Remultiplexing Video Bitstreams for Seek Performance
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Solution Overview
Problem
Video files encoded without indexing information add complexity to playback and editing systems, particularly during seek or scrubbing operations, due to the multiplexing of compressed video data with other data in packetized formats like M2TS.
Innovation Solution
Processing the encoded bitstream to recombine multiple packets into contiguous data for each image with associated presentation timestamps, and marking intraframe compressed images as recovery points to empty decompression buffers, facilitating efficient seek and scrubbing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If video data is encoded using multiplexed packetized formats (M2TS) with multiple packets per image, then streaming playback performance is optimized, but playback and editing system complexity increases due to lack of indexing information
Solution Approach 1:
The patent segments the bitstream processing into distinct phases: original bitstream processing for streaming, converted bitstream processing for editing/scrubbing, and recovery point marking for buffer management. This segmentation allows each format to be optimized for its specific purpose without increasing overall system complexity.
Solution Approach 2:
The patent introduces a converted bitstream as an intermediary format between the original M2TS bitstream and the playback/editing system. This intermediary contains reorganized packets with indexing information and recovery point markers, simplifying the playback system without sacrificing streaming performance.
2Loss of energy
If multiple packets are used for each image in the bitstream, then data compression efficiency is improved, but seek and scrubbing operations become more complex without indexing information
Solution Approach 1:
The patent performs preliminary reorganization of packets into a converted bitstream with indexing information before seek/scrubbing operations are needed. Recovery points are pre-marked at intraframe compressed images, enabling fast forward seeking without complex buffer management during the actual seek operation.
Solution Approach 2:
The patent creates a converted bitstream that is a reorganized copy of the original bitstream. This copy maintains the same compression efficiency but adds indexing information and recovery point markers, making seek and scrubbing operations simpler without affecting the original streaming performance.
3Device complexity
If recovery points are marked at intraframe compressed images, then buffer management during seek operations is simplified, but processing time for bitstream conversion increases
Solution Approach 1:
The patent applies recovery point marking selectively only at intraframe compressed images rather than uniformly across all frames. This localized approach simplifies buffer management at critical points (I-frames) where buffer clearing is most important, while avoiding the processing overhead of marking every frame.
Data Source
AI summary
An encoded bitstream is processed without re-encoding so as to recombine multiple packets of each image into contiguous data of one packet for the image. Each packet is assigned a presentation time stamp, corresponding to the display order of its image in the sequence of images. In one embodiment, each intra-frame compressed image also is marked as a recovery point indicating that a decompression processor empties its buffers of data for prior groups of pictures before processing the image. A video editing or other playback application uses the converted bitstream for scrubbing and similar playback operations.