Merge Flag Coding with Zero-Motion Candidates for Robust Parsing
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Solution Overview
Problem
Current merge mode in video coding standards like HEVC introduces overhead and error sensitivity due to conditional encoding of the merge flag, which depends on the size of the merging candidate list, making bit stream parsing less efficient and error resilient.
Innovation Solution
Decoupling the encoding of the merge flag from the merging candidate list size ensures that a merge flag is always encoded for each inter-predicted PU not using skip mode, allowing independent parsing and adding a zero motion vector candidate to guarantee a non-empty list, thus reducing overhead and enhancing error resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the merge flag encoding is conditional on the merging candidate list size, then the coding overhead is reduced when the list is empty, but the bit stream parsing becomes error-sensitive and less efficient
Solution Approach 1:
The patent adds a zero motion vector candidate to the merging candidate list in advance, before the merge flag encoding decision is made. This preliminary action ensures that the list is never empty, allowing the merge flag to be unconditionally encoded for all inter-predicted PUs, thereby eliminating error sensitivity while maintaining efficient coding overhead
Solution Approach 2:
The patent separates the merge flag encoding from the merging candidate list construction by ensuring the list always contains at least one candidate (the zero motion vector candidate). This segmentation allows the merge flag to be independently encoded without dependency on the dynamic state of the candidate list, improving both parsing efficiency and error resilience
2Adaptability or versatility
If the merge flag encoding depends on the merging candidate list construction, then the encoding process is adaptive to content, but the parsing overhead increases and error propagation risk increases
Solution Approach 1:
By pre-adding the zero motion vector candidate to the merging candidate list, the patent creates a consistent baseline structure that simplifies parsing. The decoder no longer needs to conditionally evaluate list emptiness, reducing parsing complexity while preserving coding adaptability through the merge flag
Solution Approach 2:
The patent extracts the zero motion vector candidate as a guaranteed element from the merging candidate list construction process. This extracted element serves as a fallback option that decouples the merge flag encoding decision from the dynamic list construction, reducing parsing complexity while maintaining adaptability
Data Source
AI summary
Methods and apparatus for parsing friendly and error resilient merge flag coding in video coding are provided. In some methods, in contrast to merging candidate list size dependent coding of the merge flag in the prior art, a merge flag is always encoded in the encoded bit stream for each inter-predicted prediction unit (PU) that is not encoded using skip mode. In some methods, in contrast to the prior art that allowed the merging candidate list to be empty, one or more zero motion vector merging candidates formatted according to the prediction type of the slice containing a PU are added to the merging candidate list if needed to ensure that the list is not empty and/or to ensure that the list contains a maximum number of merging candidates.