 and the input to the video decoder 300. In some examples, portions of the memory 106, 120 may be allocated as one or more video buffers, for example, to store raw decoded and / or encoded video data.

[0025]

[0033] The computer-readable medium 110 may represent any type of medium or device capable of transporting encoded video data from the source device 102 to the destination device 116. In one example, the computer-readable medium 110 represents a communication medium for enabling the source device 102 to transmit the encoded video data directly to the destination device 116 in real time, for example, via a radio frequency network or a computer-based network. The output interface 108 may modulate a transmission signal including the encoded video data, and the input interface 122 may demodulate a received transmission signal according to a communication standard such as a wireless communication protocol. The communication medium may comprise any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network, such as a local area network, a wide area network, or a global network such as the Internet. The communication medium may include routers, switches, base stations, or any other equipment that may be useful in facilitating communication from the source device 102 to the destination device 116.

[0026]

[0034] In some examples, source device 102 may output the encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access the encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data.

[0027]

[0035] In some examples, source device 102 may output the encoded video data to a file server 114 or another intermediate storage device, which may store the encoded video data generated by source device 102. Destination device 116 may access the stored video data from file server 114 via streaming or download.

[0028]

[0036] 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 destination device 116. The file server 114 may represent a web server (e.g., for a website), a server configured to provide a file transfer protocol service (such as File Transfer Protocol (FTP) or File Delivery over Unidirectional Transport (FLUTE) protocol), a content delivery network (CDN) device, a Hypertext Transfer Protocol (HTTP) server, a Multimedia Broadcast Multicast Service (MBMS) or enhanced MBMS (eMBMS) server, and / or a network attached storage (NAS) device. 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.

[0029]

[0037] The destination device 116 may access the encoded video data from the file server 114 through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., a Digital Subscriber Line (DSL), a cable modem, etc.), or a combination of both, that is suitable for accessing the encoded video data stored on the file server 114. The input interface 122 may be configured to operate according to any one or more of the various protocols described above for retrieving or receiving media data from the file server 114, or other such protocols for retrieving media data.

[0030]

[0038] The output interface 108 and the input interface 122 may represent a wireless transmitter / receiver, a modem, a wired networking component (e.g., an Ethernet card), a wireless communication component operating according to any of the various IEEE 802.11 standards, or other physical components. In examples in which the output interface 108 and the input interface 122 comprise wireless components, the output interface 108 and the input interface 122 may be configured to transfer data, such as encoded video data, according to a cellular communication standard, such as 4G, 4G-LTE (Long Term Evolution), LTE Advanced, 5G, etc. In some examples in which the output interface 108 comprises a wireless transmitter, the output interface 108 and the input interface 122 may be configured to transfer data, such as encoded video data, according to other wireless standards, such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., ZigBee), the Bluetooth standard, etc. In some examples, the source device 102 and / or the destination device 116 may include respective system-on-chip (SoC) devices. For example, the source device 102 may include a SoC device for performing functions attributable to the video encoder 200 and / or the output interface 108, and the destination device 116 may include a SoC device for performing functions attributable to the video decoder 300 and / or the input interface 122.

[0031]

[0039] The techniques of this disclosure may be applied to video coding supporting any of a variety of multimedia applications, such as over-the-air television broadcast, cable television transmission, satellite television transmission, Internet streaming video transmission such as Dynamic Adaptive Streaming over HTTP (DASH), digital video encoded on a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

[0032]

[0040] The input interface 122 of the destination device 116 receives the encoded video bitstream from the computer-readable medium 110 (e.g., a communication medium, the storage device 112, the file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200 that is also used by the video decoder 300, such as syntax elements having values ​​that describe characteristics and / or processing of video blocks or other coded units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays decoded pictures of the decoded video data to a user. The display device 118 may represent any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0033]

[0041] Although not shown in FIG. 1, 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 handle multiplexed streams that include both audio and video in a common data stream.

[0034]

[0042] The video encoder 200 and the video decoder 300 may each be implemented as any of a variety of suitable encoder and / or decoder circuits, or any combination thereof, 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, etc. When the techniques are implemented partially in software, the device may store instructions for the software on a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to implement the techniques of this disclosure. Each of the video encoder 200 and the video decoder 300 may be included in one or more encoders or decoders, any of which may 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 comprise an integrated circuit, a microprocessor, and / or a wireless communication device such as a cellular phone.

[0035]

[0043] The video encoder 200 and the video decoder 300 may operate according to a video coding standard, such as ITU-T H.265, also referred to as High Efficiency Video Coding (HEVC), or extensions thereof, such as multiview and / or scalable video coding extensions. Alternatively, the video encoder 200 and the video decoder 300 may operate according to other proprietary or industry standards, such as ITU-T H.266, also referred to as Generic Video Coding (VVC). In other examples, the video encoder 200 and the video decoder 300 may operate according to a proprietary video codec / format, such as AOMedia Video1 (AV1), an extension of AV1, and / or a successor version of AV1 (e.g., AV2). In other examples, the video encoder 200 and the video decoder 300 may operate according to other proprietary formats or industry standards. However, the techniques of this disclosure are not limited to any particular coding standard or format. In general, video encoder 200 and video decoder 300 may be configured to implement the techniques of this disclosure with any video coding technique that uses SEI messages to determine picture orientation and / or picture quality metrics.

[0036]

[0044] Generally, the video encoder 200 and the video decoder 300 may perform block-based coding of pictures. The term “block” generally refers to a structure that includes data to be processed (e.g., encoded, decoded, or otherwise used in an encoding and / or decoding process). For example, a block may include a two-dimensional matrix of samples of luminance and / or chrominance data. Generally, the video encoder 200 and the video decoder 300 may code video data represented in a YUV (e.g., Y, Cb, Cr) format. That is, rather than coding red, green, and blue (RGB) data for a sample of a picture, the video encoder 200 and the video decoder 300 may code a luminance component and a chrominance component, where the chrominance component may include both red and blue hues of chrominance components. In some examples, the video encoder 200 converts received RGB format data to a YUV representation prior to encoding, and the video decoder 300 converts the YUV representation to the RGB format. Alternatively, pre-processing and post-processing units (not shown) may perform these conversions.

[0037]

[0045] This disclosure may generally refer to coding (e.g., encoding and decoding) a picture to include processes of encoding or decoding data for a picture. Similarly, this disclosure may refer to coding a block of a picture to include processes of encoding or decoding data for the block, e.g., predictive and / or residual coding. A coded video bitstream generally includes a series of values ​​for syntax elements that represent coding decisions (e.g., coding modes) and partitioning of a picture into blocks. Thus, references to coding a picture or a block should be understood generally as coding values ​​for the syntax elements that form the picture or block.

[0038]

[0046] HEVC defines various blocks, including coding units (CUs), prediction units (PUs), and transform units (TUs). According to HEVC, a video coder (such as video encoder 200) partitions coding tree units (CTUs) into CUs according to a quadtree structure. That is, the video coder partitions CTUs and CUs into four equal non-overlapping squares, and each node of the quadtree has either zero or four child nodes. A node without children may be called a "leaf node", and a CU of such a leaf node may include one or more PUs and / or one or more TUs. The video coder may further partition PUs and TUs. For example, in HEVC, a residual quadtree (RQT) represents the partition of TUs. In HEVC, a PU represents inter-predicted data, and a TU represents residual data. An intra-predicted CU includes intra-prediction information, such as an intra-mode indication.

[0039]

[0047] As another example, the video encoder 200 and the video decoder 300 may be configured to operate according to VVC. According to VVC, a video coder (such as the video encoder 200) partitions a picture into multiple coding tree units (CTUs). The video encoder 200 may partition the CTUs according to a tree structure, such as a quad-tree binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT structure eliminates the concept of multiple partition types, such as the separation between CUs, PUs, and TUs in HEVC. The QTBT structure includes two levels, a first level partitioned according to a quad-tree partition and a second level partitioned according to a binary tree partition. The root node of the QTBT structure corresponds to a CTU. The leaf nodes of the binary tree correspond to coding units (CUs).

[0040]

[0048] In the MTT partitioning structure, blocks may be partitioned using quad tree (QT) partitioning, binary tree (BT) partitioning, and one or more types of triple tree (TT) (also called ternary tree (TT)) partitioning. A triple tree or ternary tree partitioning is a partitioning in which a block is split into three sub-blocks. In some examples, a triple tree or ternary tree partitioning splits 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) may be symmetric or asymmetric.

[0041]

[0049] When operating according to the AV1 codec, the video encoder 200 and the video decoder 300 may be configured to code the video data on a block-by-block basis. In AV1, the largest coding block that can be processed is called a superblock. In AV1, a superblock can be either 128×128 luma samples or 64×64 luma samples. However, in successor video coding formats (e.g., AV2), a superblock may be defined with a different (e.g., larger) luma sample size. In some examples, a superblock is the top level of a block quad tree. The video encoder 200 may further partition the superblock into smaller coding blocks. The video encoder 200 may partition the superblock and other coding blocks into smaller blocks using square or non-square partitions. The non-square blocks may include N / 2×N, N×N / 2, N / 4×N, and N×N / 4 blocks. The video encoder 200 and the video decoder 300 may perform separate prediction and transformation processes for each of the coding blocks.

[0042]

[0050] AV1 also defines tiles of video data. A tile is a rectangular array of superblocks that may be coded independently of other tiles. That is, video encoder 200 and video decoder 300 may encode and decode coding blocks within a tile, respectively, without using video data from other tiles. However, video encoder 200 and video decoder 300 may perform filtering across tile boundaries. Tiles may be of uniform or non-uniform size. Tile-based coding may enable parallel processing and / or multithreading for encoder and decoder implementation.

[0043]

[0051] In some examples, video encoder 200 and video decoder 300 may use a single QTBT or MTT structure to represent each of the luminance and chrominance components, and in other examples, video encoder 200 and video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT / MTT structure for the luminance component and another QTBT / MTT structure for both chrominance components (or two QTBT / MTT structures for each chrominance component).

[0044]

[0052] Video encoder 200 and video decoder 300 may be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, superblock partitioning, or other partitioning structures.

[0045]

[0053] In some examples, the CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples for a picture with three sample arrays, or a CTB of samples for a monochrome picture, or a picture coded using three separate color planes and syntax structures used to code the samples. The CTB may be an N×N block of samples for some value of N such that the division of the components into the CTB is partitioned. The components are arrays or single samples from one of the three arrays (luma and two chromas) that configure the picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or single sample of an array that configures the picture in monochrome format. In some examples, the coding block is an M×N block of samples for some value of M and N such that the division of the CTB into coding blocks is partitioned.

[0046]

[0054] Blocks (e.g., CTUs or CUs) may be grouped in various ways in a picture. As an example, a brick may refer to a rectangular region of a CTU row in a particular tile in a picture. A tile may be a rectangular region of a CTU in a particular tile column and a particular tile row in a picture. A tile column refers to a rectangular region of a CTU having a height equal to the height of the picture and a width specified by a syntax element (e.g., in a picture parameter set). A tile row refers to a rectangular region of a CTU having a height specified by a syntax element (e.g., in a picture parameter set) and a width equal to the width of the picture.

[0047]

[0055] In some examples, a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that is not partitioned 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. Bricks in a picture may also be arranged in slices. A slice may be an integer number of bricks of a picture that may be contained entirely in a single Network Abstraction Layer (NAL) Unit. In some examples, a slice includes either several complete tiles or only a continuous sequence of complete bricks of one tile.

[0048]

[0056] This disclosure may use "NxN" and "N by N", e.g., 16x16 samples or 16 by 16 samples, interchangeably to refer to sample dimensions of a block (such as a CU or other video block) in terms of vertical and horizontal dimensions. Generally, a 16x16 CU has 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Similarly, an NxN CU generally has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. Samples in a CU may be arranged in rows and columns. Moreover, a CU does not necessarily have to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may comprise NxM samples, where M is not necessarily equal to N.

[0049]

[0057] The video encoder 200 encodes video data for a CU that represents prediction and / or residual information, as well as other information. The prediction information indicates how the CU should be predicted to form a predictive block for the CU. The residual information generally represents sample-by-sample differences between samples of the CU prior to encoding and the predictive block.

[0050]

[0058] To predict a CU, the video encoder 200 may generally form a predictive block for the CU through inter-prediction or intra-prediction. Inter-prediction generally refers to predicting a CU from data of a previously coded picture, while intra-prediction generally refers to predicting a CU from previously coded data of the same picture. To perform inter-prediction, the video encoder 200 may generate a predictive block using one or more motion vectors. The video encoder 200 may generally perform a motion search to identify a reference block that closely matches the CU, for example, with respect to the difference between the CU and the reference block. The video encoder 200 may calculate a difference metric using a sum of absolute differences (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared difference (MSD), or other such difference calculation to determine whether the reference block closely matches the current CU. In some examples, the video encoder 200 may predict the current CU using unidirectional or bidirectional prediction.

[0051]

[0059] Some examples of VVC also provide an affine motion compensation mode, which may be considered an inter-prediction mode. In an affine motion compensation mode, video encoder 200 may determine two or more motion vectors that represent non-translational motion, such as zooming in or out, rotation, perspective motion, or other irregular motion types.

[0052]

[0060] To perform intra prediction, the video encoder 200 may select an intra prediction mode to generate a predictive block. Some examples of VVC provide 67 intra prediction modes, including various directional modes, as well as planar and DC modes. In general, the video encoder 200 selects an intra prediction mode that describes neighboring samples relative to a current block (e.g., a block of a CU) from which samples of the current block should be predicted. Such samples may generally be above, to the left of, or to the left of the current block in the same picture as the current block, assuming that the video encoder 200 codes the CTUs and CUs in raster scan order (left to right, top to bottom).

[0053]

[0061] Video encoder 200 encodes data representing a prediction mode for the current block. For example, in an inter prediction mode, video encoder 200 may encode data representing which of various available inter prediction modes is used, as well as motion information for the corresponding mode. For example, in unidirectional or bidirectional inter prediction, video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. Video encoder 200 may use similar modes to encode motion vectors for affine motion compensation modes.

[0054]

[0062] AV1 includes two general techniques for encoding and decoding coding blocks of video data. The two general techniques are intra prediction (e.g., intra-frame prediction or spatial prediction) and inter prediction (e.g., inter-frame prediction or temporal prediction). In the context of AV1, when predicting a block of a current frame of video data using an intra prediction mode, the video encoder 200 and the video decoder 300 do not use video data from other frames of the video data. In most intra prediction modes, the video encoder 200 encodes a block of the current frame based on the difference between a sample value in the current block and a predicted value generated from a reference sample in the same frame. The video encoder 200 determines the predicted value generated from the reference sample based on the intra prediction mode.

[0055]

[0063] Following prediction, such as intra- or inter-prediction, of a block, the video encoder 200 may calculate residual data for the block. The residual data, such as a residual block, represents sample-by-sample differences between the block and a predictive block for the block formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to produce transformed data in a transform domain rather than the sample domain. For example, the video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Additionally, the video encoder 200 may apply a secondary transform, such as a mode-dependent non-separable secondary transform (MDNSST), a signal-dependent transform, a Karhunen-Loeve transform (KLT), etc., following the first transform. The video encoder 200 produces transform coefficients following application of the one or more transforms.

[0056]

[0064] As mentioned above, following any transformation to produce transform coefficients, the video encoder 200 may perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to possibly reduce the amount of data used to represent the transform coefficients, providing further compression. By performing a quantization process, the video encoder 200 may reduce the bit depth associated with some or all of the transform coefficients. For example, the video encoder 200 may round an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 may perform a bitwise right shift of the value to be quantized.

[0057]

[0065] Following quantization, the video encoder 200 may scan the transform coefficients to produce a one-dimensional vector from a two-dimensional matrix including the quantized transform coefficients. The scan may be designed to place higher energy (and therefore lower frequency) transform coefficients at the front of the vector and lower energy (and therefore higher frequency) transform coefficients at the rear of the vector. In some examples, the video encoder 200 may utilize a predefined scan order to scan the quantized transform coefficients to produce a serialized vector, and then entropy code the quantized transform coefficients of the vector. In other examples, the video encoder 200 may perform an adaptive scan. After scanning the quantized transform coefficients to form the one-dimensional vector, the video encoder 200 may entropy code the one-dimensional vector, for example, according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy code values ​​for syntax elements that describe metadata associated with the encoded video data for use by the video decoder 300 in decoding the video data.

[0058]

[0066] To implement CABAC, the video encoder 200 may assign a context in a context model to a symbol to be transmitted. The context may relate, for example, to whether neighboring values ​​of the symbol are zero-valued or not. The probability determination may be based on the context assigned to the symbol.

[0059]

[0067] Video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, for video decoder 300, e.g., in a picture header, block header, slice header, or other syntax data, such as a sequence parameter set (SPS), a picture parameter set (PPS), or a video parameter set (VPS). Video decoder 300 may similarly decode such syntax data to determine how to decode corresponding video data.

[0060]

[0068] In this manner, video encoder 200 may generate a bitstream including syntax elements that describe encoded video data, e.g., partitions of a picture into blocks (e.g., CUs) and predictive and / or residual information for the blocks. Finally, video decoder 300 may receive the bitstream and decode the encoded video data.

[0061]

[0069] In general, the video decoder 300 performs an inverse process of that performed by the video encoder 200 to decode the encoded video data of the bitstream. For example, the video decoder 300 may decode values ​​for syntax elements of the bitstream using CABAC in a manner that is inverse to, but substantially similar to, the CABAC encoding process of the video encoder 200. The syntax elements may define partition information for partitioning a picture into CTUs and partitions of each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU. The syntax elements may further define prediction and residual information for blocks (e.g., CUs) of video data.

[0062]

[0070] The residual information may be represented, for example, by quantized transform coefficients. The video decoder 300 may dequantize and inverse transform the quantized transform coefficients of the block to reconstruct a residual block for the block. The video decoder 300 uses the signaled prediction mode (intra- or inter-prediction) and associated prediction information (e.g., motion information for inter-prediction) to form a predictive block for the block. The video decoder 300 may then combine (sample-by-sample) the predictive block and the residual block to reconstruct 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]

[0071] This disclosure may generally refer to "signaling" certain information, such as a syntax element. The term "signaling" may generally refer to communication of values ​​for syntax elements and / or other data used to decode encoded video data. That is, video encoder 200 may signal values ​​for syntax elements in a bitstream. Generally, signaling refers to generating values ​​in a bitstream. As mentioned above, source device 102 may transport the bitstream to destination device 116 in substantially real-time or may transport the bitstream to destination device 116 in non-real-time, such as may be done when storing syntax elements in storage device 112 for later retrieval by destination device 116.

[0064]

[0072] In general, this disclosure describes techniques for coding video data. In particular, this disclosure describes techniques for decoding SEI messages. The SEI messages of this disclosure may include a syntax element indicating a picture orientation. In another example, the SEI message may include a syntax element indicating a picture quality metric. A video decoder or other device may decode the SEI message and process pictures of the video data according to the SEI message.

[0065]

[0073] The General Supplemental Enhancement Information (VSEI) standard (e.g., ITU-T H.274 and ISO / IEC 23002-7) specifies several video usability information (VUI) and SEI messages for use with VVC bitstreams. The SEI messages allow the video encoder 200 to include metadata in the bitstream that is not necessary for accurate decoding of the output picture sample values, but can be used for various other purposes. The video encoder 200 may be configured to include any number of SEI network abstraction layer (NAL) units in an access unit, and each SEI NAL unit may include one or more SEI messages. Specifications and systems that use VVC may specify that the encoder generate certain SEI messages or may define specific handling of certain types of received SEI messages.

[0066]

[0074] ISO / IEC JTC 1 / SC 29 / WG 11 N 18277, "Information technology - High efficiency coding and media distribution in heterogeneous environments - Part 2: High efficiency video coding", 2019 ("HEVC") specifies a display orientation SEI message to inform a decoder (e.g., video decoder 300) of the recommended transforms to be applied to cropped decoded pictures before display. The syntax structure of the HEVC display orientation SEI message is shown in Table 1, below.

[0067]

[0075]

[0068] [Table 1]

[0069]

[0076] As can be seen from Table 1, the HEVC display orientation SEI message allows for indication of horizontal flip (hor_flip), vertical flip (ver_flip), and anticlockwise_rotation transforms.

[0070]

[0077] 3GPP specifies Coordinated Video Orientation (CVO) in Technical Specification (TS) 26.114, "IP Multimedia Subsystem (IMS); Multimedia Telephony; Media Handling and Interaction," 2021. CVO signals the current orientation of an image captured at the sender side (e.g., at source device 102) to a receiver (e.g., destination device 116) for appropriate rendering and display. CVO information for less granular rotation is carried as bytes formatted as follows to support horizontal flips and 90 degree rotations: Bit # 7 6 5 4 3 2 1 0 (LSB) Definition 0 0 0 0 CF R1 R0 LSB stands for least significant bit

[0078] The CVO information for higher granularity rotations is carried as bytes formatted as follows: Bit # 7 6 5 4 3 2 1 0 (LSB) Definition R5 R4 R3 R2 CF R1 R0

[0079] Some current examples of the VSEI standard do not support any orientation metadata. The HEVC display orientation SEI message does not consider the case of frame packing, where rotation is to be applied to each component picture rather than the entire picture. FIG. 2 shows an example of display rotation of a frame-packed picture, where each component picture is rotated respectively. As shown in FIG. 2, picture 150 includes two component pictures (e.g., a left-eye picture and a right-eye picture for stereoscopic video). Using the techniques of this disclosure, video encoder 200 may send an SEI message with a code including a transform type syntax element that instructs video decoder 300 to perform a rotation transform on each of the component pictures to obtain transformed picture 152.

[0071]

[0080] The exemplary VSEI region-wise packing (RWP) SEI message provides information to enable remapping of color samples of a cropped decoded picture onto a projected picture, where the RWP SEI message is used when omnidirectional video projection is indicated as being applied to a picture. An RWP SEI message with rwp_cancel_flag equal to 0 should not be present in a coded layered video sequence (CLVS) applied to a picture.

[0072]

[0081] Picture quality metrics are used to evaluate picture quality and coding performance. ISO / IEC 23001-10, "Information technology - MPEG Systems Engineering - Part 10: Carriage of time-specific metadata metrics of media in ISO base media file formats", 2015, specifies the carriage of time-specific metadata metrics of media, such as peak signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), video quality metric (VQM), and mean opinion score (MOS) for ISOBMFF (ISO / IEC base media file format). Rankings related to picture quality are also specified in OMAF, ISO / IEC JTC1 / SC29 / WG11 N19042, "Text of ISO / IEC DIS 23090-2 2nd Edition OMAF", 2020, and Immersive Media Metrics (IMM), which facilitates quality-dependent viewpoint switching and immersive media metrics measurement, ISO / IEC JTC1 / SC29 / WG3 N0073, "ISO / IEC 23090-6 IS for Immersive Media Metrics", 2020. Some picture quality metrics, such as PSNR and SSIM, can only be obtained on the encoder side. SEI messages for carrying such information can provide relevant information to system applications.

[0073]

[0082] Picture Orientation SEI Message

[0083] According to one example of the disclosure, the video encoder 200 is configured to generate and signal a picture orientation SEI message including one or more syntax elements shown in Table 2 below. In particular, the video encoder 200 may be configured to generate and encode a transform type syntax element (e.g., por_transform_type), where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture. The video encoder 200 may also be configured to generate and encode one or more of the other syntax elements and flags listed in Table 2. The video decoder 300 may be configured to receive the picture orientation SEI message and may process and / or display the picture according to the syntax elements included therein. For example, the video decoder 300 may be configured to apply the transform indicated by the transform type syntax element to the decoded picture.

[0074]

[0084]

[0075] [Table 2]

[0076]

[0085] In general, the picture orientation (POR) SEI message provides information to inform the video decoder 300 of a transformation that is recommended to be applied to a decoded picture before display. In some examples, the decoded picture may be a cropped picture.

[0077]

[0086] A value of the syntax element por_cancel_flag equal to 1 indicates that the current SEI message cancels the persistence of any previous POR SEI message in the output order. A value of the syntax element por_cancel_flag equal to 0 indicates that POR information follows.

[0078]

[0087] The value of the syntax element por_persistence_flag specifies the persistence of the POR SEI message in the current layer.

[0079]

[0088] A value of the syntax element por_persistence_flag equal to 0 specifies that the POR SEI message applies only to the current decoded picture.

[0080]

[0089] A value of the syntax element por_persistence_flag equal to 1 specifies that the POR SEI message applies to the currently decoded picture and persists for all subsequent pictures of the current layer in output order until one or more of the following conditions become true:

[0081] A new CLVS for the current tier will begin.

[0082] The bitstream ends.

[0083] The picture of the current layer of the access unit (AU) associated with the POR SEI message that follows the current picture in output order is output.

[0084]

[0090] A value of the syntax element por_constituent_picture_matching_flag equal to 1 specifies that this SEI message applies to each component picture individually and the stereoscopic frame packing format is indicated by the frame packing arrangement SEI message. A value of the syntax element por_constituent_picture_matching_flag equal to 0 specifies that this SEI message applies to the cropped decoded picture.

[0085]

[0091] The value of the syntax element por_constituent_picture_matching_flag shall be equal to 0 if any of the following conditions are true:

[0086] StereoFlag is equal to 0.

[0087] StereoFlag is equal to 1 and fp_arrangement_type is equal to 5.

[0088]

[0092] A value of StereoFlag equal to 0 indicates that there is no frame packing arrangement SEI message with fp_arrangement_cancel_flag equal to 0 that applies to the picture. A value of StereoFlag equal to 1 indicates that the associated picture is a frame packed picture.

[0089]

[0093] A value of the syntax element fp_arrangement_type equal to 5 indicates that the component planes of the output cropped decoded picture in output order form a temporal interleaving of alternating first and second component frames.

[0090]

[0094] The value of the syntax element por_transform_type specifies a transformation (e.g., rotation, mirroring, or a combination of rotation and mirroring) that may be applied to a picture. Note that in some examples, mirroring may also be referred to as flipping. When the transformation indicated by por_transform_type specifies both rotation and mirroring, the video decoder 300 may be configured to apply a rotation transformation before applying the mirroring, or vice versa. Exemplary values ​​of por_transform_type are specified in Table 3 below. In one example, values ​​of por_transform_type from 8 to 31 are reserved for future use by ITU-T|ISO / IEC.

[0091]

[0095]

[0092] [Table 3]

[0093]

[0096] The specific values ​​in Table 3 are only examples. In other examples, more or fewer transform types may be specified, and the transforms may be specified in a different order than shown in Table 3.

[0094]

[0097] FIG. 3 is a conceptual diagram illustrating exemplary transform types. In the example of Table 3, when the transform syntax element has a value of 0, the video decoder 300 may not apply a transform. FIG. 3 shows the original picture 160 with no transform applied. The other transform types in FIG. 3 will be shown with reference to the original picture 160. When the transform syntax element has a value of 1, the video decoder 300 may apply a horizontal mirroring transform to the original picture 160 to obtain picture 162. Horizontal mirroring may also be referred to as horizontal flipping. When the transform syntax element has a value of 2, the video decoder 300 may apply a 180 degree anticlockwise rotation transform to the original picture 160 to obtain picture 164. When the transform syntax element has a value of 3, video decoder 300 may apply a 180 degree counterclockwise rotation transform to original picture 160 , followed by a horizontal mirroring transform to obtain picture 166 .

[0095]

[0098] When the transform syntax element has a value of 4, the video decoder 300 may apply a 90 degree counterclockwise rotation transform to the original picture 160 followed by a horizontal mirroring transform to obtain picture 168. When the transform syntax element has a value of 5, the video decoder 300 may apply a 90 degree counterclockwise rotation transform to the original picture 160 to obtain picture 170. When the transform syntax element has a value of 6, the video decoder 300 may apply a 270 degree counterclockwise rotation transform to the original picture 160 followed by a horizontal mirroring transform to obtain picture 172. When the transform syntax element has a value of 7, the video decoder 300 may apply a 270 degree counterclockwise rotation transform to the original picture 160 to obtain picture 174.

[0096]

[0099] 4 is a flowchart illustrating an example process for coding a picture orientation supplemental enhancement information message. FIG. 4 illustrates both the encoding process and the decoding process of the present disclosure. As shown in FIG. 4, the encoding process may be performed by a source device 102 including a video encoder 200. The decoding process may be performed by a destination device 116 including a video decoder 300.

[0097]

[0100] In one example of the disclosure, the source device 102 may be configured to receive a picture (400). The source device 102 may be further configured to encode the picture (e.g., with the video encoder 200) and transmit the encoded video bitstream to the destination device 116. The source device 102 may be further configured to determine a recommended transform type for the picture (402). The recommended transform type may be a transform type of a plurality of transform types. The source device 102 may be further configured to encode a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture (404).

[0098]

[0101] The destination device 116 may be configured to receive the picture (410). The destination device 116 may be further configured to decode the picture (e.g., with the video decoder 300). The destination device 116 may also decode a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture (412). The destination device 116 may be further configured to apply a transform to the picture in accordance with the transform type syntax element to form a transformed picture (414) and display the transformed picture (416).

[0099]

[0102] In one example of this disclosure, the picture orientation message comprises a picture orientation sSEI message. In another example, the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0100]

[0103] As described above, the plurality of transforms includes two or more of a rotation transform, a mirroring transform, or a combination of a rotation and a mirroring transform. In a more detailed example, the plurality of transforms includes a first transform comprising a horizontal mirroring transform, a second transform comprising a 180 degree counterclockwise rotation transform, a third transform comprising a 180 degree counterclockwise transform followed by a horizontal mirroring transform, a fourth transform comprising a 90 degree anticlockwise transform followed by a horizontal mirroring transform, a fifth transform comprising a 90 degree anticlockwise transform, a sixth transform comprising a 270 degree anticlockwise transform followed by a horizontal mirroring transform, and a seventh transform comprising a 270 degree anticlockwise transform. In yet another example, the transform type syntax element further includes a value indicating that no transform is applied.

[0101]

[0104] In some examples, video encoder 200 may signal fine-grained rotation in an SEI message. Fine-grained rotation and mirroring may be applied to each component picture. In general, fine-grained rotation may indicate relatively small increments of rotation angles. For example, fine-grained rotation may include rotating a picture by an angle less than 90 degrees. In cases where each component picture may have a different rotation, video encoder 200 may specify separate orientation transformation types or fine-grained rotations in the SEI message or other metadata types, each applied to one component picture.

[0102]

[0105] In some examples, the video encoder 200 may specify a component picture match flag in the CVO signaling, which indicates the granularity of the rotation applied to each component picture.

[0103]

[0106] Picture Quality Metrics SEI Message

[0107] According to another example of the disclosure, the video encoder 200 is configured to generate and signal a picture quality metrics message (e.g., an SEI message and / or other packetization structure) that includes one or more of the syntax elements shown in Table 4 below. The video decoder 300 may be configured to receive the picture quality metrics SEI message and process and / or display pictures according to the syntax elements included therein. For example, the destination device 116 and / or the video decoder 300 may be configured to apply one or more post-processing techniques to the decoded pictures according to the quality metrics indicated in the picture quality metrics SEI message. Exemplary post-processing techniques may include upscaling the decoded pictures based on the picture quality. In other examples, the video decoder 300 may be configured to use the quality metrics to select particular pictures for use in inter prediction. For example, when multiple versions of the same picture are available, the video decoder 300 may be configured to select the picture with the highest quality metric (e.g., lowest signal-to-noise ratio) to use as a reference picture in inter prediction.

[0104]

[0108] Table 4 is one example picture quality metrics SEI message: The picture quality metrics SEI message provides quality metrics for each color component of the current decoded picture.

[0105]

[0109]

[0106] [Table 4]

[0107]

[0110] The value of the syntax element pqm_metric_type indicates the type of quality metric associated with the component, as specified in Table 5. Values ​​of pqm_metric_type from 4 to 127 are reserved for future use by ITU-T|ISO / IEC and shall not be present in payload data conforming to this version of this specification.

[0108]

[0111]

[0109] [Table 5]

[0110]

[0112] The quality metric type PSNR is a peak signal-to-noise ratio. The quality metric type SSIM is a structural similarity index. The quality metric MS-SSIM is a multi-scale structural similarity index. The quality metric type VQM is a video quality metric.

[0111]

[0113] A value of the syntax element pqm_single_component_flag equal to 1 specifies that the picture associated with the picture quality metrics SEI message contains a single color component. A value of the syntax element pqm_single_component_flag equal to 0 specifies that the picture associated with the picture quality metrics SEI message contains three color components. The value of pqm_single_component_flag shall be equal to (ChromaFormatIdc==0).

[0112]

[0114] The value of the syntax element pqm_psnr[cIdx] specifies the value of the PSNR. The corresponding PSNR of a color component cIdx of the decoded picture is derived as follows (expressed in floating point):

[0113] PSNR=pqm_psnr[cIdx] / 100; with the exception of PSNR=infinity for pqm_psnr[cIdx] equal to 0.

[0114]

[0115] The value of the syntax element pqm_ssim[cIdx] specifies the value of the SSIM. The corresponding SSIM of a decoded picture color component cIdx is derived as follows (expressed in floating point):

[0115] SSIM=(pqm_ssim[cIdx]-127) / 128

[0116] The value of the syntax element pqm_msssim[cIdx] specifies the value of the MS-SSIM. The corresponding MS-SSIM of the decoded picture color component cIdx is derived as follows (expressed in floating point):

[0116] MS SSIM=(pqm_msssim[cIdx]-127) / 128

[0117] The value of the syntax element pqm_vqm[cIdx] specifies the value of the VQM. The corresponding VQM of the decoded picture color component cIdx is derived as follows (expressed in floating point):

[0117] VQM=pqm_vqm[cIdx] / 50

[0118] The picture quality metrics SEI message may also carry other quality-related metrics, such as Perceptual Assessment of Video Quality (PEVQ), Mean Opinion Score (MOS), and / or other picture quality metrics.

[0118]

[0119] In some examples, the picture quality metrics SEI message may specify quality metrics for each component picture when the picture is associated with a stereoscopic frame packing arrangement SEI message. The picture quality metrics SEI message may specify quality metrics for each region when the picture is associated with a region-by-region frame packing SEI message. Additional syntax elements may be added to the SEI message to indicate whether picture quality metrics are present for each component picture or each region.

[0119]

[0120] In other examples, a picture quality metrics SEI message may carry quality metrics for one or more subpictures or regions-of-interest (ROIs) of the picture associated with the SEI message. Syntax elements indicating the number of subpictures or ROIs, syntax elements indicating the positions of the subpictures or ROIs, and / or syntax elements indicating the sizes of the subpictures or ROIs may also be specified in the SEI message.

[0120]

[0121] Additional quality metrics such as weighted PSNR (wPSNR) and weighted-to-spherically uniform PSNR (WS-PSNR) may also be included in the SEI message to indicate the quality of high dynamic range (HDR) and 360 video content.

[0121]

[0122] Another example picture metrics SEI message format is provided in Table 6.

[0122] [Table 6]

[0123]

[0123] The above picture metrics SEI message provides quality metrics for the current decoded picture.

[0124]

[0124] The value of the syntax element pqm_cnt_minus1 plus 1 specifies the number of luma component quality metrics indicated by the SEI message.

[0125]

[0125] The value of the syntax element pqm_type[i] indicates the i-th quality metric type associated with the decoded picture or video sequence, as specified in Table 7.

[0126] [Table 7]

[0127]

[0126] Quality metric type PSNR sequenc ,wPSNR sequence , and WS-PSNR sequence denote the PSNR, wPSNR, and WS-PSNR of multiple pictures across a sequence, respectively.

[0128]

[0127] The value of the syntax element pqm_value[i] specifies the value of the i-th quality metric. When the value of the syntax element pqm_type is 0, the stored 16-bit unsigned integer pqm_value is interpreted as a PSNR value (in dB) (expressed as floating point) as follows, with the exception of PSNR equal to infinity for values ​​of pqm_value equal to 0:

[0129]

number

[0130] where M is an integer (e.g., 100).

[0131]

[0128] When the value of the syntax element pqm_type is 1, the stored 16-bit unsigned integer pqm_value is interpreted as a wPSNR value (in dB) (expressed in floating point) as follows, with the exception of wPSNR equal to infinity for values ​​of pqm_value equal to 0:

[0132]

number

[0133] where M is an integer (e.g., 100).

[0134]

[0129] When the value of the syntax element pqm_type is 2, the stored 16-bit unsigned integer pqm_value is interpreted as a WS-PSNR value (in dB) (expressed as floating point) as follows, with the exception of WS-PSNR equal to infinity for values ​​of pqm_value equal to 0:

[0135]

number

[0136] where M is an integer (e.g., 100).

[0137] When the syntax element pqm_type has a value of 3, the quality metric indicates the average luma PSNR of the CLVS to which the associated picture belongs. The 16-bit unsigned integer pqm_value is interpreted as the result of the sequence-level PSNR quality metric (dB), derived as follows (expressed in floating point): with the exception of PSNR equal to infinity for values ​​of pqm_value equal to 0.

[0138]

number

[0139] where M is an integer (e.g., 100).

[0140]

[0131] When the syntax element pqm_type has the value 4, the quality metric indicates the average luma-weighted PSNR of the CLVS to which the associated picture belongs. The 16-bit unsigned integer pqm_value is interpreted as a sequence-level wPSNR value (in dB) (expressed in floating point) as follows, with the exception of wPSNR equal to infinity for values ​​of pqm_value equal to 0:

[0141]

number

[0142] where M is an integer (e.g., 100).

[0143]

[0132] When the syntax element pqm_type has a value of 5, the quality metric indicates the average luma WS-PSNR of the CLVS to which the associated picture belongs. The 16-bit unsigned integer pqm_value is interpreted as a sequence-level WS-PSNR value (in dB) as follows (expressed in floating point), with the exception of WS-PSNR equal to infinity for values ​​of pqm_value equal to 0:

[0144]

number

[0145] where M is an integer (e.g., 100).

[0146]

[0133] In another example, an additional quality metric type may be included in the SEI message to indicate an average quality metric applied to multiple video frames. A first syntax element may be specified in the SEI message to indicate that the quality metric specified in the SEI message applies to the associated picture and persists for all subsequent pictures of the current layer in the output order. A second syntax element may be specified in the SEI message to cancel the persistence of any previous quality metric in the output order.

[0147] In another example, when an average quality metric such as sequence-level PSNR exists for any picture of a CLVS, an associated picture quality SEI message shall exist for the first picture of the CLVS. The average picture metrics of all SEI messages that apply to the same CLVS shall have the same content.

[0148]

[0135] Figure 5 is a flowchart showing an example process for coding a quality metrics supplemental enhancement information message. Figure 5 illustrates both the encoding process and the decoding process of the present disclosure. As shown in Figure 5, the encoding process may be performed by a source device 102 including a video encoder 200. The decoding process may be performed by a destination device 116 including a video decoder 300.

[0149] In one example of the disclosure, the source device 102 may be configured to receive a picture (500). The source device 102 may be further configured to encode the picture (e.g., with the video encoder 200) and transmit the encoded video bitstream to the destination device 116. The source device 102 may be further configured to determine a quality metric for the picture (502). The source device 102 may be further configured to encode a quality metric message including a quality metric syntax element, where the quality metric syntax element indicates a value of a quality metric related to the picture (504).

[0150] In yet another example of the present disclosure, the source device 102 may be further configured to encode a quality metric type syntax element in the quality metrics message, where the quality metric type syntax element indicates a type of quality metric indicated by the quality metric syntax element among the multiple types of quality metrics. In one example, the multiple types of quality metrics include a peak signal-to-noise ratio (PSNR). In another example, the multiple types of quality metrics include two or more of a peak signal-to-noise ratio (PSNR), a structural similarity index (SSIM), a multiscale structural similarity index (MS-SSIM), a video quality metric (VQM), a weighted PSNR (wPSNR), a spherically uniform weighted PSNR (WS-PSNR), a sequence PSNR, a sequence wPSNR, or a sequence WS-PSNR. In the above example, the quality metrics syntax element indicates the value of the quality metric indicated by the quality metrics type syntax element.

[0151]

[0138] The destination device 116 may be configured to receive a picture (510). The destination device 116 may further be configured to decode the picture (e.g., using the video decoder 300). The destination device 116 may also decode a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture (512). The destination device 116 may further be configured to apply a post-processing technique to the picture according to the value of the quality metric to form a processed picture (514), and display the processed picture (516).

[0152]

[0139] In yet another example of the present disclosure, the destination device 116 may be further configured to decode a quality metric type syntax element in the quality metrics message, where the quality metric type syntax element indicates a type of quality metric indicated by the quality metric syntax element among the types of multiple quality metrics. In one example, the types of multiple quality metrics include a peak signal-to-noise ratio (PSNR). In another example, the types of multiple quality metrics include two or more of a peak signal-to-noise ratio (PSNR), a structural similarity index (SSIM), a multi-scale structural similarity index (MS-SSIM), a video quality metric (VQM), a weighted PSNR (wPSNR), a spherically uniform weighted PSNR (WS-PSNR), a sequence PSNR, a sequence wPSNR, or a sequence WS-PSNR. In the above example, the quality metric syntax element indicates a value of the quality metric indicated by the quality metric type syntax element.

[0153] In one example of the present disclosure, the quality metrics message comprises a quality metrics SEI message. In another example, the quality metrics message comprises a quality metrics open bitstream unit (OBU).

[0154]

[0141] In other examples of the present disclosure, the source device 102 and / or the destination device 116 may be configured to code a second quality metrics message including a second quality metric syntax element, where the second quality metric syntax element indicates a second value of a second quality metric relating to a sub-picture or region of interest of the picture.

[0155] For illustrative purposes, the techniques above are described in the context of VVC (ITU-T H.266 under development) and HEVC (ITU-T H.265). However, the techniques of this disclosure may be implemented by video encoding devices configured for other video coding standards and formats, such as AV1, future versions of AV1, and successors of the AV1 video coding format. For example, the message, as opposed to an SEI message, may be packetized data such as an open bitstream unit (OBU) that includes at least some of the metadata described in this disclosure. As one example, some or all of the above-described syntax included in the picture orientation SEI message may be included in the picture orientation OBU, such that the picture orientation OBU includes one or more of a cancel flag, a persistence flag, a component picture match flag, or a transform type syntax element. As another example, some or all of the syntax described above included in the picture quality metrics SEI message may be included in the picture quality metrics OBU such that the picture quality metrics OBU includes one or more syntax elements that indicate quality metrics for the picture.

[0156]

[0143] Figure 6 is a block diagram illustrating an example video encoder 200 that may implement the techniques of this disclosure. Figure 6 is provided for illustrative purposes and should not be considered as limiting the techniques broadly illustrated and described in this disclosure. For illustrative purposes, this disclosure describes the video encoder 200 according to the techniques of VVC (ITU-T H.266 under development) and HEVC (ITU-T H.265). However, the techniques of this disclosure may be implemented by video encoding devices configured for other video coding standards and video coding formats, such as AV1 and successors of the AV1 video coding format.

[0157] 6, the video encoder 200 includes a video data memory 230, a mode selection unit 202, a residual generation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a filter unit 216, a decoded picture buffer (DPB) 218, and an entropy coding unit 220. Any or all of the video data memory 230, the mode selection unit 202, the residual generation unit 204, the transform processing unit 206, the quantization unit 208, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the filter unit 216, the DPB 218, and the entropy coding unit 220 may be implemented in one or more processors or processing circuits. For example, the units of the video encoder 200 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, an ASIC, or an FPGA. Moreover, video encoder 200 may include additional or alternative processors or processing circuitry for performing these and other functions.

[0158]

[0145] The video data memory 230 may store video data to be encoded by components of the video encoder 200. The video encoder 200 may receive video data stored in the video data memory 230, for example, from the video source 104 (FIG. 1). The DPB 218 may act as a reference picture memory that stores reference video data for use in predicting subsequent video data by the video encoder 200. The video data memory 230 and the DPB 218 may be formed by any of a variety of memory devices, such as synchronous dynamic random access memory (DRAM), including DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The video data memory 230 and the DPB 218 may be provided by the same memory device or separate memory devices. In various examples, the video data memory 230 may be on-chip with other components of the video encoder 200, as shown, or off-chip relative to those components.

[0159] In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to video encoder 200 unless specifically so described, or to memory external to video encoder 200 unless specifically so described. Instead, references to video data memory 230 should be understood as a reference memory that stores video data that video encoder 200 receives for encoding (e.g., video data for a current block to be encoded). Memory 106 of FIG. 1 may also provide temporary storage of outputs from various units of video encoder 200.

[0160]

[0147] The various units in FIG. 6 are shown to aid 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 preset with respect to the operations that may be performed. A programmable circuit refers to a circuit that may be programmed to perform various tasks and provide flexible functionality in the operations that may be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by the software or firmware instructions. A fixed-function circuit may execute software instructions (e.g., to receive parameters or output parameters), but the type of operations that the fixed-function circuit performs is generally invariant. In some examples, one or more of the units may be separate circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be an integrated circuit.

[0161]

[0148] The video encoder 200 may include an arithmetic logic unit (ALU), a basic functional unit (EFU), a programmable core formed of digital circuits, analog circuits, and / or programmable circuits. In examples in which the operations of the video encoder 200 are implemented using software executed by a programmable circuit, the memory 106 (FIG. 1) may store instructions (e.g., object code) of the software that the video encoder 200 receives and executes, or another memory (not shown) within the video encoder 200 may store such instructions.

[0162]

[0149] The video data memory 230 is configured to store the received video data. The video encoder 200 may retrieve pictures of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 may be raw video data to be encoded.

[0163] The mode selection unit 202 includes a motion estimation unit 222, a motion compensation unit 224, and an intra prediction unit 226. The mode selection unit 202 may include additional functional units for performing video prediction according to other prediction modes. By way of 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.

[0164]

[0151] The mode selection unit 202 generally coordinates multiple encoding passes to test combinations of encoding parameters and the resulting rate-distortion values ​​for such combinations. The encoding parameters may include partitioning of CTUs into CUs, prediction modes for CUs, transform types for residual data of CUs, quantization parameters for residual data of CUs, etc. The mode selection unit 202 may finally select a combination of encoding parameters that has a rate-distortion value that is better than other tested combinations.

[0165]

[0152] The video encoder 200 may partition a picture retrieved from the video data memory 230 into a series of CTUs and encapsulate one or more CTUs in a slice. The mode selection unit 202 may partition the CTUs of the picture according to a tree structure, such as the MTT structure, QTBT structure, superblock structure, or quadtree structure described above. As described above, the video encoder 200 may form one or more CUs from partitioning the CTUs according to the tree structure. Such a CU may also be generally referred to as a "video block" or a "block."

[0166]

[0153] In general, the mode selection unit 202 also controls its components (e.g., the motion estimation unit 222, the motion compensation unit 224, and the intra prediction unit 226) to generate a prediction block for a current block (e.g., the current CU, or in HEVC, the overlapping portion of the PU and TU). For inter prediction of the current block, the motion estimation unit 222 may perform motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in the DPB 218). In particular, the motion estimation unit 222 may calculate a value representing how similar a potential reference block is to the current block according to, for example, a sum of absolute differences (SAD), a sum of squared differences (SSD), a mean absolute difference (MAD), a mean squared difference (MSD), etc. The motion estimation unit 222 may generally perform these calculations using a sample-by-sample difference between the current block and the reference block under consideration. Motion estimation unit 222 may identify the reference block having the lowest value resulting from these calculations, which indicates the reference block that most closely matches the current block.

[0167]

[0154] The motion estimation unit 222 may form one or more motion vectors (MVs) that define the position of a reference block in a reference picture relative to the position of a current block in a current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, in unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while in bidirectional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then use the motion vectors to generate a predictive block. For example, the motion compensation unit 224 may use the motion vectors to retrieve data of a reference block. As another example, if the motion vector has partial sample precision, the motion compensation unit 224 may interpolate values ​​for the predictive block according to one or more interpolation filters. Moreover, in bidirectional inter prediction, the motion compensation unit 224 may retrieve data for two reference blocks identified by the respective motion vectors and combine the retrieved data, for example, through sample-wise averaging or weighted averaging.

[0168]

[0155] When operating according to the AV1 video coding format, the motion estimation unit 222 and the motion compensation unit 224 may be configured to encode coding blocks of video data (e.g., both luma coding blocks and chroma coding blocks) using translational motion compensation, affine motion compensation, overlapped block motion compensation (OBMC), and / or compound inter / intra prediction.

[0169]

[0156] As another example, for intra prediction, or intra predictive coding, the intra prediction unit 226 may generate a predictive block from samples adjacent to a current block. For example, in a directional mode, the intra prediction unit 226 may generally mathematically combine values ​​of adjacent samples to produce a predictive block and populate these calculated values ​​in a defined direction across the current block. As another example, in a DC mode, the intra prediction unit 226 may calculate an average of the adjacent samples for the current block and generate a predictive block to include this obtained average for each sample of the predictive block.

[0170] When operating according to the AV1 video coding format, the intra prediction unit 226 may be configured to encode coding blocks of video data (e.g., both luma coding blocks and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, chroma-from-luma (CFL) prediction, intra block copy (IBC), and / or color palette modes. The mode selection unit 202 may include additional functional units for performing video prediction according to other prediction modes.

[0171]

[0158] The mode selection unit 202 provides the prediction block to the residual generation unit 204. The residual generation unit 204 receives a raw uncoded version of the current block from the video data memory 230 and receives the prediction block from the mode selection unit 202. The residual generation unit 204 calculates sample-by-sample differences between the current block and the prediction block. The resulting sample-by-sample differences define a residual block for the current block. In some examples, the residual generation unit 204 may also determine differences between sample values ​​in the residual block to generate the residual block using residual differential pulse code modulation (RDPCM). In some examples, the residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

[0172]

[0159] In an example where the mode selection unit 202 partitions a 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 having 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 2N×2N, the video encoder 200 may support a PU size of 2N×2N or N×N for intra prediction, and a symmetric PU size of 2N×2N, 2N×N, N×2N, N×N, or the like for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning for PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N for inter prediction.

[0173] In an example in which the mode selection unit 202 does not further partition the CU into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As described above, the size of a CU may refer to the size of the luma coding block of the CU. The video encoder 200 and the video decoder 300 may support CU sizes of 2N×2N, 2N×N, or N×2N.

[0174]

[0161] In other video coding techniques, such as intra block copy mode coding, affine mode coding, and linear model (LM) mode coding, as some examples, the mode selection unit 202 generates a predictive block for the current block being coded via a respective unit associated with the coding technique. In some examples, such as palette mode coding, the mode selection unit 202 may not generate a predictive block, but instead generate a syntax element that indicates how the block should be reconstructed based on a selected palette. In such modes, the mode selection unit 202 may provide these syntax elements to be coded to the entropy coding unit 220.

[0175]

[0162] As described above, the residual generation unit 204 receives the video data for a current block and the corresponding predictive 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 sample-by-sample differences between the predictive block and the current block.

[0176]

[0163] 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"). Transform processing unit 206 may apply various transforms to the residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, transform processing unit 206 may perform multiple transforms on the residual block, e.g., a linear transform and a secondary transform, such as a rotation transform. In some examples, transform processing unit 206 does not apply a transform to the residual block.

[0177]

[0164] When operating according to AV1, transform processing unit 206 may apply one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "transform coefficient block"). Transform processing unit 206 may apply various transforms to the residual block to form the transform coefficient block. For example, transform processing unit 206 may apply a combination of horizontal / vertical transforms, which may include a discrete cosine transform (DCT), an asymmetric discrete sine transform (ADST), a flipped ADST (e.g., an ADST in reverse order), and an identity transform (IDTX). When using an identity transform, the transform is skipped in one of the vertical or horizontal directions. In some examples, the transform process may be skipped.

[0178]

[0165] 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 result in loss of information, and thus the quantized transform coefficients may have lower precision than the original transform coefficients produced by the transform processing unit 206.

[0179]

[0166] The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform to the quantized transform coefficient block, respectively, to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may produce a reconstructed block corresponding to the current block (potentially with some distortion) based on the reconstructed residual block and the predictive 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 predictive block generated by the mode selection unit 202 to produce a reconstructed block.

[0180]

[0167] 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 blockiness artifacts along the edges of a CU. The operations of filter unit 216 may be skipped in some examples.

[0181]

[0168] When operating according to AV1, 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 blockiness artifacts along the edges of a CU. In another example, filter unit 216 may apply a conditional directional emphasis filter (CDEF), which may be applied after deblocking, and may include application of a non-separable nonlinear low-pass directional filter based on an estimated edge direction. Filter unit 216 may also include a loop restoration filter, which may be applied after CDEF, and may include a separable symmetric normalized Wiener filter or a dual self-guided filter.

[0182]

[0169] The video encoder 200 stores the reconstructed block in the DPB 218. For example, in an example where the operation of the filter unit 216 is not performed, the reconstruction unit 214 may store the reconstructed block in the DPB 218. In an example where the operation of the filter unit 216 is performed, the filter unit 216 may store the filtered reconstructed block in the DPB 218. The motion estimation unit 222 and the motion compensation unit 224 may retrieve a reference picture formed from the reconstructed (and potentially filtered) block from the DPB 218 to inter predict blocks of a picture to be subsequently encoded. Furthermore, the intra prediction unit 226 may use the reconstructed block in the DPB 218 of the current picture to intra predict other blocks in the current picture.

[0183] In general, the entropy encoding unit 220 may entropy encode syntax elements received from other functional components of the video encoder 200. For example, the entropy encoding unit 220 may entropy encode quantized transform coefficient blocks from the quantization unit 208. As another example, the entropy encoding unit 220 may entropy encode predictive syntax elements (e.g., motion information for inter prediction, or intra mode information for intra prediction) from the mode selection unit 202. The entropy encoding unit 220 may perform one or more entropy encoding operations on syntax elements, which are another example of video data, to generate entropy encoded data. For example, the entropy encoding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2V) length coding operation, a syntax-based context-adaptive binary arithmetic coding (SBAC) operation, a probability interval partitioned entropy (PIPE) coding operation, an exponential-Golomb coding operation, or another type of entropy coding operation on the data. In some examples, the entropy encoding unit 220 may operate in a bypass mode in which syntax elements are not entropy coded.

[0184]

[0171] Video encoder 200 may output a bitstream that includes entropy-encoded syntax elements needed to reconstruct blocks of a slice or picture. In particular, entropy encoding unit 220 may output the bitstream.

[0185]

[0172] According to AV1, the entropy coding unit 220 may be configured as a symbol-to-symbol adaptive multi-symbol arithmetic coder. The AV1 syntax elements include an alphabet of N elements, and the context (e.g., a probability model) includes a set of N probabilities. The entropy coding unit 220 may store these probabilities as an n-bit (e.g., 15-bit) cumulative distribution function (CDF). The entropy coding unit 22 may also perform recursive scaling with an update factor based on the alphabet size to update the context.

[0186]

[0173] The operations described above are described with respect to blocks. Such descriptions should be understood as operations for luma coding blocks and / or chroma coding blocks. As described above, in some examples, the luma coding block and the chroma coding block are the luma component and the chroma component of a CU. In some examples, the luma coding block and the chroma coding block are the luma component and the chroma component of a PU.

[0187]

[0174] In some examples, operations performed with respect to luma coding blocks do not need to be repeated for chroma coding blocks. As an example, operations for identifying motion vectors (MVs) and reference pictures for luma coding blocks do not need to be repeated to identify MVs and reference pictures for chroma blocks. Rather, MVs for luma coding blocks may be scaled to determine MVs for chroma blocks, and the reference pictures may be the same. As another example, the intra prediction process may be the same for luma coding blocks and chroma coding blocks.

[0188]

[0175] According to the SEI technique described above, video encoder 200 represents an example of a device configured to encode video data, including a memory configured to store video data, and one or more processing units implemented in a circuit configured to receive a picture and encode a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture. Video encoder 200 may also be further configured to encode a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture.

[0189]

[0176] Figure 7 is a block diagram illustrating an example video decoder 300 that may implement the techniques of this disclosure. Figure 7 is provided for illustrative purposes and is not intended to limit the techniques broadly illustrated and described in this disclosure. For illustrative purposes, this disclosure describes the video decoder 300 in accordance with VVC (ITU-T H.266 under development) and HEVC (ITU-T H.265) techniques. However, the techniques of this disclosure may be implemented by video coding devices configured for other video coding standards.

[0190] In the example of FIG. 7, the video decoder 300 includes a coded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a filter unit 312, and a decoded picture buffer (DPB) 314. Any or all of the CPB memory 320, the entropy decoding unit 302, the prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, the filter unit 312, and the DPB 314 may be implemented in one or more processors or processing circuits. For example, the units of the 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, an ASIC, or an FPGA. Moreover, the video decoder 300 may include additional or alternative processors or processing circuits for performing these and other functions.

[0191]

[0178] 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 for performing prediction according to other prediction modes. By way of 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.

[0192] When operating according to AV1, the compensation unit 316 may be configured to decode coding blocks of the video data (e.g., both luma and chroma coding blocks) using translational motion compensation, affine motion compensation, OBMC, and / or compound inter / intra prediction, as described above. The intra prediction unit 318 may be configured to decode coding blocks of the video data (e.g., both luma and chroma coding blocks) using directional intra prediction, non-directional intra prediction, recursive filter intra prediction, CFL, intra block copy (IBC), and / or color palette mode, as described above.

[0193]

[0180] The CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of the video decoder 300. The video data stored in the CPB memory 320 may be obtained, for example, from the computer-readable medium 110 (FIG. 1). The CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from the encoded video bitstream. The CPB memory 320 may also store video data other than syntax elements of a coded picture, such as temporary data representing output from various units of the video decoder 300. The DPB 314 generally stores decoded pictures that the video decoder 300 may output and / or use as reference video data when decoding subsequent data or pictures of the encoded video bitstream. The CPB memory 320 and the DPB 314 may be formed by any of a variety of memory devices, such as DRAM, including SDRAM, MRAM, RRAM, or other types of memory devices. The CPB memory 320 and the DPB 314 may be provided by the same memory device or separate memory devices. In various examples, the CPB memory 320 may be on-chip with other components of the video decoder 300 or off-chip relative to those components.

[0194] Additionally or alternatively, in some examples, the video decoder 300 may retrieve coded video data from memory 120 (FIG. 1). That is, memory 120 may store data as described above along with CPB memory 320. Similarly, memory 120 may store instructions to be executed by the video decoder 300 when some or all of the functionality of the video decoder 300 is implemented in software to be executed by processing circuitry of the video decoder 300.

[0195]

[0182] The various units shown in FIG. 7 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. As in FIG. 6, a fixed-function circuit refers to a circuit that provides a specific function and is preset with respect to the operations that may be performed. A programmable circuit refers to a circuit that may be programmed to perform various tasks and provide flexible functionality in the operations that may be performed. For example, a programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by the software or firmware instructions. Although a fixed-function circuit may execute software instructions (e.g., to receive parameters or output parameters), the type of operation that the fixed-function circuit performs is generally invariant. In some examples, one or more of the units may be separate circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be an integrated circuit.

[0196]

[0183] The video decoder 300 may include a programmable core formed from an ALU, an EFU, digital circuits, analog circuits, and / or programmable circuits. In examples in which the operation of the video decoder 300 is performed by software executing on a programmable circuit, on-chip or off-chip memory may store instructions (e.g., object code) of the software that the video decoder 300 receives and executes.

[0197]

[0184] The entropy decoding unit 302 may receive the encoded video data from the CPB and entropy decode the video data to recover the syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.

[0198]

[0185] Generally, 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 (wherein the block currently being reconstructed, i.e., decoded, may be referred to as the "current block").

[0199]

[0186] The entropy decoding unit 302 may entropy decode syntax elements defining the quantized transform coefficients of the quantized transform coefficient block, as well as transform information such as a quantization parameter (QP) and / or a transform mode indication(s). The inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine the degree of quantization and, similarly, the degree of inverse quantization that the inverse quantization unit 306 should apply. The inverse quantization unit 306 may perform, for example, a bitwise left shift operation to inverse quantize the quantized transform coefficients. The inverse quantization unit 306 may thereby form a transform coefficient block including the transform coefficients.

[0200] After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse transform, or another inverse transform to the transform coefficient block.

[0201]

[0188] Furthermore, the prediction processing unit 304 generates a prediction block according to the prediction information syntax element entropy decoded by the entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter-predicted, the motion compensation unit 316 may generate a prediction block. In this case, the prediction information syntax element may indicate a reference picture in the DPB 314 from which the reference block should be retrieved, as well as a motion vector that identifies the location of the reference block in the reference picture relative to the location of the current block in the current picture. The motion compensation unit 316 may generally perform an inter-prediction process in a manner substantially similar to that described with respect to the motion compensation unit 224 (FIG. 6).

[0202]

[0189] 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 perform an intra prediction process in a manner substantially similar to that described with respect to the intra prediction unit 226 (FIG. 6). The intra prediction unit 318 may retrieve data of neighboring samples for the current block from the DPB 314.

[0203]

[0190] The reconstruction unit 310 may reconstruct the current block using the predictive block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the predictive block to reconstruct the current block.

[0204]

[0191] Filter unit 312 may perform one or more filter operations on the reconstructed block. For example, filter unit 312 may perform a deblocking operation to reduce blockiness artifacts along edges of the reconstructed block. The operations of filter unit 312 are not necessarily performed in all examples.

[0205]

[0192] The video decoder 300 may store the reconstructed block in the DPB 314. For example, in an example where the operation of the filter unit 312 is not performed, the reconstruction unit 310 may store the reconstructed block in the DPB 314. In an example where the operation of the filter unit 312 is performed, the filter unit 312 may store the filtered reconstructed block in the DPB 314. As described above, the DPB 314 may provide reference information to the prediction processing unit 304, such as samples of a current picture for intra prediction and previously decoded pictures for subsequent motion compensation. Moreover, the video decoder 300 may output the decoded picture (e.g., decoded video) from the DPB 314 for subsequent presentation on a display device, such as the display device 118 of FIG. 1.

[0206]

[0193] In accordance with the SEI techniques described above, the video decoder 300 represents an example of a device configured to decode video data, including a memory configured to store video data, and one or more processing units implemented in a circuit configured to receive a picture and decode a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture. The video decoder 300 may also be further configured to decode a quality metrics message including a quality metrics syntax element, where the quality metrics syntax element indicates a value of a quality metric related to the picture.

[0207]

[0194] Figure 8 is a flowchart illustrating an example method for encoding a current block according to the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video encoder 200 (Figures 1 and 6), it should be understood that other devices may be configured to perform a method similar to that of Figure 8.

[0208]

[0195] In this example, the video encoder 200 first predicts the current block (350). For example, the video encoder 200 may form a predictive 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 a difference between an original uncoded block and a predictive block for the current block. The video encoder 200 may then transform the residual block and quantize transform coefficients of the residual block (354). The video encoder 200 may then scan the quantized transform coefficients of the residual block (356). During or following the scan, the video encoder 200 may entropy code the transform coefficients (358). For example, the video encoder 200 may code the transform coefficients using CAVLC or CABAC. The video encoder 200 may then output entropy coded data for the block (360).

[0209]

[0196] Figure 9 is a flowchart illustrating an example method for decoding a current block of video data in accordance with the techniques of this disclosure. The current block may comprise a current CU. Although described with respect to video decoder 300 (Figures 1 and 7), it should be understood that other devices may be configured to perform a method similar to that of Figure 9.

[0210]

[0197] The video decoder 300 may receive entropy coded data for the current block, such as entropy coded prediction information and entropy coded data for transform coefficients of a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy coded data to determine prediction information for the current block and to reconstruct transform coefficients of the residual block (372). The video decoder 300 may predict the current block, e.g., using an intra-prediction or inter-prediction mode indicated by the prediction information for the current block, to compute a predictive block for the current block (374). The video decoder 300 may then inverse scan the reconstructed transform coefficients to create a block of quantized transform coefficients (376). The video decoder 300 may then dequantize the transform coefficients and apply an inverse transform to the transform coefficients to produce a residual block (378). The video decoder 300 may finally decode the current block by combining the predictive block and the residual block (380).

[0211]

[0198] Other exemplary aspects of the techniques and devices of the present disclosure are described below.

[0212]

[0199] Aspect 1A - A method for processing video data, comprising receiving a picture, and coding a picture orientation supplemental enhancement information (SEI) message including one or more of a cancel flag, a persistence flag, a component picture match flag, or a transform type syntax element, wherein the transform type syntax element indicates one or more of a rotation or mirroring applied to the picture.

[0213]

[0200] Aspect 2A - The method of aspect 1A, wherein the coding comprises decoding, and the method further comprises processing the picture according to a picture orientation SEI message.

[0214]

[0201] Aspect 3A - The method of aspect 1A or aspect 2A, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0215]

[0202] Aspect 4A - The method of aspect 1A or aspect 2A, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0216]

[0203] Aspect 5A - The method of claim 1A, wherein the coding comprises encoding.

[0217]

[0204] Aspect 6A - A method for processing video data, comprising receiving a picture and coding a picture quality metrics supplemental enhancement information (SEI) message including one or more syntax elements indicating quality metrics of the picture.

[0218]

[0205] Aspect 7A - The method of aspect 6A, wherein the coding comprises decoding, and the method further comprises processing the picture according to the picture quality metrics SEI message.

[0219]

[0206] Aspect 8A - The method of aspect 6A or aspect 7A, wherein the picture orientation message comprises a picture quality metrics supplemental enhancement information (SEI) message.

[0220]

[0207] Aspect 9A - The method of any of aspects 6A to 8A, wherein the picture quality metrics message comprises one or more syntax elements indicating quality metrics of one or more sub-pictures or regions of interest of a picture associated with the picture quality metrics message.

[0221]

[0208] Aspect 10A--The method of aspect 9A, wherein the one or more syntax elements indicate quality metrics for high dynamic range (HDR) or 360 video content.

[0222]

[0209] Example 11A - The method of any of Examples 6A to 10A, wherein the coding comprises encoding.

[0223]

[0210] Embodiment 12A - Any combination of the methods of Embodiment 1A through Embodiment 10A.

[0224] Aspect 13A. A device for processing video data, the device comprising one or more means for performing a method as described in any of aspects 1A to 12A.

[0225]

[0212] Aspect 14A. The device of aspect 13A, wherein the one or more means comprises one or more processors implemented in circuitry.

[0226]

[0213] Aspect 15A. A device described in any of aspects 13A and 14A, further comprising a memory for storing video data.

[0227] Aspect 16A. The device of any of aspects 13A to 15A, further comprising a display configured to display the decoded video data.

[0228]

[0215] Aspect 17A: A device described in any of aspects 13A to 16A, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

[0229]

[0216] Aspect 18A: A device described in any of aspects 13A to 17A, wherein the device comprises a video decoder.

[0230]

[0217] Aspect 19A: A device described in any of aspects 13A to 18A, wherein the device comprises a video encoder.

[0231]

[0218] Aspect 20A - A computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors to perform any of the methods of aspects 1A to 12A.

[0232]

[0219] Aspect 1B - A method for processing video data, comprising receiving a picture and coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0233]

[0220] Embodiment 2B - The method of embodiment 1B, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0234]

[0221] Embodiment 3B - The method of embodiment 1B, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0235]

[0222] Aspect 4B - The method of aspect 1B, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0236]

[0223] Aspect 5B - The method of aspect 1B, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

[0237]

[0224] Aspect 6B - The method of aspect 1B, wherein coding comprises decoding, and the method further comprises applying a transform to the picture in accordance with a transform type syntax element to form a transformed picture, and displaying the transformed picture.

[0238]

[0225] Aspect 7B - The method of aspect 1B, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0239]

[0226] Aspect 8B - The method of aspect 1B, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0240]

[0227] Aspect 9B - An apparatus configured to process video data, comprising: a memory configured to store a picture; and one or more processors implemented in a circuit and in communication with the memory, wherein the one or more processors are configured to receive a picture; and code a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0241]

[0228] Embodiment 10B - The apparatus of embodiment 9B, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0242]

[0229] Example 11B - The apparatus of example 9B, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0243]

[0230] Aspect 12B - The apparatus of aspect 9B, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0244]

[0231] Aspect 13B - The apparatus of aspect 9B, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message is applied to a subsequent picture.

[0245]

[0232] Aspect 14B - The apparatus of aspect 9B, wherein the apparatus is configured to decode a picture orientation message, and the one or more processors are further configured to apply a transform to the picture in accordance with a transform type syntax element to form a transformed picture, and display the transformed picture.

[0246]

[0233] Aspect 15B - The apparatus of aspect 9B, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0247]

[0234] Example 16B - The apparatus of example 9B, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0248]

[0235] Aspect 17B - An apparatus configured to process video data, comprising: means for receiving a picture; and means for coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0249]

[0236] Example 18B - The apparatus of example 17B, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0250]

[0237] Example 19B - The apparatus of example 17B, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0251]

[0238] Aspect 20B - The apparatus of aspect 17B, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0252]

[0239] Aspect 21B - The apparatus of aspect 17B, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message is applied to a subsequent picture.

[0253]

[0240] Aspect 22B - The apparatus of aspect 17B, wherein the means for coding comprises means for decoding, and the apparatus further comprises means for applying a transform to the picture in accordance with the transform type syntax element to form a transformed picture, and means for displaying the transformed picture.

[0254]

[0241] Aspect 23B - The apparatus of aspect 17B, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0255]

[0242] Example 24B - The apparatus of example 17B, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0256]

[0243] Aspect 25B - A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to process video data to receive a picture and code a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0257]

[0244] Aspect 26B - The non-transitory computer-readable storage medium of aspect 25B, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0258]

[0245] Example 27B - A non-transitory computer-readable storage medium of example 25B, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0259]

[0246] Aspect 28B - The non-transitory computer-readable storage medium of aspect 25B, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0260]

[0247] Aspect 29B - A non-transitory computer-readable storage medium of aspect 25B, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message is applied to a subsequent picture.

[0261]

[0248] Aspect 30B - A non-transitory computer-readable storage medium of aspect 25B, wherein the device is configured to decode the picture orientation message and the instructions further cause one or more processors to apply a transform to the picture in accordance with the transform type syntax element to form a transformed picture and display the transformed picture.

[0262]

[0249] Aspect 31B - The non-transitory computer-readable storage medium of aspect 25B, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0263]

[0250] Aspect 32B - The non-transitory computer-readable storage medium of aspect 25B, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0264]

[0251] Aspect 1C - A method for processing video data, comprising receiving a picture and coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0265]

[0252] Embodiment 2C - The method of embodiment 1C, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0266]

[0253] Embodiment 3C - The method of embodiment 1C, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0267]

[0254] Aspect 4C - The method of any of aspects 1C to 3C, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0268]

[0255] Aspect 5C - A method of any of aspects 1C to 4C, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

[0269]

[0256] Aspect 6C - A method of any of aspects 1C to 5C, wherein coding comprises decoding, and the method further comprises applying a transform to the picture in accordance with a transform type syntax element to form a transformed picture, and displaying the transformed picture.

[0270]

[0257] Aspect 7C - The method of any of aspects 1C to 6C, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0271]

[0258] Aspect 8C - The method of any of aspects 1C to 6C, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0272]

[0259] Aspect 9C - An apparatus configured to process video data, comprising: a memory configured to store a picture; and one or more processors implemented in a circuit and in communication with the memory, wherein the one or more processors are configured to receive a picture; and code a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0273]

[0260] Embodiment 10C - The apparatus of embodiment 9C, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0274]

[0261] Example 11C - The apparatus of example 9C, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0275]

[0262] Aspect 12C - The apparatus of any of aspects 9C to 11C, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0276]

[0263] Aspect 13C - The apparatus of any of aspects 9C to 12C, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

[0277]

[0264] Aspect 14C - An apparatus of any of aspects 9C to 13C, wherein the apparatus is configured to decode a picture orientation message, and the one or more processors are further configured to apply a transform to the picture in accordance with a transform type syntax element to form a transformed picture, and display the transformed picture.

[0278]

[0265] Aspect 15C - The apparatus of any of aspects 9C to 14C, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0279]

[0266] Example 16C - The apparatus of any of examples 9C to 14C, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0280]

[0267] Aspect 17C - An apparatus configured to process video data, comprising: means for receiving a picture; and means for coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform among a plurality of transforms to be applied to the picture.

[0281]

[0268] Embodiment 18C - The apparatus of embodiment 17C, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0282]

[0269] Example 19C - The apparatus of example 17C, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0283]

[0270] Aspect 20C - The apparatus of any of aspects 17C to 19C, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0284]

[0271] Aspect 21C - An apparatus of any of aspects 17C to 20C, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

[0285]

[0272] Aspect 22C - An apparatus of any of aspects 17C to 21C, wherein the means for coding comprises means for decoding, and the apparatus further comprises means for applying a transform to the picture in accordance with the transform type syntax element to form a transformed picture, and means for displaying the transformed picture.

[0286]

[0273] Aspect 23C - The apparatus of any of aspects 17C to 22C, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0287]

[0274] Example 24C - The apparatus of any of examples 17C to 22C, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0288]

[0275] Aspect 25C - A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to process video data to receive a picture and code a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform, among a plurality of transforms, to be applied to the picture.

[0289]

[0276] Example 26C - The non-transitory computer-readable storage medium of example 25C, wherein the plurality of transformations includes two or more of a rotation transformation, a mirroring transformation, or a combination of a rotation transformation and a mirroring transformation.

[0290]

[0277] Example 27C - A non-transitory computer-readable storage medium of example 25C, wherein the multiple transforms include a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising a 180 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by a horizontal mirroring transformation, a fifth transform comprising a 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by a horizontal mirroring transformation, and a seventh transform comprising a 270 degree counterclockwise transformation.

[0291]

[0278] Aspect 28C - The non-transitory computer-readable storage medium of any of aspects 25C to 27C, wherein the transform type syntax element further includes a value indicating that no transform is applied.

[0292]

[0279] Aspect 29C - A non-transitory computer-readable storage medium of any of aspects 25C to 28C, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

[0293]

[0280] Aspect 30C - A non-transitory computer-readable storage medium of any of aspects 25C to 29C, wherein the device is configured to decode the picture orientation message and the instructions further cause one or more processors to apply a transform to the picture in accordance with the transform type syntax element to form a transformed picture and display the transformed picture.

[0294]

[0281] Aspect 31C - The non-transitory computer-readable storage medium of any of aspects 25C to 30C, wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

[0295]

[0282] Aspect 32C - The non-transitory computer-readable storage medium of any of aspects 25C to 30C, wherein the picture orientation message comprises a picture orientation open bitstream unit (OBU).

[0296]

[0283] In accordance with the above examples, it should be recognized that some acts or events of any of the techniques described herein may be performed in a different sequence, added, merged, or omitted entirely (e.g., not all described acts or events are necessary to the practice of the techniques). Moreover, in some examples, acts or events may be performed simultaneously rather than sequentially, for example, through multi-threaded processing, interrupt processing, or multiple processors.

[0297]

[0284] In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or codes and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium, such as a data storage medium, or may include a communication medium, which includes any medium that enables the transfer of a computer program from one place to another, for example, according to a communication protocol. In this manner, the computer-readable medium may generally correspond to (1) a tangible computer-readable storage medium that is non-transitory, or (2) a communication medium, such as a signal or carrier wave. The data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes and / or data structures for implementation of the techniques described in this disclosure. The computer program product may include a computer-readable medium.

[0298]

[0285] By way of example and not limitation, such computer-readable storage media may comprise 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 may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection is properly referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead cover non-transitory tangible storage media. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks typically reproduce data magnetically and discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer readable media.

[0299]

[0286] The instructions may be executed by one or more processors, such as one or more DSPs, general-purpose microprocessors, ASICs, FPGAs, or other equivalent integrated circuits or discrete logic circuits. Thus, the terms "processor" and "processing circuitry" as used herein may refer to any of the above structures, or any other structures suitable for implementing the techniques described herein. Furthermore, in some aspects, the functions described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or may be incorporated into a composite codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

[0300]

[0287] The techniques of the present disclosure may be implemented in a wide variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs) or sets of ICs (e.g., chipsets). In this disclosure, various components, modules, or units have been described to highlight functional aspects of devices configured to implement the disclosed techniques, but the components, modules, or units do not necessarily require realization by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units, including one or more processors described above, along with suitable software and / or firmware.

[0301]

[0288] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. 1. A method for processing video data, comprising the steps of: Receiving a picture; and coding a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture, the plurality of transforms including two or more of a rotation transform that rotates the picture, a mirroring transform that mirrors the picture, or a combination of the rotation transform and the mirroring transform. A method for providing the above.

2. 2. The method of claim 1 , wherein the plurality of transforms includes a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising the 180 degree counterclockwise transformation followed by the horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by the horizontal mirroring transformation, a fifth transform comprising the 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by the horizontal mirroring transformation, and a seventh transform comprising the 270 degree counterclockwise transformation.

3. The method of claim 1 , wherein the transform type syntax element further comprises a value indicating that no transform is applied.

4. 2. The method of claim 1 , wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

5. The coding comprises decoding, the method comprising: applying the transform to the picture in accordance with the transform type syntax element to form a transformed picture; displaying the transformed picture; and The method of claim 1 further comprising:

6. The method of claim 1 , wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

7. The method of claim 1 , wherein the picture-oriented message comprises a picture-oriented open bitstream unit (OBU).

8. 1. An apparatus configured to process video data, comprising: a memory configured to store a picture; and one or more processors implemented in circuitry and in communication with the memory, the one or more processors comprising: receiving the picture; and coding a picture orientation message including a transform type syntax element, where the transform type syntax element indicates a transform of a plurality of transforms to be applied to the picture, the plurality of transforms including two or more of a rotation transform that rotates the picture, a mirroring transform that mirrors the picture, or a combination of the rotation transform and the mirroring transform.

23. An apparatus configured to:

9. 9. The apparatus of claim 8, wherein the plurality of transforms includes a first transform comprising a horizontal mirroring transformation, a second transform comprising a 180 degree counterclockwise rotation transformation, a third transform comprising the 180 degree counterclockwise transformation followed by the horizontal mirroring transformation, a fourth transform comprising a 90 degree counterclockwise transformation followed by the horizontal mirroring transformation, a fifth transform comprising the 90 degree counterclockwise transformation, a sixth transform comprising a 270 degree counterclockwise transformation followed by the horizontal mirroring transformation, and a seventh transform comprising the 270 degree counterclockwise transformation.

10. The apparatus of claim 8 , wherein the transform type syntax element further comprises a value indicating that no transform is applied.

11. 10. The apparatus of claim 8, wherein the picture orientation message further includes a cancel flag and a persistence flag, the cancel flag indicating whether a previous persistence flag is canceled and the persistence flag indicating whether the picture orientation message applies to a subsequent picture.

12. The apparatus is configured to decode the picture orientation message, the one or more processors: applying the transform to the picture in accordance with the transform type syntax element to form a transformed picture; displaying the transformed picture; and The apparatus of claim 8 , further configured to:

13. The apparatus of claim 8 , wherein the picture orientation message comprises a picture orientation supplemental enhancement information (SEI) message.

14. The apparatus of claim 8 , wherein the picture-oriented message comprises a picture-oriented open bitstream unit (OBU).

15. 8. A non-transitory computer readable storage medium storing instructions that, when executed, cause one or more processors of a device configured to process video data to perform the method of any one of claims 1 to 7.

Images