WO2020251418A2 - Procédé et appareil de signalisation de niveau de tranche pour affinement de vecteur de mouvement latéral de décodeur et de flux optique bidirectionnel - Google Patents

Procédé et appareil de signalisation de niveau de tranche pour affinement de vecteur de mouvement latéral de décodeur et de flux optique bidirectionnel Download PDF

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WO2020251418A2
WO2020251418A2 PCT/RU2020/050261 RU2020050261W WO2020251418A2 WO 2020251418 A2 WO2020251418 A2 WO 2020251418A2 RU 2020050261 W RU2020050261 W RU 2020050261W WO 2020251418 A2 WO2020251418 A2 WO 2020251418A2
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Prior art keywords
prediction
slice
motion refinement
video coding
block
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PCT/RU2020/050261
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English (en)
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WO2020251418A3 (fr
Inventor
Alexey Konstantinovich FILIPPOV
Vasily Alexeevich RUFITSKIY
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Huawei Technologies Co., Ltd.
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Publication of WO2020251418A2 publication Critical patent/WO2020251418A2/fr
Publication of WO2020251418A3 publication Critical patent/WO2020251418A3/fr

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  • Embodiments of the present application generally relate to the field of video coding and more particularly to signaling of slice header syntax elements.
  • Video coding (video encoding and decoding) is used in a wide range of digital video applications, for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications.
  • digital video applications for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications.
  • Video compression devices often use software and/or hardware at the source to code the video data prior to transmission or storage, thereby decreasing the quantity of data needed to represent digital video images.
  • the compressed data is then received at the destination by a video decompression device that decodes the video data.
  • Embodiments provide methods for encoding and decoding a video sequence comprising coding of slice header syntax elements that depend on slice type.
  • Embodiments provide for an efficient encoding and/or decoding and corresponding signalling using non-rectangular subblock partitioning and prediction modes like TPM, GEO or GPM and signal related information in slice headers only for slices which allow or enable bidirectional inter-prediction, e.g. in bidirectional (B) prediction slices, also called B-slices.
  • B bidirectional
  • a method for encoding a video sequence using one or more motion refinement video coding tools for bi-directional prediction comprises:
  • this method is only performed if the slice type indicates a B-slice type in the usually used nomenclature.
  • the method according to this embodiment allows for providing information on which of the motion refinement video coding tools to use, where this information is provided in a bitstream, freeing the decoder from having to making computationally expensive evaluations of the encoded data to determine which motion refinement video coding tools to use.
  • a method for decoding an encoded video sequence using one or more motion refinement video coding tools for bi-directional prediction is provided, wherein the method comprises:
  • decoding the at least one block of the video sequence by decoding the at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction.
  • This method reduces the computational complexity of the decoding because the information necessary to decide for which motion refinement video coding tools to use is already provided in, for example, a bitstream sent separate to the encoded video sequence or in the encoded video sequence itself.
  • This information is (for example only 1 bit), the less processing is necessary for obtaining the respective information at the decoder and the smaller the datastream which comprises or constitutes the encoded video sequence can be.
  • the slice-level information related to the one or more motion refinement video coding tools for bi-directional prediction is signaled only for B-slices.
  • the slice-level information related to the one or more motion refinement video coding tools for bi-directional prediction is inferred to be equal to values that disable said one or more motion refinement video coding tools when it is not signaled for B- slices.
  • the method comprises:
  • SPS sequence parameter set
  • the one or more motion refinement video coding tool for bi-directional prediction comprise or is BDOF.
  • the one or more motion refinement video coding tool for bi-directional prediction comprise or is DMVR.
  • the slice-level information is included in a bitstream.
  • This bitstream can either be separate from the encoded video sequence, for example a completely separate bitstream, or it can form part of a bitstream that also comprises the encoded video sequence.
  • the bitstream comprising the encoded video sequence may be called a datastream. This embodiment makes available the information on the motion refinement video coding tool to the encoder in an efficient way.
  • the slice-level information may be included in a header of the bitstream. This allows to obtain the information by parsing the header before processing the bitstream at all. Furthermore, such information can be included by the header efficiently, reducing the size of the encoded video sequence.
  • bitstream is or comprises the encoded video sequence.
  • the slice-level information indicates the one or more motion refinement tools to be used in the prediction.
  • the slice-level information is or comprises information (for example in the form of a flag) that allows, either without processing or with comparably little further processing of this information, to determine the one or more motion refinement tools to be used in the prediction.
  • the slice-level information comprises a flag indicating the one or more motion refinement tools to be used in the prediction.
  • the slice-level information may not only comprise the flag (and potentially additional information).
  • the slice-level information is the flag.
  • Flags can be provided for example in headers of files or, in this case, in a header of a slice with reduced size. Thereby, the size of the encoded video sequence can be reduced further. More specifically, the size of the flag may be 1 bit. This information is the smallest possible amount for encoding the respective slice-level information for the one or more motion refinement video coding tools, reducing the size of the encoded video sequence even further. Though providing the information with this flag may cause further processing at the decoder for actually obtaining knowledge on which motion refinement video coding tools to use, the amount of data that needs to be processed is reduced thereby to a minimum.
  • the one or more motion refinement video coding tools for bi-directional prediction comprise or are at least one of BDOF and DMVR.
  • an encoder comprising processing circuitry configured for performing the method according to any of the above embodiments. This implements the advantages of the above methods when encoding video sequences.
  • a decoder comprising processing circuitry configured for performing the method according to any of the above embodiments. This implements the advantages of the above methods when decoding encoded video sequences.
  • a encoder comprising one or more processors; and a non-transitory storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out the method according to any one of the above embodiments.
  • a decoder comprising one or more processors; and a non-transitory storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the decoder to carry out the method according to any of the above embodiments.
  • a program product comprising a program code for performing the method according to any of the above embodiments is provided.
  • a non-transitory medium carrying a program code which, when executed by a device, causes the device to perform the method of any of the above embodiments is provided.
  • an encoder for encoding a video sequence using one or more motion refinement video coding tools for bi-directional prediction is provided, the encoder comprising:
  • the prediction unit is adapted to:
  • the encoding unit is adapted to:
  • a decoder for decoding an encoded video sequence using one or more motion refinement video coding tools for bi-directional prediction comprising:
  • a receiving unit
  • a decoding unit
  • the receiving unit is adapted to:
  • the decoding unit is adapted to:
  • This decoder can decode an encoded video sequence efficiently with less computational efforts.
  • a method for encoding a video sequence e.g. a coded video sequence, CVS
  • CVS coded video sequence
  • a type of a slice (slice type) of the video sequence (to be encoded) allows bi-directional inter-prediction (e.g. is a bi-directional inter-prediction slice or B-slice),
  • block-level e.g. coding block (CB)
  • CU coding unit
  • - encoding the video by encoding at least one block predicted using motion refinement video coding tools for bi-directional prediction (e.g. by obtaining a residual for this block and the predictor obtained from the inter-prediction, and transformation and quantization of the residual);
  • This method advantageously reduces the size of the encoded video sequence.
  • a method for decoding a video sequence e.g. a coded video sequence, CVS
  • a method for decoding a video sequence e.g. a coded video sequence, CVS
  • the method comprises:
  • block-level e.g. coding block (CB) level or coding unit (CU) level
  • CB coding block
  • CU coding unit
  • the slice level information related to motion refinement video coding tools for bi-directional prediction e.g. a flag slice_disable_bdof_dmvr_flag
  • a flag slice_disable_bdof_dmvr_flag is signaled only for B-slices. This reduces the size of the encoded video sequence further in case the encoded video sequence does not only comprise B-slices.
  • the slice level information related to motion refinement video coding tools for bi-directional prediction e.g. a flag slice_disable_bdof_dmvr_flag
  • a flag slice_disable_bdof_dmvr_flag is inferred to be equal to values that disables said motion refinement video coding tools when it is not signaled for B-slices.
  • the method comprises:
  • SPS sequence parameter set
  • sps_bdof_dmvr_slice_present_flag sequence parameter set
  • the motion refinement video coding tool for bi-directional prediction comprises or is BDOF.
  • the motion refinement video coding tool for bi-directional prediction comprises or is DMVR.
  • the motion refinement video coding tools for bi-directional prediction comprise or are at least one of BDOF and DMVR.
  • An encoder comprising processing circuitry (e.g. a processor) configured for performing the method according to any one of any of the above embodiments is provided according to a further embodiment. This implements the advantages of the above methods when encoding video sequences.
  • a decoder comprising processing circuitry (e.g. a processor) configured for performing the method according to any one of the above embodiments is provided. This implements the advantages of the above methods when decoding encoded video sequences.
  • an encoder comprising one or more processors; and a non-transitory storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out the method according to any one the above embodiments.
  • a decoder may be provided, the decoder comprising one or more processors; and a non-transitory storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out the method according to any one of the above embodiments.
  • a program product comprising a program code for performing the method according to any one of the above embodiments is provided.
  • non-transitory medium carrying a program code which, when executed by a device, causes the device to perform the method of any one of the above embodiments may be provided.
  • FIG. 1 A is a block diagram showing an example of a video coding system configured to implement embodiments of the invention
  • FIG. 1 B is a block diagram showing another example of a video coding system configured to implement embodiments of the invention
  • FIG. 2 is a block diagram showing an example of a video encoder configured to
  • FIG. 3 is a block diagram showing an example structure of a video decoder configured to implement embodiments of the invention
  • FIG. 4 is a block diagram illustrating an example of an encoding apparatus or a decoding apparatus
  • FIG. 5 is a block diagram illustrating another example of an encoding apparatus or a decoding apparatus
  • FIG. 6 is an illustration of the steps required at encoder side to obtain a set of transform blocks for used color components marked as a transform unit according to an embodiment of the invention
  • FIG. 7 is an illustration of an alternative way to resample residual blocks for obtaining a set of transform blocks for used color components marked as a transform unit according to an embodiment of the invention
  • FIG. 8 is a flowchart to illustrate the processing steps of the invention applied to a unit predicted using TPM at both decoder and encoder sides according to an embodiment of the invention
  • FIG. 9 is an illustration of a resampling process within a unit where the GMP technique is used according to an embodiment of the invention.
  • FIG. 10 is a flowchart to illustrate the processing steps of an embodiment of the invention at both decoder and encoder side if the resampling process is applied to a unit where the GMP technique is used;
  • FIG. 11 is a flowchart showing the signaling of the flag according to an embodiment of the invention.
  • FIG. 12 is a flowchart showing the signaling of the flag according to an embodiment of the invention
  • FIG. 13 is an illustration of the smoothing process that uses one-dimensional padding of the samples adjacent to the near-boundary region;
  • FIG. 14 is an illustration of the smoothing process that uses two-dimensional spatial filter of the samples adjacent to the near-boundary region
  • FIG. 15 is an illustration of obtaining the near-boundary region for the case of GMP using column-wise scan
  • FIG. 16 is an illustration of obtaining the near-boundary region for the case of GMP using a row-wise scan
  • FIG. 17 is an illustration of obtaining the near-boundary region for the case of GEO using a row-wise scan
  • FIG. 18 shows TPM and GEO modes
  • FIG. 19 shows parameters related to GEO
  • FIG. 20 illustrates a process of bi-directional optical flow (BDOF).
  • FIG. 21 illustrates a process of decoder side motion vector refinement (DMVR).
  • FIG. 22 shows a flow diagram of an embodiment of a method for encoding a video
  • FIG. 23 shows a flow diagram of an embodiment of a method for decoding a video
  • FIG. 24 shows a block diagram of an encoder according to one embodiment
  • FIG. 25 shows a block diagram of a decoder according to one embodiment.
  • a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa.
  • a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures.
  • a specific apparatus is described based on one or a plurality of units, e.g.
  • a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.
  • Video coding typically refers to the processing of a sequence of pictures, which form the video or video sequence. Instead of the term“picture” the term“frame” or“image” may be used as synonyms in the field of video coding.
  • Video coding (or coding in general) comprises two parts video encoding and video decoding. Video encoding is performed at the source side, typically comprising processing (e.g. by compression) the original video pictures to reduce the amount of data required for representing the video pictures (for more efficient storage and/or transmission). Video decoding is performed at the destination side and typically comprises the inverse processing compared to the encoder to reconstruct the video pictures.
  • Embodiments referring to“coding” of video pictures shall be understood to relate to“encoding” or“decoding” of video pictures or respective video sequences.
  • the combination of the encoding part and the decoding part is also referred to as CODEC (Coding and Decoding).
  • the original video pictures can be reconstructed, i.e. the reconstructed video pictures have the same quality as the original video pictures (assuming no transmission loss or other data loss during storage or transmission).
  • further compression e.g. by quantization, is performed, to reduce the amount of data representing the video pictures, which cannot be completely reconstructed at the decoder, i.e. the quality of the reconstructed video pictures is lower or worse compared to the quality of the original video pictures.
  • Video coding standards belong to the group of“lossy hybrid video codecs” (i.e. combine spatial and temporal prediction in the sample domain and 2D transform coding for applying quantization in the transform domain).
  • Each picture of a video sequence is typically partitioned into a set of non-overlapping blocks and the coding is typically performed on a block level.
  • the video is typically processed, i.e. encoded, on a block (video block) level, e.g.
  • the encoder duplicates the decoder processing loop such that both will generate identical predictions (e.g. intra- and inter predictions) and/or re-constructions for processing, i.e. coding, the subsequent blocks.
  • a video encoder 20 and a video decoder 30 are described based on Figs. 1 to 3.
  • Fig. 1A is a schematic block diagram illustrating an example coding system 10, e.g. a video coding system 10 (or short coding system 10) that may utilize techniques of this present application.
  • Video encoder 20 (or short encoder 20) and video decoder 30 (or short decoder 30) of video coding system 10 represent examples of devices that may be configured to perform techniques in accordance with various examples described in the present application.
  • the coding system 10 may comprise a source device 12 configured to provide encoded picture data 21 e.g. to a destination device 14 for decoding the encoded picture data 13.
  • the source device 12 may comprise an encoder 20, and may additionally, i.e. optionally, comprise a picture source 16, a pre-processor (or pre-processing unit) 18, e.g. a picture preprocessor 18, and a communication interface or communication unit 22.
  • a pre-processor or pre-processing unit 18
  • a communication interface or communication unit 22 e.g. a communication interface or communication unit 22.
  • the picture source 16 may comprise or be any kind of picture capturing device, for example a camera for capturing a real-world picture, and/or any kind of a picture generating device, for example a computer-graphics processor for generating a computer animated picture, or any kind of other device for obtaining and/or providing a real-world picture, a computer generated picture (e.g. a screen content, a virtual reality (VR) picture) and/or any combination thereof (e.g. an augmented reality (AR) picture).
  • the picture source may be any kind of memory or storage storing any of the aforementioned pictures.
  • the picture or picture data 17 may also be referred to as raw picture or raw picture data 17.
  • Pre-processor 18 is configured to receive the (raw) picture data 17 and to perform preprocessing on the picture data 17 to obtain a pre-processed picture 19 or pre-processed picture data 19.
  • Pre-processing performed by the pre-processor 18 may, e.g., comprise trimming, color format conversion (e.g. from RGB to YCbCr), color correction, or de-noising. It can be understood that the pre-processing unit 18 may be optional component.
  • the video encoder 20 may be configured to receive the pre-processed picture data 19 and provide encoded picture data 21 (further details will be described below, e.g., based on Fig. 2).
  • Communication interface 22 of the source device 12 may be configured to receive the encoded picture data 21 and to transmit the encoded picture data 21 (or any further processed version thereof) over communication channel 13 to another device, e.g. the destination device 14 or any other device, for storage or direct reconstruction.
  • the destination device 14 may comprise a decoder 30 (e.g. a video decoder 30), and may additionally, i.e. optionally, comprise a communication interface or communication unit 28, a post-processor 32 (or post-processing unit 32) and a display device 34.
  • a decoder 30 e.g. a video decoder 30
  • the communication interface 28 of the destination device 14 may be configured receive the encoded picture data 21 (or any further processed version thereof), e.g. directly from the source device 12 or from any other source, e.g. a storage device, e.g. an encoded picture data storage device, and provide the encoded picture data 21 to the decoder 30.
  • a storage device e.g. an encoded picture data storage device
  • the communication interface 22 and the communication interface 28 may be configured to transmit or receive the encoded picture data 21 or encoded data 13 via a direct
  • the communication interface 22 may be, e.g., configured to package the encoded picture data 21 into an appropriate format, e.g. packets, and/or process the encoded picture data using any kind of transmission encoding or processing for transmission over a
  • the communication interface 28, forming the counterpart of the communication interface 22, may be, e.g., configured to receive the transmitted data and process the transmission data using any kind of corresponding transmission decoding or processing and/or de-packaging to obtain the encoded picture data 21.
  • Both, communication interface 22 and communication interface 28 may be configured as unidirectional communication interfaces as indicated by the arrow for the communication channel 13 in Fig. 1A pointing from the source device 12 to the destination device 14, or bidirectional communication interfaces, and may be configured, e.g. to send and receive messages, e.g. to set up a connection, to acknowledge and exchange any other information related to the communication link and/or data transmission, e.g. encoded picture data transmission.
  • the decoder 30 may be configured to receive the encoded picture data 21 and provide decoded picture data 31 or a decoded picture 31 (further details will be described below, e.g., based on Fig. 3 or Fig. 5).
  • the post-processor 32 of destination device 14 may be configured to post-process the decoded picture data 31 (also called reconstructed picture data), e.g. the decoded picture 31 , to obtain post-processed picture data 33, e.g. a post-processed picture 33.
  • the postprocessing performed by the post-processing unit 32 may comprise, e.g. color format conversion (e.g. from YCbCr to RGB), color correction, trimming, or re-sampling, or any other processing, e.g. for preparing the decoded picture data 31 for display, e.g. by display device 34.
  • the display device 34 of the destination device 14 may be configured to receive the post- processed picture data 33 for displaying the picture, e.g. to a user or viewer.
  • the display device 34 may be or comprise any kind of display for representing the reconstructed picture, e.g. an integrated or external display or monitor.
  • the displays may, e.g. comprise liquid crystal displays (LCD), organic light emitting diodes (OLED) displays, plasma displays, projectors , micro LED displays, liquid crystal on silicon (LCoS), digital light processor (DLP) or any kind of other display.
  • LCD liquid crystal displays
  • OLED organic light emitting diodes
  • LCDoS liquid crystal on silicon
  • DLP digital light processor
  • Fig. 1A depicts the source device 12 and the destination device 14 as separate devices, embodiments of devices may also comprise both or both functionalities, the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality. In such embodiments the source device 12 or corresponding functionality and the destination device 14 or corresponding functionality may be implemented using the same
  • the encoder 20 e.g. a video encoder 20
  • the decoder 30 e.g. a video decoder 30
  • both encoder 20 and decoder 30 may be implemented via processing circuitry as shown in Fig. 1 B, such as one or more microprocessors, digital signal processors (DSPs), application- specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, video coding dedicated or any combinations thereof.
  • the encoder 20 may be implemented via processing circuitry 46 to embody the various modules as discussed with respect to encoder 20of FIG. 2 and/or any other encoder system or subsystem described herein.
  • the decoder 30 may be implemented via processing circuitry 46 to embody the various modules as discussed with respect to decoder 30 of FIG. 3 and/or any other decoder system or subsystem described herein.
  • the processing circuitry may be configured to perform the various operations as discussed later.
  • a device may store instructions for the software in a suitable, non-transitory storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure.
  • Either of video encoder 20 and video decoder 30 may be integrated as part of a combined encoder/decoder (CODEC) in a single device, for example, as shown in Fig. 1 B.
  • CDEC combined encoder/decoder
  • Source device 12 and destination device 14 may comprise any of a wide range of devices, including any kind of handheld or stationary devices, e.g. notebook or laptop computers, mobile phones, smart phones, tablets or tablet computers, cameras, desktop computers, set-top boxes, televisions, display devices, digital media players, video gaming consoles, video streaming devices(such as content services servers or content delivery servers), broadcast receiver device, broadcast transmitter device, or the like and may use no or any kind of operating system.
  • the source device 12 and the destination device 14 may be equipped for wireless communication.
  • the source device 12 and the destination device 14 may be wireless communication devices.
  • video coding system 10 illustrated in Fig. 1A is merely an example and the techniques of the present application may apply to video coding settings (e.g., video encoding or video decoding) that do not necessarily include any data communication between the encoding and decoding devices.
  • data is retrieved from a local memory, streamed over a network, or the like.
  • a video encoding device may encode and store data to memory, and/or a video decoding device may retrieve and decode data from memory.
  • the encoding and decoding is performed by devices that do not communicate with one another, but simply encode data to memory and/or retrieve and decode data from memory.
  • both the encoder 20 and the decoder 30 and associated systems may be implemented by either hardware or software or combinations of the same.
  • the encoder (or the decoder) may be implemented by software only, the software comprising a plurality of software modules that may each be provided to perform specific functionalities of the encoder (or the decoder).
  • the software modules can be provided in a way so as to be able to interact with hardware, like the hardware in a general-purpose computer, like a processor, memory and the like, to realize, when the software modules are executed, the functionality of the encoder (or decoder).
  • the invention is, in this sense, not limited to implementations on specific hardware and/or software.
  • HEVC High-Efficiency Video Coding
  • WC Versatile Video coding
  • JCT-VC Joint Collaboration Team on Video Coding
  • VCEG ITU-T Video Coding Experts Group
  • MPEG ISO/IEC Motion Picture Experts Group
  • Fig. 2 shows a schematic block diagram of an example video encoder 20 that is configured to implement the techniques of the present application.
  • the video encoder 20 comprises an input 201 (or input interface 201 ), a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, and inverse transform processing unit 212, a reconstruction unit 214, a loop filter unit 220, a decoded picture buffer (DPB) 230, a mode selection unit 260, an entropy encoding unit 270 and an output 272 (or output interface 272).
  • the mode selection unit 260 may include an inter prediction unit 244, an intra prediction unit 254 and a partitioning unit 262.
  • Inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown).
  • a video encoder 20 as shown in Fig. 2 may also be referred to as hybrid video encoder or a video encoder according to a hybrid video codec.
  • the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the mode selection unit 260 may be referred to as forming a forward signal path of the encoder 20, whereas the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244 and the intra-prediction unit 254 may be referred to as forming a backward signal path of the video encoder 20, wherein the backward signal path of the video encoder 20 corresponds to the signal path of the decoder (see video decoder 30 in Fig. 3).
  • the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the loop filter 220, the decoded picture buffer (DPB) 230, the inter prediction unit 244 and the intra-prediction unit 254 are also referred to forming the“built-in decoder” of video encoder 20.
  • the encoder 20 may be configured to receive, e.g. via input 201 , a picture 17 (or picture data 17), e.g. picture of a sequence of pictures forming a video or video sequence.
  • the received picture or picture data may also be a pre-processed picture 19 (or pre-processed picture data 19).
  • the picture 17 may also be referred to as current picture or picture to be coded (in particular in video coding to distinguish the current picture from other pictures, e.g. previously encoded and/or decoded pictures of the same video sequence, i.e. the video sequence which also comprises the current picture).
  • a (digital) picture is or can be regarded as a two-dimensional array or matrix of samples with intensity values.
  • This two-dimensional array may have arbitrary size.
  • the array can have a size of an NxM matrix.
  • N, M G N. N may be equal to M, resulting in a square matrix.
  • M 1 N so that a general rectangle is obtained for the two-dimensional array.
  • M and N may take any values.
  • a sample in the array may also be referred to as pixel (short form of picture element) or a pel.
  • the number of samples in horizontal and vertical direction (or axis) of the array or picture define the size and/or resolution of the picture.
  • typically three color components are employed, i.e. the picture may be represented or include three sample arrays.
  • a picture comprises a corresponding red, green and blue sample array.
  • each pixel is typically represented in a luminance
  • chrominance format or color space e.g. YCbCr, which comprises a luminance component indicated by Y (sometimes also L is used instead) and two chrominance components indicated by Cb and Cr.
  • the luminance (or short luma) component Y represents the brightness or grey level intensity (e.g. like in a grey-scale picture), while the two
  • chrominance (or short chroma) components Cb and Cr represent the chromaticity or color information components.
  • a picture in YCbCr format comprises a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (Cb and Cr).
  • Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, the process is also known as color transformation or conversion. If a picture is monochrome, the picture may comprise only a luminance sample array.
  • a picture may be, for example, an array of luma samples in monochrome format or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 colour format.
  • the video encoder may be configured to receive directly a block 203 of the picture 17, e.g. one, several or all blocks forming the picture 17.
  • the picture block 203 may also be referred to as current picture block or picture block to be coded.
  • the picture block 203 again is or can be regarded as a two-dimensional array or matrix of samples with intensity values (sample values), although of smaller dimension than the picture 17.
  • the block 203 may comprise, e.g., one sample array (e.g. a luma array in case of a monochrome picture 17, or a luma or chroma array in case of a color picture) or three sample arrays (e.g. a luma and two chroma arrays in case of a color picture 17) or any other number and/or kind of arrays depending on the color format applied.
  • the number of samples in horizontal and vertical direction (or axis) of the block 203 define the size of block 203.
  • a block may, for example, an MxN (M-column by N-row) array of samples, or an MxN array of transform coefficients.
  • N and M may correspond to N and M referred to above.
  • Embodiments of the video encoder 20 as shown in Fig. 2 may be configured to encode the picture 17 block by block, e.g. the encoding and prediction is performed per block 203.
  • Embodiments of the video encoder 20 as shown in Fig. 2 may be further configured to partition and/or encode the picture by using slices (also referred to as video slices), wherein a picture may be partitioned into or encoded using one or more slices (typically nonoverlapping), and each slice may comprise one or more blocks (e.g. CTUs).
  • slices also referred to as video slices
  • each slice may comprise one or more blocks (e.g. CTUs).
  • Embodiments of the video encoder 20 as shown in Fig. 2 may be further configured to partition and/or encode the picture by using tile groups (also referred to as video tile groups) and/or tiles (also referred to as video tiles), wherein a picture may be partitioned into or encoded using one or more tile groups (typically non-overlapping), and each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g.
  • tile groups also referred to as video tile groups
  • tiles also referred to as video tiles
  • each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g.
  • the residual calculation unit 204 may be configured to calculate a residual block 205 (also referred to as residual 205) based on the picture block 203 and a prediction block 265 (further details about the prediction block 265 are provided later), e.g. by subtracting sample values of the prediction block 265 from sample values of the picture block 203, sample by sample (pixel by pixel) to obtain the residual block 205 in the sample domain.
  • a residual block 205 also referred to as residual 205
  • a prediction block 265 further details about the prediction block 265 are provided later
  • the transform processing unit 206 may be configured to apply a transform, e.g. a discrete cosine transform (DCT) or discrete sine transform (DST), on the sample values of the residual block 205 to obtain transform coefficients 207 in a transform domain.
  • a transform e.g. a discrete cosine transform (DCT) or discrete sine transform (DST)
  • DCT discrete cosine transform
  • DST discrete sine transform
  • the transform processing unit 206 may be configured to apply integer approximations of DCT/DST, such as the transforms specified for H.265/HEVC. Compared to an orthogonal DCT transform, such integer approximations are typically scaled by a certain factor. In order to preserve the norm of the residual block which is processed by forward and inverse transforms, additional scaling factors are applied as part of the transform process.
  • the scaling factors are typically chosen based on certain constraints like scaling factors being a power of two for shift operations, bit depth of the transform coefficients, tradeoff between accuracy and implementation costs, etc. Specific scaling factors are, for example, specified for the inverse transform, e.g. by inverse transform processing unit 212 (and the
  • corresponding inverse transform e.g. by inverse transform processing unit 312 at video decoder 30
  • corresponding scaling factors for the forward transform e.g. by transform processing unit 206, at an encoder 20 may be specified accordingly.
  • Embodiments of the video encoder 20 may be configured to output transform parameters, e.g. a type of transform or transforms, e.g.
  • the video decoder 30 may receive and use the transform parameters for decoding.
  • the quantization unit 208 may be configured to quantize the transform coefficients 207 to obtain quantized coefficients 209, e.g. by applying scalar quantization or vector quantization.
  • the quantized coefficients 209 may also be referred to as quantized transform coefficients 209 or quantized residual coefficients 209.
  • the quantization process may reduce the bit depth associated with some or all of the transform coefficients 207. For example, an n-bit transform coefficient may be rounded down to an m-bit Transform coefficient during quantization, where n is greater than m.
  • the degree of quantization may be modified by adjusting a quantization parameter (QP). For example for scalar quantization, different scaling may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, whereas larger quantization step sizes correspond to coarser quantization.
  • the applicable quantization step size may be indicated by a quantization parameter (QP).
  • the quantization parameter may for example be an index to a predefined set of applicable quantization step sizes. For example, small quantization parameters may correspond to fine quantization (small quantization step sizes) and large quantization parameters may correspond to coarse quantization (large
  • the quantization may include division by a
  • quantization step size and a corresponding and/or the inverse dequantization may include multiplication by the quantization step size.
  • Embodiments according to some standards may be configured to use a quantization parameter to determine the quantization step size.
  • the quantization step size may be calculated based on a quantization parameter using a fixed point approximation of an equation including division. Additional scaling factors may be introduced for quantization and dequantization to restore the norm of the residual block, which might get modified because of the scaling used in the fixed point approximation of the equation for quantization step size and quantization parameter.
  • the scaling of the inverse transform and dequantization might be combined.
  • customized quantization tables may be used and signaled from an encoder to a decoder, e.g. in a bitstream.
  • the quantization is a lossy operation, wherein the loss increases with increasing quantization step sizes.
  • the inverse quantization unit 210 is configured to apply the inverse quantization of the quantization unit 208 on the quantized coefficients to obtain dequantized coefficients 211 , e.g. by applying the inverse of the quantization scheme applied by the quantization unit 208 based on or using the same quantization step size as the quantization unit 208.
  • the dequantized coefficients 21 1 may also be referred to as dequantized residual coefficients 211 and correspond - although typically not identical to the transform coefficients due to the loss by quantization - to the transform coefficients 207.
  • the inverse transform processing unit 212 is configured to apply the inverse transform of the transform applied by the transform processing unit 206, e.g. an inverse discrete cosine transform (DCT) or inverse discrete sine transform (DST) or other inverse transforms, to obtain a reconstructed residual block 213 (or corresponding dequantized coefficients 213) in the sample domain.
  • the reconstructed residual block 213 may also be referred to as transform block 213.
  • the reconstruction unit 214 (e.g. adder or summer 214) is configured to add the transform block 213 (i.e. reconstructed residual block 213) to the prediction block 265 to obtain a reconstructed block 215 in the sample domain, e.g. by adding - sample by sample - the sample values of the reconstructed residual block 213 and the sample values of the prediction block 265.
  • the loop filter unit 220 (or short“loop filter” 220), is configured to filter the reconstructed block 215 to obtain a filtered block 221 , or in general, to filter reconstructed samples to obtain filtered samples.
  • the loop filter unit is, e.g., configured to smooth pixel transitions, or otherwise improve the video quality.
  • the loop filter unit 220 may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof.
  • the loop filter unit 220 is shown in FIG. 2 as being an in loop filter, in other configurations, the loop filter unit 220 may be implemented as a post loop filter.
  • the filtered block 221 may also be referred to as filtered reconstructed block 221.
  • Embodiments of the video encoder 20 may be configured to output loop filter parameters (such as sample adaptive offset information), e.g. directly or encoded via the entropy encoding unit 270, so that, e.g., a decoder 30 may receive and apply the same loop filter parameters or respective loop filters for decoding.
  • loop filter parameters such as sample adaptive offset information
  • the decoded picture buffer (DPB) 230 may be a memory that stores reference pictures, or in general reference picture data, for encoding video data by video encoder 20.
  • the DPB 230 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
  • the decoded picture buffer (DPB) 230 may be configured to store one or more filtered blocks 221.
  • the decoded picture buffer 230 may be further configured to store other previously filtered blocks, e.g. previously reconstructed and filtered blocks 221 , of the same current picture or of different pictures, e.g.
  • the decoded picture buffer (DPB) 230 may be also configured to store one or more unfiltered reconstructed blocks 215, or in general unfiltered reconstructed samples, e.g. if the reconstructed block 215 is not filtered by loop filter unit 220, or any other further processed version of the reconstructed blocks or samples.
  • the mode selection unit 260 comprises partitioning unit 262, inter-prediction unit 244 and intra-prediction unit 254, and is configured to receive or obtain original picture data, e.g. an original block 203 (current block 203 of the current picture 17), and reconstructed picture data, e.g. filtered and/or unfiltered reconstructed samples or blocks of the same (current) picture and/or from one or a plurality of previously decoded pictures, e.g. from decoded picture buffer 230 or other buffers (e.g. line buffer, not shown).
  • the reconstructed picture data is used as reference picture data for prediction, e.g. inter-prediction or intra-prediction, to obtain a prediction block 265 or predictor 265.
  • Mode selection unit 260 may be configured to determine or select a partitioning for a current block prediction mode (including no partitioning) and a prediction mode (e.g. an intra or inter prediction mode) and generate a corresponding prediction block 265, which is used for the calculation of the residual block 205 and for the reconstruction of the reconstructed block 215.
  • a prediction mode e.g. an intra or inter prediction mode
  • Embodiments of the mode selection unit 260 may be configured to select the partitioning and the prediction mode (e.g. from those supported by or available for mode selection unit 260), which provide the best match or in other words the minimum residual (minimum residual means better compression for transmission or storage), or a minimum signaling overhead (minimum signaling overhead means better compression for transmission or storage), or which considers or balances both.
  • the mode selection unit 260 may be configured to determine the partitioning and prediction mode based on rate distortion optimization (RDO), i.e. select the prediction mode which provides a minimum rate distortion.
  • RDO rate distortion optimization
  • Terms like“best”, “minimum”,“optimum” etc. in this context do not necessarily refer to an overall“best”, “minimum”,“optimum”, etc. but may also refer to the fulfillment of a termination or selection criterion like a value exceeding or falling below a threshold or other constraints leading potentially to a“sub-optimum selection” but reducing complexity and processing time.
  • the partitioning unit 262 may be configured to partition the block 203 into smaller block partitions or sub-blocks (which form again blocks), e.g. iteratively using quad- tree-partitioning (QT), binary partitioning (BT) or triple-tree-partitioning (TT) or any combination thereof, and to perform, e.g., the prediction for each of the block partitions or sub-blocks, wherein the mode selection comprises the selection of the tree-structure of the partitioned block 203 and the prediction modes are applied to each of the block partitions or sub-blocks.
  • QT quad- tree-partitioning
  • BT binary partitioning
  • TT triple-tree-partitioning
  • partitioning e.g. by partitioning unit 260
  • prediction processing by inter-prediction unit 244 and intra-prediction unit 254
  • the partitioning unit 262 may partition (or split) a current block 203 into smaller partitions, e.g. smaller blocks of square or rectangular size. These smaller blocks (which may also be referred to as sub-blocks) may be further partitioned into even smaller partitions.
  • This is also referred to tree-partitioning or hierarchical tree-partitioning, wherein a root block, e.g. at root tree-level 0 (hierarchy-level 0, depth 0), may be recursively partitioned, e.g. partitioned into two or more blocks of a next lower tree-level, e.g.
  • nodes at tree-level 1 (hierarchy-level 1 , depth 1 ), wherein these blocks may be again partitioned into two or more blocks of a next lower level, e.g. tree-level 2 (hierarchy-level 2, depth 2), etc. until the partitioning is terminated, e.g. because a termination criterion is fulfilled, e.g. a maximum tree depth or minimum block size is reached.
  • Blocks which are not further partitioned are also referred to as leaf-blocks or leaf nodes of the tree.
  • a tree using partitioning into two partitions is referred to as binary-tree (BT)
  • BT binary-tree
  • TT ternary- tree
  • QT quad-tree
  • the term“block” as used herein may be a portion, in particular a square or rectangular portion, of a picture.
  • the block may be or correspond to a coding tree unit (CTU), a coding unit (CU), prediction unit (PU), and transform unit (TU) and/or to the corresponding blocks, e.g. a coding tree block (CTB), a coding block (CB), a transform block (TB) or prediction block (PB).
  • CTU coding tree unit
  • CU coding unit
  • PU prediction unit
  • TU transform unit
  • a coding tree block CB
  • CB coding block
  • TB transform block
  • PB prediction block
  • a coding tree unit may be or comprise a 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 colour planes and syntax structures used to code the samples.
  • a coding tree block may be an NxN block of samples for some value of N such that the division of a component into CTBs is a partitioning.
  • a coding unit may be or comprise a coding block of luma samples, two corresponding coding blocks of chroma samples of a picture that has three sample arrays, or a coding block of samples of a monochrome picture or a picture that is coded using three separate colour planes and syntax structures used to code the samples.
  • a coding block may be an MxN block of samples for some values of M and N such that the division of a CTB into coding blocks is a partitioning.
  • a coding tree unit may be split into CUs by using a quad-tree structure denoted as coding tree.
  • the decision whether to code a picture area using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level.
  • Each CU can be further split into one, two or four PUs according to the PU splitting type. Inside one PU, the same prediction process is applied and the relevant information is transmitted to the decoder on a PU basis.
  • a CU can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for the CU.
  • a combined Quad-tree and binary tree (QTBT) partitioning is for example used to partition a coding block.
  • a CU can have either a square or rectangular shape.
  • a coding tree unit (CTU) is first partitioned by a quadtree structure.
  • the quadtree leaf nodes are further partitioned by a binary tree or ternary (or triple) tree structure.
  • the partitioning tree leaf nodes are called coding units (CUs), and that segmentation is used for prediction and transform processing without any further partitioning.
  • CUs coding units
  • multiple partition for example, triple tree partition may be used together with the QTBT block structure.
  • the mode selection unit 260 of video encoder 20 may be configured to perform any combination of the partitioning techniques described herein.
  • the video encoder 20 is configured to determine or select the best or an optimum prediction mode from a set of (e.g. pre-determined) prediction modes.
  • the set of prediction modes may comprise, e.g., intra-prediction modes and/or inter-prediction modes.
  • the set of intra-prediction modes may comprise 35 different intra-prediction modes, e.g. non-directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined in HEVC, or may comprise 67 different intra-prediction modes, e.g. non- directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined for WC.
  • the intra-prediction unit 254 is configured to use reconstructed samples of neighboring blocks of the same current picture to generate an intra-prediction block 265 according to an intra-prediction mode of the set of intra-prediction modes.
  • the intra prediction unit 254 (or in general the mode selection unit 260) is further configured to output intra-prediction parameters (or in general information indicative of the selected intra prediction mode for the block) to the entropy encoding unit 270 in form of syntax
  • the video decoder 30 may receive and use the prediction parameters for decoding.
  • the set of (or possible) inter-prediction modes depends on the available reference pictures (i.e. previous at least partially decoded pictures, e.g. stored in DBP 230) and other interprediction parameters, e.g. whether the whole reference picture or only a part, e.g. a search window area around the area of the current block, of the reference picture is used for searching for a best matching reference block, and/or e.g. whether pixel interpolation is applied, e.g. half/semi-pel and/or quarter-pel interpolation, or not.
  • other interprediction parameters e.g. whether the whole reference picture or only a part, e.g. a search window area around the area of the current block, of the reference picture is used for searching for a best matching reference block, and/or e.g. whether pixel interpolation is applied, e.g. half/semi-pel and/or quarter-pel interpolation, or not.
  • skip mode and/or direct mode may be applied.
  • the inter prediction unit 244 may include a motion estimation (ME) unit and a motion compensation (MC) unit (both not shown in Fig.2).
  • the motion estimation unit may be configured to receive or obtain the picture block 203 (current picture block 203 of the current picture 17) and a decoded picture 231 , or at least one or a plurality of previously
  • reconstructed blocks e.g. reconstructed blocks of one or a plurality of other/different previously decoded pictures 231 , for motion estimation.
  • a video sequence may comprise the current picture and the previously decoded pictures 231 , or in other words, the current picture and the previously decoded pictures 231 may be part of or form a sequence of pictures forming a video sequence.
  • the encoder 20 may, e.g., be configured to select a reference block from a plurality of reference blocks of the same or different pictures of the plurality of other pictures and provide a reference picture (or reference picture index) and/or an offset (spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block as inter prediction parameters to the motion estimation unit.
  • This offset is also called motion vector (MV).
  • the motion compensation unit is configured to obtain, e.g. receive, an inter prediction parameter and to perform inter prediction based on or using the inter prediction parameter to obtain an inter prediction block 265.
  • Motion compensation, performed by the motion compensation unit may involve fetching or generating the prediction block based on the motion/block vector determined by motion estimation, possibly performing interpolations to sub-pixel precision.
  • Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that may be used to code a picture block.
  • the motion compensation unit may locate the prediction block to which the motion vector points in one of the reference picture lists.
  • the motion compensation unit may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding the picture blocks of the video slice.
  • syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding the picture blocks of the video slice.
  • tile groups and/or tiles and respective syntax elements may be generated or used.
  • the entropy encoding unit 270 is configured to apply, for example, an entropy encoding algorithm or scheme (e.g. a variable length coding (VLC) scheme, an context adaptive VLC scheme (CAVLC), an arithmetic coding scheme, a binarization, a context adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding or another entropy encoding methodology or technique) or bypass (no compression) on the quantized coefficients 209, inter prediction parameters, intra prediction parameters, loop filter parameters and/or other syntax elements to obtain encoded picture data 21 which can be output via the output 272, e.g.
  • an entropy encoding algorithm or scheme e.g. a variable length coding (VLC) scheme, an context adaptive VLC scheme (CAVLC), an arithmetic coding scheme, a binarization, a context adaptive binary a
  • an encoded bitstream 21 in the form of an encoded bitstream 21 , so that, e.g., the video decoder 30 may receive and use the parameters for decoding, .
  • the encoded bitstream 21 may be transmitted to video decoder 30, or stored in a memory for later transmission or retrieval by video decoder 30.
  • a non-transform based encoder 20 can quantize the residual signal directly without the transform processing unit 206 for certain blocks or frames.
  • a non-transform based encoder 20 can quantize the residual signal directly without the transform processing unit 206 for certain blocks or frames.
  • an encoder 20 can have the quantization unit 208 and the inverse quantization unit 210 combined into a single unit. Decoder and Decoding Method
  • Fig. 3 shows an example of a video decoder 30 that is configured to implement the techniques of this present application.
  • the video decoder 30 is configured to receive encoded picture data 21 (e.g. encoded bitstream 21 ), e.g. encoded by encoder 20, to obtain a decoded picture 331.
  • the encoded picture data or bitstream comprises information for decoding the encoded picture data, e.g. data that represents picture blocks of an encoded video slice (and/or tile groups or tiles) and associated syntax elements.
  • the decoder 30 comprises an entropy decoding unit 304, an inverse quantization unit 310, an inverse transform processing unit 312, a reconstruction unit 314 (e.g. a summer 314), a loop filter 320, a decoded picture buffer (DBP) 330, a mode application unit 360, an inter prediction unit 344 and an intra prediction unit 354.
  • Inter prediction unit 344 may be or include a motion compensation unit.
  • Video decoder 30 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 100 from FIG. 2.
  • the inverse quantization unit 310 may be identical in function to the inverse quantization unit 1 10
  • the inverse transform processing unit 312 may be identical in function to the inverse transform processing unit 212
  • the reconstruction unit 314 may be identical in function to reconstruction unit 214
  • the loop filter 320 may be identical in function to the loop filter 220
  • the decoded picture buffer 330 may be identical in function to the decoded picture buffer 230. Therefore, the explanations provided for the respective units and functions of the video 20 encoder apply correspondingly to the respective units and functions of the video decoder 30.
  • the entropy decoding unit 304 is configured to parse the bitstream 21 (or in general encoded picture data 21 ) and perform, for example, entropy decoding to the encoded picture data 21 to obtain, e.g., quantized coefficients 309 and/or decoded coding parameters (not shown in Fig. 3), e.g. any or all of inter prediction parameters (e.g. reference picture index and motion vector), intra prediction parameter (e.g. intra prediction mode or index), transform parameters, quantization parameters, loop filter parameters, and/or other syntax elements.
  • Entropy decoding unit 304 maybe configured to apply the decoding algorithms or schemes corresponding to the encoding schemes as described with regard to the entropy encoding unit 270 of the encoder 20.
  • Entropy decoding unit 304 may be further configured to provide inter prediction parameters, intra prediction parameter and/or other syntax elements to the mode application unit 360 and other parameters to other units of the decoder 30.
  • Video decoder 30 may receive the syntax elements at the video slice level and/or the video block level.
  • tile groups and/or tiles and respective syntax elements may be received and/or used.
  • the inverse quantization unit 310 may be configured to receive quantization parameters (QP) (or in general information related to the inverse quantization) and quantized coefficients from the encoded picture data 21 (e.g. by parsing and/or decoding, e.g. by entropy decoding unit 304) and to apply based on the quantization parameters an inverse quantization on the decoded quantized coefficients 309 to obtain dequantized coefficients 311 , which may also be referred to as transform coefficients 31 1.
  • the inverse quantization process may include use of a quantization parameter determined by video encoder 20 for each video block in the video slice (or tile or tile group) to determine a degree of quantization and, likewise, a degree of inverse quantization that should be applied.
  • Inverse transform processing unit 312 may be configured to receive dequantized coefficients 311 , also referred to as transform coefficients 31 1 , and to apply a transform to the dequantized coefficients 311 in order to obtain reconstructed residual blocks 213 in the sample domain.
  • the reconstructed residual blocks 213 may also be referred to as transform blocks 313.
  • the transform may be an inverse transform, e.g., an inverse DCT, an inverse DST, an inverse integer transform, or a conceptually similar inverse transform process.
  • the inverse transform processing unit 312 may be further configured to receive transform parameters or corresponding information from the encoded picture data 21 (e.g. by parsing and/or decoding, e.g. by entropy decoding unit 304) to determine the transform to be applied to the dequantized coefficients 311.
  • the reconstruction unit 314 (e.g. adder or summer 314) may be configured to add the reconstructed residual block 313, to the prediction block 365 to obtain a reconstructed block 315 in the sample domain, e.g. by adding the sample values of the reconstructed residual block 313 and the sample values of the prediction block 365.
  • the loop filter unit 320 (either in the coding loop or after the coding loop) is configured to filter the reconstructed block 315 to obtain a filtered block 321 , e.g. to smooth pixel transitions, or otherwise improve the video quality.
  • the loop filter unit 320 may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof.
  • the loop filter unit 320 is shown in FIG. 3 as being an in loop filter, in other configurations, the loop filter unit 320 may be implemented as a post loop filter.
  • decoded video blocks 321 of a picture are then stored in decoded picture buffer 330, which stores the decoded pictures 331 as reference pictures for subsequent motion compensation for other pictures and/or for output respectively display.
  • the decoder 30 is configured to output the decoded picture 31 1 , e.g. via output 312, for presentation or viewing to a user.
  • the inter prediction unit 344 may be identical to the inter prediction unit 244 (in particular to the motion compensation unit) and the intra prediction unit 354 may be identical to the inter prediction unit 254 in function, and performs split or partitioning decisions and prediction based on the partitioning and/or prediction parameters or respective information received from the encoded picture data 21 (e.g. by parsing and/or decoding, e.g. by entropy decoding unit 304).
  • Mode application unit 360 may be configured to perform the prediction (intra or inter prediction) per block based on reconstructed pictures, blocks or respective samples (filtered or unfiltered) to obtain the prediction block 365.
  • intra prediction unit 354 of mode application unit 360 is configured to generate prediction block 365 for a picture block of the current video slice based on a signaled intra prediction mode and data from previously decoded blocks of the current picture.
  • inter prediction unit 344 e.g. motion compensation unit
  • the prediction blocks may be produced from one of the reference pictures within one of the reference picture lists.
  • Video decoder 30 may construct the reference frame lists, List 0 and List 1 , using default construction techniques based on reference pictures stored in DPB 330. The same or similar may be applied for or by embodiments using tile groups (e.g. video tile groups) and/or tiles (e.g. video tiles) in addition or alternatively to slices (e.g. video slices), e.g. a video may be coded using I, P or B tile groups and /or tiles.
  • tile groups e.g. video tile groups
  • tiles e.g. video tiles
  • slices e.g. video slices
  • Mode application unit 360 is configured to determine the prediction information for a video block of the current video slice by parsing the motion vectors or related information and other syntax elements, and uses the prediction information to produce the prediction blocks for the current video block being decoded. For example, the mode application unit 360 uses some of the received syntax elements to determine a prediction mode (e.g., intra or inter prediction) used to code the video blocks of the video slice, an inter prediction slice type (e.g., B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists for the slice, motion vectors for each inter encoded video block of the slice, inter prediction status for each inter coded video block of the slice, and other information to decode the video blocks in the current video slice.
  • a prediction mode e.g., intra or inter prediction
  • an inter prediction slice type e.g., B slice, P slice, or GPB slice
  • construction information for one or more of the reference picture lists for the slice motion vectors for each inter encoded video block of the slice, inter prediction status for each
  • tile groups e.g. video tile groups
  • tiles e.g. video tiles
  • slices e.g. video slices
  • Embodiments of the video decoder 30 as shown in Fig. 3 may be configured to partition and/or decode the picture by using slices (also referred to as video slices), wherein a picture may be partitioned into or decoded using one or more slices (typically non-overlapping), and each slice may comprise one or more blocks (e.g. CTUs).
  • slices also referred to as video slices
  • each slice may comprise one or more blocks (e.g. CTUs).
  • Embodiments of the video decoder 30 as shown in Fig. 3 may be configured to partition and/or decode the picture by using tile groups (also referred to as video tile groups) and/or tiles (also referred to as video tiles), wherein a picture may be partitioned into or decoded using one or more tile groups (typically non-overlapping), and each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g. complete or fractional blocks.
  • tile groups also referred to as video tile groups
  • tiles also referred to as video tiles
  • each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g. complete or fractional blocks.
  • the video decoder 30 can be used to decode the encoded picture data 21.
  • the decoder 30 can produce the output video stream without the loop filtering unit 320.
  • a non-transform based decoder 30 can inverse-quantize the residual signal directly without the inverse-transform processing unit 312 for certain blocks or frames.
  • the video decoder 30 can have the inverse-quantization unit 310 and the inverse-transform processing unit 312 combined into a single unit.
  • a processing result of a current step may be further processed and then output to the next step.
  • a further operation such as Clip or shift, may be performed on the processing result of the interpolation filtering, motion vector derivation or loop filtering.
  • the value of motion vector is constrained to a predefined range according to its representing bit. If the representing bit of motion vector is bitDepth, then the range is - 2 A (bitDepth-1) ⁇ 2 A (bitDepth-1 )-1 , where“ A " means exponentiation. For example, if bitDepth is set equal to 16, the range is -32768 ⁇ 32767; if bitDepth is set equal to 18, the range is - 131072 ⁇ 131071.
  • the value of the derived motion vector (e.g. the MVs of four 4x4 sub-blocks within one 8x8 block) is constrained such that the max difference between integer parts of the four 4x4 sub-block MVs is no more than N pixels, such as no more than 1 pixel.
  • N pixels such as no more than 1 pixel.
  • mvx is a horizontal component of a motion vector of an image block or a sub-block
  • mvy is a vertical component of a motion vector of an image block or a sub-block
  • ux and uy indicates an intermediate value
  • FIG.4 is a schematic diagram of a video coding device 400 according to an embodiment of the disclosure.
  • the video coding device 400 is suitable for implementing the disclosed embodiments as described herein.
  • the video coding device 400 may be a decoder such as video decoder 30 of FIG. 1A or an encoder such as video encoder 20 of FIG. 1A.
  • the video coding device 400 comprises ingress ports 410 (or input ports 410) and receiver units (Rx) 420 for receiving data; a processor, logic unit, or central processing unit (CPU) 430 to process the data; transmitter units (Tx) 440 and egress ports 450 (or output ports 450) for transmitting the data; and a memory 460 for storing the data.
  • the video coding device 400 may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components coupled to the ingress ports 410, the receiver units 420, the transmitter units 440, and the egress ports 450 for egress or ingress of optical or electrical signals.
  • OE optical-to-electrical
  • EO electrical-to-optical
  • the processor 430 is implemented by hardware and software.
  • the processor 430 may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), FPGAs, ASICs, and DSPs.
  • the processor 430 is in communication with the ingress ports 410, receiver units 420, transmitter units 440, egress ports 450, and memory 460.
  • the processor 430 comprises a coding module 470.
  • the coding module 470 implements the disclosed embodiments described above. For instance, the coding module 470
  • the coding module 470 implements, processes, prepares, or provides the various coding operations.
  • the inclusion of the coding module 470 therefore provides a substantial improvement to the functionality of the video coding device 400 and effects a transformation of the video coding device 400 to a different state.
  • the coding module 470 is implemented as instructions stored in the memory 460 and executed by the processor 430.
  • the memory 460 may comprise one or more disks, tape drives, and solid-state drives and may be used as an over-flow data storage device, to store programs when such programs are selected for execution, and to store instructions and data that are read during program execution.
  • the memory 460 may be, for example, volatile and/or non-volatile and may be a read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and/or static random-access memory (SRAM).
  • Fig. 5 is a simplified block diagram of an apparatus 500 that may be used as either or both of the source device 12 and the destination device 14 from Fig. 1 according to an exemplary embodiment.
  • a processor 502 in the apparatus 500 can be a central processing unit.
  • the processor 502 can be any other type of device, or multiple devices, capable of manipulating or processing information now-existing or hereafter developed.
  • the disclosed implementations can be practiced with a single processor as shown, e.g., the processor 502, advantages in speed and efficiency can be achieved using more than one processor.
  • a memory 504 in the apparatus 500 can be a read only memory (ROM) device or a random access memory (RAM) device in an implementation. Any other suitable type of storage device can be used as the memory 504.
  • the memory 504 can include code and data 506 that is accessed by the processor 502 using a bus 512.
  • the memory 504 can further include an operating system 508 and application programs 510, the application programs 510 including at least one program that permits the processor 502 to perform the methods described here.
  • the application programs 510 can include applications 1 through N, which further include a video coding application that performs the methods described here.
  • the apparatus 500 can also include one or more output devices, such as a display 518.
  • the display 518 may be, in one example, a touch sensitive display that combines a display with a touch sensitive element that is operable to sense touch inputs.
  • the display 518 can be coupled to the processor 502 via the bus 512.
  • the bus 512 of the apparatus 500 can be composed of multiple buses.
  • the secondary storage 514 can be directly coupled to the other components of the apparatus 500 or can be accessed via a network and can comprise a single integrated unit such as a memory card or multiple units such as multiple memory cards.
  • the apparatus 500 can thus be implemented in a wide variety of configurations.
  • Triangular partitioning mode TPM
  • geometric motion partitioning GMP
  • TMP Triangular partitioning mode
  • GMP geometric motion partitioning
  • Weights applied to chroma components of corresponding prediction units may differ from weights applied to luma components of corresponding prediction units.
  • MergeTriangleFlag is a flag that identifies whether TPM is selected or not (“0” means that TPM is not selected; otherwise, TPM is chosen); merge_triangle_split_dir is a split direction flag for TPM (“0” means the split direction from top-left corner to the below-right corner; otherwise, the split direction is from top-right corner to the below-left corner); merge_triangle_idxO and merge_triangle_idx1 are indices of merge candidates 0 and 1 used for TPM.
  • TPM is described in the following proposal: R-L. Liao and C.S. Lim
  • Prediction errors are localized only in near-boundary region that covers the boundary between partitions that use a more compact representation. Transform and quantization are performed only for this near-boundary region.
  • a near-boundary region is defined by start and end side positions, wherein the first of the side positions is located on first side of the block, a side of the block is top, left, right or bottom; and the second side position is located on the second side of the block, and wherein the first side of the block is not the same as the second side of a block.
  • the near-boundary region could be defined by a curve that connects the first and the second positions and includes the near-boundary region of the samples with the distance to the curve not exceeding a distance threshold. This threshold is set to 2.
  • rows of a subsampled block are obtained by selecting a set of samples from a range of rows of a block of residual signal, wherein the start position for the first row of the range is specified as the first side position and the end position is specified for the last row of the range as the end position, and wherein a sampling position is specified for each of the rows between the first row and the last row of the range so that the sampling position is a monotonic function of the row position within a block, and wherein the set of samples comprises the samples for which the distance to the sampling position of the row is not greater than the distance threshold.
  • columns of a subsampled block are obtained by selecting a set of samples from a range of columns of a block of a residual signal, wherein the start position for the first column of the range is specified as the first side position and the end position is specified for the last column of the range as the end position, and wherein a sampling position is specified for each of the columns between the first column and the last column of the range so that the sampling position is a monotonic function of the column position within a block, and wherein the set of samples comprises the samples for which the distance to the sampling position of the column is not greater than the distance threshold.
  • the distance threshold is smaller than corresponding block side length, i.e. it could be set to half of the height or half of the width of the block.
  • Embodiments described herein disclose a mechanism of resampling a block to obtain this near-boundary region that is processed as a transform block / transform unit.
  • Prediction unit PU1 601 and prediction unit PU2 602 are combined using TPM technique to get a predictor, wherein a prediction error is calculated for these units.
  • a residue block contains 2 zero-residue regions 611 and 612, and region 613 is resampled into a transform block (TB) 623, that the TB623 represents residues for a color component of a transform unit (TU).
  • regions 61 1 and 612 residues are assumed to be zero, whereas residual should be non zero in region 613.
  • region 613 covers the area where weights at least for one prediction unit PU1 or PU2 are non-zero.
  • residue signal from region 613 can be resampled into transform block 623 by reading samples from memory row-wise or column-wise.
  • non-zero residuals showed in region 701 covers a part of the area where weights at least for one prediction unit PU1 or PU2 are non-zero.
  • regions 702 and 703 residues are assumed to be quantized out to zero. So, transform block 704 that represents residues for a color component of a transform unit (TU) is the result of resampling region 701.
  • processing steps for the TPM case are presented as 2 flow-charts for decoder and encoder, respectively.
  • step 801 residual data are decoded, inverse quantization and inverse transform (if any) are performed to obtain transform blocks (TBs) of a TU.
  • inverse resampling 802 restores residues within each transform block (TB) of a TU placing samples of a transform blocks at corresponding positions within a residue block.
  • Fig. 6 The correspondence between sample positions in region 613 and sample positions in transform block 623 of a TU is demonstrated in Fig. 6. Similarly, this
  • Step 803 corresponds to PU reconstruction using the restored residues and TPM predictor.
  • the order of actions shown in Fig. 8 for TPM is as follows.
  • step 811 prediction process is fulfilled to get a predictor for a unit, residues are obtained according to the predictor.
  • samples corresponds to region 613 in Fig. 6 or region 701 in Fig. 7 are fetched from memory either row-wise or column-wise to get transform blocks of a TU. Forward transform, quantization and residual coding are performed as in step 813.
  • regions 902, 904, 912 and 914 residues are assumed to be zero.
  • the boundary between regions 902 and 904 is shown by line 903, whereas the boundary between regions 912 and 914 is shown by line 913.
  • the near-boundary regions 901 or 91 1 cover the area between regions 902 and 904 as well as 912 and 914 in different ways as Fig. 9 illustrates, respectively.
  • regions 901 or 91 1 are resampled into transform blocks of different shapes 905 and 915, respectively.
  • step 1001 residual are decoded, inverse quantization and inverse transform (if any) are performed to obtain transform blocks of a TU. Then, inverse resampling 1002 should restore residues within each transform block of a TU, placing samples of a transform blocks at corresponding positions within a residue blocks.
  • Fig. 9 Regions 902, 904, 912 and 914 in Fig. 9 are filled in by zero.
  • Final step 1003 corresponds to PU reconstruction using the restored residues and GMP predictor.
  • step 101 1 prediction process is fulfilled to get a predictor for a unit and then residues are obtained.
  • step 1012 samples corresponds to regions 901 and 911 in Fig. 9 are fetched from memory either row-wise or column-wise to get transform blocks of a TU.
  • step 1013 forward transform, quantization and residual coding are performed as in step 1013.
  • the proposed mechanism adds one more state that should be signal.
  • Fig. 11 we disclose a signaling mechanism for the proposed method exemplarily applied to TPM.
  • steps 1 101 and 1102 the value of the flags MergeTriagleFlag and cbf are checked. If the values of both MergeTriagleFlag and cbf flags is set to 1 , then the flag ShapeAdaptiveResamplingFlag should be checked. At the encoder side, its value can be iterated in Rate-Distortion
  • ShapeAdaptiveResamplingFlag 1 , resampling for transform blocks.
  • cbf Coded Block Flag
  • cu_cbf for an entire coding unit (CU)
  • tu_cbf_luma tu_cbf_cb
  • tu_cbf_cr tu_cbf_cr
  • cbf in step 1102 may denote any of this flag.
  • the meaning of this flag is different in each case. If cu_cbf is checked, then the proposed resampling is applied to each color component. Otherwise, it is used only for a concrete color component (luma, Cb, or Cr).
  • the height of a region to be resampled and, therefore, the height of a TB can be different.
  • the height of region 613 in Fig. 6 differs the height of region 701 in Fig. 7.
  • the height of a region to be resampled and, therefore, the height of a TB should be adjustable.
  • the 1 st mechanism to adjust the height of a region to be resampled and, therefore, the height of a TB is to derive it using an entire block shape and size.
  • the 2 nd mechanism to adjust the height of a region to be resampled and, therefore, the height of a TB is to signal it in a bit-stream as shown in Fig. 12.
  • Steps 1201-1203 are same as steps 1101-1103 in Fig. 11.
  • the value of ShapeAdaptiveResamplingFlag is checked whether it equals 1 or not.
  • ShapeAdaptiveResamplingFlag 1
  • the syntax element ShapeAdaptiveResampling should be read from memory (at the encoder side) or parsed from a bit-stream (at the decoder side) at step 1205.
  • Different codes can be used to encode or decode the syntax element ShapeAdaptiveResampling. For example, if it is necessary to choose only between 2 values of the heights of a region to be resampled and, therefore, the height of a TB, 1 bin flag can be used. If more options (3 or more variants of the height) are available, unary truncated code, fixed-length code, exponential Golomb-Rice code, etc. might be used as codes.
  • Fetch sample p[x][y] locates within region 1301 immediately on block boundaries and marked by white circles in Fig. 13;
  • the proposed deblocking filter is directional.
  • the propagation directions are marked by arrows 1304 and 1305 in Fig. 13.
  • Fig. 14 Another mechanism to deblock boundaries between regions 1401 and 1402 as well as 1401 and 1403 is presented in Fig. 14.
  • Spatial filter of (2 w +1)x(2 M +1) size (where N and M are non-zero integer values which can, but are not necessarily equal and can thus also be different from each other) are applied on the boundaries between regions 1401 and 1402 as well as 1401 and 1403 so that the spatial filter is fed by a group of samples that contains at least one sample belonging to region 1401 and at least one sample belonging to region 1402 or 1403.
  • regions where spatial filter is applied have sizes of of 3x3 and are denoted by 1404 and 1405 have size.
  • This spatial filter should relate to the type of low-pass smoothing filters. If a 3x3 Gaussian filter is used, its coefficients can be as follows:
  • a near boundary region is defined by the partitioning process of GMP that subdivides a PU onto two regions using a straight line. This line has an intersection with the PU boundary in two points corresponding to two integer positions. There are 6 cases of partitioning, four of these cases split PU into one triangle and 1 pentagon area, and the rest two cases split PU into two trapeze areas.
  • these two positions are located on top and bottom side, or on the left and right sides of the PU.
  • ⁇ x E ,y E ⁇ denote start and end positions, shown in Fig 15 and Fig 16 respectively, for a colomn-wise and a row-wise scans.
  • STB denotes heightrB (Fig 15) or widttiTB (Fig 16) of the subsampled block and is further referred to as a subsampling width Sw.
  • samples of the subsampled block B(x,y) are obtained from PU samples p(x,y) as follows:
  • samples of the subsampled block B(x,y ) are obtained from PU samples p(x,y) as follows:
  • selection of the scan depends on whether a horizontal or vertical component of the start and end positions are closer to the corner that is aligned with the resulting triangle.
  • x s - x E is quantized to the closest power-of-two value and a column-wise scan is applied.
  • S w is selected in such a way that the resulting near-boundary region is inside the PU.
  • Geometrical partitioning Another mechanism of non-rectangular partitioning known as Geometrical partitioning (GEO) was disclosed in contribution JVET-O0489“Non-CE4: Geometrical partitioning for inter blocks” by S. Esenlik, H. Gao, A. Filippov, V. Rufitskiy, A.M. Kotra, B. Wang, Z. Zhao, E. Alshina, M. Blaser, J. Sauer) to the 16 th JVET meeting, Gothenburg, Sweden, July 2019.
  • GEO is very similar to GMP using a subset of GMP’s features and capabilities.
  • Fig. 17 illustrates how shape-adaptive resampling can be applied to a block where GEO is used.
  • Fig. 17 illustrates how shape-adaptive resampling can be applied to a block where GEO is used.
  • modes 1810 and 1820 correspond to TPM with different values of a split flag.
  • Subblocks 181 1 and 1812 as well as subblocks 1821 and 1822 denote both prediction blocks for triangular partitioning modes 1810 and 1820, respectively.
  • Partitioning modes 1830, 1840, 1850, 1860, 1870, 1880, and 1890 are beyond the capabilities of the VTM-6.0 software and WC specification draft version 6. These modes are generated by GEO. Each of them requires two prediction blocks such as 1831 and 1832 for partitioning mode 1830.
  • a prediction block defines an inter-predictor that can be taken only out of a set of merge candidates also known as merge candidate list. In fact, mechanisms of constructing the merge candidate list are shared by (i.e. is the same for) both TPM and GEO.
  • MaxNumTriangleMergeCand may be derived as follows:
  • MaxNumTriangleMergeCand MaxNumMergeCand - max_num_merge_cand_minus_max_num_triangle_cand.
  • MaxNumTriangleMergeCand When max_num_merge_cand_minus_max_num_triangle_cand is present in a slice header, the value of MaxNumTriangleMergeCand shall be in the range of 2 to
  • MaxNumTriangleMergeCand is set equal to 0. When MaxNumTriangleMergeCand is equal to 0, triangle merge mode is not allowed for the current slice.
  • sps_triangle_enabled_flag specifies whether triangular shape based motion compensation (also known as TPM or triangular prediction mode) can be used for inter prediction.
  • sps_triangle_enabled_flag 0 specifies that the syntax shall be constrained such that no triangular shape based motion compensation is used in the coded video sequence (CVS), and merge_triangle_split_dir, merge_triangle_idxO, and merge_triangle_idx1 are not present in coding unit syntax of the CVS.
  • sps_triangle_enabled_flag 1 specifies that triangular shape based motion compensation can be used in the CVS.
  • MaxNumMergeCand is derived as follows:
  • MaxNumMergeCand 6 - six_minus_max_num_merge_cand.
  • MaxNumMergeCand shall be in the range of 1 to 6, inclusive. When not present, the value of six_minus_max_num_merge_cand is inferred to be equal to
  • six_minus_max_num_merge_cand specifies the maximum number of merging MVP candidates supported in the slice subtracted from 6.
  • pps_six_minus_max_num_merge_cand_plus1 equal to 0 specifies that six_minus_max_num_merge_cand is present in a slice header of slices referring to the PPS.
  • pps_six_minus_max_num_merge_cand_plus1 is greater than 0 specifies that six_minus_max_num_merge_cand is not present in the slice header of slices referring to the picture parameter set (PPS).
  • PPS picture parameter set
  • pps_six_minus_max_num_merge_cand_plus1 shall be in the range of 0 to 6, inclusive.
  • geo_merge_idxO and geo_merge_idx1 define what MVP information is set to subblocks 1911 and 1912 of block 1910 as shown in Fig. 19 and are coded using same CABAC contexts and binarization as TPM merge indices.
  • geo_partition_idx indicates a selected partition mode (among, e.g., 64, 80, 140, etc. possibilities subject to GEO implementation) and is coded using truncated binary binarization and bypass coding.
  • geo_partition_idx is used as an index to the lookup table that stores values of a and p parameter pairs that are respectively denoted by 1921 and 1922 in Fig. 19. When GEO mode is not selected, it is possible to select the TPM.
  • the partitions of the GEO mode do not include partitions that can be obtained by TPM of binary splitting.
  • both TPM and GEO divide a block into 2 subblocks that MVP candidate indices geo_merge_idx0 and geo_merge_idx1 are assigned to.
  • Current implementations signal non-rectangular subblock partitioning and prediction related information for B and P slices, which increases signaling overhead.
  • Embodiments of the invention signal any information related to TPM, GEO and similar video coding tools, e.g. any other non-rectangular partitioning or prediction based video coding tools, only for B-slices as, for example, shown in Table 4.
  • Table 4 The proposed general slice header syntax for TPM
  • bi-directional optical flow also known as BIO
  • BIO is a sample-wise motion refinement on the top of block-wise motion compensation for“true” bi-directional prediction, which means, one of the two reference pictures is prior to the current picture in display order and the other is after the current picture 2020 in display order (Fig. 20).
  • BDOF is built on the assumption of the continuous optical flow across the time domain in the local vicinity. It is only applied to the luma component.
  • the motion vector field (v x , v y ) is determined by minimizing the difference D between the values in points A and B of the two reference pictures:
  • 1° and I 1 are the luma sample values from reference picture 0 and 1 (denoted as 2010 and 2030 in Fig. 20), respectively, after block motion compensation.
  • To and Ti denote the distances to the reference picture 0 and 1 from the current picture.
  • BDOF requires the decoder side to perform more complex operations than the traditional motion compensation. It was reported that 13 multiplications / samples are required for performing BDOF operation.
  • decoder side motion vector (MV) refinement applies to bi-predictive merge candidates.
  • MV decoder side motion vector
  • DMVR decoder side motion vector refinement
  • MV decoder side motion vector refinement
  • FIG. 21 the initial MV pair (MV0 and MV1 ) taken from reference pictures 2110 and 2130, respectively, is suggested by the selected merge candidate.
  • a pair of prediction blocks is generated by using the initial MV pair from the merge candidate.
  • a template block is generated by averaging these two prediction blocks.
  • template matching costs between the generated template block and the reference block indicated by each of the eight neighboring positions around the original MV are checked.
  • the position with a minimum cost is indicated as MVO (MV’1 ). This updated MV pair will be used to generate the final prediction signal.
  • BDOF and DMVR are mechanisms that are or can be applied to a block if and only if it is bi-predicted. Hence, if slice type does not enable bidirectional prediction, these techniques cannot be used in blocks belonging to such a slice.
  • Embodiments of the invention signal any information related to BDOF, DMVR and similar video coding tools, e.g. any other motion refinement video coding tools for bi-directional prediction, only for B-slices as, for example, shown in Table 5. Only for such slices, biprediction is provided, making it in principle possible to apply one of BDOF and DMVR or any other motion refinement video coding tool.
  • the information on the motion refinement video coding tools to be used may be provided on a slice-level basis, i.e. for example per slice and for each slice in isolation.
  • a flag may be included in a header of a slice in the encoded video sequence. This flag (or any other information on the motion refinement video coding tools) may be included in such a header by the encoder after the actual motion refinement video coding tool for encoded the blocks in the slice has been determined or obtained in any possible way.
  • the decoder may then use this information in the header (for example by parsing the header and potentially further process the obtained information on the motion refinement video coding tools) to determine which motion refinement video coding tool to use.
  • the flag may have the size of 1 bit. This is the smallest possible size for the flag but can, in some embodiments, be sufficient for encoding and providing the necessary information to the decoder.
  • Some examples how this information on the motion refinement video coding tools may be provided are given below. It is noted that the information on the motion refinement video coding tools can not only be provided in a header but also in any other format. This also includes a separate bitstream that is provided separate from the encoded video sequence, for example.
  • several flags for example at least one flag indicating whether BDOF or DMVR is to be used as motion refinement video coding tool can be provided as presented below. If a flag, like the flag sps_bdof_dmvr_slice_present_flag referred to in the above table is equal to 1 , this may specify that slice_disable_bdof_dmvr_flag is present in slice headers referring to the SPS. If the flag sps_bdof_dmvr_slice_present_flag is equal to 0, this may specify that slice_disable_bdof_dmvr_flag is not present in slice headers referring to the SPS. When sps_bdof_dmvr_slice_present_flag is not present, the value of sps_bdof_dmvr_slice_present_flag may be inferred to be equal to 0.
  • a further flag for example, a flag like slice_disable_bdof_dmvr_flag equal to 1 may specify that neither of bi-directional optical flow inter prediction and decoder motion vector refinement based inter bi-prediction is enabled in the current slice. If, on the other hand, slice_disable_bdof_dmvr_flag is equal to 0, this may specify that bi-directional optical flow inter prediction or decoder motion vector refinement based inter bi-prediction may or may not be enabled in the current slice. When slice_disable_bdof_dmvr_flag is not present, the value of slice_disable_bdof_dmvr_flag is inferred to be 0.
  • flags that can be used to provide information on the motion refinement video coding tools to be used can be obtained from the tables depicted below and referring to the respective flag-syntax.
  • semantics of the DMVR and BDOF related flags may be defined as follows.
  • sps_bdof_dmvr_slice_present_flag may be equal to 1 and this may specify that slice_disable_bdof_dmvr_flag is present in slice headers referring to the SPS.
  • sps_bdof_dmvr_slice_present_flag 0 may specify that slice_disable_bdof_dmvr_flag is not present in slice headers referring to the SPS.
  • the value of sps_bdof_dmvr_slice_present_flag is inferred to be equal to 0.
  • slice_disable_bdof_dmvr_flag 1 may alternatively specify that neither of bidirectional optical flow inter prediction and decoder motion vector refinement based inter biprediction is enabled in the current slice.
  • slice_disable_bdof_dmvr_flag 0 can specify that bi-directional optical flow inter prediction or decoder motion vector refinement based inter bi-prediction may or may not be enabled in the current slice.
  • slice_disable_bdof_dmvr_flag When slice_type is not equal to B, the value of slice_disable_bdof_dmvr_flag may be inferred to be 1. Otherwise, when slice_disable_bdof_dmvr_flag is not present, the value of slice_disable_bdof_dmvr_flag is inferred to be 0.
  • slice level is not equal to B
  • bi-prediction is not possible, making the provision of information on the motion refinement video coding tools obsolete as, for example, BDOF and DMVR cannot be used outside B-slices. In such a case, no such information may be obtained for a corresponding slice.
  • Fig. 22 shows a flow diagram of an embodiment of a method 2200 for encoding a video sequence.
  • This method 2200 is a method for encoding a video sequence using one or more motion refinement video coding tools for bi-directional prediction.
  • the method comprises the following steps, which are not intended to limit this embodiment specifically to the steps shown. Other steps may be implemented in between these steps or in addition to them.
  • the method starts with determining 2201 whether a type of a slice of the video sequence allows bi-directional inter-prediction.
  • slice-level information related to the one or more motion refinement video coding tools for bi-directional prediction is obtained 2202. This is done preferably only if the slice type allows bi-directional inter-prediction.
  • the method then proceeds to obtaining 2203 block-level level or coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction.
  • bi-directional inter-prediction is performed 2204 with motion refinement according to the slice-level and the block-level or the coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction. It is then proceeded to encoding 2205 the video by encoding at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction.
  • the slice level information related to the one or more motion refinement video coding tools for bi-directional prediction is added 2206 to a bitstream.
  • Fig. 23 shows a flow diagram of an embodiment of a method 2300 for decoding an encoded video sequence.
  • This method is a method for decoding an encoded video sequence using one or more motion refinement video coding tools for bi-directional prediction for bi-directional prediction.
  • the method comprises the following steps, which are not intended to limit this embodiment specifically to the steps shown. Other steps may be implemented in between these steps or in addition to them.
  • the method 2300 begins with obtaining 2301 slice level information related to a type of a slice of the video sequence.
  • the method then proceeds to determining 2302 whether the type of the slice of the encoded video sequence allows bi-directional inter-prediction.
  • slice-level information related to the one or more motion refinement video coding tools for bi-directional prediction is obtained 2303. This is done preferably only if the slice type allows bi-directional inter-prediction.
  • block-level or coding unit level information related to motion refinement video coding tools for bi-directional prediction is obtained 2304;
  • the method then proceeds to performing 2305 bi-directional inter-prediction of at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction according to the slice-level and block-level or coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction; and
  • the method further comprises decoding 2306 the at least one block of the video sequence by decoding the at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction.
  • Fig. 24 shows an exemplary block diagram of an encoder 2400 for encoding a video sequence using one or more motion refinement video coding tools for bi-directional prediction.
  • the encoder 2400 in this embodiment comprises a prediction unit 2401 and an encoding unit 2402.
  • the prediction unit 2401 is adapted to determine whether a type of a slice of the video sequence allows bi-directional inter-prediction.
  • the prediction unit is further adapted to obtain slice-level information related to the one or more motion refinement video coding tools for bi- directional prediction. This is preferably only done if the slice type allows bi-directional interprediction.
  • the prediction unit is adapted to further obtain block-level level or coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction and to perform bi-directional inter-prediction with motion refinement according to the slice- level and the block-level or the coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction.
  • the encoding unit 2402 is adapted to encode the video by encoding at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction.
  • the encoding unit 2402 is further adapted to add the slice level information related to the one or more motion refinement video coding tools for bi-directional prediction a bitstream.
  • Fig. 25 shows an embodiment of a decoder 2500 for decoding an encoded video sequence using one or more motion refinement video coding tools for bi-directional prediction.
  • the decoder of this embodiment comprises a receiving unit 2501 and a decoding unit 2502.
  • the receiving unit 2501 is adapted to receive the encoded video sequence and to obtain slice level information related to a type of a slice of the video sequence.
  • the receiving unit 2501 is further adapted for determining whether the type of the slice of the encoded video sequence allows bi-directional inter-prediction and to obtain slice-level information related to the one or more motion refinement video coding tools for bi-directional prediction. This is preferably only done if the slice type allows bi-directional inter-prediction.
  • the prediction unit is further adapted to obtain block-level or coding unit level information related to motion refinement video coding tools for bi-directional prediction.
  • the decoding unit 2502 is adapted to perform bi-directional inter-prediction of at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction according to the slice-level and block-level or coding unit level information related to the one or more motion refinement video coding tools for bi-directional prediction. Furthermore, the decoding unit 2502 is adapted to decode the at least one block of the video sequence by decoding the at least one block predicted using the one or more motion refinement video coding tools for bi-directional prediction.
  • Embodiments provide a method for encoding a video sequence (e.g. a coded video sequence, CVS) using motion refinement video coding tools for bi-directional prediction, wherein the method comprises:
  • a video sequence e.g. a coded video sequence, CVS
  • CVS coded video sequence
  • a type of a slice (slice type) of the video sequence (to be encoded) allows bi-directional inter-prediction (e.g. is a bi-directional inter-prediction slice or B-slice),
  • block-level e.g. coding block (CB) level or coding unit (CU) level
  • information related to motion refinement video coding tools for bi-directional prediction e.g., a flag of applying affine motion model, a weight index for bi-prediction with cu-level weights
  • inter-prediction for bi-directionally predicted block and refining motion information for
  • Embodiments provide a method for decoding a video sequence (e.g. a coded video sequence, CVS) using non-rectangular subblock partitioning and prediction, wherein the method comprises: - obtaining (explicit or implicit, e.g. by parsing a bitstream, e.g. a slice header in the bitstream related to a current slice to be decoded) slice level information related to a type of a slice of the video sequence;
  • a video sequence e.g. a coded video sequence, CVS
  • CVS coded video sequence
  • - determining whether the type of the slice (slice type) of the video sequence (to be decoded) allows bi-directional inter-prediction e.g. is a bi-directional inter-prediction slice or B-slice
  • - obtaining e.g. by parsing a bitstream, e.g. a slice header in the bitstream related to a current slice to be decoded
  • slice-level information related to motion refinement video coding tools for bi-directional prediction only if the slice type allows bi-directional inter-prediction
  • block-level e.g. coding block (CB) level or coding unit (CU) level
  • motion refinement video coding tools for bi-directional prediction e.g., a flag of applying affine motion model, a weight index for bi-prediction with cu-level weights
  • decoding the block of the video sequence by decoding the bi-directionally predicted block (e.g. by inverse transformation and dequantization of the residuals, e.g. obtained from the bitstream, and reconstructing the non-rectangular subblocks respectively the block based on the dequantized residual and the predictor obtained from the inter-prediction).
  • decoding the bi-directionally predicted block e.g. by inverse transformation and dequantization of the residuals, e.g. obtained from the bitstream, and reconstructing the non-rectangular subblocks respectively the block based on the dequantized residual and the predictor obtained from the inter-prediction.
  • Embodiments provide for an efficient encoding and/or decoding and corresponding signalling using motion refinement video coding tools for bi-directional prediction like BDOF and / or DMVR and signal related information in slice headers only for slices which allow or enable bidirectional inter-prediction, e.g. in bidirectional (B) prediction slices, also called B-slices.
  • B bidirectional prediction slices
  • the slice level information related to motion refinement video coding tools for bi-directional prediction may comprise information (e.g. a parameter, e.g. slice_disable_bdof_dmvr_flag) related to whether BDOF and DMVR are disabled for a given slice or not.
  • a parameter e.g. slice_disable_bdof_dmvr_flag
  • the method may further comprise: obtaining sequence parameter set (SPS)-level information (e.g., sps_bdof_dmvr_slice_present_flag) related to motion refinement video coding tools for bidirectional prediction; and - obtaining slice-level information related to motion refinement video coding tools for bidirectional prediction only if the sequence parameter set (SPS)-level information allows signaling slice-level flag for motion refinement video coding tools for bi-directional prediction.
  • SPS sequence parameter set
  • the sequence parameter set (SPS)-level information (e.g., sps_bdof_dmvr_slice_present_flag) related to motion refinement video coding tools for bidirectional prediction may comprise information related to whether a flag indicating that motion refinement video coding tools for bi-directional prediction (e.g., a parameter, e.g. triangle prediction/partitioning mode (TPM) and/or GEO prediction/partitioning mode) are disabled for a given slice is present in a slice level header for slices for which the sequence parameter set (SPS)-level information is relevant for; and the method may further comprise:
  • a flag indicating that motion refinement video coding tools for bi-directional prediction e.g., a parameter, e.g. triangle prediction/partitioning mode (TPM) and/or GEO prediction/partitioning mode
  • a further embodiment provides a method for video encoding, wherein bi-directional prediction is performed using motion refinement, and wherein the method comprises:
  • block-level e.g. CB or CU-level
  • C-language or C program code may, in some embodiments, be rather considered as pseudo-code, reflecting what, according to embodiments of the invention, happens, but not restricting the invention to the application of a specific programming code. Rather, embodiments may make use of the actual functions described above, independent from any specific implementation in program code and/or use of a specific programming language.
  • the first is equivalent to the 0-th
  • the second is equivalent to the 1 -th
  • L Bit-wise "exclusive or" When operating on integer arguments, operates on a two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0.
  • x y..z x takes on integer values starting from y to z, inclusive, with x, y, and z being integer numbers and z being greater than y.
  • Atan( x ) the trigonometric inverse tangent function, operating on an argument x, with an output value in the range of -TT ⁇ 2 to TT ⁇ 2, inclusive, in units of radians
  • Ceil( x ) the smallest integer greater than or equal to x.
  • Clip1 c ( x ) Clip3( 0, ( 1 « BitDepthc ) - 1 , x
  • Cos( x ) the trigonometric cosine function operating on an argument x in units of radians.
  • Round( x ) Sign( x ) * Floor( Abs( x ) + 0.5
  • Tan( x ) the trigonometric tangent function operating on an argument x in units of radians Order of operation precedence
  • the table below specifies the precedence of operations from highest to lowest; a higher position in the table indicates a higher precedence.
  • n may be described in the following manner:
  • condition 1 a 1 1 condition 1 b If( condition 1 a 1 1 condition 1 b )
  • n may be described in the following manner:
  • statement 1 If one or more of the following conditions are true, statement 1 :
  • statement 1 may be described in the following manner:
  • Embodiments, e.g. of the encoder 20 and the decoder 30, and functions described herein, e.g. with reference to the encoder 20 and the decoder 30, may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted over communication media as one or more instructions or code and executed by a hardware-based processing unit.
  • Computer-readable media may include computer-readable storage media, which
  • 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.
  • any connection is properly termed a computer-readable medium.
  • a computer-readable medium For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.
  • DSL digital subscriber line
  • 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.
  • processors such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry.
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable logic arrays
  • the term“processor,” as used herein may refer to any of the foregoing structure or any other structure suitable for 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
  • a set of ICs e.g., a chip set.
  • 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 interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

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Abstract

Des modes de réalisation de la présente invention concernent un procédé de codage d'une séquence vidéo et de décodage d'une séquence vidéo codée dans laquelle des informations de niveau de tranche associées à un ou plusieurs outils de codage vidéo d'affinement de mouvement pour une prédiction bidirectionnelle sont fournies dans le cas où la tranche est une tranche B par le codeur dans la séquence vidéo codée et ces informations sont utilisées par le décodeur pour effectuer la prédiction inter à l'aide des outils de codage vidéo d'affinement de mouvement obtenus à partir des informations. L'invention concerne en outre un codeur et un décodeur mis en oeuvre dans des modes de réalisation d'un tel procédé.
PCT/RU2020/050261 2019-10-01 2020-10-01 Procédé et appareil de signalisation de niveau de tranche pour affinement de vecteur de mouvement latéral de décodeur et de flux optique bidirectionnel WO2020251418A2 (fr)

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US11330284B2 (en) * 2015-03-27 2022-05-10 Qualcomm Incorporated Deriving motion information for sub-blocks in video coding
US10701366B2 (en) * 2017-02-21 2020-06-30 Qualcomm Incorporated Deriving motion vector information at a video decoder
CN117336504A (zh) * 2017-12-31 2024-01-02 华为技术有限公司 图像预测方法、装置以及编解码器

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