US-20260129192-A1 - DECODER, ENCODER, AND METHOD FOR TRANSMITTING BITSTREAM

US20260129192A1US 20260129192 A1US20260129192 A1US 20260129192A1US-20260129192-A1

Abstract

A decoder includes a memory storing a computer program and a processor configured to invoke and run the computer program to perform the following. A first intra prediction mode and a second intra prediction mode for the current block are determined according to amplitude values of N intra prediction modes. A weighted blending condition for the current block is determined according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode. A target prediction value of the current block is determined according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode.

Inventors

Zhihuang XIE

Assignees

GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP., LTD.

Dates

Publication Date: 20260507
Application Date: 20260105

Claims (20)

1 . A video decoder, comprising: a memory configured to store a computer program; and a processor configured to execute the computer program stored in the memory to: decode a bitstream to determine amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block, and determining a first intra prediction mode and a second intra prediction mode for the current block according to the amplitude values of the N intra prediction modes, N being an integer greater than 1; determine a weighted blending condition for the current block according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode; and determine a target prediction value of the current block according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode.
2 . The decoder of claim 1 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: decoding the bitstream to obtain a first flag, wherein the first flag indicates whether a first technology is used, and the first technology is used for the first image content; and determining, when the first flag indicates that the first technology is used, the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode.
3 . The decoder of claim 1 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: determining the weighted blending condition for the current block as that a ratio of a first amplitude value of the first intra prediction mode to a second amplitude value of the second intra prediction mode is less than or equal to a first preset threshold.
4 . The decoder of claim 3 , wherein determining the target prediction value of the current block according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or the third intra prediction mode comprises: determining the target prediction value of the current block by using the first intra prediction mode, when the ratio of the first amplitude value to the second amplitude value is greater than the first preset threshold.
5 . The decoder of claim 1 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: determining, when the first intra prediction mode and the second intra prediction mode satisfy a first preset condition, the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode.
6 . The decoder of claim 5 , wherein the processor is further configured to execute the computer program stored in the memory to: determine, when the first intra prediction mode and the second intra prediction mode do not satisfy the first preset condition, the target prediction value of the current block by using the first intra prediction mode.
7 . The decoder of claim 5 , wherein the first preset condition is that: neither the first intra prediction mode nor the second intra prediction mode is a Planar mode or a DC mode, and the second amplitude value of the second intra prediction mode is not zero.
8 . The decoder of claim 1 , wherein determining the amplitude values of the N intra prediction modes corresponding to the reconstructed region adjacent to the current block comprises: decoding the bitstream to obtain a decoder-side intra mode derivation (DIMD) enable flag, the DIMD enable flag indicating whether a DIMD technology is used for the current block; and determining the amplitude values of the N intra prediction modes corresponding to the reconstructed region adjacent to the current block when the DIMD enable flag indicates that the DIMD technology is used for the current block.
9 . The decoder of claim 8 , wherein determining the amplitude values of the N intra prediction modes corresponding to the reconstructed region adjacent to the current block when the DIMD enable flag indicates that the DIMD technology is used for the current block comprises: determining amplitude values of N intra prediction modes corresponding to a template region of the current block when the DIMD enable flag indicates that the DIMD technology is used for the current block.
10 . The decoder of claim 1 , wherein determining the first intra prediction mode and the second intra prediction mode of the current block according to the amplitude values of the N intra prediction modes comprises: determining an intra prediction mode with a greatest amplitude value among the N intra prediction modes as the first intra prediction mode; and determining an intra prediction mode with a second greatest amplitude value among the N intra prediction modes as the second intra prediction mode.
11 . The decoder of claim 1 , wherein the processor is further configured to execute the computer program stored in the memory to: decode the bitstream to obtain a second flag, the second flag indicating whether the target prediction value of the current block is determined according to at least one of the first intra prediction mode, the second intra prediction mode, or the third intra prediction mode; and determine the amplitude values of the N intra prediction modes corresponding to the reconstructed region adjacent to the current block when the second flag is true.
12 . The decoder of claim 11 , wherein the second flag is a decoder-side intra mode derivation (DIMD) enabled flag.
13 . The decoder of claim 2 , wherein the first flag is reused with a third flag of the current sequence, and the third flag is an intra-block copy (IBC) enable flag or a template matching prediction (TMP) enable flag of a sequence level.
14 . The decoder of claim 1 , wherein the third intra prediction mode is a Planar mode.
15 . An encoder, comprising: a memory configured to store a computer program; and a processor configured to execute the computer program stored in the memory to: determine amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block, and determining a first intra prediction mode and a second intra prediction mode for the current block according to the amplitude values of the N intra prediction modes, N being an integer greater than 1; determine a weighted blending condition for the current block according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode; determine an intermediate prediction value of the current block according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode; and determine a target prediction value of the current block according to the intermediate prediction value of the current block.
16 . The encoder of claim 15 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: determining, when an image content corresponding to the current block is a first image content, the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode; and wherein the processor is further configured to execute the computer program stored in the memory to: signal a first flag into a bitstream, wherein the first flag indicates whether a first technology is used, and the first technology is used for the first image content.
17 . The encoder of claim 15 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: determining the weighted blending condition for the current block as that a ratio of a first amplitude value of the first intra prediction mode to a second amplitude value of the second intra prediction mode is less than or equal to a first preset threshold.
18 . The encoder of claim 17 , wherein determining the intermediate prediction value of the current block according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or the third intra prediction mode comprises: determining the intermediate prediction value of the current block by using the first intra prediction mode when the ratio of the first amplitude value to the second amplitude value is greater than the first preset threshold.
19 . The encoder of claim 15 , wherein determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode comprises: determining the weighted blending condition for the current block according to the amplitude value of the first intra prediction mode and the amplitude value of the second intra prediction mode when the first intra prediction mode and the second intra prediction mode satisfy a first preset condition, wherein the first preset condition is that: neither the first intra prediction mode nor the second intra prediction mode is a Planar mode or a DC mode, and the second amplitude value corresponding to the second intra prediction mode is not zero.
20 . A method for transmitting a bitstream, comprising: generating the bitstream according to an encoding method; and transmitting the bitstream, wherein the encoding method comprises: decoding a bitstream to determine amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block, and determine a first intra prediction mode and a second intra prediction mode for the current block according to the amplitude values of the N intra prediction modes, N being an integer greater than 1; determining a weighted blending condition for the current block according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode; and determining a target prediction value of the current block according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a continuation of U.S. Non-provisional application Ser. No. 18/753,956, filed Jun. 25, 2024, which is a continuation of International Application No. PCT/CN2021/142114, filed Dec. 28, 2021, the entire disclosures of which are incorporated herein by reference. TECHNICAL FIELD This disclosure relates to the technical field of video coding, and in particular to a decoder, an encoder, and a method for transmitting a bitstream. BACKGROUND Digital video technology may be incorporated into multiple video apparatuses such as a digital television, a smart mobile phone, a computer, an e-reader, or a video player, etc. With the development of video technology, video data includes an enormous amount of data. To facilitate video data transmission, a video apparatus implements a video compression technology to enable more effective transmission or storage of the video data. Compression of the video is realized through encoding, where the encoding process includes prediction, transformation, and quantization, etc. For example, a prediction block of a current block is determined by intra prediction and/or inter prediction, the prediction block is subtracted from the current block to obtain a residual block, the residual block is transformed to obtain transform coefficients, and the transform coefficients are quantized to obtain quantization coefficients that are then encoded to form a bitstream. In order to improve accuracy of intra prediction, weighted blending prediction may be performed on the current block by using two or more intra prediction modes, so as to obtain a prediction value of the current block. In some cases, the weighted blending prediction can improve the prediction effect. However, in some cases, the weighted blending prediction may reduce the prediction quality. Therefore, before the weighted blending, it is necessary to determine whether to perform the weighted blending based on a weighted blending condition. As can be seen, the setting of the weighted blending condition directly influences the accuracy of intra prediction. SUMMARY In a first aspect, a decoder is provided in the present disclosure. The decoder includes a memory storing a computer program and a processor configured to invoke and run the computer program stored in the memory to perform the following. A bitstream is decoded to determine amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block, and a first intra prediction mode and a second intra prediction mode for the current block are determined according to the amplitude values of the N intra prediction modes, where Nis an integer greater than 1. A weighted blending condition for the current block is determined according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode. A target prediction value of the current block is determined according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode In a second aspect, an encoder is provided in the present disclosure. The encoder includes a memory storing a computer program and a processor configured to invoke and run the computer program stored in the memory to perform the following. Amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block are determined, and a first intra prediction mode and a second intra prediction mode for the current block are determined according to the amplitude values of the N intra prediction modes, where N is an integer greater than 1. A weighted blending condition for the current block is determined according to an amplitude value of the first intra prediction mode and an amplitude value of the second intra prediction mode. An intermediate prediction value of the current block is determined according to the weighted blending condition and at least one of the first intra prediction mode, the second intra prediction mode, or a third intra prediction mode. A target prediction value of the current block is determined according to the intermediate prediction value of the current block. In a third aspect, a method for transmitting a bitstream is provided. The method includes generating a bitstream according to an encoding method, and transmitting the bitstream. The encoding method includes the following. Amplitude values of N intra prediction modes corresponding to a reconstructed region adjacent to a current block are determined, and a first intra prediction mode and a second intra prediction mode for the current block are determined according to the amplitude values of the N intra prediction modes, where Nis an integer greater than 1. A weighted blending condition for the current block is determined according to an amplitude value of the first intra prediction mode and an amplitude