Video Decoder Transform Unit Size Adaptation
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Solution Overview
Problem
The HEVC standard's constant transformation method, regardless of transform unit sizes, deteriorates the compression rate of videos, as it fails to optimize transform methods based on varying sizes of transformation units.
Innovation Solution
The proposed solution involves using different transform methods, such as Discrete Cosine Transform (DCT) and Discrete Sine Transform (DST), based on the size of transform units, where DST is applied for minimum size units like 4×4 and DCT for larger units, to improve compression efficiency during both encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant transformation method is used regardless of transform unit sizes, then the device complexity is reduced, but the compression rate deteriorates
Solution Approach 1:
The patent applies different transform methods (DST, DCT, DST-II, DCT-II) to different transform unit sizes (4×4, 8×8, 16×16, 32×32) based on local characteristics. Specifically, DST is applied to 4×4 units, DST-II to 8×8 units, DCT-II to 16×16 units, and DCT to 32×32 units, optimizing compression for each local size category rather than using a single global transform method
Solution Approach 2:
The patent changes the transform method parameter based on the transform unit size parameter. By dynamically selecting among four different transform methods according to the specific size of each transform unit, the system adapts the transformation parameters to local requirements, improving compression efficiency without significantly increasing complexity
2Productivity
If different transform methods are applied based on transform unit sizes, then the compression rate is improved, but the device complexity increases
Solution Approach 1:
The patent divides the video data into different transform unit size categories (4×4, 8×8, 16×16, 32×32) and applies locally optimized transform methods to each category. This localized approach improves compression for each specific size while keeping the overall system manageable through systematic categorization
Solution Approach 2:
The patent systematically varies the transform method parameter according to transform unit size, creating a scalable framework where the complexity increases gradually and predictably with unit size rather than requiring complex decision logic for each individual block
Data Source
AI summary
The present disclosure provides an apparatus for decoding a video, the apparatus including at least: a bitstream decoder configured to extract information on a size of a transform unit and generate a quantized frequency transform block from a bitstream; an inverse quantization unit configured to reconstruct a frequency transform block by inversely quantizing the quantized frequency transform block; an inverse transformer configured to reconstruct a residual block by inversely transforming the frequency transform block, the inverse transformer selecting an inverse transform scheme among a plurality of inverse transform schemes in consideration of the size of the transform unit; a predictor configured to generate a predicted block in a prediction mode selected among an intra prediction mode and an inter prediction mode; and an adder configured to reconstruct a current block by adding a first pixel corresponding to the residual block and a second pixel corresponding to the predicted block.