Patent Description:
Intra prediction modes used in High Efficiency Video Coding (HEVC) are illustrated in <FIG>. In HEVC, there is a total of <NUM> intra prediction modes, among which mode <NUM> (<NUM>) is a horizontal mode, mode <NUM> (<NUM>) is a vertical mode, and mode <NUM> (<NUM>), mode <NUM> (<NUM>) and mode <NUM> (<NUM>) are diagonal modes. The intra prediction modes are signaled by three most probable modes (MPMs) and <NUM> remaining modes.

To code an intra mode, a most probable mode (MPM) list of size <NUM> is built based on intra modes of the neighboring blocks. This MPM list will be referred to as the MPM list or a primary MPM list. One MPM flag is signaled to indicate whether a current mode belongs to the MPM list. If the MPM flag is true, an unary code is used to signal an MPM index. If the MPM flag is false, a <NUM> bit fix length coding is used to signal the remaining modes.

A process of generating the MPM list generation is shown as follows. Here, leftIntraDir indicates a mode in a left block, and aboveIntraDir indicates a mode in an above block. If the left or above block is currently not available, leftIntraDir or aboveIntraDir is set to an index DC_IDX. In addition, variables "offset " and "mod" are the constant values, which are set to <NUM> and <NUM>, respectively.

According to embodiments, a method of controlling intra prediction for decoding of a video sequence according to claim <NUM>, an apparatus for controlling intra prediction of a video sequence according to claim <NUM> and a non-transitory computer readable storage medium according to claim <NUM> are provided.

<FIG> is a simplified block diagram of a communication system (<NUM>) according to an embodiment. The communication system (<NUM>) may include at least two terminals (<NUM>-<NUM>) interconnected via a network (<NUM>). For unidirectional transmission of data, a first terminal (<NUM>) may code video data at a local location for transmission to the other terminal (<NUM>) via the network (<NUM>). The second terminal (<NUM>) may receive the coded video data of the other terminal from the network (<NUM>), decode the coded data and display the recovered video data.

<FIG> illustrates a second pair of terminals (<NUM>, <NUM>) provided to support bidirectional transmission of coded video that may occur, for example, during videoconferencing. For bidirectional transmission of data, each terminal (<NUM>, <NUM>) may code video data captured at a local location for transmission to the other terminal via the network (<NUM>). Each terminal (<NUM>, <NUM>) also may receive the coded video data transmitted by the other terminal, may decode the coded data and may display the recovered video data at a local display device.

In <FIG>, the terminals (<NUM>-<NUM>) may be illustrated as servers, personal computers and smart phones but the principles of embodiments are not so limited. Embodiments find application with laptop computers, tablet computers, media players and/or dedicated video conferencing equipment. The network (<NUM>) represents any number of networks that convey coded video data among the terminals (<NUM>-<NUM>), including for example wireline and/or wireless communication networks. For the purposes of the present discussion, the architecture and topology of the network (<NUM>) may be immaterial to the operation of embodiments unless explained herein below.

<FIG> is a diagram of a placement of a video encoder and a video decoder in a streaming environment, according to an embodiment.

A streaming system may include a capture subsystem (<NUM>) that can include a video source (<NUM>), for example a digital camera, creating, for example, an uncompressed video sample stream (<NUM>). That sample stream (<NUM>), depicted as a bold line to emphasize a high data volume when compared to encoded video bitstreams, can be processed by an encoder (<NUM>) coupled to the camera (<NUM>). The encoder (<NUM>) can include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter as described in more detail below. The encoded video bitstream (<NUM>), depicted as a thin line to emphasize the lower data volume when compared to the sample stream, can be stored on a streaming server (<NUM>) for future use. One or more streaming clients (<NUM>, <NUM>) can access the streaming server (<NUM>) to retrieve copies (<NUM>, <NUM>) of the encoded video bitstream (<NUM>). A client (<NUM>) can include a video decoder (<NUM>) which decodes the incoming copy of the encoded video bitstream (<NUM>) and creates an outgoing video sample stream (<NUM>) that can be rendered on a display (<NUM>) or other rendering device (not depicted). In some streaming systems, the video bitstreams (<NUM>, <NUM>, <NUM>) can be encoded according to certain video coding/compression standards. Examples of those standards include ITU-T Recommendation H. Under development is a video coding standard informally known as VVC. The disclosed subject matter may be used in the context of VVC.

<FIG> is a functional block diagram of a video decoder (<NUM>) according to an embodiment.

A receiver (<NUM>) may receive one or more codec video sequences to be decoded by the decoder (<NUM>); in the same or an embodiment, one coded video sequence at a time, where the decoding of each coded video sequence is independent from other coded video sequences. To combat network jitter, a buffer memory (<NUM>) may be coupled in between receiver (<NUM>) and entropy decoder / parser (<NUM>) ("parser" henceforth). When receiver (<NUM>) is receiving data from a store/forward device of sufficient bandwidth and controllability, or from an isosychronous network, the buffer (<NUM>) may not be needed, or can be small. For use on best effort packet networks such as the Internet, the buffer (<NUM>) may be required, can be comparatively large and can advantageously of adaptive size.

The video decoder (<NUM>) may include a parser (<NUM>) to reconstruct symbols (<NUM>) from the entropy coded video sequence. Categories of those symbols include information used to manage operation of the decoder (<NUM>), and potentially information to control a rendering device such as a display (<NUM>) that is not an integral part of the decoder but can be coupled to it, as was shown in <FIG>. The control information for the rendering device(s) may be in the form of Supplementary Enhancement Information (SEI messages) or Video Usability Information (VUI) parameter set fragments (not depicted). The parser (<NUM>) may parse / entropy-decode the coded video sequence received. The coding of the coded video sequence can be in accordance with a video coding technology or standard, and can follow principles well known to a person skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and so forth. The parser (<NUM>) may extract from the coded video sequence, a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder, based upon at least one parameters corresponding to the group. The entropy decoder / parser may also extract from the coded video sequence information such as transform coefficients, quantizer parameter (QP) values, motion vectors, and so forth.

The parser (<NUM>) may perform entropy decoding / parsing operation on the video sequence received from the buffer (<NUM>), so to create symbols (<NUM>). The parser (<NUM>) may receive encoded data, and selectively decode particular symbols (<NUM>). Further, the parser (<NUM>) may determine whether the particular symbols (<NUM>) are to be provided to a Motion Compensation Prediction unit (<NUM>), a scaler / inverse transform unit (<NUM>), an Intra Prediction unit (<NUM>), or a loop filter unit (<NUM>).

Beyond the functional blocks already mentioned, decoder (<NUM>) can be conceptually subdivided into a number of functional units as described below.

The scaler / inverse transform unit (<NUM>) receives quantized transform coefficient as well as control information, including which transform to use, block size, quantization factor, quantization scaling matrices, etc. as symbol(s) (<NUM>) from the parser (<NUM>). It can output blocks comprising sample values that can be input into aggregator (<NUM>).

In some cases, the intra picture prediction unit (<NUM>) generates a block of the same size and shape of the block under reconstruction, using surrounding already reconstructed information fetched from the current (partly reconstructed) picture (<NUM>).

In such a case, a Motion Compensation Prediction unit (<NUM>) can access reference picture memory (<NUM>) to fetch samples used for prediction. After motion compensating the fetched samples in accordance with the symbols (<NUM>) pertaining to the block, these samples can be added by the aggregator (<NUM>) to the output of the scaler / inverse transform unit (in this case called the residual samples or residual signal) so to generate output sample information. The addresses within the reference picture memory form where the motion compensation unit fetches prediction samples can be controlled by motion vectors, available to the motion compensation unit in the form of symbols (<NUM>) that can have, for example X, Y, and reference picture components. Motion compensation also can include interpolation of sample values as fetched from the reference picture memory when sub-sample exact motion vectors are in use, motion vector prediction mechanisms, and so forth.

Video compression technologies can include in-loop filter technologies that are controlled by parameters included in the coded video bitstream and made available to the loop filter unit (<NUM>) as symbols (<NUM>) from the parser (<NUM>), but can also be responsive to meta-information obtained during the decoding of previous (in decoding order) parts of the coded picture or coded video sequence, as well as responsive to previously reconstructed and loop-filtered sample values.

Once a coded picture is fully reconstructed and the coded picture has been identified as a reference picture (by, for example, parser (<NUM>)), the current reference picture (<NUM>) can become part of the reference picture buffer (<NUM>), and a fresh current picture memory can be reallocated before commencing the reconstruction of the following coded picture.

The video decoder (<NUM>) may perform decoding operations according to a predetermined video compression technology that may be documented in a standard, such as ITU-T Rec. The coded video sequence may conform to a syntax specified by the video compression technology or standard being used, in the sense that it adheres to the syntax of the video compression technology or standard, as specified in the video compression technology document or standard and specifically in the profiles document therein.

Additional data can be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, and so on.

<FIG> is a functional block diagram of a video encoder (<NUM>) according to an embodiment.

The encoder (<NUM>) may receive video samples from a video source (<NUM>) (that is not part of the encoder) that may capture video image(s) to be coded by the encoder (<NUM>).

The video source (<NUM>) may provide the source video sequence to be coded by the encoder (<NUM>) in the form of a digital video sample stream that can be of any suitable bit depth (for example: <NUM> bit, <NUM> bit, <NUM> bit,. <NUM> Y CrCB, RGB,. ) and any suitable sampling structure (for example Y CrCb <NUM>:<NUM>:<NUM>, Y CrCb <NUM>:<NUM>:<NUM>).

According to an embodiment, the encoder (<NUM>) may code and compress the pictures of the source video sequence into a coded video sequence (<NUM>) in real time or under any other time constraints as required by the application. Enforcing appropriate coding speed is one function of Controller (<NUM>). Controller controls other functional units as described below and is functionally coupled to these units. Parameters set by controller can include rate control related parameters (picture skip, quantizer, lambda value of rate-distortion optimization techniques,. A person skilled in the art can readily identify other functions of controller (<NUM>) as they may pertain to video encoder (<NUM>) optimized for a certain system design.

Some video encoders operate in what a person skilled in the art readily recognizes as a "coding loop. " As an oversimplified description, a coding loop can consist of the encoding part of an encoder (<NUM>) ("source coder" henceforth) (responsible for creating symbols based on an input picture to be coded, and a reference picture(s)), and a (local) decoder (<NUM>) embedded in the encoder (<NUM>) that reconstructs the symbols to create the sample data that a (remote) decoder also would create (as any compression between symbols and coded video bitstream is lossless in the video compression technologies considered in the disclosed subject matter). That reconstructed sample stream is input to the reference picture memory (<NUM>). As the decoding of a symbol stream leads to bit-exact results independent of decoder location (local or remote), the reference picture buffer content is also bit exact between local encoder and remote encoder. This fundamental principle of reference picture synchronicity (and resulting drift, if synchronicity cannot be maintained, for example because of channel errors) is well known to a person skilled in the art.

The operation of the "local" decoder (<NUM>) can be the same as of a "remote" decoder (<NUM>), which has already been described in detail above in conjunction with <FIG>. Briefly referring also to <FIG>, however, as symbols are available and en/decoding of symbols to a coded video sequence by entropy coder (<NUM>) and parser (<NUM>) can be lossless, the entropy decoding parts of decoder (<NUM>), including channel (<NUM>), receiver (<NUM>), buffer (<NUM>), and parser (<NUM>) may not be fully implemented in local decoder (<NUM>).

As part of its operation, the source coder (<NUM>) may perform motion compensated predictive coding, which codes an input frame predictively with reference to one or more previously-coded frames from the video sequence that were designated as "reference frames. " In this manner, the coding engine (<NUM>) codes differences between pixel blocks of an input frame and pixel blocks of reference frame(s) that may be selected as prediction reference(s) to the input frame.

The local video decoder (<NUM>) may decode coded video data of frames that may be designated as reference frames, based on symbols created by the source coder (<NUM>). When the coded video data may be decoded at a video decoder (not shown in <FIG>), the reconstructed video sequence typically may be a replica of the source video sequence with some errors. The local video decoder (<NUM>) replicates decoding processes that may be performed by the video decoder on reference frames and may cause reconstructed reference frames to be stored in the reference picture cache (<NUM>). In this manner, the encoder (<NUM>) may store copies of reconstructed reference frames locally that have common content as the reconstructed reference frames that will be obtained by a far-end video decoder (absent transmission errors).

That is, for a new frame to be coded, the predictor (<NUM>) may search the reference picture memory (<NUM>) for sample data (as candidate reference pixel blocks) or certain metadata such as reference picture motion vectors, block shapes, and so on, that may serve as an appropriate prediction reference for the new pictures.

The controller (<NUM>) may manage coding operations of the video coder (<NUM>), including, for example, setting of parameters and subgroup parameters used for encoding the video data.

The entropy coder translates the symbols as generated by the various functional units into a coded video sequence, by loss-less compressing the symbols according to technologies known to a person skilled in the art as, for example Huffman coding, variable length coding, arithmetic coding, and so forth.

The transmitter (<NUM>) may buffer the coded video sequence(s) as created by the entropy coder (<NUM>) to prepare it for transmission via a communication channel (<NUM>), which may be a hardware/software link to a storage device that may store the encoded video data.

The controller (<NUM>) may manage operation of the encoder (<NUM>). For example, pictures often may be assigned as one of the following frame types:.

Source pictures commonly may be subdivided spatially into a plurality of sample blocks (for example, blocks of <NUM> × <NUM>, <NUM> × <NUM>, <NUM> × <NUM>, or <NUM> × <NUM> samples each) and coded on a block-by-block basis. Pixel blocks of P pictures may be coded non-predictively, via spatial prediction or via temporal prediction with reference to one previously coded reference pictures. Blocks of B pictures may be coded non-predictively, via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

The video coder (<NUM>) may perform coding operations according to a predetermined video coding technology or standard, such as ITU-T Rec. In its operation, the video coder (<NUM>) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence.

The video coder (<NUM>) may include such data as part of the coded video sequence. Additional data may comprise temporal/spatial/SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, Supplementary Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, and so on.

<FIG> is a diagram of intra prediction modes in VVC Draft <NUM>.

In VVC Draft <NUM>, there is a total of <NUM> intra prediction modes as shown in <FIG>, among which mode <NUM> (<NUM>) is a horizontal mode, mode <NUM> (<NUM>) is a vertical mode, and mode <NUM> (<NUM>), mode <NUM> (<NUM>) and mode <NUM> (<NUM>) are diagonal modes. Modes -<NUM> to <NUM> and modes <NUM> to <NUM> are called Wide-Angle Intra Prediction (WAIP) modes.

Thirty-five HEVC intra prediction modes are included in VVC Draft <NUM>, and mode numbers of these <NUM> HEVC modes are <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In VVC Draft <NUM>, a size of an MPM list is still <NUM>, and a MPM list generation process is the same as HEVC. A difference is that an "offset" is changed to <NUM>, and a variable "mod" is changed to <NUM> because there are <NUM> signaled modes in VVC Draft <NUM>.

For mode coding, firstly, one MPM flag is signaled to indicate whether a current mode belongs to the MPM list. If the MPM flag is true, then a truncated unary code is used to signal an MPM index. If the MPM flag is false, then <NUM> bit fix length coding is used to signal remaining modes.

The following clause from VVC Draft <NUM> describes a luma intra mode coding process:.

The variable IntraPredModeY[ x ][ y ] with x = xPb. xPb + cbWidth - <NUM> and y = yPb. yPb + cbHeight - <NUM> is set to be equal to IntraPredModeY[ xPb ][ yPb ].

In the development of VVC Draft <NUM>, an MPM list with a size of <NUM> was proposed. Planar and DC modes are included in the MPM list. Two neighboring modes, left and above modes, are used to generate a remaining <NUM> MPMs.

However, in VVC Draft <NUM>, the number of the available intra prediction modes is more than <NUM>, which costs many bits to signal. There is a strong correlation between a current block and its neighboring blocks, which may be used to reduce the number of signaled intra prediction modes for the current block.

Proposed methods below may be used separately or combined in any order.

In the description below, if one mode is not a planar or DC mode, or one mode is generating prediction samples according a given prediction direction, such as intra prediction modes <NUM> to <NUM> and -<NUM> to -<NUM> as defined in VVC Draft <NUM>, this mode is called an angular mode.

In the description below, an allowed intra prediction mode (AIPM) set is defined as one mode set with modes that can be used for intra prediction of a current block, and a disallowed intra prediction mode (DIPM) set is defined as one mode set with modes that cannot be signaled or used for intra prediction of the current block.

Two variables are used in this document, offset and mod. The values of these two variables can have the following two sets:.

In an embodiment, there are two intra prediction mode sets for each block, which are an AIPM set and a DIPM set. For each block, modes in these two mode sets may be different depending on coded information of neighboring blocks and/or a current block, and may include but not be limited to intra prediction modes of neighboring blocks, intra prediction modes of current blocks, an aspect ratio, a coded block flag (CBF), primary and/or secondary transform types, neighboring reconstructed samples and so on.

In an embodiment, the modes in the AIPM set and the DIPM sets are dependent on the intra prediction modes of the neighboring blocks.

In an embodiment, neighboring modes are included in the AIPM set but not included in the DIPM set.

In an embodiment, blocks with a same aspect ratio or a same width and/or height can have a different AIPM set and/or a different DIPM set.

In an embodiment, for each angular neighboring mode, denoted by ang_mode, certain modes can be derived by the below equations <NUM> and <NUM>, and the derived modes are included in the AIPM set but not included in the DIPM set. <MAT> <MAT>.

In Equations <NUM> and <NUM>, diff is a variable, and is a positive integer or zero. In an example, diff can be any value equal to or less than <NUM>. In another example, diff can be any value equal to or less than <NUM>. In still another example, diff can be any value in set {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>}.

In an embodiment, to reduce the complexity of reconstructing the AIPM set, a number of derived modes are restricted by a threshold, denoted by Thres. Thres can be any positive integer, such as <NUM>, <NUM> or <NUM>.

In an embodiment, the modes in the AIPM and DIPM sets are dependent on the inter prediction modes of the neighboring blocks.

In an embodiment, the modes in the AIPM and DIPM sets are dependent on whether the neighboring blocks are intra coded, or inter coded, or coded by an Intra Block Copy (IBC) mode, or coded by a MERGE mode, or coded by a SKIP mode, or coded by another coding mode.

In an embodiment, reconstructed pixels of neighboring blocks are used to derive allowed and non-allowed intra prediction mode sets.

In an embodiment, a gradient of neighboring reconstructed samples is used to derive the modes in the AIPM and DIPM sets. The gradient can be computed by one of the following methods including, but not limited to: a first-order gradient method, a second-order gradient method, and a biconjugate gradient method.

In an embodiment, an edge detection method or an image feature detection method can be used to derive the modes in the AIPM and DIPM sets. The edge detection method includes, but is not limit to, one of a Sobel operator, a Laplace operator, a Canny edge detector, a Kayyali operator, a SUSAN corner detector, and so on.

In an embodiment, the number of modes included in the AIPM and DIPM sets are predefined and fixed for all blocks.

In an embodiment, the number of modes included in the AIPM set is denoted by S, and S is equal to M plus a power of two, for example = M + <NUM>K, where M and K are positive integers, for example, M = <NUM> and K = <NUM>. M can be no larger than <NUM>. Examples values include but are not limited to <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In an embodiment, a size of the AIPM set is denoted by S, and S is equal to M plus multiple levels of a power of two, for example S = M + <NUM>K + <NUM>L, where M, K, and L are positive integers, for example M = <NUM>, K = <NUM>, L = <NUM>. M can be no larger than <NUM>. Examples values include but are not limited to <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

In an embodiment, the number of modes included in the AIPM and DIPM sets are predefined and fixed for each block size, or each block aspect ratio, or each block shape. However, the number of modes included in the AIPM and DIPM sets can be different for different block sizes, or a different block aspect ratio, or a different block shape.

In an embodiment, when the size of the AIPM set is S and the number of derived intra prediction modes from neighboring modes are less than S, default modes are used to fill the AIPM set.

In an embodiment, all HEVC intra prediction modes are included in the default modes. In an example, S is equal to or larger than <NUM>.

In an embodiment, all intra prediction modes associated with even mode indices are included in the default modes. In an example, S is equal to or larger than <NUM>.

In an embodiment, angular modes associated with odd mode indices are included into default modes after HEVC intra prediction modes have been included.

In an embodiment, when the size of the AIPM set is <NUM>, the default modes are predefined as follows {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>}.

In an embodiment, when the size of the AIPM set is larger than <NUM>, all HEVC intra prediction modes, or all intra prediction modes associated with even mode indices, or all intra prediction modes associated with odd mode indices, are always included in the AIPM set, but not included in the DIPM set.

In an embodiment, for the AIPM set, it can be further split into two lists, a primary MPM list and a non-MPM list, and a size of the non-MPM list is a power of <NUM>.

In an embodiment, to code a mode in the AIPM set, firstly, one MPM flag is signaled to indicate whether the current mode belongs to the primary MPM list. If the MPM flag is true, a truncated unary code is used to signal the MPM index. Otherwise, fix length coding is used to signal the mode in the non-MPM list.

Twenty-eight or thirty wide angles and respective wide angular intra prediction modes are added into a table of original angles and respective original angular intra prediction modes, according to an aspect ratio of a current block.

In an embodiment, <NUM> or <NUM> wide angles and respective wide angular intra prediction modes are added into a bottom-left direction of the current block (e.g., a bottom edge <NUM> of <FIG>), and another <NUM> or <NUM> wide angles and respective wide angular intra prediction modes are added into a top-right direction (e.g., a right edge <NUM> of <FIG>) of the current block. Implementations of examples are shown in Tables <NUM>-<NUM> below.

An angle table for wide angles together with original angles are shown as follows.

In an example, an angle table of <NUM> angles (angTable[<NUM>]) may include angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>}, in which angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>} are original angles and angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>} are wide angles.

In other words, each of the angles may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

As an example useful for understanding the invention but do not form a part of the present invention, Table <NUM> may be an example of such an angle table with respective intra prediction modes in VVC having <NUM> original angles and <NUM> respective original angular intra prediction modes, to which <NUM> wide angles and <NUM> respective wide angular intra prediction modes are added:.

predModeIntra denotes intra prediction modes in VVC, and intraPredAngle denotes intra prediction angles.

In another example, an angle table of <NUM> angles (angTable[<NUM>]) may include angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>}, in which angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>} are original angles and angles {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>} are wide angles.

In other words, each of the angles may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

Table <NUM> is an angle table according to the claimed invention with respective intra prediction modes in VVC having <NUM> original angles and <NUM> respective original angular intra prediction modes, to which <NUM> wide angles and <NUM> respective wide angular intra prediction modes are added:.

The following text describes text changes (with strikethrough and underlining) to VVC Draft <NUM>, using the above-discussed embodiments:.

Outputs of this process are the modified intra prediction Mode predModeIntra and the predicted samples predSamples[ x ][ y ], with x = <NUM>. nTbW + <NUM>, y = <NUM>. nTbH + <NUM>.

The variable whRatio is set equal to mine abs( Log2( nTbW / nTbH ) ), <NUM> ).

For non-square blocks (nTbW is not equal to nTbH), the intra prediction mode predmodelntra is modified as follows:.

Table <NUM>-<NUM> specifies the mapping table between predModeIntra and the angle parameter intraPredAngle and Figure <NUM>-<NUM> illustrates the intra prediction angles for each angle parameter.

<FIG> is a flowchart illustrating a method (<NUM>) of controlling intra prediction for decoding of a video sequence, according to an embodiment. In some implementations, one or more process blocks of <FIG> may be performed by the decoder (<NUM>). In some implementations, one or more process blocks of <FIG> may be performed by another device or a group of devices separate from or including the decoder (<NUM>), such as the encoder (<NUM>).

Referring to <FIG>, in a first block (<NUM>), the method (<NUM>) includes determining a ratio of a width to a height of a coding unit.

In a second block (<NUM>), the method (<NUM>) includes, based on the determined ratio being different than one, adding, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles.

A number of the first wide angles added to the table may be <NUM>. Each of the intra prediction angles included in the table may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}, and each of the first wide angles added to the table may have the angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

A number of the second wide angles added to the table may be <NUM>. Each of the intra prediction angles included in the table may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}, and each of the second wide angles added to the table may have the angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

A number of the first wide angles added to the table may be <NUM>. Each of the intra prediction angles included in the table may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}, and each of the first wide angles added to the table may have the angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

A number of the second wide angles added to the table may be <NUM>. Each of the intra prediction angles included in the table may have an angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}, and each of the second wide angles added to the table may have the angular direction α with tan(α) equal to {<NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>}.

A first number of the plurality of intra prediction modes included in the table may be <NUM>, a second number of the additional intra prediction modes added to the table may be <NUM>, and the table may include Table <NUM> above.

In a third block (<NUM>), the method (<NUM>) includes selecting, for decoding the video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table.

Although <FIG> shows example blocks of the method (<NUM>), in some implementations, the method (<NUM>) may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in <FIG>. Additionally, or alternatively, two or more of the blocks of the method (<NUM>) may be performed in parallel.

Further, the proposed methods may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In an example, the one or more processors execute a program that is stored in a non-transitory computer-readable medium to perform one or more of the proposed methods.

<FIG> is a simplified block diagram of an apparatus (<NUM>) for controlling intra prediction for decoding of a video sequence, according to an embodiment.

Referring to <FIG>, the apparatus (<NUM>) includes determining code (<NUM>), adding code (<NUM>), and selecting code (<NUM>).

The determining code (<NUM>) is configured to determine a ratio of a width to a height of a coding unit.

The adding code (<NUM>) is configured to, based on the determined ratio being different than one, add, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles.

The selecting code (<NUM>) is configured to select, for decoding the video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table.

<FIG> is a diagram of a computer system (<NUM>) suitable for implementing embodiments.

The components shown in <FIG> for computer system (<NUM>) are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing embodiments.

Input human interface devices may include one or more of (only one of each depicted): keyboard (<NUM>), mouse (<NUM>), trackpad (<NUM>), touch screen (<NUM>), data-glove (<NUM>), joystick (<NUM>), microphone (<NUM>), scanner (<NUM>), camera (<NUM>).

Such human interface output devices may include tactile output devices (for example tactile feedback by the touch-screen (<NUM>), data-glove (<NUM>), or joystick (<NUM>), but there can also be tactile feedback devices that do not serve as input devices), audio output devices (such as: speakers (<NUM>), headphones (not depicted)), visual output devices (such as screens (<NUM>) to include cathode ray tube (CRT) screens, liquid-crystal display (LCD) screens, plasma screens, organic light-emitting diode (OLED) screens, each with or without touch-screen input capability, each with or without tactile feedback capability-some of which may be capable to output two dimensional visual output or more than three dimensional output through means such as stereographic output; virtual-reality glasses (not depicted), holographic displays and smoke tanks (not depicted)), and printers (not depicted).

Computer system (<NUM>) can also include interface(s) to one or more communication networks. Networks can for example be wireless, wireline, optical. Networks can further be local, wide-area, metropolitan, vehicular and industrial, real-time, delay-tolerant, and so on. Examples of networks include local area networks such as Ethernet, wireless LANs, cellular networks to include global systems for mobile communications (GSM), third generation (<NUM>), fourth generation (<NUM>), fifth generation (<NUM>), Long-Term Evolution (LTE), and the like, TV wireline or wireless wide area digital networks to include cable TV, satellite TV, and terrestrial broadcast TV, vehicular and industrial to include CANBus, and so forth. Certain networks commonly require external network interface adapters that attached to certain general purpose data ports or peripheral buses ((<NUM>)) (such as, for example universal serial bus (USB) ports of the computer system (<NUM>); others are commonly integrated into the core of the computer system (<NUM>) by attachment to a system bus as described below (for example Ethernet interface into a PC computer system or cellular network interface into a smartphone computer system). Using any of these networks, computer system (<NUM>) can communicate with other entities. Such communication can be uni-directional, receive only (for example, broadcast TV), uni-directional send-only (for example CANbus to certain CANbus devices), or bi-directional, for example to other computer systems using local or wide area digital networks. Certain protocols and protocol stacks can be used on each of those networks and network interfaces as described above.

The core (<NUM>) can include one or more Central Processing Units (CPU) (<NUM>), Graphics Processing Units (GPU) (<NUM>), specialized programmable processing units in the form of Field Programmable Gate Areas (FPGA) (<NUM>), hardware accelerators (<NUM>) for certain tasks, and so forth. These devices, along with Read-only memory (ROM) (<NUM>), Random-access memory (RAM) (<NUM>), internal mass storage such as internal non-user accessible hard drives, solid-state drives (SSDs), and the like (<NUM>), may be connected through a system bus (<NUM>). Architectures for a peripheral bus include peripheral component interconnect (PCI), USB, and the like.

Transitional data can also be stored in RAM (<NUM>), whereas permanent data can be stored for example, in the internal mass storage (<NUM>).

The media and computer code can be those specially designed and constructed for the purposes of embodiments, or they can be of the kind well known and available to those having skill in the computer software arts.

Claim 1:
A method of controlling intra prediction for decoding of a video sequence, the method being performed by at least one processor, the method comprising:
determining a ratio of a width to a height of a coding unit (<NUM>);
based on the determined ratio being different than one, adding, to a table including a plurality of intra prediction modes corresponding to intra prediction angles, first wide angles toward a bottom-left edge of the coding unit, second wide angles toward a top-right edge of the coding unit, and additional intra prediction modes respectively corresponding to the first wide angles and the second wide angles (<NUM>); and
selecting, for decoding the video sequence, one of the plurality of intra prediction modes and the additional intra prediction modes added to the table (<NUM>),
wherein a first number of the plurality of intra prediction modes included in the table is <NUM>,
characterized in that
a second number of the additional intra prediction modes added to the table is <NUM>, and
the table includes:

<TAB>

where predModeIntra denotes the plurality of intra prediction modes, and intraPredAngle denotes the intra prediction angles.