Incremental Transform Set Construction for Video Coding

Solution Overview

Problem

Existing video coding standards face inefficiencies due to the use of a single block transform, which assumes uniform statistical properties across all residual blocks, whereas actual video content and prediction modes result in diverse statistical characteristics.

Innovation Solution

The proposed solution involves incremental transform set construction, where multiple transform sets are built by recursively adding transform candidates to previously constructed sets, allowing for adaptivity to diverse block signal characteristics and reducing signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple transform candidates are supported to adapt to diverse residual block characteristics, then compression efficiency is improved, but signaling overhead and implementation complexity increase

Engineering Contradiction:

Improvecompression efficiencyVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments transform candidates into multiple transform sets (first transform set, second transform set, third transform set) with different numbers of candidates. This allows the encoder to select appropriate transform sets based on residual block characteristics, providing adaptability while controlling signaling overhead by not always transmitting the full set of candidates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by allowing transform skip mode where no transform is applied, and by providing transform sets with varying numbers of candidates (some sets have fewer candidates than others). This enables the system to use only the necessary number of transform candidates for each specific residual block, avoiding excessive signaling when full transform sets are not needed.

Inventive Principle:

Principle #16Partial or excessive action

2Productivity

If multiple transform candidates are supported to adapt to diverse residual block characteristics, then compression efficiency is improved, but implementation complexity increases

Engineering Contradiction:

Improvecompression efficiencyVSAvoidimplementation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments transform candidates into multiple transform sets (first transform set, second transform set, third transform set) with different numbers of candidates. This allows the encoder to select appropriate transform sets based on residual block characteristics, providing adaptability while controlling signaling overhead by not always transmitting the full set of candidates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic transform set selection where the choice of transform set (first, second, or third) is made adaptively based on residual block characteristics. The system dynamically adjusts which transform sets are applied to different residual blocks, enabling flexible adaptation to diverse video content while managing complexity through structured selection criteria.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If a single block transform is used, then implementation is simple, but compression efficiency deteriorates due to inability to adapt to diverse statistical characteristics

Engineering Contradiction:

Improveimplementation simplicityVSAvoidcompression efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent segments transform candidates into multiple transform sets (first transform set, second transform set, third transform set) with different numbers of candidates. This allows the encoder to select appropriate transform sets based on residual block characteristics, providing adaptability while controlling signaling overhead by not always transmitting the full set of candidates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by allowing different transform sets to be applied to different residual blocks based on their specific characteristics. Instead of using a single transform for all blocks, the system selects transforms locally adapted to each residual block's statistical properties, improving compression efficiency while maintaining manageable complexity through structured selection.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12267496B2Incremental transform set construction and transform signaling for video coding

Publication Date: 2025.04.01 APPLE INC

AI summary

Video coders and decoders perform transform coding and decoding on blocks of video content according to an adaptively selected transform type. The transform types are organized into a hierarchy of transform sets where each transform set includes a respective number of transforms and each higher-level transform set includes the transforms of each lower-level transform set within the hierarchy. The video coders and video decoders may exchange signaling that establishes a transform set context from which a transform set that was selected for coding given block(s) may be identified. The video coders and video decoders may exchange signaling that establishes a transform decoding context from which a transform that was selected from the identified transform set to be used for decoding the transform unit. The block(s) may be coded and decoded by the selected transform.