Decoder Derived Cross Component Prediction Video Coding
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Solution Overview
Problem
Existing video encoding and decoding techniques face significant signaling overhead when determining the specific cross-component prediction (CCP) mode for blocks of video data, which can increase distortion due to lossy encoding.
Innovation Solution
A method where a video decoder derives the CCP mode without explicit signaling by comparing prediction values from different CCP modes to actual values, selecting the mode with the lowest difference, and using a flag to indicate whether the CCP mode is derived or signaled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If explicit signaling is used to indicate CCP mode for each block, then the decoder can accurately determine the prediction mode, but the signaling overhead increases significantly
Solution Approach 1:
The decoder autonomously determines the CCP mode by evaluating multiple candidate modes and selecting the one with the lowest rate-distortion cost, without requiring explicit signaling from the encoder. This self-service mechanism eliminates the need for additional signaling bits while maintaining accurate mode selection through local optimization.
Solution Approach 2:
The system changes the parameter being signaled from a direct CCP mode indicator to a derivation flag. By signaling only whether to derive the mode rather than the mode itself, the patent reduces the number of bits required while enabling the decoder to reconstruct the appropriate mode through evaluation of candidate modes based on rate-distortion metrics.
2Manufacturing precision
If multiple CCP modes are evaluated to reduce distortion, then the prediction accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent transforms the complexity from mode selection logic to rate-distortion evaluation of a fixed set of candidate modes. By changing the approach from searching for the optimal mode to evaluating predefined candidates with mathematical formulas, the system achieves high prediction accuracy through systematic parameter optimization rather than complex decision logic.
Solution Approach 2:
The patent pre-defines a set of candidate CCP modes that are likely to be optimal for different block types. By preparing these candidates in advance and evaluating them systematically using rate-distortion metrics, the decoder avoids the need for complex real-time mode search algorithms while maintaining high prediction accuracy.
3Adaptability or versatility
If a flag is used to indicate whether CCP mode is derived or signaled, then the system maintains flexibility, but additional signaling bits are required
Solution Approach 1:
Instead of signaling the complete CCP mode information, the patent uses a partial signal (a single derivation flag) that enables the decoder to reconstruct the necessary information locally. This partial signaling approach provides sufficient flexibility for different block types while minimizing the number of bits required compared to full mode signaling.
Data Source
AI summary
A video decoder may be configured to receive a first instance of a flag for a first block, with a first value for the flag indicating that a cross-component prediction (CCP) mode is derived without signaling and a second value for the flag indicating that the CCP mode is signaled; in response to determining that the first instance of the flag is set to the first value, derive a first CCP mode for the first block; determine a first predicted chroma block for the first block using the first CCP mode; determine a decoded version of the first block based on the first predicted chroma block; and output a picture of decoded video data that includes the decoded version of the first block.