Video Transform Block Encoding With Size-Gated Secondary Transform
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Solution Overview
Problem
The increasing complexity of processing high spatial resolution, high frame rate video content requires a more efficient transform technology to reduce computational complexity and memory requirements.
Innovation Solution
A method and apparatus for encoding and decoding video signals that selectively apply a non-separable secondary transform based on the size of the transform block, omitting it for blocks smaller than or equal to 4×4 and applying it to larger blocks, using transforms like DCT-2, DST-7, and DST-8, and Givens rotation-based transforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a non-separable secondary transform is applied to all transform blocks to improve compression efficiency, then the transformation quality improves, but the computational complexity increases
Solution Approach 1:
The patent applies different transform strategies to different regions of the transform block based on local characteristics. Specifically, the non-separable secondary transform is applied only to certain regions (e.g., when block size exceeds 4×4 or based on gradient conditions) rather than uniformly across the entire block, optimizing the balance between quality and complexity locally.
Solution Approach 2:
The patent dynamically changes transform parameters based on block characteristics. The decision to apply the non-separable secondary transform depends on parameters such as block size (greater than 4×4), gradient conditions, and other local features, allowing the system to adapt the transformation complexity to the actual content requirements.
2Productivity
If transform processing is performed on all video blocks to improve compression ratio, then the compression efficiency improves, but the processing time increases
Solution Approach 1:
The patent applies the computationally intensive non-separable secondary transform only partially - specifically to transform blocks that meet certain criteria (size greater than 4×4, specific gradient conditions) rather than to all blocks. This selective application reduces overall processing time while maintaining compression efficiency where it is most beneficial.
Solution Approach 2:
The patent skips the non-separable secondary transform for small blocks (4×4 and below) and for blocks that don't meet specific conditions, rushing through these cases with simpler processing. This allows the system to focus computational resources on blocks where the transform provides the most value, reducing total processing time.
Data Source
AI summary
A video signal encoding method according to an embodiment of the present invention comprises checking a transform block including residual samples except a prediction sample from a picture of the video signal, generating transform coefficients through a transform for the residual samples of the transform block based on a size of the transform block, and performing quantization and entropy coding the transform coefficients, wherein generating the transform coefficients includes, applying a forward primary transform to each of a horizontal direction and vertical direction of the transform block including the residual samples, and not applying a forward non-separable secondary transform to the transform block to which the primary transform has been applied when the size of the transform block is smaller than or equal to 4×4, and applying the forward non-separable secondary transform to the transform block when the size of the transform block is greater than 4×4.