Reverse Video Playback Using Pre-Decode Buffering
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Solution Overview
Problem
Traditional methods for playing video streams backward are inefficient, requiring extensive decoding and caching, leading to high latency and increased time consumption, especially when dealing with large video streams.
Innovation Solution
A method for reverse video playback that decodes from the I-frame to the last frame, saves pre-decoded frames in a storage module, and pre-decodes frames as needed, reducing latency by utilizing a storage module to cache and output frames efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frames are decoded sequentially from I-frame to the required frame in traditional reverse playback, then decoding accuracy is maintained, but latency time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-decoding frames from the I-frame to the last frame in advance and storing them in a buffer before reverse playback is requested. When reverse playback is needed, the pre-decoded frames are already available in the buffer, eliminating the need to decode them in real-time and thus significantly reducing latency time while maintaining decoding accuracy.
2Productivity
If all decoded frames are saved to a cache block in advance, then playback speed improves, but cache block capacity requirements increase
Solution Approach 1:
The patent segments the video stream into groups of pictures (GOPs), where each GOP contains an I-frame and subsequent non-I-frames. Only the necessary frames within each GOP are pre-decoded and stored in the buffer, rather than caching the entire video stream. This segmentation approach improves playback speed while reducing the overall cache block capacity requirements.
Solution Approach 2:
The patent applies partial action by pre-decoding only the necessary portion of frames (from I-frame to last frame in each GOP) rather than the entire video stream. This partial pre-decoding provides sufficient frames for reverse playback without requiring excessive cache block capacity, thus improving playback speed while controlling memory usage.
3Loss of time
If frame caching is implemented for reverse playback, then decoding time is saved, but device complexity increases
Solution Approach 1:
The patent uses preliminary action to pre-decode and buffer frames before reverse playback is requested. This approach saves decoding time during actual playback while managing device complexity by implementing the buffering mechanism at the frame level with clear entry and exit conditions, avoiding overly complex system architecture.
Data Source
AI summary
A method for reverse video playback and a computer-readable medium are provided for playing a video stream backward. The video stream includes a plurality of groups of pictures which includes a plurality of frames. The frames include one I-frame and at least one frame which is a non-I-frame. The said method includes decoding from the I-frame to a last one frame in a group of pictures according to the time sequence, outputting the last one frame, saving at least one frame which is not outputted in the group of pictures to a storage module, pre-decoding the frames which is not outputted and saved in the group of picture, outputting the frame which is in the storage module.