Video Decoder LFNST Selection Directly From CCLM Parameters

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Solution Overview

Problem

The existing low-frequency non-separable transform (LFNST) technology in H.266/VVC has poor applicability to the cross-component linear model (CCLM) mode, complicating the transform process and reducing encoding efficiency due to the need for additional mapping of CCLM modes to traditional intra prediction modes.

Innovation Solution

A transform method that determines the LFNST transform kernel directly from the CCLM parameter without mapping to traditional intra prediction modes, simplifying the transform process and improving encoding efficiency by allowing flexible selection of the LFNST transform kernel based on CCLM parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If CCLM mode is mapped to traditional intra prediction mode for LFNST selection, then LFNST can be applied to CCLM mode, but the transform process becomes complicated and encoding efficiency decreases

Engineering Contradiction:

Improveapplicability of LFNST to CCLM modeVSAvoidtransform process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter basis for LFNST transform kernel selection from traditional intra prediction mode to CCLM mode parameters. By using CCLM mode parameters (such as cb_pred_mode and cr_pred_mode) directly to determine the transform kernel, the patent eliminates the need for mode mapping while maintaining adaptability of LFNST to CCLM mode.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If CCLM mode is mapped to traditional intra prediction mode for LFNST selection, then LFNST can be applied to CCLM mode, but encoding efficiency decreases

Engineering Contradiction:

Improveapplicability of LFNST to CCLM modeVSAvoidencoding efficiency

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If additional mapping is performed for CCLM mode, then LFNST can be applied to CCLM mode, but the transform process is complicated

Engineering Contradiction:

Improveapplicability of LFNST to CCLM modeVSAvoidtransform process simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent changes the parameter basis for LFNST transform kernel selection from traditional intra prediction mode to CCLM mode parameters. By using CCLM mode parameters (such as cb_pred_mode and cr_pred_solve) directly to determine the transform kernel, the patent eliminates the need for mode mapping while maintaining adaptability of LFNST to CCLM mode.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250211730A1Transform method and decoder

Publication Date: 2025.06.26 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

A transform method and a decoder. The encoder determines a prediction mode parameter of a current block; determines a cross-component linear model (CCLM) parameter when the prediction mode parameter indicates that CCLM prediction is used for the current block to determine an intra prediction value; determines the intra prediction value of the current block according to the CCLM parameter, and calculates a residual value between the current block and the intra prediction value; determines a low-frequency non-separable transform (LFNST) transform kernel used for the current block according to the CCLM parameter, sets an LFNST index, and signals the LFNST index into a bitstream of a video, when LFNST is used for the current block; and transforms the residual value with the LFNST transform kernel.