EP-4736407-A1 - BLOCK LEVEL ADAPTIVE WEIGHTED PREDICTION

Abstract

This disclosure relates generally to video coding/decoding and particularly for improving block level adaptive weighted prediction. One method includes receiving the coded video bitstream comprising the current block of the current frame and a syntax element indicating a prediction mode for the current block, a plurality of scaling factor look-up tables being stored; determining the prediction mode based on a value of the syntax element, the prediction mode being used for predicting the current block based on a reference block of a reference frame; selecting a scaling factor look-up table from the plurality of scaling factor look-up tables based on an inter prediction mode of the current block or a picture order count (POC) distance between the reference frame and the current frame; determining a scaling factor from the selected scaling factor look-up table; and reconstructing the current block based on the reference block and the determined scaling factor.

Inventors

• ZHAO, LIANG
• ZHAO, XIN
• YE, JING
• GAO, Han
• LIU, SHAN

Assignees

• Tencent America LLC

Dates

Publication Date

20260506

Application Date

20230914

Claims (17)

1. 1. A method for decoding a current block of a current frame in a coded video bitstream, the method comprising: receiving, by a decoding device comprising a memory storing instructions and a processor in communication with the memory, the coded video bitstream comprising the current block of the current frame and a syntax element indicating a prediction mode for the current block, the memory of the decoding device storing a plurality of scaling factor look-up tables; determining, by the decoding device based on the coded video bitstream, the prediction mode based on a value of the syntax element, the prediction mode being used for predicting the current block based on a reference block of a reference frame; selecting, by the decoding device, a scaling factor look-up table from the plurality of scaling factor look-up tables based on at least one of the following: an inter prediction mode of the current block or a picture order count (POC) distance between the reference frame and the current frame, wherein a size of each of the plurality of scaling factor look-up tables is less than a predetermined threshold size; determining, by the decoding device, a scaling factor from the selected scaling factor look-up table; and reconstructing, by the decoding device, the current block based on the reference block and the determined scaling factor.
2. 2 The method according to claim 1, wherein the selecting the scaling factor look-up table from the plurality of scaling factor look-up tables comprises: in response to the inter prediction mode of the current block being a NEARMV mode, selecting a first look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; in response to the inter prediction mode of the current block being an AMVDNEWMV mode, selecting a second look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; or in response to the inter prediction mode of the current block being a NEWMV mode, selecting a third look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table.
3. 3 The method according to claim 2, wherein: scaling factors in the first look-up table have smaller absolute value than a threshold; scaling factors in the second look-up table have larger absolute value than the threshold; and scaling factors in the third look-up table have larger absolute value than the threshold, wherein the threshold is a pre-defined threshold or a derived threshold.
4. 4. The method according to claim 1, wherein the selecting the scaling factor look-up table from the plurality of scaling factor look-up tables comprises: in response to the POC distance being smaller than a threshold, selecting a first look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; or in response to the POC distance being larger than the threshold, selecting a second look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table.
5. 5. The method according to claim 1, wherein the selecting the scaling factor look-up table from the plurality of scaling factor look-up tables comprises: in response to the inter prediction mode of the current block being a NEARMV mode and the POC distance being smaller than a threshold, selecting a first look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; in response to the inter prediction mode of the current block being an AMVDNEWMV mode and the POC distance being smaller than the threshold, selecting a second look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; in response to the inter prediction mode of the current block being a NEWMV mode and the POC distance being smaller than the threshold, selecting a third look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; in response to the inter prediction mode of the current block being the NEARMV mode and the POC distance being larger than a threshold, selecting a fourth look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; in response to the inter prediction mode of the current block being the AMVDNEWMV mode and the POC distance being larger than the threshold, selecting a fifth look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table; or in response to the inter prediction mode of the current block being the NEWMV mode and the POC distance being larger than the threshold, selecting a sixth look-up table of the plurality of scaling factor look-up tables as the scaling factor look-up table.
6. 6 The method according to claim 1, wherein: the plurality of scaling factor look-up tables comprises a same number of scaling factors.
7. 7 The method according to claim 1, wherein the determining, based on the coded video bitstream, the prediction mode for predicting the current block based on the reference block of the reference frame comprises: in response to the inter prediction mode of the current block being a NEARMV mode or a NEWMV mode, extracting a flag from the coded video bitstream, wherein the flag indicates the prediction mode for predicting the current block based on the reference block of the reference frame.
8. 8 The method according to claim 7, wherein: in response to the inter prediction mode of the current block being an AMVDNEWMV mode, the flag is disabled.
9. 9. The method according to claim 1, further comprising: in response to the POC distance being larger than or equal to a threshold, adding an offset to the scaling factor or multiplying a factor to the scaling factor.
10. 10. The method according to claim 1, further comprising: determining the reference block of the reference frame based on a motion vector.
11. 11. The method according to claim 1, wherein the reconstructing the current block based on the reference block and the determined scaling factor according to the linear equation comprises: computing pixel values of the current block as a*p+b, wherein a is the determined scaling factor, b is a determined offset, and p is a reference pixel value at a reference point determined by a motion vector.
12. 12. A method for decoding a current block of a current frame in a coded video bitstream, the method comprising: receiving, by a device comprising a memory storing instructions and a processor in communication with the memory, the coded video bitstream; determining, by the device based on the coded video bitstream, a prediction mode for predicting the current block based on a reference block of a reference frame; determining, by the device based on the coded video bitstream, a scaling factor for luma or chroma components of the current block; and reconstructing, by the device, the current block based on the reference block and the determined scaling factor according to a linear equation.
13. 13. The method according to claim 12, wherein: signaling of the scaling factor for the chroma component is based on signaling of the scaling factor for the luma component.
14. 14. The method according to claim 12, wherein: in response to a luma flag being signaled for the luma component, a chroma flag for the chroma component is signaled; or in response to a luma flag not being signaled for the luma component, a chroma flag for the chroma component is not signaled.
15. 15. The method according to claim 14, wherein: in response to a luma flag being signaled for the luma component and a chroma flag for the chroma component being signaled, the scaling factor for the luma component is used as the scaling factor for the chroma component.
16. 16. An apparatus for decoding a current block of a current frame in a coded video bitstream, the apparatus comprising: a memory storing instructions; and a processor in communication with the memory, wherein, when the processor executes the instructions, the processor is configured to cause the apparatus to perform the method in any of claims 1 to 15.
17. 17. A non-transitory computer readable storage medium storing instructions, wherein, when the instructions are executed by a processor, the instructions are configured to cause the processor to perform the method in any of claims 1 to 15.

Description

BLOCK LEVEL ADAPTIVE WEIGHTED PREDICTION INCORPORATION BY REFERENCE [0001] This application is based on and claims the benefit of priority to U.S. Provisional Application No. 63/524,545, filed on June 30, 2023, which is herein incorporated by reference in its entirety. This application is also based on and claims the benefit of priority to U.S. non-Provisional Patent Application No. 18/461,666, filed on September 6, 2023, which is herein incorporated by reference in its entirety. TECHNICAL FIELD [0002] This disclosure describes a set of advanced video/streaming coding/decoding technologies. More specifically, the disclosed technology involves improvement on block level adaptive weighted prediction (BAWP) to compensate local illumination variation. BACKGROUND [0003] Uncompressed digital video can include a series of pictures, and may specific bitrate requirements for storage, data processing, and for transmission bandwidth in streaming applications. One purpose of video coding and decoding can be the reduction of redundancy in the uncompressed input video signal, through various compression techniques. SUMMARY [0004] The present disclosure describes various embodiments of methods, apparatus, and computer- readable storage medium for improving block level adaptive weighted prediction (BAWP) to model local illumination compensation (LIC). According to one aspect, an embodiment of the present disclosure provides a method for decoding a current block of a current frame in a coded video bitstream. The method includes receiving, by a decoding device, a coded video bitstream comprising the current block of the current frame and a syntax element indicating a prediction mode for the current block. The device includes a memory storing instructions and a processor in communication with the memory, the memory also stores a plurality of scaling factor look-up tables. The method also includes determining, by the decoding device based on the coded video bitstream, the prediction mode based on a value of the syntax element, the prediction mode being used for predicting the current block based on a reference block of a reference frame; selecting, by the decoding device, a scaling factor look-up table from the plurality of scaling factor look-up tables based on at least one of the following: an inter prediction mode of the current block or a picture order count (POC) distance between the reference frame and the current frame, wherein a size of each of the plurality of scaling factor look-up tables is less than a predetermined threshold size; determining, by the decoding device, a scaling factor from the selected scaling factor look-up table; and reconstructing, by the decoding device, the current block based on the reference block and the determined scaling factor. According to one aspect, an embodiment of the present disclosure provides a method for decoding a current block of a current frame in a coded video bitstream. The method includes receiving, by a device, a coded video bitstream. The device includes a memory storing instructions and a processor in communication with the memory. The method also includes determining, by the device based on the coded video bitstream, a prediction mode for predicting the current block based on a reference block of a reference frame; determining, by the device based on the coded video bitstream, a scaling factor for luma or chroma components of the current block; and reconstructing, by the device, the current block based on the reference block and the determined scaling factor according to a linear equation. [0005] According to another aspect, an embodiment of the present disclosure provides an apparatus for processing a current block of a current frame in a coded video bitstream. The apparatus includes a memory storing instructions; and a processor in communication with the memory. When the processor executes the instructions, the processor is configured to cause the apparatus to perform the above methods for video decoding and/or encoding. [0006] In another aspect, an embodiment of the present disclosure provides non-transitory computer- readable mediums storing instructions which when executed by a computer for video decoding and/or encoding cause the computer to perform the above methods for video decoding and/or encoding. [0007] The above and other aspects and their implementations are described in greater detail in the drawings, the descriptions, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS [0008] Further features, the nature, and various advantages of the disclosed subject matter will be more apparent from the following detailed description and the accompanying drawings in which: [0009] FIG. 1 shows a schematic illustration of a simplified block diagram of a communication system (100) in accordance with an example embodiment; [0010] FIG. 2 shows a schematic illustration of a simplified block diagram of a communication system (200) in accordance with an example embodiment; [0