Media Player Segment Caching for Real-Time Rewind Playback
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Solution Overview
Problem
Conventional rewind playback of media files is time-consuming and memory-intensive, especially on mid-to-low-end devices, due to the need to cache the entire media file and decode frames in reverse order, which leads to Out Of Memory issues.
Innovation Solution
A media player with a cache mechanism that caches segments of the media file, such as GOPs, allowing real-time rewind playback by fetching and decoding frames on-the-fly, reducing memory usage and load times through selective caching and frame resolution downscaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the entire media file is cached for rewind playback, then playback continuity is improved, but memory consumption increases causing Out Of Memory issues
Solution Approach 1:
The patent divides the media file into segments based on Group of Pictures (GOP) structures. Instead of caching the entire media file, only necessary segments are cached in memory while other segments are stored in file-based storage. This segmentation allows the system to maintain playback continuity for cached segments while avoiding Out Of Memory issues by not loading the entire file into memory.
Solution Approach 2:
The patent introduces a two-tier storage architecture combining volatile memory (RAM) and persistent file-based storage. By moving from a single-memory-dimension approach to a multi-dimensional storage hierarchy, the system can cache frequently accessed segments in fast memory while storing less frequently accessed segments in file-based storage, thereby reducing memory consumption while maintaining playback continuity.
2Manufacturing precision
If the entire media file is decoded for rewind playback, then playback quality is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary decoding and caching of media segments into GOP-based units during the initial playback. By pre-decoding and caching segments in advance, the system avoids the need to decode the entire file when rewind playback is requested, thereby reducing processing time while maintaining playback quality through selective caching of decoded segments.
Solution Approach 2:
The patent extracts and caches only the necessary GOP segments required for rewind playback rather than decoding and caching the entire media file. This extraction approach allows the system to maintain high playback quality for the extracted segments while significantly reducing the overall processing time by avoiding unnecessary decoding of unrelated portions of the media file.
3Manufacturing precision
If high resolution frames are cached, then playback quality is improved, but memory usage increases on mid-to-low-end devices
Solution Approach 1:
The patent applies local quality optimization by caching GOP segments at their original high resolution in memory while storing less critical or less frequently accessed segments at reduced resolution in file-based storage. This local quality approach ensures that the most important segments maintain high playback quality while reducing overall memory usage on mid-to-low-end devices.
Solution Approach 2:
The patent dynamically adjusts the resolution parameter of cached frames based on device capabilities and memory availability. For mid-to-low-end devices with limited memory, the system automatically reduces the resolution parameter of cached frames while maintaining acceptable playback quality, thereby reducing memory usage without completely sacrificing visual fidelity.
Data Source
AI summary
A media player providing real time rewind playback of a played media file having segments of frames. A last segment N of the played media file is cached and rendered on a device, such as a mobile device, then a previous segment N−1 is cached and rendered, and the process continues until there are no more segments of the played media file to cache and render. Only a segment of the played media file is cached at a time, rather than the whole media file, such that the played media file can be replayed on the fly.