Adaptive Multiple Transform Coding for Video Blocks
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Solution Overview
Problem
Current video coding technologies face challenges in efficiently compressing video data due to high redundancy, leading to increased memory and computational complexity, particularly with adaptive multiple transform (AMT) designs that are restricted to blocks with widths and heights less than or equal to 32, limiting coding gains and increasing complexity.
Innovation Solution
The proposed techniques improve AMT performance by relaxing restrictions on block sizes for AMT usage and introducing implicit or explicit signaling based on block dimensions, allowing AMT transforms in larger blocks and reducing signaling overhead by fixing transforms based on width and height thresholds, thereby optimizing transform selection without explicit signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If adaptive multiple transform (AMT) is restricted to blocks with width and height less than or equal to 32, then device complexity is reduced, but coding efficiency is improved
Solution Approach 1:
The patent changes the block size parameter threshold from 32 to 64, allowing AMT to be applied to larger blocks. This parameter change enables better coding efficiency for larger blocks while maintaining manageable device complexity through the established threshold-based approach.
Solution Approach 2:
The patent introduces dynamic transform selection based on block size, where the transform type is adaptively chosen according to the actual block dimensions. This dynamic approach allows the system to optimize coding efficiency for each block while managing complexity through conditional logic rather than universal complexity.
2Measurement precision
If explicit signaling is used for transform selection, then transform accuracy is improved, but signaling overhead is increased
Solution Approach 1:
The patent applies partial signaling by using explicit transform indexing only when block sizes exceed the threshold (greater than 64). For smaller blocks, the default transform is used without explicit signaling. This partial action approach reduces overall signaling overhead while maintaining transform accuracy where it provides the most benefit.
Solution Approach 2:
The patent applies different signaling strategies to different block size regions: explicit signaling for large blocks (greater than 64) and default transforms for smaller blocks. This local differentiation optimizes the balance between transform accuracy and signaling overhead based on the specific characteristics of each block size category.
3Productivity
If AMT is applied to larger blocks, then coding gains are improved, but computational complexity is increased
Solution Approach 1:
The patent changes the applicable block size parameter from maximum 32 to maximum 64, enabling AMT to process larger blocks. This parameter change improves coding gains for larger blocks while the computational complexity is managed through the threshold-based selective application rather than universal application to all blocks.
Solution Approach 2:
The patent segments the block processing into two categories: blocks with size greater than 64 that receive explicit transform indexing, and smaller blocks that use default transforms. This segmentation allows computational resources to be focused on larger blocks where AMT provides the most coding gain, while reducing overall computational complexity through the segmented approach.
Data Source
AI summary
Techniques are described for improving transform coding. For example, an encoded block of video data can be obtained, and a width and/or a height of the block can be determined. The width can be compared to a first threshold and/or the height can be compared to a second threshold. A horizontal transform and a vertical transform can be determined for the block based on comparing the width of the block to the first threshold and/or the height of the block to the second threshold. The horizontal transform and the vertical transform are determined without decoding a syntax element that indicates the horizontal transform and the vertical transform (e.g., the syntax element is not in an encoded video bitstream processed by a decoding device). In some cases, residual data is determined using the horizontal and vertical transforms, and a video block is determined using the residual data and a predictive block.