Hybrid SDST and DCT Transform Scheme for Video Coding
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Solution Overview
Problem
Existing video compression techniques, such as discrete cosine transforms, are inefficient in capturing the statistical properties of certain residual pixels, leading to suboptimal compression performance and increased bitstream size.
Innovation Solution
A hybrid transform scheme that combines symmetrical discrete sine transforms (SDST) and two-dimensional discrete cosine transforms (2D DCT) for inter-predicted blocks, allowing for more compact representation of residual signals while maintaining minimal overhead and encoding complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If discrete cosine transform (DCT) is used for video compression, then encoding complexity is kept low, but compression performance is suboptimal due to inability to capture statistical properties of certain residual pixels
Solution Approach 1:
The patent implements dynamic transform selection where the transform type (DST or DCT) is chosen adaptively based on the prediction mode and residual characteristics. The decoder determines the transform type from the bitstream and applies the appropriate transform, enabling the system to optimize compression performance for different residual patterns while maintaining manageable complexity through conditional logic rather than exhaustive processing
Solution Approach 2:
The patent changes the transform parameter (selecting between DST and DCT) based on the prediction mode and residual signal characteristics. By switching between different transform types according to the specific block properties, the system adapts to capture statistical properties of residual pixels more effectively, improving compression performance without requiring a completely complex new transform design
2Productivity
If a single transform type is used for all blocks, then encoding complexity is minimized, but compression performance deteriorates due to lack of adaptability to different residual signal characteristics
Solution Approach 1:
The system dynamically selects between DST and DCT transforms based on the prediction mode and residual characteristics of each block. The decoder receives transform type information in the bitstream and applies the appropriate transform, enabling adaptive optimization of compression performance for different residual patterns while managing complexity through conditional selection rather than processing all blocks with all transform types
Solution Approach 2:
Different transform types are applied to different blocks based on their specific characteristics. Inter-predicted blocks use DST while intra-predicted blocks use DCT, allowing each block to be processed with the transform best suited to its local properties, thereby improving overall compression performance without uniformly increasing complexity across all blocks
3Manufacturing precision
If symmetrical discrete sine transform (SDST) is used for inter-predicted blocks, then energy compaction and signal decorrelation improve, but transform selection and decoding complexity increase
Solution Approach 1:
The system dynamically selects DST for inter-predicted blocks to achieve better energy compaction and signal decorrelation. The transform type is determined based on the prediction mode, and the decoder applies the appropriate transform without requiring complex analysis, as the selection rule is predetermined by the block type
Solution Approach 2:
DST is specifically applied to inter-predicted blocks where it provides superior energy compaction and decorrelation properties, while DCT is used for intra-predicted blocks. This localized application of the most suitable transform to each block type achieves high signal decorrelation without requiring complex transform selection logic across all blocks
Data Source
AI summary
An apparatus for decoding a current block from an encoded bitstream includes a memory and a processor. The processor is configured to execute instructions stored in the memory to decode, from the encoded bitstream, a prediction mode of the current block and decode the current block using a transform type selected from a set that includes only a symmetrical discrete sine transform (SDST) and a two-dimensional discrete cosine transform (2D DCT). If the prediction mode is an inter prediction mode, the transform type used is the SDST. If the prediction mode is an intra prediction mode, the transform type used is the 2D DCT.