METHOD AND APPARATUS FOR VIDEO ENCODING - Patent application

Abstract

To provide a method and apparatus for video decoding.SOLUTION: In some embodiments, an apparatus for video decoding includes processing circuitry. The processing circuitry decodes at least one syntax element from a coded video bitstream. The at least one syntax element is indicative of a block size of a non-square block under reconstruction that has a rectangular shape. The block size includes a first size in a first dimension and a second size in a second dimension. The first size is different from the second size. The processing circuitry predicts a sample of the non-square block based on a first set of intra-frame prediction directions for the non-square block. The first set of intra-frame prediction directions does not include at least one intra-frame prediction direction in a second set of intra-frame prediction directions for a square block.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] This disclosure is a priority application of U.S. Provisional Application No. 62 / 679,664, filed June 1, 2018. Rights No. 6,399,433, filed on Oct. 23, 2003, and is hereby incorporated by reference in its entirety.

[0002] This disclosed subject matter describes embodiments generally relating to video encoding. [Background technology]

[0003] The background description provided in this specification is intended to provide a general background to the present disclosure. In light of the extent of the work described in the background section, the work of the currently signed inventors and aspects not otherwise limited as prior art at the time of filing are not expressly or implicitly admitted as prior art to the present disclosure.

[0004] Video encoding and decoding can be performed using inter-picture prediction with motion compensation. Uncompressed digital video may include a sequence of pictures, each having a spatial dimension, e.g., 1920x1080 luminance samples and associated chrominance samples. The sequence of pictures may have a fixed or variable picture rate (also informally called frame rate), e.g., 60 pictures per second or 60 Hz. Uncompressed video has high bitrate requirements. For example, 1080r604:2:0 video (1920x1080 luminance sample resolution at 60 Hz frame rate) with 8 bits per sample requires a bandwidth approaching 1.5 Gbit / s. One hour of such video requires more than 600 GB of storage space.

[0005] Video encoding and decoding has one objective to reduce redundancy in the video signal input through compression. Compression comes at the expense of bandwidth or storage space as mentioned above. Requirements, and in some circumstances by two or more orders of magnitude. Lossless compression, lossy compression, and combinations of both can be used. Lossless compression refers to techniques that reconstruct an exact copy of the original signal from the original signal that has been compressed. When lossy compression is used, the reconstructed signal may differ from the original signal, but the distortion between the original and reconstructed signals is small enough that the reconstructed signal is Target Applications For video, lossy compression is used to a large extent. The amount of acceptable distortion is application dependent, e.g. users of consumer streaming media applications will tolerate higher distortion than users of television contribution applications. The compression ratio achieved will reflect that the higher the permitted / tolerable distortion, the higher the compression ratio.

[0006] Video encoders and decoders may utilize techniques from a number of broad categories, including, for example, motion compensation, transform, quantization, entropy coding, and so on.

[0007] Video codec techniques include a technique called intraframe coding, which represents sample values ​​without reference to samples or other data from a previously reconstructed reference picture. In some video codecs, a picture is spatially subdivided into sample blocks. A picture may be an intraframe picture if all sample blocks are coded in intraframe mode. Intraframe pictures and their derivatives, such as independent Standing A coder refresh picture can be used to reset the decoder state and therefore can be used as the first picture in a coded video bitstream and video session, or as a still picture. Samples of an intraframe block may be transformed and the transform coefficients quantized before entropy coding. Intraframe prediction can be a technique that minimizes sample values ​​in a pre-transformed domain. In some cases, the smaller the transformed DC value and the smaller the AC coefficients, the fewer bits are needed to represent the entropy coded block for a given quantization step size.

[0008] For example, MPEG-2 Generation Conventional intraframe coding known from coding techniques does not use intraframe prediction. However, new video compression techniques include techniques that attempt to predict data blocks from surrounding sample data and / or metadata obtained during spatially adjacent coding / decoding and preceding in decoding order. Such techniques are called "intraframe prediction" techniques. In at least some cases, intraframe prediction uses only reference data from the current picture being reconstructed, and does not use reference data from reference pictures.

[0009] There are various forms of intra prediction. If more than one such technique is available for a given video coding technique, the technique used in the intra prediction mode may be coded. In some cases, the mode may have sub-modes and / or parameters that are coded separately or included in the mode codeword. Which codeword is used for a given mode / sub-mode / parameter combination may affect the coding efficiency gains due to intra prediction, as may the entropy coding technique used to convert the codeword into a bitstream.

[0010] Some modes of intraframe prediction were introduced in H.264 and further subdivided in H.265. Same search This is elaborated in new coding techniques such as the Joint Examination Model (JEM), Versatile Video Coding (VVC) and Benchmark Set (BMS). Neighboring sample values ​​belonging to already available samples may be used to form a prediction block. The sample values ​​of the neighboring samples are copied into the prediction block according to a direction. The directional references used may be coded in the bitstream or predicted themselves.

[0011] Referring to FIG. 1, at the bottom right, a subset of 9 prediction directions obtained from the 35 possible prediction directions of H.265 is depicted. The point where the arrows converge (101) represents the sample being predicted. The arrows represent the direction in which the sample is predicted. For example, the arrow (102) indicates that the sample (101) is predicted depending on one or more samples at the top right and at an angle of 45 degrees from the horizontal. Similarly, the arrow (103) indicates that the sample (101) is predicted depending on one or more samples at an angle of 22.5 degrees from the horizontal to the bottom right of the sample (101).

[0012] Continuing to refer to FIG. 1, at the top left, a square block (104) of 4×4 samples is depicted (indicated by a dashed bold line). The square block (104) contains 16 samples, each labeled with an “S”, its position in the Y dimension (e.g., row index) and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample in the Y dimension (from the top) and the first sample in the X dimension (from the left). Similarly, sample S44 is the fourth sample in both the Y and X dimensions of the block (104). Since the size of the block (104) is 4×4 samples, sample S44 is at the bottom right. Also shown are reference samples that follow a similar numbering scheme. The reference samples are labeled with R, its Y position (e.g., row index) and its X position (column index) relative to the block (104). In both H.264 and H.265, the predicted samples are adjacent in the block being reconstructed. Therefore, there is no need to use negative values.

[0013] Intra-frame picture prediction is SignaledThis is done by copying reference sample values ​​from adjacent samples according to the prediction direction. For example, suppose the coded video bitstream contains a signaling indicating, for this block, the prediction direction that corresponds to the arrow (102), i.e. predict this sample according to one or more prediction samples at the top right and at an angle of 45 degrees from the horizontal. In that case, samples S41, S32, S23, and S14 are predicted according to the same R05. Then, sample S44 is predicted according to R08.

[0014] In some cases, values ​​of multiple reference samples may be combined, for example by interpolation, to calculate a reference sample, especially when the orientation is not evenly divisible by 45 degrees.

[0015] As video coding techniques develop, the number of possible directions is increasing. In H.264 (2003), nine different directions can be represented. In H.265 (2013), this increases to 33, and JEM / VVC / BMS can support up to 65 directions. Experiments have already been done to know the most likely directions, and entropy coding techniques are used to represent these possible directions with fewer bits, if one is willing to accept a penalty for the less likely directions. Also, the direction itself can sometimes be predicted from the neighboring directions used in adjacent already decoded blocks.

[0016] FIG. 2 is a schematic diagram 201 illustrating the 67 prediction modes from JEM to show the increasing number of prediction directions over time.

[0017] The mapping of intraframe prediction direction bits to indicate direction in a coded video bitstream may vary across different video coding technologies. ,example For example, a simple direct mapping from prediction direction to intra-frame prediction mode to codeword is from , the most likely modes and similar techniques involve complex self-adaptive schemes ranging fromThose skilled in the art are familiar with these techniques. However, in all cases, some directions are statistically less likely to occur in the video content than others. Since the goal of video compression is to reduce redundancy, a well-functioning video coding technique will represent these less likely directions with more bits than the more likely directions. Summary of the Invention

[0018] Aspects of the present disclosed subject matter provide a method and apparatus for video decoding. In some embodiments, the apparatus for video decoding includes a processing circuit for decoding at least one bitstream of an encoded video signal. The processing circuit includes a processor for processing at least one bitstream of an encoded video signal. Syntax Decrypt the at least one element. Syntax The element specifies the block size of a non-square block with a rectangular shape that is being reconstructed. The block size is the first size in the first dimension. Z and and a second size in a second dimension, the first size being different from the second size. The processing circuit predicts samples for the non-square block based on a first set of intra prediction directions for the non-square block, the first set of intra prediction directions not including at least one intra prediction direction in the second set of intra prediction directions for the square blocks.

[0019] In some embodiments, the at least one intra prediction direction in the second set of intra prediction directions covers a sub-range of an angular range covered by the second set of intra prediction directions, in some examples, the sub-range includes a first end of the angular range.

[0020] In some embodiments, the intra prediction modes used for the first set of intra prediction directions do not include at least one intra prediction mode used for the at least one intra prediction direction in the second set of intra prediction directions.

[0021] In some embodiments, at least one intra prediction mode used for the at least one intra prediction direction in the second set of intra prediction directions is assigned to at least one intra prediction direction in the first set of intra prediction directions, and the at least one intra prediction direction in the first set of intra prediction directions is not included in the second set of intra prediction directions.

[0022] In some embodiments, in a combined angular range covered by the first set of intra prediction directions and the at least one intra prediction direction in the second set of intra prediction directions, the at least one intra prediction direction in the first set of intra prediction directions is covered by a sub-range that includes a first end of the combined angular range, and the at least one intra prediction direction in the second set of intra prediction directions is covered by another sub-range that includes a second end of the combined angular range.

[0023] In some embodiments, a first angular range is covered by the first set of intra prediction directions, a second angular range is covered by the second set of intra prediction directions, and a sub-range of the first angular range covered by the at least one intra prediction direction in the first set of intra prediction directions is outside the second angular range.

[0024] In some embodiments, the number of the at least one intra prediction direction in the first set of intra prediction directions is equal to the number of the at least one intra prediction direction in the second set of intra prediction directions.

[0025] In some embodiments, the number of intra prediction modes used for the second set of intra prediction directions for the square blocks is equal to the number of intra prediction modes used for the first set of intra prediction directions for the non-square blocks.

[0026] In some embodiments, the at least one intra prediction direction in the second set of intra prediction directions is based on a shape of the non-square block.

[0027] In some embodiments, the at least one intra prediction direction in the second set of intra prediction directions is based on an aspect ratio of the non-square block.

[0028] Each aspect of the present disclosure further provides a non-transitory computer-readable storage medium having a program stored thereon, the program being capable of performing any of the methods for video decoding when executed by at least one processor for video decoding. [Brief description of the drawings]

[0029] Based on the following detailed description and drawings, Object Other features, properties and various advantages of the present invention will become more apparent in the following drawings. [Figure 1] FIG. 2 is a schematic diagram of an exemplary intra-frame prediction mode. [Diagram 2] FIG. 2 is another diagram of an example intra-frame prediction mode. [Diagram 3] FIG. 3 is a schematic block diagram of a communication system (300) according to one embodiment. [Figure 4] FIG. 4 is a schematic block diagram of a communication system (400) according to one embodiment. [Diagram 5] FIG. 2 is a schematic block diagram of a decoder according to one embodiment; [Figure 6] FIG. 2 is a schematic block diagram of an encoder according to an embodiment; [Figure 7] 4 shows a block diagram of an encoder according to another embodiment; [Figure 8] 4 shows a block diagram of a decoder according to another embodiment; [Figure 9] 2 shows a schematic diagram of intra-frame prediction of samples in non-square blocks according to one embodiment; [Figure 10] 2 shows a schematic diagram of intra-frame prediction of samples in non-square blocks according to one embodiment; [Figure 11] 2 shows a schematic diagram of intra-frame prediction of samples in non-square blocks according to one embodiment; [Figure 12] 12 shows a flowchart outlining a process (1200) according to some embodiments of the present disclosure. [Figure 13] FIG. 1 is a schematic diagram of a computer system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Embodiments of the present disclosure relate, for example, to improving intra-frame prediction of non-square blocks by referencing reference samples that are spatially close to the block being reconstructed. In some implementations, the process also minimizes the number of directions used. do This is carried out by:

[0031] FIG. 3 shows a schematic block diagram of a communication system (300) according to an embodiment of the present disclosure. The communication system (300) includes a plurality of terminal devices that can communicate with each other, for example, via a network (350). For example, the communication system (300) includes a first pair of terminal devices (310) and (320) that are connected to each other via the network (350). In the example shown in FIG. 3, the first pair of terminal devices (310) and (320) perform unidirectional data transmission. For example, the terminal device (310) may encode video data (a video picture stream captured by the terminal device (310)) for transmission to another terminal (320) via the network (350). The encoded video data may be transmitted in the form of one or more encoded video bitstreams. The terminal device (320) may receive the encoded video data from the network (350), decode the encoded data, reconstruct the video pictures, and display the video pictures according to the reconstructed video data. One-way data transmission is common, such as in media service applications.

[0032] In another example, the communication system (300) includes a second pair of terminals (330) and (340) performing bidirectional transmission of encoded video data, which may occur, for example, during a video conference. In the case of bidirectional transmission of data, each of the terminal devices (330) and (340) may encode video data (video picture streams captured by the terminal devices) for transmission to the other of the terminal devices (330) and (340) over the network (350). Each of the terminal devices (330) and (340) may also receive encoded video data transmitted by the other of the terminal devices (330) and (340), decode the encoded data to recover the video pictures, and display the video pictures on an accessible display device in response to the recovered video data.

[0033] In the example shown in FIG. 3, the terminal devices (310), (320), (330), and (340) may be depicted as a server, a personal computer, and a smartphone, although the principles of the present disclosure are not so limited. The embodiments of the present disclosure may be applied to a laptop computer, a tablet, a media player, and / or a specialized video conferencing device. The network (350) may represent any number of networks that transmit encoded video data between the terminal devices (310), (320), (330), and (340), including, for example, wired and / or wireless communication networks. The communication network (350) may exchange data over circuit-switched and / or packet-switched channels. Exemplary networks include a telecommunications network, a local area network, a wide area network, and / or the Internet. For purposes of discussion of the present application, the architecture and topology of the network (350) is not important to the operation of the present disclosure, unless otherwise described herein below.

[0034] Disclosure ObjectAs an example of the application of the present invention, FIG. 4 shows a diagram of an example of the arrangement of a video encoder and a decoder in a stream transmission environment. Object It equally applies to other applications that support video, including, for example, video conferencing, digital television, and storage of compressed video on digital media including CDs, DVDs, memory sticks, and the like.

[0035] The streaming system may include a capture subsystem (413), which may include a video source (401), e.g., a digital camera, for constructing an uncompressed video picture stream (402). In an example, the video picture stream (402) includes samples captured by the digital camera. The video picture stream (402), depicted as a bold line to emphasize its high amount of data compared to the encoded video data (404) (or encoded video bitstream), may be processed by an electronic device (420) that includes a video encoder (403) connected to the video source (401). The video encoder (403) may be any of the components of the disclosure described in more detail below. Object To realize or perform each aspect of the present invention, hardware, software, or a combination thereof may be included. toThe encoded video data (404) (or encoded video bitstream (404)), depicted as thin lines to emphasize the low amount of data compared to the stream (402), may be stored in a stream server (405) for later use. One or more stream client subsystems, such as the client subsystems (406) and (408) of FIG. 4, may access the stream server (405) to retrieve copies (407) and (409) of the encoded video data (404). The client subsystem (406) may include a video decoder (410), for example in an electronic device (430). The video decoder (410) decodes the incoming copy of the encoded video data (407) and constructs an outgoing video picture stream (411) that can be displayed on a display (412) (e.g., a screen) or other display device (not shown). A streaming transmission system may encode video bitstreams (403), (407), (409) (e.g., video bitstreams) that are encoded according to a video encoding / compression standard. Examples of these standards include ITU-T H.265 Recommendation As an example, a video coding standard under development is informally called Versatile Video Coding, or VVC. Object may be used in the context of VVC.

[0036] It should be noted that electronics (420) and (430) may include other components (not shown). For example, electronics (420) may include a video decoder (not shown), and electronics (430) may similarly include a video encoder (not shown).

[0037] 5 shows a block diagram of a video decoder (510) according to an embodiment of the present disclosure. The video decoder (510) may be included in an electronic device (530). The electronic device (530) may include a receiver (531) (e.g., receiving circuitry). The video decoder (510) may be used in place of the video decoder (410) in the example shown in FIG. 4.

[0038] The receiver (531) may receive one or more coded video sequences to be decoded by the video decoder (510), in the same or another embodiment, one coded video sequence at a time, with the decoding of each coded video sequence being independent of the other coded video sequences. The coded video sequences may be received from a channel (501), which may be a hardware / software link to a storage device that stores the coded video data. The receiver (531) may receive coded video data and other data, such as coded audio data and / or auxiliary data streams, which may be forwarded to a respective using entity (not shown). The receiver (531) may separate the coded video sequences from other data. To prevent network jitter, a buffer memory (515) may be connected between the receiver (511) and the entropy decoder / parser (520) (hereafter referred to as the "parser"). In some applications, the buffer memory (515) is part of the video decoder (510). In other applications, the buffer memory (515) may be external to the video decoder (510) (not shown). In further applications, there may be a buffer memory (not shown) external to the video decoder (510) to prevent network jitter, and there may be another buffer memory (515) within the video decoder (510), for example, to handle playback timing. If the receiver (531) receives data from a store / forward device with sufficient bandwidth and controllability, or from an isochronous network, the buffer memory (515) may not be needed, or the buffer memory (515) may be small. For example, for use with the Internet's best packet network, the buffer memory (515) may be needed, and the buffer memory (515) may be relatively large and advantageously have a self-adaptive size, and may be implemented at least in part in an operating system or similar component (not shown) external to the video decoder (510).

[0039] The video decoder (510) may include a parser (520) to reconstruct symbols (521) from the encoded video sequence. These categories of symbols may include information for managing the operation of the video decoder (510) and information for controlling a display device (512) that is not an integral part of the electronic device (530) but is connected to the electronic device (530), as shown in FIG. 5. The control information used for one or more display devices may be in the form of a supplemental enhancement information (SEI message) or a video usability information (VUI) parameter set fragment (not shown). The parser (520) may perform parsing / entropy decoding on the received encoded video sequence. The encoding of the encoded video sequence may follow a video coding technique or standard and may follow various principles including variable length coding, Elfman coding, arithmetic coding with or without context sensitivity, etc. The parser (520) may extract a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder from the encoded video sequence based on at least one parameter corresponding to the group. The subgroups may include groups of pictures (GOPs), pictures, tiles, slices, macroblocks, coding units (CUs), blocks, transform units (TUs), prediction units (PUs), etc. The parser (520) may also extract, for example, transform coefficients, quantizer parameter values, motion vectors, etc. from the coded video sequence information.

[0040] The parser (520) can construct symbols (521) by performing entropy decoding / parsing operations on the video sequence received from the buffer memory (515).

[0041] Depending on the type of coded video picture or other portion (e.g., inter-frame vs. intra-frame pictures, inter-frame vs. intra-frame blocks) and other factors, the reconstruction of the symbols (521) may involve a number of different units. Which units they relate to, and the form they relate to, may be controlled by subgroup control information that the parser (520) parses from the coded video sequence. For simplicity, the flow of such subgroup control information between the parser (520) and the following units will not be described.

[0042] In addition to the functional blocks already mentioned, the video decoder (510) may be conceptually subdivided into a number of functional units, as described below. In an actual implementation operating under commercial constraints, many of these units may interact closely with each other and may be at least partially integrated with each other. However, in the context of the disclosure, Object For purposes of explanation, the following conceptual subdivision into functional units is appropriate:

[0043] The first unit is a scalar / inverse transform unit (551), which receives quantized transform coefficients as symbol(s) (521) and control information from the parser (520), including which transform method to use, block size, quantization coefficients, quantization scaling matrix, etc. The scalar / inverse transform unit (551) can output a block containing sample values ​​that can be input to an aggregator (555).

[0044] In some cases, the output samples of the scalar / inverse transform unit (551) may belong to an intraframe coded block, i.e., a prediction block from a previously reconstructed picture. surveying does not use any prediction information from the current picture, but some previously reconstructed prediction surveying Such a block of information may be used. surveyingThe information may be provided by an intra picture prediction unit (552), which in some cases uses surrounding already reconstructed information extracted from the current picture buffer (558) to predict the size and shape of the block being reconstructed. Jibu The current picture buffer (558), for example, buffers the partially reconstructed current picture and / or the fully reconstructed current picture. In some cases, the aggregator (555) adds prediction information generated by the intra prediction unit (552) to the output sample information provided by the scaler / inverse transform unit (551) based on each sample.

[0045] In other cases, the output samples of the scalar / inverse transform unit (551) may belong to an inter-frame coded and latent motion compensated block. In such a case, the motion compensated prediction unit (553) may access the reference picture memory (557) to extract samples for prediction. After performing motion compensation on the extracted samples according to the symbols (521) belonging to the block, these samples may be added by the aggregator (555) to the output of the scalar / inverse transform unit (in this case, called residual samples or residual signals) to generate output sample information. The addresses in the reference picture memory from which the motion compensation unit (553) extracts samples may be controlled by a motion vector, which is provided to the motion compensation unit in the form of a symbol (521), which may have, for example, an X, Y, and reference picture component. When motion compensation uses a sub-sample accurate motion vector, 、 This may include interpolation of sample values ​​extracted from a reference picture memory, motion vector prediction mechanisms, etc.

[0046] The output samples of the aggregator (555) are subjected to various loop filtering techniques in a loop filter unit (556). The video compression techniques may include in-loop filtering techniques controlled by parameters contained in the coded video sequence (also called coded video bitstream) and available to the loop filter unit (556) as symbols (521) from the parser (520), but may also be responsive to meta-information obtained during decoding of a previous (in decoding order) portion of the coded picture or coded video sequence, or to previously reconstructed loop filtered sample values.

[0047] The output of the loop filter unit (556) may be a sample stream that is output to a display device (512) and stored in a reference picture memory (557) for use in subsequent inter-frame picture prediction.

[0048] Once fully reconstructed, some coded pictures can be used as reference pictures for future prediction. Once a coded picture that corresponds to a current picture is fully reconstructed, and the coded picture is recognized as a reference picture (e.g., by the parser (520)), the current picture buffer (558) becomes part of the reference picture memory (557), and a new current picture buffer can be reallocated before starting reconstruction of a later coded picture.

[0049] The video decoder (510) is, for example, ITU-TH.255 Recommendation The decoding operation may be performed according to a predetermined video compression technique in accordance with a standard. Syntax for and that the encoded video sequence conforms to a profile specified in the video compression technology or standard in use. Syntax To CompatibilityIn particular, a profile may select some tools from all tools available in a video compression technology or standard as the tools that may be used in the profile. Compliance also requires that the complexity of the encoded video sequence is within a range limited by the level of the video compression technology or standard. In some cases, the level limits the maximum picture size, the maximum frame rate, the maximum reconstructed sample rate (e.g., measured in mega samples per second), the maximum reference picture size, etc. In some cases, the limits set by the level may be further limited by the specification of a hypothetical reference decoder (HRD) and metadata governing the HRD buffer signaled in the encoded video sequence.

[0050] In one embodiment, the receiver (531) may receive the encoded video along with additional (redundant) data. The additional data may be included as part of the encoded video sequence(s). The additional data may be used by the video decoder (510) to accurately decode the data and / or more accurately reconstruct the original video data. The additional data may be, for example, temporal, spatial, or signal-to-noise ratio (SNR) related data. Expansion This may be in the form of layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0051] 6 shows a block diagram of a video encoder (603) according to an embodiment of the present disclosure. The video encoder (603) is included in an electronic device (620). The electronic device (620) includes a transmitter (640) (e.g., a transmission circuit). The video encoder (603) may be used in place of the video encoder (403) in the example shown in FIG. 4.

[0052] The video encoder (603) encodes the video transformationThe video samples may be received from a video source (601) (not part of the electronic device (620) in the example shown in FIG. 6) that may capture the video image(s) to be displayed. In another example, the video source (601) is part of the electronic device (620).

[0053] The video source (601) may provide a source video sequence in the form of a digital video sample stream to be encoded by the video encoder (603), the digital video sample stream may have any suitable bit depth (e.g. 8 bit, 10 bit, 12 bit...), any color space (e.g. BT.601, YCrCB, RGB...) and any suitable sampling configuration (e.g. YCrCb 4:2:0, YCrCb 4:4:4). In a media serving system, the video source (601) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (601) may be a local It may be a camera that captures image information as a video sequence. The video data may be provided as a number of separate pictures that, when viewed in sequence, impart motion. The pictures themselves may be organized as a spatial pixel array, and depending on the sampling configuration, color space, etc., in use, each pixel may contain one or more samples. Those skilled in the art will readily appreciate the relationship between pixels and samples. In the following discussion, the focus will be on samples.

[0054] According to one embodiment, the video encoder (603) may encode pictures of a source video sequence and compress them into an encoded video sequence (643) in real-time or under any other time constraint required by the application. Performing an appropriate encoding rate is one of the functions of the controller (650). In some cases, the controller (650) controls and is operatively connected to other functional units described below. For simplicity, the coupling connections are not shown. The controller (650) settingThe parameters to be considered are rate control related parameters (picture skip, quantizer, lambda value for rate distortion optimization techniques, etc.), picture size, Group of Pictures This may include GOP layout, maximum motion vector search range, etc. The controller (650) may be configured to include other appropriate functionality that resides in the video encoder (603) designed and optimized for a given system.

[0055] In some embodiments, the video encoder (603) is configured to operate in an encoding loop. composition As a very simplified explanation, by way of example, the encoding loop may include a source encoder (630) (e.g., responsible for constructing a symbol-like symbol stream based on an input picture to be encoded and reference picture(s)), a video encoder (603) ( local The decoder (733) may include a (remote) decoder (733) that reconstructs the symbols to construct the sample data in a manner similar to the (remote) decoder (733) of the disclosure. Object The compression between symbols and the encoded video bitstream is considered in the video compression techniques reversible The reconstructed sample stream (sample data) is input to a reference picture memory (634). The decoding of the symbol stream results in bit-accurate data that is independent of the location of the decoder (local or remote). N The result is obtained, so the contents of the reference picture memory (634) local It is bit-accurate between the encoder and the remote encoder, i.e. the reference picture samples that the prediction part of the encoder "sees" are exactly the same as the sample values ​​that the decoder "sees" when it uses the prediction in decoding. This fundamental principle of reference picture synchrony (and the drift that occurs when synchrony cannot be maintained, e.g. due to channel errors) is also used in related art.

[0056] " localThe operation of the decoder (633) may be the same as the operation of the "remote" decoder of the video decoder (510) described in detail above with reference to FIG. 5. Referring briefly to FIG. 5, when symbols are available and the entropy encoder (645) and parser (520) reversible The entropy decoding portion of the video decoder (510), including the buffer memory (515) and the parser (520), can encode / decode symbols into an encoded video sequence. local It may not be fully realized in the decoder (633).

[0057] Also, any decoder technique other than analysis / entropy decoding that exists in the decoder necessarily exists in the corresponding encoder in essentially the same functional form. For , Disclosure Object We now focus on the decoder operation. We will simplify the description of the encoder technique since it is the inverse of the decoder technique described in detail. It is only needed in certain areas and is described in more detail below.

[0058] During operation, in some examples, the source encoder (630) may perform motion-compensated predictive encoding, which performs predictive encoding on an input picture by referencing one or more previously encoded pictures from the video sequence designated as "reference pictures." In this manner, the encoding engine (632) may encode differences between pixel blocks of the input picture and pixel blocks that may be selected as the reference picture(s) of the input picture's predictive reference(s).

[0059] local The video decoder (633) may decode the encoded video data of pictures that may be designated as reference pictures based on the symbols constructed by the source encoder (630). The operation of the encoding engine (632) advantageously includes: irreversibleWhen the encoded video data is decoded in a video decoder (not shown in FIG. 6), the reconstructed video sequence may be a copy of the source video sequence, usually with some errors. The local video decoder (633) may replicate the decoding process that may be performed by the video decoder on the reference pictures and store the reconstructed reference pictures in a reference picture buffer (634). In this way, the encoder (603) can locally store copies of reconstructed reference pictures that have common content with the reconstructed reference pictures obtained by the far-end video decoder (free of transmission errors).

[0060] The predictor (635) can perform a prediction search for the coding engine (632). That is, for a new picture to be coded, the predictor (635) may search the reference picture memory (634) for sample data (as candidate reference pixel blocks) or specific metadata, such as the reference picture's motion vectors, block shapes, etc., that can be used as suitable prediction references for the new picture. The predictor (635) can operate pixel block by pixel block based on the sample blocks to find suitable prediction references. In some cases, as determined by the search results obtained by the predictor (635), the input picture may have prediction references extracted from multiple reference pictures stored in the reference picture memory (634).

[0061] The controller (650) can manage the encoding operations of the video encoder (630), for example by controlling parameters and subgroup parameters for encoding the video data. setting Includes.

[0062] An entropy encoder (645) may perform entropy coding on the output of all of the functional units mentioned above. The entropy encoder (645) performs entropy coding on the symbols generated by each functional unit according to techniques known to those skilled in the art, such as Huffman coding, variable length coding, arithmetic coding, etc. reversibleCompression converts the symbols into a coded video sequence.

[0063] The transmitter (640) may buffer the encoded video sequence(s) constructed by the entropy encoder (646) and prepare them for transmission over a communication channel (660), which may be a hardware / software link to a storage device that stores the encoded video data. The transmitter (640) may merge the encoded video data from the video encoder (630) with other data to be transmitted, such as encoded audio data and / or auxiliary data streams (sources not shown).

[0064] A controller (650) can manage the operation of the encoder (603). During encoding, the controller (650) assigns each encoded picture a particular encoding picture type, which may affect the encoding technique that may be applied to the corresponding picture. For example, pictures are typically assigned to one of the following picture types:

[0065] It may also be an intraframe picture (I-picture), a picture that is coded and decoded when no other picture in the sequence serves as a source of prediction. decoder Some video codecs allow different types of intraframe pictures, including intra-refresh ("IDR") pictures. Those skilled in the art will understand the variations of I-pictures and their corresponding applications and characteristics.

[0066] Forecast Measurement In the case where a sample value of each block is predicted by at most one motion vector and reference index, the picture may be a P picture, and may be encoded and decoded using intra-frame prediction or inter-frame prediction.

[0067] Two-way Prediction MeasurementA picture may be a B picture, which is encoded and decoded using intra-frame prediction or inter-frame prediction, in which the sample values ​​of each block are predicted by at most two motion vectors and reference indexes. Measurement A texture can use more than two reference pictures and associated metadata to reconstruct a single block.

[0068] A source picture can generally be spatially subdivided into blocks of samples (e.g., blocks of 4x4, 8x8, 4x8 or 16x16 samples) and coded block-wise. These blocks can refer to other (coded) blocks and can be predicted. measurement For example, a block of an I picture may be coded non-predictively, or a block of an I picture may be coded predictively by referring to coded blocks of the same picture. Survey mark P-picture pixel blocks are predicted through spatial or temporal prediction with reference to one previously coded reference picture. measurement Blocks in B pictures may be predicted via spatial or temporal prediction with reference to one or two previously coded reference pictures. measurement Alternatively, the encoding may be performed on the

[0069] The video encoder (603) is, for example, ITU-T H.266 Recommendation The video encoder (403) may perform encoding operations according to a given video encoding technique or standard of the input video sequence. During its operation, the video encoder (403) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence. The encoded video data may thus be encoded according to a predetermined video encoding technique or standard of the input video sequence. Syntax Fits.

[0070] In one embodiment, the transmitter (640) may transmit additional data and the encoded video. The source encoder (630) may include such data as part of the encoded video sequence. The additional data may include temporal / spatial / SNR Expansion Layers, e.g. redundant pictures, slices, and other forms of redundant data, auxiliary Expansion Information (SEI) message, Visual Usability Information (VUI) parameter set Fragment etc. may be included.

[0071] The captured video may be multiple source pictures (video pictures) that represent a time sequence. Intraframe picture prediction (commonly simplified to intraframe prediction) exploits spatial associations in a particular picture, while interframe picture prediction exploits associations (temporal or other) between pictures. In the example, a particular picture in the encoding / decoding, called the current picture, is divided into blocks. If a block in the current picture is similar to a reference block in a previously encoded and still buffered reference picture in the video, the block in the current picture can be encoded by a vector called a motion vector. The motion vector points to a reference block in the reference picture, and may have a third dimension to identify the reference picture when multiple reference pictures are used.

[0072] In some embodiments, bi-directional prediction techniques are used for inter-frame picture prediction. order Both are before the current picture in the video (but not before the order The current picture may be coded using two reference pictures, such as a first reference picture and a second reference picture, which may be in the past and future, respectively. A block in the current picture may be coded using a first motion vector pointing to a first reference block in the first reference picture and a second motion vector pointing to a second reference block in the second reference picture. A block may be predicted using a combination of the first and second reference blocks.

[0073] Also, merge The mode technique can be applied to inter-frame picture prediction to improve coding efficiency.

[0074] According to some embodiments of the present disclosure, prediction such as inter-frame picture prediction and intra-frame picture prediction is performed on a block-by-block basis. For example, according to the HEVC standard, pictures in a video picture sequence are arranged in a coding tree. -You In a picture, a picture is divided into coding tree blocks (CTUs) for compression, and the CTUs in the picture have the same size, for example, 64×64 pixels, 32×32 pixels, or 16×16 pixels. Generally, a CTU includes three coding tree blocks (CTBs), each including one luminance CTB and two chrominance CTBs. Each CTU is recursively divided into one or more coding units (CUs) in a quad tree. For example, a CTU of 64×64 pixels is divided into one CU of 64×64 pixels, or four CUs of 32×32 pixels, or sixteen CUs of 16×16 pixels. In an example, each CU is analyzed to determine a prediction type for the CU, such as an inter-frame prediction type or an intra-frame prediction type. Depending on the temporal and / or spatial predictability, the CU is divided into one or more prediction units (PUs). Generally, each PU includes a luminance prediction block (PB) and two chrominance PBs. In one embodiment, the prediction operation in coding (encoding / decoding) is performed for each prediction block. An example of a prediction block is a luma prediction block, which includes a matrix of pixel values ​​(e.g., luma values), such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, etc.

[0075] 7 shows a diagram of a video encoder (703) according to another embodiment of this disclosure. The video encoder (703) is configured to receive a processed block (e.g., a predictive block) of sample values ​​in a current video picture in a sequence of video pictures. composition4. In one embodiment, the video encoder (703) is used in place of the video encoder (403) in the example shown in FIG.

[0076] In an HEVC example, a video encoder (703) receives a processing block, e.g., a matrix of sample values, e.g., a predictive block of 8x8 samples. The video encoder (703) determines whether to optimally encode the processing block using intra mode, inter mode, or bidirectional predictive mode, e.g., by rate-distortion optimization. When encoding the processing block in intra mode, the video encoder (703) may encode the processing block into a coded picture using intra prediction techniques, and when encoding the processing block in inter mode or bidirectional predictive mode, the video encoder (703) may encode the processing block into a coded picture using inter prediction or bidirectional prediction techniques, respectively. In one video encoding technique, merge The mode may be an inter-picture prediction sub-mode, in which motion vectors are derived from one or more motion vector predictors, without borrowing any coded motion vector components outside the predictors. subject There may be a motion vector component applied to the block. In an example, the video encoder (703) may include other modules, such as a mode decision module (not shown) for determining the mode of the processing block. Components Includes.

[0077] In the example shown in FIG. 7, the video encoder (703) includes an interframe encoder (730), an intraframe encoder (722), a residual calculator (723), a switch (726), a residual encoder (724), a generalized controller (721), and an entropy encoder (725), all connected together as shown in FIG.

[0078] The inter-frame encoder (730) receives samples of a current block (e.g., a processing block), compares the current block to one or more reference blocks in a reference picture (e.g., blocks in previous and subsequent pictures), and generates inter-frame prediction information (e.g., redundant information descriptions from inter-frame coding techniques, motion vectors, merge and calculating an inter-frame prediction result (e.g., a prediction block) using any suitable technique based on the inter-frame prediction information. composition It has been done.

[0079] The intraframe encoder (722) receives samples of a current block (e.g., a processing block), in some cases compares the current block with previously coded blocks in the same picture, generates quantized coefficients after transformation, and in some cases also generates intraframe prediction information (e.g., depending on intraframe prediction direction information of one or more intraframe coding techniques). composition It has been done.

[0080] The general purpose controller (721) determines general purpose control data and controls other components of the video encoder (703) based on the general purpose control data. composition In the example, the generalized controller (721) determines the mode of the block and provides a control signal to the switch (726) based on the mode. For example, if the mode is an intra mode, the generalized controller (721) controls the switch (726) to select an intra mode result to be used by the residual calculator (723) and controls the entropy encoder (725) to select intra prediction information and include the intra prediction information in the bitstream, and if the mode is an inter mode, the generalized controller (721) controls the switch (726) to select an inter prediction result to be used by the residual calculator (723) and controls the entropy encoder (725) to select inter prediction information and include the inter prediction information in the bitstream.

[0081] The residual calculator (723) is configured to calculate the difference (residual data) between the received block and a prediction result selected from the intraframe encoder (722) or the interframe encoder (730). composition The residual encoder (724) is configured to generate transform coefficients by encoding the residual data based on the residual data manipulation. composition In the example, a residual encoder (724) is configured to transform the residual data in the frequency domain to generate transform coefficients. composition The transform coefficients are subjected to a quantization process to obtain quantized transform coefficients.

[0082] The entropy encoder (725) formats the bitstream to include the encoded blocks. composition The entropy encoder (725) then encodes the image according to an appropriate standard, such as the HEVC standard, to include various information. composition In an example, the entropy encoder (725) may include general control data, selected prediction information (e.g., intraframe prediction information or interframe prediction information), residual information, and other suitable information in the bitstream. composition Disclosure Object According to the method, in the inter-frame mode or the bidirectional prediction mode, merge There is no residual information when coding a block in a sub-mode.

[0083] 8 shows a diagram of a video decoder (810) according to another embodiment of the present disclosure. The video decoder (810) is configured to receive encoded pictures that are part of an encoded video sequence and to decode the encoded pictures to generate reconstructed pictures. composition In the example, the video decoder (810) is used in place of the video decoder (410) in the example shown in FIG.

[0084] In the example shown in FIG. 8, the video decoder (810) includes an entropy decoder (871), an interframe decoder (880), a residual decoder (873), a reconstruction module (874), and an intraframe decoder (872), all connected together as shown in FIG.

[0085] The entropy decoder (871) constructs the coded picture in response to the coded picture. Syntax Reconstruct the symbols that represent the elements composition Such a symbol may, for example, indicate the mode for coding the block (e.g., intra mode, inter mode, bi-predictive mode, inter mode and bi-predictive mode). merge The intra decoder (872) or inter decoder (880) may include a pre-quantized sub-mode or another sub-mode that recognizes prediction information (e.g., intra or inter prediction information) of the samples or metadata used to make a prediction, such as residual information in the form of quantized transform coefficients, for example, to be used by the intra decoder (872) or inter decoder (880), respectively. In an example, the inter prediction information is provided to the inter decoder (880) if the prediction mode is an inter or bidirectional prediction mode, and the intra prediction information is provided to the intra decoder (872) if the prediction type is an intra prediction type. The residual information may be dequantized and provided to the residual decoder (873).

[0086] The inter-frame decoder (880) is configured to receive the inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information. composition It has been done.

[0087] The intraframe decoder (872) receives the intraframe prediction information and generates a prediction result based on the intraframe prediction information. composition It has been done.

[0088] The residual decoder (873) performs inverse quantization to extract inverse quantized transform coefficients and processes the inverse quantized transform coefficients to transform the residual from the frequency domain to the spatial domain. compositionThe residual decoder (873) may require some control information (to include the quantization parameter QP), which may be provided from the entropy decoder (871) (data path not shown since this is little control information).

[0089] A reconstruction module (874) is arranged to combine the residual output from the residual decoder (873) with a prediction result (output by an inter-frame prediction module or an intra-frame prediction module, as the case may be) in the spatial domain to generate a reconstructed block. composition The reconstructed block may be part of a reconstructed picture, which may be part of a reconstructed video. It should be noted that other suitable operations, such as a deblocking operation, may be performed to improve visual quality.

[0090] It should be noted that the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) may be implemented using any suitable technology. In one embodiment, the video encoders (403), (603), and (703) and the video decoders (410), (510), and (810) may be implemented using one or more integrated circuits. In another embodiment, the video encoders (403), (603), and (603) and the video decoders (410), (510), and (810) may be implemented using one or more processors executing software instructions.

[0091] The following is the disclosure Object Various embodiments of the intraframe prediction method (also called intraframe prediction) according to the present invention will be described.

[0092] In some video compression techniques, intra prediction is performed on samples of a given picture, which are hereafter referred to as a "unit" or block. For samples in a unit, the unit can have any shape. The unit can be contiguous or non-contiguous. In some video compression techniques, the shape of the unit is restricted to a rectangular block of samples. The dimensions of the rectangular block may be positive integers.

[0093] Some video compression techniques limit the size of a rectangular block in each dimension, eg, the X and Y dimensions, to a power of two (eg, 4 samples, 8 samples, 16 samples, . . . ).

[0094] Some video compression techniques restrict the shape of rectangular blocks to be square, i.e., the size in the X and Y dimensions of the rectangular block is equal. In some instances, the size may or may not be a power of two.

[0095] Before describing this disclosure further, the terms "available" and "availability" are introduced below. They take into account the unit of the sample. The samples may be arranged in a square, rectangular or any other suitable shape. Other factors Among them , the encoded bitstream structure including the bitstream divided into spatial locations of units in a picture, slices, tiles, etc. Depending on ,Metadata of a certain predicted sample or other predictive entity (e.g., prediction direction of surrounding units) may or may not be "available" for the prediction of the sample or the prediction of other predictive entities of the unit. In some video coding techniques, the decoding order of the units follows the scan order, i.e., left to right, top to bottom, and thus potential reference information and samples from units following the unit being reconstructed in the decoding order may be "available" for the prediction of the sample or the prediction of other predictive entities of the unit. Naturally Therefore, the prediction data to the right or below the unit being reconstructed is unavailable.

[0096] In some instances, certain predicted samples and other prediction entities may be unavailable even if they are contained in a unit preceding the unit being reconstructed in decoding order and to the left or above the unit being reconstructed. For example, if the unit being reconstructed is a picture or a slice or a (separate) tile, Picture Segment In some cases, a sample or prediction entity may be unavailable if the sample or prediction entity is located at a boundary of a picture. In various examples, slice and tile boundaries are considered picture boundaries for purposes of prediction. Similarly, when encoding a reference unit in a mode that does not allow the generation or use of prediction entities, prediction entities other than prediction samples may be unavailable even if prediction samples are available. For example, a prediction unit encoded in skip mode does not have a prediction direction associated with it.

[0097] When a prediction sample or prediction entity is unavailable, at least in some cases, adjacent samples of the prediction sample are used. R If a prediction sample / prediction entity is predicted, the prediction method of The accuracy may be suboptimal, for example. However, if the encoder selects a prediction mode based on state information including both the predicted sample values ​​and how to generate the predicted sample values ​​(including prediction from samples that are predicted due to unavailability), then in at least some cases the encoder can use a mode that does not rely on intra-frame prediction. In some examples, a rate-distortion optimization technique may be used to select an appropriate mode.

[0098] Both the predicted sample and the available neighboring predicted samples may be, for example, luma samples, chroma samples, samples belonging to a given color plane, etc. For example, in some video processing systems using a video decoder, the video is sampled in a YCrCb 4:2:0 sampling structure, where the chroma samples Cr and Cb are the corresponding chrominance samples. MahiraSince the image is subsampled and processed in planes, intra prediction occurs separately for each color plane in the Y, Cr, and Cb color planes. In some cases, an encoder may generate intra prediction control based on the Y plane, signal the intra prediction control in the encoded video bitstream in relation to the Y plane, and then apply the intra prediction control to the Y plane and the Cr / Cb planes, respectively, at the decoder. In another example, samples are generated using green samples of a picture in RGB color space, and then applied to the corresponding R and B color planes. Red S Sample Blue S In other scenarios, both the encoder and the decoder perform intra prediction for one or more color planes independent of the other color planes. Other suitable sampling configurations, color spaces, etc. may be used for the intra prediction.

[0099] Referring to FIG. 9, in one embodiment, the unit being reconstructed (hereinafter referred to as "block") (901) has a rectangular shape but not a non-square shape, and the block being reconstructed (901) can be referred to as a non-square block (901). In an example, the block (901) includes samples S11-S14 and S21-S24 in a coded picture. In an example, the samples in the block (901) may be predicted using prediction samples in the same coded picture of the block (901) based on intraframe prediction, for example, prediction samples R01-R09 and R10-R70. Intraframe prediction of the samples in the block (901) may be performed along an intraframe prediction direction, also referred to as a prediction direction in the present disclosure.

[0100] In some embodiments, the width of the non-square block (901) is from left to right and the height of the non-square block (901) is from top to bottom, as shown in FIG. 9 for example. Similarly, the first direction (915) points from left to right and the second direction (925) points from top to bottom. The first direction (915) and the second direction (925) form four quadrants: lower left quadrant I, upper left quadrant II, upper right quadrant III, and lower right quadrant IV. The diagonal direction (928) points from upper right to lower left and equally divides lower left quadrant I and upper right quadrant III.

[0101] Typically, for square blocks, the intra prediction direction of the video compression technique can be optimized. With reference to FIG. 9, the second set of intra prediction directions (920) of square blocks includes the intra prediction directions (902-912). The second set of intra prediction directions (920) of square blocks covers a second angle range (924). In some embodiments, the second angle range (924) extends from the first direction (915) 135° clockwise (CW) to 45° counterclockwise (CCW) from the first direction (915), thus covering an angle range of 180°. With reference to FIG. 9, the first extreme prediction direction 902, referred to as the second angle range (924), is 135° clockwise from the first direction (915). The prediction direction 902 is parallel to the diagonal direction (928). The prediction direction 912, referred to as the second end of the second angular range (924), is 45° counterclockwise from the first direction (915). In various implementations, the second set (920) can include other prediction directions not shown in FIG. 9. In general, the second set of intra prediction directions (920) may include, for example, any suitable intra prediction directions between the first end (902) and the second end (912). For example, HEVC uses 65 intra prediction directions.

[0102] An intra prediction direction that may be useful for square blocks may not be useful for non-square blocks, such as block (901), because some samples of block (901) have low spatial correlation with the prediction samples used for some intra prediction directions. For example, when intra prediction direction (902) is used for intra prediction, samples S11 and S21 in block (901) may be predicted according to reference samples R20 and R30 that are direct neighbors of block (901). Some samples of block (901) are predicted according to reference samples that are not direct neighbors but are relatively (spatially) far from block (901). For example, sample S24 is predicted according to reference sample R60 that is spatially far. In various embodiments, intra prediction works well with a close spatial relationship between the reference sample and the sample to be predicted, for example, the sample to be predicted is spatially close to the reference sample. Thus, in various embodiments, for a non-square block (901), a rate-distortion optimized encoder may not select an intra prediction direction, for example, of the intra prediction direction (902).

[0103] In some embodiments, the intra prediction direction is mapped to an intra prediction mode (also called a prediction mode), which may also be mapped to a codeword. As mentioned above, statistically, some intra prediction directions are more likely to be used than other intra prediction directions. The certain intra prediction direction may be mapped to a first codeword, and the other intra prediction direction may be mapped to a second codeword. Thus, the first codeword may use fewer bits than the second codeword, and thus is shorter than the second codeword. In some examples, the intra prediction direction / mode mapped to the first codeword is referred to as a "short" mode. The "short" mode may be a mode that is more likely to be selected by a rate-distortion optimized encoder. For example, for a square block, the intra prediction direction (902) may correspond to a short mode.

[0104] If the same mapping from intra prediction direction to intra prediction mode designed and optimized for square blocks is used, for example, the valuable "short" mode of the intra prediction direction used for square blocks may be wasted for the intra prediction direction used for non-square blocks (901) in the intra prediction direction (902). As mentioned above, if there is a direct mapping between intra prediction modes and variable length codewords, the "short" mode can be represented by a short variable length codeword.

[0105] In the same or another embodiment, an intra prediction direction located at an edge, e.g., at the first edge (902), of the second set of intra prediction directions (920) used for square blocks is less likely to be selected by the rate-distortion optimized encoder for the non-square block (901) because there is low spatial correlation between a sample in the non-square block (901) and a corresponding reference sample used based on the intra prediction direction located at the edge, and therefore the intra prediction direction is not used in the first set of intra prediction directions for the non-square block (901). For example, for a certain block shape, e.g., a non-square block (901) (see also the following description), the prediction directions between a first edge (902) and an intra prediction direction (904) that is 22.5° CW from the first edge (902) can form a sub-range (922) of a second angle range (924), and the sub-range (922) includes intra prediction directions that are not used in the first set of intra prediction directions for the non-square block (901). The sub-range (922) is also referred to as a deleted sub-range (922). In one example, the sub-range (922) does not include the intra prediction direction (904) but includes the first edge (902) and any intra prediction directions in the second set (920) between the first edge (902) and the intra prediction direction (904), e.g., the intra prediction direction (903). Referring to FIG. 9, a first set of intra-prediction directions for a non-square block (901) covers a first angle range (926) having two extreme, intra-prediction directions (904 and 912).

[0106] In the same or another embodiment, the subrange (922) that includes intra-frame prediction directions that are not used in the first set of intra-frame prediction directions of the non-square block (901) is )of The spatial characteristics of the block (901) may depend on the spatial characteristics. In the same or another embodiment, the spatial characteristics of the block (901) may include the shape of the block (901). In some examples, the shape of the block (901) may be the relationship of the size in the X dimension and the Y dimension of the block (901), the size in the X dimension of the block (901), i.e., the first size in the X dimension, width from left to right, and the size in the Y dimension of the block (901), i.e., the second size in the Y dimension, height from top to bottom. By way of example, in the same or another embodiment, for a block (901) having an aspect ratio of 2:1 between the first size in the X dimension and the second size in the Y dimension, as shown in FIG. 9, the subrange (922) may be between the intra prediction direction (902) (which is 135° CW from the first direction (915)) and the intra prediction direction (904) (which is 22.5° CW from the intra prediction direction (902)) in the lower left quadrant I.

[0107] For aspect ratios greater than 1, the subrange (922) may include the first edge (902) of the second set (920) and be located in the lower-left quadrant I. For aspect ratios greater than 1, the subrange (922) may be larger and therefore include more of the intra-frame prediction directions of the second set (920).

[0108] Generally, the sub-range is determined based on symmetry along a diagonal direction (928), and the sub-range includes intra-frame prediction directions for a second set of square blocks that are not used in the intra-frame prediction directions of a first set of non-square blocks.

[0109] In some embodiments, when the aspect ratio of the non-square block being reconstructed is less than 1, the subrange in the second set (920) includes the second edge (912) of the second set (920) and is located in the upper right quadrant III. Note that the subrange in the second set (920) is not included in the intra prediction direction of the first set of non-square blocks. In the same or another embodiment, for a non-square block with an aspect ratio of 1:2 between its first size in the X dimension and its second size in the Y dimension, the subrange may be between the second edge (912) and the intra prediction direction (911) in the upper right quadrant III. In various embodiments, the subrange includes the second edge (912). The second edge (912) is opposite the diagonal direction 928, and the intra prediction direction (911) is 22.5° CCW from the second edge (912). As the aspect ratio decreases from being less than 1, the subrange may become larger and therefore include more intra-prediction directions in the second set (920).

[0110] Referring to FIG. 10, a non-square block or block (1001) of 1×4 samples is shown, which indicates a block size having an aspect ratio of 1:4. Similarly, a second set of intra prediction directions (920) of square blocks includes intra prediction directions (902-912), as shown in the lower right of FIG. 10. In each example, the second set of intra prediction directions (920) of square blocks and the second angle range (924) are the same as the second set of intra prediction directions and the second angle range shown in FIG. 9, and therefore detailed descriptions are omitted for clarity. The four quadrants I-IV are also the same as the four quadrants of FIG. 9, and therefore detailed descriptions are omitted for clarity.

[0111] In various embodiments, a first set of intra prediction directions may be used for non-square blocks (1001), and the first set does not include intra prediction directions in a sub-range (1022) of a second angular range (924). As shown in FIG. 10, the sub-range (1022) may be between a second end (912) and the intra prediction direction (910). The second end (912) is opposite the diagonal direction 928 or 45° CCW from the first direction (915), and the intra prediction direction (910) is 11.25° CW from the intra prediction direction (909) opposite the second direction (925). In various embodiments, the sub-range (1022) includes the second end (912) and does not include the intra prediction direction (910). Referring to FIG. 10, the first set covers a first angular range (1026). In the example, the first angle range (1026) includes the first end (902) of the second set (920), the intra prediction direction (910), and other intra prediction directions of the second set (920) between the first end (902) and the intra prediction direction (910).

[0112] Other suitable subranges for use with non-square blocks of other block shapes and / or other aspect ratios may include one or more intra-frame prediction directions in a second set of square blocks (920) that are not used for the first set of non-square blocks.

[0113] In the same or another embodiment, the intra prediction modes of the square blocks corresponding to the intra prediction directions that are part of the subrange of the deletion are not used for the non-square blocks. As an example, in FIG. 9, the intra prediction modes associated with the intra prediction directions (903) that are part of the subrange (922) are not used for the non-square blocks (901). In some embodiments, the table of modes associates the intra prediction directions with the corresponding intra prediction modes of the blocks. The table of modes of the non-square blocks (901) can be shortened accordingly, allowing for optimized entropy coding and better coding efficiency since fewer intra prediction modes are used. In the same or another embodiment, the table of modes can be newly sorted according to the possibilities of the intra prediction directions still represented in the table of modes.

[0114] In the same or another embodiment, if an intra prediction direction in the deleted sub-range is not used for a non-square block, the associated intra prediction mode may be newly allocated and used for other purposes, including signaling a previously unused direction, a mode not directly related to a prediction direction, filter control of a filter related to a reference sample or a sample of intra prediction, etc.

[0115] In the same or another embodiment, an intra prediction direction, called the additional intra prediction direction, is added to the first set of intra prediction directions used for the non-square block. The number of the additional intra prediction directions may be the same as the number of intra prediction directions in the deleted sub-range (called the deleted intra prediction directions). The additional intra prediction directions may include a sub-range, called the additional sub-range. The additional sub-range is included in the first angular range covered by the first set of intra prediction directions for the non-square block. The additional sub-range may have the same geometric structure as the deleted sub-range, as follows:

[0116] FIG. 11 illustrates a non-square block (1101) of a 4×2 block being reconstructed, having the same aspect ratio as the non-square block (901) illustrated in FIG. 9. Also illustrated is a second set of intra prediction directions (920) of square blocks. In each example, the second set of intra prediction directions (920) and the second angle range (924) of square blocks are the same as the second set of intra prediction directions and the second angle range illustrated in FIG. 9, and therefore detailed descriptions are omitted for clarity. Although the intra prediction directions 902-912 of square blocks are illustrated, only the intra prediction directions 902-904, 911-912 are illustrated in FIG. 11 for clarity. The four quadrants I-IV are the same as the four quadrants in FIG. 9, and therefore detailed descriptions are omitted for clarity.

[0117] Similarly, the intra prediction directions in the deleted subrange or subrange (922) are not included in the first set of intra prediction directions of the non-square block (1101). The subrange (922) is the same as the subrange shown in FIG. 9, and therefore a detailed description is omitted for clarity. Dashed lines are used to depict the two intra prediction directions (902, 903) in the subrange (922). In this example, again, the intra prediction mode representing the intra prediction directions (902, 903) of the square block can be used to represent two additional intra prediction directions (1106, 1107) in the additional subrange (1108). Thus, the first set of intra prediction directions of the non-square block (1101) covers a first angle range (1126) having a first end (904) and a second end (1107). The first end or intra prediction direction (904) is 22.5° CW from the diagonal direction (928), and the second end (1107) is 22.5° CW from the intra prediction direction (912) opposite the diagonal direction (928). The first angle range (1126) includes the additional sub-range (1108) and does not include the deleted sub-range (922). For example, in some examples shown in FIG. 11, the deleted sub-range (922) includes intra prediction directions between the intra prediction direction (902) and the intra prediction direction (904). Also, the deleted sub-range (922) includes the intra prediction direction (902) and does not include the intra prediction direction (904). Meanwhile, the additional sub-range (1108) includes intra prediction directions between the second end (912) of the second set (920) and the additional intra prediction direction (1107). Additionally, the additional subrange (1108) includes an additional intra-frame prediction direction (1107) and does not include the second end (912).

[0118] 11, the deletion subrange (922) and the additional subrange (1108) are symmetrical about the diagonal direction (928). As described above, the deletion subrange (922) covers an angular range of 22.5° CW from the diagonal direction (928), and the additional subrange (1108) covers an angular range of 22.5° CW from the opposite direction of the diagonal direction (928).

[0119] An additional intra prediction direction may be beneficially applied to the non-square block (1101) shown in FIG. 11. For example, consider an additional intra prediction direction (1107). The intra prediction direction (1107) may be used to predict sample S11 in the non-square block (1101) according to reference sample R03, and to predict sample S14 according to reference sample R06 adjacent to direct neighbor R05 of the non-square block (1101). Thus, the additional intra prediction direction (1107) predicts samples included in the block (1101), and the reference samples for predicting samples in the block (1101) are relatively close to the samples in the block (1101) compared to using the intra prediction direction in the deletion subrange (922).

[0120] Without increasing the number of intra-frame prediction modes for non-square blocks (1101) compared to the number of intra-frame prediction modes for square blocks. addition In some embodiments, the number of intra prediction directions in the removed subrange (922) is the same as the number of intra prediction directions in the added subrange (1108), so that the number of intra prediction directions in the first set of non-square blocks (1101) is the same as the number of intra prediction directions in the second set of square blocks (920). In some embodiments, as described above, the intra prediction modes assigned to the intra prediction directions in the removed subrange (922) of square blocks are newly assigned to the intra prediction directions in the added subrange (1108) of non-square blocks, so that the number of intra prediction modes used for the first set of non-square blocks (1101) is equal to the number of intra prediction modes used for the second set of square blocks (920).

[0121] In some examples, the number of intra prediction directions in the first set of non-square blocks (1101) may be less than the number of intra prediction directions in the second set of square blocks (920) when the number of intra prediction directions in the additional subrange is less than the number of intra prediction directions in the deleted subrange. In some other examples, such as those shown in Figure 9, the number of intra prediction directions in the first set may be less than the number of intra prediction directions in the second set when the first set does not include the additional subrange. Thus, the number of intra prediction modes of the non-square blocks (1101) is less than the number of intra prediction modes of the square blocks.

[0122] In some examples, to predict samples (S21-S24) in the second row of the non-square block (1101) using intra prediction directions (1106) or (1107), an interpolation / filtering technique can be preferably used to predict samples (S21-S24) according to more than one reference sample or to avoid aliasing artifacts. Such an interpolation / filtering technique includes a technique for specifying an intra prediction direction that is not a multiple of 45° from the diagonal direction (928), for example, as specified in H.265. For example, the additional intra prediction directions (1106 and 1107) are 11.25° CW and 22.5° CW from the opposite direction of the diagonal direction (928), and therefore are not a multiple of 45° from the diagonal direction (928). On the other hand, the intra-frame prediction direction 907 is 90° CW from the diagonal direction (928), and is therefore a multiple (2x) of 45° from the diagonal direction (928).

[0123] The symmetry considerations discussed above in the context of removing intra prediction directions for removal can be applied to adding additional intra prediction directions as well. Similarly, the size of the additional subrange can depend on the block shape of the block (1101), similar to how the size of the subrange for removal depends on the block size. As discussed above with reference to FIG. 9, an increase in the aspect ratio of the non-square block (901) greater than 1 results in a larger subrange (922), and therefore the second set (920) includes more intra prediction directions.

[0124] FIG. 12 is a flow chart outlining a process (1200) according to an embodiment of the present disclosure. The process (1200) is used for intraframe prediction to generate a prediction block for a non-square block being reconstructed. In various embodiments, the process (1200) is performed, for example, by a processing circuit in the terminal device (310, 320, 330, and 340), a processing circuit performing the function of a video encoder (403), a processing circuit performing the function of a video decoder (410), a processing circuit performing the function of a video decoder (510), a processing circuit performing the function of an intraframe prediction module (552), a processing circuit performing the function of a video encoder (603), a processing circuit performing the function of a predictor (635), a processing circuit performing the function of a decoder (633), a processing circuit performing the function of an intraframe encoder (722), a processing circuit performing the function of an intraframe decoder (872), etc. The process starts at (S1201) and proceeds to (S1210).

[0125] In step S1210, a block size of the non-square block being reconstructed is obtained. For example, at least one Syntax Decrypt the at least one element. SyntaxThe element indicates a block size of the non-square block. The block size includes a first size in a first dimension, e.g., a width of the non-square block, and a second size in a second dimension, e.g., a height of the non-square block, and the first size is different from the second size. In some examples, for example, to obtain additional information of the location of the non-square block within the picture being reconstructed.

[0126] At (S1220), the processing circuitry determines an intra prediction mode for the non-square block. In various embodiments, the intra prediction mode corresponds to an intra prediction direction in the first set of intra prediction directions for the non-square block. As described above with reference to Figures 9 to 11, the first set of intra prediction directions does not include one or more intra prediction directions in the second set of intra prediction directions for the square block.

[0127] At (S1230), the processing circuit selects a reference sample for the sample in the non-square block based on an intra prediction mode. With reference to FIG. 11, in some examples, the non-square block is block (901) and the intra prediction mode indicates an intra prediction direction (912). For example, to predict sample S21 using the intra prediction direction (912), the processing circuit determines that the reference sample is R03.

[0128] In (S1240), as described above, the processing circuitry determines whether the reference sample is available. If the reference sample is available, the process (1200) proceeds to (S1260). If the reference sample is not available, the process (1200) proceeds to (S1250).

[0129] In (S1250), as described above, the processing circuit determines the value of the reference sample, for example, by using adjacent samples of the reference sample. For example, when the reference sample R03 is unavailable, the value of the reference sample R03 may be determined by using other samples, such as R02. Next, the process (1200) proceeds to (S1260).

[0130] At (S1260), the processing circuit predicts samples in the non-square block based on the reference samples. In some embodiments, the value of sample S21 is obtained based on the value of reference sample R03. For example, the value of sample S21 is equal to the value of reference sample R03. In some examples, when the intra prediction mode indicates, for example, an intra prediction direction (911), the value of sample S21 may be determined based on more than one reference sample using interpolation, filtering, etc. Then, the process proceeds to (S1299) and ends.

[0131] The process (1200) may be adjusted appropriately. For example, at (S1230), if the intra prediction mode indicates, for example, an intra prediction direction (910), the processing circuitry may select more than one reference sample for the samples in the non-square block based on the intra prediction mode.

[0132] The techniques may be implemented as computer software by computer readable instructions and physically stored on one or more computer readable media. For example, FIG. Object 13 illustrates a computer system (1300) for implementing some embodiments of the present invention.

[0133] Computer software may be encoded in any suitable machine code or computer language, which may be edited, compiled, linked, or otherwise constructed to produce code containing instructions that are executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), or the like, or may be executed by interpretation, microcode execution, or the like.

[0134] The instructions may be transmitted to any type of computer or Components The present invention can be implemented on a variety of devices, including personal computers, tablets, servers, smartphones, gaming devices, Internet of Things devices, etc.

[0135] The computer system (1300) shown in FIG. Components The examples are exemplary in nature and are not limiting as to the scope or functionality of the use of the example computer software for implementing the present disclosure. Components The arrangement of the computer system (1300) is also shown in the exemplary embodiment. Components Any of the Components Nor should the subject matter be construed as having any dependency or requirement regarding the various embodiments or combinations thereof.

[0136] The computer system (1300) may include several human machine interface input devices. Such human machine interface input devices may include one or more People The human-machine interface device can respond to inputs from a user, for example, tactile inputs (e.g., keystrokes, slides, data glove movements), audio inputs (e.g., voice, tapping), visual inputs (e.g., posture), and olfactory inputs (not shown). The human-machine interface device can also capture certain media that are not necessarily directly related to human conscious inputs, such as audio (e.g., voice, music, ambient sounds), images (e.g., scanned images, photographic images obtained from still image capture devices), and videos (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0137] The input man-machine interface devices may include one or more of a keyboard (1301), a mouse (1302), a touchpad (1303), a touch panel (1310), a data glove (not shown), a joystick (1305), a microphone (1306), a scanner (1307), and an image capture device (1308) (only one of each listed).

[0138] The computer system (1300) may further include human-machine interface output devices. Such human-machine interface output devices may stimulate one or more of the senses of the human user, for example, through haptic output, sound, light, and smell / taste. Such human-machine interface output devices may include haptic output devices (e.g., haptic feedback via a touch panel (1310), data gloves (not shown), or joystick (1305), although there are also haptic feedback devices that are not used as input devices), audio output devices (e.g., speakers (1309), headphones (not shown)), visual output devices (e.g., a screen (1310), including a CRT screen, LCD screen, plasma screen, OLED screen, each of which may or may not have touch panel input and haptic feedback capabilities, some of which may provide two-dimensional visual output or three or more dimensional output, such as by means of stereoscopic image output, including virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown).

[0139] The computer system (1300) may further include human-accessible storage devices and associated media, such as optical media including CD / DVD ROM / RW (1320) with media such as CD / DVD (1321), thumb drives (1322), removable hard drives or solid state drives (1323), magnetic tapes and floppy disks (not shown). Conventional magnetic media, dedicated ROM / ASIC / PLD based devices, such as dongles (not shown), etc.

[0140] Those skilled in the art will appreciate that the present disclosure Object In conjunction with the above, it should be understood that the term "computer-readable medium" as used does not include transmission media, carrier waves or other transient signals.

[0141] The computer system (1300) may further include interfaces for one or more communication networks. The networks may be, for example, wireless, wired, or optical. local The network may be a wide area, urban, vehicular, industrial, real-time, delay tolerant network, etc. Examples of networks include local area networks such as Ethernet, cellular networks including wireless LAN, GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial television, vehicular and industrial networks including CANBus, etc. Some networks typically require an external network interface adapter coupled to some general purpose data port or peripheral bus (1349) (e.g., a USB port of the computer system (1300)), while other networks are typically integrated into the core of the computer system (1300) by coupling to a system bus described below (e.g., an Ethernet interface to a PC computer system, or a cellular network interface to a smartphone computer system). Through any of these networks, the computer system (1300) can communicate with other entities. Such communications may be one-way and receive only (e.g., broadcast television), one-way and transmit only (e.g., a CANbus to a CANbus device), or two-way (e.g., over a local or wide area digital network to another computer system). Specific protocols and protocol stacks may be utilized for each of these networks and network interfaces described above.

[0142] The man-machine interface devices, human-accessible storage devices and network interfaces may be coupled to a core (1340) of the computer system (1300).

[0143] The core (1340) includes one or more central processing units (CPU) (1341), graphics processing units (GPU) (1342), specialized programmable processing units in the form of field programmable gate arrays (FPGA) (1343), hardware accelerators for certain tasks (1344), etc. These devices are connected via a system bus (1348), along with read only memory (ROM) (1345), random access memory (1346), internal mass storage devices (1347) such as hard disk drives, SSDs, etc. that are not accessible to the internal user. In some computer systems, the system bus (1348) can be expanded by additional CPUs, GPUs, etc., by accessing the system bus (1348) in the form of one or more physical plugs. Peripheral devices are coupled to the core's system bus (1348) directly or through a peripheral bus (1349). Peripheral bus architectures include PCI, USB, etc.

[0144] The CPU (1341), GPU (1342), FPGA (1343) and accelerator (1344) can execute a number of instructions, which, when combined, constitute the computer code referred to above. The computer code is stored in ROM (1345) or RAM (1346). Transient data is stored in RAM (1346) and permanent data may be stored, for example, in an internal mass storage device (1347). A cache memory can be used to quickly store and retrieve any of the memory devices, and the cache memory can be closely associated with one or more of the CPU (1341), GPU (1342), mass storage device (1347), ROM (1345), RAM (1346), etc.

[0145] The computer readable medium bears computer code for performing various computer implemented operations, and may be media and computer code specially designed and constructed for the purposes of this disclosure, or may be of the type known and available to those skilled in the art of computer software.

[0146] By way of example and not limitation, a computer system having the architecture (1300), and in particular the core (1340), can provide functionality by having a processor(s) (including CPU, GPU, FPGA, accelerator, etc.) execute software embodied in one or more tangible computer-readable media. Such computer-readable media may be storage devices such as the user-accessible mass storage media discussed above, and non-transitory core (1340) internal mass storage (1347) or ROM (1345). Software for implementing the present disclosure in various embodiments may be stored in such devices and executed by the core (1340). Depending on the particular needs, the computer-readable media may include one or more storage devices or chips. The software may cause the core (1340), and in particular the processors therein (including CPU, GPU, FPGA, etc.) to execute certain processes or parts of certain processes described herein, to define data structures stored in RAM (1346), and to modify such data structures based on the processes defined by the software. Also, or alternatively, the computer system may provide functionality embodied in circuitry (e.g., accelerator (1344)), either hardwired or otherwise, that can operate in place of or in conjunction with software to perform particular processes or portions of particular processes described herein. Where appropriate, references to software may include logic, and conversely, references to logic may include software. Where appropriate, references to computer-readable media may include circuitry (e.g., integrated circuits (ICs)) on which software is stored for execution, circuitry embodying logic for execution, or both. The present disclosure includes any appropriate combination of hardware and software. Appendix A: Acronyms MV: Motion Vector HEVC: High Efficiency Video Coding SEI: Auxiliary Expansioninformation VUI: Video usability information GOP: Group of Pictures TU: conversion unit PU: Prediction unit CTU: Coding Tree Unit CTB: coding tree block PB: Predicted block HRD: virtuality Reference Decoder SNR: Signal to Noise Ratio CPU: Central Processing Unit GPU: Graphics Processing Unit CRT: cathode ray tube LCD: Liquid crystal display OLED: Organic Light Emitting Diode CD:Compact Disc DVD: Digital Video Disc ROM: Read-Only Memory RAM: Random Access Memory ASIC: Application Specific Integrated Circuit PLD: Programmable Logic Device LAN: Local Area Network GSM: Global System for Mobile Communications LTE: Long Term Evolution CANBus: Controller Area Network Bus USB: Universal Serial Bus PCI: Peripheral Component Interconnect FPGA: Field Programmable Gate Area SSD: Solid State Drive IC: Integrated Circuit CU: Coding Unit JEM: Joint Exploration Model VVC: General Purpose Video Coding BMS: Benchmark Set CU: Coding Unit

[0147] Although the present disclosure describes some illustrative embodiments, there are modifications, substitutions, and various substitute equivalents which fall within the scope of the present disclosure. Thus, although not expressly set forth herein, there are other modifications, substitutions, and equivalents which embody the principles of the present disclosure and are within the spirit and scope of the present disclosure. Many The systems and methods will occur to those skilled in the art.

Claims

1. 1. A method for transmitting a video bitstream encoded by an encoder, comprising: obtaining a video bitstream including pictures of non-square blocks having a rectangular shape; obtaining at least one syntax element indicating a block size of the non-square block; transmitting the video bitstream including the at least one syntax element; Including, the block size comprises a first size in a first dimension and a second size in a second dimension, the first size being different from the second size; the first set of intra prediction directions for the non-square block are determined from the second set of intra prediction directions for square blocks, the first set of intra prediction directions including a first angular sub-range of the second set of intra prediction directions, excluding a second angular sub-range of the second set of intra prediction directions that is in a predetermined range from a lower left diagonal of the square block if the height of the non-square block is smaller than its width, and excluding a third angular sub-range of the second set of intra prediction directions that is in a predetermined range from a upper right diagonal of the square block if the height of the non-square block is greater than its width; The method, wherein samples of the non-square block are predicted based on the first set of intra-frame prediction directions of the non-square block.

2. The method of claim 1 , wherein the first set of intra-frame prediction directions includes a fourth angular sub-range that is within a predetermined range from a top right diagonal or a bottom left diagonal of the square block.

3. 3. The method of claim 1, wherein the first set of intra prediction directions does not include one intra prediction direction in the second set of intra prediction directions that corresponds to one end of the angular range covered by the second set of intra prediction directions.

4. The method of claim 3 , wherein an intra prediction mode used for the first set of intra prediction directions does not include an intra prediction mode used for the one intra prediction direction in the second set of intra prediction directions.

5. 5. The method of claim 3 or 4, wherein an intra prediction mode used for the one intra prediction direction in the second set of intra prediction directions is assigned to an intra prediction direction in the first set of intra prediction directions.

6. 6. The method of claim 5, wherein in a combined angular range covered by the first set of intra prediction directions and the second or third angular sub-range, the one intra prediction direction in the first set of intra prediction directions corresponds to a first end of the combined angular range, and the second or third angular sub-range includes a second end of the combined angular range, the second end being one end of the combined angular range covered by the second set of intra prediction directions.

7. another angular range is covered by the first set of intra-frame prediction directions; The method of claim 5 , wherein the one intra prediction direction in the first set of intra prediction directions is outside the other angle range covered by the second set of intra prediction directions.

8. 8. A method according to claim 5, wherein the number of intra-frame prediction directions in the first set that are not included in the second set of intra-frame prediction directions is equal to the number of intra-frame prediction directions in the second set that are not included in the first set of intra-frame prediction directions.

9. The method of claim 1 , wherein the second angular sub-range of the second set of intra prediction directions is determined based on a shape or aspect ratio of the non-square block.

10. The method of claim 1 , wherein the third angular sub-range of the second set of intra prediction directions is determined based on a shape or an aspect ratio of the non-square block.

11. 1. An apparatus including a processing circuit and a memory, Apparatus, wherein the processing circuitry is configured to perform the method of any one of claims 1 to 10 by executing a program stored in the memory.

12. A computer program product causing at least one processor to carry out the method according to any one of claims 1 to 10.

13. A method for processing visual media data, comprising: obtaining a visual media file; Including, performing a conversion between the visual media file and a video bitstream containing pictures of non-square blocks having rectangular shapes; Including, the video bitstream includes at least one syntax element that indicates a block size of the non-square block; the block size comprises a first size in a first dimension and a second size in a second dimension, the first size being different from the second size; the first set of intra prediction directions for the non-square block are determined from the second set of intra prediction directions for square blocks, the first set of intra prediction directions including a first angular sub-range of the second set of intra prediction directions, excluding a second angular sub-range of the second set of intra prediction directions that is in a predetermined range from a lower left diagonal of the square block if the height of the non-square block is smaller than its width, and excluding a third angular sub-range of the second set of intra prediction directions that is in a predetermined range from a upper right diagonal of the square block if the height of the non-square block is greater than its width; The method, wherein samples of the non-square block are predicted based on the first set of intra-frame prediction directions of the non-square block.

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