Video Stream Synchronization via Clock Offset Compensation
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Solution Overview
Problem
Existing solutions for synchronizing video streams from multiple user devices in social media environments are inefficient due to network delays and variations, internal clock inaccuracies, and the impracticality of using external hardware, leading to asynchrony in live feeds.
Innovation Solution
A method involving the transmission of a system clock reference over a wireless short-range communication channel to user devices, calculation of clock offsets, and tagging video frames with timestamps to align capture times, enabling time synchronization of video streams across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If video streams are transmitted simultaneously from multiple user devices, then the live broadcast can be produced collaboratively, but network delays cause asynchrony in video streams
Solution Approach 1:
The system performs preliminary actions by having user devices send timing information (timestamps and clock offsets) ahead of the actual video data transmission. The server uses this advance timing information to pre-calculate expected arrival times and establish a reference timeline before video streams arrive, enabling synchronized playback despite network delays
Solution Approach 2:
The server acts as an intermediary that receives timing information from multiple user devices, calculates clock offsets relative to a reference device, and uses these offsets to synchronize video streams from different sources. This intermediary processing of timing data enables collaborative video production while maintaining synchronization
2Productivity
If clock synchronization is used with timestamps from internal clocks, then processing efficiency is improved, but clock drift and skew cause devices to go out of synchronization
Solution Approach 1:
The system implements feedback by having user devices send their timestamps and clock offset information to the server. The server uses this feedback to calculate the actual clock offset of each device relative to the reference device, then uses these calculated offsets to compensate for clock drift and skew in the video synchronization process
Solution Approach 2:
The system changes the time reference parameter from absolute timestamps generated by potentially drifting internal clocks to relative timestamps calculated using measured clock offsets. This parameter transformation converts unsynchronized absolute times into synchronized relative times, maintaining both processing efficiency and synchronization accuracy
3Measurement precision
If external hardware synchronization is used, then video stream synchronization accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The system replaces mechanical/physical synchronization hardware with an electronic/software-based solution. Instead of using external hardware synchronization devices, the patent uses network communication to exchange timing information and software algorithms to calculate and apply clock offsets, achieving synchronization without additional physical hardware
Solution Approach 2:
The system creates a virtual copy of the synchronization function that exists in professional hardware systems. By implementing the timing measurement and offset calculation logic in software, the patent replicates the synchronization capability of expensive hardware without requiring the physical devices, reducing complexity while maintaining functionality
Data Source
AI summary
A system clock reference is transmitted to user devices over a short range communication channel and used to calculated a clock offset. The clock offset is stored together with a user identifier in a server memory, from which the clock offset can be retrieved when receiving the user identifier together with a video stream of video frames tagged with respective timestamps. The timestamps are converted into capture times according to a system clock using the retrieved clock offsets. Video streams from multiple user devices thereby have video frames timestamped using a same clock reference and can be time aligned.