Unified NSST Binarization for Video Decoding
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Solution Overview
Problem
Current video coding standards, such as the JVET test model, face inefficiencies in bitstream compression and coding complexity due to the handling of non-separable secondary transform (NSST) indices, particularly in intra prediction modes and block sizes, which affects bitrate and coding performance.
Innovation Solution
The proposed techniques unify binarization of NSST syntax elements, applying truncated unary binarization based on intra modes and block sizes, and context modeling for entropy coding, allowing for reduced redundancy and improved compression efficiency by eliminating unnecessary signaling of NSST indices when the PDPC index is non-zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate binarization methods are used for different NSST index ranges, then coding precision is improved, but device complexity increases
Solution Approach 1:
The patent applies a unified binarization method for all NSST index values regardless of their range. Instead of using different binarization schemes for different index ranges (which would increase complexity), the invention consistently applies the same binarization approach, simplifying the decoding process while maintaining adequate coding precision through the unified scheme.
2Measurement precision
If NSST index signaling is performed for all blocks, then measurement precision is improved, but loss of information increases due to redundancy
Solution Approach 1:
The patent extracts and removes redundant NSST index signaling from the bitstream. By identifying blocks where NSST indexing is unnecessary (such as when PDPC index is non-zero or for certain block sizes and prediction modes), the invention eliminates the transmission of redundant index information, reducing bitstream redundancy while preserving necessary precision for blocks that require it.
3Manufacturing precision
If multiple binarization schemes are implemented, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent implements a universal binarization scheme that handles all NSST index cases through a single method. This unified approach serves multiple functions: it works for all block sizes, all prediction modes, and all index ranges, eliminating the need to implement and manage multiple separate binarization schemes while maintaining coding precision.
4Reliability
If NSST index is always signaled, then reliability is improved, but productivity decreases due to increased bitrate
Solution Approach 1:
The patent applies partial signaling of NSST indices by determining the appropriate action based on specific conditions. Instead of always signaling the index (excessive action) or never signaling it (insufficient action), the invention selectively signals indices only when necessary based on block size, prediction mode, and other factors, achieving optimal balance between reliability and compression efficiency.
Data Source
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AI summary
An example device for decoding video data includes a memory configured to store video data and one or more processors implemented in circuitry and configured to determine a maximum possible value for a secondary transform syntax element for a block of video data, entropy decode a value for the secondary transform syntax element of the block to form a binarized value representative of the secondary transform for the block, reverse binarize the value for the secondary transform syntax element using a common binarization scheme regardless of the maximum possible value to determine the secondary transform for the block, and inverse-transform transform coefficients of the block using the determined secondary transform.