Sign Bit Hiding in Video Transform Units
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Solution Overview
Problem
Current video encoding standards, such as H.264/AVC and developing MPEG-H, face challenges in efficiently encoding and decoding residual video data due to the high percentage of data occupied by sign bits of non-zero coefficients in transform units.
Innovation Solution
The proposed solution involves using sign bit hiding techniques, specifically by employing multi-level significance maps and parity-based methods to hide sign bits for subsets of coefficients within transform units, thereby reducing the overhead of sign bit encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sign bits are encoded for each non-zero coefficient in transform units, then the precision of coefficient representation is maintained, but the bitstream size increases significantly
Solution Approach 1:
The patent extracts and removes the sign bit information from the conventional encoding process. Instead of encoding each sign bit separately, the invention uses the sign information to adjust the magnitude of coefficients, thereby eliminating the need for dedicated sign bit encoding and reducing bitstream size while preserving coefficient precision
Solution Approach 2:
The patent merges the sign bit encoding function with the magnitude encoding process. By incorporating sign information into the coefficient magnitude representation, the invention combines two separate encoding tasks into one, reducing overall bitstream overhead while maintaining full coefficient precision
2Quantity of substance
If sign bit hiding is applied to reduce bitstream size, then the quantity of data is reduced, but the complexity of encoding and decoding processes increases
Solution Approach 1:
The patent changes the parameter representation by modifying coefficient magnitudes based on sign information rather than storing separate sign bits. This parameter transformation simplifies the overall encoding structure by eliminating dedicated sign bit handling while maintaining coefficient accuracy
Solution Approach 2:
The encoding process automatically determines and applies sign information to coefficient magnitudes without requiring separate sign bit encoding steps. The system serves itself by integrating sign handling into the magnitude encoding process, reducing operational complexity despite the innovative approach
3Productivity
If multi-level significance maps are used to organize coefficients, then the efficiency of sign bit hiding is improved, but the device complexity increases
Solution Approach 1:
The patent segments the transform unit into multiple significance levels, organizing coefficients hierarchically. This segmentation enables more efficient sign bit hiding by allowing different encoding strategies for different coefficient groups, improving overall compression efficiency while managing complexity through structured organization
Data Source
AI summary
Methods of encoding and decoding for video data are described for encoding or decoding coefficients for a transform unit. In particular, the sign bits for the non-zero coefficients are encoded using sign bit hiding. Two or more sets of coefficients are defined for the transform unit and a sign bit may be hidden for each set, subject to satisfaction of a threshold test. The sets may correspond to coefficient groups that are otherwise used in multi-level significance map encoding and decoding.