Video Transform Size Selection via Prohibited Lists
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Solution Overview
Problem
In video encoding systems, the increased number of available partition sizes and transform sizes for high-definition videos leads to a higher amount of additional information required for selecting the optimal sizes during decoding, making it difficult to concentrate energy on fewer transform coefficients, especially when large and small transform sizes have significant size differences.
Innovation Solution
The video encoding apparatus limits the transform sizes that can be selected by deriving a prohibited transform list based on partition shape information, reducing the amount of additional information needed and maintaining adaptability to local video properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transform sizes are available for high-definition videos, then adaptability to local video properties is improved, but the amount of additional information required for selecting transform sizes increases
Solution Approach 1:
The patent applies local quality by deriving a prohibited transform list specific to each partition based on its shape information. This allows the transform selection to be adapted locally to each partition's characteristics without requiring global configuration of all possible transform sizes, thus maintaining adaptability while reducing the overall amount of additional information needed.
Solution Approach 2:
The patent changes the parameter representation from a positive list of allowed transform sizes to a negative list of prohibited transform sizes. This parameter inversion reduces the amount of additional information required, as the prohibited list is typically shorter than the full set of possible transforms, while still maintaining the ability to select appropriate transform sizes for local video properties.
2Loss of energy
If large and small transform sizes are used with significant size differences, then energy concentration on low frequency components is improved, but the amount of codes for additional information increases
Solution Approach 1:
The patent derives the prohibited transform list based on partition shape information, allowing different transform size selections for different partition types. This local adaptation enables energy concentration to be optimized for each partition's characteristics without requiring extensive additional information to describe the transform selection strategy globally.
Solution Approach 2:
Instead of providing information about all possible transform sizes and their selection criteria, the patent uses a partial approach by only specifying the prohibited transforms. This reduces the amount of additional information while still enabling the decoder to select appropriate transform sizes for energy concentration based on the prohibited list and partition shape.
3Adaptability or versatility
If the number of available partition sizes and transform sizes is increased, then adaptability to high-definition videos is improved, but the encoding processing amount increases
Solution Approach 1:
The patent applies local quality by creating partition-specific prohibited transform lists based on shape information. This approach maintains adaptability to high-definition videos with various partition sizes while reducing encoding processing, as the decoder can determine allowed transforms locally without extensive global processing or configuration.
Solution Approach 2:
The patent extracts only the necessary constraint information (prohibited transforms) from the full set of possible transforms. This extraction approach maintains adaptability to high-definition videos by allowing flexible transform selection while reducing encoding processing by only transmitting the essential prohibition information rather than complete transform selection data.
Data Source
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AI summary
While maintaining a high degree of freedom in choosing partition sizes and transformation sizes adapted for local characteristics of videos, the amount of metadata is decreased. A video encoding apparatus (10) divides an input video into blocks of a prescribed size and encodes the video block by block. The video encoding apparatus is provided with: a prediction parameter determining portion (102) that decides the block partition structure; a predictive image producing portion (103) that generates predictive images, partition by partition, as prescribed by the partition structure; a transform coefficient producing portion (107) which applies one of the frequency transformations included in a prescribed transformation preset to prediction residuals, i.e. the differences between predictive images and the input video; a transform restriction deriving portion (104) which generates the list of transform candidate, i.e. lists of frequency transformations that can be applied to each partition, on the basis of partition format information; and a variable-length-encoding portion (108) which, on the basis of the list of transform candidate and the transformation preset, performs variable-length encoding on transformation selection flags.