Video Transform Core Selection for Intra Block Compression
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving efficient compression ratios with minimal quality loss, particularly in handling transform blocks of varying sizes and shapes, which affects the overall efficiency and quality of video encoding and decoding processes.
Innovation Solution
The implementation of a method that determines the appropriate transform core (DST-7 or DCT-2) based on specific threshold conditions for the width and height of transform blocks, optimizing the transform process for intra prediction in video coding, and employing a Multiple Transform Selection scheme to select the most suitable transform for each block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transform core (DCT-2) is used for all transform blocks, then the device complexity is reduced, but the compression efficiency and picture quality deteriorate for certain block sizes
Solution Approach 1:
The patent applies parameter changes by selecting different transform cores (DCT-2 or DST-7) based on the transform block width parameter. When the width falls within a specific range (4 to 16 inclusive), DST-7 is selected instead of the default DCT-2, optimizing compression efficiency for blocks with aspect ratios between 0.25 and 4.0 without significantly increasing device complexity.
2Productivity
If different transform cores are selected for different block sizes, then the compression efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent implements parameter-based transform selection where the transform core is determined by evaluating the transform block width against predefined thresholds. This approach balances compression efficiency improvement with controlled device complexity by using simple comparison logic rather than complex adaptive algorithms.
Solution Approach 2:
The patent applies local quality by using DST-7 transform specifically for transform blocks with widths between 4 and 16 pixels, which typically correspond to blocks with aspect ratios between 0.25 and 4.0. This targeted application optimizes compression for specific local block characteristics while using standard DCT-2 for other blocks, avoiding unnecessary complexity for all block types.
3Productivity
If transform block width is within specific range, then compression efficiency is improved by using DST-7, but additional processing logic is required
Solution Approach 1:
The patent uses parameter changes by establishing a width threshold range (4 to 16 pixels) that triggers DST-7 transform selection. This simple parameter-based decision rule improves compression ratio for applicable blocks while adding minimal processing logic compared to always using a single transform type.
Data Source
AI summary
The present disclosure provides methods and devices. A video method of coding implemented by a decoding device, comprising: when a prediction mode of a current coding block is intra prediction, and the current coding block is processed by using Intra sub-partition coding mode, determining whether a height of a current transform block is larger than or equal to a first threshold or not, and whether the height of the current transform block is smaller than or equal to a second threshold or not, the current transform block corresponding to the current coding block; when the height of the current transform block is larger than or equal to the first threshold and the height of the current transform block is smaller than or equal to the second threshold, performing transform process on the current transform block, wherein a transform core based on DST 7 is used on vertical direction transform.