WO2022072242A1 - Codage de données vidéo à l'aide d'informations de pose d'un utilisateur - Google Patents

Codage de données vidéo à l'aide d'informations de pose d'un utilisateur Download PDF

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Publication number
WO2022072242A1
WO2022072242A1 PCT/US2021/051997 US2021051997W WO2022072242A1 WO 2022072242 A1 WO2022072242 A1 WO 2022072242A1 US 2021051997 W US2021051997 W US 2021051997W WO 2022072242 A1 WO2022072242 A1 WO 2022072242A1
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WIPO (PCT)
Prior art keywords
reference picture
pose
warped
picture
current
Prior art date
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PCT/US2021/051997
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English (en)
Inventor
Arjun Sitaram
Ajit Venkat Rao
Vinay Melkote Krishnaprasad
Sriram AJAYKUMAR
Naveen Srinivasamurthy
Anand Prabhakar Satpute
Sandeep Kanakapura LAKSHMIKANTHA
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Qualcomm Incorporated
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Publication of WO2022072242A1 publication Critical patent/WO2022072242A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/167—Position within a video image, e.g. region of interest [ROI]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00—Geometric image transformations in the plane of the image
    • G06T3/04—Context-preserving transformations, e.g. by using an importance map
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T3/00—Geometric image transformations in the plane of the image
    • G06T3/18—Image warping, e.g. rearranging pixels individually
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/527—Global motion vector estimation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/573—Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/597—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding specially adapted for multi-view video sequence encoding

Definitions

  • This disclosure relates to video coding, including video encoding and video decoding.
  • Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones, so-called “smart phones,” video teleconferencing devices, video streaming devices, and the like.
  • Digital video devices implement video coding techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265/High Efficiency Video Coding (HEVC), and extensions of such standards.
  • the video devices may transmit, receive, encode, decode, and/or store digital video information more efficiently by implementing such video coding techniques.
  • Video coding techniques include spatial (intra-picture) prediction and/or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences.
  • a video slice e.g., a video picture or a portion of a video picture
  • video blocks which may also be referred to as coding tree units (CTUs), coding units (CUs) and/or coding nodes.
  • Video blocks in an intra-coded (I) slice of a picture are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same picture.
  • Video blocks in an inter-coded (P or B) slice of a picture may use spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures.
  • Pictures may be referred to as frames, and reference pictures may be referred to as reference frames.
  • this disclosure describes techniques for coding video data using pose information of a user.
  • the techniques of this disclosure may be applied by devices configured to present video data. to a user according to pose information of the user.
  • the video data may correspond to virtual reality, augmented reality, extended reality, or other types of data in which a user’s pose or direction of view is intended to change the video data presented.
  • video data is encoded by a source device, such as a server, personal computer, smart phone, or other device, and decoded and presented by a headset device worn by the user.
  • the headset device may provide pose information to the source device, which may modify encoded video data according to the pose information.
  • the source device may generate a base motion vector for a block from global motion according to the pose information, encode block-specific motion vectors using the base motion vector, or otherwise modify, warped reference pictures to generate additional or alternative reference pictures, or the like.
  • the destination device may perform reciprocal processes when decoding video data from the source device,
  • a method of coding video data includes determining, by a video coder of a device, pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; obtaining, by the video coder, a warped version of the reference picture according to differences between the current pose and the previous pose; and coding, by the video coder, one or more blocks of the current picture using the warped version of the reference picture.
  • a device for coding video data includes a memory' configured to store video data; and one or more processors implemented in circuitry and configured to: determine pose information representing a current pose of a user of tire device associated with a current picture of the video data and a previous pose of the user of the device associated with a reference picture of the video data; obtain a warped version of the reference picture according to differences betw een the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • a computer-readable storage medium has stored thereon instructions that, when executed, cause a processor of a device to: determine pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; obtain a warped version of the reference picture according to differences between the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • a device for coding video data includes means for determining pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; means for obtaining a warped version of the reference picture according to differences between the current pose and the previous pose; and means for coding one or more blocks of the current picture using the warped version of the reference picture.
  • 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 block diagram illustrating example components of a pose detection unit.
  • FIGS. 3A and 3B are block diagrams illustrating example systems for foveated rendering and coding of video data.
  • FIGS. 4A and 4B are graphs representing an example foveation transfer function.
  • FIGS 5 A- -5C are images representing example original, foveated, and decompressed images.
  • FIG. 6 is a block diagram illustrating example current and reference images in both an original form and a foveated form.
  • FIG. 7 is a block diagram illustrating an example warping unit configured to perform frame warping using foveated images according to the techniques of this disclosure.
  • FIG. 8 is a conceptual diagram illustrating example pictures according to the techniques of this disclosure.
  • FIG. 9 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.
  • FIG, 10 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.
  • FIG. 11 is a flowchart illustrating an example method for encoding a current block m accordance with the techniques of this disclosure.
  • FIG. 12 is a flowchart illustrating an example method for decoding a current block in accordance with the techniques of this disclosure.
  • FIG. 13 is a flowchart illustrating an example method for coding video data using pose information according to the techniques of this disclosure.
  • FIG. 1 is a block diagram illustrating an example video encoding and decoding system 100 that may perform the techniques of this disclosure.
  • the techniques of this disclosure are generally directed to coding (encoding and/or decoding) video data.
  • video data includes any data for processing a video.
  • video data may include raw, uncoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.
  • system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116, in this example.
  • source device 102 provides the video data to destination device 116 via a computer-readable medium 110.
  • source device 102 may comprise any of a wide range of devices, including desktop computers, notebook (i.e,, laptop) computers, mobile devices, tablet, computers, set-top boxes, telephone handsets such as smartphones, televisions, cameras, display devices, digital media players, video gaming consoles, video streaming device, or the like.
  • Destination device 116 may be a virtual reality headset, an augmented reality headset, an extended reality headset, or other such device.
  • source device 102 and destination device 116 may be equipped for wireless communication, and thus may be referred to as wireless communication devices.
  • a server device such as source device 102
  • renders XR content then compresses and transmits the XR content to a client head mounted display (HMD), such as destination device 116.
  • HMD head mounted display
  • source device 102 may further transmit render pose information to destination device 116.
  • Destination device 116 may then decompress and render the XR content after warping the content using the render pose and latest display pose information.
  • High bitrate video data may increase power consumption on a client HMD.
  • High bitrates may increase end-to-end latency, which may increase visual artifacts such as translational judder, and which may increase the likelihood of user nausea.
  • This disclosure further recognizes that better compression can reduce bandwidth consumption leading to additional communication channel capacity, allow for high quality video data on the same channel bandwidth, reduce power consumption in an overall split pipeline, and reduce overall end-to-end latency, which may mitigate associated visual artifacts.
  • video encoder 200 of source device 102 and video decoder 300 of destination device 116 may be configured to apply the techniques for coding video data, using pose information of a user.
  • source device 102 represents an example of a video encoding device
  • destination device 116 represents an example of a video decoding device.
  • source device 102 includes video source 104, memory 106, video encoder 200, warping unit 232, and output interface 108.
  • destination device 116 includes pose detection unit 124, input interface 122, video decoder 300, warping unit 322, memory 120, and display device 1 18.
  • Pose detection unit 124 generally determines and tracks a pose of a user of destination device 116.
  • Pose detection unit 124 may include one or more cameras, sensors, accelerometers, or other elements for determining a direction in which the user of destination device 116 is looking.
  • Pose detection unit may provide data representative of a current pose of the user of destination device 1 16 to source device 102, and in particular, to video source 104 of source de vice 102.
  • System 100 as shown in FIG. 1 is merely one example.
  • any digital video encoding and/or decoding device may perform techniques for coding video data using pose information of a user.
  • Source device 102 and destination device 116 are merely examples of such coding devices in which source device 102 generates coded video data for transmission to destination device 116.
  • This disclosure refers to a ‘"coding” device as a device that performs coding (encoding and/or decoding) of data.
  • video encoder 200 and video decoder 300 represent examples of coding devices, in particular, a video encoder and a video decoder, respectively.
  • 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.
  • system 100 may support one-way or two-way video transmission between source device 102 and destination device 116, e.g., for video streaming, video playback, video broadcasting, or video telephony.
  • video source 104 represents a source of video data (i.e., raw, uncoded video data) and provides a sequential series of pictures (also referred to as “frames”) of the video data to video encoder 200, which encodes data for the pictures.
  • Video source 104 of source device 102 may represent a device for generating video data, such as a video game engine. More particularly, video source 104 receives pose information from pose detection unit 124 of destination device 116 and generates video data according to the user’s current pose. For example, video source 104 may track the location of a virtual camera in a virtual scene, and orient the camera according to the pose information of the user of destination device 116. Video source 104 may then generate video data to be presented to the user according to the virtual camera or the pose information.
  • a sequence of render poses may describe global motion in a scene.
  • Video encoder 200 and video decoder 300 may exploit the global motion to achieve compression gains.
  • Video encoder 2.00 may transmit render poses for each frame in the bitstream, or separately, as auxiliary information, e.g., in supplemental enhancement information (SEI) messages.
  • SEI Supplemental Enhancement Information
  • Video encoder 200 encodes the generated video data.
  • Video encoder 200 may rearrange the pictures from the received order (sometimes referred to as “display order”) into a coding order for coding.
  • Video encoder 200 may generate a bitstream including encoded video data.
  • Source device 102 may then output the encoded video data via output interface 108 onto computer-readable medium 110 for reception and/or retrieval by, e.g., input interface 122 of destination device 116.
  • warping unit 232 also receives the pose information. Using the pose information, warping unit 232 may warp a previously decoded reference picture. For example, warping unit 232 may transform the previously decoded reference picture to correspond to new pose information.
  • Warping unit 232 may provide the warped reference picture to video encoder 200, which may store the warped reference picture in a decoded picture buffer thereof (or in memory 106). Video encoder 200 may then use the warped reference picture as a reference picture for encoding subsequent video data, e.g., by replacing an existing reference picture or adding the warped reference picture to one or more reference picture lists. Although shown separately from video encoder 200, in some examples, warping unit 232 may be included within video encoder 200.
  • a reference picture buffer may store a plurality of previously decoded reference pictures. Each of the reference pictures may have associated pose information.
  • video encoder 200 may warp two or more of the previously decoded reference pictures according to the pose information of the previously decoded reference pictures and the current picture to be encoded.
  • Video decoder 300 may similarly generate two or more warped reference pictures.
  • Video encoder 200 may select from the various warped reference pictures for each block of the current pi cture and signal which of the warped reference pictures to use as reference for a particular block.
  • warping unit 232 may warp reference frames using pose information to compensate for global motion between a reference frame and a source frame.
  • Warping units 232 and 322 may use a homography matrix, computed from the difference between the render poses of the reference and source frame pairs, to warp the reference frame.
  • disparity may be reduced, which may result in better inter-prediction, and therefore, reduced bitrate.
  • the bitstream may remain standard compliant but correctly decodable, as long as video decoder 300 interacts with warping unit 32 to similarly warp the reference frames.
  • auxiliary information may signal pose, depth, or any other information tor a custom warping to produce a better reference frame.
  • render depth information may be sent from source device 102. to destination device 116.
  • the render depth information can be a single depth value indicating a plane at that depth value relative to render pose and assumed to represent the geometric surface rendered.
  • the depth information may be provided by a plurality of plane parameters that describe an arbitrary plane relative to render pose that approximates the rendered geometry of the surface.
  • the warping unit may receive the single depth or plane parameters for one or both frames and may compute a homography for warping.
  • the rendered depth buffer or a downsampled version of the depth buffer or any other model of the depth buffer (such as a piece-wise planar model) may be signaled from source device 102 to destination device 1 16 for each rendered frame.
  • the warping module may use this information additionally to warp the reference frame to the pose of the current frame and register the warped reference frame better to tire current frame compared to simply using a homography that is based on pose differences.
  • video encoder 200 and/or warping unit 232 may determine a base motion vector according to global motion representing a change between the original reference picture and the warped reference picture.
  • Video encoder 200 may use the base motion vector as a motion vector predictor to encode one or more motion vectors for current blocks of a current picture. Using the base motion vector in this manner may reduce the magnitude of motion vector difference values signaled in the bitstream, which may reduce bitrates. Additionally or alternatively, video encoder 200 may use the base motion vector as a motion vector for predicting current blocks of the current picture.
  • video encoder 200 and/or warping unit 232. may determine a base motion vector from global motion according to the pose information differences. Then video encoder 200 may use the base motion vector to seed a motion estimation process, i.e., a motion search process, for blocks of a current picture. By using the base motion vector to seed the motion estimation search process, power consumed by video encoder 200 may be reduced, and complexity of the search process may also be reduced. In this manner, the video bitstream may remain standards compliant.
  • video encoder 200 may be configured to store pose information with each reference picture. 'Then, for a current picture, video encoder 200 may select a reference picture as the reference picture having the smallest difference relative to the pose information for the current picture. This may minimize disocclusions at edges of the pictures, and the bitstream may remain standards compliant.
  • video encoder 200 may select between a normal reference picture or a warped reference picture at a block level. Video encoder 200 may choose the reference picture that has the smallest pose difference relative to the current picture at the block level. Moreover, this difference may seed the motion search, resulting in lower power consumption in video encoder 200.
  • Using any or all of the techniques of this disclosure may reduce bitrate of a corresponding bi tstream produced by video encoder 200 and consumed by video decoder 300. These techniques may also mitigate visual artifacts (translational judder) due to lower end-to-end system latency. There may also be a power savings due to more efficient motion estimation.
  • split XR systems such as system 100
  • split XR systems use transport of rendered frames. Efficient compression of XR content, as discussed above, is important to companies investing in split XR systems.
  • Rendering of VR video data by source device 102 and presentation by destination device 116 may be referred to as “remote VR.”
  • Source device 102 may also be referred to as a “rendering machine” or “rendering device,” while destination device 116 may be referred to as a “remote client.”
  • Source device 102 and destination device 116 may generally perform an overall VR pipeline including rendering, encoding, streaming, decoding, and re-projection.
  • the various stages in the VR pipeline may generally operate on texture data. Per-stage performance may depend on texture dimensions. Current and future VR devices may be configured with higher resolution displays (e.g., 2Kx2K resolution) than conventional displays, which corresponds to an increase in computational demand required in each stage. Moreover, the bandwidth requirements of connections (e.g., on computer-readable medium 110) between source device 102 and destination device 116 also increase as resolution increases. Furthermore, higher resolutions may lead to higher per-stage latency and round-trip times (also referred to as “motion to render to photon” or “m2r2p” latency).
  • foveated compression may be used to address the issues related to increasing resolution.
  • high-resolution textures may be downscaled to lower resolutions (e.g., 2Kx2K resolution may be downscaled to 1 ,4Kxl .4K) for encoding and streaming.
  • video source 104 may generate 2Kx2K images.
  • source device 102 may foveate the 2Kx2K images to generate downscaled 1 ,4Kxl.4K images
  • video encoder 200 may encode the 1.4Kxl.4K images.
  • destination device 116 may decode the 1 ,4Kxl ,4K images and defoveate the decoded images for display by display device 1 18.
  • Foveation in this manner allows for greater compression without much noticeable distortion, because higher-quality content is typically located in the central fovea of the image, while lower-quality content is located along the periphery of the image.
  • greater texture compression can be achieved with negligible loss in visual quality.
  • Video encoder 200 and video decoder 300 may be configured to perform both the techniques for warping reference images according to differences in pose information for the reference images and current images and techniques for encoding and decoding foveated images. However, due to differences in the pose information, an object that was otherwise present in a periphery of a reference image may instead need to be presented closer to the central fovea of the warped reference image, or vice versa.
  • warping unit 232 of source device 102 and warping unit 322 of destination device 116 may be configured to, when warping a reference image, first defoviate the reference image, then warp the reference image, then refoveate the warped reference image for use as a reference image by video encoder 200 or video decoder 300.
  • Memory 106 of source device 102 and memory 120 of destination device 116 represent general purpose memories.
  • memories 106, 120 may store raw video data, e.g., raw video from video source 104 and raw; decoded video data from video decoder 300.
  • memories 106, 120 may store software instractions executable by, e.g., video encoder 200 and video decoder 300, respectively.
  • 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 memories for functionally similar or equivalent purposes.
  • memories 106, 120 may store encoded video data, e.g., output from video encoder 200 and input to video decoder 300. In some examples, portions of memories 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 1 10 may represent any type of medium or device capable of transporting the encoded video data from source device 102 to destination device 116. In one example, computer-readable medium 1 10 represents a communication medium to enable source device 102 to transmit encoded video data directly to destination device 1 16 in real-time, e.g,, via a radio frequency network or computer-based network.
  • Output interface 108 may modulate a transmission signal including the encoded video data, and input interface 122 may demodulate the received transmission signal, according to a communication standard, such as a wireless communication protocol.
  • the communication medium may comprise any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines.
  • the communication medium may form part of a packetbased network, such as a local area network, a wide-area network, or a global network such as the Internet.
  • the communication medium may include routers, switches, base stations, or any other equipment that may be useful to facilitate communication from source device 102 to destination device 116.
  • Output interface 108 and input interface 122 may represent wireless transmitters/receivers, modems, wired networking components (e.g., Ethernet cards), wireless communication components that operate according to any of a variety of IEEE 802. 11 standards, or other physical components.
  • output interface 108 and input interface 122 may be configured to transfer data, such as encoded video data, according to a cellular communication standard, such as 4G, 4G-LTE (Long-Term Evolution), LTE Advanced, 5G, or the like.
  • output interface 108 comprises a wireless transmitter
  • output interface 108 and input interface 122 may be configured to transfer data, such as encoded video data, according to other wireless standards, such as an IEEE 802,11 specification, an IEEE 802. 15 specification (e.g., ZigBeeTM), a BluetoothTM standard, or the like.
  • source device 102 and/or destination device 116 may include respective system-on-a-chip (SoC) devices.
  • SoC system-on-a-chip
  • source device 102 may include an SoC device to perform the functionality attributed to video encoder 200 and/or output interface 108
  • destination device 116 may include an SoC device to perform the functionality attributed to video decoder 300 and/or input interface 122.
  • the techniques of this disclosure may be applied to video coding in support of any of a variety of multimedia applications, such as over-the-air television broadcasts, cable television transmissions, satellite television transmissions, Internet streaming video transmissions, such as dynamic adaptive streaming over HTTP (DASH), or other applications.
  • multimedia applications such as over-the-air television broadcasts, cable television transmissions, satellite television transmissions, Internet streaming video transmissions, such as dynamic adaptive streaming over HTTP (DASH), or other applications.
  • DASH dynamic adaptive streaming over HTTP
  • Input interface 122 of destination device 116 receives an encoded video bitstream from computer-readable medium 110.
  • the encoded video bitstream may include signaling information defined by video encoder 200, which is also used by video decoder 300, such as syntax elements having values that describe characteristics and/or processing of video blocks or other coded units (e.g,, slices, pictures, groups of pictures, sequences, or the like).
  • Display device 1 18 displays decoded pictures of the decoded video data to a 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. Display device 118 may include two displays, one for each eye of a user, to achieve a three-dimensional rendering effect.
  • LCD liquid crystal display
  • OLED organic light emitting diode
  • video encoder 200 and video decoder 300 may each be integrated with an audio encoder and/or audio decoder, and may include appropriate MUX-DEMUX units, or other hardware and/or software, to handle multiplexed streams including both audio and video in a common data stream. If applicable, MUX-DEMUX units may conform to the ITU H.2.2.3 multiplexer protocol, or other protocols such as the user datagram protocol (UDP).
  • MUX-DEMUX units may conform to the ITU H.2.2.3 multiplexer protocol, or other protocols such as the user datagram protocol (UDP).
  • Video encoder 200 and video decoder 300 each may be implemented as any of a variety of suitable encoder and/or decoder circuitry, 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.
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • a device may store instractions 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.
  • Video encoder 200 and video decoder 300 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (CODEC) in a respective device.
  • a device including video encoder 200 and/or video decoder 300 may comprise an integrated circuit, a microprocessor, and/or a wireless communication device, such as a cellular telephone.
  • Video encoder 200 and video decoder 300 may operate according to a video coding standard, such as ITU-T H.265, also referred to as High Efficiency Video Coding (HE VC) or extensions thereto, such as the multi-view and/or scalable video coding extensions.
  • HE VC High Efficiency Video Coding
  • video encoder 200 and video decoder 300 may operate according to other proprietary or industry standards, such as Versatile Video Coding (VVC).
  • VVC Versatile Video Coding
  • a draft of the VVC standard is described in Bross, et al. “Versatile Video Coding (Draft 9),” Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 18 th Meeting:, 15-24 Apr., JVET-R2001-v8 (hereinafter “VVC Draft 9”).
  • the techniques of this disclosure are not limited to any particular coding standard.
  • video encoder 200 and video decoder 300 may perform block-based coding of pictures.
  • the term “block” generally refers to a structure including data to be processed (e.g., encoded, decoded, or otherwise used in the encoding and/or decoding process).
  • a block may include a two-dimensional matrix of samples of luminance and/or chrominance data.
  • video encoder 200 and video decoder 300 may code video data represented in a YUV (e.g., Y, Cb, Cr) format.
  • YUV e.g., Y, Cb, Cr
  • video encoder 200 and video decoder 300 may code luminance and chrominance components, where the chrominance components may include both red hue and blue hue chrominance components.
  • video encoder 200 converts received RGB formatted data to a YUV representation prior to encoding
  • video decoder 300 converts the YUV representation to the RGB format.
  • pre- and post-processing units may perform these conversions.
  • This disclosure may generally refer to coding (e.g., encoding and decoding) of pictures to include the process of encoding or decoding data of the picture.
  • this disclosure may refer to coding of blocks of a picture to include the process of encoding or decoding data tor the blocks, e.g., prediction and/or residual coding.
  • An encoded video bitstream generally includes a series of values for syntax elements representative of coding decisions (e.g., coding modes) and partitioning of pictures into blocks.
  • references to coding a picture or a block should generally be understood as coding values for syntax elements forming the picture or block.
  • HEVC defines various blocks, including coding units (C Us), prediction units (PUs), and transform units (TUs),
  • a video coder such as video encoder 200 partitions a coding tree unit (CTU) into CUs according to a quadtree structure. That is, the video coder partitions CTUs and CUs into four equal, nonoverlapping squares, and each node of the quadtree has either zero or four child nodes. Nodes without child nodes may be referred to as " leaf nodes,” and CUs of such leaf nodes may include one or more PUs and/or one or more TUs.
  • the video coder may further partition PUs and TUs.
  • a residual quadtree represents partitioning of TUs.
  • PUs represent inter-prediction data
  • TUs represent residual data.
  • CUs that are intra-predicted include intra-prediction information, such as an intra-mode indication.
  • video encoder 200 and video decoder 300 may be configured to operate according to VVC.
  • a video coder such as video encoder 200 partitions a picture into a plurality of coding tree units (CTUs).
  • Video encoder 200 may partition a CTU according to a tree structure, such as a quadtree-binary tree (QTBT) structure or Multi-Type Tree (MIT) structure.
  • QTBT structure removes the concepts of multiple partition types, such as the separation between CUs, PUs, and TUs of HEV C.
  • a QTBT structure includes two levels: a first level partitioned according to quadtree partitioning, and a second level partitioned according to binary tree partitioning.
  • a root node of the QTBT structure corresponds to a CTU.
  • Leaf nodes of the binary trees correspond to coding units (CUs).
  • blocks may be partitioned using a quadtree (QT) partition, a binary' tree (BT) partition, and one or more types of triple tree (TT) (also called ternary tree (TT)) partitions.
  • QT quadtree
  • BT binary' tree
  • TT triple tree
  • a triple or ternary tree partition is a partition where a block is split into three sub-blocks.
  • a triple or ternary tree partition divides a block into three sub-blocks without dividing the original block through the center.
  • the partitioning types in MTT e.g., QT, BT, and TT), may be symmetrical or asymmetrical.
  • video encoder 200 and video decoder 300 may use a single QTBT or MTT structure to represent each of the luminance and chrominance components, while in other examples, video encoder 200 and video decoder 300 mayuse two or more QTBT or MTT structures, such as one QTBT/MTT structure for the luminance component and another QTBT/MTT structure for both chrominance components (or two QTBT/MTT structures for respective chrominance components).
  • Video encoder 200 and video decoder 300 may be configured to use quadtree partitioning per HEVC, QTBT partitioning, MTT partitioning, or other partitioning structures. For purposes of explanation, the description of the techniques of this disclosure is presented with respect to QTBT partitioning. However, it should be understood that the techniques of this disclosure may also be applied to video coders configured to use quadtree partitioning, or other types of partitioning as well.
  • a CTU includes a coding tree block (CTB) of luma samples, two corresponding CTBs of chroma samples of a picture that has three sample arrays, or a CTB of samples of a monochrome picture or a picture that is coded using three separate color planes and syntax structures used to code the samples.
  • a CTB may be an NxN block of samples for some value of N such that the division of a component into CTBs is a partitioning.
  • the component may be an array or single sample from one of three arrays (luma and two chroma) for a picture in 4:2:0, 4:2:2, or 4:4:4 color format, or an array or a single sample of the array for a picture m monochrome format.
  • a coding block is an MxN block of samples for some values of M and N such that a division of a CTB into coding blocks is a partitioning.
  • the blocks may be grouped in various ways in a picture.
  • a 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 CTUs having a height equal to the height of the picture and a width specified by syntax elements (e.g., such as in a picture parameter set).
  • a tile row refers to a rectangular region of CTUs having a height specified by syntax elements (e.g., such as in a picture parameter set) and a width equal to the width of the picture.
  • a tile may be partitioned into multiple bricks, each of which may include one or more CTU rows within the tile.
  • a tile that is not partitioned into multiple bricks may also be referred to as a brick.
  • a brick that is a true subset of a tile may not be referred to as a tile.
  • the bricks in a picture may also be arranged in a slice.
  • a slice may be an integer number of bricks of a picture that may be exclusively contained in a single network abstraction layer (NAL) unit.
  • NAL network abstraction layer
  • a slice includes either a number of complete tiles or only a consecutive sequence of complete bricks of one tile.
  • an NxN CU generally has N samples in a vertical direction and N samples in a horizontal direction, where N represents a nonnegative integer value.
  • the samples in a CU may be arranged in rows and columns.
  • CUs need not necessarily have the same number of samples in the horizontal direction as in the vertical direction.
  • CUs may comprise MxM samples, where M is not necessarily equal to N.
  • Video encoder 200 encodes video data for CUs representing prediction and/or residual information, and other information.
  • the prediction information indicates how the CU is to be predicted in order to form a prediction block for the CU.
  • the residual information generally represents sample-by-sample differences between samples of the CU prior to encoding and the prediction block.
  • video encoder 2.00 may generally form a prediction block for the CU through inter-prediction or intra-prediction.
  • Inter-prediction generally refers to predicting the CU from data of a previously coded picture
  • intra-prediction generally refers to predicting the CU from previously coded data of the same picture.
  • video encoder 200 may generate the prediction block using one or more motion vectors.
  • Video encoder 200 may generally perform a motion search to identify a reference block that closely matches the CU, e.g., in terms of differences between the CU and the reference block.
  • Video encoder 200 may calculate a difference metric using a sum of absolute difference (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared differences (MSD), or other such difference calculations to determine whether a reference block closely matches the current CU.
  • video encoder 2.00 may predict the current CU using uni -directional prediction or bi-directional prediction.
  • VVC also provide an affine motion compensation mode, which may be considered an inter-prediction mode.
  • affine motion compensation mode video encoder 200 may determine two or more motion vectors that represent non- translational motion, such as zoom in or out, rotation, perspective motion, or other irregular motion types.
  • video encoder 200 may select an intra-prediction mode to generate the prediction block.
  • VVC provides sixty-seven intra-prediction modes, including various directional modes, as well as planar mode and DC mode.
  • video encoder 200 selects an intra-prediction mode that describes neighboring samples to a current block (e.g., a block of a CU) from which to predict samples of the current block. Such samples may generally be above, above and to the left, or to the left of the current block in the same picture as the current block, assuming video encoder 200 codes CTUs and CUs hr raster scan order (left to right, top to botom).
  • Video encoder 200 encodes data representing the prediction mode for a current block. For example, for inter-prediction modes, 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 uni -directional or bi-directional inter-prediction, for example, video encoder 200 may encode motion vectors using advanced motion vector prediction (AMVP) or merge mode. Video encoder 200 may use similar modes to encode motion vectors for affine motion compensation mode. [0074 ] Following prediction, such as intra-prediction or inter-prediction of a block, video encoder 200 may calculate residual data for the block.
  • AMVP advanced motion vector prediction
  • Video encoder 200 may calculate residual data for the block.
  • the residual data such as a residual block, represents sample by sample differences between the block and a prediction block for the block, formed using the corresponding prediction mode.
  • Video encoder 200 may apply one or more transforms to the residual block, to produce transformed data in a transform domain instead of the sample domain.
  • video encoder 200 may apply a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to residual video data.
  • DCT discrete cosine transform
  • an integer transform an integer transform
  • wavelet transform or a conceptually similar transform
  • video encoder 200 may apply a secondary’ transform following the first transform, such as a mode-dependent non-separable secondary' transform (MDNSST), a signal dependent transform, a Karhunen-Loeve transform (KLT), or the like.
  • Video encoder 200 produces transform coefficients following application of the one or more transforms.
  • video encoder 200 may perform quantization of the transform coefficients.
  • Quantization generally' refers to a process in which transform coefficients are quantized to possibly reduce the amount of data, used to represent the transform coefficients, providing further compression.
  • video encoder 200 may reduce the bit depth associated with some or all of the transform coefficients. For example, video encoder 200 may round an n-bit value down to an m-bit value during quantization, where n is greater than m.
  • video encoder 200 may perform a bitwise right-shift of the value to be quantized.
  • video encoder 2.00 may scan the transform coefficients, producing a one-dimensional vector from the two-dimensional matrix including the quantized transform coefficients.
  • video encoder 200 may utilize a predefined scan order to scan the quantized transform coefficients to produce a serialized vector, and then entropy encode the quantized transform coefficients of the vector.
  • video encoder 200 may perform an adaptive scan. After scanning the quantized transform coefficients to form tlie one-dimensional vector, video encoder 200 may entropy encode the onedimensional vector, e.g., according to context-adaptive binary arithmetic coding (CABAC).
  • CABAC context-adaptive binary arithmetic coding
  • Video encoder 200 may also entropy encode values for syntax elements describing metadata associated with the encoded video data for use by video decoder 300 in decoding the video data.
  • video encoder 200 may assign a context within a context model to a symbol to be transmitted .
  • the context may relate to, for example, whether neighboring values of the symbol are zero-valued or not.
  • Tlie probability determination may be based on a context assigned to the symbol.
  • Video encoder 200 may further generate syntax data, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, to video decoder 300, e.g., in a picture header, a block header, a slice header, or other syntax data, such as a sequence parameter set (SPS), picture parameter set (PPS), or video parameter set (VPS).
  • Video decoder 300 may likewise decode such syntax data to determine how to decode corresponding video data.
  • video encoder 200 may generate a bitstream including encoded video data, e.g., syntax elements describing partitioning of a picture into blocks (e.g., CUs) and prediction and/or residual information for the blocks.
  • video decoder 300 may receive the bitstream and decode the encoded video data.
  • video decoder 300 performs a reciprocal process to that performed by video encoder 200 to decode the encoded video data of the bitstream.
  • video decoder 300 may decode values for syntax elements of the bitstream using CABAC in a manner substantially similar to, albeit reciprocal to, the CABAC encoding process of video encoder 2.00.
  • the syntax elements may define partitioning information for partitioning a picture into CTUs, and partitioning of each CTU according to a corresponding partition structure, such as a QTBT structure, to define CUs of the CTU,
  • the syntax elements may further define prediction and residual information for blocks (e.g., CUs) of video data.
  • the residual information may be represented by, for example, quantized transform coefficients.
  • Video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of a block to reproduce a residual block for the block.
  • Video decoder 300 uses a signaled prediction mode (intra- or inter-prediction) and related prediction information (e.g,, motion information for inter-prediction) to form a prediction block for the block.
  • Video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block.
  • Video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along boundaries of the block,
  • This disclosure may generally refer to ‘"signaling” certain information, such as syntax elements.
  • the term “signaling” may generally refer to the communication of values for syntax elements and/or other data used to decode encoded video data. That is, video encoder 200 may signal values for syntax elements in the bitstream. In general, signaling refers to generating a value in the bitstream.
  • source device 102 may transport the bitstream to destination device 116 substantially in real time, or not in real time, such as might occur when storing syntax elements to storage device 112 for later retrieval by destination device 116.
  • FIG. 2 is a block diagram illustrating example components of pose detection unit 130.
  • pose detection unit 130 includes heads up display (HUD) cameras interface 132, HUD sensors interface 134, body sensors interface 136, and accessory sensors interface 138. These various interfaces may receive data from cameras and sensors attached to, e.g., a HUD (such as destination device 116 of FIG. 1), sensors attached to a user’s body, such as a vest or other clothing, and accessories such as handheld controllers.
  • the cameras may be light detection and range (LIDAR) sensors for detecting emitted lasers from base stations (not shown).
  • the other sensors may be inertial sensors such as gyroscopes and/or accelerometers.
  • LIDAR light detection and range
  • Pose detection unit 130 may detect pose information via any or all of HUD cameras interface 132, HUD sensors interface 134, body sensors interface 136, and accessory sensors interface 138. Pose detection unit 130 may use the pose information to determine a current pose associated with a user at a particular time. As discussed above with respect to FIG. 1 , warping units 232, 322 may use differences between pose information associated with video frames generated for the corresponding times to wasp a reference frame to fit a pose associated with a current frame. Then, video encoder 200 and video decoder 300 may use the warped reference frame to predict the current frame. [0085] FIGS. 3A and 3B are block diagrams illustrating example systems for foveated rendering and coding of video data. In particular, FIG.
  • rendering unit 140 depicts rendering unit 140, foveated downscaling unit 142, and video encoder 144. These elements may be included in source device 102 of FIG. 1.
  • rendering unit 140 may correspond to video source 104 and video encoder 144 may correspond to video encoder 200 in FIG. 1 .
  • Foveated downscaling unit 142 may also be included in source device 102 of FIG. 1, although no analogous unit is shown in the example of FIG. 1.
  • Foveated downscaling unit 142 may be configured to downscale a source image received from rendering unit 140 at a relatively high resolution (e.g., a 2Kx2K image) to a lower resolution (e.g., a 1.4Kxl.4K) image.
  • Video encoder 144 may then encode the foveated (downscaled) 1.4Kxl.4K image.
  • the foveated downscaling may be spatially non-uniform. That is, foveated downscaling unit 142 may preserve higher-quality content in a central fovea (where a user is likely to focus) of the source image, and apply higher downsampling to content closer to the periphery of the source image.
  • FIG. 3B depicts video decoder 146, foveated upscaling unit 148, and rendering unit. 149.
  • Video decoder 146 may correspond to video decoder 300 and rendering unit 149 may correspond to display device 1 18 of destination device 1 16 in FIG. 1 .
  • Foveated upscaling unit 148 may also be included in destination device 116, although no analogous unit is shown in the example of FIG. 1.
  • Video decoder 146 may decode a 1 ,4Kxl.4K image
  • foveated upscaling unit 148 may defoviate (upscale) the decoded image to 2Kx2K
  • rendering unit 149 may render and display the upscaled image.
  • foveated compression yielded a savings of roughly 10ms in m2r2p latency
  • FIGS. 4A and 4B are graphs representing an example foveation transfer function.
  • FIG. 4A depicts a 3D view 400 of the foveation transfer function
  • FIG. 4B depicts a top vie w' 402 of tire foveated transfer function.
  • values along the Z-axis (height) represent a sampling density tor the foveation transfer function.
  • Values along the x and y axes correspond to normalized coordinates in the width and height dimensions of the original images.
  • the downscaling preserves pixels 1 : 1. while sampling density decreases (and thus compression increases) towards the periphery.
  • FIGS 5A-5C are images representing example original, foveated, and decompressed images.
  • FIG. 5A depicts an example original image 404.
  • FIG. 5B depicts an example foveated downscaled image 406.
  • pixels nearer the center of foveated downscaled image 406 match the corresponding pixels of original image 404.
  • foveated downscaled image 406 appears “pulled in” at the periphery'.
  • FIG. 5C depicts decompressed image 408, which corresponds to a defoviated version of foveated downscaled image 406.
  • original image 404 is a 2Kx2K resolution image
  • foveated downscaled image 406 is a 1 ,4Kxl.4K resolution image
  • decompressed image 408 is also a 2Kx2K resolution image
  • foveation in this example is performed on a 16x16 vertex grid, with a fovea size of 40 degrees and a field of view of 90 degrees.
  • FIG. 6 is a block diagram illustrating example current and reference images in both an original form and a foveated form.
  • foveated compression in one image as discussed above is performed agonstically to foveated compression that happens in prior images.
  • FIG. 6 depicts an example of a rendering unit 410 that generates two images: reference frame 412 and current frame 416.
  • Current frame 416 depicts object 414 at a different position than the same object 414’ as depicted in reference frame 412.
  • the object may have moved either locally or globally between the times when rendering unit 410 generated reference frame 412 and current frame 416. That is, for example, a user may have directed their attention toward the object, or the object may have moved in front, of the user’s central field of view.
  • FIG. 6 also depicts foveated downscaling unit 416, which performs foveated downscaling of reference frame 412 to generate foveated reference frame 418 and of current frame 416 to generate foveated current frame 420.
  • foveated cun-ent frame 420 depicts object 422 (corresponding to object 414) at a position that is near the center of foveated current frame 420, and thus, the foveation does not impact the shape of object 422 much.
  • object 414’ was nearer the periphery of reference frame 412, object 422’ as depicted in foveated reference frame 418 is distorted relative to object 414’ as depicted in reference frame 412.
  • FIG. 7 is a block diagram illustrating an example warping unit 450 configured to perform frame warping using foveated images according to the techniques of this disclosure.
  • warping unit 450 includes defoviation unit 452, frame warp unit 454, and refoviation unit 456.
  • Warping unit 232 and warping unit 322 of FIG. 1 may include components similar to those of warping unit 450, when performing techniques including a combination of foveated compression and reference frame warping.
  • defoviation unit 452 may initially defoviate the foveated reference frame. That is defoviation unit 452 may receive the reference frame and undo the foveated compression (i.e., expand the reference frame to its full original resolution).
  • Frame warp unit 454 may then use pose information for the reference frame and a current frame to warp the reference frame.
  • Refoviation unit 456 may then refoveate the warped reference frame (thereby spatially recompressing the warped reference frame) and output the warped reference frame for use as a warped reference frame for coding the current frame.
  • the fovea or region with 1 : 1 sub-sampling for foveated compression was assumed to be the center of an image.
  • this fovea may be determined by the eye pose of the user.
  • an eye-tracking unit on the device may indicate where the eyes of the user are focusing in the display, so eye pose may also be sent from the XR device to the rendering device or server.
  • Foveated compression of a frame may be such that 1 : 1 sub-sampling is performed in a region of that frame that corresponds to the gaze direction/eye pose of the user and outwards of it, a higher level of spatial compression may be effected.
  • defoviation unit 452 may receive eye-pose information corresponding to the reference frame to defoveate the reference frame appropriately, and refoviation unit 456 may receive eye-pose information of the current frame to refoveate the warped reference frame so that its fovea is in alignment with the fovea of the current frame.
  • synchronization may be maintained between encoder and decoder by sending the eye-pose information in supplemental enhancement information (SEI) fields of packets corresponding to each frame and using that in the corresponding warping module at video decoder 300.
  • SEI Supplemental Enhancement information
  • Both a video encoder (such as video encoder 200) and a video decoder (such as video decoder 300) may include or interface with a warping unit similar to warping unit 450.
  • the video decoder may be synchronized with the video encoder, and reference frame defoviation, warping, and refoviation may be performed for both video encoding and video decoding.
  • reference frame defoviation, warping, and refoviation may be performed for both video encoding and video decoding.
  • FIG. 8 is a conceptual diagram illustrating example pictures according to the techniques of this disclosure.
  • FIG. 8 illustrates an example reference picture 150, and an example current picture 154.
  • Reference picture 150 includes reference block 160, to which motion vector 164 of current block 162 of current picture 154 refers.
  • FIG. 8 also illustrates warped reference picture 152. That is, a warping unit, such as warping unit 232 or warping unit 322. of FIG. 1, may warp reference pi cture 150 to form warped reference picture 152. As shown in FIG. 8, the warping process results in reference block 166, which generally corresponds to reference block 160, being located in a slightly different position within warped reference picture 152 than reference block 160 in reference picture 150. For example, the warping process may account for pose data from pose detec tion unit 124 of FIG . 1 .
  • current block 168 of current picture 156 can be predicted from reference block 166 using motion vector 170.
  • motion vector 170 is substantially smaller than motion vector 164.
  • a coded version of motion vector 170 may consume substantially fewer bits tan a coded version of motion vector 164.
  • reference block 166 may be more similar to current block 168, thereby reducing the bitrate of a coded representation of current block 168.
  • forming warped reference picture 152 and coding blocks of current picture 156 relative to warped reference picture 152 may reduce bitrate, which may improve the process of video coding.
  • FIG. 9 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure.
  • FIG. 9 is provided for purposes of explanation and should not be considered limiting of the techniques as broadly exemplified and described in this disclosure.
  • this disclosure describes video encoder 2.00 in the context of video coding standards such as the ITU-T H.265/HEVC video coding standard and the VVC video coding standard in development. How ever, the techniques of this disclosure are not limited to these video coding standards and are applicable generally to other video encoding and decoding standards.
  • 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, warping unit interface 234, 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 2.08, 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.
  • the units of video encoder 200 may be implemented as one or more circuits or logic elements as part of hardware circuitry', or as part of a processor, ASIC, or FPGA. Moreover, video encoder 200 may include additional or alternative processors or processing circuitry' to perform these and other functions.
  • Video data memory 230 may' store video data to be encoded by' the components of video encoder 200.
  • Video encoder 200 may receive the video data stored in video data memory'' 230 from, for example, video source 104 (FIG. 1).
  • DPB 218 may act as a reference picture memory that stores reference video data for use in prediction of subsequent video data by' video encoder 200.
  • Video data memory' 230 and DPB 218 may be formed by any of a variety' of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory' devices.
  • Video data memory 230 and DPB 218 may be provided by the same memory' device or separate memory'- devices.
  • video data memory'- 230 may be on-chip with other components of video encoder 200, as illustrated, or off-chip relative to those components.
  • reference to video data memory' 230 should not be interpreted as being 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. Rather, reference to video data memory' 230 should be understood as reference memory' that stores video data that video encoder 200 receives for encoding (e.g., video data for a current block that is to be encoded). Memory 106 of FIG. 1 may also provide temporary storage of outputs from the various units of video encoder 200.
  • the various units of FIG. 9 are illustrated to assist with understanding the operations performed by video encoder 200,
  • the units may be implemented as fixed- function circuits, programmable circuits, or a combination thereof.
  • Fixed-function circuits refer to circuits that provide particular functionality, and are preset on tire operations that can be performed.
  • Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed.
  • programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware.
  • Fixed-function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable.
  • one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, the one or more units may be integrated circuits.
  • Video encoder 200 may include arithmetic logic units (ALUs), elementary function units (EFUs), digital circuits, analog circuits, and/or programmable cores, formed from programmable circuits.
  • ALUs arithmetic logic units
  • EFUs elementary function units
  • digital circuits analog circuits
  • programmable cores formed from programmable circuits.
  • memory 106 FIG. 1 may store instructions (e.g., object code) of the software that video encoder 200 receives and executes, or another memory within video encoder 200 (not shown) may store such instructions.
  • Video data memory 230 is configured to store received video data.
  • Video encoder 200 may retrieve a picture of the video data from video data memory' 230 and provide the video data to residual generation uni t 204 and mode selection unit 202.
  • Video data in video data memory 230 may be raw' video data that is to be encoded.
  • Mode selection unit 202 includes motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226.
  • Mode selection unit 202 may include additional functional units to perform video prediction in accordance with other prediction modes.
  • mode selection unit 202 may include a palette unit, an intra-block copy unit (which may be part of motion estimation unit 22.2 and/or motion compensation unit 224), an affine unit, a linear model (LM) unit, or the like.
  • LM linear model
  • Mode selection unit 202 generally coordinates multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values for such combinations.
  • the encoding parameters may include partitioning of CTUs into CUs, prediction modes for the CUs, transform types for residual data of the CUs, quantization parameters for residual data of the CUs, and so on.
  • Mode selection unit 202 may ultimately select the combination of encoding parameters having rate-distortion values that are better than the other tested combinations.
  • Video encoder 200 may partition a picture retrieved from video data memory 230 into a series of CTUs, and encapsulate one or more CTUs within a slice.
  • Mode selection unit 202 may partition a CTU of the picture in accordance with a tree structure, such as the QTBT structure or the quad-tree structure of H EVC described above.
  • video encoder 2.00 may form one or more CUs from partitioning a CTU according to the tree structure.
  • Such a CU may also be referred to generally as a “video block” or “block.”
  • mode selection unit 202 also controls the components thereof (e.g., motion estimation unit 222, motion compensation unit 224, and intra-prediction unit 226) to generate a prediction block for a current block (e.g., a current CU, or in HEVC, the overlapping portion of a PU and a TU).
  • 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).
  • motion estimation unit 222 may calculate a value representative of how similar a potential reference block is to the current block, e.g., according to sum of absolute difference (SAD), sum of squared differences (SSD), mean absolute difference (MAD), mean squared differences (MSD), or the like. Motion estimation unit 222 may generally perform these calculations using sample-by-samplc differences between the current block and the reference block being considered. Motion estimation unit 222 may identify a reference block having a lowest value resulting from these calculations, indicating a reference block that most closely matches the current block. As discussed above, in some examples, motion estimation unit 222 may use a base motion vector, calculated according to differences in pose information between a current picture and a reference picture, and initialize (or “seed”) the motion search using the base motion vector.
  • SAD sum of absolute difference
  • SSD sum of squared differences
  • MAD mean absolute difference
  • MSD mean squared differences
  • Motion estimation unit 222 may form one or more motion vectors (M Vs) that define the positions of the reference blocks in the reference pictures relative to the position of the current block in a current picture. Motion estimation unit 222 may then provide the motion vectors to motion compensation unit 224. For example, for unidirectional inter-prediction, motion estimation unit 222 may provide a single motion vector, whereas for bi-directional inter-prediction, motion estimation unit 222 may provide two motion vectors. Motion compensation unit 224 may then generate a prediction block using the motion vectors. For example, motion compensation unit 224 may retrieve data of tire reference block using the motion vector. As another example, if the motion vector has fractional sample precision, motion compensation unit 224 may interpolate values for the prediction block according to one or more interpolation filters.
  • M Vs motion vectors
  • motion compensation unit 224 may retrieve data for two reference blocks identified by respective motion vectors and combine the retrieved data, e.g., through sample -by-sam ple averaging or weighted averaging.
  • intraprediction unit 2.26 may generate the prediction block from samples neighboring the current block. For example, for directional modes, intra-prediction unit 226 may generally mathematically combine values of neighboring samples and populate these calculated values in the defined direction across the current block to produce the prediction block. As another example, for DC mode, intra-prediction unit 2.26 may calculate an average of the neighboring samples to the current block and generate the prediction block to include this resulting average for each sample of the prediction block.
  • Mode selection unit 202 provides the prediction block to residual generation unit 204.
  • Residual generation unit 204 receives a raw, uncoded version of the current block from video data memory 230 and the prediction block from mode selection unit 202. Residual generation unit 204 calculates sample-by-sample differences between the current block and the prediction block. The resulting sample-by-sample differences define a residual block for the current block.
  • residual generation unit 204 may also determine differences between sample values in the residual block to generate a residual block using residual differential pulse code modulation (RDPCM).
  • RPCM residual differential pulse code modulation
  • residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.
  • each PU may be associated with a luma prediction unit and corresponding chroma prediction units.
  • Video encoder 2.00 and video decoder 300 may support PUs having various sizes. As indicated above, the size of a CU may refer to the size of the luma coding block of the CU and the size of a PU may refer to the size of a luma prediction unit of the PU.
  • video encoder 200 may support PU sizes of 2Nx2N or NxN for intra prediction, and symmetric PU sizes of 2Nx2N, 2NxN, Nx2N, NxN, or similar for inter prediction.
  • Video encoder 200 and video decoder 300 may also support asymmetric partitioning for PU sizes of 2NxnU, 2NxnD, nLx2N, and nRx2N for inter prediction.
  • each CU may be associated with a luma coding block and corresponding chroma coding blocks.
  • the size of a CU may refer to the size of tire luma coding block of the CU.
  • the video encoder 200 and video decoder 300 may support CU sizes of 2Nx2N, 2NxN, orNx2N .
  • mode selection unit 202 For other video coding techniques such as intra-biock copy mode coding, affinemode coding, and linear model (LM) mode coding, as some examples, mode selection unit 202, via respective units associated with the coding techniques, generates a prediction block for the current block being encoded. In some examples, such as palette mode coding, mode selection unit 202 may not generate a prediction block, and instead may generate syntax elements that indicate the manner in which to reconstruct the block based on a selected palete. In such modes, mode selection unit 202 may provide these syntax elements to entropy encoding unit 220 to be encoded.
  • mode selection unit 202 via respective units associated with the coding techniques, generates a prediction block for the current block being encoded.
  • mode selection unit 202 may not generate a prediction block, and instead may generate syntax elements that indicate the manner in which to reconstruct the block based on a selected palete. In such modes, mode selection unit 202 may provide these syntax elements to entropy encoding unit 220 to be encoded
  • residual generation unit 204 receives the video data for the current block and the corresponding prediction block. Residual generation unit 204 then generates a residual block for the current block. To generate the residual block, residual generation unit 204 calculates sample-by-sample differences between the prediction block and the current block.
  • Transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a ‘‘transform coefficient block”).
  • Transform processing unit 206 may apply various transforms to a residual block to form the transform coefficient block.
  • transform processing unit 206 may apply a discrete cosine transform (DCT), a directional transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to a residual block.
  • transform processing unit 206 may perform multiple transforms to a residual block, e.g., a primary transform and a secondary transform, such as a rotational transform.
  • transform processing unit 2.06 does not apply transforms to a residual block.
  • Quantization unit 208 may quantize the transform coefficients in a transform coefficient block, to produce a quantized transform coefficient block. Quantization unit 208 may quantize transform coefficients of a transform coefficient block according to a quantization parameter (QP) value associated with the current block. Video encoder 200 (e.g., via mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient blocks associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce loss of information, and thus, quantized transform coefficients may have lower precision than the original transform coefficients produced by transform processing unit 206.
  • QP quantization parameter
  • Inverse quantization unit 210 and inverse transform processing unit 212 may apply inverse quantization and inverse transforms to a quantized transform coefficient block, respectively, to reconstruct a residual block from the transform coefficient block.
  • Reconstruction unit 214 may produce a reconstructed block corresponding to the current block (albeit potentially with some degree of distortion) based on the reconstructed residual block and a prediction block generated by mode selection unit 202. For example, reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples from the prediction block generated by mode selection unit 202. to produce the reconstructed block.
  • Filter unit 216 may perform one or more filter operations on reconstructed blocks. For example, filter unit 216 may perform deblocking operations to reduce blockiness artifacts along edges of CUs. Operations of filter unit 216 may be skipped, in some examples.
  • Warping unit interface 234 represents a physical or logical interface (e.g., an application programming interface (API)) by which to send data to and receive data from a warping unit, such as warping unit 232 (FIG. 1, not shown in FIG. 9) or warping unit 450 of FIG. 7.
  • a warping unit such as warping unit 232 (FIG. 1, not shown in FIG. 9) or warping unit 450 of FIG. 7.
  • video encoder 200 may send a reconstructed reference picture (which may have been foveated prior to encoding) and pose information to warping unit 2.32 and receive a warped reference picture from warping unit 232.
  • filter unit 216 may additionally store the unwarped reference picture to DPB 218.
  • the warping unit may be included within video encoder 200, in which case warping unit interface 234 as shown may be replaced with the warping unit itself.
  • the warping unit may correspond to warping unit 450 of FIG. 7.
  • the warping unit may be a dedicated hardware unit for warping pictures according to pose information (e.g., directional pose information, eye-based focus information, or the like, as discussed herein).
  • the warping unit may correspond to warping unit 232 of FIG. 1.
  • the warping unit may receive a frame to be warped and pose information representing a current pose and the pose associated with the frame, and may receive additional metadata, such as depth information.
  • the w arping unit may output a warped frame based on the received frame, the pose information, and any other received metadata.
  • Video encoder 200 stores reconstructed (and potentially warped) pictures in DPB 218.
  • Motion estimation unit 222 and motion compensation unit 224 may retrieve a reference picture (which may be warped, according to the techniques of this disclosure) from DPB 218, to inter-predict blocks of subsequently encoded pictures.
  • intra-prediction unit 226 may use reconstructed blocks in DPB 218 of a current picture to intra-predict other blocks in the current picture.
  • 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 quantized transform coefficient blocks from quantization unit 208. As another example, entropy encoding unit 220 may entropy encode prediction syntax elements (e.g., motion information for inter-prediction or intra-mode information for intra-prediction) from mode selection unit 202. Entropy encoding unit 220 may perform one or more entropy encoding operations on the syntax elements, which are another example of video data, to generate entropy-encoded data.
  • prediction syntax elements e.g., motion information for inter-prediction or intra-mode information for intra-prediction
  • entropy encoding unit 220 may perform a context-adaptive variable length coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2.V) length coding operation, a syntax-based context-adaptive binary' arithmetic coding (SBAC) operation, a Probability Interval Partitioning Entropy (PIPE) coding operation, an Exponential -Golomb encoding operation, or another type of entropy encoding operation on the data.
  • entropy encoding unit 22.0 may operate in bypass mode where syntax elements are not entropy encoded.
  • Video encoder 200 may output a bitstream that includes the entropy encoded syntax elements needed to reconstruct blocks of a slice or picture.
  • entropy encoding unit 220 may output the bitstream.
  • the operations described above are described with respect to a block. Such description should be understood as being operations for a luma coding block and/or chroma coding blocks.
  • the lurna coding block and chroma coding blocks are luma and chroma components of a CU.
  • the luma coding block and the chroma coding blocks are luma and chroma components of a PU.
  • operations performed with respect to a luma coding block need not be repeated for the chroma coding blocks.
  • operations to identify a motion vector (MV) and reference picture for a luma coding block need not be repeated for identifying a MV and reference picture for die chroma blocks. Rather, the MV for the luma coding block may be scaled to determine the MV for the chroma blocks, and the reference picture may be the same.
  • the intraprediction process may be the same for the luma coding block and the chroma coding blocks.
  • FIG, 10 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure.
  • FIG. 10 is provided for purposes of explanation and is not limiting on the techniques as broadly exemplified and described in this disclosure.
  • this disclosure describes video decoder 300 according to the techniques of WC and HEVC (ITU-T H.265).
  • the techniques of this disclosure may be performed by video coding devices that are configured to other video coding standards.
  • 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, warping unit interface 324, and decoded picture buffer (DPB) 314.
  • CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, and DPB 314 may be implemented in one or more processors or in processing circuitry.
  • video decoder 300 may be implemented as one or more circuits or logic elements as part of hardware circuitry’, or as part of a processor, ASIC, or FPGA.
  • video decoder 300 may' include additional or alternative processors or processing circuitry to perform these and other functions.
  • Prediction processing unit 304 includes motion compensation unit 316 and intraprediction unit 318. Prediction processing unit 304 may include additional units to perform prediction in accordance with other prediction modes. As examples, prediction processing unit 304 may include a palette unit, an intra-block copy unit (which mayform part of motion compensation unit 316), an affine unit, a linear model (LM) unit, or the like. In other examples, video decoder 300 may include more, fewer, or different functional components .
  • CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by the components of video decoder 300.
  • the video data stored in CPB memory 320 may be obtained, for example, from computer-readable medium 110 (FIG. 1 ).
  • CPB memory 320 may include a CPB that stores encoded video data (e.g., syntax elements) from an encoded video bitstream.
  • CPB memory 320 may store video data other than syntax elements of a coded picture, such as temporary data representing outputs from the various units of video decoder 300.
  • DPB 314 generally stores decoded pictures, which video decoder 300 may output and/or use as reference video data when decoding subsequent data or pictures of the encoded video bitstream.
  • CPB memory 320 and DPB 314 may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices.
  • DRAM dynamic random access memory
  • SDRAM synchronous DRAM
  • MRAM magnetoresistive RAM
  • RRAM resistive RAM
  • CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices.
  • CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip relative to those components.
  • video decoder 300 may retrieve coded video data from memory 120 (FIG. 1). That is, memory 120 may store data as discussed above with CPB memory 320. Likewise, memory- 120 may store instructions to be executed by video decoder 300, when some or all of the functionality of video decoder 300 is implemented in software to be executed by processing circuitry of video decoder 300.
  • the various units shown in FIG. 10 are illustrated to assist with understanding the operations performed by video decoder 300.
  • the units may be implemented as fixed-function circuits, programmable circuits, or a combination thereof. Similar to FIG. 9, fixed-function circuits refer to circuits that provide particular functionality, and are preset on the operations that can be performed.
  • Programmable circuits refer to circuits that can be programmed to perform various tasks, and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware.
  • Fixed- function circuits may execute software instructions (e.g., to receive parameters or output parameters), but the types of operations that the fixed-function circuits perform are generally immutable.
  • the one or more units may be distinct circuit blocks (fixed-function or programmable), and in some examples, the one or more units may be integrated circuits.
  • Video decoder 300 may include ALUs, EFUs, digital circuits, analog circuits, and/or programmable cores formed from programmable circuits.
  • on-chip or off-chip memory may store instructions (e.g., object code) of the software that video decoder 300 receives and executes.
  • Entropy decoding unit 302. may receive encoded video data from the CPB and entropy decode the video data to reproduce syntax elements.
  • Prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, and filter unit 312 may generate decoded video data based on the syntax elements extracted from the bitstream.
  • video decoder 300 reconstructs a picture on a block-by-block basis.
  • Video decoder 300 may perform a reconstruction operation on each block individually (where the block currently being reconstructed, i.e., decoded, may be referred to as a “current block”).
  • Entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of a quantized transform coefficient block, as well as transform information, such as a quantization parameter (QP) and/or transform mode indication(s).
  • Inverse quantization unit 306 may use the QP associated with the quantized transform coefficient block to determine a degree of quantization and, likewise, a degree of inverse quantization for inverse quantization unit 306 to apply.
  • Inverse quantization unit 306 may, tor example, perform a bitwise left-shift operation to inverse quantize the quantized transform coefficients. Inverse quantization unit 306 may thereby form a transform coefficient block including transform coefficients.
  • 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.
  • inverse transform processing unit 308 may apply an inverse DOT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotational transform, an inverse directional transform, or another inverse transform to the transform coefficient block.
  • KLT Karhunen-Loeve transform
  • prediction processing unit 304 generates a prediction block according to prediction information syntax elements that were entropy decoded by entropy decoding unit 302. For example, if the prediction information syntax elements indicate that the current block is inter-predicted, motion compensation unit 316 may generate the prediction block. In this case, the prediction information syntax elements may indicate a reference picture in DPB 314 from which to retrieve a reference block, as well as a motion vector identifying a location of the reference block in the reference picture relative to the location of the current block in the current picture. Motion compensation unit 316 may generally perform the inter-prediction process in a manner that is substantially similar to that described with respect to motion compensation unit 224 (FIG. 9).
  • intra-prediction unit 318 may generate the prediction block according to an intra-prediction mode indicated by the prediction information syntax elements. Again, intra-prediction unit 318 may generally perform the intra-prediction process in a manner that is substantially similar to that described with respect to intra-prediction unit 2.2.6 (FIG. 9). Intra-prediction unit 318 may retrieve data of neighboring samples to the current block from DPB 314.
  • Reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.
  • Filter unit 312 may perform one or more filter operations on reconstructed blocks.
  • filter unit 312. may perform deblocking operations to reduce blockiness artifacts along edges of the reconstructed blocks. Operations of filter unit 312 are not necessarily performed in all examples.
  • Warping unit interface 324 represents a physical or logical interface (e.g., an application programming interface (API)) by which to send data to and receive data from a warping unit, such as warping unit 322 (FIG. I , not shown in FIG. 10).
  • a warping unit such as warping unit 322 (FIG. I , not shown in FIG. 10).
  • video decoder 300 may send a reconstructed reference picture and pose information to warping unit 322. and receive a warped reference picture from warping unit 322.
  • filter unit 312 may additionally store the unwarped reference picture to DPB 314.
  • the warping unit may be included within video decoder 300, in which case warping unit interface 324 as shown may be replaced with the warping unit itself.
  • the warping unit may correspond to warping unit 450 of FIG. 7.
  • Video decoder 300 may store the reconstructed blocks in DPB 314, For instance, in examples where operations of filter unit 312 are not performed, reconstruction unit 310 may store reconstructed blocks to DPB 314. In examples where operations of filter unit 312. are performed, filter unit 312 may store the filtered reconstructed blocks to DPB 314. As discussed above, DPB 314 may provide reference information, such as samples of a current picture for intra-prediction and previously decoded pictures for subsequent motion compensation, to prediction processing unit 304. Moreover, video decoder 300 may output decoded pictures from DPB 314 for subsequent presentation on a display device, such as display device 118 of FIG. 1. [0146] FIG.
  • the current block may comprise a current CU.
  • video encoder 200 FIGGS. 1 and 3
  • other devices may be configured to perform a method similar to that of FIG. 11.
  • video encoder 200 of FIG, 1 may receive pose information (344), e.g., from destination device 116, Video encoder 200 may send the pose information to a warping unit (346), such as warping unit 232 (FIG. 1). Video encoder 200 may also encode the pose information, e.g., in an SEI message. Video encoder 200 may further send a reference picture to warping unit 232. In response to sending the reference picture and the pose information, video encoder 200 may receive a warped reference picture from warping unit 232 (348).
  • pose information 344
  • Video encoder 200 may send the pose information to a warping unit (346), such as warping unit 232 (FIG. 1).
  • Video encoder 200 may also encode the pose information, e.g., in an SEI message.
  • Video encoder 200 may further send a reference picture to warping unit 232.
  • video encoder 200 may receive a warped reference picture from warping unit 232 (348).
  • Video encoder 200 may then predict the current block (350). For example, video encoder 200 may form a prediction block for the current, block using the warped reference picture. Video encoder 200 may initialize a motion search using a base motion vector calculated for the current picture and the reference picture. Additionally or alternatively, video encoder 200 may use the base motion vector as a motion vector predictor to predict and encode a motion vector for the current block.
  • Video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, video encoder 200 may calculate a difference between the original, uncoded block and the prediction block for the current block. Video encoder 200 may then transform and quantize coefficients of the residual block (354). Next, video encoder 200 may scan the quantized transform coefficients of the residual block (356). During the scan, or following the scan, video encoder 200 may entropy encode the coefficients (358). For example, video encoder 200 may encode the coefficients using CAVLC or CABAC. Video encoder 200 may then output the entropy encoded data of the block (360).
  • FIG. 12 is a flowchart illustrating an example method for decoding a current block in accordance with the techniques of this disclosure.
  • the current block may comprise a current CU.
  • video decoder 300 FIGGS. 1 and 4
  • other devices may be configured to perform a method similar to that of FIG. 12.
  • video decoder 300 of FIG. 1 may receive pose information (364), e.g., from pose detection unit 124 and/or from source device 102, e.g., in the form of an SEI message.
  • Video decoder 300 may send the pose information to a warping unit (366), such as warping unit 324 (FIG. 1), Video decoder 300 may further send a reference picture to warping unit interface 324.
  • video decoder 300 may receive a warped reference picture from warping unit interface 324 (368).
  • Video decoder 300 may receive entropy encoded data for the current block, such as entropy encoded prediction information and entropy encoded data for coefficients of a residual block corresponding to the current block (370). Video decoder 300 may entropy decode the entropy encoded data to determine prediction information for the current block and to reproduce coefficients of the residual block (372). Video decoder 300 may predict the current block (374), e.g., using an inter-prediction mode as indicated by the prediction information for the current block and referring to the warped reference picture, to calculate a prediction block for the current block. Video decoder 300 may then inverse scan the reproduced coefficients (376), to create a block of quantized transform coefficients. Video decoder 300 may then inverse quantize and inverse transform the quantized transform coefficients to produce a residual block (378). Video decoder 300 may ultimately decode the current block by combining the prediction block and the residual block (380).
  • entropy encoded data for the current block such as entrop
  • FIG. 13 is a flowchart illustrating an example method for coding (encoding or decoding) video data using pose information according to the techniques of this disclosure.
  • the method of FIG. 13 is explained with respect to warping unit 450 of FIG. 7.
  • warping units 232 or 322 of FIG. 1 may be configured to perform a method similar to that of FIG. 13.
  • the steps involving foveating and defoviating the reference frame need not necessarily be performed in all examples.
  • Warping unit 450 may warp the reference frame between steps 366 and 368 of the method of FIG. 12.
  • warping unit 450 receives pose information for a reference frame (460).
  • the reference frame may be a previously decoded reference frame currently stored in DPB 314.
  • the pose information may include data representing a pose of a user at the time for which the reference frame was generated.
  • Warping unit 450 also receives pose information for a current frame (462).
  • the pose information may include data representing a pose of the user at tire time for which the current frame was generated.
  • Warping unit 450 also recei ves the reference frame itself (464).
  • Warping unit 450 may then determine differences between the pose information for the reference frame and the current frame (466). For example, warping unit 450 may determine whether the user’s head has changed in physical location, orientation, and/or viewing direction. Sensors associated -with a HUD worn by the user may detect, for example, whether the HUD has been moved up, down, left, right, forward, or backward, whether the HUD has changed in pitch, whether the HUD has changed in yaw, and/or whether the HUD has changed in roll.
  • warping unit 450 may initially defoviate the reference frame (468). Warping unit 450 may then warp the defoviated reference frame according to the pose differences (470). Such warping may account for the various changes in the user’s pose between the time for which the reference frame was generated and the time for which the current frame was generated. After warping the reference frame, warping unit 450 may refoviate the warped reference frame (472) to generate the warped reference frame. In examples in which the frames are not foviated, elements 468 and 472 may be omitted.
  • warping unit 450 may provide the warped reference frame to the video coder (474), e.g., video encoder 200 or video decoder 300.
  • FIGS. 11—13 represent an example of a method including determining, by a video coder of a device, pose information representing a current pose of a user of the client device associated with a current picture and a previous pose of the user of the client device associated with a reference picture; ob taining, by the video coder, a warped version of the reference picture according to differences between the current pose and the previous pose; and coding, by the video coder, one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 1 A method of coding video data, the method compri sing: determining, by a video coder of a device, pose information representing poses of a user of the client device associated with a current picture and a reference picture; obtaining, by the video coder, a warped version of the reference picture according to differences between the poses associated with the current picture and the reference picture; and coding, by the video coder, one or more blocks of the current picture using the w arped version of the reference picture.
  • Clause 2 The method of clause 1, wherein obtaining the warped version of the reference picture comprises: sending the reference picture and the pose information to a warping unit of the device; and receiving the warped version of the reference picture from the warping unit.
  • Clause 3 The method of clause 1 , wherein obtaining the warped version of the reference picture comprises warping, by the video coder, the reference picture using the pose information.
  • Clause 4 The method of any of clauses 1-3, wherein the warped reference picture is warped using ahomography matrix computed from the differences between the poses associated with the current picture and the reference picture.
  • Clause 5 The method of any of clauses 1-4, wherein coding tire one or more blocks of the current picture comprises coding a reference picture index identifying the warped reference picture in a reference picture list.
  • Clause 6 The method of any of clauses 1-5, wherein coding the one or more blocks of the current picture comprises: determining a base motion vector from global motion according to the pose information; and coding a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • Clause 7 The method of any of clauses 1-6, wherein coding tire one or more blocks comprises selecting the reference picture as a reference picture having a smallest pose difference in a set of reference pictures relative to the current picture.
  • Clause 8 The method of any of clauses 1-7, wherein coding comprises encoding, the method further comprising seeding a motion estimation process using the pose information.
  • Clause 9 A method of encoding video data, the method comprising: determining a base motion vector according to global motion between a cun-ent picture and a reference picture according to pose information for the current picture and the reference picture; initializing a motion search for a current block of the current picture using the base motion vector; performing the motion search for the current block to determine a block-specific motion vector for the current block; and encoding the current block using the block-specific motion vector.
  • Clause 10 A device for coding video data, the device comprising one or more means for performing the method of any of clauses 1-9.
  • Clause 11 The device of clause 10, wherein the one or more means comprise one or more processors implemented in circuitry.
  • Clause 12 The device of clause 10, further comprising a display configured to display the video data.
  • Clause 13 The device of clause 10, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.
  • Clause 14 The device of clause 10, further comprising a memory configured to store tlie video data.
  • Clause 15 A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to perform the method of any of clauses 1-9.
  • a method of coding video data comprising: determining, by a video coder of a device, pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; obtaining, by the video coder, a warped version of the reference picture according to differences between the current pose and the previous pose; and coding, by the video coder, one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 17 The method of clause 16, w herein obtaining the warped version of the reference picture comprises: sending the reference picture and data of the pose information representing the previous pose to a warping unit of the device, the warping unit being different than the video coder; and receiving the warped version of the reference picture from the warping unit.
  • Clause 18 The method of clause 16, wherein the reference picture comprises one reference picture of a plurality of reference pictures, wherein the pose information represents previous poses of the user of the device associated with each of the plurality' of reference pictures, wherein obtaining the warped version comprises obtaining waiped versions of each of the plurality of reference pictures, and wherein coding the one or more blocks comprises coding the one or more blocks of the current picture using the warped versions of each of the plurality of reference pictures.
  • Clause 20 The method of clause 16, wherein the reference picture comprises a foveated reference picture, and wherein obtaining the warped version of the reference picture comprises: defoveatmg the foveated reference picture to form an expanded reference pictore; wasping the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveating the warped expanded reference picture to produce the w'arped version of the reference picture.
  • the pose information further includes eye position information for the current picture and eye pose information for the reference picture, the eye pose information for the current picture indicating a position of an eye of the user in the current picture, the eye pose information for the reference picture indicating a position of the eye of the user in the reference picture, wherein defoviating the foveated reference picture comprises defoviating the foveated reference picture according to the eye pose information of the reference picture, and wherein foveating the warped expanded reference picture comprises foveating the warped expanded reference picture according to the eye pose information for the current picture.
  • Clause 22 The method of clause 16, further comprising obtaining depth information representing a render depth of the current picture and a render depth of the reference picture, wherein obtaining the waiped version of the reference picture further comprises obtaining the warped version of the reference picture according to differences between the render depth of tire current picture and tire render depth of the reference picture.
  • Clause 23 The method of clause 16, wherein the warped reference picture is warped using a homography matrix computed from the differences between the current pose of the user of the device associated with the current picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 24 The method of clause 16, wherein coding the one or more blocks of the current picture comprises coding a reference picture index identifying the warped reference picture in a reference picture list.
  • Clause 26 The method of clause 16, wherein coding the one or more blocks comprises selecting the reference picture as a reference picture having a smallest pose difference in a set of reference pictures relative to the current picture.
  • Clause 2.7 The method of clause 16, wherein coding comprises encoding, the method further comprising seeding a motion estimation process using the pose information.
  • a device for coding video data comprising: a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine pose information representing a current pose of a user of the device associated with a current picture of the video data and a previous pose of the user of the de vice associated with a reference picture of the video data; obtain a warped version of the reference picture according to differences between the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 29 The device of clause 28, further comprising a warping unit, wherein to obtain the warped version of the reference picture, the one or more processors are configured to: send the reference picture and data of the pose information representing the previous pose to the warping unit of the device; and receive the warped version of the reference picture from the warping unit.
  • Clause 30 The device of clause 28, wherein to obtain the warped version of the reference picture, the one or more processors are configured to warp the reference picture using the pose information.
  • Clause 31 The device of clause 28, wherein the reference picture comprises a foveated reference picture, and wherein to obtain the warped version of the reference picture, the one or more processors are configured to: defoveate the foveated reference picture to form an expanded reference picture; wasp the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveate the warped expanded reference picture to produce the warped version of the reference picture.
  • Clause 32 The device of clause 28, wherein the warped reference picture is warped using a homography matrix computed from the differences between the current pose of the user of the device associated with the current picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 33 The device of clause 28, wherein to code the one or more blocks of the current picture, the one or more processors are configured to code a reference picture index identifying the warped reference picture in a reference picture list.
  • Clause 34 The device of clause 28, wherein to code the one or more blocks of the current picture, the one or more processors are configured to: determine a base motion vector from global motion according to the pose information; and code a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • Clause 35 The device of clause 28, wh erein to code the one or more blocks, the one or more processors are configured to select the reference picture as a reference picture having a smallest pose difference in a set of reference pictures relative to the current picture.
  • Clause 36 The device of clause 28, wherein to code the one or more blocks, the one or more processors are configured to encode the one or more blocks, and wherein the one or more processors are further configured to seed a motion estimation process using the pose information.
  • Clause 37 The device of clause 28, further comprising a display configured to display the video data.
  • Clause 38 The device of clause 28, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.
  • Clause 39 A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device to: determine pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data.; obtain a warped version of the reference picture according to differences between the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 40 The computer-readable storage medium of clause 39, wherein the instructions that cause the processor to obtain the warped version of the reference picture comprise instructions that cause the processor to: send the reference picture and data of the pose information representing the previous pose to a warping unit; and receive the warped version of the reference picture from the warping unit.
  • Clause 42 The computer-readable storage medium of clause 39, wherein the reference picture comprises a foveated reference picture, and wherein the instructions that cause the processor to obtain the warped version of the reference picture comprise instructions that cause the processor to: defoveate the foveated reference picture to form an expanded reference picture; warp the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveate the warped expanded reference picture to produce the warped version of the reference picture.
  • Clause 43 The computer-readable storage medium of clause 39, wherein the warped reference picture is warped using a homography matrix computed from the differences between the current pose of the user of the device associated with the cun-ent picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 44 The computer-readable storage medium of clause 39, wherein the instructions that cause the processor to code the one or more blocks of the cun-ent picture comprise instructions that cause the processor to: determine a base motion vector from global motion according to the pose information; and code a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • a device for coding video data comprising: means for determining pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; means for obtaining a warped version of tire reference picture according to differences between the current pose and the previous pose; and means for coding one or more blocks of the current picture using the warped version of the reference picture.
  • a method of coding video data comprising: determining, by a video coder of a device, pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the de vice associated w ith a reference picture of the video data; obtaining, by the video coder, a warped version of the reference picture according to differences between the current pose and the previous pose; and coding, by the video coder, one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 47 The method of clause 46, wherein obtaining the warped version of the reference picture comprises: sending the reference picture and data of the pose information representing the previous pose to a warping unit of the device, the warping unit being different than tire video coder; and receiving the warped version of the reference picture from the warping unit.
  • Clause 48 The method of clause 46, wherein obtaining the warped version of the reference picture comprises warping, by the video coder, the reference picture using the pose information,
  • Clause 49 The method of any of clauses 46-48, wherein the reference picture comprises one reference picture of a plurality of reference pictures, wherein the pose information represents previous poses of the user of the device associated with each of the plurality of reference pictures, wherein obtaining the warped version comprises obtaining warped versions of each of the plurality of reference pictures, and wherein coding the one or more blocks comprises coding the one or more blocks of the current picture using the warped versions of each of the plurality of reference pictures.
  • Clause 50 The method of any of clauses 46-49, wherein the reference picture comprises a foveated reference picture, and w herein obtaining the warped version of the reference picture comprises: defoveating the foveated reference picture to form an expanded reference picture; warping the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveating the warped expanded reference picture to produce the warped version of the reference picture.
  • the pose information further includes eye position information for the current picture and eye pose information for the reference picture, the eye pose information for the current picture indicating a position of an eye of the user in the current picture, the eye pose information for the reference picture indicating a position of the eye of the user in the reference picture, wherein defoviating the foveated reference picture comprises defoliating the foveated reference picture according to the eye pose information of the reference picture, and wherein foveating the warped expanded reference picture comprises foveating the warped expanded reference picture according to the eye pose information for tire current picture.
  • Clause 52 The method of any of clauses 46-51 , further comprising obtaining depth information representing a render dep th of the current picture and a render depth of the reference picture, wherein obtaining the w arped version of tire reference picture further comprises obtaining the warped version of the reference picture according to differences betw een the render depth of the current picture and the render depth of the reference picture.
  • Clause 53 The method of any of clauses 46-52, wherein the warped reference picture is warped using a homography matrix computed from the differences between the current pose of the user of the device associated with the current picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 54 The method of any of clauses 46-53, wherein coding the one or more blocks of the current picture comprises coding a reference picture index identifying the warped reference picture in a reference picture list.
  • Clause 55 The method of any of clauses 46-54, wherein coding tire one or more blocks of the current picture comprises: determining a base motion vector from global motion according to the pose information; and coding a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • Clause 56 The method of any of clauses 46- 55, wherein coding the one or more blocks comprises selecting the reference picture as a reference picture having a smallest pose difference in a set of reference pictures relative to the current picture.
  • Clause 57 The method of any of clauses 46-56, wherein coding comprises encoding, the method further comprising seeding a motion estimation process using the pose information.
  • a device for coding video data comprising: a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine pose information representing a current pose of a user of the device associated with a current picture of the video data and a previous pose of the user of the de vice associated w ith a reference picture of the video data; obtain a warped version of the reference picture according to differences between the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 59 The device of clause 58, further comprising a warping unit, wherein to obtain the warped version of the reference picture, the one or more processors are configured to: send the reference picture and data of the pose information representing the previous pose to the warping unit of the device; and receive the warped version of the reference picture from the warping unit.
  • Clause 60 The device of clause 58, wherein to obtain the warped version of the reference picture, the one or more processors are configured to warp the reference picture using the pose information.
  • Clause 61 The device of any of clauses 58-60, wherein the reference picture comprises a foveated reference picture, and wherein to obtain the warped version of the reference picture, the one or more processors are configured to: defoveate the foveated reference picture to form an expanded reference picture; warp the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveate the warped expanded reference picture to produce the warped version of the reference picture.
  • Clause 62 The device of any of clauses 58-61, wherein the warped reference picture is warped using ahomography matrix computed from the differences between the current pose of the user of the device associated with the current picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 63 The device of any of clauses 58-62, wherein to code the one or more blocks of the current picture, the one or more processors are configured to code a reference picture index identifying the warped reference picture in a reference picture list.
  • Clause 64 The device of any of clauses 58-63, wherein to code the one or more blocks of the current picture, the one or more processors are configured to: determine a base motion vector from global motion according to the pose information; and code a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • Clause 65 The device of any of clauses 58-64, wherein to code the one or more blocks, the one or more processors are configured to select the reference picture as a reference picture having a smallest pose difference in a set of reference pictures relative to the current picture.
  • Clause 66 The device of any of clauses 58-65, wherein to code the one or more blocks, the one or more processors are configured to encode the one or more blocks, and wherein the one or more processors are further configured to seed a motion estimation process using the pose information.
  • Clause 67 The device of any of clauses 58-66, further comprising a display configured to display the video data.
  • Clause 68 The device of any of clauses 58-67, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.
  • a computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device to: determine pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; obtain a warped version of the reference picture according to differences between the current pose and the previous pose; and code one or more blocks of the current picture using the warped version of the reference picture.
  • Clause 70 The computer-readable storage medium of clause 69, wherein the instructions that cause the processor to obtain the warped version of tire reference picture comprise instructions that cause the processor to: send the reference picture and data of the pose information representing the previous pose to a warping unit; and receive the w arped version of the reference picture from the warping unit.
  • Clause 71 The computer-readable storage medium of clause 69, wherein the instructions that cause the processor to obtain the warped version of the reference picture comprise instructions that cause the processor to warp the reference picture using the pose information.
  • Clause 72 The computer-readable storage medium of any of clauses 69-71, wherein the reference picture comprises a foveated reference picture, and wherein the instructions that cause the processor to obtain the warped version of the reference picture comprise instructions that cause the processor to: defoveate the foveated reference picture to form an expanded reference picture; warp the expanded reference picture to form a warped expanded reference picture according to the pose information; and foveate the warped expanded reference picture to produce the warped version of the reference picture.
  • Clause 73 The computer-readable storage medium of any of clauses 69-72, wherein the warped reference picture is warped using a homography matrix computed from the differences between the current pose of the user of the device associated with the current picture and the previous pose of the user of the device associated with the reference picture.
  • Clause 74 The computer-readable storage medium of any of clauses 69-73, wherein the instructions that cause the processor to code the one or more blocks of the current picture comprise instructions that cause the processor to: determine a base motion vector from global motion according to the pose information; and code a motion vector of one of the one or more blocks using the base motion vector as a motion vector predictor.
  • a device for coding video data comprising: means for determining pose information representing a current pose of a user of the device associated with a current picture of video data and a previous pose of the user of the device associated with a reference picture of the video data; means for obtaining a warped version of the reference picture according to differences between the current pose and the previous pose; and means for coding one or more blocks of the current picture using the warped version of the reference picture.
  • Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media, or communication media including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol.
  • computer- readable media generally may correspond to (1) tangible computer-readable storage media which is non-transitory 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 implementation of the techniques described in this disclosure.
  • a computer program product may include a computer-readable medium.
  • 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. Also, any connection is properly termed a computer-readable medium.
  • 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 w ireless technologies such as infrared, radio, and microwave are included in the definition of medium.
  • coaxial cable, fiber optic cable, twisted pair, DSL, or w ireless technologies such as infrared, radio, and microwave are included in the definition of medium.
  • computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory, tangible storage media.
  • Disk and disc 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.
  • processors such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry.
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • processors may refer to any of the foregoing structures or any other structure suitable tor implementation of the techniques described herein.
  • the functionality described herein may be provided within dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combined codec. Also, the techniques could 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 chip set).
  • IC integrated circuit
  • 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 described above, various units may be combined in a codec hardware unit or provided by a collection of interoperati ve hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware, [0240]
  • Various examples have been described. These and oilier examples are within the scope of the following claims.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L'invention concerne un dispositif client de réalité virtuelle (VR) pouvant être configuré pour agir en tant que partie d'un système de rendu divisé. Le dispositif client VR peut comprendre une mémoire configurée pour stocker des données vidéo et un ou plusieurs processeurs mis en œuvre dans des circuits et configurés pour : déterminer des informations de pose représentant une pose actuelle d'un utilisateur du dispositif associé à une image actuelle des données vidéo et une pose précédente de l'utilisateur du dispositif associé à une image de référence des données vidéo ; obtenir une version déformée de l'image de référence selon les différences entre la pose actuelle et la pose précédente ; et coder un ou plusieurs blocs de l'image actuelle en utilisant la version déformée de l'image de référence.
PCT/US2021/051997 2020-10-01 2021-09-24 Codage de données vidéo à l'aide d'informations de pose d'un utilisateur WO2022072242A1 (fr)

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WO2024010606A1 (fr) * 2022-07-06 2024-01-11 Tencent America LLC Améliorations apportées à des modes de prédiction de mouvement de déformation locale
CN115086678A (zh) * 2022-08-22 2022-09-20 北京达佳互联信息技术有限公司 视频编码方法和装置、视频解码方法和装置

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