Conditional Signaling for Video Coding Merge Lists
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving improved compression ratios with minimal sacrifice in picture quality, particularly in the harmonization of multi-hypothesis prediction for intra and inter mode techniques and separate merge lists for subblock merge candidates.
Innovation Solution
The proposed method involves using a first technique for separate merge lists for subblock merge candidates and a second technique for multi-hypothesis prediction for intra and inter mode, with conditional signaling of control flags to determine their usage, allowing independent control of these techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-hypothesis prediction for intra and inter mode is used, then coding efficiency is improved, but signaling overhead increases
Solution Approach 1:
The patent applies dynamics by making the signaling of multi-hypothesis prediction flags conditional rather than static. The second flag (mh_intra_flag) is only signaled when the first flag (merge_subblock_flag) indicates that separate merge lists are not used. This dynamic signaling approach adapts the information transmitted based on the coding mode, improving coding efficiency by avoiding redundant signaling while maintaining the ability to use multi-hypothesis prediction when beneficial.
Solution Approach 2:
The patent changes the parameter of flag signaling from a fixed approach to a conditional approach. By modifying the signaling behavior based on the value of merge_subblock_flag, the system optimizes the balance between coding efficiency and signaling overhead. This parameter change allows the encoder to adaptively control which prediction techniques are signaled and used, resolving the contradiction between improved compression and reduced signaling.
2Measurement precision
If separate merge lists for subblock merge candidates are used, then prediction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the merge candidate list into separate subblock-specific lists. Instead of using a single unified merge list for the entire block, the system creates separate merge lists for different subblocks, allowing each subblock to have more accurate and relevant prediction candidates. This segmentation improves prediction accuracy by providing subblock-level optimization while the conditional flag mechanism helps manage the associated complexity.
3Productivity
If both multi-hypothesis prediction and separate merge lists are used together, then coding gains are maximized, but signaling overhead and complexity increase significantly
Solution Approach 1:
The patent uses dynamics to enable flexible and adaptive usage of both multi-hypothesis prediction and separate merge lists. Through the conditional flag mechanism, the system can dynamically select and combine different prediction techniques based on the specific coding context. This allows the encoder to maximize coding gains by using both techniques together when beneficial, while avoiding the signaling overhead of always transmitting both flags, thus resolving the contradiction between maximizing coding gains and minimizing signaling overhead.
Data Source
AI summary
The present disclosure relates to methods and apparatuses for encoding video data into a bitstream and for decoding video data received in a bitstream. A second control flag indicating whether or not to use multi-hypothesis prediction for intra and inter mode is generated and transmitted only conditionally, upon a determination whether or not separate merge list technique for subblock merge candidates is used. On the other hand, a decoder is capable of deciding usage of multi-hypothesis prediction for intra and inter mode and separate merge list technique for subblock merge candidates even though the second control flag is transmitted only conditionally.