Real-time Key Frame Generation for Media Playback
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Solution Overview
Problem
Media data streams with low or no key frames experience choppy trick-mode playback and compatibility issues with certain decoders, as they rely on key frames for high-speed playback and fast-forward/rewind functions, leading to suboptimal user experience.
Innovation Solution
A method for real-time generation of key frames in a media data stream, where a media server decodes and re-encodes media data to increase key frame frequency, enabling improved trick-mode and normal playback functionality by generating key frames upon request from a media receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If key frame density is decreased to reduce bit rate and file size, then compression efficiency is improved, but trick-mode playback quality deteriorates becoming choppier
Solution Approach 1:
The system performs preliminary decoding of predictive frames to generate key frames in advance of playback. When a trick-mode operation is requested, pre-decoded frame data is available to rapidly generate key frames without real-time decoding delays, ensuring smooth playback while maintaining low bit rate in the original stream.
Solution Approach 2:
The system introduces an intermediary buffering layer that stores decoded frame data between the compressed stream and the playback output. This buffer acts as a mediator, allowing the system to reconstruct key frames on-demand from stored decoded data without requiring them to be present in the original compressed stream.
2Reliability
If key frame frequency is increased to improve trick-mode playback, then playback smoothness is improved, but file size and bit rate increase
Solution Approach 1:
The system decodes frames preliminarily and stores them in a buffer before playback. When trick-mode operations are requested, key frames are generated on-demand from this pre-decoded data rather than being stored in the original stream, achieving smooth playback without increasing file size.
Solution Approach 2:
The system uses its own decoded frame buffer to service trick-mode playback requests, generating key frames from previously decoded predictive frames. This self-service approach eliminates the need for additional key frames in the compressed stream, maintaining file size while improving playback quality.
3Loss of energy
If media streams are encoded with no key frames to minimize bit rate, then compression is maximized, but decoder compatibility and playback functionality are lost
Solution Approach 1:
The system introduces an intermediary key frame generation layer between the compressed stream and decoder. This intermediary component reconstructs key frames from decoded predictive frames when needed, acting as a mediator that enables full decoder compatibility and trick-mode functionality without requiring key frames in the original compressed stream.
Solution Approach 2:
The system implements self-service key frame generation by using its own decoding capabilities to create key frames on-demand from predictive frames. This eliminates dependency on pre-encoded key frames in the stream, maximizing compression while ensuring compatibility with decoders that expect key frames for proper operation.
Data Source
AI summary
The real-time generation of key frames in a media data stream is disclosed. One embodiment provides a method of processing encoded media data comprising receiving a request to play back the encoded media data from a media receiver, generating one or more key frames from the encoded media data, and sending the generated key frame or key frames to the media receiver. The key frames are generated by decoding the media data, and then encoding the key frames from the decoded media data. In this manner, a frequency of key frames in a media data stream may be increased to improve trick mode and 1× playback.