RU2781854C2 - Position-dependent combination with internal prediction with wide-angle internal prediction - Google Patents

Abstract

FIELD: video encoding and decoding.

SUBSTANCE: invention relates to video encoding and decoding, using position-depending combination with internal prediction (hereinafter – PDPC) with wide-angle internal prediction. A size of the current video data unit is determined. A mode of wide-angle internal prediction can be determined for the current unit based on the size. A prediction unit for the current unit can be determined, using the mode of wide-angle internal prediction. A prediction sample from the prediction unit can be modified in such a way that to form a modified prediction sample, using PDPC, which may include the determination of one or more reference samples, which are external for the current unit, based on the mode of wide-angle internal prediction, and modification of the prediction sample to form a modified prediction sample based on determined one or more reference samples.

EFFECT: increase in the encoding efficiency.

67 cl, 16 dwg, 1 tbl

Description

The technical field to which the invention belongs

[0001] This application relates to video encoding and decoding. In some cases, systems, equipment, methods, and computer-readable media are described for performing position-dependent intra-prediction combining (PDPC) with wide-angle intra-prediction.

State of the art

[0002] Support for digital video can be included in a wide range of devices, including digital television receivers, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-readers books, digital cameras, digital recorders, digital media players, video game devices, video game consoles, cellular or satellite radio telephones, so-called smartphones, video conferencing devices, video streaming devices, and the like. Such devices provide the ability to process and output video data for consumption. Digital video data includes large amounts of data to meet the needs of consumers and video providers. For example, video consumers want the best video quality, high fidelity, resolution, frame rates, and the like. As a result, the large amount of video data required to meet these requirements places a burden on communication networks and devices that process and store video data.

[0003] Digital video devices may implement video coding techniques to compress video data. Video coding is performed according to one or more video coding standards. For example, video coding standards include Universal Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG-2 Coding Standard Part 2 (MPEG stands for Motion Picture Expert Group) ), among others. Video coding generally uses prediction techniques (eg, inter prediction, intra prediction, and the like) that take advantage of the redundancy present in video images or sequences. An important goal of video coding technologies is to compress video data into a form that uses a lower bit rate while avoiding or minimizing video quality degradation. Due to the ever-evolving improved video transmission services, coding technologies with higher coding efficiency are required.

The essence of the invention

[0004] This document describes technologies and systems for performing position-dependent intra prediction combining (PDPC) with wide-angle modes for intra prediction. Using intra prediction, an encoding device (eg, a video encoder and/or video decoder) can generate a prediction block using spatial prediction techniques based on adjacent samples from previously encoded adjacent blocks in an identical movie frame. Adjacent samples may be identified based on the particular intra prediction mode used, such as planar mode, DC mode, and/or one of several directional prediction modes (vertical, horizontal, and various angle modes). Directional prediction modes typically use directions (or angles) from about -135 degrees to about 45 degrees relative to the vertical direction of the prediction sample.

[0005] In efficient video encoders and/or decoders, a block structure used to indicate a prediction block for intra prediction is not limited to a square (a block is square when width (w) = height (h)). The use of rectangular prediction blocks (w>h or w<h) can improve coding efficiency based on content characteristics. In such rectangular blocks, limiting the intra prediction direction to between -135 degrees and 45 degrees can lead to situations where reference samples that are further away from the prediction sample (predictive sample) are used for intra prediction instead of closer reference samples. This design decision is likely to have a negative impact on coding efficiency. It should be more advantageous to have the constraint range relaxed such that closer reference samples (eg, outside -135 to 45 degree angles) can be used for intra prediction. For example, directional prediction modes that use directions (or angles) that are less than -135 degrees or greater than 45 degrees (referred to as "wide-angle modes") relative to the vertical direction from the prediction sample.

[0006] PDPC may be used to modify predictive samples determined using intra prediction. For example, using PDPC, an encoder (eg, a video encoder and/or video decoder) may determine the reference samples that are present in one or more lines above and/or to the left of the current block and may use the reference samples to modify the predictive samples. determined using internal prediction. The modified predictive samples may then be used to encode or decode the current block.

[0007] The technologies and systems described herein provide methods for performing PDPC when wide-angle intra prediction modes are used. Techniques for signaling and/or decoding associated information are also described. In some cases, for coding, the video encoder may use modified predictive samples to determine the residuals that are signaled to the video decoder. In some cases, for decoding, the video decoder may add the modified predictive samples to the received residuals in order to reconstruct the current block.

[0008] According to at least one example, a method for decoding video data is provided. The method includes obtaining the current block of video data and determining the size of the current block. The method further includes determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The method further includes determining a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The method further includes modifying the prediction sample from the plurality of prediction samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The method further includes restoring a sample of the current block based on the modified predictive sample and the residual.

[0009] In another example, an apparatus for decoding video data is provided that includes a memory configured to store one or more prediction blocks and a video decoder comprising at least one of a fixed functional or programmable circuit. In some examples, the video decoder is configured to receive the current block of video data and determine the size of the current block. The video decoder is further configured to determine, based on the size of the current block, the wide-angle intra prediction mode to use for the current block. The video decoder is further configured to determine a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The video decoder is further configured to modify the prediction sample from the plurality of predictor samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The video decoder is further configured to resample the current block based on the modified predictive sample and the residual.

[0010] In another example, a computer-readable storage medium that stores instructions that, when executed, instructs one or more processors of a video decoding device to: obtain a current block of video data; determine the size of the current block; determine, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; determine a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of prediction samples; modify the prediction sample from the plurality of prediction samples of the prediction block to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC), wherein the modification of the prediction sample comprises: determining one or more reference samples that are external to the current block , based on the wide-angle indoor prediction mode; and modifying the predictive sample to generate a modified predictive sample based on the determined one or more reference samples; and resample the current block based on the modified predictive sample and the residual.

[0011] In another example, an apparatus for decoding video data is provided. The device includes means for obtaining the current block of video data and means for determining the size of the current block. The apparatus further includes means for determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The apparatus further includes means for determining a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The apparatus further includes means for modifying a prediction sample from a plurality of prediction samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The apparatus further includes means for restoring a sample of the current block based on the modified predictive sample and the residual.

[0012] In another example, a method for encoding video data is provided. The method includes obtaining the current block of video data and determining the size of the current block. The method further includes determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The method further includes determining a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The method further includes modifying the prediction sample from the plurality of prediction samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The method further includes determining a residual value for the residual block based on the modified predictive sample and the sample value in the current block, and signaling information indicating the residual value.

[0013] In another example, a device for encoding video data is provided that includes a memory configured to store one or more prediction blocks and a video encoder comprising at least one of a fixed functional or programmable circuit. In some examples, the video encoder is configured to receive the current block of video data and determine the size of the current block. The video encoder is further configured to determine, based on the size of the current block, the wide-angle intra prediction mode to use for the current block. The video encoder is further configured to determine a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The video encoder is further configured to modify the prediction sample from the plurality of predictor samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The video encoder is further configured to determine a residual value for the residual block based on the modified predictive sample and the sample value in the current block. The video encoder is further configured to signal information indicative of the residual value.

[0014] In another example, a computer-readable storage medium that stores instructions that, when executed, instructs one or more processors of a video encoding device to: obtain the current block of video data; determine the size of the current block; determine, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; determine a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of prediction samples; modify the prediction sample from the plurality of prediction samples of the prediction block to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC), wherein the modification of the prediction sample comprises: determining one or more reference samples that are external to the current block , based on the wide-angle indoor prediction mode; and modifying the predictive sample to generate a modified predictive sample based on the determined one or more reference samples; determining a residual value for the residual block based on the modified predictive sample and the sample value in the current block; and signaling information indicating the residual value.

[0015] In another example, a device for encoding video data is provided. The device includes means for obtaining the current block of video data and means for determining the size of the current block. The apparatus further includes means for determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The apparatus further includes means for determining a prediction block for the current block using the wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The apparatus further includes means for modifying a prediction sample from a plurality of prediction samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). Modifying the prediction sample comprises: determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode; and modifying the predictive sample to generate the modified predictive sample based on the determined one or more reference samples. The apparatus further includes means for determining a residual value for the residual block based on the modified predictive sample and the sample value in the current block. The apparatus further includes means for signaling information indicative of the residual value.

[0016] In some aspects, determining the size of the current block includes determining that the block width and block height are different sizes.

[0017] In some aspects, one or more reference samples that are external to the current block are determined using a wide-angle intra prediction mode angle relative to the predictive sample. In some examples, the wide angle intra prediction mode angle is less than -135 degrees or greater than 45 degrees with respect to the prediction sample.

[0018] In some aspects, the methods, apparatuses, and computer-readable media described above may comprise determining one or more weighting factors based on the X and Y coordinates of the predictive sample. In such aspects, modifying the predictive sample comprises modifying the predictive sample to generate a modified predictive sample based on the determined one or more reference samples, the determined one or more weights, and the predictive sample.

[0019] In some aspects, defining one or more reference samples that are external to the current block comprises defining one or more reference samples having both an X coordinate and a Y coordinate that are different from the corresponding X coordinate and Y coordinate of the prediction sample in the block. forecasting.

[0020] In some aspects, defining one or more reference samples that are external to the current block comprises: defining a row that is above the current block; determining an X coordinate in the determined row, wherein the X coordinate in the determined row is equal to the X coordinate of the prediction sample plus the Y coordinate of the prediction sample plus 1; and determining a reference sample from one or more reference samples based on the determined row and the determined x-coordinate.

[0021] In some aspects, defining one or more reference samples that are external to the current block comprises: defining a column that is to the left of the current block; determining a Y coordinate in the determined column, wherein the Y coordinate in the determined column is equal to the Y coordinate of the prediction sample plus the X coordinate of the prediction sample plus 1; and determining a reference sample from one or more reference samples based on the determined column and the determined Y coordinate.

[0022] In some aspects, defining one or more reference samples that are external to the current block comprises: defining a row that is above the current block; determining an X coordinate in the determined row, wherein the X coordinate in the determined row is based on an angle of the wide-angle intra prediction mode with respect to the prediction sample; and determining a reference sample from one or more reference samples based on the determined row and the determined X coordinate. In some cases, determining the X coordinate in the determined row comprises: determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining an X coordinate in the determined row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the prediction sample, and the Y coordinate of the prediction sample.

[0023] In some aspects, defining one or more reference samples that are external to the current block comprises: defining a column that is to the left of the current block; determining a Y coordinate in the determined column, wherein the Y coordinate in the determined column is based on an angle of the wide-angle intra prediction mode; and determining a reference sample from one or more reference samples based on the determined column and the determined Y coordinate. In some cases, determining the Y coordinate in the determined column comprises: determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining a Y coordinate in a certain column based on one of a cotangent or a tangent of an angle of the wide-angle intra prediction mode, an X coordinate of the prediction sample, and a Y coordinate of the prediction sample.

[0024] In some aspects, determining one or more reference samples that are external to the current block based on the wide-angle intra mode comprises: determining a set of one or more samples based on the wide-angle intra mode; and at least one of interpolating, rounding with a bias, or rounding without a bias of a set of one or more samples in order to generate one or more reference samples.

[0025] In some aspects, determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode , are not stored in the reference linear buffer; and determining one or more reference samples based on the last reference sample stored in the linear reference buffer.

[0026] In some aspects, modifying a prediction sample of a plurality of prediction samples of a prediction block comprises modifying a first prediction sample of the prediction block. In such aspects, one or more reference samples comprise a first set of one or more reference samples. In such aspects, the methods, apparatuses, and computer-readable media described above may comprise: determining, for a second prediction sample of a prediction block, that at least one reference sample from a second set of one or more reference samples for the second prediction sample not stored in the reference line buffer; and one of not applying the PDPC to the second predictive sample, or applying the PDPC only using the reference samples available in the linear reference buffer.

[0027] In some aspects, the wide-angle intra prediction mode is not a DC-, planar, horizontal, or vertical intra prediction mode.

[0028] In some aspects, the device for decoding video data includes a display configured to display the current block. In some aspects, the video decoding device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver, or a set-top box.

[0029] In some aspects, the device for encoding video data contains a display configured to display the current block. In some aspects, the video encoding device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver, or a set-top box.

[0030] This summary is neither intended to identify key or essential features of the claimed subject matter, nor to be used in isolation such that it defines the scope of the claimed subject matter. The subject matter of the invention is to be understood with reference to the relevant parts of the entire detailed description of this patent, any drawings and each claim.

[0031] The above, along with other features and embodiments, should become apparent upon reading the detailed description below, the claims, and the accompanying drawings.

Brief description of the drawings

[0032] Exemplary embodiments of the present application are described in detail below with reference to the following drawings:

[0033] FIG. 1 is a block diagram illustrating an exemplary video encoding and decoding system configured to implement entity disclosure technologies;

[0034] FIG. 2A and 2B are conceptual diagrams illustrating examples of DC-mode position dependent (internal) prediction combining (PDPC) weights for predictive sample positions in a 4x4 block, in accordance with some examples;

[0035] FIG. 3 is a conceptual diagram illustrating examples of intra prediction angular modes according to some examples;

[0036] FIG. 4A is a conceptual diagram illustrating an example of the up and right diagonal mode, according to some examples;

[0037] FIG. 4B is a conceptual diagram illustrating an example of a diagonal down and left mode according to some examples;

[0038] FIG. 4C is a conceptual diagram illustrating an example of the diagonal up and right adjacent mode, according to some examples;

[0039] FIG. 4D is a conceptual diagram illustrating an example of a diagonal down and left adjacent mode, according to some examples;

[0040] FIG. 5 is a conceptual diagram illustrating an example of a directional intra prediction mode according to some examples;

[0041] FIG. 6 is a conceptual diagram illustrating examples of directional intra prediction modes including wide-angle modes, according to some examples;

[0042] FIG. 7 is a conceptual diagram illustrating an example of intra prediction mode using wide-angle mode and PDPC, wherein PDPC is performed using wide-angle mode, according to some examples;

[0043] FIG. 8 is a conceptual diagram illustrating another example of intra prediction mode using wide-angle mode and PDPC, wherein PDPC is performed using wide-angle mode, according to some examples;

[0044] FIG. 9 is a flowchart illustrating an example of a process for decoding video data, in accordance with some examples;

[0045] FIG. 10 is a flowchart illustrating an example of a process for encoding video data, in accordance with some examples; and

[0046] FIG. 11 is a block diagram illustrating an example of a video encoder according to some examples; and

[0047] FIG. 12 is a block diagram illustrating an example of a video decoder according to some examples.

Detailed description of the invention

[0048] Specific aspects and embodiments of this disclosure are provided below. Some of these aspects and embodiments may be used independently, and some of them may be used in combination, as will be apparent to those skilled in the art. In the description below, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the embodiments of the application. However, it should be apparent that various embodiments may be practiced without these specific details. The drawings and description are not intended to be limiting.

[0049] The following description provides only exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the following description of exemplary embodiments should provide those skilled in the art with sufficient description to implement the exemplary embodiment. It should be understood that various changes may be made to the function and arrangement of the elements without departing from the spirit and scope of the application as set forth in the appended claims.

[0050] Video encoding devices (also referred to as "video encoders") implement video compression technologies in order to efficiently encode and decode video data. Video compression techniques may include applying various prediction modes, including spatial prediction (eg, intra-frame prediction or intra-prediction), temporal prediction (eg, inter-frame prediction or inter-prediction), inter-layer prediction (between different layers of video data), and/or other prediction technologies to reduce or remove redundancy inherent in video sequences. The video encoder may segment each movie frame of the source video sequence into rectangular regions called "video blocks" or "coding units" (described in more detail below). These video blocks may be encoded using a particular prediction mode.

[0051] Video blocks may be divided in one or more ways into one or more groups of smaller blocks. The blocks may include coding tree blocks, prediction blocks, transform blocks, and/or other suitable blocks. References, in general, to a "block", unless otherwise indicated, may refer to such video blocks (e.g., coding tree blocks, coding blocks, prediction blocks, transform blocks, or other appropriate blocks or sub-blocks, as will be understood by those skilled in the art ). Additionally, each of these units may also be referred to interchangeably herein as "units" (e.g., "coding tree unit (CTU)", "coding unit", "prediction unit (PU)", "transformation unit (TU)", etc. .P.). In some cases, a unit may indicate a logical coding unit that is encoded in the bitstream, while a block may indicate the portion of the video frame buffer that the process is targeting.

[0052] For inter-prediction modes, the video encoder may search for a block similar to the block encoded in a frame (or movie frame) located at a different temporal location called a "reference frame" or "reference movie frame". The video encoder may limit the search to a specific spatial offset from the block to be encoded. The best match can be found using a 2D motion vector that includes a horizontal displacement component and a vertical displacement component. For intra prediction modes, the video encoder may generate a predicted block using spatial prediction techniques based on data from previously encoded adjacent blocks in the same movie frame.

[0053] The video encoder may determine the prediction error. For example, the prediction may be defined as the difference between the pixel values (or sample values) in the encoded block and the predicted block. The prediction error may also be referred to as a "residual". The video encoder may also apply a transform to the prediction error (eg, a discrete cosine transform (DCT) or other suitable transform) in order to generate transform coefficients. After the transform, the video encoder may quantize the transform coefficients. The quantized transform coefficients and motion vectors may be represented using syntax elements and, along with control information, form an encoded representation of the video sequence. In some cases, the video encoder may entropy encode the syntax elements, thereby further reducing the number of bits required to represent them.

[0054] The video decoder, using the syntax elements and control information explained above, may construct predictive data (eg, a predictor block) for decoding the current frame. For example, the video decoder may sum the predicted block and the compressed prediction error. The video decoder may determine the compressed prediction error by weighting the transform basis functions using the quantized coefficients. The difference between the reconstructed frame and the original frame is called the "recovery error".

[0055] This disclosure describes systems and technologies for encoding one or more samples and/or blocks of video data using intra prediction and position-dependent combining with (intra) prediction (PDPC). For example, a wide-angle intra prediction mode may be performed in order to generate a predictive sample prediction block. The wide-angle intra prediction modes use angles outside the standard angles of -135 degrees (intra prediction mode 2) to 45 degrees (intra prediction mode 66) and may use angles that are less than -135 degrees and/or angles that are greater than 45 degrees relative to vertical direction from the predictive sample. The systems and technologies provided herein extend the use of PDPC to such wide-angle intra prediction modes in order to determine the reference samples that are used to modify the predictor samples of the predictor.

[0056] The systems and technologies described herein introduce an improvement in compression efficiency, in general, when encoding a sample and/or block of video data. For example, compression efficiency is provided by performing a PDPC approach that uses wide-angle modes, due in part to reference samples that are closer to the predictive sample used for PDPC. Compression efficiency is, in general, a desirable goal when improving the level of existing video coding technologies.

[0057] As used in this disclosure, the term "video coding" generically means either video coding or video decoding. Similarly, the term "video encoder" can generically mean a video encoder, a video decoder, or a combined video encoder/decoder (codec). In addition, certain techniques described in this disclosure regarding video decoding may also be applied to video coding, and vice versa. For example, video encoders and video decoders may be configured to perform the same process or reciprocal processes. In addition, video encoders typically perform video decoding as part of the processes of determining how to encode video data. Thus, unless otherwise noted, it should not be assumed that the technology described with respect to video decoding cannot also be performed as part of video coding, or vice versa.

[0058] This disclosure may also use terms such as "current layer", "current block", "current movie frame", "current slice", etc. In the context of this disclosure, the term "current" is intended to identify a block, movie frame, slice, etc., that is currently being encoded, e.g., as opposed to previously or already coded blocks, movie frames, and slices, or blocks, movie frames to be coded. and slices.

[0059] The techniques described herein may be applied to any of the existing video codecs (e.g., High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), or other suitable existing video codec) and/or may be an effective coding tool for any video coding standards under development and/or future video coding standards such as, for example, the Universal Video Coding (VVC) standard, the Joint Research Group Test Model (JEM) standard and/or other video coding standard under development or to be developed. Although examples are provided herein using video encoding as an illustration, in some cases, the techniques described herein may be performed using any encoding device such as an image encoder (e.g., JPEG encoder and/or decoder, etc.). etc.), a video encoder (eg, a video encoder and/or a video decoder), or other suitable encoding device.

[0060] FIG. 1 is a block diagram illustrating an exemplary video encoding and decoding system 10 that may use the techniques of this disclosure to encode one or more samples and/or blocks of video data. In some examples, video encoding and decoding system 10 may encode video data using a PDPC approach where multiple reference lines are used to generate intra-coded predictive samples and/or to generate PDPC reference samples used to modify the intra-coded predictive samples. MRL mode involves the use of multiple reference lines that are surrounded by the current block.

[0061] As shown in FIG. 1, system 10 includes a source device 12 that provides encoded video data to be subsequently decoded by a target device 14. In particular, source device 12 provides video data to a target device 14 via a computer-readable medium 16. Source device 12 and target device 14 may contain any of a wide range of devices including desktops, laptops (i.e. laptops), tablets, set-top boxes, handsets, such as so-called smartphones, televisions, cameras, display devices, digital media players , video game consoles, video streaming device, etc. In some cases, source device 12 and destination device 14 may be equipped with wireless capabilities. Thus, source device 12 and target device 14 may be wireless communication devices. Source device 12 is an exemplary video encoding device (ie, a device for encoding video data). Target device 14 is an exemplary video decoding device (eg, video decoding device or equipment).

[0062] In the example of FIG. 1, source device 12 includes a video source 18, storage media 20 configured to store video data, a video encoder 22, and an output interface 24. The target device 14 includes an input interface 26, storage media 28 configured to store encoded video data, a video decoder 30, and a display device 32. In other examples, source device 12 and target device 14 include other components or arrangements. For example, source device 12 may receive video data from an external video source such as an external camera. Likewise, target device 14 may interact with an external display device instead of including an integrated display device.

[0063] The illustrated system 10 of FIG. 1 is just one example. Techniques for processing video data may be performed by any device or equipment for encoding and/or decoding digital video. Although, in general, the techniques of this disclosure are performed by a video encoder and a video decoder, the techniques may also be performed by a video encoder/decoder, typically referred to as a "codec". Source device 12 and destination device 14 are merely examples of such encoders in which source device 12 generates encoded video data for transmission to destination device 14. In some examples, source device 12 and destination device 14 operate substantially symmetrically such that each of source device 12 and destination device 14 includes video encoding and decoding components. Therefore, system 10 can support one-way and two-way video transmission between source device 12 and destination device 14, such as for video streaming, video playback, video broadcast, or video telephony.

[0064] Video source 18 of source device 12 may include a video capture device such as a video camera, a video archive containing previously captured video, and/or a live video interface for receiving video data from a video content provider. As a further alternative, video source 18 may generate computer graphics data as source video, or a combination of live video, archived video, and computer generated video. Source device 12 may include one or more storage media (eg, storage media 20) configured to store video data. The techniques described in this disclosure may be applicable to video coding in general and may apply to wireless and/or wired applications. In each case, captured, pre-captured, or machine-generated video may be encoded by video encoder 22. Output interface 24 may output encoded video information to computer-readable medium 16.

[0065] Target device 14 may receive encoded video data to be decoded via computer readable medium 16. Computer readable medium 16 may comprise any type of media or device capable of transferring encoded video data from source device 12 to destination device 14. In some examples, computer readable medium 16 includes a communication medium for allowing source device 12 to transmit encoded video data directly to target device 14 in real time. The encoded video data may be modulated according to a communication standard, such as a wireless communication protocol, and transmitted to the target device 14. The communication medium may comprise any wireless or wired communication medium, such as radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-switched network such as a local area network, a wide area network, or a wide area network such as the Internet. The communication medium may include routers, switches, base stations, or any other equipment that may be useful in order to facilitate communication from source device 12 to destination device 14. Destination device 14 may include one or more storage media configured with the ability to store encoded video data and decoded video data.

[0066] In some examples, encoded data (eg, encoded video data) may be output from the output interface 24 to a data storage device. Similarly, the encoded data can be accessed from the data storage device via the input interface 26 . The storage device may include any of a variety of distributed or locally available storage media such as a hard drive, Blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile storage, or any other suitable digital media. data storage for storing encoded video data. In a further example, the storage device may correspond to a file server or other intermediate storage device that may store the encoded video generated by the source device 12. The destination device 14 may access the stored video data from the storage device, such as via streaming or loading. The file server may be any type of server capable of storing the encoded video data and transmitting that encoded video data to the target device 14. Exemplary file servers include a web server (eg, for a web site), an FTP server, storage devices with network connection (NAS) or local disk storage. The target device 14 may access the encoded video data over any standard data connection, including an Internet connection. It may include a wireless channel (for example, a Wi-Fi connection), a wired connection (for example, DSL, cable modem, etc.), or a combination of the above, which is suitable for accessing encoded video data stored on a file server. The transmission of the encoded video data from the storage device may be a streaming transmission, a download-based transmission, or a combination of the above.

[0067] The techniques of this disclosure may be applied to video coding in support of any of a variety of multimedia applications such as over-the-air television broadcasts, cable television, satellite television, video streaming over the Internet such as adaptive streaming technologies, including Dynamic Adaptive Streaming over HTTP (DASH), digital video that is encoded to a storage medium, decoding of digital video stored on a storage medium, or other applications. In some examples, system 10 may be configured to support one-way or two-way video in order to support applications such as video streaming, video playback, video broadcast, and/or video telephony.

[0068] Computer-readable media 16 may include volatile media such as wireless broadcast or wired network transmission, or storage media (i.e., non-volatile storage media) such as a hard drive, flash drive, CD , digital video disc, Blu-ray disc, or other machine-readable media. In some examples, a network server (not shown) may receive encoded video data from source device 12 and provide encoded video data to target device 14, such as through a network transmission. Similarly, a computing device of media manufacturing equipment, such as disc stamping equipment, may receive encoded video data from source device 12 and produce a disc containing the encoded video data. Therefore, it can be understood that the computer-readable medium 16 includes one or more computer-readable media in various forms, in various examples.

[0069] The input interface 26 of the target device 14 receives information from the computer-readable medium 16. The information of the computer-readable medium 16 may include syntax information specified by the video encoder 22 of the video encoder 22, which is also used by the video decoder 30, which includes syntax elements that describe characteristics and/or processing of blocks and other coded units, such as groups of pictures (GOPs). The storage media 28 may store the encoded video data received by the input interface 26 . The display device 32 displays the decoded video data to the user. The display device 32 may comprise any of a variety of display devices such as a cathode ray tube display (CRT), liquid crystal display (LCD), plasma display, organic light emitting diode (OLED) display, or other type of display device.

[0070] Video encoder 22 and video decoder module 30 may be implemented as any of a variety of suitable encoder or decoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs). ), discrete logic, software, hardware, firmware, or any combination of the foregoing. When the technologies are implemented in part in software, the device may store the instructions for the software on a suitable non-volatile computer-readable medium and may execute the instructions in hardware using one or more processors to implement the technologies of this disclosure. Each of video encoder 22 and video decoder 30 may be included in one or more encoders or decoders, any of which may be integrated as part of a combined encoder/decoder (codec) in a respective device.

[0071] In some examples, video encoder 22 and video decoder 30 may operate according to a video coding standard. Exemplary video coding standards include, but are not limited to, ITU-T H.261, ISO/IEC MPEG-1 Visual, ITU-T H.262, or ISO/IEC MPEG-2 Visual, ITU-T H.263, ISO/ IEC MPEG-4 Visual and ITU-T H.264 (also known as ISO/IEC MPEG-4 AVC), which includes Scalable Video Coding (SVC) and Multi-View Video Coding (MVC) extensions. "High Efficiency Video Coding (HEVC)" or "ITU-T H.265" video coding standard, including its extensions for band and screen content coding, 3D video coding (3D-HEVC) and multi-view extensions (MV-HEVC) and Scalable Extension (SHVC), developed through the Joint Video Standards Collaborative Group (JCT-VC) of the Video Coding Expert Group (VCEG) of ITU-T and the Motion Picture Expert Group (MPEG) of ISO/IEC. The latest HEVC design specification, referred to as "HEVC WD" throughout this document, is available at http://phenix.int-evry.fr/jct/doc_end_user/documents/14_Vienna/wg11/JCTVC-N1003-v1.zip.

[0072] Video encoder 22 and video decoder 30 may also operate in accordance with other proprietary or industry standards, such as the Joint Study Group Test Model (JEM) or ITU-T H.266 standard, also referred to as the "Versatile Video Coding (VVC) standard". ". The latest draft of the VVC standard is described in Bross et al. "Versatile Video Coding (Draft 4)", Joint Video Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11 13th Conference: Marrakech, MA, January 9-18, 2019, JVET-M1001-v5 (hereinafter referred to as "VVC Project 4"). However, the techniques of this disclosure are not limited to any particular coding standard.

[0073] In HEVC, VVC, and other video coding specifications, a video sequence typically includes a sequence of movie frames. Movie frames may also be referred to as "frames". The movie frame may include three arrays of samples, denoted as S _L , S _Cb and S _Cr . S _L is a two-dimensional array (ie block) of luma samples. S _Cb is a two-dimensional array of Cb-chromaticity samples. S _Cr is a two-dimensional array of Cr-chroma samples. Chroma samples may also be referred to herein as "chroma samples". A pixel may mean all three components (luminance and chrominance samples) for a given location in the movie frame array. In other cases, the movie frame may be monochrome and may include only an array of luminance samples, in which case the terms "pixel" and "sample" may be used interchangeably.

[0074] In addition, in HEVC and other video coding specifications, in order to generate an encoded representation of a movie frame, video encoder 22 may generate a set of coding tree units (CTUs). Each of the CTUs may contain a luminance sample coding tree block, two corresponding chrominance sample coding tree blocks, and syntax structures used to encode the coding tree block samples. In monochrome movie frames or movies having three separate color planes, the CTU may contain one coding tree block and syntax structures used to encode samples of the coding tree block. The coding tree block may be a block of NxN samples. A CTU may also be referred to as a "tree block" or "largest coding unit (LCU)". HEVC CTUs may be broadly similar to macroblocks in other standards such as H.264/AVC. However, the CTU is not necessarily limited to a specific size and may include one or more coding units (CUs). The slice may include an integer number of CTUs ordered sequentially in raster scan order.

[0075] When operating according to HEVC, in order to generate an encoded CTU, video encoder 22 may recursively perform quadtree segmentation on CTU coding tree blocks in order to partition coding tree blocks into coding blocks, hence the name "coding tree units". The coding block is a block of NxN samples. The CU may comprise a luminance sample coding unit and two corresponding movie chrominance sample coding units, which has an array of luma samples, an array of Cb samples, and an array of Cr samples, and syntax structures used to encode the coding block samples. In monochrome movie frames or movie frames having three separate color planes, a CU may contain one coding block and syntax structures used to encode samples of the coding block.

[0076] The syntax data in the bit stream may also specify the size for the CTU. The slice includes a certain number of consecutive CTUs in coding order. A video or movie frame may be segmented into one or more slices. As mentioned above, each treeblock may be partitioned into CUs according to the quadtree. In general, the quadtree data structure includes one node per CU, with the root node corresponding to the tree block. If the CU is split into four sub-CUs, the node corresponding to the CU includes four leaf nodes, each corresponding to one of the sub-CUs.

[0077] Each node of the quadtree data structure may provide syntax data for the corresponding CU. For example, a node in the quadtree may include a split flag indicating whether or not the CU corresponding to the node is split into sub-CUs. The syntax elements for a CU may be defined recursively and may depend on whether or not the CU is split into sub-CUs. If a CU is not split further, it is called a "CU-list". If a CU is split further, it may be generically referred to as a "CU-non-leaf". In some examples of this disclosure, the four sub-CUs of a CU-leaf may be referred to as "CU-leaves" even if there is no explicit splitting of the original CU-leaf. For example, if a 16x16 CU is not split further, the four 8x8 sub-CUs may also be referred to as "leaf CUs", although a 16x16 CU is never split.

[0078] The CU has an assignment similar to that of an H.264 macroblock, except that the CU has no size discrimination. For example, a treeblock may be broken down into four child nodes (also referred to as "sub-CUs"), and each child node may in turn be a parent node and be broken down into four more child nodes. The final unsplitted child node, called a "quadtree leaf node", contains an encoding node, also called a "CU leaf". Syntax data associated with the encoded bitstream may specify the maximum number of times a treeblock may be split, referred to as the "maximum CU depth", and may also specify a minimum size of coding nodes. Accordingly, the bitstream may also specify a smallest coding unit (SCU). This disclosure uses the term "block" to refer to any of the CUs, PUs, or TUs in the context of HEVC, or similar data structures in the context of other standards (eg, macroblocks and their subblocks in H.264/AVC).

[0079] The CU includes an encoding node, as well as prediction units (PUs) and transformation units (TUs) associated with the encoding node. The size of the CU corresponds to the size of the coding unit and, in some examples, may be square. In the HEVC example, the CU size can range from 8x8 pixels up to a treeblock size of at most 64x64 pixels or more. Each CU may contain one or more PUs and one or more TUs. Syntax data associated with a CU may describe, for example, segmentation of a CU into one or more PUs. The segmentation modes may be different between whether the CU is coded in skip mode or direct mode, coded in intra prediction mode, or coded in inter prediction mode. The PUs may be segmented such that they are non-square. Syntax data associated with a CU may also describe, for example, segmentation of the CU into one or more TUs according to a quadtree. The TU may be square or non-square (eg, rectangular) in shape.

[0080] The HEVC standard allows for transformations according to TU. TUs may differ for different CUs. The sizes of NUs are typically set based on the size of the PUs in a given CU given for a segmented LCU, although this may not always be the case. The TU is typically the same size or smaller than the PU. In some examples, the residual samples corresponding to the CU may be subdivided into smaller units using a quadtree structure, sometimes referred to as a "residual quadtree" (RQT). The leaf nodes of an RQT may be referred to as "TU". The pixel difference values associated with the TU may be transformed so as to generate transform coefficients, which may be quantized.

[0081] A CU list may include one or more PUs. In general, a PU represents a spatial region corresponding to all or part of a corresponding CU and may include data for extracting a reference sample for the PU. In addition, the PU includes prediction-related data. For example, when the PU is encoded in intra mode, data for the PU may be included in the RQT, which may include data describing the intra prediction mode for the TU corresponding to the PU. As another example, when the PU is encoded in inter-mode, the PU may include data specifying one or more motion vectors for the PU. The data defining the motion vector for the PU may describe, for example, the horizontal component of the motion vector, the vertical component of the motion vector, the resolution for the motion vector (e.g., one-quarter pixel precision or one-eighth pixel precision), the reference picture that the motion vector points to. motion, and/or a list of reference pictures (eg, list 0, list 1, or list C) for the motion vector.

[0082] A CU-list having one or more PUs may also include one or more TUs. TUs may be indicated using an RQT (also referred to as a "TU Quadtree Structure") as explained above. For example, the split flag may indicate whether or not the CU-list is split into four transform units. In some examples, each transformation unit may be split further into additional sub-TUs. When a TU is not further split, it may be referred to as a "TU-list". Generally, for intra coding, all TU leaves belonging to a CU sheet contain residual data generated from the same intra prediction mode. In other words, the same intra prediction mode is generally applied to calculate predicted values to be converted across all TUs of a CU-list. For intra coding, video encoder 22 may calculate a residual value for each TU sheet using an intra prediction mode, as a difference between the CU portion corresponding to the TU and the original block. The TU is not necessarily limited to the size of the PU. Thus, TUs may be larger or smaller than PUs. For intra coding, a PU may be co-located with a corresponding TU-list for an identical CU. In some examples, the maximum size of a TU-leaf may correspond to the size of the corresponding CU-leaf.

[0083] In addition, CU leaf TUs may also be associated with corresponding RQT structures. In other words, the CU-leaf may include a quadtree indicating how the CU-leaf is segmented into TUs. The root node of a TU quadtree generally corresponds to a CU leaf, while the root node of a CU quadtree generally corresponds to a tree block (or LCU).

[0084] As explained above, video encoder 22 may segment a coding block CU into one or more prediction blocks. A prediction block is a rectangular (ie, square or non-square) block of samples to which the same prediction is applied. The PU CU may comprise a luminance sample predictor, two corresponding chrominance sample predictors, and syntax structures used to predict the predictors. In monochrome movie frames or movie frames having three separate color planes, the PU may contain one prediction block and syntax structures used to predict the prediction block. Video encoder 22 may generate predictors (eg, luminance predictors, Cb predictors, and Cr predictors) for the predictors (luminance predictors, Cb predictors, and Cr predictors) of each CU PU.

[0085] Video encoder 22 and video decoder 30 may be configured to operate according to VVC. According to VVC, a video encoder (eg, video encoder 22) segments a frame into multiple coding tree units (CTUs). Video encoder 22 may segment the CTU according to a tree structure, such as a quadtree binary tree (QTBT) structure or a multi-type tree (MTT) structure. The QTBT framework removes the concepts of several types of segmentation, such as the division between CUs, PUs, and HEVC TUs. The QTBT structure includes two levels: a first level segmented according to quadtree segmentation and a second level segmented according to binary tree segmentation. The root node of the QTBT structure corresponds to the CTU. The leaf nodes of binary trees correspond to coding units (CUs).

[0086] In an MTT segmentation structure, blocks may be segmented using a quadtree segment (QT), a binary tree segment (BT), and one or more types of ternary tree segments (TT). A ternary tree segment is a segment in which a block is split into three subblocks. In some examples, a ternary tree segment divides a block into three subblocks without splitting the original block down the center. Segmentation types in MTT (eg, QT, BT, and TT) can be symmetrical or asymmetric.

[0087] In some examples, video encoder 22 and video decoder 30 may use a single QTBT or MTT structure to represent each of the luminance and chrominance components, while in other examples, video encoder 22 and video decoder 30 may use two or more than QTBT or MTT structures, eg one QTBT/MTT structure for the luma component and another QTBT/MTT structure for both chrominance components (or two QTBT/MTT structures for the respective chrominance components).

[0088] In VVC, a movie frame can be segmented into slices, tiles, and bricks. In general, a brick may be a rectangular area of CTU rows in a particular tile in a movie frame. A tile may be a rectangular area of the CTU in a particular column of tiles and a particular row of tiles in a movie frame. The tile column is a rectangular area of CTUs having a height equal to the height of the movie frame and a width specified by syntax elements in the movie frame parameter set. The row of tiles is a rectangular area of CTUs having a height indicated by syntax elements in the movie frame parameter set and a width equal to the width of the movie frame. In some cases, a tile may be segmented into multiple bricks, each of which may include one or more CTU rows within the tile. A tile that does not segment into multiple bricks is also called a "brick". However, a brick that is a true subset of a tile is not called a "tile". A slice can be an integer number of movie frame bricks that are contained solely in one NAL unit. In some cases, a slice may include either a certain number of full tiles, or only a rigid sequence of full bricks of a single tile.

[0089] Video encoder 22 and video decoder 30 may be configured to use quadtree segmentation according to HEVC, QTBT segmentation, MTT segmentation, or other segmentation structures. For purposes of explanation, the description of the technologies of this disclosure is provided in relation to QTBT segmentation. However, it should be understood that the techniques of this disclosure may also be applied to video encoders configured to also use quadtree segmentation or other types of segmentation.

[0090] Video encoder 22 may use intra prediction or inter prediction to generate predictive blocks for the PU. If video encoder 22 uses intra prediction to generate predictive PUs, video encoder 22 may generate predictive PUs based on decoded samples of a movie frame that includes the PU. After video encoder 22 generates predictors (eg, luma predictors, Cb predictors, and Cr predictors) for one or more PUs of one or more CU PUs, video encoder 22 may generate one or more residual blocks for the CU. For example, video encoder 22 may generate a residual luminance block for the CU. Each sample in the residual luma CU indicates a difference between a luminance sample in one of the luminance predictor blocks of the CU and a corresponding sample in the original luminance coding block CU. In addition, video encoder 22 may generate a residual Cb block for the CU. Each sample in the CU's Cb residual block may indicate a difference between a Cb sample in one of the CU's predictive Cb blocks and a corresponding sample in the CU's original Cb coding block. Video encoder 22 may also generate a residual Cr block for the CU. Each sample in the CU's residual Cr block may indicate a difference between a Cr sample in one of the predictive CU Cr blocks and a corresponding sample in the original Cr coding block of the CU.

[0091] In addition, as discussed above, video encoder 22 may use quadtree segmentation to decompose residual blocks (eg, luma residual blocks, Cb residual blocks, and Cr residual blocks) of a CU into one or more transform blocks. (for example, luminance transform blocks, Cb transform blocks and Cr transform blocks). A transform block is a rectangular (eg, square or non-square) block of samples to which an identical transform is applied. A transform unit (TU) of a CU may comprise a luminance sample transform block, two corresponding chrominance sample transform blocks, and syntax structures used to transform the transform block samples. Thus, each TU CU may have a luminance transform block, a Cb transform block, and a Cr transform block. The Luma Mapping Unit TU may be a subunit of the Residual Luma Unit CU. The Cb transform block may be a sub-block of the residual Cb block of the CU. The transform Cr block may be a subblock of the CU residual Cr block. In monochrome movie frames or movies having three separate color planes, the TU may contain one transform unit and syntax structures used to transform samples of the transform block.

[0092] Video encoder 22 may apply one or more transforms to the TU transform block in order to generate a coefficient block for the TU. For example, video encoder 22 may apply one or more transforms to the luminance transform block of the TU in order to generate the block of luminance signal coefficients for the TU. The coefficient block may be a two-dimensional array of transform coefficients. The conversion factor can be a scalar value. Video encoder 22 may apply one or more transforms to the Cb transform block of the TU in order to generate the Cb coefficient block for the TU. Video encoder 22 may apply one or more transforms to the Cr transform block of the TU in order to generate the Cr coefficient block for the TU.

[0093] In some examples, video encoder 22 skips applying transforms to the transform block. In such examples, video encoder 22 may treat the residual sample values similarly to the transform coefficients. Thus, in instances where video encoder 22 skips applying transforms, the following explanation of transform coefficients and coefficient blocks may be applicable to residual sample transform blocks.

[0094] After generating a coefficient block (eg, a luminance coefficient block, a Cb coefficient block, or a Cr coefficient block), video encoder 22 may quantize the coefficient block to possibly reduce the amount of data used to represent the coefficient block, potentially providing extra compression. Quantization, in general, means a process in which a range of values is compressed into a single value. For example, quantization can be done by dividing a value by a constant and then rounding to the nearest whole number. To quantize the coefficient block, video encoder 22 may quantize the transform coefficients of the coefficient block. After video encoder 22 quantizes the block of coefficients, video encoder 22 may entropy encode syntax elements indicating the quantized transform coefficients. For example, video encoder 22 may perform context adaptive binary arithmetic coding (CABAC) or other entropy coding techniques on syntax elements indicating quantized transform coefficients.

[0095] Video encoder 22 may output a bit stream that includes a bit sequence that forms a representation of the encoded movie frames and associated data. Thus, the bitstream contains an encoded representation of the video data. The bitstream may comprise a sequence of Network Abstraction Layer (NAL) units. A NAL unit is a syntactic structure containing an indicator as to the type of data in the NAL unit, and bytes containing that data in the form of a Primary Data Byte Sequence (RBSP), interspersed with emulation prevention bits if necessary. Each of the NAL units may include a NAL unit header and may encapsulate an RBSP. The NAL unit header may include a syntax element indicating a NAL unit type code. The NAL unit type code indicated by the NAL unit header for the NAL unit indicates the type of the NAL unit. An RBSP may be a syntax structure containing an integer number of bytes that is encapsulated in a NAL unit. In some cases, RBSP includes zero bits.

[0096] Video decoder 30 may receive a bitstream generated by video encoder 22. Video decoder 30 may decode the bitstream in order to recover movie frames of video data. As part of decoding the bitstream, video decoder 30 may parse the bitstream in order to obtain syntax elements from the bitstream. Video decoder 30 may reconstruct movie frames of video data based at least in part on syntax elements obtained from the bit stream. The process for recovering video data may generally be reciprocal to the process performed by video encoder 22. For example, video decoder 30 may use PU motion vectors to determine predictive blocks for the PUs of the current CU. In addition, video decoder 30 may inversely quantize the TU coefficient blocks of the current CU. Video decoder 30 may perform inverse transforms on the coefficient blocks in order to recover the TU transform blocks of the current CU. Video decoder 30 may recover the coding blocks of the current CU by summing the prediction block samples for the PUs of the current CU with the corresponding transform block samples of the TUs of the current CU. By recovering the coding blocks for each CU of the movie frame, video decoder 30 can recover the movie frame.

[0097] The technologies disclosed herein are based on block-based intra prediction, which is part of the video standards including AVC, HEVC, and VVC. In block-based intra prediction, typically, reference sample lines from adjacent reconstructed blocks are used to predict samples in the current block. One or more sample lines may be used for prediction. Reference samples are used through typical intra prediction modes such as DC-, planar, and angle/directional modes.

[0098] Intra prediction performs block image prediction using spatially adjacent reconstructed block image samples. In intra prediction, an NxM block (eg, 4x4) is predicted by top and left adjacent reconstructed samples (reference samples) along the selected prediction direction. As one example, a block is predicted by top and left adjacent recovered samples (ie, reference samples) along a selected prediction direction. The pivot samples are external to the block being predicted. Through the reference samples, video encoder 22 constructs a prediction block having prediction samples based on the reference samples.

[0099] In general intra prediction techniques, video encoder 22 determines a residual block indicative of differences between a prediction block and a current block (e.g., residuals indicative of differences between predictive samples and samples of the current block), and signals information indicative of residual values in the rest block. Video decoder 30 similarly determines the reference samples and constructs a prediction block. The video decoder 30 determines the residual block residuals based on the received information, and sums the residual block residuals with the prediction samples of the prediction block in order to reconstruct the current block.

[0100] As described in more detail, the exemplary techniques described in this disclosure modify one or more (eg, all) prediction samples of a prediction block. Video encoder 22 may determine residuals based on the modified predictive samples. Video decoder 30 may add the residuals with the modified predictive samples in order to reconstruct the current block.

[0101] A variety of intra prediction modes (also referred to as "intra modes") are provided. In some examples, luminance block intra prediction includes 35 modes including planar mode, DC mode, and 33 angle modes (eg, diagonal intra prediction modes and angle modes adjacent to diagonal intra prediction modes). Encoder 22 and/or decoder 30 may select a prediction mode for each block that minimizes the residual between the prediction block and the block to be encoded (e.g., based on Sum of Absolute Errors (SAE), Sum of Absolute Differences (SAD), Sum of Absolute Transformed Differences (SATD) or other measure of similarity). For example, the SAE may be calculated by considering the absolute difference between each pixel (or sample) in the block to be encoded and the corresponding pixel (or sample) in the prediction block used for comparison. The pixel (or sample) differences are summed to create a block similarity score, such as the L1-norm of the difference image, the Manhattan distance between two image blocks, or another calculation. Using the SAE as an example, the SAE for each prediction using each of the intra prediction modes indicates the absolute value of the prediction error. The intra prediction mode that has the best match with the actual current block is set by the intra prediction mode that provides the lowest SAE.

[0102] The 35 intra prediction modes are indexed as shown in Table 1 below. In other examples, more intra modes may be defined, including prediction angles that may no longer be represented by the 33 angle modes. In other examples, the prediction angles associated with the angle modes may be different from the prediction angles used in HEVC.

Internal Prediction Mode Associated name 0 INTRA_PLANAR one INTRA_DC 2...34 INTRA_ANGULAR2...INTRA_ANGULAR34

Table 1 Specification of intra prediction mode and associated names

[0103] To perform planar prediction for an NxN block, for each sample p _xy located at (x, y), a predictive sample value may be computed by applying a bilinear filter to four specific neighboring reconstructed samples (used as reference samples for intra prediction) . The four pivot samples include a top right recovery sample TR, a bottom left recovery sample BL, and two recovery samples located in the same column (r _x,-1 ) and row (r _-1,y ) of the current sample. Planar mode can be formulated as follows:

p _xy =((N-x1)*L+(N-y1)*T+x1*R+y1*B)/(2*N),

[0104] where x1=x+1, y1=y+1, R=TR and B=BL.

[0105] For the DC mode, the prediction block is filled with the average of adjacent recovered samples. Typically, planar and DC modes are used to simulate smoothly varying and constant areas of an image.

[0106] For HEVC angular intra prediction modes that include 33 different prediction directions, the intra prediction process may be described as follows. For each given angle intra prediction mode, the direction of intra prediction may be identified accordingly; for example, intra mode 18 corresponds to the pure horizontal prediction direction, and intra mode 26 corresponds to the pure vertical prediction direction. Angular prediction modes are shown in FIG. 3. In some codecs, a different number of intra prediction modes may be used. For example, in addition to planar and DC modes, 65 angle modes can be set, with mode 2 indicating a prediction direction of -135°, mode 34 indicating a prediction direction of -45°, and mode 66 indicating a prediction direction of 45°. Some codecs (eg VVC) can also specify angles beyond -135° (less than -135°) and beyond 45° (greater than 45°); these may be referred to as "wide-angle indoor modes". Although the description in this document is in relation to the design solution based on indoor modes in HEVC (ie, with 35 modes), the disclosed techniques can also be applied to a larger number of indoor modes, including wide-angle indoor modes.

[0107] The (X, Y) coordinates of each prediction block sample are projected along a particular intra prediction direction (eg, one of the angular intra prediction modes). For example, given a particular intra prediction direction, the (X, Y) coordinates of a sample of the prediction block are first projected onto a row/column of adjacent reconstructed samples along the intra prediction direction. In cases where (X, Y) is projected onto a fractional position α between two adjacent recovered samples L and R; then the predictive value for (X, Y) can be calculated using a two-tap bilinear interpolation filter, formulated as follows:

p _xy =(1-a)*L+a*R.

[0108] In order to avoid floating point operations, in HEVC, the above calculation can be approximated using integer arithmetic as follows:

p _xy =((32-')*L+a'*R+16)>>5,

[0109] where a' is an integer equal to 32*a.

[0110] In some examples, prior to intra prediction, adjacent reference samples are filtered using a 2-tap bilinear or 3-tap (1,2,1)/4-tap filter, which is known as intra-reference smoothing or mode-dependent intra-smoothing. (MDIS). When performing intra prediction, considering the intra prediction mode index (predModeIntra) and the block size (nTbS), it is determined whether or not a reference smoothing process is performed and which smoothing filter is used. The intra prediction mode index is an index indicating the intra prediction mode.

[0111] Predictive samples of the prediction block are generated using the above exemplary technologies. After the prediction samples are generated, one or more prediction samples may be modified using position dependent (internal) prediction combining (PDPC). PDPC forms are described in ITU-T SG16/Q6 Doc. COM16-C1046, "Position Dependent intra Prediction Combination (PDPC)" and in X. Zhao, V. Seregin, A. Said, M. Karczewicz "EE1 related: Simplification and extension of PDPC", 8th JVET Conference, Macao, October 2018, JVET-H0057, which are hereby actually contained in this document by reference in their entirety This document discloses the introduction of PDPC applicable to planar, DC-, horizontal and vertical modes without signaling, as summarized below.

[0112] For example, a prediction sample pred(x, y) located at (x, y) is predicted using an intra prediction mode (e.g., planar, DC, or angular) and its value is modified using a PDPC expression for one reference sample lines as follows:

pred(x, y)=(wL*R _-1,y +wT*R _x,-1- wTL*R _-1,-1 +(64-wL-wT+wTL)*pred'(x, y) +32)>>6, (equation 1)

[0113] In Equation 1, pred'(x, y) is a predictive sample value determined using the intra prediction mode as described above for generating predictive samples, and pred(x, y) is a modified value of pred'(x, y ). The terms R _x,-1 and R _-1,y represent the pivot samples above and to the left of the current sample(x, y) (adjacent top and left samples external to the current block), respectively, and the R _{-1,- 1} represents the reference sample located in the upper left corner of the current block (in the adjacent upper left corner, external to the current block). For example, as shown in FIG. 2A (described below), from the point of view of the first prediction sample 202 located in the upper left corner of block 200A, R _x,-1 represents the sample that is one line above the current block with an X coordinate identical to the X coordinate of the modified prediction sample (corresponding to value of pred'(x, y)), R _-1,y represents the sample that is one column to the left (or "left side") of the current block with a y-coordinate identical to the y-coordinate of the predictive sample being modified, and R- _{1 ,-1} represents a selection that is one column to the left of the current block and one row above the current block.

[0114] The samples (eg, reference samples used for PDPC) that are used to modify the predictive sample (generated using the intra prediction mode) are samples in the movie frame (eg, luminance and chrominance samples) and are not necessarily represent other forecast samples (although possible). For example, for a current intra prediction block that is NxM in size, video encoder 22 and/or video decoder 30 may generate an NxM size prediction block. The reference samples used to modify the predictive samples are the reference samples of the current movie frame (including the current block) and are external to the current block (in one or more blocks adjacent to the current block).

[0115] The coordinate system for identifying samples external to the current block is relative to the current block. For example, the selection located in the upper left corner of the current block has the coordinate (0, 0). Video encoder 22 may determine the residual between the prediction sample located in the upper left corner of the prediction block (eg, having coordinate (0, 0)), and the sample in the current block having coordinate (0, 0). To recover the sample located at (0, 0) in the current block, video decoder 30 may sum the prediction sample located at (0, 0) in the prediction block with the residual value corresponding to the sample located at (0, 0). Accordingly, for each sample in the current block, a corresponding sample in the prediction block (eg, having the same coordinate) is provided.

[0116] Accordingly, R _x,-1 means that the Y coordinate is -1, and therefore means a selection in the line that is above the current block. The X coordinate may be identical to the X coordinate of the predictive sample that is being modified. For R _-1,y , the x-coordinate is -1 and therefore means the column that is to the left of the current block. The Y coordinate may be identical to the Y coordinate of the predictive sample that is being modified.

[0117] It may also be possible to use a different coordinate system, such as a coordinate system in which the coordinate (0, 0) refers to the upper right sample of the movie frame. Exemplary techniques are described with respect to a coordinate system in which the coordinate (0, 0) refers to the upper left sample of the block.

[0118] For DC mode, the weights are calculated as follows for a box with dimensions width and height:

wT=32>>((y<<1)>>shift), wL=32>>((x<<1)>>shift), wTL=(wL>>4)+(wT>>4), (equation 2)

[0119] In Equation 2, shift=(log ₂ (width)+log ₂ (height)+2)>>2. For planar mode wTL=0, for horizontal mode wL=0 and wTL=wT, and for vertical mode wT=0 and wTL=wL. In some cases, PDPC weights can only be computed with sums and shifts. The value of pred(x, y) can be calculated in one step using Equation 1.

[0120] FIG. 2A is a diagram illustrating the DC mode PDPC weights (wL, wT, wTL) for the first predictive sample 202 (at sample position (0, 0)) in one 4×4 block 200A. As shown, the weight wL for the PDPC reference sample R _-1,y is 32, the weight wT for the PDPC reference sample R _x,-1 is 32, and the weight wTL for the PDPC reference sample R _-1,-1 is -4. The weights (wL, wT, wTL) may be determined according to Equation 2 above. As shown in Equation 2, the weights are determined based on the position (x, y) of the prediction sample pred(x, y) in the current block.

[0121] FIG. 2B illustrates the PDPC weights (wL, wT, wTL) in DC mode for sample position (1, 0) in one 4×4 block. As shown, the weight wL for the PDPC reference sample R _-1,y is 8, the weight wT for the PDPC reference sample R _x,-1 is 32, and the weight wTL for the PDPC reference sample R _-1,-1 equals -2. The weighting factors (wL, wT, wTL) may be determined according to Equation 2 above.

[0122] In some cases, if PDPC is applied to DC, planar, horizontal, and vertical intrinsic modes, additional edge filters are not applied, such as DC mode edge filter or horizontal/vertical mode edge filters. In some cases, Equation 1 may be generalized such that it includes additional reference sample lines (eg, not limited to samples one line above or one line to the left of the current block). In this case, multiple reference samples are available in the environments R _x,-1 , R _-1,y , R _-1,-1 , and each of them may have an assigned weight that may be optimized, for example, through training.

[0123] In some cases, PDPC can generally be extended to corner modes (eg, diagonal internal modes and corner modes that are adjacent to diagonal modes). The intended diagonal inner modes are the modes that predict according to the directions down and left and up and right, as well as several adjacent angular modes, for example, N adjacent modes between the lower left diagonal mode and the vertical mode and N or M adjacent modes between the upper right diagonal mode. mode and horizontal mode. Fig. 3 illustrates the identification of angular modes disclosed in this document. In general, adjacent modes may be a selected subset of the available angle modes. The spacing between angular modes, for example, may be non-uniform, and some angular modes, for example, may be skipped.

[0124] In some examples, video encoder 22 and video decoder 30 may be configured to perform PDPC in which the current block is intra-predicted in a corner mode that excludes DC, planar, vertical, or horizontal modes. However, technical difficulties may arise when extending PDPC to angle intra prediction modes. For example, reference samples, although located external to the current block, do not need to have identical X and/or Y coordinates with the predictive sample being modified. Therefore, it may not be clear which reference samples should be used to modify the predictive sample in such a way that video coding efficiency is achieved.

[0125] For example, if the information required to signal the residual values is reduced, an increase in bandwidth efficiency occurs. Accordingly, the PDPC reference samples used to modify the prediction block (determined using intra prediction) should be such that the residuals generated from the modified prediction block require less information to be signaled over compared to other technologies. However, if determining which reference samples to use is excessively intensive, there may be a delay in how long it takes for video decoder 30 to recover the current block.

[0126] FIG. 4A-4D illustrate the sample definitions used by PDPC extended to diagonal and adjacent angle intra modes. The dotted arrows in Fig. 4A-4D indicate the direction of prediction (eg, from FIG. 3) and are based on the reference sample used for the internally predicted predictive sample pred(x',y'). Fig. 4A illustrates the definition of the PDPC reference samples R _(x,-1) , R _(-1,y) , and R _(-1,-1) for PDPC extension to the upper right diagonal mode. The prediction sample pred(x',y') is located at (x', y') in the prediction block. The X coordinate of the reference PDPC sample R _(x,-1) is given as follows: x= x'+y'+1, and the Y coordinate of the reference PDPC sample R _(-1,y) is similarly given as follows: y=x'+y'+1. The PDPC weights for the upper right diagonal mode, for example, are: wT=16>>((y'<<1)>>shift), wL=16>>((x'<<1)>>shift), wTL=0.

[0127] FIG. 4B illustrates the definition of the reference samples R _(x,-1) , R _(-1,y) , and R _(-1,-1) for extending the PDPC to the left lower diagonal mode. The X coordinate of the reference PDPC sample R _(x,-1) is defined as: x=x'+y'+1, and the Y coordinate of the reference PDPC sample R _(-1,y) is defined as: y=x'+ y'+1. The PDPC weights for the upper right diagonal mode, for example, are: wT=16>>((y'<<1)>>shift), wL=16>>((x'<<1)>>shift), wTL=0.

[0128] In FIG. 4A and FIG. 4B, video encoder 22 and video decoder 30 may determine the line that is above the current block (eg, immediately above, but technologies are not limited to this) and determine the X coordinate in the determined line. The X coordinate in a certain row is equal to the X coordinate of the prediction sample plus the Y coordinate of the prediction sample plus 1. Video encoder 22 and video decoder 30 may determine a reference sample from one or more reference samples based on the determined row and the determined X coordinate.

[0129] Similarly, in FIG. 4A and FIG. 4B, video encoder 22 and video decoder 30 may determine the column that is to the left of the current block (eg, immediately to the left, but technologies are not limited to this) and may determine the Y coordinate in the determined column. The Y coordinate in a particular column is equal to the X coordinate of the predictive sample plus the Y coordinate of the prediction sample plus 1. Video encoder 22 and video decoder 30 may determine a reference sample from one or more reference samples based on the determined column and the determined Y coordinate.

[0130] Based on the determined X and Y coordinates, video encoder 22 and video decoder 30 may determine reference samples (eg, a first reference sample based on a certain row and a certain X coordinate and a second reference sample based on a certain column and a certain Y coordinate). Video encoder 22 and video decoder 30 may also determine weights according to the above exemplary techniques for diagonal modes (eg, right upper diagonal mode and left lower diagonal mode, as two examples). Then, based on Equation 1 (as one non-limiting example), video encoder 22 and video decoder 30 may determine a modified predictive sample (eg, pred(x, y)).

[0131] The case of adjacent right upper diagonal mode is illustrated in FIG. 4C. In general, for the angle α given in FIG. 3, the Y coordinate of the reference PDPC sample R _(-1,y) is defined as follows: y=y'+tan(α)*(x'+1), and the X coordinate of the reference PDPC sample R _(x,-1) is given as follows: x=x'+cotan(α)*(y'+1), where tan(α) and cotan(α) are the tangent and cotangent of the angle α, respectively. The PDPC weights for the adjacent right upper diagonal mode are, for example: wT=32>>((y'<<1)>>shift), wL=32>>((x'<<1)>>shift) , wTL=0 or wT=32>>((y'<<1)>>shift), wL=0, wTL=0.

[0132] Similarly, the case of adjacent left lower diagonal mode is illustrated in FIG. 4D. In general, for the angle β given in FIG. 3, the X coordinate of the reference PDPC sample R _(x,-1) is determined as follows: x=x'+tan(β)*(y'+1), and the Y coordinate of the reference PDPC sample R _(-1,y) is given by y=y'+cotan(β)*(x'+1), where tan(β) and cotan(β) are the tangent and cotangent of the angle β, respectively. The PDPC weights for the adjacent left lower diagonal mode are, for example: wL=32>>((x'<<1)>>shift), wT=32>>((y'<<1)>>shift) , wTL=0 or wL=32>>((x'<<1)>>shift), wT=0, wTL=0.

[0133] FIG. 4C and FIG. 4D, video encoder 22 and video decoder 30 may determine the line that is above the current block (eg, directly above, but technologies are not limited to this) and may determine the X coordinate in the determined line. The X coordinate in a certain row is based on the angle of the angular intra prediction mode. Video encoder 22 and video decoder 30 may determine a reference sample from one or more reference samples based on a specific row and a specific X coordinate.

[0134] In order to determine the X coordinate in a particular row, video encoder 22 and video decoder 30 may determine one of the cotangent (eg, for an adjacent right upper diagonal mode) or tangent (eg, for an adjacent left lower diagonal mode) of the corner of the angular intra prediction mode. Video encoder 22 and video decoder 30 may determine the X coordinate in a particular row based on one of the cotangent or tangent of the angle of the angular intra prediction mode, the X coordinate of the prediction sample, and the Y coordinate of the prediction sample. For example, for the adjacent right upper diagonal mode of angular intra prediction, the X coordinate in a specific row is x'+cotan(α)*(y'+1), and for the adjacent left lower diagonal mode, the X coordinate in a specific row is x'+ tan(β)*(y'+1), where x' and y' are the X and Y coordinates of the modified prediction sample.

[0135] Similarly, in FIG. 4C and FIG. 4D, video encoder 22 and video decoder 30 may determine the column that is to the left of the current block (eg, immediately to the left, but technologies are not limited to this) and may determine the Y coordinate in the determined column. The Y coordinate in a specific column is based on the angle of the angular intra prediction mode. Video encoder 22 and video decoder 30 may determine a reference sample from one or more reference samples based on a specific column and a specific Y coordinate.

[0136] In order to determine the Y coordinate in a certain column, video encoder 22 and video decoder 30 may determine one of the cotangent (eg, for adjacent left lower diagonal mode) or tangent (eg, adjacent right upper diagonal mode) of the angle of the angular intra prediction mode. Video encoder 22 and video decoder 30 may determine the Y coordinate in a certain column based on one of the cotangent or tangent of the angular intra prediction mode angle, the X coordinate of the prediction sample, and the Y coordinate of the prediction sample. For example, for the adjacent right upper diagonal mode of angular intra prediction, the Y coordinate in a certain column is y'+tan(α)*(x'+1), and for the adjacent left lower diagonal mode, the Y coordinate in a certain column is y'+ cotan(β)*(x'+1), where x' and y' are the X and Y coordinates of the modified prediction sample.

[0137] Based on the determined X and Y coordinates, video encoder 22 and video decoder 30 may determine reference samples (eg, a first reference sample based on a certain row and a certain X coordinate and a second reference sample based on a certain column and a certain Y coordinate). Video encoder 22 and video decoder 30 may also determine weights according to the above exemplary techniques for adjacent diagonal modes (eg, adjacent right upper diagonal mode and adjacent left lower diagonal mode, as two examples). Then, based on Equation 1 (as one non-limiting example), video encoder 22 and video decoder 30 may determine a modified predictive sample (eg, pred(x, y)).

[0138] As described above, PDPC can be applied to angular intra prediction modes with minimal impact on complexity. In a practical implementation, the values of tangents and cotangents of angles can be stored in tables in such a way that they are not calculated on the fly (eg, in the runtime environment). The following are exemplary tables in total for 129 angular modes:

[0139] TanAngTable[33]={0, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34 , 36, 38, 40, 42, 44, 46, 49, 52, 55, 58, 61, 64}.

[0140] CotanAngTable[33]={0, 65536, 32768, 21845, 16384, 13107, 10923, 8192, 6554, 5461, 4681, 4096, 3641, 3277, 2979, 2731, 2521, 2925 , 1820, 1725, 1638, 1560, 1489, 1425, 1337, 1260, 1192, 1130, 1074, 1024}.

[0141] The values in the tangent table indicate the location of the sample found using the intra prediction mode. The value in the tangent table indicates the location of the PDPC reference sample according to the corresponding value in the tangent table. For example, the first entry in the tangent table (indicating the location of the intra prediction sample) corresponds to the first entry in the tangent table (indicating the location of the PDPC reference sample).

[0142] In addition, the tables may already be used by angular intra block prediction and may be reused to extend PDPC to diagonal and adjacent modes (eg, angle intra prediction modes). Therefore, additional tables may not be required in a PDPC implementation. In some examples, user tables may be generated, for example, through training, with the ability to further optimize the PDPC.

[0143] In some video codecs, a block structure used to indicate a prediction block for intra prediction is not limited to a square (width w=height h). Rectangular prediction blocks (w>h or w<h) can improve coding efficiency based on content characteristics. In such rectangular blocks, limiting the intra prediction direction within the angles illustrated in FIG. 3 (-135 degrees to 45 degrees of the current block relative to the vertical direction from the prediction sample) can lead to situations where more distant reference samples are used for intra prediction instead of closer reference samples.

[0144] FIG. 5 is a diagram illustrating an example of a directional intra prediction mode in which more distant reference samples are used for intra prediction of the current block 503 of the current movie frame 502, instead of closer reference samples. The current block 503 is a rectangular block of 4×8 samples. Also shown are reference samples 506 and reference samples 508. Reference samples 506 may be a portion of one or more blocks above the current movie frame 502, and reference samples 508 may be a portion of one or more blocks to the left of the current movie frame 502.

[0145] Intra prediction is performed in order to determine the predictive sample 504 (denoted as pred(x',y')). Due to the restriction of the intra prediction direction to -135 degrees to 45 degrees (as shown in FIG. 3), closer reference samples are not used, but more distant reference samples can be used. For example, the lower left diagonal mode may be used to predict the predictive sample 504, with the angle or direction of the lower left diagonal mode illustrated by arrow 512. The upper right diagonal mode may also be used, with the angle or direction of this mode illustrated by arrow 510. Left the bottom diagonal mode may be performed at an angle of -135 degrees relative to the vertical direction from the predictive sample 504, which is the smallest bottom left angle that can be used in the range of -135 degrees to 45 degrees.

[0146] The dotted arrow 514 corresponds to an angle that is larger than the 45 degree angle used in typical intra prediction modes (in the intra prediction modes shown in FIG. 3). As shown in FIG. 5, reference sample 518 determined using a left lower diagonal model (illustrated by arrow 512) is farther from prediction sample 504 than reference sample 516 that may be determined using a wider intra angle prediction mode (illustrated by dashed arrow 514) . This design decision is likely to have an impact on coding efficiency. It should be more advantageous to have the constraint range relaxed such that closer reference samples (eg, outside of -135 to 45 degrees) can be used for prediction.

[0147] FIG. 6 is a diagram illustrating examples of directional intra prediction modes including intra prediction modes that extend beyond angles from −135 (intra prediction mode 2) to 45 degrees (intra prediction mode 66). For example, the directional intra prediction modes 67-80 and -1 to -14, illustrated by dashed arrows, may be referred to as "wide-angle intra prediction modes". It should be noted that the arrows in Fig. 6 indicate the respective reference samples used for prediction and do not indicate the direction of prediction. The prediction direction is the opposite of the direction in which the arrow is pointing. For example, the prediction direction of the intra prediction mode 68 comes from the number 68 in FIG. 6 (which is an approximate position of the reference sample used in mode 68) to the middle of the block. As noted above, PDPC may be used to modify the prediction samples determined using the intra prediction. For example, using PDPC, video encoder 22 and/or video decoder 30 may determine reference samples that are present in one or more lines above and/or to the left of the current block and may use the reference samples to modify the prediction samples determined using internal forecasting. The modified predictive samples may then be used to encode or decode the current block. However, when one or more wide-angle intra prediction modes are used, it is not clear from current video coding standards how PDPC should be applied.

[0148] This document describes systems and technologies for extending the use of PDPC to wide-angle intra prediction modes that use angles outside of standard angles from -135 degrees (mode 2) to 45 degrees (mode 66). Systems and technologies provide a practical application of video coding technologies, such as video coding technologies for PDPC, used with wide-angle intra prediction modes. For example, exemplary technologies provide a solution for using PDPC with wide-angle indoor prediction modes. Described in more detail below are exemplary ways in which video encoder 22 and video decoder 30 can perform PDPC with angle intra prediction modes.

[0149] As one example, video encoder 22 may be configured to receive the current block of video data and determine the size of the current block. For example, the width and height of the current box may be parsed to determine whether or not the current box is rectangular. In some cases, video encoder 22 may determine whether the current block is a vertically oriented block (where height > width) or a horizontally oriented block (where width > height). Video encoder 22 may determine that the wide-angle intra prediction mode is being used for the current block based on the size of the current block (eg, based on the fact that the block is rectangular). The wide-angle intra prediction mode is not a DC, planar, horizontal, or vertical intra prediction mode, and has a direction that is less than -135 degrees or greater than 45 degrees with respect to the vertical direction from each prediction sample of the prediction block.

[0150] In some cases, the angle of a diagonal extending from the bottom left position of the current block to the top left position of the current block may be used as a constraint on intra prediction mode selection, any intra prediction mode having an angle that does not exceed the diagonal may be selected. current block (from the lower left corner to the upper right corner of the block). The intra prediction mode may be selected from valid intra prediction modes based on the techniques described above. For example, a per-block intra prediction mode that minimizes the residual between the prediction block and the block to be encoded (e.g., based on sum of absolute errors (SAE), sum of absolute differences (SAD), sum of absolute transformed differences (SATD), or other measure similarity) can be selected from the allowed intra-prediction modes.

[0151] Video encoder 22 may be configured to determine a prediction block (which includes a plurality of prediction samples) for the current block based on the wide-angle intra prediction mode. Video encoder 22 may be configured to modify the prediction block prediction sample to generate a modified prediction sample using PDPC. It should be understood that while the technologies are described with respect to a single predictive sample, the exemplary technologies are not limited to this. In some examples, video encoder 22 may modify other predictor samples of the prediction block using PDPC.

[0152] To modify the predictive sample, video encoder 22 may determine one or more reference samples (PDPC reference samples) that are external to the current block based on the wide-angle intra prediction mode, and may modify the predictive sample to generate a modified predictive a sample based on the determined one or more reference samples. One or more reference samples may be identified using the direction or angle of the selected wide-angle intra prediction mode. For example, if a prediction sample is selected from a row of pixels of a neighboring block located above the current block at an angle n relative to the vertical direction from the prediction sample location, the first reference PDPC sample may be selected from a column of neighboring block pixels located to the left of the current block at an identical angle n relative to selective location. In some examples, the second PDPC reference sample may be selected from an identical sample location to the sample location used for the predictive sample. In some cases, the value from the sample location may be filtered or smoothed in order to obtain a second PDPC reference sample. In some examples, the third PDPC reference sample may be selected from a sample location in an adjacent block that is adjacent to the top left sample of the current block (eg, from the R _-1,-1 location shown in FIG. 4A). The first PDPC reference sample (and in some cases the second and/or third PDPC reference samples) may be used to modify the prediction sample in the prediction block to generate the modified prediction sample. In one illustrative example, a modified predictive sample may be determined by calculating a weighted combination (using one or more weights) of the first PDPC reference sample, the second PDPC reference sample, the third PDPC reference sample, and the predictive sample, for example, using Equation 1 above.

[0153] Video encoder 22 may determine a residual value for the residual block based on the modified predictive sample and the sample value in the current block, and may signal information indicative of the residual value.

[0154] As another example, video decoder 30 may be configured to receive the current block of video data and determine the size of the current block. For example, the width and height of the current box may be parsed to determine whether or not the current box is rectangular. In some cases, video decoder 30 may determine whether the current block is a vertically oriented block (in which height > width) or a horizontally oriented block (in which width > height). Video encoder 22 may determine that the wide-angle intra prediction mode is being used for the current block based on the size of the current block (eg, based on the fact that the block is rectangular). The wide-angle intra prediction mode is not a DC, planar, horizontal, or vertical intra prediction mode, and has a direction that is less than -135 degrees or greater than 45 degrees with respect to the vertical direction from each prediction sample of the prediction block.

[0155] Video decoder 30 may be configured to determine a prediction block that includes a plurality of prediction samples for the current block based on the wide-angle intra prediction mode. Video decoder 30 may modify the prediction block prediction sample to generate a modified prediction sample using PDPC. Similar to the above, although the technologies are described with respect to one predictive sample, the exemplary technologies are not limited to this. In some examples, video decoder 30 may modify other predictor samples of the prediction block using PDPC.

[0156] To modify the prediction sample, video decoder 30 may be configured to determine one or more reference samples that are external to the current block based on the wide-angle intra prediction mode and modify the prediction sample to generate a modified prediction sample based on the determined one or more reference samples. As described above with respect to video encoder 22, one or more reference samples may be identified using the direction or angle of the selected wide-angle intra prediction mode. For example, the first PDPC reference sample may be selected from a column or row of neighboring block pixels at an identical angle n relative to the sample location. In some examples, the second PDPC reference sample may be selected from a sample location identical to the sample location used for the predictive sample (the value of which must be filtered or smoothed in order to obtain the second PDPC reference sample) and/or the third PDPC reference sample may be selected from a sample location in an adjacent block that is adjacent to the top left sample of the current block (eg, from location R _-1,-1 shown in FIG. 4A). The first PDPC reference sample (and in some cases the second and/or third PDPC reference samples) may be used to modify the prediction sample in the prediction block to generate the modified prediction sample (eg, using Equation 1 above). Video decoder 30 may also be configured to resample the current block based on the modified predictive sample and the residual.

[0157] FIG. 7 is a diagram illustrating an example of PDPC performed with the wide-angle intra prediction mode. The current movie frame 702 is shown with the current block 703 of video data. The current block 703 is a rectangular block of 4x8 samples (eg, luma and/or chrominance component samples, or the entire set of luminance and chrominance component samples constituting a block of pixels). Also shown are neighboring reconstructed reference samples 706 and neighboring reconstructed reference samples 708. Adjacent reference samples 706 may be part of one or more blocks above the current movie frame 702, and neighboring reference samples 708 can be part of one or more blocks to the left of the current movie frame 702.

[0158] An encoder (eg, video encoder 22 and/or video decoder 30) may determine the size of the current block 703 and may determine or select an intra prediction mode to perform based on the size of the current block 703. As described above, the encoder may determine that the wide-angle intra prediction mode is used for the current block 703 based on the size of the current block 703. For example, the wide-angle intra prediction mode may be used when it is determined that the current block is a rectangular block (width and height have different sizes). In some cases, any intra prediction mode having an angle that does not exceed the diagonal of the current block 703 (from the lower left corner to the upper right corner of the block) may be selected for use in predicting the current block 703. In some cases, block size ratios may be used in order to determine the intra prediction mode to be used. For example, the block size ratio for a rectangular block can be used to determine the diagonal direction from the bottom left position to the top right position and therefore the allowed range of prediction angles (or directions).

[0159] In some examples, intra prediction modes (including modes 2-66) that are outside the diagonal corner of block 703 may be disabled, and additional wide-angle modes that are within the diagonal corner of block 703 may be made available to selection by means of an encoder. For example, for a horizontally oriented rectangular block 703 (in which width > height), if the corner associated with intra prediction mode 5 (as shown in FIG. 6) is the diagonal corner of block 703 (from the lower left corner to the upper right corner) , then modes 2, 3, and 4 may be disabled, and additional modes 67, 68, and 69 (with angles greater than 45° relative to the vertical direction from each sample location in the current block 703) may be made available for prediction of one or more prediction samples of the current prediction block. block 703.

[0160] Based on an analysis of the various available intra prediction modes (e.g., based on block size ratios, based on SAE or other similarity measure noted above, or using other suitable analysis), the encoder may select a wide-angle intra prediction mode (e.g., wide-angle intra prediction mode 67, 68, or 69) to perform intra prediction for the sample location of the current block 703. Arrow 710 in FIG. 7 indicates the prediction direction (or prediction angle) of the selected wide-angle intra prediction mode and is based on the reference sample 712 used for intra prediction of the prediction sample 704 (denoted as pred(x',y')). The wide-angle intra prediction mode illustrated in FIG. 7 is the diagonal down and left adjacent mode (for example, the wide-angle intra prediction mode 69 of FIG. 6).

[0161] Using the selected wide-angle intra prediction mode, a predictive sample 704 (pred(x',y')) may be determined for the lower right sample location in the prediction block of the current block 703. For example, a sample value 712 from adjacent reference samples 708 may be selected as a value for predictive sample 704, based on the direction (represented by arrow 710) of the selected wide-angle intra prediction mode. In some cases, the same wide-angle intra prediction mode may be used for each prediction sample of a prediction block. In some cases, a different intra prediction mode (including wide-angle modes) may be used for different prediction samples of the prediction block.

[0162] The encoder may then perform PDPC to determine one or more PDPC reference samples that are used to modify the value of the predictive sample 704. One or more PDPC reference samples may be identified using a direction (represented by an arrow). 710) of the selected wide-angle indoor prediction mode. For example, as noted above and shown in FIG. 7, a sample 712 from the row of reference samples 708 above the current block 703 is selected as the predictive sample 704 (pred(x',y')). Predictive sample 704 (pred(x',y')) is located at location (x', y') in the prediction block. The first PDPC reference sample 714 (denoted as R _(-1,y) ) is selected from a column of reference samples 706 located to the left of the current block 703 and along the identical prediction direction (given by arrow 710) of the wide-angle intra prediction mode. For the angle β shown in Fig. 7 (also shown in FIG. 3), the y-coordinate of the reference sample R _(-1,y) is defined as follows: y=y'+cotan(β)*(x'+1), where cotan(β) is the cotangent of the angle β. Examples of cotangent values are described below.

[0163] In some implementations, a second PDPC reference sample (denoted as R _(x,-1) ) may also be sampled from the same sample location 712 that was used for predictive sample 704. In such an example, the same sample value (sample value 712 ) can be used for predictive sample 704 and for second PDPC reference sample R _(x,-1) , in which case prediction sample 704 (pred(x',y')) is identical to second PDPC reference sample R _{(x, -1)} . For the angle β shown in Fig. 7, the XR coordinate _(x,-1) is defined as follows: x=x'+tan(β)*(y'+1), where tan(β) is the tangent of the angle β. Examples of tangent values are described below.

[0164] In some cases, the sample value 712 may be filtered or smoothed in order to obtain a second PDPC reference sample R _(x,-1) , in which case the value of the second PDPC reference sample R _(x,-1) should be different from the value of predictive sample 704. As noted above, predictive sample 704 (pred(x',y')) is identical to R _(x,-1) if the second reference sample R _(x,-1) is unfiltered. In some examples, the reference sample value may be filtered using intra-reference smoothing mode dependent intra-dithering (MDIS), adaptive reference sample filtering (RSAF), adaptive reference sample smoothing (ARSS), and/or other filtering technology. For example, a 2-tap bilinear filter, a 3-tap [1,2,1]/4-tap anti-aliasing filter, or other filter may be used.

[0165] In one illustrative example, sample value 712 may be filtered by a smoothing [1,2,1] filter (or other filter), and the filtered value may be used as a second reference PDPC sample R _(x,-1) . Using the 3-tap [1,2,1]/4-tap smoothing filter as an example, the outermost reference samples p[-1][2N-1] and p[2N-1][-1] are not modified (where N is the number of samples in the x and/or y direction), and all other reference samples are filtered by using two adjacent reference samples. As described in more detail below, the number of filter taps may be adapted based on the particular intra prediction mode that is selected, based on the block size, based on characteristics of one or more adjacent blocks, any combination of the above, and/or using other coefficients.

[0166] In some implementations, a third PDPC reference sample 716 (denoted R _(-1,-1) ) may be selected from an adjacent block that is adjacent to the upper left sample of the current block 703. First PDPC reference sample 714 (R _(-1,y) ), the second PDPC reference sample R _(x,-1) and the third PDPC reference samples 716 (R _(-1,-1) ) may be used to modify the predictive sample 704 (pred( x',y')) to form a modified predictive sample, which may be denoted as (pred(x, y)). For example, using Equation 1 above, the modified predictive sample pred(x, y) can be determined by calculating the weighted combination of the first PDPC reference sample 714, the second PDPC reference sample R _(x,-1) , the third PDPC reference sample 716 and predictive sample pred(x',y'). The weighting factors may be determined using the techniques described above. For example, the PDPC weights for the adjacent left lower diagonal mode are, for example: wL=32>>((x'<<1)>>shift), wT=32>>((y'<<1)>> shift), wTL=0 or wL=32>>((x'<<1)>>shift), wT=0, wTL=0.

[0167] To determine the PDPC reference sample R _(x,-1) (e.g., the second PDPC reference sample in FIG. 7), the encoder may determine a line that is above the current block (e.g., directly above or several lines above the current block 703), and may determine the X coordinate in a certain line. As noted above, the X coordinate in a specific row is based on the direction (or angle) of the wide-angle intra prediction mode, and the encoder may determine a reference sample based on the specific row and the specific X coordinate.

[0168] In order to determine the X coordinate in a certain row, the encoder may determine one of the cotangent (eg, for an adjacent right upper diagonal mode) or tangent (eg, for an adjacent left lower diagonal mode) of the wide-angle intra prediction mode angle. The encoder may determine an X coordinate in a certain row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the prediction sample, and the Y coordinate of the prediction sample. In one example, for the adjacent left lower diagonal wide-angle intra prediction mode (eg, as shown in FIG. 7), the X coordinate in a certain row is x=x'+tan(β)*(y'+1). In another example, for the adjacent right top diagonal mode, the X coordinate in a certain row is x=x'+cotan(α)*(y'+1). Here, x' and y' are the X and Y coordinates of the modified prediction sample.

[0169] Similarly, to determine the PDPC reference sample R _(-1,y) (e.g., the first PDPC reference sample 714 in FIG. 7), the encoder may determine a column that is to the left of the current block (e.g., immediately to the left of or several columns to the left of the current block 703), and may determine the Y coordinate in a particular column. As noted above, the Y coordinate in a certain column is based on the direction of the wide-angle intra prediction mode. The encoder may determine a reference sample from one or more reference samples based on a specific column and a specific Y coordinate.

[0170] In order to determine the Y coordinate in a particular column, the encoder may determine one of the cotangent (eg, for adjacent left lower diagonal mode) or tangent (eg, adjacent right upper diagonal mode) of the angular intra-angle prediction mode. The encoder may determine a Y coordinate in a certain column based on one of a cotangent or a tangent of an angle of the wide-angle intra prediction mode, an X coordinate of a prediction sample, and a Y coordinate of a prediction sample. For example, for the adjacent right upper diagonal mode of the angular intra prediction, the Y coordinate in a certain column is y'+tan(α)*(x'+1), and for the adjacent left lower diagonal mode (for example, in the example of Fig. 7) , the Y coordinate in a particular column is y'+cotan(β)*(x'+1), where x' and y' are the X and Y coordinates of the modified prediction sample.

[0171] Based on the determined X and Y coordinates, the encoder may determine PDPC reference samples (e.g., a first PDPC reference sample based on a specific row and a specific X coordinate, and a second PDPC reference sample based on a specific column and a specific Y coordinate) . The encoder may also determine weights according to the above exemplary techniques for adjacent diagonal modes (eg, adjacent right upper diagonal mode and adjacent left lower diagonal mode, as two examples). Then, based on Equation 1 (as one non-limiting example), the encoder may determine a modified predictive sample (eg, pred(x, y)).

[0172] As described above, PDPC can be applied to angular intra prediction modes with minimal impact on complexity. In a practical implementation, the values of the tangents (for example, tan(α) and/or tan(β)) and cotangents (for example, cotan(α) and/or cotan(β)) of the angles can be stored in tables in such a way that they are not calculated on the fly (for example, in a runtime environment). The following are exemplary tables for various angle modes (including wide angle modes):

[0173] TanAngTable[32]={0, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 23, 26, 29, 32, 35, 39, 45, 51 , 57, 64, 73, 86, 102, 128, 171, 256, 341, 512, 1024}.

[0174] CotanAngTable[32]={0, 8192, 4096, 2731, 2048, 1365, 1024, 819, 683, 585, 512, 455, 410, 356, 315, 282, 256, 234, 210, 182, 160 , 144, 128, 112, 95, 80, 64, 48, 32, 24, 16, 8};//(256*32)/Angle.

[0175] The values in the tangent table "TanAngTable[32]" indicate the location of the sample found using the intra prediction mode. The values in the tangent table are normalized by the value 32. For example, referring to FIG. 6, mode 66 is performed at 45 degrees (relative to the vertical direction from the center of the block) with a slope of 1, and is a prediction from the top right position to the bottom left position (the sample value from the top right is used as the predictive sample value for the sample in the middle of the block at Fig. 6). The value "32" in the tangent table corresponds to mode 66 shown in FIG. 6. The value "0" in the tangent table corresponds to the vertical mode (mode 50) shown in FIG. 6. The value "1024" corresponds to mode 80 in FIG. 6.

. Как отмечено выше, значение "0" в таблице тангенсов соответствует вертикальному режиму (режиму 50), показанному на фиг. 6. Следует отметить, что отсутствует противоположный режим относительно вертикального режима 50. Для режима 51, предусмотрен противоположный режим, который представляет собой режим -14. Режим 51 соответствует значению 1 в таблице тангенсов.[0176] The value in the tangent table "CotanAngTable[32]" indicates the location of the reference PDPC sample according to the corresponding value in the tangent table. The values in the cotant table are normalized by the value 256. For example, the first entry in the tangent table (indicating the location of the intra prediction sample) corresponds to the first entry in the tangent table (indicating the location of the PDPC reference sample). In one example, with reference to FIG. 7, if the predictive sample 704 is determined using the reference sample 712, which may have a tan table value of 35 in the tan table (the 18th position in the tan table), the second PDPC sample 714 may correspond to a tan table value of 234 (18 -th position in the table of cotangents). Cotangent matches

. As noted above, the value "0" in the tangent table corresponds to the vertical mode (mode 50) shown in FIG. 6. It should be noted that there is no reverse mode with respect to vertical mode 50. For mode 51, an opposite mode is provided, which is mode -14. Mode 51 corresponds to value 1 in the tangent table.

[0177] The example described above with respect to FIG. 7 (and the example described below with respect to FIG. 8) is for adjacent right upper wide-angle intra prediction modes. The adjacent upper right wide-angle intra prediction modes are provided as an exemplary wide-angle intra mode for which PDPC may be applied. The exemplary techniques may also extend to other angle modes, such as one or more adjacent bottom left wide-angle intra prediction modes, or other wide-angle modes. In addition, in some examples, one or more reference samples may have X and Y coordinates that are different from the X and Y coordinates of the predictive sample in the prediction block. For example, in the above exemplary equations, in order to determine the X and Y coordinates in the respective rows and columns to determine the reference samples, the X coordinate may be different from the X coordinate of the modified prediction sample, and the Y coordinate may be different from the Y coordinate of the modified prediction sample. In such cases, the pivot samples may not be in the same row or the same column as the predictive sample being modified.

[0178] As is the case for PDPC in DC-, planar, horizontal and vertical mode, there may be no additional boundary filtering, for example, as indicated in the work of authors J. Chen, E. Alshina, G. J. Sullivan, J.-R. R. Ohm, J. Boyce "Algorithm description of Joint Exploration Test Model 7", 7th JVET Conference, Torino, Italy, July 2017, JVET-G1001, for Diagonal and Adjacent Diagonal Modes when PDPC is extended to these angles modes.

[0179] In some cases, all horizontal corner modes can be converted to vertical modes by flipping the block around the bottom right diagonal. The symmetry around the vertical mode provides the ability to further reduce the number of angles to 33 with stored tangent and cotangent values in TanAngTable and CotanAngTable, respectively. For example, as described above, the value "0" in the tangent table corresponds to the vertical mode (mode 50) shown in FIG. 6. Based on the symmetry around the vertical mode, the value "0" may also correspond to the horizontal mode (mode 18) in FIG. 6. Due to the required integer precision, the values in both tables are scaled by a factor of 64 in the case of TanAngTable and a value of 1024 in the case of CotanAngTable. Multiplications in the above formulas for calculating the X and Y coordinates are prevented by accumulating table values corresponding to the angular mode as x' and y' increase while passing through the prediction block.

[0180] In some cases, the PDPC reference sample identified by the direction (or angle) of the wide-angle intra prediction mode may not correspond to an integer position of the reference sample, but may instead correspond to a fractional position (e.g., between two samples at integer positions). Fig. 8 is a diagram illustrating another example of PDPC performed using the wide mode. The current movie frame 802 includes the current block 803, which is a rectangular block of 4×8 samples. Similarly, in FIG. 7, adjacent reconstructed reference samples 806 and adjacent reconstructed reference samples 808 are also shown, which may be part of one or more blocks above and to the left, respectively, of the current movie frame 802.

[0181] An encoder (eg, video encoder 22 and/or video decoder 30) may determine the size of the current block 803 and may select an intra prediction mode to perform based on the size of the current block 803. The wide-angle intra prediction mode may be used based on determining whether that the current block is a rectangular block. For example, as described above with respect to FIG. 7, based on an analysis of the various available intra prediction modes (eg, based on SAE or other similarity measure noted above), the encoder may select a wide-angle intra-prediction mode (eg, a wide-angle -2, -3, or -4 intra prediction mode) for performing intra prediction for the sample location of the current block 803. Arrow 810 in FIG. 8 indicates the prediction direction of the selected wide-angle intra prediction mode and is based on the reference sample 814 used for intra prediction of the prediction sample 804 (denoted as pred(x',y')). The wide-angle intra prediction mode illustrated in FIG. 8 is the diagonal up and right adjacent mode (for example, the -3 wide-angle intra prediction mode of FIG. 6).

[0182] Using the direction (represented by arrow 810) of the selected wide-angle intra prediction mode, a sample value 814 from neighboring reference samples 806 may be selected as a value for predictive sample 804 (denoted as pred(x',y')) in the prediction block current block 803. The encoder may then determine one or more PDPC reference samples that are used to modify the value of the predictive sample 804. For example, using techniques similar to those described above, a first PDPC reference sample (denoted as R _(x,-1) ) and, in some cases, a second PDPC reference sample (referred to as R _(-1,y) ) and/or a third PDPC reference sample 816 (referred to as R _{(-1,-1 )} ). A third PDPC reference sample 816 (R _(-1,-1) ) may be selected from an adjacent block that is adjacent to the top left sample of the current block 803.

[0183] Predictive sample 804 (pred(x',y')) is located at location (x', y') in the prediction block. The first PDPC reference sample R _(x,-1) is selected from a row of reference samples 808 located above the current block 803 and along the identical prediction direction (given by arrow 810) of the wide-angle intra prediction mode. For the angle α shown in Fig. 8 (also shown in FIG. 3), the X coordinate of the reference sample R _(x,-1) is defined as follows: x=x'+cotan(α)*(y'+1), where cotan(α) is the cotangent of the angle a. The above describes examples of cotangent values.

[0184] The second reference PDPC sample (R _(-1,y) ) may also be sampled from the same sample location 814 that is used for the predictive sample 804. In such an example, the same sample value (sample value 814) can be used for the predictive sample 804 and for the second PDPC reference sample R _(-1,y) , in which case the predictive sample 804 (pred(x',y')) is identical to the second PDPC reference sample R _(-1,y) . As noted above, the sample value 814 may be filtered or smoothed to obtain a second PDPC reference sample R _(-1,y) , in which case the value of the second PDPC reference sample R _(-1,y) must be different from the value prediction sample 804. For the angle α shown in FIG. 8, the YR coordinate _(-1,y) is given as follows: y=y'+tan(α)*(x'+1), where tan(α) is the tangent of the angle α. Examples of tangent values are described above.

[0185] The first PDPC reference sample R _(x,-1) , the second PDPC reference sample R _(-1,y) , and the third PDPC reference samples 816 (R _(-1,-1) ) may be used to to modify the predictive sample 804 (pred(x',y')) to generate a modified predictive sample, denoted as (pred(x, y)), for example, by computing a weighted combination (for example, using the above equation 1) reference PDPC samples and predictive sample pred(x',y'). For example, the PDPC weights for the adjacent right upper diagonal mode are, for example: wT=32>>((y'<<1)>>shift), wL=32>>((x'<<1)>> shift), wTL=0 or wT=32>>((y'<<1)>>shift), wL=0, wTL=0.

[0186] As shown in FIG. 8, the first PDPC reference sample R _(x,-1) does not correspond to the integer position of the reference sample and instead is in a fractional position between two samples 812 that are in integer positions. In such a case, the PDPC reference sample R _(x,-1) may be interpolated based on the two reference samples 812. The interpolation of the reference samples 812 may be performed, for example, by linear or cubic interpolation, or rounding to the nearest neighbor node may be used if fractional values. In some cases, interpolation may be performed using an interpolation filter. For example, the interpolation filter may apply linear interpolation between two reference samples 812. In some cases, the interpolation filter and the number of taps used for the interpolation filter used to obtain the PDPC reference sample may depend on the intra prediction mode, block size (e.g., width and height), characteristics of one or more neighboring blocks (eg, whether or not a neighboring block is encoded using intra prediction), any combination of the above and/or other factors. In one illustrative example, a 6-tap Gaussian filter may be used to interpolate for certain block sizes and modes beyond 45 degrees, and a 4-tap Gaussian filter may be used for other block sizes and modes beyond -135 degrees.

[0187] Interpolation is one illustrative example of determining a reference PDPC sample that is in a fractional (non-integer) position. In some examples, the encoder (eg, video encoder 22 and/or video decoder 30) may perform at least one of interpolation, rounding with offset, and/or rounding without offset. The encoder may perform such rounding, with or without offset, based on adjacent samples in the set of one or more samples in order to generate one or more reference samples.

[0188] In some examples, clipping may be required to prevent access of reference samples outside the bounds of the reference linear buffer in case large coordinate values are being calculated. If pruning is performed, the last available reference sample may be used, or PDPC may only fall back to angular intra prediction, which is equivalent to applying zero weights for wL, wT, wTL in Equation 1, for example. For example, to determine one or more reference samples , which are external to the current block, based on the angular intra prediction mode, the encoder may be configured to determine that one or more samples external to the current block, identified based on the angular intra prediction mode, are not stored in the reference linear buffer. , and may determine one or more reference samples based on the last reference sample stored in the linear reference buffer.

[0189] In some examples, instead of using the last sample in the linear reference buffer, PDPC may be disabled for the current block, or PDPC may be disabled for certain predicted samples such that normal intra prediction (eg, without modified predictive samples) is used. As one example, for a prediction sample in a prediction block, the encoder may determine that the first reference sample is available in the reference buffer, but that the second reference sample is not available in the reference buffer. In this example, the encoder may determine that PDPC is disabled for the predictive sample. However, in some examples, the encoder may use the first reference sample for PDPC and not use the second reference sample (eg, by setting the weight for the second reference sample to zero).

[0190] In some examples, as noted above, the reference samples used for PDPC filtering may be filtered (or smoothed) by a filter (eg, a [1,2,1] filter or a stronger filter). The number of taps may be adapted based on a particular mode, block size (eg, width and height), characteristics of one or more neighboring blocks, any combination of the foregoing, and/or other factors. For example, if the intra mode indicates a wide-angle prediction mode, a stronger filter may be applied to the reference samples to obtain PDPC reference samples. In some examples, for large intra prediction distances, smoothing filtering may be applied, which removes some noise and may result in better prediction.

[0191] In some cases, the filter used for reference filtering and/or the filter used for interpolation filtering may be different for vertical reference samples (to the left of the current block) and horizontal reference samples (above the current block). In some alternatives, the decision to use different filters may depend on the block size (eg, width and height), the intra mode used for prediction, the characteristics of one or more adjacent blocks, any combination of the above, and/or other factors.

[0192] In some examples, more than one reference line from an adjacent block may be used for intra prediction and/or to determine PDPC reference samples. When more than one reference line from an adjacent block may be used for intra prediction, PDPC reference samples may be obtained for wide-angle intra prediction modes for additional reference line(s), which may be obtained by combining two or more reference lines or by selecting one or more reference lines. lines from the block's environment.

[0193] In some cases where wide-angle intra prediction is used, PDPC may be limited based on the block size, the intra mode used for prediction, characteristics of one or more adjacent blocks, any combination of the above, and/or other factors. For example, PDPC may be disabled for small blocks that are smaller than a size threshold (eg, for blocks with a width and/or height less than four pixels, eg, for 4x4 blocks).

[0194] As described above, in some examples, an encoder may perform exemplary PDPC techniques on a plurality of prediction samples in a prediction block. However, there may be cases where PDPC techniques are used for some prediction samples but not other prediction samples in the same prediction block. For example, for the first prediction sample in a prediction block, an encoder (eg, video encoder 22 and/or video decoder 30) may perform the PDPC techniques described herein. However, for the second prediction sample in the same prediction block, the reference samples required to perform PDPC techniques for the second prediction sample may not be stored in the linear reference buffer. In this example, for the second predictive sample, the encoder may not perform PDPC techniques, and normal intra prediction techniques may be used. In some cases, for the second predictive sample, it may be possible that one of the reference samples is available in the linear reference buffer and the other is not. In some examples, the encoder may not perform PDPC techniques for the second predictive sample, or may only use a reference sample that is available and assign a zero weight to weights applied to a reference sample that is not available.

[0195] FIG. 9 is a flowchart illustrating an example of a process 900 for decoding video data using one or more of the technologies described herein. At 902, process 900 includes obtaining the current block of video data. In one illustrative example, the current video block may include the video block 703 shown in FIG. 7. In another illustrative example, the current video block may include the video block 803 shown in FIG. eight.

). Как отмечено выше, диагональное направление (например, из позиции слева снизу в позицию справа сверху или из позиции слева сверху в позицию справа снизу) может использоваться для того, чтобы определять разрешенный диапазон направлений (или углов) прогнозирования.[0196] At block 904, process 900 includes determining the size of the current block. In some cases, determining the size of the current block may include determining that the block width and block height are different sizes, indicating that the block is a rectangular block. In some cases, determining the size of the current box may include determining the angle or direction of the diagonal of the current box (for example, a diagonal direction from the lower left corner of the current box to the upper right corner of the current box, or a diagonal direction from the upper left corner of the current box to the lower right corner of the current block). In some cases, the ratio of block sizes for the current block can be used to determine the diagonal direction (for example, using the Pythagorean theorem:

). As noted above, a diagonal direction (eg, bottom left position to top right position, or top left position to bottom right position) may be used to determine the permitted range of prediction directions (or angles).

[0197] At 906, process 900 includes determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The wide-angle indoor prediction mode is not a DC, planar, horizontal, or vertical indoor prediction mode. For example, the angle of the wide-angle intra prediction mode may be less than -135 degrees (for example, modes -1, -2, -3, ..., up to -14, shown in Fig. 6) or more than 45 degrees (for example, modes 67, 68, 69, ..., to 80 shown in Fig. 6) relative to the predictive sample (eg, relative to the vertical direction from the predictive sample).

[0198] As an exemplary implementation of step 906, an encoder (eg, a device for decoding video data) may determine that a wide-angle intra prediction mode can be used for the current block based on the size of the current block. For example, the wide-angle intra prediction mode may be used when it is determined that the current block is a rectangular block (width and height have different sizes). In some cases, any intra prediction mode having a direction (or angle) that does not exceed the diagonal of the current block (lower left to upper right corner of the block, or upper left to lower right corner of the block) may be selected for use in prediction. current block. In some cases, block size ratios may be used to determine which intra prediction mode should be used. For example, the block size ratio for a rectangular block can be used to determine the diagonal direction (eg, bottom left position to top right position) and therefore the allowed range of prediction directions.

[0199] In some examples, the wide-angle intra prediction mode indicator may be signaled in the bitstream. In some examples, an intra prediction mode that minimizes the residual between a prediction block and a block to be encoded (e.g., based on sum of absolute errors (SAE), sum of absolute differences (SAD), sum of absolute transformed differences (SATD), or other measure of similarity) ) can be selected to be used for the current block. Using the SAE as an illustrative example, the SAE for each prediction determined using each of the intra prediction modes indicates the absolute amount of the prediction error. The intra prediction mode that has the best match with the actual current block is set by the intra prediction mode that provides the lowest SAE. For example, process 900 may select a wide-angle intra prediction mode based on the SAE analysis, which may indicate the wide-angle intra prediction mode as the optimal mode based on the fact that the current block is rectangular.

[0200] At step 908, process 900 includes determining a prediction block for the current block using a wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. Each prediction sample may be determined using a wide-angle intra prediction mode. At 910, process 900 includes modifying a prediction sample from a plurality of prediction block prediction samples to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). For example, modifying the prediction sample may include determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode and modifying the predictive sample to generate a modified prediction sample based on the determined one or more reference samples.

[0201] In some examples, one or more reference samples that are external to the current block are determined using the angle of the wide-angle intra prediction mode relative to the predictive sample. For example, as shown in FIG. 7, the first PDPC reference sample 714 (denoted as R _(-1,y) ) and, in some cases, the second PDPC reference sample R _(x,-1) are determined along the direction (or angle) of the wide-angle intra prediction mode represented by through arrow 710.

[0202] In some cases, determining one or more reference samples that are external to the current block may include determining a row that is above the current block, determining an X coordinate in a certain row, and determining a reference sample from one or more reference samples based on a specific row and a specific x-coordinate. In such cases, the x-coordinate in a specific row is equal to the x-coordinate of the prediction sample plus the y-coordinate of the prediction sample plus 1. Additionally, in some cases, specifying one or more reference samples that are external to the current block , may include determining a row that is above the current block, determining an X coordinate in the determined row (wherein the X coordinate in the determined row is based on the angle of the wide-angle intra prediction mode relative to the predictive sample), and determining a reference sample from one or more reference samples at based on certain strings and and the specific X coordinate. For example, determining the X coordinate in the specific row may include determining one of the cotangent or tangent of the wide-angle intra prediction mode, and determining the X-coordinate in the specific row based on one of the cotangent or tangent of the wide-angle intra prediction mode, coordinate X of the predictive sample and Y coordinates of the predictive sample. In one illustrative example, with reference to FIG. 7, the second PDPC reference sample R _(x,-1) is determined from the row of adjacent reconstructed reference samples 708. The coordinate XR _(x,-1) may be determined as x=x'+tan(β)*(y'+1 ), where tan(β) is the tangent of the angle β shown in FIG. 7. In such an example, the X coordinate (x) in a particular row (eg, row 708 in FIG. 7) is equal to the X coordinate of the prediction sample (x') plus the Y coordinate of the prediction sample (y') plus 1, and is also based on the angle (on the tangent of the angle β, tan(β)) of the wide-angle intra prediction mode.

[0203] In some cases, determining one or more reference samples that are external to the current block may include determining a column that is to the left of the current block, determining the Y coordinate in the specified column, and determining a reference sample from one or more reference samples. samples based on a specific column and a specific y-coordinate. In such cases, the y-coordinate in a specific column is equal to the y-coordinate of the predictive sample plus the x-coordinate of the predictive sample plus 1. Additionally, in some cases, specifying one or more reference samples that are external to the current block may include determining a column that is to the left of the current block, determining a Y coordinate in the determined column (wherein the Y coordinate in the determined column is based on the angle of the wide-angle intra prediction mode), and determining a reference sample from one or more reference samples based on a specific column and a specific th Y coordinate. For example, determining the Y coordinate in a specific column may include determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, and determining the Y coordinate in the specific column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the predictive sample and Y coordinates of the predictive sample. In one illustrative example, with reference to FIG. 7, the first PDPC reference sample 714 (R _(-1,y) ) is determined from a column of adjacent reconstructed reference samples 706. The YR _(-1,y) coordinate may be determined as y=y'+cotan(β)*(x '+1), where cotan(β) is the cotangent of the angle β shown in FIG. 7. In such an example, the Y coordinate (y) in a particular column (eg, column 706 in FIG. 7) is equal to the Y coordinate of the predictive sample (y') plus the X coordinate of the predictive sample (x') plus 1, and is also based on the angle (on the cotangent of the angle β, cotan(β)) of the wide-angle intra prediction mode.

[0204] In some implementations, determining one or more reference samples that are external to the current block based on the wide-angle intra mode may include determining a set of one or more samples based on the wide-angle intra mode and at least one of interpolation, rounding with offset, or rounding without offset of a set of one or more samples in order to generate one or more reference samples. For example, referring to FIG. 8, interpolation may be performed on samples 812 to generate a PDPC reference sample R _(x,-1) .

[0205] In some examples, defining one or more reference samples that are external to the current block comprises defining one or more reference samples having both an X coordinate and a Y coordinate that are different from the corresponding X coordinate and Y coordinate of the prediction sample in the block forecasting. For example, as described with respect to FIG. 7, a third PDPC reference sample 716 (denoted as R _(-1,-1) ) may also be determined from an adjacent block that is adjacent to the top left sample of the current block 703.

[0206] In some implementations, determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode may include determining that one or more samples external to the current block identified based on the wide-angle mode internal prediction are not stored in the linear reference buffer. One or more reference samples may be determined based on the last reference sample stored in the line reference buffer, based on one or more samples external to the current block not stored in the line reference buffer.

[0207] In some aspects, process 900 may include determining one or more weights based on the X and Y coordinates of the predictive sample. For example, as noted above, the PDPC weights for the adjacent right upper diagonal mode may be defined as follows: wT=32>>((y'<<1)>>shift), wL=32>>((x'<< 1)>>shift), wTL=0 or wT=32>>((y'<<1)>>shift), wL=0, wTL=0. In another example, as noted above, the PDPC weights for the adjacent left lower diagonal mode may be defined as follows: wL=32>>((x'<<1)>>shift), wT=32>>((y' <<1)>>shift), wTL=0 or wL=32>>((x'<<1)>>shift), wT=0, wTL=0. The determined one or more weights may be used to modify the predictive sample along with the one or more reference samples. For example, the modified prediction sample may be generated based on the determined one or more reference samples, the determined one or more weights, and the predictive sample (eg, using Equation 1 above).

[0208] In some examples, modifying a prediction sample of a plurality of prediction samples of a prediction block may include modifying a first prediction sample of the prediction block. For example, one or more reference samples may include a first set of one or more reference samples, and process 900 may include determining, for a second predictor sample of the predictor, that at least one reference sample from the second set of one or more reference samples for the second predictive sample is not stored in the linear reference buffer. In some cases, PDPC may not be applied to the second prediction sample based on determining, for the second prediction sample, that at least one reference sample from the second set of one or more reference samples for the second prediction sample is not stored in the reference linear buffer. In some cases, PDPC may be applied to the second predictive sample using only the reference samples available in the linear reference buffer based on determining, for the second predictive sample, that at least one reference sample from the second set of one or more reference samples for the second predictive sample is not stored in the linear reference buffer.

[0209] At 912, process 900 includes resample of the current block based on the modified predictive sample and the residual. For example, as described above, the video decoding apparatus may determine a residual block residual value based on the received information, and may add the residual block residual values with the prediction samples of the prediction block in order to reconstruct the current block. The video decoding apparatus may receive information for the residual value (eg, coefficients for residual transform blocks in the bitstream) and may desample by summing the residual with a modified predictive sample (modified using PDPC) to desample the current block.

[0210] FIG. 10 is a flowchart illustrating an example of a process 1000 for encoding video data using one or more of the technologies described herein. At 1002, process 1000 includes obtaining the current block of video data. In one illustrative example, the current video block may include the video block 703 shown in FIG. 7. In another illustrative example, the current video block may include the video block 803 shown in FIG. eight.

). Как отмечено выше, диагональное направление (например, из позиции слева снизу в позицию справа сверху или из позиции слева сверху в позицию справа снизу) может использоваться для того, чтобы определять разрешенный диапазон направлений (или углов) прогнозирования.[0211] At 1004, process 1000 includes determining the size of the current block. In some cases, determining the size of the current block may include determining that the block width and block height are different sizes, indicating that the block is a rectangular block. In some cases, determining the size of the current box may include determining the angle or direction of the diagonal of the current box (for example, a diagonal direction from the lower left corner of the current box to the upper right corner of the current box, or a diagonal direction from the upper left corner of the current box to the lower right corner of the current block). In some cases, the ratio of block sizes for the current block can be used to determine the diagonal direction (for example, using the Pythagorean theorem:

). As noted above, a diagonal direction (eg, bottom left position to top right position, or top left position to bottom right position) may be used to determine the permitted range of prediction directions (or angles).

[0212] At 1006, process 1000 includes determining, based on the size of the current block, a wide-angle intra prediction mode to use for the current block. The wide-angle indoor prediction mode is not a DC, planar, horizontal, or vertical indoor prediction mode. For example, the angle of the wide-angle intra prediction mode may be less than -135 degrees (for example, modes -1, -2, -3, ..., up to -14, shown in Fig. 6) or more than 45 degrees (for example, modes 67, 68, 69, ..., to 80 shown in Fig. 6) relative to the predictive sample (eg, relative to the vertical direction from the predictive sample).

[0213] As an exemplary implementation of block 1006, an encoder (eg, a video encoder) may determine that a wide-angle intra prediction mode can be used for the current block based on the size of the current block. For example, the wide-angle intra prediction mode may be used when it is determined that the current block is a rectangular block (width and height have different sizes). In some cases, any intra prediction mode having a direction (or angle) that does not exceed the diagonal of the current block (lower left to upper right corner of the block, or upper left to lower right corner of the block) may be selected for use in prediction. current block. In some cases, block size ratios may be used to determine which intra prediction mode should be used. For example, the block size ratio for a rectangular block can be used to determine the diagonal direction (eg, bottom left position to top right position) and therefore the allowed range of prediction directions. An intra prediction mode that minimizes the residual between a prediction block and a block to be encoded (e.g., based on sum of absolute errors (SAE), sum of absolute differences (SAD), sum of absolute transformed differences (SATD), or other similarity measure) may be selected. to use for the current block. Using the SAE as an illustrative example, the SAE for each prediction determined using each of the intra prediction modes indicates the absolute amount of the prediction error. The intra prediction mode that has the best match with the actual current block is set by the intra prediction mode that provides the lowest SAE. For example, process 900 may select a wide-angle intra prediction mode based on the SAE analysis, which may indicate the wide-angle intra prediction mode as the optimal mode based on the fact that the current block is rectangular.

[0214] At 1008, process 1000 includes determining a prediction block for the current block using a wide-angle intra prediction mode. The prediction block includes a plurality of prediction samples. The prediction block includes a plurality of prediction samples. Each prediction sample may be determined using a wide-angle intra prediction mode. At 1010, process 1000 includes modifying a prediction sample from a plurality of predictor samples of the predictor to generate a modified prediction sample using position-dependent intra-prediction combining (PDPC). For example, modifying the prediction sample may include determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode and modifying the predictive sample to generate a modified prediction sample based on the determined one or more reference samples.

[0215] In some examples, one or more reference samples that are external to the current block are determined using the wide-angle intra prediction mode angle relative to the predictive sample. For example, as shown in FIG. 7, the first PDPC reference sample 714 (denoted as R _(-1,y) ) and, in some cases, the second PDPC reference sample R _(x,-1) are determined along the direction (or angle) of the wide-angle intra prediction mode represented by through arrow 710.

[0216] In some cases, determining one or more reference samples that are external to the current block may include determining a row that is above the current block, determining an X coordinate in a certain row, and determining a reference sample from one or more reference samples based on a specific row and a specific x-coordinate. In such cases, the x-coordinate in a specific row is equal to the x-coordinate of the prediction sample plus the y-coordinate of the prediction sample plus 1. Additionally, in some cases, specifying one or more reference samples that are external to the current block , may include determining a row that is above the current block, determining an X coordinate in the determined row (wherein the X coordinate in the determined row is based on the angle of the wide-angle intra prediction mode relative to the predictive sample), and determining a reference sample from one or more reference samples at based on certain strings and and the specific X coordinate. For example, determining the X coordinate in the specific row may include determining one of the cotangent or tangent of the wide-angle intra prediction mode, and determining the X-coordinate in the specific row based on one of the cotangent or tangent of the wide-angle intra prediction mode, coordinate X of the predictive sample and Y coordinates of the predictive sample. In one illustrative example, with reference to FIG. 7, the second PDPC reference sample R _(x,-1) is determined from the row of adjacent reconstructed reference samples 708. The coordinate XR _(x,-1) may be determined as x=x'+tan(β)*(y'+1 ), where tan(β) is the tangent of the angle β shown in FIG. 7. In such an example, the X coordinate (x) in a particular row (eg, row 708 in FIG. 7) is equal to the X coordinate of the prediction sample (x') plus the Y coordinate of the prediction sample (y') plus 1, and is also based on the angle (on the tangent of the angle β, tan(β)) of the wide-angle intra prediction mode.

[0217] In some cases, determining one or more reference samples that are external to the current block may include determining a column that is to the left of the current block, determining a Y coordinate in the specified column, and determining a reference sample from one or more reference samples. samples based on a specific column and a specific y-coordinate. In such cases, the y-coordinate in a specific column is equal to the y-coordinate of the predictive sample plus the x-coordinate of the predictive sample plus 1. Additionally, in some cases, specifying one or more reference samples that are external to the current block may include determining a column that is to the left of the current block, determining a Y coordinate in the determined column (wherein the Y coordinate in the determined column is based on the angle of the wide-angle intra prediction mode), and determining a reference sample from one or more reference samples based on a specific column and a specific th Y coordinate. For example, determining the Y coordinate in a specific column may include determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, and determining the Y coordinate in the specific column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the predictive sample and Y coordinates of the predictive sample. In one illustrative example, with reference to FIG. 7, the first PDPC reference sample 714 (R _(-1,y) ) is determined from a column of adjacent reconstructed reference samples 706. The YR _(-1,y) coordinate may be determined as y=y'+cotan(β)*(x '+1), where cotan(β) is the cotangent of the angle β shown in FIG. 7. In such an example, the Y coordinate (y) in a particular column (eg, column 706 in FIG. 7) is equal to the Y coordinate of the predictive sample (y') plus the X coordinate of the predictive sample (x') plus 1, and is also based on the angle (on the cotangent of the angle β, cotan(β)) of the wide-angle intra prediction mode.

[0218] In some implementations, determining one or more reference samples that are external to the current block based on the wide-angle intra mode may include determining a set of one or more samples based on the wide-angle intra mode and at least one of interpolation, rounding with offset, or rounding without offset of a set of one or more samples in order to generate one or more reference samples. For example, referring to FIG. 8, interpolation may be performed on samples 812 to generate a PDPC reference sample R _(x,-1) .

[0219] In some examples, defining one or more reference samples that are external to the current block comprises defining one or more reference samples having both an X coordinate and a Y coordinate that are different from the corresponding X coordinate and Y coordinate of the prediction sample in the block forecasting. For example, as described with respect to FIG. 7, a third PDPC reference sample 716 (denoted as R _(-1,-1) ) may also be determined from an adjacent block that is adjacent to the top left sample of the current block 703.

[0220] In some implementations, determining one or more reference samples that are external to the current block based on the wide-angle intra prediction mode may include determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode internal prediction are not stored in the linear reference buffer. One or more reference samples may be determined based on the last reference sample stored in the line reference buffer, based on one or more samples external to the current block not stored in the line reference buffer.

[0221] In some aspects, process 900 may include determining one or more weights based on the X and Y coordinates of the predictive sample. For example, as noted above, the PDPC weights for the adjacent right upper diagonal mode may be defined as follows: wT=32>>((y'<<1)>>shift), wL=32>>((x'<< 1)>>shift), wTL=0 or wT=32>>((y'<<1)>>shift), wL=0, wTL=0. In another example, as noted above, the PDPC weights for the adjacent left lower diagonal mode may be defined as follows: wL=32>>((x'<<1)>>shift), wT=32>>((y' <<1)>>shift), wTL=0 or wL=32>>((x'<<1)>>shift), wT=0, wTL=0. The determined one or more weights may be used to modify the predictive sample along with the one or more reference samples. For example, the modified prediction sample may be generated based on the determined one or more reference samples, the determined one or more weights, and the predictive sample (eg, using Equation 1 above).

[0222] In some examples, modifying a prediction sample of a plurality of prediction samples of a prediction block may include modifying a first prediction sample of the prediction block. For example, one or more reference samples may include a first set of one or more reference samples, and process 900 may include determining, for a second predictor sample of the predictor, that at least one reference sample from the second set of one or more reference samples for the second predictive sample is not stored in the linear reference buffer. In some cases, PDPC may not be applied to the second prediction sample based on determining, for the second prediction sample, that at least one reference sample from the second set of one or more reference samples for the second prediction sample is not stored in the reference linear buffer. In some cases, PDPC may be applied to the second predictive sample using only the reference samples available in the linear reference buffer based on determining, for the second predictive sample, that at least one reference sample from the second set of one or more reference samples for the second predictive sample is not stored in the linear reference buffer.

[0223] At 1012, process 1000 includes determining a residual value for the residual block based on the modified predictive sample and the sample value in the current block. For example, the residual value may include the difference (or error) between the modified predictive sample and the sample value in the current block. A transform block (eg, TU, TB, etc.) with residuals and/or transform coefficients may be generated based on one or more residuals determined for the current block. For example, the residual data may be transformed from a pixel region to a transformation region, resulting in residual transformation coefficients. The residual transform coefficients may be quantized, and in some cases, entropy encoding may be applied to the quantized transform coefficients. At 1014, process 1000 includes signaling information indicative of a residual value. The information may include a residual transform block (which may be entropy encoded), residual transform coefficients, quantized residual transform coefficients, or entropy encoded quantized residual transform coefficients.

[0224] In some examples, processes 900 and 1000 may be performed by a computing device or equipment. For example, process 900 may be performed by video decoder 30, or by a video decoding device or equipment (eg, camera, computer, mobile device, broadcast receiver, or set-top box) that includes video decoder 30. In another example, process 1000 may be performed via video encoder 22 or via a device or equipment (for example, a camera, computer, mobile device, broadcast receiver, or set-top box) for encoding video data, which includes video encoder 22. In some cases, the computing device or equipment may include a processor, a microprocessor, microcomputer, or other device component that is configured to perform the steps of one or both of processes 900 and 1000. In some examples, a computing device or equipment may include one or more components, such as one or more cameras for capturing one or more images, an input device (for example, a touch screen interface, a keypad, a mouse, or other input device), an output device (for example, a display for displaying the current block, one or more images, notifications, and/or other display data, audio output speaker, or other output device), any combination of the above, or other suitable component. In some examples, the computing device may include a desktop computer, a laptop (i.e., laptop) computer, a tablet computer, a set-top box, a handset such as a so-called smartphone, a television receiver, a camera, a display device, a digital media player, video game console, video streaming device, wearable device, etc. or another device with one or more components. In some cases, the computing device may include a video codec. In some examples, some of the one or more components may be separate from the computing device, in which case the computing device receives data or transmits data. The computing device may further include a network interface configured to communicate. The network interface may be configured to exchange Internet Protocol (IP) based data or other suitable network data.

[0225] Components of a computing device (eg, one or more processors, one or more microprocessors, one or more microcomputers, and/or other component) may be implemented in circuitry. For example, components may include and/or be implemented using electronic circuits or other electronic hardware, which may include one or more programmable electronic circuits (e.g., microprocessors, graphics processing units (GPUs), digital signal processors (DSPs) , central processing units (CPUs), and/or other suitable electronic circuitry), and/or may include and/or be implemented using computer software, firmware, or any combination of the foregoing in order to perform the various operations described herein. .

[0226] Processes 900 and 1000 are illustrated as a logical flow diagram, the operation of which is a sequence of operations that may be implemented in hardware, computer instructions, or a combination of the above. In the context of computer instructions, operations are computer-executable instructions stored on one or more computer-readable storage media that, when executed by one or more processors, perform the recited operations. In general, computer-executable instructions include procedures, programs, objects, components, data structures, and the like that perform specific functions or implement specific data types. The order in which the operations are described is not to be construed as a limitation, and any number of the described operations may be combined in any order and/or in parallel to implement the processes.

[0227] Additionally, processes 900 and 1000 may run under the control of one or more computer systems configured with executable instructions, and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) executing together on one or more processors, through hardware, or a combination of the foregoing. As noted above, the code may be stored on a computer-readable or machine-readable storage medium, for example, in the form of a computer program containing a plurality of instructions executable by one or more processors. The computer-readable or machine-readable storage medium may be non-volatile.

[0228] FIG. 11 is a block diagram illustrating an exemplary video encoder 22 that may implement the techniques of this disclosure. Fig. 11 is provided for purposes of explanation and should not be considered a limitation of the technologies as illustrated and outlined in this disclosure. The techniques of this disclosure may be applicable to various standards or encoding methods.

[0229] In the example of FIG. 11, the video encoder 22 includes a prediction processing unit 100, a video memory 98, a residual generating unit 102, a transform processing unit 104, a quantization unit 106, an inverse quantization unit 108, an inverse transform processing unit 110, a reconstruction unit 112, a filtering unit 114, a decoded movie frame buffer 116; and an entropy encoding module 118. The prediction processing unit 100 includes an inter prediction processing unit 120 and an intra prediction processing unit 126 . The inter prediction processing unit 120 may include a motion estimation unit and a motion compensation unit (not shown).

[0230] The video data storage device 101 may be configured to store video data to be encoded by the components of the video encoder 22. The video data stored in the video data storage device 101 may be obtained from a video source 18, for example. reference movie frames that stores reference video data for use in encoding video data by video encoder 22, such as in intra- or inter-coding modes. The video data memory 101 and the decoded movie frame buffer 116 may be formed by any of a plurality of memories such as dynamic random access memory (DRAM) including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM) or other types of storage devices. The video data storage 101 and the decoded movie frame buffer 116 may be provided by an identical storage device or separate storage devices. In various examples, video memory 101 may be on-chip with other components of video encoder 22 or off-chip with respect to these components. The video storage device 101 may be identical to or be part of the storage media 20 of FIG. one.

[0231] Video encoder 22 receives video data. Video encoder 22 may encode each CTU in a slice of a video frame. Each of the CTUs may be associated with luminance CTBs of the same size and corresponding movie CTBs. As part of CTU coding, prediction processing unit 100 may perform segmentation in order to partition CTB CTUs into progressively smaller blocks. The smaller blocks may be CU coding blocks. For example, the prediction processing module 100 may segment the CTB associated with the CTU according to a tree structure. In accordance with one or more techniques of this disclosure, for each respective non-leaf node of the tree structure, at each depth level of the tree structure, a plurality of allowed split patterns for the corresponding non-leaf node are provided, and the video block corresponding to the corresponding non-leaf node is segmented into video blocks, corresponding to the child nodes of the corresponding non-leaf node, according to one of the set of valid partition patterns. In one example, prediction processing module 100 or another processing module of video encoder 22 may be configured to perform any combination of the technologies described herein.

[0232] Video encoder 22 may encode the CTU CUs in order to generate encoded CU representations (ie, encoded CUs). As part of CU encoding, prediction processing unit 100 may segment coding units associated with a CU between one or more CU PUs. In accordance with the techniques of this disclosure, a CU may include only one PU. Thus, in some examples of this disclosure, the CU is not divided into individual prediction blocks, but instead, the prediction process is performed on the entire CU. Thus, each CU may be associated with a luminance predictor and corresponding chrominance predictors. Video encoder 22 and video decoder 30 may support CUs having different sizes. As mentioned above, the size of the CU may mean the size of the luminance coding block of the CU as well as the size of the luminance prediction block. As explained above, video encoder 22 and video decoder 30 may support CU sizes defined by any combination of the exemplary segmentation technologies described herein.

[0233] The inter prediction processing unit 120 may generate prediction data for the PU by performing inter prediction for each PU of the CU. As explained herein, in some examples of this disclosure, a CU may contain only one PU, ie. CU and PU may be synonymous. Predictive data for the PU may include predictive blocks of the PU and motion information for the PU. The inter prediction processing unit 120 may perform different operations for a PU or a CU depending on whether the PU is in an I-slice, a P-slice, or a B-slice. In the I-slice, all PUs are internally predicted. Therefore, if the PU is in an I-slice, the inter prediction processing unit 120 does not perform inter prediction for the PU. Thus, for blocks encoded in I-mode, a predicted block is generated using spatial prediction from previously encoded adjacent blocks in the same frame. If the PU is in a P-slice, the inter prediction processing unit 120 may use unidirectional inter prediction to generate a PU predictor. If the PU is in a B-slice, the inter prediction processing unit 120 may use unidirectional or bidirectional inter prediction to generate a PU predictor.

[0234] The intra prediction processing unit 126 may generate prediction data for the PU by performing intra prediction for the PU. Prediction data for a PU may include PU predictors and various syntax elements. Intra prediction processing unit 126 may perform intra prediction for PUs in I-slices, P-slices, and B-slices.

[0235] In order to perform intra prediction for the PU, the intra prediction processing unit 126 may use multiple intra prediction modes to generate multiple sets of prediction data for the PU. Intra prediction processing unit 126 may use samples from neighbor PU sample blocks to generate a prediction block for the PU. Neighboring PUs may be above, above and to the right, above and to the left, or to the left of the PU, subject to the encoding order from left to right, top to bottom for PUs, CUs, and CTUs. The intra prediction processing unit 126 may use various numbers of intra prediction modes, for example, 33 directional intra prediction modes. In some examples, the number of intra prediction modes may depend on the size of the region associated with the PU.

[0236] In one example, the intra prediction processing module 126 may be configured to implement entity disclosure technologies. In other examples, other blocks or modules may be configured to implement all or some of the entity disclosure technologies.

[0237] The prediction processing unit 100 may select prediction data for the CU PU from among prediction data generated by the PU mutual prediction processing unit 120 or prediction data generated by the PU intra prediction processing unit 126 . In some examples, the prediction processing unit 100 selects prediction data for the CU PU based on the distortion metrics depending on the transmission rate of the prediction data sets. The predictor blocks of the selected predictor data may be referred to herein as "selected predictor blocks".

[0238] Residue generator 102 may generate, based on coding blocks (eg, luminance coding blocks, Cb coding blocks, and Cr coding blocks) for CUs and selected predictors (eg, luminance blocks predicting Cb- blocks and predictor Cr blocks) for the PU CU, residual blocks (eg, luminance residual blocks, Cb residual blocks, and Cr residual blocks) for the CU. For example, residual generator 102 may generate residual CUs such that each sample in the residual blocks has a value equal to the difference between a sample in the coding block of the CU and a corresponding sample in the corresponding selected predictive block of the CU PU.

[0239] Transform processing unit 104 may perform quadtree segmentation in order to segment residual blocks associated with a CU into transform blocks associated with a TU of the CU. Thus, a TU may be associated with a luma transform unit and two chrominance transform units. The sizes and positions of the CU TU luminance and chrominance transform blocks may or may not be based on the sizes and positions of the CU PU prediction blocks. A quadtree structure known as a "residual quadtree (RQT)" may include nodes associated with each of the regions. CU TUs may correspond to RQT leaf nodes. In other examples, transform processing module 104 may be configured to segment the TU in accordance with the segmentation techniques described herein. For example, video encoder 22 may not further divide CUs into TUs using an RQT structure. In this regard, in one example, a CU includes one TU.

[0240] Transform processing unit 104 may generate transform coefficient blocks for each CU TU by applying one or more transforms to the TU transform blocks. Transform processing module 104 may apply various transforms to a transform block associated with a TU. For example, transform processing module 104 may apply a discrete cosine transform (DCT), directional transform, or a conceptually similar transform to the transform block. In some examples, the transform processing module 104 does not apply transforms to the transform block. In such examples, a transform block may be treated as a transform coefficient block.

[0241] Quantization module 106 may quantize the transform coefficients in the coefficient block. The quantization process may reduce the bit depth associated with some or all of the transform coefficients. For example, an n-bit coefficient may be rounded down to an m-bit coefficient during quantization, where n is greater than m. Quantization unit 106 may quantize the coefficient block associated with the TU of the CU based on the value of a quantization parameter (QP) associated with the CU. Video encoder 22 may adjust the amount of quantization applied to the coefficient blocks associated with the CU by adjusting the QP value associated with the CU. Thus, the quantized transform coefficients may be less accurate than the original transform coefficients.

[0242] The inverse quantization unit 108 and the inverse transform processing unit 110 may apply inverse quantization and inverse transforms to the coefficient block, respectively, in order to recover the residual block from the coefficient block. Recovery module 112 may sum the recovered residual block with corresponding samples from one or more prediction blocks generated by prediction processing module 100 to generate a recovered transform block associated with the TU. By recovering the transform blocks for each TU CU in this way, video encoder 22 can recover the coding blocks of the CU.

[0243] Filtering module 114 may perform one or more deblocking operations to reduce blocking artifacts in coding blocks associated with a CU. The decoded movie frame buffer 116 may store the recovered coding blocks after the filter module 114 performs one or more deblocking operations on the recovered coding blocks. The inter prediction processing unit 120 may use the reference movie frame, which contains the recovered coding blocks, to perform inter prediction for PUs of other movie frames. In addition, the intra prediction processing unit 126 may use the recovered coding blocks in the decoded movie frame buffer 116 to perform intra prediction for other PUs in the same movie frame as the CU's movie frame.

[0244] Entropy encoding unit 118 may receive data from other functional components of video encoder 22. For example, entropy encoding unit 118 may receive blocks of coefficients from quantization unit 106 and may receive syntax elements from prediction processing unit 100. Entropy encoding module 118 may perform one or more entropy encoding operations on the data to generate entropy encoded data. For example, entropy encoding unit 118 may perform a CABAC operation, a context adaptive variable length coding (CAVLC) operation, a variable length variable (V2V) coding operation, a syntactic context adaptive binary arithmetic coding (SBAC) operation, an entropy coding operation based on segmentation into probability intervals (PIPE), an exponential Golomb encoding operation, or another type of entropy encoding operation for the data. Video encoder 22 may output a bit stream that includes entropy encoded data generated by entropy encoding module 118 . For example, the bitstream may include data that represents a segmentation structure for a CU according to the techniques of this disclosure.

[0245] FIG. 12 is a block diagram illustrating an exemplary video decoder 30 that is configured to implement the technologies of this disclosure. Fig. 12 is provided for purposes of explanation and is not a limitation of the technologies as illustrated and outlined in this disclosure. For purposes of explanation, this disclosure describes video decoder 30 in the context of HEVC coding. However, the techniques of this disclosure may be applicable to other standards or encoding methods.

[0246] In the example of FIG. 12, the video decoder 30 includes an entropy decoding unit 150, a video memory 151, a prediction processing unit 152, an inverse quantization unit 154, an inverse transform processing unit 156, a reconstruction unit 158, a filter unit 160, and a decoded movie frame buffer 162. The prediction processing unit 152 includes a motion compensation unit 164 and an intra prediction processing unit 166 . In other examples, video decoder 30 may include more, less, or other functional components.

[0247] The video data storage device 151 may store encoded video data, such as an encoded video bit stream, to be decoded by the components of the video decoder 30. The video data stored in the video data storage device 151 may be obtained, for example, from a computer-readable medium 16, for example, from a local video source , such as a camera, through the transmission of video data over a wired or wireless network, or through access to physical storage media. The video memory 151 may generate a coded picture buffer (CPB) that stores coded video data from the coded video bit stream. The decoded movie frame buffer 162 may be a reference movie frame memory that stores reference video data for use in decoding video data by video decoder 30, such as in intra- or inter-coding modes or for output. The video data memory 151 and the decoded movie frame buffer 162 may be formed by any of a plurality of memories, such as dynamic random access memory (DRAM) including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM) or other types of storage devices. Video storage 151 and decoded movie frame buffer 162 may be provided by identical storage or separate storage devices. In various examples, video data storage 151 may be on-chip with other components of video decoder 30 or off-chip with respect to these components. The video storage device 151 may be identical to, or be part of, the data storage media 28 of FIG. one.

[0248] The video data storage 151 receives and stores encoded video data (eg, NAL units) of the bitstream. The entropy decoding module 150 may receive encoded video data (eg, NAL units) from the video storage device 151 and may parse the NAL units to obtain syntax elements. Entropy decoding module 150 may entropy decode entropy encoded syntax elements in NAL units. Prediction processing unit 152, inverse quantization unit 154, inverse transform processing unit 156, reconstruction unit 158, and filter unit 160 may generate decoded video data based on syntax elements extracted from the bit stream. Module 150 entropy decoding, in General, can perform a process that is mutually inverse with respect to the process of module 118 entropy encoding.

[0249] In accordance with some examples of this disclosure, entropy decoding module 150 or another processing module of video decoder 30 may determine a tree structure as part of deriving syntax elements from a bitstream. The tree structure may indicate how an initial video block, such as a CTB, is segmented into smaller video blocks, such as coding units. In accordance with one or more technologies of this disclosure, for each respective non-leaf node of the tree structure, at each depth level of the tree structure, a plurality of allowed segmentation types are provided for the corresponding non-leaf node, and the video block corresponding to the corresponding non-leaf node is segmented into video blocks, corresponding to the child nodes of the corresponding non-leaf node, according to one of the set of valid partition patterns.

[0250] In addition to obtaining syntax elements from the bitstream, video decoder 30 may perform a recovery operation on a non-segmented CU. In order to perform a restore operation for a CU, video decoder 30 may perform a restore operation for each TU of the CU. By performing a restore operation for each CU TU, video decoder 30 can restore the residual CUs. As explained above, in one example of an entity disclosure, a CU includes one TU.

[0251] As part of performing a recovery operation on the TU CU, inverse quantizer 154 may inverse quantize, i.e. dequantize, blocks of coefficients associated with the TU. After inverse quantization module 154 inversely quantizes the coefficient block, inverse transform processing module 156 may apply one or more inverse transforms to the coefficient block to generate a residual block associated with the TU. For example, inverse transform processing module 156 may apply an inverse DCT, inverse integer transform, inverse Karhunen-Loeve (KLT), inverse rotational, inverse directional transform, or other inverse transform to the coefficient block.

[0252] If the PU CU is encoded using intra prediction, the intra prediction processing unit 166 may perform intra prediction in order to generate PU predictors. Intra prediction processing unit 166 may use an intra prediction mode to generate predictive PUs based on spatially adjacent sample blocks. The intra prediction processing unit 166 may determine the intra prediction mode for the PU based on one or more syntax elements obtained from the bit stream.

[0253] In one example, the intra prediction processing module 166 may be configured to implement entity disclosure technologies. In other examples, other blocks or modules may be configured to implement all or some of the entity disclosure technologies.

[0254] In addition, if the PU is encoded using inter prediction, entropy decoding unit 150 may determine motion information for the PU. Motion compensation module 164 may determine, based on the motion information of the PU, one or more reference blocks. Motion compensation module 164 may generate, based on one or more reference blocks, predictive blocks (eg, luminance predictor blocks, Cb predictor blocks, and Cr predictor blocks) for the PU. As explained above, a CU may include only one PU. Thus, a CU may not be split into multiple PUs.

[0255] Recovery module 158 may use transform blocks (eg, luma transform blocks, Cb transform blocks, and Cr transform blocks) for CU TUs and predictive blocks (eg, luma blocks, Cb blocks, and Cr blocks) of PUs. CU, i.e. either intra prediction data or inter prediction data, under appropriate conditions, in order to recover coding blocks (eg, luminance coding blocks, Cb coding blocks, and Cr coding blocks) for the CU. For example, reconstruction module 158 may add samples of transform blocks (e.g., luminance transform blocks, Cb transform blocks, and Cr transform blocks) with corresponding samples of predictors (e.g., luma predictors, Cb predictors, and Cr predictors). ) in order to recover coding blocks (eg, luminance coding blocks, Cb coding blocks, and Cr coding blocks) of the CU.

[0256] Filtering module 159 may perform a deblocking operation in order to reduce blocking artifacts associated with coding units of the CU. Video decoder 30 may store CUs in decoded movie frame buffer 162 . The decoded movie frame buffer 162 may provide reference frames for subsequent motion compensation, intra prediction, and presentation on a display device, such as display device 32 of FIG. 1. For example, video decoder 30 may perform, based on blocks in decoded movie frame buffer 162, intra-prediction or inter-prediction operations for PUs of other CUs.

[0257] The video decoder outputs a decoded version of the current movie frame, which includes the decoded version of the current block. When the video decoder is a video decoder capable of outputting displayed decoded video, the video decoder may, for example, output a decoded version of the current movie frame to a display device. When decoding is performed as part of a decoding loop of a video encoding process, the video decoder may store a decoded version of the current movie frame as a reference movie frame for use in encoding another movie frame of video data.

[0258] Specific aspects of this disclosure are described with respect to extensions to the HEVC standard for purposes of illustration. However, the techniques described in this disclosure may be useful for other video encoding processes, including other standard or proprietary video encoding processes not yet developed.

[0259] A video encoder, as described in this disclosure, may mean a video encoder or a video decoder. Likewise, a video encoding module may mean a video encoder or a video decoder. Likewise, video encoding may mean video encoding or video decoding, as appropriate. In this disclosure, the phrase "based" may indicate based only, at least partially based, or based in some way. This disclosure may use the term "video unit" or "video block" or "block" to mean one or more sample blocks and syntax structures used to encode samples of one or more sample blocks. Exemplary types of video units may include CTUs, CUs, PUs, transform units (TUs), macroblocks, macroblock segments, and so on. In some contexts, the PU explanation may be replaced by a macroblock or macroblock segment explanation. Exemplary video block types may include coding tree blocks, coding blocks, and other types of video data blocks.

[0260] The technologies of this disclosure are not necessarily limited to wireless communication applications or settings. The technologies may be applied to video coding in support of any of a variety of multimedia applications such as over-the-air television broadcasts, cable television, satellite television, Internet video streaming such as dynamic adaptive streaming over HTTP (DASH), digital video that is encoded onto a storage medium, decoding digital video stored on a storage medium, or other applications. In some examples, the system may be configured to support one-way or two-way video in order to support applications such as video streaming, video playback, video broadcast, and/or video telephony.

[0261] As used herein, the term "computer-readable medium" includes, but is not limited to, portable or non-portable storage devices, optical storage devices, and various other media capable of storing, containing, or carrying instruction(s) and/ or data. The computer-readable medium may include a non-volatile medium on which data can be stored and which does not include carrier waves and/or transient electronic signals propagated wirelessly or over wired connections. Examples of non-volatile media may include, but are not limited to, a magnetic disk or tape, optical storage media such as a compact disc (CD) or digital versatile disc (DVD), flash memory, a storage device or storage devices. The computer-readable medium may have stored code and/or computer-executable instructions that may represent a procedure, function, subroutine, program, procedure, nested procedure, module, software package, class, or any combination of instructions, data structures, or program statements. A code segment may be associated with another code segment or hardware circuitry by sending and/or receiving information, data, arguments, parameters, or storage device content. Information, arguments, options, data, etc. may be forwarded, redirected, or transmitted by any appropriate means, including storage sharing, message forwarding, token forwarding, network transmission, and so on.

[0262] In some embodiments, computer-readable storage devices, media, and storage devices may include a cable or wireless signal containing a bit stream, and the like. However, if mentioned, non-volatile computer-readable storage media explicitly excludes media such as energy, carrier signals, electromagnetic waves, and signals per se.

[0263] Specific details are provided in the above description in order to provide a thorough understanding of the embodiments and examples provided herein. However, those skilled in the art will appreciate that the embodiments may be practiced without these specific details. For clarity of explanation, in some cases, the present technology may be represented as including separate functional blocks, including functional blocks containing devices, device components, steps or procedures in a method implemented in software or in combinations of hardware and software. Additional components other than those shown in the drawings and/or described herein may be used. For example, circuits, systems, networks, processes, and other components may be shown as components in block diagram form so as not to obscure the embodiments in unnecessary detail. In other instances, commonly used schemes, processes, algorithms, structures, and techniques may be shown without unnecessary detail so as not to obscure the embodiments.

[0264] Individual embodiments may be described above as a process or method, which is illustrated as a flowchart, flow diagram, data flow diagram, block diagram, or block diagram. While the flowchart may describe the operations as a sequential process, many of the operations may be performed in parallel or simultaneously. In addition, the order of operations can be rearranged. The process ends when the operations are completed, but may have additional steps not included in the drawing. A process may correspond to a method, a function, a procedure, a subroutine, a subroutine, and so on. When a process matches a function, its termination corresponds to the return of the function to the calling function or main function.

[0265] The processes and methods of the examples described above may be implemented using computer-executable instructions that are stored on or otherwise accessible from computer-readable media. Such instructions may include, for example, instructions and data that instruct or otherwise configure a general purpose computer, special purpose computer, or processing device to perform a specific function or group of functions. Portions of the computer resources used may be available over the network. Machine-executable instructions, for example, may be binary files, instructions in an intermediate format such as assembly language, firmware, source code, and so on. Examples of computer-readable media that can be used to store instructions, information used, and/or information created during the methods of the examples described include magnetic or optical disks, flash memory, USB devices containing non-volatile storage device, network storage devices, etc.

[0266] The device implementation processes and methods according to these disclosures may include hardware, software, firmware, middleware, microcode, hardware description languages, or any combination of the foregoing, and may take any of a variety of form factors. When implemented in software, firmware, middleware, or microcode, program code or code segments to perform necessary tasks (eg, a computer program product) may be stored on a computer-readable or computer-readable medium. The processors can perform the required tasks. Typical examples of form factors include laptops, smartphones, mobile phones, tablet devices or other miniature form factor personal computers, personal digital devices, rack-mounted devices, stand-alone devices, and so on. The functionality described in this document may also be implemented in peripheral devices or expansion cards. Such functionality can also be implemented on a circuit board for different chips or different processes running in the same device, as a further example.

[0267] Instructions, media for transmitting such instructions, computing resources for executing them, and other structures for supporting such computing resources are exemplary means for providing the functions described in the disclosure.

[0268] In the above description, aspects of the application are described with reference to specific embodiments thereof, but those skilled in the art should recognize that the application is not limited thereto. Thus, while illustrative embodiments of the application are described in detail herein, it should be understood that the teachings of the invention may be carried out and used in other and different ways, and that the appended claims are intended to be construed as including such variations, except as limited through the prior art. Various features and aspects of the above application may be used separately or combined. Additionally, the embodiments may be used in any number of environments and applications, in addition to the environments and applications described herein, without departing from the broader spirit and scope of the detailed description. Accordingly, the detailed description and drawings are to be considered illustrative and not restrictive. For purposes of illustration, the methods are described in specific order. It should be appreciated that in alternative embodiments, the methods may be performed in an order other than the order described.

[0269] Those skilled in the art will appreciate that the less than ("<") and greater than (">") symbols or terminology used herein may be replaced by less than or equal ("≤") and greater than or equals ("≥"), respectively, without departing from the scope of this description.

[0270] If components are described as "capable" of performing certain operations, such configuration may be achieved, for example, by designing electronic circuits or other hardware with the ability to perform an operation, by programming programmable electronic circuits (e.g., microprocessors or other suitable electronic circuits ) with the ability to perform the operation or through any combination of the above.

[0271] The phrase "connected to" means any component that is physically connected to another component, directly or indirectly, and/or any component that communicates with another component (e.g., connects to another component via a wired or wireless connection and/or other appropriate communication interface) directly or indirectly.

[0272] The text of the claims or other text setting out "at least one of" the set indicates that one element of the set or several elements of the set satisfy the requirement. For example, the text of the claims stating "at least one of A and B" means A, B or A and B.

[0273] The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computing software, or combinations of the foregoing. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of functionality. Whether this functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in a variety of ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of this application.

[0274] The technologies described herein may also be implemented in electronic hardware, computer software, firmware, or any combination of the foregoing. Such technologies may be implemented in any of a variety of devices, such as general purpose computers, wireless handsets, or integrated circuit devices, having multiple uses, including the use in wireless handsets, as well as other devices. . Any features described as modules or components may be implemented together in an integrated logic device or separately as discrete but interoperable logic devices. When implemented in software, the techniques may be implemented at least in part by a computer-readable storage medium containing program code including instructions that, when executed, perform one or more of the methods described above. The computer-readable medium may form part of a computer program product, which may include packaging. The computer readable storage medium may comprise memory devices or storage media such as random access memory (RAM), such as synchronous dynamic random access memory (SDRAM), read only memory (ROM), nonvolatile random access memory (NVRAM), electrically erasable programmable read only memory (EEPROM), flash memory, magnetic or optical storage media, and the like. Additionally or alternatively, the techniques may be implemented at least in part by a computer-readable communication medium that carries or transmits program code in the form of instructions or data structures and that can be accessed, read and/or executed by a computer, such as distributed signals or waves.

[0275] Software code is executed by a processor that includes one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or others. equivalent integrated or discrete logic circuits. Such a processor may be configured to implement any of the technologies described in this disclosure. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors together with a DSP core, or any other such configuration. Accordingly, the term "processor" as used herein can mean any of the above structures, any combination of the above structures, or any other structure or hardware suitable for implementing the technologies described herein. In addition, in some aspects, the functionality described herein may be provided within specialized software modules or hardware modules capable of encoding or decoding, or embedded in a combined video encoder/decoder (codec).

Claims (215)

1. A method for decoding video data, the method comprising the steps of: - determine the size of the current block of video data; determining, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using an angle of the wide-angle intra prediction mode; one or more position-dependent intra prediction combining (PDPC) reference samples that are external to the current block are determined to modify a plurality of intra predictive prediction samples of the prediction block, each PDPC reference sample from one or more reference PDPCs -samples is determined using the angle of the wide-angle intra prediction mode with respect to the corresponding intra predictive prediction sample from the plurality of intra predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; and - restore the block based on the modified predictive sample and the residual value. 2. The method of claim 1, wherein determining the size of the current box includes determining that the width of the current box and the height of the current box are different sizes. 3. The method of claim 1, wherein the intra wide-angle mode angle is less than -135 degrees or greater than 45 degrees with respect to the intra-predicted prediction sample. 4. The method according to claim 1, further comprising the step of: - determining one or more weight coefficients based on the X and Y coordinates of the internally predicted predictive sample, wherein the modification of the internally predicted predictive sample comprises the step of modifying the internally predicted predictive sample in order to generate a modified predictive sample based on the determined one or more reference PDPC samples, one or more weights determined, and an internally predicted predictive sample. 5. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block comprises determining one or more PDPC reference samples having both an X coordinate and a Y coordinate that differ from the respective X coordinate and Y coordinate of the internally predicted prediction sample in the prediction block. 6. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block comprises: - determine the line that is above the current block; - determining the X coordinate in the determined row, wherein the X coordinate in the determined row is equal to the X coordinate of the internally predicted predictive sample plus the Y coordinate of the internally predicted predictive sample plus 1; and - determine a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 7. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block comprises: - define the column that is located to the left of the current block; - determine the Y coordinate in a certain column, while the Y coordinate in a certain column is equal to the Y coordinate of the internally predicted predictive sample plus the X coordinate of the internally predicted predictive sample plus 1; and - determining a reference PDPC sample from one or more reference PDPC samples based on a certain column and a certain Y-coordinate. 8. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block comprises: - determine the line that is above the current block; determining an X coordinate in the determined row, wherein the X coordinate in the determined row is based on an angle of the wide-angle intra-prediction mode with respect to the intra-predictive prediction sample; and - determine a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 9. The method according to claim 8, in which determining the X coordinate in a certain line comprises the steps of: - determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining an X coordinate in a certain row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 10. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block comprises: - define the column that is located to the left of the current block; determining a Y coordinate in a certain column, wherein the Y coordinate in a certain column is based on an angle of a wide-angle intra prediction mode; and - determining a reference PDPC sample from one or more reference PDPC samples based on a certain column and a certain Y-coordinate. 11. The method of claim 10, wherein determining the Y coordinate in a specific column comprises the steps of: - determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining a Y coordinate in a certain column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 12. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: determining a set of one or more samples based on the wide-angle intra prediction mode; and performing at least one of interpolation, rounding with offset, or rounding without offset of the set of one or more samples in order to generate one or more PDPC reference samples. 13. The method of claim 1, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode are not stored in the linear reference buffer; and one or more PDPC reference samples are determined based on the last PDPC reference sample stored in the linear reference buffer. 14. The method of claim 1, wherein modifying the first intra predictive block prediction sample of a plurality of intra predictive prediction samples of the prediction block comprises modifying the first intra predictive block prediction sample, wherein the one or more reference PDPC samples comprise a first set from one or more PDPC reference samples, the method further comprising: determining, for the second intra predictive prediction sample of the prediction block, that at least one PDPC reference sample from a second set of one or more PDPC reference samples for the second intra predictive predictive sample is not stored in the linear reference buffer; and one of not applying the PDPC to the second internally predicted predictive sample or applying the PDPC using only the PDPC reference samples available in the linear reference buffer is performed. 15. The method of claim 1, wherein the wide-angle intra prediction mode is not a DC-, planar, horizontal, or vertical intra prediction mode. 16. A method for encoding video data, the method comprising the steps of: - determine the size of the current block of video data; determining, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using an angle of the wide-angle intra prediction mode; determining one or more reference samples using position-dependent intra-prediction combining (PDPC) that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, wherein each reference PDPC sample of one or more reference PDPCs is the samples are determined using the angle of the wide-angle intra prediction mode with respect to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; - determine the residual value for the residual block based on the modified predictive sample and the value of the sample in the current block; and - transmit in service signals information indicating the residual value. 17. The method of claim 16, wherein determining the size of the current box includes determining that the width of the current box and the height of the current box are different sizes. 18. The method of claim 16, wherein the wide-angle intra prediction mode angle is less than -135 degrees or greater than 45 degrees with respect to the intra-predicted prediction sample. 19. The method of claim 16, further comprising the step of: - determining one or more weight coefficients based on the X and Y coordinates of the internally predicted predictive sample, wherein the modification of the internally predicted predictive sample comprises the step of modifying the internally predicted predictive sample in order to generate a modified predictive sample based on the determined one or more reference PDPC samples, one or more weights determined, and an internally predicted predictive sample. 20. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block comprises determining one or more PDPC reference samples having both an X coordinate and a Y coordinate that differ from the respective X coordinate and Y coordinate of the internally predicted prediction sample in the prediction block. 21. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block comprises: - determine the line that is above the current block; - determining the X coordinate in the determined row, wherein the X coordinate in the determined row is equal to the X coordinate of the internally predicted predictive sample plus the Y coordinate of the internally predicted predictive sample plus 1; and - determine a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 22. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block comprises: - define the column that is located to the left of the current block; - determine the Y coordinate in a certain column, while the Y coordinate in a certain column is equal to the Y coordinate of the internally predicted predictive sample plus the X coordinate of the internally predicted predictive sample plus 1; and - determining a reference PDPC sample from one or more reference PDPC samples based on a certain column and a certain Y-coordinate. 23. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block comprises: - determine the line that is above the current block; determining an X coordinate in the determined row, wherein the X coordinate in the determined row is based on an angle of the wide-angle intra-prediction mode with respect to the intra-predictive prediction sample; and - determine a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 24. The method according to claim 23, wherein determining the X coordinate in a particular row comprises the steps of: - determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining an X coordinate in a certain row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 25. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block comprises: - define the column that is located to the left of the current block; determining a Y coordinate in a certain column, wherein the Y coordinate in a certain column is based on an angle of a wide-angle intra prediction mode; and - determining a reference PDPC sample from one or more reference PDPC samples based on a certain column and a certain Y-coordinate. 26. The method of claim 25, wherein determining the Y coordinate in a specific column comprises the steps of: - determining one of the cotangent or tangent of the angle of the wide-angle intra prediction mode; and determining a Y coordinate in a certain column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 27. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: determining a set of one or more samples based on the wide-angle intra prediction mode; and performing at least one of interpolation, rounding with offset, or rounding without offset of the set of one or more samples in order to generate one or more PDPC reference samples. 28. The method of claim 16, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode are not stored in the linear reference buffer; and one or more PDPC reference samples are determined based on the last PDPC reference sample stored in the linear reference buffer. 29. The method of claim 16, wherein modifying a first prediction block intra predictive sample of a plurality of intra predictive prediction samples of the prediction block comprises modifying the first intra predictive prediction sample of the prediction block, wherein the one or more reference PDPC samples comprise a first set from one or more PDPC reference samples, the method further comprising: determining, for the second intra predictive prediction sample of the prediction block, that at least one PDPC reference sample from a second set of one or more PDPC reference samples for the second intra predictive predictive sample is not stored in the linear reference buffer; and one of not applying the PDPC to the second internally predicted predictive sample or applying the PDPC using only the PDPC reference samples available in the linear reference buffer is performed. 30. The method of claim 16, wherein the wide-angle intra prediction mode is not a DC-, planar, horizontal, or vertical intra prediction mode. 31. Device for decoding video data, wherein the device contains: a storage device configured to store one or more prediction blocks; and - a video decoder comprising at least one of a fixed functional or programmable circuit, wherein the video decoder is configured to: - determine the size of the current block of video data; - determine, based on the size of the current block, the wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using the wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using the angle of the wide-angle intra prediction mode; determine one or more reference samples using position-dependent intra-prediction combining (PDPC) that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, where each reference PDPC sample of one or more reference PDPCs is the samples are determined using the angle of the wide-angle intra prediction mode with respect to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; and - restore the block based on the modified predictive sample and the residual value. 32. The apparatus of claim 31, wherein determining the size of the current block includes determining that the width of the current block and the height of the current block are different sizes. 33. The apparatus of claim 31, wherein the intra-prediction wide-angle mode angle is less than -135 degrees or greater than 45 degrees with respect to the intra-predicted prediction sample. 34. The apparatus of claim 31, wherein the video decoder is configured to: - determine one or more weights based on the X and Y coordinates of the internally predicted predictive sample, wherein the modification of the internally predicted predictive sample comprises modifying the internally predicted predictive sample in order to generate a modified predictive sample based on the determined one or more PDPC reference samples, the determined one or more weights; and the internally predicted prediction sample. 35. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block comprises defining one or more PDPC reference samples having both an X coordinate and a Y coordinate that differ from the corresponding X coordinate. and the Y coordinates of the internally predicted prediction sample in the prediction block. 36. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the line that is above the current block; - determining the x-coordinate in the specific row, wherein the x-coordinate in the specific row is equal to the x-coordinate of the internally predicted predictive sample plus the y-coordinate of the internally predicted predictive sample plus 1; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 37. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the column that is located to the left of the current block; - determining a Y-coordinate in a certain column, wherein the Y-coordinate in a certain column is equal to the Y-coordinate of the internally predicted predictive sample plus the X-coordinate of the internally predicted predictive sample plus 1; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific column and a specific Y coordinate. 38. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the line that is above the current block; - determining an X coordinate in a certain line, wherein the X coordinate in a certain line is based on the angle of the wide-angle intra-prediction mode relative to the internal-predicted prediction sample; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 39. The device according to claim 38, in which the definition of the X coordinate in a certain line contains: - determining one of the cotangent or tangent of the angle of the wide-angle indoor prediction mode; and - determining an X coordinate in a certain row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 40. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the column that is located to the left of the current block; - determining a Y coordinate in a certain column, wherein the Y coordinate in a certain column is based on the angle of the wide-angle intra prediction mode; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific column and a specific Y coordinate. 41. The device according to claim 40, in which the definition of the Y coordinate in a certain column contains: - determining one of the cotangent or tangent of the angle of the wide-angle indoor prediction mode; and - determining the Y coordinate in a specific column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the x-coordinate of the intra-predictive prediction sample, and the Y-coordinate of the intra-predictive prediction sample. 42. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining a set of one or more samples based on the wide-angle intra prediction mode; and at least one of interpolation, rounding with offset, or rounding without offset of a set of one or more samples in order to generate one or more PDPC reference samples. 43. The apparatus of claim 31, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode are not stored in the linear reference buffer; and - determining one or more PDPC reference samples based on the last PDPC reference sample stored in the linear reference buffer. 44. The apparatus of claim 31, wherein modifying the intra predictive prediction sample of a plurality of intra predictive prediction samples of the prediction block comprises modifying the first intra predictive prediction sample of the prediction block, wherein the one or more reference PDPC samples comprise a first set of one or more reference PDPC samples, and the video decoder is configured to: - determine, for the second intra predictive prediction sample of the prediction block, that at least one PDPC reference sample from the second set of one or more PDPC reference samples for the second intra predictive predictive sample is not stored in the linear reference buffer; and - perform one of not applying the PDPC to the second internally predicted predictive sample, or applying the PDPC only using the PDPC reference samples available in the linear reference buffer. 45. The apparatus of claim 31, wherein the wide-angle intra prediction mode is not a DC-, planar, horizontal, or vertical intra prediction mode. 46. The apparatus of claim 31, further comprising a display configured to display the current block. 47. The apparatus of claim 31, wherein the apparatus comprises one or more of a camera, a computer, a mobile device, a broadcast receiver, or a set-top box. 48. Device for encoding video data, wherein the device contains: a storage device configured to store one or more prediction blocks; and - a video encoder comprising at least one of a fixed functional or programmable circuit, wherein the video encoder is configured to: - determine the size of the current block of video data; - determine, based on the size of the current block, the wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using the wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using the angle of the wide-angle intra prediction mode; determine one or more reference samples using position-dependent intra-prediction combining (PDPC) that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, where each reference PDPC sample of one or more reference PDPCs is the samples are determined using the angle of the wide-angle intra prediction mode with respect to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; and - determine the residual value for the residual block based on the modified predictive sample and the sample value in the current block; and - transmit information indicating the residual value in service signals. 49. The apparatus of claim 48, wherein determining the size of the current block includes determining that the width of the current block and the height of the current block are different sizes. 50. The apparatus of claim 48, wherein the intra-prediction wide-angle mode angle is less than -135 degrees or greater than 45 degrees with respect to the intra-predicted prediction sample. 51. The apparatus of claim 48, wherein the video encoder is configured to: - determine one or more weights based on the X and Y coordinates of the internally predicted predictive sample, wherein the modification of the internally predicted predictive sample comprises modifying the internally predicted predictive sample in order to generate a modified predictive sample based on the determined one or more reference PDPC samples, the determined one or more weights; and the internally predicted prediction sample. 52. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block comprises defining one or more PDPC reference samples having both an X coordinate and a Y coordinate that differ from the corresponding X coordinate. and the Y coordinates of the internally predicted prediction sample in the prediction block. 53. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the line that is above the current block; - determining the x-coordinate in the specific row, wherein the x-coordinate in the specific row is equal to the x-coordinate of the internally predicted predictive sample plus the y-coordinate of the internally predicted predictive sample plus 1; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 54. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the column that is located to the left of the current block; - determining a Y-coordinate in a certain column, wherein the Y-coordinate in a certain column is equal to the Y-coordinate of the internally predicted predictive sample plus the X-coordinate of the internally predicted predictive sample plus 1; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific column and a specific Y coordinate. 55. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the line that is above the current block; - determining an X coordinate in a certain line, wherein the X coordinate in a certain line is based on the angle of the wide-angle intra-prediction mode relative to the internal-predicted prediction sample; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific row and a specific x-coordinate. 56. The device according to claim 55, in which the definition of the X coordinate in a certain line contains: - determining one of the cotangent or tangent of the angle of the wide-angle indoor prediction mode; and - determining an X coordinate in a certain row based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the X coordinate of the intra predictive sample, and the Y coordinate of the intra predictive sample. 57. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block comprises: - definition of the column that is located to the left of the current block; - determining a Y coordinate in a certain column, wherein the Y coordinate in a certain column is based on the angle of the wide-angle intra prediction mode; and - determining a PDPC reference sample from one or more PDPC reference samples based on a specific column and a specific Y coordinate. 58. The device according to claim 57, in which the definition of the Y coordinate in a certain column contains: - determining one of the cotangent or tangent of the angle of the wide-angle indoor prediction mode; and - determining the Y coordinate in a specific column based on one of the cotangent or tangent of the angle of the wide-angle intra prediction mode, the x-coordinate of the intra-predictive prediction sample, and the Y-coordinate of the intra-predictive prediction sample. 59. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining a set of one or more samples based on the wide-angle intra prediction mode; and at least one of interpolation, rounding with offset, or rounding without offset of a set of one or more samples in order to generate one or more PDPC reference samples. 60. The apparatus of claim 48, wherein determining one or more PDPC reference samples that are external to the current block based on the wide-angle intra prediction mode comprises: - determining that one or more samples external to the current block identified based on the wide-angle intra prediction mode are not stored in the linear reference buffer; and - determining one or more PDPC reference samples based on the last PDPC reference sample stored in the linear reference buffer. 61. The apparatus of claim 48, wherein modifying the intra predictive prediction sample of a plurality of intra predictive prediction samples of the prediction block comprises modifying the first intra predictive prediction sample of the prediction block, wherein the one or more reference PDPC samples comprise a first set of one or more reference PDPC samples, and the video encoder is configured to: - determine, for the second intra predictive prediction sample of the prediction block, that at least one PDPC reference sample from the second set of one or more PDPC reference samples for the second intra predictive predictive sample is not stored in the linear reference buffer; and - perform one of not applying the PDPC to the second internally predicted predictive sample, or applying the PDPC only using the PDPC reference samples available in the linear reference buffer. 62. The apparatus of claim 48, wherein the wide-angle intra prediction mode is not a DC-, planar, horizontal, or vertical intra prediction mode. 63. The apparatus of claim 48, wherein the apparatus comprises one or more of a camera, a computer, a mobile device, a broadcast receiver, or a set-top box. 64. A computer-readable storage medium that stores instructions that, when executed, instruct one or more device processors to decode video data: - determine the size of the current block of video data; - determine, based on the size of the current block, the wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using the wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using the angle of the wide-angle intra prediction mode; - determine one or more reference samples using position-dependent intra-prediction combining (PDPC) that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, with each reference PDPC sample from one or more reference PDPCs -samples is determined using the angle of the wide-angle intra-prediction mode relative to the corresponding intra-predictive prediction sample from the plurality of intra-predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; and - restore the current block based on the modified predictive sample and the residual value. 65. A computer-readable storage medium that stores instructions that, when executed, instruct one or more processors of a device for encoding video data: - determine the size of the current block of video data; - determine, based on the size of the current block, the wide-angle intra prediction mode to be used for the current block; determining a prediction block for the current block using the wide-angle intra prediction mode, the prediction block including a plurality of intra-predictive prediction samples determined using the angle of the wide-angle intra prediction mode; determine one or more reference samples using position-dependent intra-prediction combining (PDPC) that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, where each reference PDPC sample of one or more reference PDPCs is the samples are determined using the angle of the wide-angle intra prediction mode with respect to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; modifying, using one or more PDPC reference samples, an intra predictive sample from a plurality of predictor block intra predictive samples to generate a modified predictive sample; - determine the residual value for the residual block based on the modified predictive sample and the sample value in the current block; and - transmit information indicating the residual value in service signals. 66. Device for decoding video data, wherein the device contains: means for determining the size of the current block of video data; means for determining, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; means for determining a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of intra-predicted prediction samples determined using an angle of the wide-angle intra prediction mode; means for determining one or more position-dependent intra-prediction combining (PDPC) reference samples that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, each PDPC reference sample of one or more the PDPC reference samples are determined using the angle of the wide-angle intra prediction mode relative to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; means for modifying, using one or more PDPC reference samples, an internally predicted prediction sample from a plurality of internally predicted predictive samples of the predictor block in order to generate a modified prediction sample; and means for restoring the current block based on the modified predictive sample and the residual. 67. Device for encoding video data, wherein the device contains: means for determining the size of the current block of video data; means for determining, based on the size of the current block, a wide-angle intra prediction mode to be used for the current block; means for determining a prediction block for the current block using a wide-angle intra prediction mode, the prediction block including a plurality of intra-predicted prediction samples determined using an angle of the wide-angle intra prediction mode; means for determining one or more position-dependent intra-prediction combining (PDPC) reference samples that are external to the current block to modify a plurality of intra-predictive prediction samples of the prediction block, each PDPC reference sample of one or more the PDPC reference samples are determined using the angle of the wide-angle intra prediction mode relative to the corresponding intra predictive prediction sample of the plurality of intra predictive prediction samples; means for modifying, using one or more PDPC reference samples, an internally predicted prediction sample from a plurality of internally predicted predictive samples of the predictor block in order to generate a modified prediction sample; means for determining a residual value for the residual block based on the modified predictive sample and the sample value in the current block; and means for signaling information indicating the residual value.

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