CN116848845A

CN116848845A - Picture orientation and quality metric supplemental enhancement information message for video coding

Info

Publication number: CN116848845A
Application number: CN202280014796.9A
Authority: CN
Inventors: Y·何; M·Z·科班; D·鲁萨诺夫斯基
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2021-04-02
Filing date: 2022-03-09
Publication date: 2023-10-03

Abstract

The video encoder and video decoder are configured as Supplemental Enhancement Information (SEI) messages. The SEI message may include a picture orientation transform type syntax element that indicates how the picture may be rotated and/or mirrored. The SEI message may also include a quality metric.

Description

Picture orientation and quality metric supplemental enhancement information message for video coding

The present application requires enjoyment of priority from the following applications: U.S. patent application Ser. No. 17/653,945, filed on 3/8 of 2022; and U.S. provisional application serial No. 63/170,267 filed on month 4 and 2 of 2021; and U.S. provisional application serial No. 63/214,378 filed on 24 th month 6 of 2021; the entire contents of each of the above applications are incorporated herein by reference. U.S. patent application Ser. No. 17/653,945, filed on 3/8 of 2022, claims the benefit of the following applications: U.S. provisional application No. 63/170,267, filed on 2/4 at 2021; and U.S. provisional application serial No. 63/214,378 filed on 24 th month 6 of 2021.

Technical Field

The present disclosure relates to video encoding and video decoding.

Background

Digital video capabilities can be incorporated into a wide range of devices including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal Digital Assistants (PDAs), laptop or desktop computers, tablet computers, electronic book readers, digital cameras, digital recording devices, digital media players, video gaming devices, cellular or satellite radio telephones, so-called "smartphones", video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video coding (coding) techniques such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T h.263, ITU-T h.264/MPEG-4 (section 10, advanced Video Coding (AVC)), ITU-T h.265/High Efficiency Video Coding (HEVC), ITU-T h.266/Versatile Video Coding (VVC), and extensions of such standards, as well as proprietary video codecs/formats such as AOMedia video 1 (AV 1) developed by the open media alliance. By implementing such video coding techniques, a video device may more efficiently transmit, receive, encode, decode, and/or store digital video information.

Video coding techniques include spatial (intra-picture) prediction and/or temporal (inter-picture) prediction to reduce or eliminate redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) may be partitioned into video blocks, which may also be referred to as Coding Tree Units (CTUs), coding Units (CUs), and/or coding nodes. Video blocks in a slice of an intra coded (I) picture are encoded using spatial prediction relative to reference samples in neighboring blocks in the same picture. Video blocks in a slice of an inter-coded (P or B) 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.

Disclosure of Invention

In general, this disclosure describes techniques for coding video data. In particular, the present disclosure describes techniques for encoding and decoding messages (e.g., supplemental Enhancement Information (SEI) messages and/or other packetized structures) that include metadata that assists in processing (e.g., decoding, displaying, etc.) video data. The messages of the present disclosure may include syntax elements that indicate the orientation of the picture and/or a transform to be applied to the decoded picture that may be used to rotate and/or mirror the decoded picture to a desired orientation. The syntax element may indicate a transformation of the entire picture or constituent pictures (e.g., left and right view stereoscopic pictures) for display. In another example, the message may include a syntax element indicating a picture quality metric. The picture quality metric may indicate the coding quality of the picture, such as quality-based viewport switching and quality-based metric measurement.

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

In one example, the present disclosure describes a method of processing video data, the method 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 to be applied to a picture from among a plurality of transforms.

In another example, the present disclosure describes an apparatus configured to process video data, the apparatus comprising: a memory configured to store pictures; and one or more processors implemented in the circuitry and in communication with the memory, the one or more processors configured to: receiving a picture; and coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform to be applied to a picture from among a plurality of transforms.

In another example, the present disclosure describes an apparatus configured to process video data, the apparatus comprising: a unit 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 from among a plurality of transforms to be applied to a picture.

In another example, the 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: receiving a picture; and coding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform to be applied to a picture from among a plurality of transforms.

In another example, the present disclosure describes a method of processing video data, the method comprising: receiving a picture; and decoding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

In another example, the present disclosure describes an apparatus configured to process video data, the apparatus comprising: a memory configured to store pictures; and one or more processors implemented in the circuitry and in communication with the memory, the one or more processors configured to: receiving a picture; and decoding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

In another example, the present disclosure describes an apparatus configured to process video data, the apparatus comprising: a unit for receiving a picture; and means for coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

In another example, the 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: receiving a picture; and decoding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

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

Drawings

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

Fig. 2 is a conceptual diagram illustrating an example rotation of a picture.

Fig. 3 is a conceptual diagram illustrating an example transformation type.

Fig. 4 is a flow chart illustrating an example process for decoding a picture orientation supplemental enhancement information message.

Fig. 5 is a flow chart illustrating an example process for decoding a quality metric supplemental enhancement information message.

Fig. 6 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.

Fig. 7 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.

Fig. 8 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure.

Fig. 9 is a flowchart illustrating an example method for decoding a current block in accordance with the techniques of this disclosure.

Detailed Description

The present disclosure describes techniques for encoding and decoding messages (e.g., supplemental Enhancement Information (SEI) messages and/or other packetized structures) that include metadata that assists in processing (e.g., decoding, displaying, etc.) video data. The messages of the present disclosure may include syntax elements that indicate the orientation of the picture and/or a transform to be applied to the decoded picture that may be used to rotate and/or mirror the decoded picture to a desired orientation. The syntax element may indicate a transformation of the entire picture or constituent pictures (e.g., left and right view stereoscopic pictures) for display. In another example, the message may include a syntax element indicating a picture quality metric. The picture quality metric may indicate the coding quality of the picture, such as quality-based viewport switching and quality-based metric measurement.

Fig. 1 is a block diagram illustrating an example video encoding and decoding system 100 that may perform the techniques of this disclosure. In general, the techniques of this disclosure are directed to coding (encoding and/or decoding) video data. Generally, video data includes any data used to process video. Thus, video data may include original unencoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata (such as signaling data).

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

In the example of fig. 1, source device 102 includes video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes input interface 122, video decoder 300, memory 120, and display device 118. In accordance with the present disclosure, the video encoder 200 of the source device 102 and the video decoder 300 of the destination device 116 may be configured to apply techniques for SEI message decoding. 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 the destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source, such as an external camera. Likewise, the destination device 116 may interface with an external display device instead of including an integrated display device.

The system 100 as shown in fig. 1 is only one example. In general, any digital video encoding and/or decoding device may perform techniques for SEI message coding. Source device 102 and destination device 116 are merely examples of such transcoding devices in which source device 102 generates transcoded video data for transmission to destination device 116. The present disclosure refers to a "transcoding" device as a device that performs transcoding (e.g., encoding and/or decoding) of data. Accordingly, the video encoder 200 and the video decoder 300 represent examples of a decoding apparatus (specifically, a video encoder and a video decoder), respectively. In some examples, source device 102 and destination device 116 may operate in a substantially symmetrical manner such that each of source device 102 and destination device 116 includes video encoding and decoding components. Thus, the system 100 may support unidirectional or bidirectional video transmission between the source device 102 and the destination device 116, for example, for video streaming, video playback, video broadcasting, or video telephony.

In general, video source 104 represents a source of video data (i.e., original, unencoded video data) and provides a series of consecutive pictures (also referred to as "frames") of video data to video encoder 200, video encoder 200 encoding the data for the pictures. The video source 104 of the 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 the source video, or a combination of real-time video, archived video, and computer-generated video. In each case, the video encoder 200 may encode captured, pre-captured, or computer-generated video data. Video encoder 200 may rearrange pictures from the received order (sometimes referred to as the "display order") to a coding order for coding. The video encoder 200 may generate a bitstream including the encoded video data. The source device 102 may then output the encoded video data via the output interface 108 onto the computer-readable medium 110 for receipt and/or retrieval by an input interface 122, such as the destination device 116.

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

Computer-readable medium 110 may represent any type of medium or device capable of transmitting encoded video data from source device 102 to destination device 116. In one example, the computer-readable medium 110 represents a communication medium that enables the source device 102 to send encoded video data directly to the destination device 116 in real-time, e.g., via a radio frequency network or a computer-based network. According to a communication standard, such as a wireless communication protocol, output interface 108 may modulate a transmission signal including encoded video data, and input interface 122 may demodulate a received transmission signal. The communication medium may include any wireless or wired communication medium such as a Radio Frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network such as: a local area network, a wide area network, or a global network such as the internet. The communication medium may include routers, switches, base stations, or any other device that may facilitate communication from source device 102 to destination device 116.

In some examples, source device 102 may output encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access 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 hard drives, blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or any other suitable digital storage media for storing encoded video data.

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

File server 114 may be any type of server device capable of storing encoded video data and transmitting the encoded video data to destination device 116. File server 114 may represent a web server (e.g., for a website), a server configured to provide file transfer protocol services such as File Transfer Protocol (FTP) or file delivery over unidirectional transport (FLUTE) protocol, content Delivery Network (CDN) devices, hypertext transfer protocol (HTTP) servers, multimedia Broadcast Multicast Service (MBMS) or enhanced MBMS (eMBMS) servers, and/or Network Attached Storage (NAS) devices. File server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as dynamic adaptive streaming over HTTP (DASH), real-time streaming over HTTP (HLS), real-time streaming protocol (RTSP), dynamic streaming over HTTP, and the like.

The destination device 116 may access the encoded video data from the file server 114 via any standard data connection, including an internet connection. This may include a wireless channel (e.g., wi-Fi connection), a wired connection (e.g., digital Subscriber Line (DSL), cable modem, etc.), or a combination of both suitable for accessing encoded video data stored on file server 114. The input interface 122 may be configured to operate according to any one or more of the following: various protocols discussed above for retrieving or receiving media data from file server 114, or other such protocols for retrieving media data.

Output interface 108 and 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 a variety of IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 comprise wireless components, output interface 108 and input interface 122 may be configured to transmit data (such as encoded video data) according to a cellular communication standard, such as 4G, 4G-LTE (long term evolution), LTE-advanced, 5G, etc. In some examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 may be configured to communicate in accordance with other wireless standards (such as the IEEE 802.11 specification, the IEEE 802.15 specification (e.g., zigBee ^TM ) Bluetooth (R) ^TM Standard, etc.) to transmit data (such as encoded video data). In some examples, source device 102 and/or destination device 116 may include respective system-on-chip (SoC) devices. For example, source device 102 may include a SoC device to perform functions attributed to video encoder 200 and/or output interface 108, and destination device 116 may include a SoC device to perform functions attributed to video decoder 300 and/or input interface 122.

The techniques of this disclosure may be applied to video coding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, internet streaming video transmission (such as dynamic adaptive streaming over HTTP (DASH)), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications.

The input interface 122 of the destination device 116 receives the encoded video bitstream from the computer readable medium 110 (e.g., communication medium, storage device 112, file server 114, etc.). The encoded video bitstream may include signaling information (which is also used by the video decoder 300) defined by the video encoder 200 such as the following syntax elements: the syntax element has values that describe characteristics and/or processing of the video block or other coding unit (e.g., slice, picture, group of pictures, sequence, etc.). The display device 118 displays the decoded pictures of the decoded video data to the user. 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.

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 process multiplexed streams including both audio and video in a common data stream.

Video encoder 200 and video decoder 300 may each be implemented as any of a variety of suitable encoder and/or decoder circuits, such as one or more microprocessors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs), discrete logic, software, hardware, firmware, or any combinations thereof. When the techniques are implemented in part in software, a device may store instructions for the software in a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the 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. Devices including video encoder 200 and/or video decoder 300 may include integrated circuits, microprocessors, and/or wireless communication devices (such as cellular telephones).

Video encoder 200 and video decoder 300 may operate in accordance with a video coding standard, such as ITU-T h.265 (also known as High Efficiency Video Coding (HEVC)) or an extension thereto, such as a multiview and/or scalable video coding extension. Alternatively, the video encoder 200 and video decoder 300 may operate in accordance with other proprietary or industry standards, such as the ITU-T h.266 standard, also known as universal video coding (VVC). In other examples, video encoder 200 and video decoder 300 may operate in accordance with proprietary video codecs/formats, such as AOMedia video 1 (AV 1), extensions of AV1, and/or subsequent versions of AV1 (e.g., AV 2). In other examples, video encoder 200 and video decoder 300 may operate in accordance with 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 perform the techniques of this disclosure in connection with any video coding technique that uses SEI messages to determine picture orientation and/or picture quality metrics.

In general, video encoder 200 and 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 comprise a two-dimensional matrix of samples of luminance and/or chrominance data. In general, video encoder 200 and video decoder 300 may decode video data represented in YUV (e.g., Y, cb, cr) format. That is, the video encoder 200 and the video decoder 300 may code a luminance component and a chrominance component, instead of red, green, and blue (RGB) data for samples of a picture, wherein the chrominance component may include both a red-hue chrominance component and a blue-hue chrominance component. In some examples, video encoder 200 converts the received RGB formatted data to a YUV representation before encoding, and video decoder 300 converts the YUV representation to RGB format. Alternatively, a preprocessing and post-processing unit (not shown) may perform these conversions.

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

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 zero or four child nodes. A node without child nodes may be referred to as 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 the PU and the TU. For example, in HEVC, a Residual Quadtree (RQT) represents a partition of TUs. In HEVC, PUs represent inter prediction data, while TUs represent residual data. The intra-predicted CU includes intra-prediction information, such as an intra-mode indication.

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 video encoder 200, partitions a picture into a plurality of Coding Tree Units (CTUs). The video encoder 200 may partition the CTUs according to a tree structure, such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure. QTBT structures remove the concept of multiple partition types, such as partitioning between CUs, PUs, and TUs of HEVC. The QTBT structure includes two levels: a first level partitioned according to a quadtree partitioning, and a second level partitioned according to a binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. Leaf nodes of the binary tree correspond to Coding Units (CUs).

In the MTT partitioning structure, blocks may be partitioned using a Quadtree (QT) partition, a Binary Tree (BT) partition, and one or more types of Trigeminal Tree (TT) (also referred to as Ternary Tree (TT)) partitions. A trigeminal or ternary tree partition is a partition in which a block is divided into three sub-blocks. In some examples, the trigeminal or ternary tree partitioning divides a block into three sub-blocks, rather than centrally dividing the original block. The segmentation types (e.g., QT, BT, and TT) in MTT may be symmetrical or asymmetrical.

When operating according to the AV1 codec, the video encoder 200 and the video decoder 300 may be configured to code video data in blocks. In AV1, the largest decoding block that can be processed is called a super block. In AV1, a superblock may be 128x128 luma samples or 64x64 luma samples. However, in a subsequent video coding format (e.g., AV 2), the super block may be defined by a different (e.g., larger) luma sample size. In some examples, the superblock is the top level of the block quadtree. Video encoder 200 may further partition the super block into smaller coding blocks. The video encoder 200 may use square or non-square partitioning to partition super blocks and other coding blocks into smaller blocks. Non-square blocks may include N/2xN, nxN/2, N/4xN, and NxN/4 blocks. Video encoder 200 and video decoder 300 may perform separate prediction and transform processes for each of the coding blocks.

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

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

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

In some examples, the CTU includes a Coding Tree Block (CTB) of luma samples of a picture having three sample arrays, two corresponding CTBs of chroma samples, or CTBs of samples of a monochrome picture or a picture coded using three separate color planes, and a syntax structure for coding the samples. CTBs may be blocks of NxN samples for some value of N such that dividing a component into CTBs is a partition. The component is an array or a single sample from one of three arrays (luminance and two chromaticities) that constitute a picture in a 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of the array that constitutes a picture in a monochrome format. In some examples, the coding block is a block of MxN samples for some values of M and N such that dividing CTBs into coding blocks is a partition.

Blocks (e.g., CTUs or CUs) may be grouped in pictures in various ways. As one example, a brick-type region (brick) may refer to a rectangular region of CTU rows within a particular tile in a picture. A tile may be a rectangular region of CTUs within 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 a picture and a width specified by a syntax element (e.g., such as in a picture parameter set). A tile row refers to a rectangular region of a CTU having a height specified by a syntax element (e.g., such as in a picture parameter set) and a width equal to the width of a picture.

In some examples, a tile may be divided into a plurality of tile-shaped regions, each of which may include one or more rows of CTUs within the tile. Tiles that are not divided into multiple tile-shaped regions may also be referred to as tile-shaped regions. However, the brick-shaped region that is a true subset of tiles may not be referred to as a tile. The tile-shaped regions in the picture may also be arranged in slices. A slice may be an integer number of brick-type regions of a picture, which may be uniquely contained in a single Network Abstraction Layer (NAL) unit. In some examples, the slice includes a number of complete tiles or a contiguous sequence of complete tile-shaped regions of only one tile.

The present disclosure may interchangeably use "NxN" and "N by N" to refer to the sample size of a block (such as a CU or other video block) in both the vertical and horizontal dimensions, e.g., 16x16 samples or 16 by 16 samples. Typically, a 16x16CU will have 16 samples in the vertical direction (y=16) and 16 samples in the horizontal direction (x=16). Likewise, an NxN CU typically has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. Samples in a CU may be arranged in rows and columns. Furthermore, a CU does not necessarily need to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include NxM samples, where M is not necessarily equal to N.

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

To predict a CU, video encoder 200 may typically form a prediction block for the CU by 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 prediction block using one or more motion vectors. Video encoder 200 may typically perform a motion search to identify reference blocks that closely match the CU, e.g., in terms of differences between the CU and the reference blocks. The video encoder 200 may calculate a difference metric using a Sum of Absolute Differences (SAD), a Sum of Squared Differences (SSD), a Mean Absolute Difference (MAD), a Mean Squared Difference (MSD), or other such difference calculation to determine whether the reference block closely matches the current CU. In some examples, video encoder 200 may use unidirectional prediction or bi-directional prediction to predict the current CU.

Some examples of VVCs also provide affine motion compensation modes, which may be considered inter prediction modes. In affine motion compensation mode, the video encoder 200 may determine two or more motion vectors representing non-translational motion (such as zoom-in or zoom-out, rotation, perspective motion, or other irregular types of motion).

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

The video encoder 200 encodes data representing a prediction mode for the current block. For example, for inter prediction modes, the video encoder 200 may encode data representing which of the various available inter prediction modes is used, as well as motion information for the corresponding mode. For unidirectional or bi-directional inter prediction, for example, the video encoder 200 may use Advanced Motion Vector Prediction (AMVP) or merge mode to encode the motion vectors. The video encoder 200 may use a similar mode to encode the motion vectors for the affine motion compensation mode.

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

After prediction, such as intra prediction or inter prediction, for a block, video encoder 200 may calculate residual data for the block. Residual data, such as a residual block, represents a sample-by-sample difference between a block and a prediction block for the block, the prediction block being 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 the transform domain instead of in the sample domain. For example, video encoder 200 may apply a Discrete Cosine Transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. In addition, the video encoder 200 may apply a secondary transform, such as a mode dependent inseparable secondary transform (MDNSST), a signal dependent transform, a Karhunen-Loeve transform (KLT), etc., after the first transform. The video encoder 200 generates transform coefficients after applying one or more transforms.

As described above, after any transform used to generate transform coefficients, video encoder 200 may perform quantization of the transform coefficients. Quantization generally refers to the process of: in this process, the transform coefficients are quantized to potentially reduce the amount of data representing the transform coefficients, thereby providing further compression. By performing the quantization process, the video encoder 200 may reduce the bit depth associated with some or all of the transform coefficients. For example, the video encoder 200 may round n-bit values down to m-bit values during quantization, where n is greater than m. In some examples, to perform quantization, video encoder 200 may perform a bitwise right shift of the value to be quantized.

After quantization, the video encoder 200 may scan the transform coefficients, thereby generating a one-dimensional vector from a two-dimensional matrix comprising quantized transform coefficients. The scan may be designed to place higher energy (and thus lower frequency) transform coefficients in front of the vector and lower energy (and thus higher frequency) transform coefficients in back of the vector. In some examples, video encoder 200 may scan the quantized transform coefficients using a predefined scan order to produce a serialized vector and then entropy encode the quantized transform coefficients of the vector. In other examples, video encoder 200 may perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 may entropy encode the one-dimensional vector, e.g., according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy encode values of syntax elements that describe metadata associated with the encoded video data for use by the video decoder 300 in decoding the video data.

To perform CABAC, the video encoder 200 may assign contexts within the context model to symbols to be transmitted. The context may relate to, for example, whether the adjacent value of the symbol is a zero value. The probability determination may be based on the context assigned to the symbol.

Video encoder 200 may also generate syntax data (such as block-based syntax data, picture-based syntax data, and sequence-based syntax data), or other syntax data (such as Sequence Parameter Sets (SPS), picture Parameter Sets (PPS), or Video Parameter Sets (VPS)) to video decoder 300, for example, in a picture header, a block header, a slice header. Likewise, video decoder 300 may decode such syntax data to determine how to decode the corresponding video data.

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

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

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

In general, the present disclosure may relate to "signaling" certain information (such as syntax elements). The term "signaling" may generally refer to the transmission of values for syntax elements and/or other data for decoding encoded video data. That is, the video encoder 200 may signal values for syntax elements in the bitstream. In general, signaling refers to generating values in a bit stream. As described above, the source device 102 may stream the bits to the destination device 116 in substantially real-time or non-real-time (such as may occur when storing syntax elements to the storage device 112 for later retrieval by the destination device 116).

In general, this disclosure describes techniques for coding video data. In particular, this disclosure describes techniques for decoding SEI messages. The SEI message of the present disclosure may include a syntax element indicating the orientation of the picture. 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.

The common supplemental enhancement information (VSEI) standard (e.g., ITU-T h.274 and ISO/IEC 23002-7) specifies video availability information (VUI) messages and some of the SEI messages used with VVC bitstreams. The SEI message enables the video encoder 200 to include metadata in the bitstream that is not necessary for proper decoding of sample values of the output pictures, but may be used for various other purposes. Video encoder 200 may be configured to include any number of SEI Network Abstraction Layer (NAL) units in the access unit, and each SEI NAL unit may include one or more SEI messages. The specification and system using VVC may specify an encoder to generate a particular SEI message, or may define a particular process for a particular type of received SEI message.

The following document specifies a display orientation SEI message to inform a decoder (e.g., video decoder 300) of a transform recommended to be applied to a cropped decoded picture prior to display: ISO/IEC JTC 1/SC 29/WG 11N 18277, "Information technology-High efficiency coding and media delivery in heterogeneous environments-Part 2:High Efficiency Video Coding",2019 ("HEVC"). The syntax structure of the display orientation SEI message of HEVC is shown in table 1 below.

Table 1 shows azimuth SEI message syntax

As can be seen in table 1, the display orientation SEI message of HEVC allows for the indication of horizontal flip (hor_flip), vertical flip (ver_flip), and counterclockwise rotation (anti-rotation) transforms.

The 3GPP specifies Coordination of Video Orientation (CVO) in the following documents: technical Specification (TS) 26.114, "IP Multimedia Subsystem (IMS); multimedia telephony; media handling and interaction ",2021. The CVO signals the current position of the image captured at the sender side (e.g., at the source device 102) to the receiver (e.g., destination device 116) for appropriate rendering and display. CVO information for lower rotation granularity is carried in bytes in the following format to support horizontal flip and 90 degree rotation:

LSB represents the least significant bit.

CVO information for higher rotation granularity is carried in bytes in the following format:

some current examples of the VSEI standard do not support any azimuth metadata. HEVC display orientation SEI messages do not take into account frame packing situations, where rotation should be applied to each constituent picture rather than the entire picture. Fig. 2 shows an example of display rotation of frame-packed pictures, where each constituent picture should be rotated separately. As shown in fig. 2, the picture 150 includes two constituent pictures (e.g., a left view picture and a right view picture for stereoscopic video). Using the techniques of this disclosure, video encoder 200 may send a code and SEI message that includes a transform type syntax element that directs video decoder 300 to perform a rotational transform on each of the constituent pictures to implement transformed picture 152.

The example VSEI per-region packing (RWP) SEI message provides information enabling remapping of color samples of cropped decoded pictures onto projected pictures. However, when an omni-directional video projection is indicated to be applied to a picture, RWP SEI messages are used. There should be no RWP SEI message with RWP _cancel_flag equal to 0 in Coding Layer Video Sequences (CLVS) applicable to pictures.

Picture quality metrics for evaluationPicture quality and coding performance. The following documents specify the carrying of timing metadata metrics of media such as peak signal-to-noise ratio (PSNR), structural Similarity Index Metric (SSIM), video Quality Metric (VQM), and Mean Opinion Score (MOS) in ISOBMFF (ISO/IEC basic media file format): ISO/IEC 23001-10, "Information technology-MPEG systems technologies-Part 10:Carriage of Timed Metadata Metrics of Media in ISO Base Media File Format",2015. Picture quality-related ordering is also specified in the following documents to facilitate quality-related viewport switching and immersive media metrics: OMAF, ISO/IEC JTC1/SC29/WG11N19042, "Text of ISO/IEC DIS23090-2 2 ^nd edition OMAF ",2020; immersive Media Metrics (IMM), ISO/IEC JTC1/SC29/WG3N0073, "IS of ISO/IEC 23090-6Immersive Media Metrics," 2020. Some picture quality metrics (such as PSNR and SSIM) may be obtained only on the encoder side. SEI messages carrying such information can provide relevant information to system applications.

Picture orientation SEI message

According to one example of the present disclosure, video encoder 200 is configured to generate and signal a picture orientation SEI message that includes 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., par transform type), wherein the transform type syntax element indicates a transform from among a plurality of transforms to be applied to a 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 syntax elements contained 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.

Table 2 picture orientation SEI message syntax

In general, a Picture Orientation (POR) SEI message provides information for informing the video decoder 300 of the transformations recommended to be applied to the decoded picture prior to display. In some examples, the decoded picture may be a cropped picture.

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 output order. A value of the syntax element por_cancel_flag equal to 0 indicates that POR information follows.

The value of the syntax element por_persistence_flag specifies the persistence of the POR SEI message for the current layer.

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

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

-new CLV start of current layer.

-end of bit stream.

-outputting a picture in the current layer in an Access Unit (AU) associated with the POR SEI message, which follows the current picture in output order.

The syntax element por_structure_picture_mapping_flag having a value equal to 1 specifies that the SEI message is individually applicable to each constituent picture, and the stereoscopic frame packing format is indicated by a frame packing arrangement SEI message. The syntax element pore_component_picture_mapping_flag having a value equal to 0 specifies that the SEI message is applicable to a cropped decoded picture.

The value of the syntax element pore_structure_picture_mapping_flag should be equal to 0 when any of the following conditions is true:

StereoFlag is equal to 0.

StereoFlag is equal to 1 and fp_arrangement_type is equal to 5.

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

A value of fp_arrangement_type equal to 5 indicates that the component planes of the clipped decoded picture output in output order form a time interlace of alternating first and second component frames.

The value of the syntax element pore_transform_type specifies the transform (e.g., rotation, mirror, or a combination of rotation and mirror) that can be applied to the picture. Note that in some examples, mirroring may be referred to as flipping. When the transform indicated by the por transform type specifies both rotation and mirroring, the video decoder 300 may be configured to apply the rotation transform before applying the mirroring, or vice versa. Example values for the pore_transform_type are specified in table 3 below. In one example, the value of pore_transform_type from 8 to 31 is reserved for future use by ITU-T|ISO/IEC.

Table 3pore_transform_type value

Value of	Description of the invention
		0	No conversion
1	Horizontal mirroring
		2	Rotated 180 degrees (anticlockwise)
3	Rotated 180 degrees (inverted)Hour hand
		4	Rotated 90 degrees (counterclockwise) before horizontal mirroring
5	Rotated 90 degrees (anticlockwise)
		6	Rotated 270 degrees (counterclockwise) before horizontal mirroring
7	Rotation 270 degree (anticlockwise)
		8..31	Reservation

The specific values of table 3 are only one example. In other examples, more or fewer transform types may be specified. Further, the transformations may be specified in a different order than that shown in table 3.

Fig. 3 is a conceptual diagram illustrating an example transformation type. In the example of table 3, when the transform syntax element has a value of 0, the video decoder 300 may not apply the transform. Fig. 3 shows an original picture 160 for which no transformation is applied. Other transform types in fig. 3 will be shown with reference to original picture 160. When the transform syntax element has a value of 1, the video decoder 300 may apply a horizontal mirror transform to the original picture 160 to obtain the 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 counter-clockwise rotation transform to the original picture 160 to obtain the picture 164. When the transform syntax element has a value of 3, the video decoder 300 may apply a 180 degree counter-clockwise rotation transform to the original picture 160, followed by a horizontal mirror transform, to obtain the picture 166.

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

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

In one example of the present disclosure, source device 102 may be configured to receive a picture (400). Source device 102 may also be configured to encode the pictures (e.g., using video encoder 200) and transmit the encoded video bitstream to destination device 116. The source device 102 may also be configured to determine a recommended transformation type for the picture (402). The recommended transform type may be a transform type from among a plurality of transform types. The source device 102 may also be configured to encode a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform to be applied to the picture from among a plurality of transforms (404).

The destination device 116 may be configured to receive a picture (410). Destination device 116 may also be configured to decode the picture (e.g., using video decoder 300). The destination device 116 may also decode a picture orientation message that includes a transform type syntax element that indicates a transform from among a plurality of transforms to be applied to the picture (412). The destination device 116 may also be configured to apply a transform to the picture according to the transform type syntax element to form a transformed picture (414), and display the transformed picture (416).

In one example of the present disclosure, the picture orientation message includes a picture orientation SEI message. In another example, the picture orientation message includes a picture orientation Open Bitstream Unit (OBU).

As described above, the plurality of transforms includes two or more of a rotation transform, a mirror transform, or a combination of rotation and mirror transforms. In a more specific example, the plurality of transforms includes: a first transform comprising a horizontal mirror transform; a second transformation comprising a 180 degree counter-clockwise rotation transformation; a third transformation comprising a 180 degree counterclockwise transformation and a subsequent horizontal mirrored transformation; a fourth transformation comprising a 90 degree counterclockwise transformation and a subsequent horizontal mirrored transformation; a fifth transform comprising a 90 degree counterclockwise transform; a sixth transformation comprising a 270 degree counterclockwise transformation and a subsequent horizontal mirrored transformation; and a seventh transform comprising a 270 degree counterclockwise transform. In further examples, the transform type syntax element further includes a value indicating that no transform is to be applied.

In some examples, video encoder 200 may signal a high granularity rotation in an SEI message. High granularity rotation and mirroring may be applied to each constituent picture. In general, a high granularity of rotation may indicate the degree of rotation at relatively small intervals. For example, a high granularity rotation may include rotating the picture at an angle less than 90 degrees. Where each constituent picture may be rotated differently, video encoder 200 may specify a separate azimuth transformation type or high granularity rotation in an SEI message or other metadata type, each applied to one constituent picture.

In some examples, video encoder 200 may specify a constituent picture match flag in CVO signaling. The constituent picture matching flag may indicate a rotation granularity applied to each constituent picture.

Image quality metric SEI message

According to another example of the present disclosure, video encoder 200 is configured to generate and signal picture quality metric messages (e.g., SEI messages and/or other packetized structures) including one or more of the syntax elements shown in table 4 below. The video decoder 300 is configured to receive the picture quality metric SEI message and may process and/or display the picture according to syntax elements contained therein. For example, destination device 116 and/or video decoder 300 may be configured to apply one or more post-processing techniques to the decoded picture according to the quality metrics indicated in the picture quality metrics SEI message. Example post-processing techniques may include amplifying the decoded picture based on picture quality. In other examples, video decoder 300 may be configured to use quality metrics to select certain pictures for 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.

Table 4 is an example picture quality metric SEI message. The picture quality metric SEI message provides a quality metric for each color component of the currently decoded picture.

Table 4 picture quality metric SEI message syntax

The value of syntax element pqm _metric_type indicates the type of quality metric associated with the component specified in table 5. The value of pqm _metric_type from 4 to 127 is reserved for future use by ITU-t|iso/IEC and should not be present in the payload data of this version that complies with the present specification.

Table 5 explanation of pqm _Metric_type

pqm_metric_type	Metrics (MEM)
		0	PSNR
1	SSIM
		2	MS-SSIM
3	VQM

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

The syntax element pqm _single_component_flag having a value equal to 1 specifies that the picture associated with the picture quality metric SEI message contains a single color component. The syntax element pqm _single_component_flag having a value equal to 0 specifies that the picture associated with the picture quality metric SEI message contains three color components. The value of pqm _single_component_flag should be equal to (chromaformatidc= 0).

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

Psnr= pqm _psnr [ cIdx ]/100; except for psnr=infinity for pqm _psnr [ cIdx ] equal to 0

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

SSIM＝(pqm_ssim[cIdx]–127)/128

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

MS SSIM＝(pqm_msssim[cIdx]–127)/128

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

VQM＝pqm_vqm[cIdx]/50

the picture quality metric SEI message may carry other quality related metrics such as Perceptual Evaluation of Video Quality (PEVQ), mean Opinion Score (MOS), and/or other picture quality metrics.

In some examples, when a picture is associated with a stereoscopic frame packing arrangement SEI message, the picture quality metric SEI message may specify a quality metric for each constituent picture. When a picture is associated with an SEI message that is packed per region frame, the picture quality metric SEI message may specify a quality metric for each region. An additional syntax element may be added to the SEI message to indicate whether a picture quality metric exists for each constituent picture or each region.

In other examples, the picture quality metric SEI message may carry quality metrics of one or more sub-pictures or regions of interest (ROIs) of the picture associated with the SEI message. Syntax elements indicating the number of sub-pictures or ROIs, syntax elements indicating the sub-picture or ROI positions, and/or syntax elements indicating the sub-picture or ROI size may also be specified in the SEI message.

Additional quality metrics, such as weighted PSNR (wPSNR) and weighted to spherical uniform PSNR (WS-PSNR), may be included in the SEI message to indicate the quality of High Dynamic Range (HDR) and 360 video content.

Another example picture metric SEI message format is provided in table 6:

TABLE 6 SEI message syntax for image quality metrics

The above picture metric SEI message provides a quality metric of the currently decoded picture.

The value of syntax element pqm _cnt_minus1 plus 1 specifies the number of luma component quality metrics indicated by the SEI message.

The value of 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.

Table 7 interpretation of pqm _type

pqm_type	Metrics (MEM)
		0	PSNR
1	wPSNR
		2	WS-PSNR
3	PSNR _sequence
		4	wPSNR _sequence
5	WS-PSNR _sequence

PSNR _sequenc 、wPSNR _sequence And WS-PSNR _sequence The quality metric types respectively indicate a plurality of over the sequencePSNR, wPSNR, and WS-PSNR of pictures.

The value of 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, then the stored 16-bit unsigned integer pqm _value is interpreted as a PSNR value (in dB) as shown below (in floating point), except that for a pqm _value value equal to 0, the PSNR is equal to infinity.

Where M is an integer (e.g., 100).

When the value of the syntax element pqm _type is 1, then the stored 16-bit unsigned integer pqm _value is interpreted as a wPSNR value (in dB) as shown below (in floating point), except that wPSNR is equal to infinity for a pqm _value equal to 0.

Where M is an integer (e.g., 100).

When the value of syntax element pqm _type is 2, then the stored 16-bit unsigned integer pqm _value is interpreted as a WS-PSNR value (in dB), as shown below (in floating point), except that for a pqm _value value equal to 0, WS-PSNR is equal to infinity.

Where M is an integer (e.g., 100).

When the value of the syntax element pqm _type is 3, the quality metric indicates the average luminance PSNR of CLVS to which the associated picture belongs. The 16-bit unsigned integer pqm _value is interpreted as the result of a sequence-level PSNR quality metric (in dB) and is derived as follows (in floating point) except that for a pqm _value value equal to 0, PSNR is equal to infinity.

Where M is an integer (e.g，100)。

When the value of the syntax element pqm _type is 4, the quality metric indicates the average luminance weighted PSNR of CLVS to which the associated picture belongs. The 16-bit unsigned integer pqm _value is interpreted as a sequence-level wPSNR value (in dB), as shown below (in floating point), except that wPSNR is equal to infinity for a pqm _value value equal to 0.

Where M is an integer (e.g., 100).

When the value of the syntax element pqm _type is 5, the quality metric indicates the average luminance WS-PSNR of 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), shown below (in floating point), except that WS-PSNR is equal to infinity for a pqm _value equal to 0.

Where M is an integer (e.g., 100).

In another example, an additional quality metric type may be included in the SEI message to indicate an average quality metric applicable to multiple video frames. The 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 in output order for all subsequent pictures of the current layer. The second syntax element may be specified in the SEI message to cancel the persistence of any previous quality metrics in output order.

In another example, when there is an average quality metric (such as sequence level PSNR) for any picture of CLVS, there should be an associated picture quality SEI message for the first picture of CLVS. The average picture metric for all SEI messages that apply to the same CLVS should have the same content.

Fig. 5 is a flow chart illustrating an example process for decoding a quality metric supplemental enhancement information message. Fig. 5 illustrates both the encoding and decoding processes of the present disclosure. As shown in fig. 5, the encoding process may be performed by the source device 102 including the video encoder 200. The decoding process may be performed by the destination device 116, including the video decoder 300.

In one example of the present disclosure, source device 102 may be configured to receive a picture (500). Source device 102 may also be configured to encode the pictures (e.g., using video encoder 200) and transmit the encoded video bitstream to destination device 116. The source device 102 may also be configured to determine a quality metric for the picture (502). Source device 102 may also be configured to encode a quality metric message including a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture (504).

In further examples of the present disclosure, source device 102 may be further configured to encode a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics. In one example, the plurality of types of quality metrics include peak signal-to-noise ratio (PSNR). In another example, the plurality of types of quality metrics include two or more of the following: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or 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.

The destination device 116 may be configured to receive a picture (510). Destination device 116 may also be configured to decode the picture (e.g., using video decoder 300). Destination device 116 may also decode a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture (512). The destination device 116 may also be configured to apply post-processing techniques to the picture according to the value of the quality metric to form a processed picture (514), and display the processed picture (516).

In further examples of the present disclosure, destination device 116 may be further configured to decode a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among the plurality of types of quality metrics. In one example, the plurality of types of quality metrics include peak signal-to-noise ratio (PSNR). In another example, the plurality of types of quality metrics include two or more of the following: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or 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.

In one example of the present disclosure, the quality metric message includes a quality metric SEI message. In another example, the quality metric message includes a quality metric open bit stream unit (OBU).

In other examples of the present disclosure, source device 102 and/or destination device 116 may be configured to decode a second quality metric message including a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture or region of interest of the picture.

For purposes of explanation, the above techniques 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 performed by video encoding devices configured to other video coding standards and video coding formats (such as AV1, future versions of AV1, and successor to AV1 video coding formats). For example, these messages may be packetized data, such as open bit stream units (OBUs) including at least some of the metadata described in this disclosure, as opposed to being SEI messages. As one example, some or all of the above-described syntax included within the picture orientation SEI message may be included within the picture orientation OBU such that the picture orientation OBU includes one or more of a cancel flag, a persistence flag, a component picture matching flag, or a transform type syntax element. As another example, some or all of the above-described syntax included within the picture quality metric SEI message may be included within the picture quality metric OBU such that the picture quality metric OBU includes one or more syntax elements indicating a quality metric of the picture.

Fig. 6 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Fig. 6 is provided for purposes of explanation and should not be considered limiting of the techniques as broadly illustrated and described in this disclosure. For purposes of explanation, this disclosure describes a video encoder 200 in accordance with techniques of VVC (ITU-T h.266, being developed) and HEVC (ITU-T h.265). However, the techniques of this disclosure may be performed by video encoding devices configured for other video coding standards and video coding formats (such as AV1 and successor to AV1 video coding formats).

In the example of fig. 6, video encoder 200 includes video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, decoded Picture Buffer (DPB) 218, and entropy encoding unit 220. Any or all of video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, filter unit 216, DPB 218, and entropy encoding unit 220 may be implemented in one or more processors or in processing circuitry. For example, the elements of video encoder 200 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. Further, the video encoder 200 may include additional or alternative processors or processing circuits to perform these functions and others.

Video data memory 230 may store video data to be encoded by components of video encoder 200. Video encoder 200 may receive video data stored in video data store 230 from, for example, video source 104 (fig. 1). DPB 218 may serve as a reference picture memory that stores reference video data for use in predicting subsequent video data by video encoder 200. Video data memory 230 and DPB 218 may be formed from any of a variety of memory devices, such as Dynamic Random Access Memory (DRAM), including Synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. Video data memory 230 and DPB 218 may be provided by the same memory device or separate memory devices. In various examples, video data memory 230 may be on-chip with other components of video encoder 200 (as shown), or off-chip with respect to those components.

In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to video encoder 200 (unless specifically described as such) or memory external to video encoder 200 (unless specifically described as such). In particular, references to video data memory 230 should be understood as reference memory storing video data received by video encoder 200 for encoding (e.g., video data for a current block to be encoded). Memory 106 of fig. 1 may also provide temporary storage of the output from the various units of video encoder 200.

The various elements of fig. 6 are shown to aid in understanding the operations performed by video encoder 200. These units may be implemented as fixed function circuits, programmable circuits or a combination thereof. The fixed function circuit refers to a circuit that provides a specific function and is preset with respect to operations that can be performed. Programmable circuitry refers to circuitry that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For example, the programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by instructions of the software or firmware. Fixed function circuitry may execute software instructions (e.g., to receive parameters or output parameters) but the type of operation that fixed function circuitry performs is typically not variable. In some examples, one or more of these units may be different circuit blocks (fixed function or programmable), and in some examples, one or more of these units may be an integrated circuit.

The video encoder 200 may include an Arithmetic Logic Unit (ALU), a basic functional unit (EFU), digital circuitry, analog circuitry, and/or a programmable core formed from programmable circuitry. In examples where the operations of video encoder 200 are performed using software executed by programmable circuitry, memory 106 (fig. 1) may store instructions (e.g., object code) of the software received and executed by video encoder 200, or another memory (not shown) within video encoder 200 may store such instructions.

The video data memory 230 is configured to store 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.

The mode selection unit 202 comprises a motion estimation unit 222, a motion compensation unit 224 and an intra prediction unit 226. The mode selection unit 202 may include additional functional units that perform video prediction according to other prediction modes. As an example, mode selection unit 202 may include a palette unit, an intra-block copy unit (which may be part of motion estimation unit 222 and/or motion compensation unit 224), an affine unit, a Linear Model (LM) unit, and the like.

The mode selection unit 202 typically coordinates multiple encoding passes (pass) to test combinations of encoding parameters and resulting rate distortion values for such combinations. The coding parameters may include a partition of the CTU into CUs, a prediction mode for the CU, a transform type for residual data of the CU, quantization parameters for residual data of the CU, and the like. The mode selection unit 202 may finally select a combination of coding parameters having better rate-distortion values than other tested combinations.

Video encoder 200 may segment the pictures retrieved from video data store 230 into a series of CTUs and encapsulate one or more CTUs within a slice. The mode selection unit 202 may divide CTUs of pictures 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 dividing CTUs according to a tree structure. Such CUs may also be commonly referred to as "video blocks" or "blocks.

Typically, mode selection unit 202 also controls its components (e.g., motion estimation unit 222, motion compensation unit 224, and intra prediction unit 226) to generate a prediction block for the current block (e.g., the current CU, or the overlapping portion of PU and TU in HEVC). For inter prediction of the current block, motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously coded pictures stored in DPB 218). Specifically, the motion estimation unit 222 may calculate a value representing the degree of similarity of the potential reference block to the current block, for example, from the Sum of Absolute Differences (SAD), the Sum of Squared Differences (SSD), the Mean Absolute Difference (MAD), the Mean Squared Difference (MSD), and the like. The motion estimation unit 222 may typically perform these calculations using sample-by-sample differences between the current block and the reference block being considered. The motion estimation unit 222 may identify the reference block with the lowest value resulting from these calculations, which indicates the reference block that most closely matches the current block.

The motion estimation unit 222 may form one or more Motion Vectors (MVs) defining a position of a reference block in a reference picture relative to a position of a current block in the current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, for unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while for bi-directional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then generate a prediction block using the motion vector. For example, the motion compensation unit 224 may use the motion vector to retrieve the data of the reference block. As another example, if the motion vector has fractional sample precision, the motion compensation unit 224 may interpolate values for the prediction block according to one or more interpolation filters. Furthermore, for bi-directional inter prediction, the motion compensation unit 224 may retrieve data for the two reference blocks identified by the respective motion vectors and combine the retrieved data, e.g. by sample-wise averaging or weighted averaging.

When operating in accordance with the AV1 video coding format, the motion estimation unit 222 and the motion compensation unit 224 may be configured to encode coding blocks (e.g., both luma and chroma coding blocks) of video data using translational motion compensation, affine motion compensation, overlapped Block Motion Compensation (OBMC), and/or composite intra-inter prediction.

As another example, for intra prediction or intra prediction coding, the intra prediction unit 226 may generate a prediction block from samples adjacent to the current block. For example, for directional modes, intra-prediction unit 226 may typically mathematically combine the values of neighboring samples and populate these calculated values in defined directions across the current block to produce a prediction block. As another example, for DC mode, the intra prediction unit 226 may calculate an average of samples adjacent to the current block and generate a prediction block to include the resulting average for each sample of the prediction block.

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

The mode selection unit 202 supplies the prediction block to the residual generation unit 204. The residual generation unit 204 receives the original, unencoded version of the current block from the video data store 230 and the prediction block from the mode selection unit 202. The residual generation unit 204 calculates a sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines a residual block for the current block. In some examples, residual generation unit 204 may also determine differences between sample values in the residual block to generate the residual block using Residual Differential Pulse Code Modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.

In examples where 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. Video encoder 200 and video decoder 300 may support PUs having various sizes. As noted above, the size of a CU may refer to the size of the luma coding block of the CU, while the size of a PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2Nx2N, the video encoder 200 may support PU sizes of 2Nx2N or NxN for intra prediction, and 2Nx2N, 2NxN, nx2N, nxN, or similar symmetric PU sizes for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.

In examples where mode selection unit 202 does not partition the CUs further into PUs, each CU may be associated with a luma coding block and a corresponding chroma coding block. As 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 2Nx2N, 2NxN, or Nx 2N.

For other video coding techniques, such as intra-block copy mode coding, affine mode coding, and Linear Model (LM) mode coding, as some examples, mode selection unit 202 generates a prediction block for the current block being encoded via a respective unit associated with the coding technique. In some examples (such as palette mode coding), mode selection unit 202 may not generate a prediction block, but instead generate a syntax element indicating a manner in which to reconstruct the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy encoding unit 220 to be encoded.

As described above, the residual generation unit 204 receives video data for the current block and the corresponding prediction block. Then, the residual generating unit 204 generates a residual block for the current block. In order to generate the residual block, the residual generation unit 204 calculates a sample-by-sample difference between the prediction block and the current block.

The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "block of transform coefficients"). The transform processing unit 206 may apply various transforms to the residual block to form a block of transform coefficients. For example, transform processing unit 206 may apply a Discrete Cosine Transform (DCT), a direction 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 primary 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.

When operating in accordance with AV1, the 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 "block of transform coefficients"). The transform processing unit 206 may apply various transforms to the residual block to form a block of transform coefficients. For example, transform processing unit 206 may apply a horizontal/vertical transform combination, which may include a Discrete Cosine Transform (DCT), an Asymmetric Discrete Sine Transform (ADST), a flipped ADST (e.g., an inverted order ADST), and an identity transform (IDTX). When an identity transform is used, the transform is skipped in one of the vertical or horizontal directions. In some examples, the transformation process may be skipped.

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

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

The filter unit 216 may perform one or more filter operations on the reconstructed block. For example, the filter unit 216 may perform deblocking operations to reduce blocking artifacts along edges of CUs. In some examples, the operation of the filter unit 216 may be skipped.

When operating in accordance with AV1, the filter unit 216 may perform one or more filter operations on the reconstructed block. For example, the filter unit 216 may perform deblocking operations to reduce blocking artifacts along edges of CUs. In other examples, filter unit 216 may apply a Constrained Direction Enhancement Filter (CDEF), which may be applied after deblocking and may include applying an inseparable nonlinear low pass direction filter based on the estimated edge direction. The filter unit 216 may also include a loop recovery filter that is applied after CDEF and may include a separable symmetric normalized Wiener filter (Wiener filter) or a double self-guiding filter.

Video encoder 200 stores the reconstructed block in DPB 218. For example, in an example where the operation of filter unit 216 is not performed, reconstruction unit 214 may store the reconstructed block to DPB 218. In an example of performing the operation of filter unit 216, filter unit 216 may store the filtered reconstructed block to DPB 218. Motion estimation unit 222 and motion compensation unit 224 may retrieve reference pictures formed from reconstructed (and potentially filtered) blocks from DPB 218 to inter-predict blocks of subsequent encoded pictures. In addition, intra-prediction unit 226 may use the reconstructed block of the current picture in DPB 218 to intra-predict other blocks in the current picture.

In general, entropy encoding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy encoding unit 220 may entropy encode the quantized transform coefficient block from quantization unit 208. As another example, the entropy encoding unit 220 may entropy encode a prediction syntax element (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 that 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 Partitioning Entropy (PIPE) coding operation, an Exponential-Golomb (Exponential-Golomb) coding operation, or another type of entropy coding operation on the data. In some examples, entropy encoding unit 220 may operate in a bypass mode in which syntax elements are not entropy encoded.

The video encoder 200 may output a bitstream that includes entropy encoded syntax elements required to reconstruct blocks of slices or pictures. In particular, the entropy encoding unit 220 may output a bitstream.

According to AV1, the entropy encoding unit 220 may be configured as a symbol-to-symbol adaptive multi-symbol arithmetic decoder. The syntax element in AV1 includes an alphabet of N elements, and the context (e.g., probability model) includes a set of N probabilities. The entropy encoding unit 220 may store the probabilities as an n-bit (e.g., 15-bit) Cumulative Distribution Function (CDF). Entropy encoding unit 22 may perform recursive scaling to update the context using an update factor based on the size of the alphabet.

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

In some examples, operations performed with respect to luma coded blocks need not be repeated for chroma coded blocks. As one example, the operations for identifying Motion Vectors (MVs) and reference pictures for luma coded blocks need not be repeated for identifying MVs and reference pictures for chroma blocks. In particular, MVs for luma coding blocks may be scaled to determine MVs for chroma blocks, and reference pictures may be the same. As another example, the intra prediction process may be the same for both luma and chroma coded blocks.

In accordance with the SEI techniques discussed above, video encoder 200 represents an example of a device configured to encode video data, the device comprising: a memory configured to store video data; and one or more processing units implemented in the circuitry and configured to: receiving a picture; and encoding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform to be applied to the picture from among a plurality of transforms. The video encoder 200 may be further configured to encode a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Fig. 7 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Fig. 7 is provided for purposes of explanation and is not a limitation of the techniques as broadly illustrated and described in this disclosure. For purposes of explanation, this disclosure describes a video decoder 300 in accordance with techniques of VVC (ITU-T h.266, being developed) and HEVC (ITU-T h.265). However, the techniques of this disclosure may be performed by video coding devices configured as other video coding standards.

In the example of fig. 7, video decoder 300 includes Coded Picture Buffer (CPB) memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and Decoded Picture Buffer (DPB) 134. Any or all of CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 134 may be implemented in one or more processors or in processing circuitry. For example, the elements of video decoder 300 may be implemented as one or more circuits or logic elements, as part of a hardware circuit, or as part of a processor, ASIC, or FPGA. Furthermore, the video decoder 300 may include additional or alternative processors or processing circuits to perform these functions and others.

The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. Prediction processing unit 304 may include additional units for performing prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra-block copy unit (which may form part of the motion compensation unit 316), an affine unit, a Linear Model (LM) unit, and the like. In other examples, video decoder 300 may include more, fewer, or different functional components.

When operating in accordance with AV1, the compensation unit 316 may be configured to decode coded blocks of video data (e.g., both luma and chroma coded blocks) using translational motion compensation, affine motion compensation, OBMC, and/or composite inter intra prediction, as described above. Intra-prediction unit 318 may be configured to decode coded blocks of video data (e.g., both luma and chroma coded blocks) using directional intra-prediction, non-directional intra-prediction, recursive filter intra-prediction, CFL, intra-block copy (IBC), and/or palette modes.

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 CPBs that store encoded video data (e.g., syntax elements) from an encoded video bitstream. Further, the CPB memory 320 may store video data other than syntax elements of the coded pictures, such as temporary data representing outputs from various units of the video decoder 300. DPB 314 typically stores decoded pictures, which video decoder 300 may output and/or use as reference video data when decoding subsequent data or pictures of an encoded video bitstream. CPB memory 320 and DPB 314 may be formed of any of a variety of memory devices, such as DRAM (including SDRAM), MRAM, RRAM, or other types of memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip with respect to those components.

Additionally or alternatively, in some examples, video decoder 300 may retrieve coded video data from memory 120 (fig. 1). That is, memory 120 may utilize CPB memory 320 to store data as discussed above. Also, when some or all of the functions of the video decoder 300 are implemented in software to be executed by the processing circuitry of the video decoder 300, the memory 120 may store instructions to be executed by the video decoder 300.

The various units shown in fig. 7 are shown to aid in understanding the operations performed by the video decoder 300. These units may be implemented as fixed function circuits, programmable circuits or a combination thereof. Similar to fig. 6, the fixed function circuit refers to a circuit that provides a specific function and is preset with respect to operations that can be performed. Programmable circuitry refers to circuitry that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For example, the programmable circuit may execute software or firmware that causes the programmable circuit to operate in a manner defined by instructions of the software or firmware. Fixed function circuitry may execute software instructions (e.g., to receive parameters or output parameters) but the type of operation that fixed function circuitry performs is typically not variable. In some examples, one or more of these units may be different circuit blocks (fixed function or programmable), and in some examples, one or more of these units may be an integrated circuit.

The video decoder 300 may include ALUs, EFUs, digital circuits, analog circuits, and/or programmable cores formed from programmable circuits. In examples where the operations of video decoder 300 are performed by software executing on programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software received and executed by video decoder 300.

The entropy decoding unit 302 may receive encoded video data from the CPB and entropy decode the video data to reproduce the syntax element. 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 syntax elements extracted from the bitstream.

Typically, the video decoder 300 reconstructs the pictures on a block-by-block basis. The video decoder 300 may perform a reconstruction operation on each block separately (where the block currently being reconstructed (i.e., decoded) may be referred to as a "current block").

The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of the quantized transform coefficient block and transform information such as Quantization Parameters (QPs) and/or transform mode indications. The inverse quantization unit 306 may determine a quantization degree using a QP associated with the quantized transform coefficient block and, as such, an inverse quantization degree for the inverse quantization unit 306 to apply. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inversely quantize the quantized transform coefficients. The inverse quantization unit 306 may thus form a transform coefficient block including the transform coefficients.

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 rotation transform, an inverse direction transform, or another inverse transform to the transform coefficient block.

Further, the prediction processing unit 304 generates a prediction block from 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 the prediction block. In this case, the prediction information syntax element may indicate a reference picture in DPB 314 from which the reference block is to be retrieved, and a motion vector identifying a position of the reference block in the reference picture relative to a position of the current block in the current picture. Motion compensation unit 316 may generally perform the inter-prediction process in a substantially similar manner as described with respect to motion compensation unit 224 (fig. 6).

As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate the prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, intra-prediction unit 318 may generally perform an intra-prediction process in a substantially similar manner as described with respect to intra-prediction unit 226 (fig. 6). Intra-prediction unit 318 may retrieve data for samples neighboring the current block from DPB 314.

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

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

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

In accordance with the SEI techniques discussed above, video decoder 300 represents an example of a device configured to decode video data, the device comprising: a memory configured to store video data; and one or more processing units implemented in the circuitry and configured to: receiving a picture; and decoding a picture orientation message including a transform type syntax element, wherein the transform type syntax element indicates a transform to be applied to the picture from among a plurality of transforms. The video decoder 300 may be further configured to decode a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Fig. 8 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure. The current block may include the current CU. Although described with respect to video encoder 200 (fig. 1 and 6), it should be understood that other devices may be configured to perform a method similar to the method of fig. 8.

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

Fig. 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 include the current CU. Although described with respect to video decoder 300 (fig. 1 and 7), it should be understood that other devices may be configured to perform a method similar to the method of fig. 9.

The video decoder 300 may receive entropy encoded data for the current block, such as entropy encoded prediction information and entropy encoded data for transform coefficients of a residual block corresponding to the current block (370). The video decoder 300 may entropy decode the entropy encoded data to determine prediction information for the current block and reproduce transform coefficients of the residual block (372). The video decoder 300 may predict the current block (374), for example, using an intra prediction mode or an inter prediction mode as indicated by the prediction information for the current block, to calculate a prediction block for the current block. The video decoder 300 may then inverse scan 376 the regenerated transform coefficients to create blocks of quantized transform coefficients. The video decoder 300 may then inverse quantize the transform coefficients and apply an inverse transform to the transform coefficients to generate a residual block (378). Finally, the video decoder 300 may decode the current block by combining the prediction block and the residual block (380).

Other illustrative aspects of the techniques and apparatus of the present disclosure are described below.

Aspect 1A-a method of processing video data, the method comprising: receiving a picture; and coding a picture orientation Supplemental Enhancement Information (SEI) message, the picture orientation SEI message comprising one or more of: a cancel flag, a persistence flag, a constituent picture match flag, or a transform type syntax element, wherein the transform type syntax element indicates one or more of a rotation or a mirror to be applied to the picture.

Aspect 2A-the method of aspect 1A, wherein coding comprises decoding, and wherein the method further comprises: the picture is processed according to the picture orientation SEI message.

Aspect 3A-the method of aspect 1A or aspect 2A, wherein the picture orientation message comprises a picture orientation Supplemental Enhancement Information (SEI) message.

Aspect 4A-the method of aspect 1A or aspect 2A, wherein the picture orientation message comprises a picture orientation Open Bitstream Unit (OBU).

Aspect 5A-the method of claim 1A, wherein coding comprises encoding.

Aspect 6A-a method of processing video data, the method comprising: receiving a picture; and coding a picture quality metric Supplemental Enhancement Information (SEI) message that includes one or more syntax elements indicating a quality metric of the picture.

Aspect 7A-the method of aspect 6A, wherein coding comprises decoding, and wherein the method further comprises: the picture is processed according to the picture quality metric SEI message.

Aspect 8A-the method of aspect 6A or aspect 7A, wherein the picture orientation message comprises a picture quality metric Supplemental Enhancement Information (SEI) message.

Aspect 9A-the method of any one of aspects 6A-8A, wherein the picture quality metric message includes one or more syntax elements indicating a quality metric of one or more sub-pictures or regions of interest of the picture associated with the picture quality metric message.

Aspect 10A-the method of aspect 9A, wherein the one or more syntax elements indicate a quality metric of High Dynamic Range (HDR) or 360 video content.

Aspect 11A-the method of any of aspects 6A-10A, wherein coding comprises encoding.

Aspect 12A-any combination of the methods according to aspects 1A-10A.

Aspect 13A-an apparatus for processing video data, the apparatus comprising one or more units for performing the method of any of aspects 1A-12A.

Aspect 14A-the device of aspect 13A, wherein the one or more units comprise one or more processors implemented in circuitry.

Aspect 15A-the apparatus of any one of aspects 13A and 14A, further comprising: and a memory for storing the video data.

Aspect 16A-the apparatus of any one of aspects 13A-15A, further comprising: a display configured to display the decoded video data.

The apparatus of aspect 17A-any of aspects 13A-16A, wherein the apparatus comprises one or more of: a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

Aspect 18A-the apparatus of any of aspects 13A-17A, wherein the apparatus comprises a video decoder.

Aspect 19A-the apparatus of any of aspects 13A-18A, wherein the apparatus comprises a video encoder.

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

Aspect 1B-a method of processing video data, the method comprising: receiving a picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 2B-the method of aspect 1B, further comprising: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 3B-the method of aspect 2B, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 4B-the method of aspect 2B, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 5B-the method of aspect 2B, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 6B-the method of aspect 1B, further comprising: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 7B-the method of aspect 1B, further comprising: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 8B-the method of aspect 1B, wherein coding comprises decoding, and wherein the method further comprises: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 9B-the method of aspect 1B, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 10B-the method of aspect 1B, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 11B-an apparatus configured to process video data, the apparatus comprising: a memory configured to store pictures; and one or more processors implemented in the circuitry and in communication with the memory, the one or more processors configured to: receiving the picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 12B-the apparatus of aspect 11B, wherein the one or more processors are further configured to: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 13B-the apparatus of aspect 12B, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 14B-the apparatus of aspect 12B, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 15B-the apparatus of aspect 12B, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 16B-the apparatus of aspect 11B, wherein the one or more processors are further configured to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 17B-the apparatus of aspect 11B, wherein the one or more processors are further configured to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 18B-the apparatus of aspect 11B, wherein the apparatus is configured to decode the quality metric message, and wherein the one or more processors are further configured to: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 19B-the apparatus of aspect 11B, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 20B-the apparatus of aspect 11B, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 21B-an apparatus configured to process video data, the apparatus comprising: a unit for receiving a picture; and means for coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 22B-the apparatus of aspect 21B, further comprising: means for coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a type of quality metric indicated by the quality metric syntax element from among a plurality of types of quality metrics.

Aspect 23B-the apparatus of aspect 22B, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 24B-the apparatus of aspect 22B, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 25B-the apparatus of aspect 22B, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 26B-the apparatus of aspect 21B, further comprising: means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 27B-the apparatus of aspect 21B, further comprising: means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 28B-the apparatus of aspect 21B, wherein the means for coding comprises means for decoding, and wherein the apparatus further comprises: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and means for displaying the processed picture.

Aspect 29B-the apparatus of aspect 21B, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 30B-the apparatus of aspect 21B, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 31B-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: receiving a picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 32B-the non-transitory computer-readable storage medium of aspect 31B, wherein the instructions further cause the one or more processors to: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 33B-the non-transitory computer-readable storage medium of aspect 32B, wherein the plurality of types of quality metrics include peak signal-to-noise ratio (PSNR).

Aspect 34B-the non-transitory computer-readable storage medium of aspect 32, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 35B-the non-transitory computer-readable storage medium of aspect 32B, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 36B-the non-transitory computer-readable storage medium of aspect 31B, wherein the instructions further cause the one or more processors to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 37B-the non-transitory computer-readable storage medium of aspect 31B, wherein the instructions further cause the one or more processors to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 38B-the non-transitory computer-readable storage medium of aspect 31B, wherein the device is configured to decode the quality metric message, and wherein the instructions further cause the one or more processors to: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 39B-the non-transitory computer-readable storage medium of aspect 31B, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 40B-the non-transitory computer-readable storage medium of aspect 31B, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 1C-a method of processing video data, the method comprising: receiving a picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 2C-the method of aspect 1C, further comprising: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 3C-the method of aspect 2C, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 4C-the method of aspect 2C, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 5C-the method of any of aspects 2C-4C, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 6C-the method of any one of aspects 1C-5C, further comprising: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 7C-the method of any one of aspects 1C-5C, further comprising: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 8C-the method of any of aspects 1C-7C, wherein coding comprises decoding, and wherein the method further comprises: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 9C-the method of any of aspects 1C-8C, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 10C-the method of any one of aspects 1C-8C, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 11C-an apparatus configured to process video data, the apparatus comprising: a memory configured to store pictures; and one or more processors implemented in the circuitry and in communication with the memory, the one or more processors configured to: receiving a picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 12C-the apparatus of aspect 11C, wherein the one or more processors are further configured to: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 13C-the apparatus of aspect 12C, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 14C-the apparatus of aspect 12C, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 15C-the apparatus of any one of aspects 12C-14C, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 16C-the apparatus of any of aspects 11C-15C, wherein the one or more processors are further configured to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

The apparatus of any of aspects 17C-11C-15C, wherein the one or more processors are further configured to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

The apparatus of any of aspects 18C-11C-17C, wherein the apparatus is configured to decode the quality metric message, and wherein the one or more processors are further configured to: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 19C-the apparatus of any of aspects 11C-18C, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 20C-the apparatus of any of aspects 11C-18C, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 21C-an apparatus configured to process video data, the apparatus comprising: a unit for receiving a picture; and means for coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 22C-the apparatus of aspect 21C, further comprising: means for coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 23C-the apparatus of aspect 22C, wherein the plurality of types of quality metrics includes peak signal-to-noise ratio (PSNR).

Aspect 24C-the apparatus of aspect 22C, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 25C-the apparatus of any of aspects 22C-24C, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 26C-the apparatus of any one of aspects 21C-25C, further comprising: means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 27C-the apparatus of any one of aspects 21C-25C, further comprising: means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture

The apparatus of any of aspects 28C-21C-27C, wherein the means for coding comprises means for decoding, and wherein the apparatus further comprises: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and means for displaying the processed picture.

Aspect 29C-the apparatus of any of aspects 21C-28C, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 30C-the apparatus of any of aspects 21C-28C, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

Aspect 31C-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: receiving a picture; and coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

Aspect 32C-the non-transitory computer-readable storage medium of aspect 31C, wherein the instructions further cause the one or more processors to: coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

Aspect 33C-the non-transitory computer-readable storage medium of aspect 32C, wherein the plurality of types of quality metrics include peak signal-to-noise ratio (PSNR).

Aspect 34C-the non-transitory computer-readable storage medium of aspect 32, wherein the plurality of types of quality metrics includes two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

Aspect 35C-the non-transitory computer-readable storage medium of any one of aspects 32C-34C, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

Aspect 36C-the non-transitory computer-readable storage medium of any one of aspects 31C-35C, wherein the instructions further cause the one or more processors to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

Aspect 37C-the non-transitory computer-readable storage medium of any one of aspects 31C-35C, wherein the instructions further cause the one or more processors to: a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

Aspect 38C-the non-transitory computer-readable storage medium of any of aspects 31C-37C, wherein the device is configured to decode the quality metric message, and wherein the instructions further cause the one or more processors to: applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and displaying the processed picture.

Aspect 39C-the non-transitory computer-readable storage medium of any one of aspects 31C-38C, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

Aspect 40C-the non-transitory computer-readable storage medium of any of aspects 31C-38C, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

It is to be appreciated that certain acts or events of any of the techniques described herein can be performed in a different order, may be added, combined, or omitted entirely, depending on the example (e.g., not all of the described acts or events are necessary for the implementation of the techniques). Further, in some examples, an action or event may be performed concurrently, e.g., by multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially.

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

By way of example, and not limitation, such computer-readable storage media can 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 can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Further, any connection is properly termed a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but instead are directed to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

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 or discrete logic circuitry. Thus, the terms "processor" and "processing circuitry" as used herein may refer to any one of the foregoing structures or any other structure suitable for implementation of the techniques described herein. Additionally, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated into a combined codec. Furthermore, the techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses including a wireless handset, an Integrated Circuit (IC), or a set of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques but do not necessarily require realization by different hardware units. Rather, as noted above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units (including one or more processors as described above) in combination with appropriate software and/or firmware.

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

Claims

1. A method of processing video data, the method comprising:

receiving a picture; and

a quality metric message is coded that includes a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

2. The method of claim 1, further comprising:

coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

3. The method of claim 2, wherein the plurality of types of quality metrics comprise peak signal-to-noise ratio (PSNR).

4. The method of claim 2, wherein the plurality of types of quality metrics include two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

5. The method of claim 2, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

6. The method of claim 1, further comprising:

a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

7. The method of claim 1, further comprising:

a second quality metric message is coded that includes a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

8. The method of claim 1, wherein coding comprises decoding, and wherein the method further comprises:

applying post-processing techniques to the picture in accordance with the value of the quality metric to form a processed picture; and

displaying the processed picture.

9. The method of claim 1, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

10. The method of claim 1, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

11. An apparatus configured to process video data, the apparatus comprising:

a memory configured to store pictures; and

one or more processors implemented in circuitry and in communication with the memory, the one or more processors configured to:

receiving the picture; and

12. The apparatus of claim 11, wherein the one or more processors are further configured to:

coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from among a plurality of types of quality metrics indicated by the quality metric syntax element.

13. The apparatus of claim 12, wherein the plurality of types of quality metrics comprise peak signal-to-noise ratio (PSNR).

14. The apparatus of claim 12, wherein the plurality of types of quality metrics comprise two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

15. The apparatus of claim 12, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

16. The apparatus of claim 11, wherein the one or more processors are further configured to:

17. The apparatus of claim 11, wherein the one or more processors are further configured to:

18. The apparatus of claim 11, wherein the apparatus is configured to decode the quality metric message, and wherein the one or more processors are further configured to:

Displaying the processed picture.

19. The apparatus of claim 11, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

20. The apparatus of claim 11, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

21. An apparatus configured to process video data, the apparatus comprising:

a unit for receiving a picture; and

means for coding a quality metric message comprising a quality metric syntax element, wherein the quality metric syntax element indicates a value of a quality metric associated with the picture.

22. The apparatus of claim 21, further comprising:

means for coding a quality metric type syntax element in the quality metric message, wherein the quality metric type syntax element indicates a quality metric from a type of quality metric indicated by the quality metric syntax element among a plurality of types of quality metrics.

23. The apparatus of claim 22, wherein the plurality of types of quality metrics comprise peak signal-to-noise ratio (PSNR).

24. The apparatus of claim 22, wherein the plurality of types of quality metrics comprise two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

25. The apparatus of claim 22, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

26. The apparatus of claim 21, further comprising:

means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a sub-picture of the picture.

27. The apparatus of claim 21, further comprising:

means for coding a second quality metric message comprising a second quality metric syntax element, wherein the second quality metric syntax element indicates a second value of a second quality metric related to a region of interest of the picture.

28. The apparatus of claim 21, wherein the means for coding comprises means for decoding, and wherein the apparatus further comprises:

a unit for displaying the processed picture.

29. The apparatus of claim 21, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

30. The apparatus of claim 21, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).

31. 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:

receiving a picture; and

32. The non-transitory computer-readable storage medium of claim 31, wherein the instructions further cause the one or more processors to:

33. The non-transitory computer-readable storage medium of claim 32, wherein the plurality of types of quality metrics comprise peak signal-to-noise ratio (PSNR).

34. The non-transitory computer-readable storage medium of claim 32, wherein the plurality of types of quality metrics comprise two or more of: peak signal-to-noise ratio (PSNR), structural Similarity Index (SSIM), multi-scale structural similarity index (MS-SSIM), video Quality Metric (VQM), weighted PSNR (wPSNR), weighted to sphere uniform PSNR (WS-PSNR), sequence PSNR, sequence wPSNR, or sequence WS-PSNR.

35. The non-transitory computer-readable storage medium of claim 32, wherein the quality metric syntax element indicates the value of the quality metric indicated by the quality metric type syntax element.

36. The non-transitory computer-readable storage medium of claim 31, wherein the instructions further cause the one or more processors to:

37. The non-transitory computer-readable storage medium of claim 31, wherein the instructions further cause the one or more processors to:

38. The non-transitory computer-readable storage medium of claim 31, wherein the device is configured to decode the quality metric message, and wherein the instructions further cause the one or more processors to:

displaying the processed picture.

39. The non-transitory computer-readable storage medium of claim 31, wherein the quality metric message comprises a quality metric Supplemental Enhancement Information (SEI) message.

40. The non-transitory computer-readable storage medium of claim 31, wherein the quality metric message comprises a quality metric open bit stream unit (OBU).