Multicast Synchronization via Independent Frame Recoding
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Solution Overview
Problem
In multicast video technology, the existing methods for quick access to multicast sessions often result in unsynchronized data among terminals, leading to delayed video playback and reduced user experience, especially in applications like IPTV and video conferencing.
Innovation Solution
A synchronization method and apparatus that re-code frame multicast data unable to be independently decoded into data that can be independently decoded, allowing for the selection and transmission of suitable frame multicast data for initial playback, ensuring synchronous playback across terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If random access points are sent in a fixed short period to enable rapid video playback on new terminals, then access time delay is reduced, but coding, decoding and transmitting efficiency deteriorates due to the large size and coding time of random access points
Solution Approach 1:
The patent segments the video stream into two types of frames: random access points (key frames) that can be independently decoded, and non-random access points that depend on previous frames. By selectively sending only random access points in the multicast stream, the system enables terminals to quickly join and play video without transmitting every frame, thus reducing access delay while maintaining coding efficiency.
Solution Approach 2:
The patent performs preliminary action by pre-identifying and marking random access points in the video stream before multicast transmission. Terminals can independently decode these pre-identified key frames without needing to receive or process intermediate frames, enabling rapid video playback upon joining the multicast group.
2Loss of time
If different terminals receive different video random access points when accessing the multicast group at different times, then quick access is enabled, but data synchronization between terminals deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where terminals send access timing information to a control server, and the control server responds by calculating and distributing synchronized playback timing to all terminals. This feedback loop ensures that even though terminals join at different times, they all synchronize their video playback to the same timeline, maintaining data consistency across the multicast group.
Solution Approach 2:
The control server acts as an intermediary between terminals and the multicast stream. It receives timing information from terminals, calculates synchronized playback parameters, and distributes these parameters to ensure all terminals play back video data in sync, resolving the synchronization problem caused by different access times.
3Productivity
If the time interval between adjacent random access points is increased to reduce data volume, then coding efficiency improves, but playing delay between terminals increases
Solution Approach 1:
The patent changes the parameter of random access point interval from a fixed short period to a dynamically optimized interval. By carefully selecting and spacing random access points at optimal intervals, the system reduces the total data volume in the multicast stream (improving coding efficiency) while ensuring the intervals are short enough to minimize playback delay differences between terminals joining at different times.
Data Source
AI summary
Disclosed are a synchronization method and synchronization apparatus for multicast group quick access, and a terminal. The method includes: determining whether multicast data sent by a multicast server are frame multicast data that can be independently decoded, and re-coding the multicast data into frame multicast data that can be independently decoded when the multicast data are frame multicast data that cannot be independently decoded; selecting, according to a request from the terminal, frame multicast data for initial playing that can be independently decoded; and sending the selected frame multicast data for initial playing that can be independently decoded and subsequent multicast data to the terminal. The disclosure allows synchronous playing of multicast data on different terminals, thus improving terminal user experience.