Partitioned Secondary Transforms for Lower-Complexity Video Coding
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Solution Overview
Problem
Next-generation video content with high spatial resolution, high frame rate, and high dimensionality requires more efficient transform designs to manage increased memory storage, memory access rate, and processing power, particularly in terms of coding efficiency and complexity.
Innovation Solution
A method is provided for partitioning a transform coefficient block into 4×4 blocks and applying individual secondary transforms, with the option to share these transforms between blocks, and conditionally applying them based on the number of non-zero coefficients, allowing for flexible transform selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transform is applied to high-resolution video content, then coding efficiency is improved, but computational complexity increases
Solution Approach 1:
The transform coefficient block is divided into multiple 4×4 sub-blocks, and the secondary transform is applied independently to each sub-block. This segmentation allows the transform to be processed in smaller units, reducing the computational burden per block while maintaining overall coding efficiency through localized optimization
Solution Approach 2:
Different secondary transforms are applied to different 4×4 sub-blocks based on local characteristics such as the number of non-zero coefficients. This local adaptation allows the system to optimize coding efficiency for each region while avoiding unnecessary computations in regions where simpler processing suffices
2Productivity
If individual secondary transforms are applied to each partitioned block, then coding efficiency is enhanced, but device complexity increases
Solution Approach 1:
The system dynamically selects and applies different secondary transform types based on parameters such as the number of non-zero coefficients in each 4×4 block. By changing transform parameters adaptively rather than applying a fixed transform everywhere, coding efficiency is enhanced while avoiding the complexity of always using the most sophisticated transform
3Productivity
If secondary transform is applied to all divided blocks, then coding performance is improved, but processing complexity increases
Solution Approach 1:
The secondary transform is applied selectively to only those 4×4 blocks that meet certain criteria (e.g., having sufficient non-zero coefficients), rather than applying it uniformly to all blocks. This partial application maintains coding performance for blocks that benefit from the transform while avoiding unnecessary processing complexity for blocks where the transform would provide minimal benefit
Data Source
AI summary
Techniques and systems for reconstructing a video signal, which include: obtaining a transform coefficient block by performing an entropy decoding and a dequantization for a current block; deriving a secondary transform corresponding to a specific area in the transform coefficient block, wherein the specific area represents an area including a top-left block of the transform coefficient block; performing an inverse secondary transform for each of subblocks within the specific area using the secondary transform; performing an inverse primary transform for a block which the inverse secondary transform is applied to; and reconstructing the current block using a block which the primary inverse transform is applied to.