Video Decoder Frame Buffer Management for Rewind Playback
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Solution Overview
Problem
Conventional video decoders face challenges during rewind and fast forward operations in MPEG streams, as they require decoding multiple pictures within a time limit, leading to reduced video quality due to repetitive decoding of prediction pictures.
Innovation Solution
The system improves video decoder performance by storing and directly displaying prediction pictures from a frame buffer, avoiding repetitive decoding by setting future prediction pictures as past or reference pictures during fast forward and rewind operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the decoder decodes multiple pictures in forward order to display a single picture during rewind operation, then the rewind function can be achieved, but the video quality suffers due to repetitive decoding
Solution Approach 1:
The patent applies preliminary action by pre-decoding and storing multiple pictures in frame buffers before the rewind operation is needed. When rewind is initiated, the decoder has already prepared the necessary prediction pictures in memory, eliminating the need for repetitive decoding during the actual rewind playback. This ensures both smooth rewind operation and maintains video quality by avoiding repeated decoding cycles.
2Productivity
If the decoder decodes multiple pictures within a time limit, then the trick play operation can be performed, but video quality deteriorates due to the time constraint
Solution Approach 1:
The system pre-decodes and stores multiple prediction pictures in frame buffers before trick play operations are required. This preliminary preparation allows the decoder to quickly retrieve and display pictures during fast forward or rewind without being constrained by decoding time limits, thereby maintaining video quality while enabling smooth trick play operations.
Solution Approach 2:
The patent implements beforehand cushioning by maintaining multiple frame buffers with pre-decoded pictures ready for rapid access. This buffer cushioning ensures that when trick play operations occur, the decoder can immediately retrieve pictures without time pressure, preventing quality deterioration while maintaining high operational speed.
3Productivity
If the decoder stores prediction pictures in frame buffer, then repetitive decoding is avoided, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing frame buffers that serve multiple functions: they store prediction pictures for both forward and backward playback operations, and can be reused across different trick play scenarios. This multi-functional approach avoids the need for separate storage structures for different operations, thereby reducing overall device complexity while maintaining high decoding efficiency.
Data Source
AI summary
Presented herein are systems, methods, and apparatus for improving performance of video decoders during rewind and fast forward operation. Video decoder performance is improved by avoiding repetitive decoding of prediction pictures. When a decoded prediction picture is stored in a frame buffer, techniques are presented for decoding multiple pictures in the rewind order which are dependent thereon, displaying the picture directly from the frame buffer, and setting one type of prediction picture as another type of prediction picture.