Unified Transform Type Signaling for Adaptive Coefficient Coding
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Solution Overview
Problem
Current video coding technologies, such as VVC, lack the ability to efficiently signal transform types and adapt level coding techniques based on the selected transform type, leading to suboptimal compression efficiency.
Innovation Solution
Unify transform type signaling and implement transform type-dependent level coding techniques, allowing for the selection of transformations from a list that includes an identity transformation and non-identity transformations, and adapt decoding processes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transform type signaling is unified and level coding is adapted based on transform type, then compression efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by adapting level coding techniques based on the selected transform type. Different coding strategies are employed for different transform types (e.g., DST vs DCT), optimizing the coding parameters to match the transform characteristics and thereby improving compression efficiency.
Solution Approach 2:
The patent implements a unified transform type signaling mechanism that works across multiple transform types and block sizes. The signaling framework is designed to be universal, handling both 2D and 1D transforms, and various transform types (DST, DCT, identity) through a common interface, reducing the need for separate signaling paths.
2Measurement precision
If multiple transform types are supported with adaptive level coding, then reconstruction accuracy is improved, but processing time increases
Solution Approach 1:
The patent employs dynamic selection of level coding techniques based on the transform type. The coding approach is not static but adapts dynamically to the chosen transform, allowing the system to optimize reconstruction accuracy for each transform type while managing processing requirements through conditional logic.
3Adaptability or versatility
If transform skip mode is enabled for all block sizes, then flexibility is improved, but bitstream complexity increases
Solution Approach 1:
The patent extends transform skip mode availability to all transform block sizes through a universal signaling mechanism. The same syntax elements and coding structures are used regardless of block size, providing flexibility while maintaining consistent bitstream complexity through the unified framework.
Data Source
AI summary
A picture in a data stream is subdivided into different size transform bocks. For a transform block, a transformation is selected by checking whether the block's size exceeds a threshold. If it does, a default technique is used to select the transformation. If it does not, a transformation is used from a list of transformations as identified by an index, the list including an identity transformation and non-identity transformations. A coefficients block in the data stream is decoded, and if the selected transformation is the identity transformation, then the coefficients block is used as a residual sample array, and if the selected transformation is not the identity transformation, the coefficients block is subjected to an inverse transformation corresponding to the selected transformation to obtain a residual sample array used to correct a prediction for the transform block.