B Picture Decoding with Missing Forward References
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Solution Overview
Problem
Video compression standards like AVS1-P2 face challenges in decoding B pictures when their forward reference pictures are missing or invalid, leading to incomplete video decoding and potential artifacts during playback.
Innovation Solution
A method and system for processing B pictures that involve decoding a contiguous sequence of B pictures following a sequence header, where missing or invalid forward reference pictures are handled by discarding them or interpolating new pictures using the available forward and backward reference pictures, ensuring seamless video playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If B pictures use forward reference pictures for decoding, then decoding efficiency is improved, but decoding fails when forward reference pictures are missing or invalid
Solution Approach 1:
The patent applies preliminary action by checking the validity of forward reference pictures before attempting to decode B pictures. The system performs advance validation to determine if forward reference pictures are missing or invalid, and prepares alternative decoding paths (using only backward reference pictures) before the actual decoding process occurs, preventing decoding failures.
Solution Approach 2:
The patent changes the decoding parameters dynamically based on the validity of forward reference pictures. When forward reference pictures are valid, the system uses bi-directional prediction with both forward and backward references. When they are missing or invalid, the system switches to using only backward reference pictures, effectively changing the decoding parameters to maintain reliability.
2Reliability
If B pictures are discarded when forward reference is invalid, then decoding reliability is improved, but video continuity is lost
Solution Approach 1:
The patent extracts only the necessary reference picture information for decoding. When forward reference pictures are invalid, the system extracts and uses only the backward reference picture information, discarding the problematic forward reference data. This selective extraction maintains decoding reliability while preserving video continuity through the available reference pictures.
3Duration of action of stationary object
If interpolation is used to generate missing forward reference pictures, then video continuity is maintained, but computational complexity increases
Solution Approach 1:
The patent uses backward reference pictures as an intermediary to compensate for missing or invalid forward reference pictures. Instead of complex interpolation algorithms, the system leverages the available backward reference pictures to maintain decoding continuity, reducing computational complexity while preserving video playback.
Data Source
AI summary
Methods and systems for processing B pictures with missing or invalid forward reference pictures are disclosed. Aspects of one method may include decoding of a contiguous sequence of B pictures that immediately follow a first I picture after a sequence header. The decoding of the B pictures may handle video edit codes in the AVS1-P2 format and/or random access points. Some embodiments of the invention may discard B pictures that refer to invalid or missing forward reference pictures, while other embodiments of the invention may interpolate B pictures. For an invalid forward reference picture, the interpolation algorithm for generating pictures may use the invalid forward reference picture and the backward reference picture. For a missing decoded forward reference picture, as in a random access, the interpolation algorithm for generating pictures may use the backward reference picture.