Video Signal Decoding with Adaptive Transform Kernel Selection
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Solution Overview
Problem
Current video signal processing methods face inefficiencies in transforming high spatial resolution, high frame rate, and high-dimensional video content, particularly in applying transforms that are not optimized for specific blocks, leading to increased memory storage and processing demands.
Innovation Solution
A method and device for decoding video signals that parse syntax elements to determine the applicability of primary and secondary transforms, using predefined kernels like DCT2, and selecting appropriate transform kernels based on intra prediction modes to efficiently process blocks, thereby optimizing transform efficiency and compression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transform kernel is applied to all blocks, then device complexity is reduced, but transform efficiency deteriorates
Solution Approach 1:
The patent implements dynamic transform kernel selection where the transform kernel is adaptively chosen based on block characteristics such as prediction mode and block size. The decoder determines whether to apply a secondary transform kernel based on syntax elements in the bitstream, allowing the transform processing to dynamically adapt to different block types rather than using a fixed kernel for all blocks.
Solution Approach 2:
The patent applies different transform kernels to different regions (blocks) of the video signal based on local characteristics. Specifically, a secondary transform kernel is applied only to certain blocks where it provides benefit, while other blocks use the primary transform kernel only. This localized application optimizes transform efficiency for each block's specific characteristics.
2Productivity
If transform kernels are optimized for specific blocks, then transform efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies the secondary transform kernel only partially - specifically to blocks where the prediction mode indicates it would be beneficial (e.g., certain intra prediction modes). The decoder checks syntax elements to determine whether to apply the secondary transform, avoiding its application to all blocks. This partial application provides the efficiency benefits where needed while limiting the complexity increase.
3Loss of information
If multiple transform kernels are used, then compression performance is improved, but memory storage requirements increase
Solution Approach 1:
The patent designs the transform kernel system to be universal across different block types. A set of predefined secondary transform kernels is established that can be applied to various block types depending on the prediction mode. The same kernel set serves multiple functions across different intra prediction modes, reducing the need for separate kernels for each mode and thereby limiting memory storage requirements.
Data Source
AI summary
A method and a device for processing a video signal are disclosed. In particular, a method for decoding a video signal includes parsing a first syntax element indicating a primary transform kernel applied to a primary transform of a current block; determining whether a secondary transform is applicable to the current block based on the first syntax element; if the secondary transform is applicable to the current block, parsing a second syntax element indicating a secondary transform kernel applied to a secondary transform of the current block; deriving a secondary inverse-transformed block, by performing a secondary inverse-transform for a top-left specific region of the current block using a secondary transform kernel indicated by the second syntax element; and deriving a residual block of the current block, by performing a primary inverse-transform for the secondary inverse-transformed block using a primary transform kernel indicated by the first syntax element.