Chroma Block Prediction Thresholds in Video Coding
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Solution Overview
Problem
High-Efficiency Video Coding (HEVC) and emerging Versatile Video Coding (VVC) face inefficiencies in processing throughput due to small block sizes, particularly in chroma blocks, leading to pipeline delays and inefficient memory access in hardware implementations.
Innovation Solution
The proposed method disables the additional hypothesis of prediction for chroma blocks when using multi-hypothesis prediction modes like Combined Inter/Intra Prediction (CIIP), Triangular Prediction (TPM), or Geometric Merge (GEO) modes, ensuring that only the existing hypothesis is used for chroma blocks if their width, height, or area is below a certain threshold, thereby simplifying the prediction process and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-hypothesis prediction modes (CIIP, TPM, GEO) are applied to small chroma blocks, then coding efficiency is improved, but processing throughput deteriorates due to pipeline delays and memory access inefficiencies
Solution Approach 1:
The patent applies different prediction strategies to different regions: luma blocks use multi-hypothesis prediction modes (CIIP, TPM, GEO) while chroma blocks use simplified prediction. This local differentiation allows high coding efficiency for luma while avoiding the throughput penalties of applying complex multi-hypothesis prediction to small chroma blocks.
Solution Approach 2:
The patent changes the prediction mode parameter for chroma blocks based on block size conditions. When chroma block dimensions fall below thresholds (e.g., width < 8 or height < 8), the multi-hypothesis prediction is disabled and standard prediction is used instead, thereby improving processing throughput for small blocks while maintaining coding efficiency for larger blocks.
2Measurement precision
If multi-hypothesis prediction modes are applied to small chroma blocks, then prediction accuracy is improved, but device complexity increases leading to inefficient memory access
Solution Approach 1:
The patent applies complex multi-hypothesis prediction only where needed (luma blocks) and uses simplified prediction for chroma blocks, particularly small ones. This reduces memory access complexity and device complexity for chroma processing while maintaining prediction accuracy where it matters most for visual quality.
Solution Approach 2:
For small chroma blocks, the patent uses simpler, less resource-intensive prediction methods that require fewer memory accesses and less complex processing. This trades off some prediction accuracy for significantly reduced device complexity and more efficient memory access patterns.
Data Source
AI summary
A method and apparatus for video coding are disclosed. According to this method, a current block is received at an encoder side or compressed data comprising the current block is received at a decoder side, wherein the current block comprises one luma block and one or more chroma blocks, the current block is generated by partitioning an image area using a single partition tree into one or more partitioned blocks comprising the current block. A target coding mode is determined for the current block. The current block is then encoded or decoded according to the target coding mode, wherein an additional hypothesis of prediction for said one or more chroma blocks is disabled if the target coding mode corresponds to the multi-hypothesis prediction mode and width, height or area of said one or more chroma blocks is smaller than a threshold.