Secondary Transform Core Selection for Variable Video Block Sizes
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction and motion compensation, particularly in handling various block sizes and transform processes, leading to suboptimal compression ratios and increased data requirements.
Innovation Solution
Implementing a unified secondary transform process that includes determining a secondary transform core based on intra prediction modes and generating a primary transform coefficient block, which is then de-quantized and reconstructed, along with a secondary transform coefficient block to enhance compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional transform processes are used for various block sizes, then device complexity is reduced, but compression efficiency deteriorates
Solution Approach 1:
The patent implements dynamic selection of transform types (DST-II, DST-VII, DCT-II) based on intra prediction mode and block characteristics. The transform type is not fixed but adapts to the specific coding context, allowing the system to optimize compression efficiency for different block sizes and prediction modes while managing complexity through conditional logic rather than exhaustive processing
Solution Approach 2:
The patent changes transform parameters (transform type, block size) based on intra prediction mode and block characteristics. By selecting different transform types and sizes dynamically, the system optimizes the transformation process for each specific case, improving compression efficiency without requiring a single complex transform to handle all scenarios
2Loss of information
If transform coefficient blocks are reduced in size, then entropy coding efficiency is improved, but transform processing complexity increases
Solution Approach 1:
The patent segments the transform coefficient block into multiple smaller sub-blocks for independent processing. This segmentation allows entropy coding to operate more efficiently on smaller units with fewer non-zero coefficients, while the transform processing complexity is managed through the structured approach of dividing and conquering the larger block
3Productivity
If unified secondary transform is applied to various block sizes, then compression ratio is improved, but computational complexity increases
Solution Approach 1:
The patent applies different secondary transform types (DST-II, DST-VII) to different regions or blocks based on local characteristics such as intra prediction mode. This local adaptation improves compression ratio by matching the transform type to the local signal characteristics, while computational complexity is managed by applying transforms only where beneficial rather than uniformly across all blocks
Data Source
AI summary
Aspects of the disclosure provide methods, apparatuses, and non-transitory computer-readable storage mediums for video encoding/decoding. A non-transitory computer readable medium stores a video media bitstream encoded by an encoding method that includes selecting a secondary transform core for coding a current block. The secondary transform core has a size of M×N. The encoding method includes applying a forward primary transform to a transform unit of the current block to generate a primary transform coefficient block having a size of W×H. One of H or W is less than M and N. The secondary transform core is applied to the primary transform coefficient block by applying a sub-section of the secondary transform core to the primary transform coefficient block. A secondary transform coefficient block is generated. The encoding method includes encoding, in the video media bitstream, the current block based on an intra prediction mode and the secondary transform coefficient block.