Digital Video Bitstream Rewriting for Cross-Decoder Loss Recovery
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Solution Overview
Problem
Different video decoders implement varying loss recovery strategies, leading to issues such as blank or frozen screens when encoded data is lost due to network congestion, as they may not be compatible with the encoder's strategy, resulting in decoding failures.
Innovation Solution
A bitstream rewriter modifies the incoming bitstream to make it more resilient to loss of encoded data by changing syntax elements, ensuring compatibility with different decoder loss recovery strategies, while maintaining video quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different decoders use different loss recovery strategies, then each decoder can be optimized for its specific strategy, but inter-operability between decoders deteriorates, causing blank or frozen screens when encoded data is lost
Solution Approach 1:
The patent applies universality by making the bitstream structure itself adaptable to multiple decoder types. By modifying syntax elements to be compatible with both IDR-picture-based and LTR-picture-based decoders, the solution enables a single bitstream to serve multiple decoder implementations without requiring decoder-specific encoding variants.
Solution Approach 2:
The patent changes bitstream parameters (syntax elements) to resolve the contradiction. Specifically, it modifies reference picture marking syntax and picture type indicators to ensure that decoders using different loss recovery strategies can correctly interpret and process the bitstream, preventing decoding failures while maintaining optimized recovery behavior.
2Reliability
If the bitstream is modified to be more resilient to data loss, then decoder performance under lossy conditions improves, but the complexity of the bitstream processing increases
Solution Approach 1:
The patent applies preliminary action by pre-modifying the bitstream syntax elements before transmission to anticipate potential data loss. The bitstream rewriter proactively adjusts reference picture markings and picture type indicators in advance, so that when data loss occurs during transmission, the decoder can reliably recover without requiring complex real-time error correction mechanisms.
3Productivity
If loss recovery strategies are made decoder-specific, then recovery efficiency for each decoder type improves, but the time required for decoders to handle unexpected loss patterns increases
Solution Approach 1:
The patent applies feedback by enabling decoders to reliably detect picture types and reference picture markings even under lossy conditions. The modified syntax elements provide clear, unambiguous signals that allow decoders to quickly determine their recovery path without guessing or attempting multiple recovery strategies, thereby reducing recovery time while maintaining high recovery speed through appropriate strategy selection.
Data Source
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AI summary
Ways to mitigate loss in inter-operability scenarios for digital video are presented. For example, a bitstream modification tool (such as a bitstream rewriter running on a network node of a videoconferencing system) receives an incoming bitstream of encoded video (e.g., from an encoder that uses a first loss recovery strategy). The bitstream modification tool processes the incoming bitstream of encoded video to produce an outgoing bitstream of encoded video. In doing so, the bitstream modification tool changes at least one syntax element between the incoming bitstream and the outgoing bitstream so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions. The bitstream modification tool outputs the outgoing bitstream. In this way, the bitstream modification tool can help avoid blank screens, frozen screens, or other failures during decoding under lossy delivery conditions (e.g., with a decoder that uses a different loss recovery strategy).