Video Stream Timestamp Correlation via System Clock
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Solution Overview
Problem
Existing video capture devices face challenges in synchronizing video streams due to device clock drift, temporal distortion, and unreliable data transfer, especially when combining multiple streams for three-dimensional or multi-perspective video, which affects user experience.
Innovation Solution
A computerized method that receives video frames from capture devices, predicts timestamps based on a system clock, calculates skew values, and corrects frames to synchronize them with the system clock, thereby reducing temporal distortion and improving the quality of video streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If device clocks are used for timestamping video frames, then each capture device can independently timestamp frames, but clock drift causes temporal distortion and jitter in the video stream
Solution Approach 1:
The system continuously monitors the actual arrival times of video frames and compares them with expected timestamps. Based on this feedback, the system calculates skew values and applies corrections to subsequent frames, creating a closed-loop control system that compensates for clock drift and maintains synchronized timing across multiple capture devices
Solution Approach 2:
The system dynamically adjusts timestamp parameters by calculating skew values between device clocks and system clock. When skew exceeds a threshold, the system corrects timestamps by applying offset adjustments, effectively changing the timing parameters to compensate for clock drift without requiring hardware clock synchronization
2Adaptability or versatility
If multiple video streams are combined for three-dimensional or multi-perspective video, then enhanced video functionality is achieved, but synchronizing each stream requires extremely accurate timing that is difficult to maintain
Solution Approach 1:
The system introduces a system clock as an intermediary reference that mediates between multiple device clocks. Each video stream's timestamps are corrected relative to this common reference, ensuring that all streams are synchronized to the same time baseline. This intermediary clock acts as a coordinating mechanism that enables reliable multi-stream synchronization without requiring direct peer-to-peer clock synchronization between devices
3Ease of operation
If USB technology is used to transfer video frames, then device connectivity and data transfer are enabled, but timing accuracy of transferred frames deteriorates due to bus latency and processing delays
Solution Approach 1:
The system performs preliminary timestamping at the capture device using the device clock before frames are transferred via USB. This preliminary action records the exact capture time, allowing the receiving system to calculate expected arrival times and detect timing deviations caused by USB transfer delays, enabling subsequent correction of timestamp skew
4Manufacturing precision
If video processing operations are applied to video streams, then video quality enhancement is achieved, but frames may skew out of sync with the original timing
Solution Approach 1:
The system replaces mechanical clock synchronization mechanisms with a software-based timestamp correction system. Instead of requiring hardware-level clock synchronization between devices or processing systems, the invention uses software algorithms to calculate skew values and correct timestamps, substituting physical synchronization mechanisms with computational correction
Data Source
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AI summary
The methods described herein are configured to correlate frames of a video stream to a system clock. A correlator application receives a frame of a video stream from a capture device via a bus interface, the frame including start frame and end frame timestamps based on a device clock of the capture device. A second start frame timestamp and second end frame timestamp are predicted based on previously received frames and a system clock. A skew value of the frame is calculated based on differences between the start frame timestamps and the end frame timestamps. Upon the calculated skew value exceeding a skew threshold, the frame is corrected to correlate to the predicted start frame and end frame timestamps. The corrected frame is then provided for display. Correcting timestamps of video stream frames in the described manner reduces jitter and enables accurate synchronization of multiple video streams.