Chroma Transform Unit Encoding and Decoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current video coding standards, such as H.264/MPEG-4 AVC, face challenges in efficiently encoding and decoding residual coefficients for transform units, particularly when scaling to high resolutions and frame rates, due to complexity and size issues related to supporting multiple transform sizes.
Innovation Solution
A method for decoding and encoding chroma residual coefficients involves determining the size of a transform unit based on its hierarchical level, identifying the maximum number of inverse or forward transforms, and applying selected transforms from a predetermined set to decode or encode chroma residual samples, optimizing the process for chroma formats like 4:2:2 and 4:4:4.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transform sizes are supported for transforming video data between frequency domain and spatial domain, then the adaptability of the video coding standard is improved, but the device complexity increases
Solution Approach 1:
The transform unit is divided into multiple sub-transform units, each handling a specific transform size. The logic is segmented into separate processing paths for different transform sizes (e.g., 4x4, 8x8, 16x16, 32x32), allowing independent optimization of each segment rather than requiring a single complex logic structure to handle all sizes.
Solution Approach 2:
The transform processing logic is made dynamic by using switchable processing paths that are selected based on the transform size indication in the bitstream. The system can adaptively activate or deactivate specific transform processing modules depending on the required transform size, enabling flexible support for multiple sizes without permanently instantiating all possible transform logics.
2Adaptability or versatility
If multiple transform sizes are supported, then the versatility of video coding is improved, but the productivity decreases due to increased processing overhead
Solution Approach 1:
The system performs preliminary setup by pre-configuring multiple transform processing modules for different transform sizes before actual video processing begins. Each module is pre-optimized for its specific transform size, allowing rapid switching between sizes during processing without requiring complex runtime calculations or dynamic reconfiguration.
Solution Approach 2:
The processing system dynamically selects and activates only the transform processing module corresponding to the current transform size required by the bitstream. This dynamic activation reduces processing overhead by avoiding unnecessary computations in modules for transform sizes that are not currently needed, thereby maintaining real-time processing capability.
3Measurement precision
If chroma residual coefficients are decoded using maximum number of transforms, then the measurement precision of chroma channel is improved, but the device complexity increases
Solution Approach 1:
Different transform processing precision is applied locally to different chroma regions based on their specific requirements. The system determines the appropriate number of transforms needed for each chroma residual coefficient array based on local characteristics such as region size and content complexity, rather than uniformly applying maximum transforms to all regions.
Solution Approach 2:
The number of transforms applied to chroma residual coefficients is dynamically determined based on the specific requirements of each transform unit. The system adaptively selects the maximum number of transforms needed for each chroma channel based on factors such as the transform unit size, chroma format, and residual coefficient distribution, optimizing precision while avoiding unnecessary processing complexity.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Disclosed is method (1100) of decoding, from a video bitstream, a transform unit containing at least one chroma residual coefficient array associated with a single chroma channel. The method determines (1102) a size of the transform unit related to a hierarchical level of the transform unit in a corresponding coding unit, and identifies (1104) a maximum number of inverse transforms according to the determined size. The method decodes (1106) from the video bitstream the at least one chroma residual coefficient array using the identified maximum number of transforms, selects (1108) an inverse transform for the decoded chroma residual coefficient arrays, the inverse transform being selected from a predetermined set of inverse transforms, and applies (1110) the selected inverse transform to each of the chroma residual coefficient arrays to decode chroma residual samples for the chroma channel of the transform unit. A similar encoding method is also disclosed.