Chroma Intra Prediction Mode Derivation for Video Coding
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Solution Overview
Problem
Conventional video coding techniques face limitations in improving coding efficiency and maintaining quality, particularly in the derivation of intra prediction modes for chroma components, which can lead to increased coding bits and reduced compression efficiency.
Innovation Solution
The proposed method involves determining a set of candidate intra prediction modes for chroma blocks based on decoder-side derivation and constructing an intra prediction mode candidate list, which improves coding efficiency and reduces coding bits while maintaining quality by utilizing previously decoded blocks or samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional intra prediction mode derivation is used for chroma blocks, then the coding process is simple, but coding efficiency is limited and coding bits increase
Solution Approach 1:
The patent applies preliminary action by deriving the intra prediction mode at the decoder side before actual decoding, using previously decoded blocks to determine the mode. This allows the encoder to skip transmitting mode information, reducing coding bits while maintaining efficiency. The decoder proactively determines modes using available reference blocks, eliminating the need for exhaustive mode searches.
Solution Approach 2:
The patent uses copying by reusing intra prediction modes from previously decoded chroma blocks or collocated luma blocks. Instead of calculating new modes, the system copies mode information from reference blocks, significantly reducing computational complexity and coding bit requirements while maintaining prediction accuracy.
2Manufacturing precision
If more candidate intra prediction modes are considered, then coding quality improves, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies local quality by constructing different candidate mode lists for different chroma blocks based on their specific characteristics and available reference blocks. Each block receives a customized set of candidate modes tailored to its local context, improving prediction quality without requiring exhaustive mode searches for all blocks, thus balancing quality and complexity.
Solution Approach 2:
The system performs preliminary filtering of candidate intra prediction modes using decoder-side derivation results before final mode selection. By pre-determining likely modes from previously decoded blocks, the system reduces the candidate set size, lowering processing complexity while maintaining quality through intelligent candidate selection.
3Loss of information
If intra prediction modes are derived using previously decoded blocks, then coding bits are reduced, but measurement precision of mode selection may be affected
Solution Approach 1:
The patent implements feedback by using previously decoded blocks as reference information for deriving intra prediction modes of current blocks. The decoded blocks provide feedback about the actual content and structure, allowing the system to make accurate mode selections based on real decoded data rather than theoretical models, maintaining precision while reducing bits.
Solution Approach 2:
The system performs preliminary analysis of previously decoded blocks to identify patterns and characteristics that inform mode selection for current blocks. By examining decoded reference blocks in advance, the system can accurately predict suitable modes without exhaustive searching, maintaining selection accuracy while reducing coding overhead.
Data Source
AI summary
Embodiments of the present disclosure provide a method for video processing. The method comprises: determining, during a conversion between a current chroma block of a video and a bitstream of the video, a set of candidate intra prediction modes (IPMs) for the current chroma block based on a decoder-side derivation of intra prediction mode (DDIPM); constructing an IPM candidate list for the current chroma block based on the set of candidate IPMs; and performing the conversion based on the IPM candidate list. Thereby, the proposed method can advantageously improve coding efficiency and reduce the coding bits while maintaining the coding quality.