METHOD AND APPARATUS OF POSITION DEPENDENT PREDICTION COMBINATION FOR OBLIQUE DIRECTIONAL INTRA PREDICTION

A method for an intra predicting process of a video block is provided. The method comprises: obtaining a predicted sample value for a sample of the current coding block; obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and weighting the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and outputting the modified predicted sample.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of picture processing and more particularly to shape-adaptive resampling of residual block for still image and video coding.

BACKGROUND

Video coding (video encoding and decoding) is used in a wide range of digital video applications, for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications.

SUMMARY

Embodiments of the present disclosure provide apparatuses and methods for encoding and decoding according to the independent claims.

The present disclosure discloses: A method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: obtaining a predicted sample value for a sample of the current coding block; obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; determining a first weight based on the scaling factor value;

determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value and outputting the modified predicted sample value.

In the method as described above, the height of the current coding block may be equal to a value of a difference refH−nTbH, wherein the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block.

In the method as described above, the width of the current coding block may be equal to a value of a difference refW−nTbW, wherein the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block.

The present disclosure further discloses a method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: obtaining a predicted sample value for a sample of the current coding block; obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; wherein, when the scaling factor value is greater than or equal to 0, performing the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value;

calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and outputting the modified predicted sample value.

The method as described above may further comprise: when the scaling factor value is less than 0, outputting the predicted sample value.

The present disclosure further discloses a method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: obtaining a predicted sample value for a sample of the current coding block; obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; wherein, when the intra prediction mode for the current coding block is angular mode, and when the scaling factor value is less than 0, outputting the predicted sample value; otherwise performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value; and outputting the modified predicted sample value.

In the method as described above the height of the current coding block may be equal to a value of a difference refH−nTbH, wherein the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block.

In the method as described above, the width of the current coding block may be equal to a value of a difference refW−nTbW, wherein the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block.

The present disclosure further discloses an encoder comprising processing circuitry for carrying out the method embodiments as described above.

The present disclosure further discloses a decoder comprising processing circuitry for carrying out the method embodiments as disclosed above.

The present disclosure further discloses a computer program product comprising program code for performing the method as described above when executed on a computer or a processor.

The present disclosure further discloses a decoder, comprising: one or more processors; and a non-transitory computer-readable storage medium coupled to the one or more processors and storing programming for execution by the one or more processors, wherein the programming, when executed by the one or more processors, causes the decoder to carry out any one of the preceding method embodiments.

The present disclosure further discloses an encoder, comprising: one or more processors; and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out any one of the preceding method embodiments.

The present disclosure further discloses a non-transitory computer-readable medium carrying a program code which, when executed by a computer device, causes the computer device to perform any one of the preceding method embodiments.

The present disclosure further discloses a decoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first determining unit configured to determine a first weight based on the scaling factor value; a second determining unit configured to determine a second weight based on the scaling factor value; a calculating unit configured to calculate an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; a third obtaining unit configured to obtain a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit configured to output the modified predicted sample value.

The present disclosure further discloses an encoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first determining unit configured to determine a first weight based on the scaling factor value; a second determining unit configured to determine a second weight based on the scaling factor value; a calculating unit configured to calculate an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; a third obtaining unit configured to obtain a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit configured to output the modified predicted sample value.

The present disclosure further discloses a decoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a processing unit, wherein, when the scaling factor value is greater than or equal to 0, the processing unit is configured to perform the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit configured to output the modified predicted sample value.

The decoder as described above may further comprise a second outputting unit wherein the second outputting unit is configured to output the predicted sample value in case the scaling factor value is less than 0.

The present disclosure further discloses an encoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a processing unit, wherein, when the scaling factor value is greater than or equal to 0, the processing unit is configured to perform the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit configured to output the modified predicted sample value.

The encoder as described above may further comprise a second outputting unit wherein the second outputting unit is configured to output the predicted sample value in case the scaling factor value is less than 0.

The present disclosure further discloses a decoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first outputting unit, the first outputting unit being configured to output the predicted sample in case the intra prediction mode for the current coding block is angular mode, and the scaling factor value is less than 0; and otherwise a processing unit configured to performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value; and a second outputting unit configured to output the modified predicted sample value.

The present disclosure further discloses an encoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first outputting unit, the first outputting unit being configured to output the predicted sample in case the intra prediction mode for the current coding block is angular mode, and the scaling factor value is less than 0; and otherwise a processing unit configured to performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value; and a second outputting unit configured to output the modified predicted sample value.

The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

Particular embodiments are outlined in the attached independent claims, with other embodiments in the dependent claims.

According to a first aspect, an example embodiment of the invention relates to a method for intra predicting process of a video (or picture, frame) block, the method comprising: obtaining a predicted sample value for a sample of the block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode); obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block(in an example, both of the height and the width are used to obtain the scaling factor); determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value (in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value) (in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

In an example embodiment, the height of the current coding block is equal to a value of refH−nTbH, the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block.

In a possible implementation form, wherein the width of the current coding block is equal to a value of refW−nTbW, the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block.

According to a second aspect, an embodiment of the invention relates to a method for intra predicting process of a video (or picture, frame) block, the method comprising: obtaining a predicted sample value for a sample of the block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode); obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block(in an example, both of the height and the width are used to obtain the scaling factor); when the scaling factor value is greater than or equal to 0, performing the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value(in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value) (in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

In an example embodiment, the method further comprises: when the scaling factor value is less than 0, output the predicted sample value.

According to a third aspect, an embodiment of the invention relates to a method for intra predicting process of a video (or picture, frame) block, the method comprising:

obtaining a predicted sample value for a sample of the block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode); obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block(in an example, both of the height and the width are used to obtain the scaling factor); when the intra prediction mode for the current coding block is angular mode (but the intra prediction mode for the current coding block is not a horizontal mode and is not a vertical mode), and when the scaling factor value is less than 0, output the predicted sample value; otherwise (the intra prediction mode for the current coding block is not angular mode, or the intra prediction mode for the current coding block is a horizontal mode, or the intra prediction mode for the current coding block is a vertical mode, or the scaling factor value is greater than or equal to 0), performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value(in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value)(in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

In an example embodiment, the height of the current coding block is equal to a value of refH−nTbH, the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block.

In a possible implementation form, wherein the width of the current coding block is equal to a value of refW−nTbW, the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block.

According to a fourth aspect, an embodiment of the invention relates to an encoder (20), which comprising processing circuitry for carrying out the method according to method embodiments.

According to a fifth aspect, an embodiment of the invention relates to a decoder (30), which comprising processing circuitry for carrying out the above described method embodiments.

According to a sixth aspect, an embodiment of the invention relates to a computer program product comprising program code for performing the method according to any one of the preceding embodiments when executed on a computer or a processor.

According to a seventh aspect, an embodiment of the invention relates to a decoder, comprising: one or more processors; and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the decoder to carry out any one of the preceding method embodiments.

According to an eighth aspect, an embodiment of the invention relates to an encoder, comprising: one or more processors; and a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out any one of the preceding methods embodiments.

According to a ninth aspect, an embodiment of the invention relates to a non-transitory computer-readable medium carrying a program code which, when executed by a computer device, causes the computer device to perform any one of the preceding methods embodiments.

In the following identical reference signs refer to identical or at least functionally equivalent features if not explicitly specified otherwise.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the invention or specific aspects in which embodiments of the present invention may be used. It is understood that embodiments of the invention may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

For instance, it is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.

Video coding typically refers to the processing of a sequence of pictures, which form the video or video sequence. Instead of the term “picture”, the term “frame” or “image” may be used as synonyms in the field of video coding. Video coding (or coding in general) comprises two parts video encoding and video decoding. Video encoding is performed at the source side, typically comprising processing (e.g. by compression) the original video pictures to reduce the amount of data required for representing the video pictures (for more efficient storage and/or transmission). Video decoding is performed at the destination side and typically comprises the inverse processing compared to the encoder to reconstruct the video pictures. Embodiments referring to “coding” of video pictures (or pictures in general) shall be understood to relate to “encoding” or “decoding” of video pictures or respective video sequences. The combination of the encoding part and the decoding part is also referred to as CODEC (Coding and Decoding).

In case of lossless video coding, the original video pictures can be reconstructed, i.e. the reconstructed video pictures have the same quality as the original video pictures (assuming no transmission loss or other data loss during storage or transmission). In case of lossy video coding, further compression, e.g. by quantization, is performed, to reduce the amount of data representing the video pictures, which cannot be completely reconstructed at the decoder, i.e. the quality of the reconstructed video pictures is lower or worse compared to the quality of the original video pictures.

Several video coding standards belong to the group of “lossy hybrid video codecs” (i.e. combine spatial and temporal prediction in the sample domain and 2D transform coding for applying quantization in the transform domain). Each picture of a video sequence is typically partitioned into a set of non-overlapping blocks and the coding is typically performed on a block level. In other words, at the encoder the video is typically processed, i.e. encoded, on a block (video block) level, e.g. by using spatial (intra picture) prediction and/or temporal (inter picture) prediction to generate a prediction block, subtracting the prediction block from the current block (block currently processed/to be processed) to obtain a residual block, transforming the residual block and quantizing the residual block in the transform domain to reduce the amount of data to be transmitted (compression), whereas at the decoder the inverse processing compared to the encoder is applied to the encoded or compressed block to reconstruct the current block for representation. Furthermore, the encoder duplicates the decoder processing loop such that both will generate identical predictions (e.g. intra- and inter predictions) and/or re-constructions for processing, i.e. coding, the subsequent blocks.

In the following embodiments of a video coding system10, a video encoder20and a video decoder30are described based onFIGS. 1 to 3.

FIG. 1Ais a schematic block diagram illustrating an example coding system10, e.g. a video coding system10(or short coding system10) that may utilize techniques of this present disclosure. Video encoder20(or short encoder20) and video decoder30(or short decoder30) of video coding system10represent examples of devices that may be configured to perform techniques in accordance with various examples described in the present disclosure.

As shown inFIG. 1A, the coding system10comprises a source device12configured to provide encoded picture data21, e.g., to a destination device14, for decoding the encoded picture data13.

The source device12comprises an encoder20, and may additionally, i.e. optionally, comprise a picture source16, a pre-processor (or pre-processing unit)18, e.g. a picture pre-processor18, and a communication interface or communication unit22.

The picture source16may comprise or be any kind of picture capturing device, for example a camera for capturing a real-world picture, and/or any kind of a picture generating device, for example, a computer-graphics processor, for generating a computer animated picture, or any kind of other device for obtaining and/or providing a real-world picture, a computer generated picture (e.g. a screen content, a virtual reality (VR) picture) and/or any combination thereof (e.g. an augmented reality (AR) picture). The picture source may be any kind of memory or storage storing any of the aforementioned pictures.

In distinction to the pre-processor18and the processing performed by the pre-processing unit18, the picture or picture data17may also be referred to as raw picture or raw picture data17.

Pre-processor18is configured to receive the (raw) picture data17and to perform pre-processing on the picture data17to obtain a pre-processed picture19or pre-processed picture data19. Pre-processing performed by the pre-processor18may, e.g., comprise trimming, color format conversion (e.g. from RGB to YCbCr), color correction, or de-noising. It can be understood that the pre-processing unit18may be optional component.

The video encoder20is configured to receive the pre-processed picture data19and provide encoded picture data21(further details will be described below, e.g., based onFIG. 2).

Communication interface22of the source device12may be configured to receive the encoded picture data21and to transmit the encoded picture data21(or any further processed version thereof) over communication channel13to another device, e.g. the destination device14or any other device, for storage or direct reconstruction.

The destination device14comprises a decoder30(e.g. a video decoder30), and may additionally, i.e. optionally, comprise a communication interface or communication unit28, a post-processor32(or post-processing unit32) and a display device34.

The communication interface28of the destination device14is configured to receive the encoded picture data21(or any further processed version thereof), e.g. directly from the source device12or from any other source, e.g. a storage device, e.g. an encoded picture data storage device, and provide the encoded picture data21to the decoder30.

The communication interface22and the communication interface28may be configured to transmit or receive the encoded picture data21or encoded data13via a direct communication link between the source device12and the destination device14, e.g. a direct wired or wireless connection, or via any kind of network, e.g. a wired or wireless network or any combination thereof, or any kind of private and public network, or any kind of combination thereof.

The communication interface22may be, e.g., configured to package the encoded picture data21into an appropriate format, e.g. packets, and/or process the encoded picture data using any kind of transmission encoding or processing for transmission over a communication link or communication network.

The communication interface28, forming the counterpart of the communication interface22, may be, e.g., configured to receive the transmitted data and process the transmission data using any kind of corresponding transmission decoding or processing and/or de-packaging to obtain the encoded picture data21.

Both, communication interface22and communication interface28may be configured as unidirectional communication interfaces as indicated by the arrow for the communication channel13inFIG. 1Apointing from the source device12to the destination device14, or bi-directional communication interfaces, and may be configured, e.g. to send and receive messages, e.g. to set up a connection, to acknowledge and exchange any other information related to the communication link and/or data transmission, e.g. encoded picture data transmission.

The decoder30is configured to receive the encoded picture data21and provide decoded picture data31or a decoded picture31(further details will be described below, e.g., based onFIG. 3orFIG. 5).

The post-processor32of destination device14is configured to post-process the decoded picture data31(also called reconstructed picture data), e.g., the decoded picture31, to obtain post-processed picture data33, e.g. a post-processed picture33. The post-processing performed by the post-processing unit32may comprise, e.g. color format conversion (e.g. from YCbCr to RGB), color correction, trimming, or re-sampling, or any other processing, e.g. for preparing the decoded picture data31for display, e.g. by display device34.

The display device34of the destination device14is configured to receive the post-processed picture data33for displaying the picture, e.g. to a user or viewer. The display device34may be or comprise any kind of display for representing the reconstructed picture, e.g. an integrated or external display or monitor. The displays may, e.g. comprise liquid crystal displays (LCD), organic light emitting diodes (OLED) displays, plasma displays, projectors , micro LED displays, liquid crystal on silicon (LCoS), digital light processor (DLP) or any kind of other display.

AlthoughFIG. 1Adepicts the source device12and the destination device14as separate devices, embodiments of devices may also comprise both or both functionalities, the source device12or corresponding functionality and the destination device14or corresponding functionality. In such embodiments the source device12or corresponding functionality and the destination device14or corresponding functionality may be implemented using the same hardware and/or software or by separate hardware and/or software or any combination thereof.

As will be apparent for the skilled person based on the description, the existence and (exact) split of functionalities of the different units or functionalities within the source device12and/or destination device14as shown inFIG. 1Amay vary depending on the actual device and application.

The encoder20(e.g. a video encoder20) or the decoder30(e.g. a video decoder30) or both encoder20and decoder30may be implemented via processing circuitry as shown inFIG. 1B, such as one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, video coding dedicated or any combinations thereof. The encoder20may be implemented via processing circuitry46to embody the various modules as discussed with respect to encoder20ofFIG. 2and/or any other encoder system or subsystem described herein. The decoder30may be implemented via processing circuitry46to embody the various modules as discussed with respect to decoder30ofFIG. 3and/or any other decoder system or subsystem described herein. The processing circuitry may be configured to perform the various operations as discussed later. As shown inFIG. 5, if the techniques are implemented partially in software, a device may store instructions for the software in a suitable, non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Either of video encoder20and video decoder30may be integrated as part of a combined encoder/decoder (CODEC) in a single device, for example, as shown inFIG. 1B.

Source device12and destination device14may comprise any of a wide range of devices, including any kind of handheld or stationary devices, e.g. notebook or laptop computers, mobile phones, smart phones, tablets or tablet computers, cameras, desktop computers, set-top boxes, televisions, display devices, digital media players, video gaming consoles, video streaming devices(such as content services servers or content delivery servers), broadcast receiver device, broadcast transmitter device, or the like and may use no or any kind of operating system. In some cases, the source device12and the destination device14may be equipped for wireless communication. Thus, the source device12and the destination device14may be wireless communication devices.

For convenience of description, embodiments of the invention are described herein, for example, by reference to High-Efficiency Video Coding (HEVC) or to the reference software of Versatile Video coding (VVC), the next generation video coding standard developed by the Joint Collaboration Team on Video Coding (JCT-VC) of ITU-T Video Coding Experts Group (VCEG) and ISO/IEC Motion Picture Experts Group (MPEG). One of ordinary skill in the art will understand that embodiments of the invention are not limited to HEVC or VVC.

Encoder and Encoding Method

FIG. 2shows a schematic block diagram of an example video encoder20that is configured to implement the techniques of the present application. In the example ofFIG. 2, the video encoder20comprises an input201(or input interface201), a residual calculation unit204, a transform processing unit206, a quantization unit208, an inverse quantization unit210, and inverse transform processing unit212, a reconstruction unit214, a loop filter unit220, a decoded picture buffer (DPB)230, a mode selection unit260, an entropy encoding unit270and an output272(or output interface272). The mode selection unit260may include an inter prediction unit244, an intra prediction unit254and a partitioning unit262. Inter prediction unit244may include a motion estimation unit and a motion compensation unit (not shown). A video encoder20as shown inFIG. 2may also be referred to as hybrid video encoder or a video encoder according to a hybrid video codec.

The residual calculation unit204, the transform processing unit206, the quantization unit208, the mode selection unit260may be referred to as forming a forward signal path of the encoder20, whereas the inverse quantization unit210, the inverse transform processing unit212, the reconstruction unit214, the buffer216, the loop filter220, the decoded picture buffer (DPB)230, the inter prediction unit244and the intra-prediction unit254may be referred to as forming a backward signal path of the video encoder20, wherein the backward signal path of the video encoder20corresponds to the signal path of the decoder (see video decoder30inFIG. 3). The inverse quantization unit210, the inverse transform processing unit212, the reconstruction unit214, the loop filter220, the decoded picture buffer (DPB)230, the inter prediction unit244and the intra-prediction unit254are also referred to forming the “built-in decoder” of video encoder20.

The encoder20may be configured to receive, e.g. via input201, a picture17(or picture data17), e.g. picture of a sequence of pictures forming a video or video sequence. The received picture or picture data may also be a pre-processed picture19(or pre-processed picture data19). For sake of simplicity, the following description refers to the picture17. The picture17may also be referred to as current picture or picture to be coded (in particular in video coding to distinguish the current picture from other pictures, e.g. previously encoded and/or decoded pictures of the same video sequence, i.e. the video sequence which also comprises the current picture).

A (digital) picture is or can be regarded as a two-dimensional array or matrix of samples with intensity values. A sample in the array may also be referred to as pixel (short form of picture element) or a pa. The number of samples in horizontal and vertical direction (or axis) of the array or picture define the size and/or resolution of the picture. For representation of color, typically three color components are employed, i.e. the picture may be represented or include three sample arrays. In RBG format or color space a picture comprises a corresponding red, green and blue sample array. However, in video coding each pixel is typically represented in a luminance and chrominance format or color space, e.g. YCbCr, which comprises a luminance component indicated by Y (sometimes also L is used instead) and two chrominance components indicated by Cb and Cr. The luminance (or short luma) component Y represents the brightness or grey level intensity (e.g. like in a grey-scale picture), while the two chrominance (or short chroma) components Cb and Cr represent the chromaticity or color information components. Accordingly, a picture in YCbCr format comprises a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (Cb and Cr). Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, the process is also known as color transformation or conversion. If a picture is monochrome, the picture may comprise only a luminance sample array. Accordingly, a picture may be, for example, an array of luma samples in monochrome format or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 colour format.

Embodiments of the video encoder20may comprise a picture partitioning unit (not depicted inFIG. 2) configured to partition the picture17into a plurality of (typically non-overlapping) picture blocks203. These blocks may also be referred to as root blocks, macro blocks (H.264/AVC) or coding tree blocks (CTB) or coding tree units (CTU) (H.265/HEVC and VVC). The picture-partitioning unit may be configured to use the same block size for all pictures of a video sequence and the corresponding grid defining the block size, or to change the block size between pictures or subsets or groups of pictures, and partition each picture into the corresponding blocks.

In further embodiments, the video encoder may be configured to receive directly a block203of the picture17, e.g. one, several or all blocks forming the picture17. The picture block203may also be referred to as the current picture block or the picture block to be coded.

Like the picture17, the picture block203again is or can be regarded as a two-dimensional array or matrix of samples with intensity values (sample values), although of smaller dimension than the picture17. In other words, the block203may comprise, e.g., one sample array (e.g. a luma array in case of a monochrome picture17, or a luma or chroma array in case of a color picture) or three sample arrays (e.g. a luma and two chroma arrays in case of a color picture17) or any other number and/or kind of arrays depending on the color format applied. The number of samples in horizontal and vertical direction (or axis) of the block203define the size of block203. Accordingly, a block may, for example, an M×N (M-column by N-row) array of samples, or an M×N array of transform coefficients.

Embodiments of the video encoder20as shown inFIG. 2may be configured to encode the picture17block by block, e.g. the encoding and prediction is performed per block203.

Embodiments of the video encoder20as shown inFIG. 2may be further configured to partition and/or encode the picture by using slices (also referred to as video slices), wherein a picture may be partitioned into or encoded using one or more slices (typically non-overlapping), and each slice may comprise one or more blocks (e.g. CTUs).

Embodiments of the video encoder20as shown inFIG. 2may be further configured to partition and/or encode the picture by using tile groups (also referred to as video tile groups) and/or tiles (also referred to as video tiles), wherein a picture may be partitioned into or encoded using one or more tile groups (typically non-overlapping), and each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g. complete or fractional blocks.

Residual Calculation

The residual calculation unit204may be configured to calculate a residual block205(also referred to as residual205) based on the picture block203and a prediction block265(further details about the prediction block265are provided later), e.g. by subtracting sample values of the prediction block265from sample values of the picture block203, sample by sample (pixel by pixel) to obtain the residual block205in the sample domain.

Transform

The transform processing unit206may be configured to apply a transform, e.g. a discrete cosine transform (DCT) or discrete sine transform (DST), on the sample values of the residual block205to obtain transform coefficients207in a transform domain. The transform coefficients207may also be referred to as transform residual coefficients and represent the residual block205in the transform domain.

The transform processing unit206may be configured to apply integer approximations of DCT/DST, such as the transforms specified for H.265/HEVC. Compared to an orthogonal DCT transform, such integer approximations are typically scaled by a certain factor. In order to preserve the norm of the residual block which is processed by forward and inverse transforms, additional scaling factors are applied as part of the transform process. The scaling factors are typically chosen based on certain constraints like scaling factors being a power of two for shift operations, bit depth of the transform coefficients, tradeoff between accuracy and implementation costs, etc. Specific scaling factors are, for example, specified for the inverse transform, e.g. by inverse transform processing unit212(and the corresponding inverse transform, e.g. by inverse transform processing unit312at video decoder30) and corresponding scaling factors for the forward transform, e.g. by transform processing unit206, at an encoder20may be specified accordingly.

Embodiments of the video encoder20(respectively transform processing unit206) may be configured to output transform parameters, e.g. a type of transform or transforms, e.g. directly or encoded or compressed via the entropy encoding unit270, so that, e.g., the video decoder30may receive and use the transform parameters for decoding.

Quantization

The quantization unit208may be configured to quantize the transform coefficients207to obtain quantized coefficients209, e.g. by applying scalar quantization or vector quantization. The quantized coefficients209may also be referred to as quantized transform coefficients209or quantized residual coefficients209.

The quantization process may reduce the bit depth associated with some or all of the transform coefficients207. For example, an n-bit transform coefficient may be rounded down to an m-bit Transform coefficient during quantization, where n is greater than m. The degree of quantization may be modified by adjusting a quantization parameter (QP). For example, for scalar quantization, different scaling may be applied to achieve finer or coarser quantization. Smaller quantization step sizes correspond to finer quantization, whereas larger quantization step sizes correspond to coarser quantization. The applicable quantization step size may be indicated by a quantization parameter (QP). The quantization parameter may for example be an index to a predefined set of applicable quantization step sizes. For example, small quantization parameters may correspond to fine quantization (small quantization step sizes) and large quantization parameters may correspond to coarse quantization (large quantization step sizes) or vice versa. The quantization may include division by a quantization step size and a corresponding and/or the inverse dequantization, e.g. by inverse quantization unit210, may include multiplication by the quantization step size. Embodiments according to some standards, e.g., HEVC, may be configured to use a quantization parameter to determine the quantization step size. Generally, the quantization step size may be calculated based on a quantization parameter using fixed-point approximation of an equation including division. Additional scaling factors may be introduced for quantization and dequantization to restore the norm of the residual block, which might be modified because of the scaling used in the fixed-point approximation of the equation for quantization step size and quantization parameter. In one example implementation, the scaling of the inverse transform and dequantization might be combined. Alternatively, customized quantization tables may be used and signaled from an encoder to a decoder, e.g. in a bitstream. The quantization is a lossy operation, wherein the loss increases with increasing quantization step sizes.

Embodiments of the video encoder20(respectively quantization unit208) may be configured to output quantization parameters (QP), e.g. directly or encoded via the entropy encoding unit270, so that, e.g., the video decoder30may receive and apply the quantization parameters for decoding.

Inverse Quantization

The inverse quantization unit210is configured to apply the inverse quantization of the quantization unit208on the quantized coefficients to obtain dequantized coefficients211, e.g. by applying the inverse of the quantization scheme applied by the quantization unit208based on or using the same quantization step size as the quantization unit208. The dequantized coefficients211may also be referred to as dequantized residual coefficients211and correspond—although typically not identical to the transform coefficients due to the loss by quantization—to the transform coefficients207.

Inverse Transform

The inverse transform processing unit212is configured to apply the inverse transform of the transform applied by the transform processing unit206, e.g. an inverse discrete cosine transform (DCT) or inverse discrete sine transform (DST) or other inverse transforms, to obtain a reconstructed residual block213(or corresponding dequantized coefficients211) in the sample domain. The reconstructed residual block213may also be referred to as transform block213.

Reconstruction

The reconstruction unit214(e.g. adder or summer214) is configured to add the transform block213(i.e. reconstructed residual block213) to the prediction block265to obtain a reconstructed block215in the sample domain, e.g. by adding—sample by sample—the sample values of the reconstructed residual block213and the sample values of the prediction block265.

Filtering

The loop filter unit220(or short “loop filter”220), is configured to filter the reconstructed block215to obtain a filtered block221, or in general, to filter reconstructed samples to obtain filtered samples. The loop filter unit is, e.g., configured to smooth pixel transitions, or otherwise improve the video quality. The loop filter unit220may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof. Although the loop filter unit220is shown inFIG. 2as being an in loop filter, in other configurations, the loop filter unit220may be implemented as a post loop filter. The filtered block221may also be referred to as filtered reconstructed block221.

Embodiments of the video encoder20(respectively loop filter unit220) may be configured to output loop filter parameters (such as sample adaptive offset information), e.g. directly or encoded via the entropy encoding unit270, so that, e.g., a decoder30may receive and apply the same loop filter parameters or respective loop filters for decoding.

Decoded Picture Buffer

The decoded picture buffer (DPB)230may be a memory that stores reference pictures, or in general reference picture data, for encoding video data by video encoder20. The DPB230may be formed by any of a variety of memory devices, such as dynamic random access memory (DRAM), including synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The decoded picture buffer (DPB)230may be configured to store one or more filtered blocks221. The decoded picture buffer230may be further configured to store other previously filtered blocks, e.g. previously reconstructed and filtered blocks221, of the same current picture or of different pictures, e.g. previously reconstructed pictures, and may provide complete previously reconstructed, i.e. decoded, pictures (and corresponding reference blocks and samples) and/or a partially reconstructed current picture (and corresponding reference blocks and samples), for example for inter prediction. The decoded picture buffer (DPB)230may be also configured to store one or more unfiltered reconstructed blocks215, or in general unfiltered reconstructed samples, e.g. if the reconstructed block215is not filtered by loop filter unit220, or any other further processed version of the reconstructed blocks or samples.

The mode selection unit260comprises partitioning unit262, inter-prediction unit244and intra-prediction unit254, and is configured to receive or obtain original picture data, e.g. an original block203(current block203of the current picture17), and reconstructed picture data, e.g. filtered and/or unfiltered reconstructed samples or blocks of the same (current) picture and/or from one or a plurality of previously decoded pictures, e.g. from decoded picture buffer230or other buffers (e.g. line buffer, not shown). The reconstructed picture data is used as reference picture data for prediction, e.g. inter-prediction or intra-prediction, to obtain a prediction block265or predictor265.

Mode selection unit260may be configured to determine or select a partitioning for a current block prediction mode (including no partitioning) and a prediction mode (e.g. an intra or inter prediction mode) and generate a corresponding prediction block265, which is used for the calculation of the residual block205and for the reconstruction of the reconstructed block215.

Embodiments of the mode selection unit260may be configured to select the partitioning and the prediction mode (e.g. from those supported by or available for mode selection unit260), which provide the best match or in other words the minimum residual (minimum residual means better compression for transmission or storage), or a minimum signaling overhead (minimum signaling overhead means better compression for transmission or storage), or which considers or balances both. The mode selection unit260may be configured to determine the partitioning and prediction mode based on rate distortion optimization (RDO), i.e. select the prediction mode, which provides a minimum rate distortion. Terms like “best”, “minimum”, “optimum” etc. in this context do not necessarily refer to an overall “best”, “minimum”, “optimum”, etc. but may also refer to the fulfillment of a termination or selection criterion like a value exceeding or falling below a threshold or other constraints leading potentially to a “sub-optimum selection” but reducing complexity and processing time.

In other words, the partitioning unit262may be configured to partition the block203into smaller block partitions or sub-blocks (which form blocks again), e.g. iteratively using quad-tree-partitioning (QT), binary partitioning (BT) or triple-tree-partitioning (TT) or any combination thereof, and to perform, e.g., the prediction for each of the block partitions or sub-blocks, wherein the mode selection comprises the selection of the tree-structure of the partitioned block203and the prediction modes are applied to each of the block partitions or sub-blocks.

In the following the partitioning (e.g. by partitioning unit262) and prediction processing (by inter-prediction unit244and intra-prediction unit254) performed by an example video encoder20will be explained in more detail.

Partitioning

The partitioning unit262may partition (or split) a current block203into smaller partitions, e.g. smaller blocks of square or rectangular size. These smaller blocks (which may also be referred to as sub-blocks) may be further partitioned into even smaller partitions. This is also referred to tree-partitioning or hierarchical tree-partitioning, wherein a root block, e.g. at root tree-level 0 (hierarchy-level 0, depth 0), may be recursively partitioned, e.g. partitioned into two or more blocks of a next lower tree-level, e.g. nodes at tree-level 1 (hierarchy-level 1, depth 1), wherein these blocks may be again partitioned into two or more blocks of a next lower level, e.g. tree-level 2 (hierarchy-level 2, depth 2), etc. until the partitioning is terminated, e.g. because a termination criterion is fulfilled, e.g. a maximum tree depth or minimum block size is reached. Blocks, which are not further partitioned, are also referred to as leaf-blocks or leaf nodes of the tree. A tree using partitioning into two partitions is referred to as binary-tree (BT), a tree using partitioning into three partitions is referred to as ternary-tree (TT), and a tree using partitioning into four partitions is referred to as quad-tree (QT).

As mentioned before, the term “block” as used herein may be a portion, in particular a square or rectangular portion, of a picture. With reference, for example, to HEVC and VVC, the block may be or correspond to a coding tree unit (CTU), a coding unit (CU), prediction unit (PU), and transform unit (TU) and/or to the corresponding blocks, e.g. a coding tree block (CTB), a coding block (CB), a transform block (TB) or prediction block (PB).

For example, a coding tree unit (CTU) may be or comprise a CTB of luma samples, two corresponding CTBs of chroma samples of a picture that has three sample arrays, or a CTB of samples of a monochrome picture or a picture that is coded using three separate colour planes and syntax structures used to code the samples. Correspondingly, a coding tree block (CTB) may be an N×N block of samples for some value of N such that the division of a component into CTBs is a partitioning. A coding unit (CU) may be or comprise a coding block of luma samples, two corresponding coding blocks of chroma samples of a picture that has three sample arrays, or a coding block of samples of a monochrome picture or a picture that is coded using three separate colour planes and syntax structures used to code the samples. Correspondingly, a coding block (CB) may be an M×N block of samples for some values of M and N such that the division of a CTB into coding blocks is a partitioning.

In embodiments, e.g., according to HEVC, a coding tree unit (CTU) may be split into CUs by using a quad-tree structure denoted as coding tree. The decision whether to code a picture area using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level. Each CU can be further split into one, two or four PUs according to the PU splitting type. Inside one PU, the same prediction process is applied and the relevant information is transmitted to the decoder on a PU basis. After obtaining the residual block by applying the prediction process based on the PU splitting type, a CU can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for the CU.

In embodiments, e.g., according to the latest video coding standard currently in development, which is referred to as Versatile Video Coding (VVC), a combined Quad-tree and binary tree (QTBT) partitioning is, for example, used to partition a coding block. In the QTBT block structure, a CU can have either a square or a rectangular shape. For example, a coding tree unit (CTU) is first partitioned by a quadtree structure. The quadtree leaf nodes are further partitioned by a binary tree or ternary (or triple) tree structure. The partitioning tree leaf nodes are called coding units (CUs), and that segmentation is used for prediction and transform processing without any further partitioning. This means that the CU, PU and TU have the same block size in the QTBT coding block structure. In parallel, multiple partition, for example, triple tree partition may be used together with the QTBT block structure.

In one example, the mode selection unit260of video encoder20may be configured to perform any combination of the partitioning techniques described herein.

As described above, the video encoder20is configured to determine or select the best or an optimum prediction mode from a set of (e.g., pre-determined) prediction modes. The set of prediction modes may comprise, e.g., intra-prediction modes and/or inter-prediction modes.

The set of intra-prediction modes may comprise35different intra-prediction modes, e.g. non-directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined in HEVC, or may comprise67different intra-prediction modes, e.g. non-directional modes like DC (or mean) mode and planar mode, or directional modes, e.g. as defined for VVC.

The intra-prediction unit254is configured to use reconstructed samples of neighboring blocks of the same current picture to generate an intra-prediction block265according to an intra-prediction mode of the set of intra-prediction modes.

The intra prediction unit254(or in general the mode selection unit260) is further configured to output intra-prediction parameters (or in general information indicative of the selected intra prediction mode for the block) to the entropy encoding unit270in form of syntax elements266for inclusion into the encoded picture data21, so that, e.g., the video decoder30may receive and use the prediction parameters for decoding.

The set of (or possible) inter-prediction modes depends on the available reference pictures (i.e. previous at least partially decoded pictures, e.g. stored in DPB230) and other inter-prediction parameters, e.g. whether the whole reference picture or only a part, e.g. a search window area around the area of the current block, of the reference picture is used for searching for a best matching reference block, and/or e.g. whether pixel interpolation is applied, e.g. half/semi-pel and/or quarter-pel interpolation, or not.

Additional to the above prediction modes, a skip mode and/or a direct mode may be applied.

The inter prediction unit244may include a motion estimation (ME) unit and a motion compensation (MC) unit (both not shown inFIG. 2). The motion estimation unit may be configured to receive or obtain the picture block203(current picture block203of the current picture17) and a decoded picture231, or at least one or a plurality of previously reconstructed blocks, e.g. reconstructed blocks of one or a plurality of other/different previously decoded pictures231, for motion estimation. E.g., a video sequence may comprise the current picture and the previously decoded pictures231, or in other words, the current picture and the previously decoded pictures231may be part of or form a sequence of pictures forming a video sequence.

The encoder20may, e.g., be configured to select a reference block from a plurality of reference blocks of the same or different pictures of the plurality of other pictures and provide a reference picture (or reference picture index) and/or an offset (a spatial offset) between the position (x, y coordinates) of the reference block and the position of the current block as inter prediction parameters to the motion estimation unit. This offset is also called motion vector (MV).

The motion compensation unit is configured to obtain, e.g. receive, an inter prediction parameter and to perform inter prediction based on or using the inter prediction parameter to obtain an inter prediction block265. Motion compensation, performed by the motion compensation unit, may involve fetching or generating the prediction block based on the motion/block vector determined by motion estimation, possibly performing interpolations to sub-pixel precision. Interpolation filtering may generate additional pixel samples from known pixel samples, thus potentially increasing the number of candidate prediction blocks that may be used to code a picture block. Upon receiving the motion vector for the PU of the current picture block, the motion compensation unit may locate the prediction block to which the motion vector points in one of the reference picture lists.

The motion compensation unit may also generate syntax elements associated with the blocks and video slices for use by video decoder30in decoding the picture blocks of the video slice. In addition or as an alternative to slices and respective syntax elements, tile groups and/or tiles and respective syntax elements may be generated or used.

Entropy Coding

The entropy encoding unit270is configured to apply, for example, an entropy encoding algorithm or scheme (e.g. a variable length coding (VLC) scheme, an context adaptive VLC scheme (CAVLC), an arithmetic coding scheme, a binarization, a context adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding or another entropy encoding methodology or technique) or bypass (no compression) on the quantized coefficients209, inter prediction parameters, intra prediction parameters, loop filter parameters and/or other syntax elements to obtain encoded picture data21which can be output via the output272, e.g. in the form of an encoded bitstream21, so that, e.g., the video decoder30may receive and use the parameters for decoding, . The encoded bitstream21may be transmitted to video decoder30, or stored in a memory for later transmission or retrieval by video decoder30.

Other structural variations of the video encoder20can be used to encode the video stream. For example, a non-transform based encoder20can quantize the residual signal directly without the transform processing unit206for certain blocks or frames. In another implementation, an encoder20can have the quantization unit208and the inverse quantization unit210combined into a single unit.

Decoder and Decoding Method

FIG. 3shows an example of a video decoder30that is configured to implement the techniques of this present disclosure. The video decoder30is configured to receive encoded picture data21(e.g. encoded bitstream21), e.g. encoded by encoder20, to obtain a decoded picture331. The encoded picture data or bitstream comprises information for decoding the encoded picture data, e.g. data that represents picture blocks of an encoded video slice (and/or tile groups or tiles) and associated syntax elements.

In the example ofFIG. 3, the decoder30comprises an entropy decoding unit304, an inverse quantization unit310, an inverse transform processing unit312, a reconstruction unit314(e.g. a summer314), a loop filter320, a decoded picture buffer (DBP)330, a mode application unit360, an inter prediction unit344and an intra prediction unit354. Inter prediction unit344may be or include a motion compensation unit. Video decoder30may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder100fromFIG. 2.

As explained with regard to the encoder20, the inverse quantization unit210, the inverse transform processing unit212, the reconstruction unit214the loop filter220, the decoded picture buffer (DPB)230, the inter prediction unit344and the intra prediction unit354are also referred to as forming the “built-in decoder” of video encoder20. Accordingly, the inverse quantization unit310may be identical in function to the inverse quantization unit110, the inverse transform processing unit312may be identical in function to the inverse transform processing unit212, the reconstruction unit314may be identical in function to reconstruction unit214, the loop filter320may be identical in function to the loop filter220, and the decoded picture buffer330may be identical in function to the decoded picture buffer230. Therefore, the explanations provided for the respective units and functions of the video encoder20apply correspondingly to the respective units and functions of the video decoder30.

Entropy Decoding

The entropy decoding unit304is configured to parse the bitstream21(or in general encoded picture data21) and perform, for example, entropy decoding to the encoded picture data21to obtain, e.g., quantized coefficients309and/or decoded coding parameters (not shown inFIG. 3), e.g. any or all of inter prediction parameters (e.g. reference picture index and motion vector), intra prediction parameter (e.g. intra prediction mode or index), transform parameters, quantization parameters, loop filter parameters, and/or other syntax elements. Entropy decoding unit304maybe configured to apply the decoding algorithms or schemes corresponding to the encoding schemes as described with regard to the entropy-encoding unit270of the encoder20. Entropy decoding unit304may be further configured to provide inter prediction parameters, one or more intra prediction parameters and/or other syntax elements to the mode application unit360and other parameters to other units of the decoder30. The video decoder30may receive the syntax elements at the video slice level and/or the video block level. In addition or as an alternative to slices and respective syntax elements, tile groups and/or tiles and respective syntax elements may be received and/or used.

Inverse Quantization

The inverse quantization unit310may be configured to receive quantization parameters (QP) (or in general information related to the inverse quantization) and quantized coefficients from the encoded picture data21(e.g. by parsing and/or decoding, e.g. by entropy decoding unit304) and to apply based on the quantization parameters an inverse quantization on the decoded quantized coefficients309to obtain dequantized coefficients311, which may also be referred to as transform coefficients311. The inverse quantization process may include use of a quantization parameter determined by the video encoder20for each video block in the video slice (or tile or tile group) to determine a degree of quantization and, likewise, a degree of inverse quantization that should be applied.

Inverse Transform

Inverse transform processing unit312may be configured to receive dequantized coefficients311, also referred to as transform coefficients311, and to apply a transform to the dequantized coefficients311in order to obtain reconstructed residual blocks213in the sample domain. The reconstructed residual blocks213may also be referred to as transform blocks313. The transform may be an inverse transform, e.g., an inverse DCT, an inverse DST, an inverse integer transform, or a conceptually similar inverse transform process. The inverse transform processing unit312may be further configured to receive transform parameters or corresponding information from the encoded picture data21(e.g. by parsing and/or decoding, e.g. by entropy decoding unit304) to determine the transform to be applied to the dequantized coefficients311.

Reconstruction

The reconstruction unit314(e.g. adder or summer314) may be configured to add the reconstructed residual block313, to the prediction block365to obtain a reconstructed block315in the sample domain, e.g. by adding the sample values of the reconstructed residual block313and the sample values of the prediction block365.

Filtering

The loop filter unit320(either in the coding loop or after the coding loop) is configured to filter the reconstructed block315to obtain a filtered block321, e.g. to smooth pixel transitions, or otherwise improve the video quality. The loop filter unit320may comprise one or more loop filters such as a de-blocking filter, a sample-adaptive offset (SAO) filter or one or more other filters, e.g. a bilateral filter, an adaptive loop filter (ALF), a sharpening, a smoothing filters or a collaborative filters, or any combination thereof. Although the loop filter unit320is shown inFIG. 3as being an in loop filter, in other configurations, the loop filter unit320may be implemented as a post loop filter.

Decoded Picture Buffer

The decoded video blocks321of a picture are then stored in a decoded picture buffer330, which stores the decoded pictures331as reference pictures for subsequent motion compensation for other pictures and/or for output respectively display.

The decoder30is configured to output the decoded picture331, e.g. via output332, for presentation or viewing to a user.

Prediction

The inter prediction unit344may be identical to the inter prediction unit244(in particular to the motion compensation unit) and the intra prediction unit354may be identical to the intra prediction unit254in function, and performs split or partitioning decisions and prediction based on the partitioning and/or prediction parameters or respective information received from the encoded picture data21(e.g. by parsing and/or decoding, e.g. by entropy decoding unit304). Mode application unit360may be configured to perform the prediction (intra or inter prediction) per block based on reconstructed pictures, blocks or respective samples (filtered or unfiltered) to obtain the prediction block365.

When the video slice is coded as an intra coded (I) slice, intra prediction unit354of mode application unit360is configured to generate a prediction block365for a picture block of the current video slice based on a signaled intra prediction mode and data from previously decoded blocks of the current picture. When the video picture is coded as an inter coded (i.e., B, or P) slice, an inter prediction unit344(e.g. motion compensation unit) of mode application unit360is configured to produce prediction blocks365for a video block of the current video slice based on the motion vectors and other syntax elements received from entropy decoding unit304. For inter prediction, the prediction blocks may be produced from one of the reference pictures within one of the reference picture lists. Video decoder30may construct the reference frame lists, List 0 and List 1, using default construction techniques based on reference pictures stored in DPB330. The same or similar may be applied for or by embodiments using tile groups (e.g. video tile groups) and/or tiles (e.g. video tiles) in addition or alternatively to slices (e.g. video slices), e.g. a video may be coded using I, P or B tile groups and/or tiles.

Mode application unit360is configured to determine the prediction information for a video block of the current video slice by parsing the motion vectors or related information and other syntax elements, and uses the prediction information to produce the prediction blocks for the current video block being decoded. For example, the mode application unit360uses some of the received syntax elements to determine a prediction mode (e.g., intra or inter prediction) used to code the video blocks of the video slice, an inter prediction slice type (e.g., B slice, P slice, or GPB slice), construction information for one or more of the reference picture lists for the slice, motion vectors for each inter encoded video block of the slice, inter prediction status for each inter coded video block of the slice, and other information to decode the video blocks in the current video slice. The same or similar may be applied for or by embodiments using tile groups (e.g. video tile groups) and/or tiles (e.g. video tiles) in addition or alternatively to slices (e.g. video slices), e.g. a video may be coded using I, P or B tile groups and/or tiles.

Embodiments of the video decoder30, as shown inFIG. 3, may be configured to partition and/or decode the picture by using slices (also referred to as video slices), wherein a picture may be partitioned into or decoded using one or more slices (typically non-overlapping), and each slice may comprise one or more blocks (e.g. CTUs).

Embodiments of the video decoder30, as shown inFIG. 3, may be configured to partition and/or decode the picture by using tile groups (also referred to as video tile groups) and/or tiles (also referred to as video tiles), wherein a picture may be partitioned into or decoded using one or more tile groups (typically non-overlapping), and each tile group may comprise, e.g. one or more blocks (e.g. CTUs) or one or more tiles, wherein each tile, e.g. may be of rectangular shape and may comprise one or more blocks (e.g. CTUs), e.g. complete or fractional blocks.

Other variations of the video decoder30can be used to decode the encoded picture data21. For example, the decoder30can produce the output video stream without the loop-filtering unit320. For example, a non-transform based decoder30can inverse-quantize the residual signal directly without the inverse-transform processing unit312for certain blocks or frames. In another implementation, the video decoder30can have the inverse-quantization unit310and the inverse-transform processing unit312combined into a single unit.

It should be understood that, in the encoder20and the decoder30, a processing result of a current step might be further processed and then output to the next step. For example, after interpolation filtering, motion vector derivation or loop filtering, a further operation, such as Clip or shift, may be performed on the processing result of the interpolation filtering, motion vector derivation or loop filtering.

It should be noted that further operations might be applied to the derived motion vectors of current block (including but not limit to control point motion vectors of affine mode, sub-block motion vectors in affine, planar, ATMVP modes, temporal motion vectors, and so on). For example, the value of motion vector is constrained to a predefined range according to its representing bit. If the representing bit of motion vector is bitDepth, then the range is −2{circumflex over ( )}(bitDepth-1)˜2{circumflex over ( )}(bitDepth-1)−1, where “A” means exponentiation. For example, if bitDepth is set equal to 16, the range is −32768˜32767; if bitDepth is set equal to 18, the range is −131072˜131071. For example, the value of the derived motion vector (e.g. the MVs of four 4×4 sub-blocks within one 8×8 block) is constrained such that the max difference between integer parts of the four 4×4 sub-block MVs is no more than N pixels, such as no more than 1 pixel. Here provides two methods for constraining the motion vector according to the bitDepth.

Method 1: remove the overflow MSB (most significant bit) by flowing operations

where mvx is a horizontal component of a motion vector of an image block or a sub-block, mvy is a vertical component of a motion vector of an image block or a sub-block, and ux and uy indicates an intermediate value;

For example, if the value of mvx is −32769, after applying formula (1) and (2), the resulting value is 32767. In computer system, decimal numbers are stored as two's complement. The two's complement of −32769 is 1,0111,1111,1111,1111 (17 bits), then the MSB is discarded, so the resulting two's complement is 0111,1111,1111,1111 (decimal number is 32767), which is same as the output by applying formula (1) and (2).

The operations may be applied during the sum of mvp and mvd, as shown in formula (5) to (8).

Method 2: remove the overflow MSB by clipping the value

where vx is a horizontal component of a motion vector of an image block or a sub-block, vy is a vertical component of a motion vector of an image block or a sub-block; x, y and z respectively correspond to three input value of the MV clipping process, and the definition of function Clip3 is as follow:

FIG. 4is a schematic diagram of a video coding device400according to an embodiment of the disclosure. The video coding device400is suitable for implementing the disclosed embodiments as described herein. In an embodiment, the video coding device400may be a decoder such as video decoder30ofFIG. 1Aor an encoder such as video encoder20ofFIG. 1A.

The video coding device400comprises ingress ports410(or input ports410) and receiver units (Rx)420for receiving data; a processor, logic unit, or central processing unit (CPU)430to process the data; transmitter units (Tx)440and egress ports450(or output ports450) for transmitting the data; and a memory460for storing the data. The video coding device400may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components coupled to the ingress ports410, the receiver units420, the transmitter units440, and the egress ports450for egress or ingress of optical or electrical signals.

The processor430is implemented by hardware and software. The processor430may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), FPGAs, ASICs, and DSPs. The processor430is in communication with the ingress ports410, receiver units420, transmitter units440, egress ports450, and memory460. The processor430comprises a coding module470. The coding module470implements the disclosed embodiments described above. For instance, the coding module470implements, processes, prepares, or provides the various coding operations. The inclusion of the coding module470therefore provides a substantial improvement to the functionality of the video coding device400and effects the transformation of the video coding device400to a different state. Alternatively, the coding module470is implemented as instructions stored in the memory460and executed by the processor430.

FIG. 5is a simplified block diagram of an apparatus500that may be used as either or both of the source device12and the destination device14fromFIG. 1according to an exemplary embodiment.

A processor502in the apparatus500can be a central processing unit. Alternatively, the processor502can be any other type of device, or multiple devices, capable of manipulating or processing information now existing or hereafter developed. Although the disclosed implementations can be practiced with a single processor as shown, e.g., the processor502, advantages in speed and efficiency can be achieved using more than one processor.

A memory504in the apparatus500can be a read only memory (ROM) device or a random access memory (RAM) device in an implementation. Any other suitable type of storage device can be used as the memory504. The memory504can include code and data506that is accessed by the processor502using a bus512. The memory504can further include an operating system508and application programs510, the application programs510including at least one program that permits the processor502to perform the methods described here. For example, the application programs510can include applications 1 through N, which further include a video coding application that performs the methods described here.

The apparatus500can also include one or more output devices, such as a display518. The display518may be, in one example, a touch sensitive display that combines a display with a touch sensitive element that is operable to sense touch inputs. The display518can be coupled to the processor502via the bus512.

Although depicted here as a single bus, the bus512of the apparatus500can be composed of multiple buses. Further, the secondary storage514can be directly coupled to the other components of the apparatus500or can be accessed via a network and can comprise a single integrated unit such as a memory card or multiple units such as multiple memory cards. The apparatus500can thus be implemented in a wide variety of configurations.

Position-dependent intra prediction combination, PDPC, (also known as position-dependent intra prediction sample filtering process) is a post-prediction filtering process applied to predicted blocks, these predicted blocks are generated according to intra prediction modes such as DC mode (INTRA_DC), planer mode (INTRA_PLANAR), and a subset of directional (angular) modes including horizontal (INTRA_ANGULAR18) mode and vertical (INTRA_ANGULAR50) mode. Directional modes excluding horizontal (INTRA_ANGULAR18) and vertical (INTRA_ANGULAR50) are referred to as oblique directional (angular) modes or skew directional (angular) modes. The current version of the VVC specification draft (document JVET-P2001-vE: B. Bross, J. Chen, S. Liu, Y.-K. Wang, “Versatile Video Coding (Draft 7),” output document JVET-P2001 of the 16th JVET meeting, Geneva, Switzerland; this document is contained in file JVET-P2001-v14: http://phenix.it-sudparis.eu/jvet/doc_end_user/documents/16_Geneva/wg11LIVET-P2001-v14.zip) prescribes the following sequence of steps in Section 8.4.5.2.14 “Position-dependent intra prediction sample filtering process” to perform PDPC:

Inputs to this process are:

If predModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18 and nScale is equal to or greater than 0, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50 and nScale is equal to or greater than 0, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Inputs to this process are:

the intra prediction mode preModeIntra,
a variable refIdx specifying the intra prediction reference line index,
a variable nTbW specifying the transform block width,
a variable nTbH specifying the transform block height,
a variable refW specifying the reference samples width,
a variable refH specifying the reference samples height,
a variable nCbW specifying the coding block width,
a variable nCbH specifying the coding block height,
a variable refFilterFlag specifying the value of reference filter flag,
a variable cIdx specifying the colour component of the current block,
the neighbouring samples p[x][y], with x=−1−refIdx, y=−1−refIdx . . . refH−1 and x=−refIdx . . . refW−1, y=−1−refIdx.

The variable nTbS is set equal to (Log2 (nTbW)+Log2 (nTbH))>>1.

The variable filterFlag is derived as follows:

If one or more of the following conditions is true, filterFlag is set equal to 0:

refFilterFlag is equal to 1;

refIdx is not equal to 0;

IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT.

Otherwise, the following applies:

The variable minDistVerHor is set equal to Min(Abs(predModeIntra−50), Abs(predModeIntra−18)).

The variable intraHorVerDistThres[nTbS] is specified in Table 1.

The variable filterFlag is derived as follows:If minDistVerHor is greater than intraHorVerDistThres[nTbS], filterFlag is set equal to 1.Otherwise, filterFlag is set equal to 0.

FIG. 6illustrates the 93 prediction directions, where the dashed directions are associated with the wide-angle modes that are only applied to non-square blocks. Table 2 specifies the mapping table between preModeIntra and the angle parameter intraPredAngle.

The inverse angle parameter invAngle is derived based on intraPredAngle as follows:

If preModeIntra is greater than or equal to 34, the following ordered steps apply:
1. The reference sample array ref[x] is specified as follows:

The following applies:

If intraPredAngle is less than 0, the main reference sample array is extended as follows:

The index variable iIdx and the multiplication factor iFact are derived as follows:

If cIdx is equal to 0, the following applies:The interpolation filter coefficients fT[j] with j=0 . . . 3 are derived as follows:

fT[j]=filterFlag?fG[iFact][j]: fC[iFact][j].The value of the prediction samples predSamples[x][y] is derived as follows:

Otherwise (cIdx is not equal to 0), depending on the value of iFact, the following applies:If iFact is not equal to 0, the value of the prediction samples predSamples[x][y] is derived as follows:

Otherwise (predModeIntra is less than 34), the following ordered steps apply:
1. The reference sample array ref[x] is specified as follows:

The following applies:

If intraPredAngle is less than 0, the main reference sample array is extended as follows:

The additional samples ref[refH+refIdx+x] with

The index variable iIdx and the multiplication factor iFact are derived as follows:

If cIdx is equal to 0, the following applies:The interpolation filter coefficients fT[j] with j=0 . . . 3 are derived as follows:

fT[j]=filterFlag?fG[iFact][j]: fC[iFact][j].The value of the prediction samples predSamples[x][y] is derived as follows:

Otherwise (cIdx is not equal to 0), depending on the value of iFact, the following applies:If iFact is not equal to 0, the value of the prediction samples predSamples[x][y] is derived as follows:

Otherwise, the value of the prediction samples predSamples[x][y] is derived as follows:

Embodiments below describe a mechanism to terminate PDPC for oblique directional modes, when a derived value of the variable nScale is less than 0. For these embodiments, Section 8.4.5.2.14 “Position-dependent intra prediction sample filtering process” can be rewritten as follows:

Inputs to this process are:

The variable nScale is derived as follows:

If preModeIntra is greater than INTRA_ANGULAR50, nScale is set equal to Min(2, Log2(nTbH)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, if preModeIntra is less than INTRA_ANGULAR18, not equal to INTRA_PLANAR and not equal to INTRA_DC, nScale is set equal to Min(2, Log2(nTbW)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).

If the value of nScale is less than 0, process 8.4.5.2.14 is terminated, and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW−1, y=0 . . . nTbH−1.

If preModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Inputs to this process are:

The variable nScale is derived as follows:

If preModeIntra is equal to INTRA_PLANAR, INTRA_DC, INTRA_ANGULAR18, or INTRA_ANGULAR50, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).
Otherwise, nScale is set equal to Min(2, Log2(preModeIntra>INTRA_ANGULAR50?nTbH: nTbW)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
If the value of nScale is less than 0, process 8.4.5.2.14 is terminated, and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW −1, y=0 . . . nTbH−1.

If preModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Inputs to this process are:

The variable nScale is derived as follows:
If preModeIntra is equal to INTRA_PLANAR, INTRA_DC, INTRA_ANGULAR18, or INTRA_ANGULAR50, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).
Otherwise, nScale is set equal to Min(2, Log2(nTbS)−Floor(Log2(3*invAngle−2))+8), using nTbS equal to preModeIntra >INTRA_ANGULAR50?nTbH: nTbW and invAngle as specified in clause 8.4.5.2.12. If the value of nScale is less than 0, process 8.4.5.2.14 is terminated, and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW−1, y=0 . . . nTbH−1.

If preModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Other embodiments are a harmonization of PDPC with ISP (intra subpartition coding mode also known as intra prediction with subpartitions). In clause 8.4.5.2.5 “General intra sample prediction” of the current VVC specification draft (document JVET-P2001-vE: B. Bross, J. Chen, S. Liu, Y.-K. Wang, “Versatile Video Coding (Draft 7),” output document JVET-P2001 of the 16th JVET meeting, Geneva, Switzerland), the variables refW and refH are defined as follows:

General Intra Sample Prediction

Inputs to this process are:

a sample location (xTbCmp, yTbCmp) specifying the top-left sample of the current transform block relative to the top-left sample of the current picture,
a variable preModeIntra specifying the intra prediction mode,
a variable nTbW specifying the transform block width,
a variable nTbH specifying the transform block height,
a variable nCbW specifying the coding block width,
a variable nCbH specifying the coding block height,
a variable cIdx specifying the colour component of the current block.

The variables refW and refH are derived as follows:

If IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT or cIdx is not equal to 0, the following applies:

Otherwise (IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT and cIdx is equal to 0), the following applies:

Hence, the length of top and left reference sample sides is defined differently when ISP is enabled (IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT and cIdx is equal to 0) or when ISP is disabled (if IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT or cIdx is not equal to 0). It results in extended number of available reference samples that can be used for performing PDPC for some oblique directional intra prediction modes.

FIG. 7andFIG. 8illustrate two examples. Coding blocks701and801are split into2or4subpartitions also referred to as subblocks (exemplified as702and802inFIG. 7andFIG. 8, respectively). Top row of reference samples is denoted as711and811inFIG. 7andFIG. 8, respectively. Left column of reference samples is denoted as712and812inFIG. 7andFIG. 8, respectively. Top-left reference sample is denoted as713and813inFIG. 7andFIG. 8, respectively. When IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT and cIdx is equal to 0, either horizontal (ISP_HOR_SPLIT) or vertical (ISP_VER_SPLIT) splits are applied to a coding block. If vertical split (ISP_VER_SPLIT) is selected, nCbW is greater than nTbW as shown inFIG. 7. If horizontal split (ISP_HOR_SPLIT) is selected, nCbH is greater than nTbH as shown inFIG. 8. To enable PDPC for the extended subset of oblique directional modes, the formulas used to derive values of the variable nScale should be modified in Section 8.4.5.2.14 “Position-dependent intra prediction sample filtering process” as follows:

If preModeIntra is greater than INTRA_ANGULAR50, nScale is set equal to Min(2, Log2(refH−nTbH)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, if preModeIntra is less than INTRA_ANGULAR18, not equal to INTRA_PLANAR and not equal to INTRA_DC, nScale is set equal to Min(2, Log2(refW−nTbW)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.

Thus, in the above formulas to compute the variable nScale for oblique angular modes, the coding block height nCbH and the coding block width nCbW are used instead of the transform block height nTbH and the transform block width nTbW, respectively. In the formulas above, the coding block height nCbH is calculated as (refH−nTbH) and the coding block width nCbW as (refW−nTbW). Below, relevant embodiments are shown.

Inputs to this process are:

The variable nScale is derived as follows:
If preModeIntra is greater than INTRA_ANGULAR50, nScale is set equal to Min(2, Log2(refH−nTbH)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, if preModeIntra is less than INTRA_ANGULAR18, not equal to INTRA_PLANAR and not equal to INTRA_DC, nScale is set equal to Min(2, Log2(refW−nTbW)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).

If preModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18 and nScale is equal to or greater than 0, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50 and nScale is equal to or greater than 0, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, refL[x][y], refT[x][y], wT[y], and wL[x] are all set equal to 0.

Inputs to this process are:

The variable nScale is derived as follows:
If preModeIntra is greater than INTRA_ANGULAR50, nScale is set equal to Min(2, Log2(refH−nTbH)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12.
Otherwise, if preModeIntra is less than INTRA_ANGULAR18, not equal to INTRA_PLANAR and not equal to INTRA_DC, nScale is set equal to

Otherwise, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).

If the value of nScale is less than 0, process 8.4.5.2.14 is terminated, and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW−1, y=0 . . . nTbH−1.

If preModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if preModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if preModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Inputs to this process are:

The variable nScale is derived as follows:
If preModeIntra is equal to INTRA_PLANAR, INTRA_DC, INTRA_ANGULAR18, or INTRA_ANGULAR50, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).
Otherwise, nScale is set equal to Min(2, Log2(predModeIntra>INTRA_ANGULAR50?refH−nTbH:refW−nTbW)−Floor(Log2(3*invAngle−2))+8), using invAngle as specified in clause 8.4.5.2.12. If the value of nScale is less than 0, process 8.4.5.2.14 is terminated and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW−1, y=0 . . . nTbH−1.

If predModeIntra is equal to INTRA_PLANAR or INTRA_DC, the following applies:

Otherwise, if predModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if preModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if predModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Inputs to this process are:

The variable nScale is derived as follows:
If preModeIntra is equal to INTRA_PLANAR, INTRA_DC, INTRA_ANGULAR18, or INTRA_ANGULAR50, nScale is set to ((Log2(nTbW)+Log2(nTbH)−2)>>2).
Otherwise, nScale is set equal to Min(2, Log2(nCbS)−Floor(Log2(3*invAngle−2))+8), using nCbS equal to predModeIntra>INTRA_ANGULAR50?refH−nTbH: refW−nTbW and invAngle as specified in clause 8.4.5.2.12. If the value of nScale is less than 0, process 8.4.5.2.14 is terminated, and outputs of this process are set equal to the input predicted samples predSamples[x][y], with x=0 . . . nTbW−1, y=0 . . . nTbH−1.

Otherwise, if predModeIntra is equal to INTRA_ANGULAR18 or INTRA_ANGULAR50, the following applies:

Otherwise, if predModeIntra is less than INTRA_ANGULAR18, the following ordered steps apply:
1. The variables dXInt[y] and dX[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

Otherwise, if predModeIntra is greater than INTRA_ANGULAR50, the following ordered steps apply:
1. The variables dYInt[x] and dY[x][y] are derived as follows using invAngle as specified in clause 8.4.5.2.12 depending on intraPredMode:

2. The variables refL[x][y], refT[x][y], wT[y], and wL[x] are derived as follows:

FIG. 11illustrates a flowchart of a method according to an embodiment of the present disclosure. According toFIG. 11, it is disclosed a method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: (1601) obtaining a predicted sample value for a sample of the current coding block; (1603) obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; (1605) determining a first weight based on the scaling factor value; (1607) determining a second weight based on the scaling factor value; (1609) calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; (1611) obtaining a modified predicted sample value according to the additional value and the predicted sample value; and (1613) outputting the modified predicted sample value.

FIG. 12illustrates a decoder30according to an embodiment of the present disclosure. The decoder30ofFIG. 12is a decoder30for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit3001configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit3003configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first determining unit3005configured to determine a first weight value based on the scaling factor value; a second determining unit3007configured to determine a second weight based on the scaling factor value; a calculating unit3009configured to calculate an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; a third obtaining unit3011configured to obtain a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit (3013) configured to output the modified predicted sample value.

FIG. 13illustrates an encoder according to an embodiment of the present disclosure. The encoder20ofFIG. 13is an encoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising a first obtaining unit2001configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit2003configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first determining unit2005configured to determine a first weight based on the scaling factor value; a second determining unit2007configured to determine a second weight based on the scaling factor value; a calculating unit2009configured to calculate an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; a third obtaining unit2011configured to obtain a modified predicted sample value according to the additional value and the predicted sample value; and an outputting unit2013configured to output the modified predicted sample value.

FIG. 14illustrates a flowchart of a method according to a further embodiment of the present disclosure. According toFIG. 14it is disclosed a method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: (2601) obtaining a predicted sample value for a sample of the current coding block; (2603) obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; wherein in case the scaling factor value is greater than or equal to 0, (2605) performing the following processes: (2607) determining a first weight based on the scaling factor value; (2609) determining a second weight based on the scaling factor value; (2611) calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; (2613) obtaining a modified predicted sample value according to the additional value and the predicted sample value; and (2615) outputting the modified predicted sample value.

FIG. 14further illustrates that the method may comprise in case the scaling factor value is less than 0, (2617) outputting the predicted sample value.

FIG. 15illustrates a decoder30according to the further embodiment of the present disclosure. The decoder30ofFIG. 15is a decoder for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit3301configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit3303configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a processing unit3307, wherein, when the scaling factor value is greater than or equal to 0, the processing unit3307is configured to perform the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and the decoder comprises a first outputting unit (3315) configured to output the modified predicted sample value.

FIG. 15further illustrates that the decoder30may further comprise a second outputting unit3317wherein the second outputting unit3317is configured to output the predicted sample value in case the scaling factor value is less than 0.

FIG. 16illustrates an encoder20according to the further embodiment of the present disclosure. The decoder30ofFIG. 16is an encoder20for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit2301configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit2303configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a processing unit2307, wherein, when the scaling factor value is greater than or equal to 0, the processing unit is configured to perform the following processes: determining a first weight based on the scaling factor value; determining a second weight based on the scaling factor value; calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight; obtaining a modified predicted sample value according to the additional value and the predicted sample value; and the encoder20further comprises an outputting unit2315configured to output the modified predicted sample value.

The encoder20ofFIG. 16may further comprise a second outputting unit2317wherein the second outputting unit2317is configured to output the predicted sample value in case the scaling factor value is less than 0.

FIG. 17illustrates a flowchart of a method according to another embodiment of the present disclosure. According toFIG. 17it is disclosed a method for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, the method comprising: (3601) obtaining a predicted sample value for a sample of the current coding block; (3603) obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; wherein (3605) in case the intra prediction mode for the current coding block is angular mode, and when the scaling factor value is less than 0, (3617) outputting the predicted sample value; otherwise (3605) performing the following processes: (3607) determining a first weight based on the scaling factor value, (3609) determining a second weight based on the scaling factor value, (3611) calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, (3613) obtaining a modified predicted sample value according to the additional value and the predicted sample value; and (3615) outputting the modified predicted sample value.

FIG. 18illustrates a decoder30according to another embodiment of the present disclosure. The decoder30ofFIG. 18is a decoder30for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit3401configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit3403configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; a first outputting unit3417, the first outputting unit3417being configured to output the predicted sample in case the intra prediction mode for the current coding block is angular mode, and the scaling factor value is less than 0; and otherwise a processing unit3407configured to performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value; and the decoder30comprises a second outputting unit3415configured to output the modified predicted sample value.

FIG. 19illustrates an encoder20according to another embodiment of the present disclosure. The decoder30ofFIG. 19is an encoder20for an intra predicting process of a video block, wherein the block is a current coding block or a subpartition of the current coding block, comprising: a first obtaining unit2401configured to obtain a predicted sample value for a sample of the current coding block; a second obtaining unit2403configured to obtain a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block and/or a width of the current coding block; an first outputting unit2417, the first outputting unit2417being configured to output the predicted sample in case the intra prediction mode for the current coding block is angular mode, and the scaling factor value is less than 0; and otherwise a processing unit configured to performing the following processes: determining a first weight based on the scaling factor value, determining a second weight based on the scaling factor value, calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight, obtaining a modified predicted sample value according to the additional value and the predicted sample value; and the encoder20comprises a second outputting unit2415configured to output the modified predicted sample value.

The following provides an explanation of the applications of the encoding method as well as the decoding method as shown in the above-mentioned embodiments, and a system using them.

FIG. 9is a block diagram showing a content supply system3100for realizing content distribution service. This content supply system3100includes a capture device3102, a terminal device3106, and optionally includes a display3126. The capture device3102communicates with the terminal device3106over communication link3104. The communication link may include the communication channel13described above. The communication link3104includes but not limited to WIFI, Ethernet, Cable, wireless (3G/4G/5G), USB, or any kind of combination thereof, or the like.

The capture device3102generates data, and may encode the data by the encoding method as shown in the above embodiments. Alternatively, the capture device3102may distribute the data to a streaming server (not shown in the Figures), and the server encodes the data and transmits the encoded data to the terminal device3106. The capture device3102includes but not limited to camera, smart phone or Pad, computer or laptop, video conference system, PDA, vehicle mounted device, or a combination of any of them, or the like. For example, the capture device3102may include the source device12as described above. When the data includes video, the video encoder20included in the capture device3102may actually perform video encoding processing. When the data includes audio (i.e., voice), an audio encoder included in the capture device3102may actually perform audio encoding processing. For some practical scenarios, the capture device3102distributes the encoded video and audio data by multiplexing them together. For other practical scenarios, for example in the video conference system, the encoded audio data and the encoded video data are not multiplexed. Capture device3102distributes the encoded audio data and the encoded video data to the terminal device3106separately.

In the content supply system3100, the terminal device3106receives and reproduces the encoded data. The terminal device3106could be a device with data receiving and recovering capability, such as a smart phone or a Pad3108, a computer or a laptop3110, a network video recorder (NVR)/ digital video recorder (DVR)3112, TV3114, a set top box (STB)3116, a video conference system3118, a video surveillance system3120, a personal digital assistant (PDA)3122, a vehicle mounted device3124, or a combination of any of them, or the like capable of decoding the above-mentioned encoded data. For example, the terminal device3106may include the destination device14as described above. When the encoded data includes video, the video decoder30included in the terminal device is prioritized to perform video decoding. When the encoded data includes audio, an audio decoder included in the terminal device is prioritized to perform audio decoding processing.

For a terminal device with its display, for example, the smart phone or Pad3108, the computer or laptop3110, the network video recorder (NVR)/ digital video recorder (DVR)3112, the TV3114, the personal digital assistant (PDA)3122, or the vehicle mounted device3124, the terminal device can feed the decoded data to its display. For a terminal device equipped with no display, for example, STB3116, video conference system3118, or video surveillance system3120, an external display3126is contacted therein to receive and show the decoded data.

When each device in this system performs encoding or decoding, the picture-encoding device or the picture-decoding device, as shown in the above-mentioned embodiments, can be used.

FIG. 10is a diagram showing a structure of an example of the terminal device3106. After the terminal device3106receives stream from the capture device3102, the protocol proceeding unit3202analyzes the transmission protocol of the stream. The protocol includes but not limited to Real Time Streaming Protocol (RTSP), Hyper Text Transfer Protocol (HTTP), HTTP Live streaming protocol (HLS), MPEG-DASH, Real-time Transport protocol (RTP), Real Time Messaging Protocol (RTMP), or any kind of combination thereof, or the like.

After the protocol proceeding unit3202processes the stream, stream file is generated. The file is outputted to a demultiplexing unit3204. The demultiplexing unit3204can separate the multiplexed data into the encoded audio data and the encoded video data. As described above, for some practical scenarios, for example in the video conference system, the encoded audio data and the encoded video data are not multiplexed. In this situation, the encoded data is transmitted to a video decoder3206and an audio decoder3208without through the demultiplexing unit3204.

Via the demultiplexing processing, a video elementary stream (ES), an audio ES, and optionally a subtitle are generated. The video decoder3206, which includes the video decoder30as explained in the above-mentioned embodiments, decodes the video ES by the decoding method as shown in the above-mentioned embodiments to generate video frame, and feeds this data to the synchronous unit3212. The audio decoder3208, decodes the audio ES to generate audio frame, and feeds this data to the synchronous unit3212. Alternatively, the video frame may store in a buffer (not shown inFIG. 10) before feeding it to the synchronous unit3212. Similarly, the audio frame may store in a buffer (not shown inFIG. 10) before feeding it to the synchronous unit3212.

The synchronous unit3212synchronizes the video frame and the audio frame, and supplies the video/audio to a video/audio display3214. For example, the synchronous unit3212synchronizes the presentation of the video and audio information. Information may code in the syntax using time stamps concerning the presentation of coded audio and visual data and time stamps concerning the delivery of the data stream itself.

If a subtitle is included in the stream, the subtitle decoder3210decodes the subtitle, synchronizes it with the video frame and the audio frame, and supplies the video/audio/subtitle to a video/audio/subtitle display3216.

The present invention is not limited to the above-mentioned system, and either the picture-encoding device or the picture-decoding device in the above-mentioned embodiments can be incorporated into other system, for example, a car system.

Mathematical Operators

The mathematical operators used in this application are similar to those used in the C programming language. However, the results of integer division and arithmetic shift operations are defined more precisely, and additional operations are defined, such as exponentiation and real-valued division. Numbering and counting conventions generally begin from 0, e.g., “the first” is equivalent to the 0-th, “the second” is equivalent to the 1-th, etc.

Arithmetic Operators

The following arithmetic operators are defined as follows:

− Subtraction (as a two-argument operator) or negation (as a unary prefix operator)
* Multiplication, including matrix multiplication
xyExponentiation. Specifies x to the power of y. In other contexts, such notation is used for superscripting not intended for interpretation as exponentiation.

/ Integer division with truncation of the result toward zero. For example, 7/4 and −7/−4 are truncated to 1 and −7/4 and 7/−4 are truncated to −1.

÷ Used to denote division in mathematical equations where no truncation or rounding is intended.

Used to denote division in mathematical equations where no truncation or rounding is intended.

The summation of f(i) with i taking all integer values from x up to and including y.

x%y Modulus. Remainder of x divided by y, defined only for integers x and y with x>=0 and y>0.

Logical Operators

The following logical operators are defined as follows:

x && y Boolean logical “and” of x and y
x|y Boolean logical “or” of x and y
! Boolean logical “not”
x?y : z If x is TRUE or not equal to 0, evaluates to the value of y; otherwise, evaluates to the value of z.

Relational Operators

The following relational operators are defined as follows:

> Greater than
>= Greater than or equal to
< Less than
<= Less than or equal to

== Equal to

!= Not equal to

When a relational operator is applied to a syntax element or variable that has been assigned the value “na” (not applicable), the value “na” is treated as a distinct value for the syntax element or variable. The value “na” is considered not to be equal to any other value.

The following bit-wise operators are defined as follows:

& Bit-wise “and”. When operating on integer arguments, operates on a two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0.
| Bit-wise “or”. When operating on integer arguments, operates on a two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0.
{circumflex over ( )} Bit-wise “exclusive or”. When operating on integer arguments, operates on a two's complement representation of the integer value. When operating on a binary argument that contains fewer bits than another argument, the shorter argument is extended by adding more significant bits equal to 0.
x>>y Arithmetic right shift of a two's complement integer representation of x by y binary digits. This function is defined only for non-negative integer values of y. Bits shifted into the most significant bits (MSBs) as a result of the right shift have a value equal to the MSB of x prior to the shift operation.
x<<y Arithmetic left shift of a two's complement integer representation of x by y binary digits. This function is defined only for non-negative integer values of y. Bits shifted into the least significant bits (LSBs) as a result of the left shift have a value equal to 0.

Assignment operators

The following arithmetic operators are defined as follows:

= Assignment operator
++ Increment, i.e., x++ is equivalent to x=x+1; when used in an array index, evaluates to the value of the variable prior to the increment operation.
−− Decrement, i.e., x−− is equivalent to x=x−1; when used in an array index, evaluates to the value of the variable prior to the decrement operation.
+= Increment by amount specified, i.e., x+=3 is equivalent to x=x+3, and x+=(−3) is equivalent to x=x+(−3).
−=Decrement by amount specified, i.e., x−=3 is equivalent to x=x−3, and x−=(−3) is equivalent to x=x−(−3).

Range Notation

The following notation is used to specify a range of values:

x=y . . . .z x takes on integer values starting from y to z, inclusive, with x, y, and z being integer numbers and z being greater than y.

Mathematical Functions

The following mathematical functions are defined:

Asin(x) the trigonometric inverse sine function, operating on an argument x that is in the range of −1.0 to 1.0, inclusive, with an output value in the range of −π÷2 to π÷2, inclusive, in units of radians
Atan(x) the trigonometric inverse tangent function, operating on an argument x, with an output value in the range of −π÷2 to π÷2, inclusive, in units of radians

Ceil(x) the smallest integer greater than or equal to x.

Cos(x) the trigonometric cosine function operating on an argument x in units of radians.
Floor(x) the largest integer less than or equal to x.

Ln(x) the natural logarithm of x (the base-e logarithm, where e is the natural logarithm base constant 2.718 281 828 . . . .).
Log2(x) the base-2 logarithm of x.
Log10(x) the base-10 logarithm of x.

Sin(x) the trigonometric sine function operating on an argument x in units of radians

Tan(x) the trigonometric tangent function operating on an argument x in units of radians

Order of Operation Precedence

When an order of precedence in an expression is not indicated explicitly by use of parentheses, the following rules apply:

Operations of a higher precedence are evaluated before any operation of a lower precedence.
Operations of the same precedence are evaluated sequentially from left to right.

The table below specifies the precedence of operations from highest to lowest; a higher position in the table indicates a higher precedence.

For those operators that are also used in the C programming language, the order of precedence used in this Specification is the same as used in the C programming language.

Text Description of Logical Operations

In the text, a statement of logical operations as would be described mathematically in the following form:

else/* informative remark on remaining condition */statement n
may be described in the following manner . . . . as follows/ . . . . the following applies:

If condition 0, statement 0

Otherwise (informative remark on remaining condition), statement n.

statement n

may be described in the following manner
. . . . as follows/ . . . . the following applies:

If all of the following conditions are true, statement 0:condition 0acondition 0b

Otherwise, if one or more of the following conditions are true, statement 1:condition 1acondition 1bOtherwise, statement n

In the text, a statement of logical operations as would be described mathematically in the following form:

may be described in the following manner
When condition 0, statement 0
When condition 1, statement 1.

The present disclosure discloses the following further fourteen aspects.

1. An aspect of a method for intra predicting process of a video (or picture, frame) block (a block may be a current coding block or a subpartition of the current coding block), the method comprising:

obtaining a predicted sample value for a sample of the current coding block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode);

obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block (this process is for angular mode. And when the intra prediction mode for the current coding block is not a horizontal mode and is not a vertical mode, the scaling factor value is obtained according to a height of the block or a width of the block for DC mode, planar mode, horizontal and vertical angular modes) (in an example, both of the height and the width are used to obtain the scaling factor);

determining a first weight based on the scaling factor value;
determining a second weight based on the scaling factor value;
calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight;
obtaining a modified predicted sample value according to the additional value and the predicted sample value (in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value)
(in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

2. An aspect of the method according to aspect 1, wherein the height of the current coding block is equal to a value of refH−nTbH, the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block (or the block).

3. An aspect of the method according to aspects 1 or 2, wherein the width of the current coding block is equal to a value of refW−nTbW, the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block (or the block).

4. An aspect of a method for intra predicting process of a video (or picture, frame) block (a block may be a current coding block or a subpartition of the current coding block), the method comprising:

obtaining a predicted sample value for a sample of the current coding block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode);
obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block (this process is for angular mode. And when the intra prediction mode for the current coding block is not a horizontal mode and is not a vertical mode, the scaling factor value is obtained according to a height of the block or a width of the block for DC mode, planar mode, horizontal and vertical angular modes) (in an example, both of the height and the width are used to obtain the scaling factor);
when the scaling factor value is greater than or equal to 0, performing the following processes:
determining a first weight based on the scaling factor value;
determining a second weight based on the scaling factor value;
calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight;
obtaining a modified predicted sample value according to the additional value and the predicted sample value(in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value)
(in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

5. An aspect of the method according to aspect 4, wherein the method further comprises: when the scaling factor value is less than 0, output the predicted sample value.

6. An aspect of a method for intra predicting process of a video (or picture, frame) block (a block may be a current coding block or a subpartition of the current coding block), the method comprising:

obtaining a predicted sample value for a sample of the current coding block (in an example, the predicted sample value is obtained from one or more reference sample values, by using an intra prediction mode which is selected from one of a DC intra-prediction mode, a planar intra prediction mode, and an angular intra-prediction mode);
obtaining a scaling factor value according to an intra prediction mode for the current coding block, and according to a height of the current coding block or a width of the current coding block (this process is for angular mode. And when the intra prediction mode for the current coding block is not a horizontal mode and is not a vertical mode, the scaling factor value is obtained according to a height of the block or a width of the block for DC mode, planar mode, horizontal and vertical angular modes) (in an example, both of the height and the width are used to obtain the scaling factor);
when the intra prediction mode for the current coding block is angular mode (but the intra prediction mode for the current coding block is not a horizontal mode and is not a vertical mode), and when the scaling factor value is less than 0, output the predicted sample value;
otherwise (the intra prediction mode for the current coding block is not angular mode, or the intra prediction mode for the current coding block is a horizontal mode, or the intra prediction mode for the current coding block is a vertical mode, or the scaling factor value is greater than or equal to 0), performing the following processes:
determining a first weight based on the scaling factor value,
determining a second weight based on the scaling factor value,
calculating an additional value as a weighted sum of a top reference sample value and a left reference sample value, by weighting the top reference sample value with the first weight and the left reference sample value with the second weight,
obtaining a modified predicted sample value according to the additional value and the predicted sample value(in some embodiments, the predicted sample value is processed by using a sample weighting factor to obtain a weighted predicted value, the modified predicted sample value is obtained according to the additional value and the weighted predicted sample value)
(in an example, the method further comprises: normalizing the modified predicted sample value, by an arithmetic right shift of an integer representation of the modified predicted sample value, resulting in a normalized modified predicted sample value).

7. An aspect of the method according to any one of aspects 4 to 6, wherein the height of the current coding block is equal to a value of refH−nTbH, the variable refH indicates a height of reference samples, and the variable nTbH indicates a height of a transform block (or the block).

8. An aspect of the method according to any one of aspects 4 to 7, wherein the width of the current coding block is equal to a value of refW−nTbW, the variable refW indicates a width of reference samples, and the variable nTbW indicates a width of a transform block (or the block).

9. An aspect of an encoder (20) comprising processing circuitry for carrying out the method according to any one of aspects 1 to 8.

10. An aspect of a decoder (30) comprising processing circuitry for carrying out the method according to any one of aspects 1 to 8.

11. An aspect of a computer program product comprising program code for performing the method according to any one of the preceding aspects when executed on a computer or a processor.

12. An aspect of a decoder, comprising:

one or more processors; and
a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the decoder to carry out the method according to any one of the preceding aspects.

13. An aspect of an encoder, comprising:

one or more processors; and
a non-transitory computer-readable storage medium coupled to the processors and storing programming for execution by the processors, wherein the programming, when executed by the processors, configures the encoder to carry out the method according to any one of the preceding aspects.

14. An aspect of a non-transitory computer-readable medium carrying a program code which, when executed by a computer device, causes the computer device to perform the method of any one of the preceding aspects.