Predictive Coefficient Coding for Transform Skip Mode Efficiency
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Solution Overview
Problem
Existing video coding techniques are inefficient for coding residual blocks with few zero coefficients, as they assume a large number of transform coefficients are zero or one, leading to suboptimal performance in transform skip mode.
Innovation Solution
The proposed solution involves predictive coefficient coding, where coefficients are copied from neighboring coefficients or selected from a predefined list, improving coding efficiency for residual blocks with few zero coefficients by determining a predictive block and adding it to the residual block to reconstruct the current block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional transform coding techniques are used for residual blocks, then coding efficiency is improved when many coefficients are zero or one, but coding efficiency deteriorates for residual blocks with few zero coefficients (transform skip mode)
Solution Approach 1:
The patent implements dynamic adaptation of coefficient coding methods based on the characteristics of each residual block. When transform skip mode is detected or when few zero coefficients are present, the system switches from conventional transform coding to predictive coefficient coding, allowing the coding mechanism to adapt its behavior to match the actual data characteristics and maintain high coding efficiency across diverse block types
Solution Approach 2:
The patent changes the coding parameters and methodology based on the residual block characteristics. For blocks with few zero coefficients, it employs predictive coefficient coding with neighboring coefficient copying and predefined lists, whereas for traditional blocks it uses conventional transform coding, thus optimizing the parameter selection according to the specific coding scenario
2Quantity of substance
If transform coding is applied to residual blocks, then compression is achieved when coefficients are zero or one, but distortion and artifacts increase for non-transformed blocks with few zero coefficients
Solution Approach 1:
The patent uses copying of neighboring coefficients to predict current block coefficients, eliminating the need for transform coding in blocks with few zero coefficients. By copying from already-decoded neighboring blocks, the method preserves original coefficient values without transform-induced distortion while maintaining compression through redundancy exploitation
Solution Approach 2:
The patent introduces predefined lists of coefficient values as intermediaries between the source and destination blocks. These lists serve as a reference database that mediates the copying process, allowing selection of appropriate coefficient values that reduce artifacts while maintaining compression efficiency for transform skip mode blocks
3Device complexity
If conventional coefficient coding is used, then simplicity is maintained, but coding performance deteriorates for screen content and transform skip mode
Solution Approach 1:
The patent segments the coefficient coding process into distinct pathways: conventional transform coding for traditional blocks and predictive coefficient coding for transform skip mode blocks. This segmentation allows each pathway to be optimized independently, maintaining simplicity where applicable while enhancing performance where needed without requiring complete system redesign
Solution Approach 2:
The patent creates a universal coefficient coding framework that can handle both conventional transform blocks and transform skip mode blocks through a single integrated system. The framework uses mode detection and adaptive selection to apply the appropriate coding method, making the system multi-functional without requiring separate independent coding systems
Data Source
AI summary
A video decoder configured to determine a residual block by, for a first coefficient of a coefficient group, receiving a first instance of a flag, wherein the first instance of the flag is set to a first value; in response to the first instance of the flag being set to the first value, copying a coefficient value of a neighboring coefficient for the first coefficient; for a second coefficient of the coefficient group, receiving a second instance of the flag, wherein the second instance of the flag is set to a second value; in response to the second instance of the flag being set to the second value, receiving an index; determining, from a list of coefficient values, a value corresponding to the index; and set a value for the second coefficient to the value corresponding to the index.