Audio-Video Clock Synchronization Using Video Rate Feedback
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Solution Overview
Problem
Conventional audio and video systems experience synchronization drift between audio and video tracks, leading to noticeable artifacts and unsynchronized playback, which existing methods fail to adequately address.
Innovation Solution
A method that synchronizes audio and video clock signals by comparing a system video signal with a determined mathematical relationship to produce an adjustment signal, updating the system video reference signal, and using a reference clock to eliminate frequency errors, ensuring zero error synchronization across all system components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional crystal based timing reference signals are used to provide global clock reference, then the system has simple timing reference management, but audio and video clocks drift apart causing synchronization loss
Solution Approach 1:
The patent implements feedback by continuously monitoring the synchronization status between audio and video clocks and dynamically adjusting the video clock rate. The system measures the drift between audio and video timestamps and uses this information to generate correction signals that adjust the video clock frequency, ensuring continuous synchronization without manual intervention.
Solution Approach 2:
The patent changes the video clock rate parameter dynamically based on measured synchronization drift. By adjusting the video clock frequency in real-time according to the detected drift between audio and video tracks, the system maintains accurate synchronization. This involves modifying operational parameters (clock rate) rather than changing the fundamental system architecture.
2Reliability
If frame dropping or repeating techniques are used to compensate for drift, then synchronization is maintained, but noticeable artifacts are introduced to the user
Solution Approach 1:
The patent performs preliminary action by proactively adjusting the video clock rate before significant drift occurs. By continuously monitoring the relationship between audio and video clocks and making preemptive adjustments to the video clock frequency, the system prevents synchronization errors from accumulating to levels that would require frame dropping or repeating as corrective measures.
Solution Approach 2:
The patent replaces the mechanical approach of frame dropping or repeating with an electronic clock rate adjustment mechanism. Instead of manually inserting or removing frames from the video stream, the system uses digital signal processing to adjust the video clock frequency, thereby maintaining synchronization through temporal scaling rather than frame manipulation.
3Ease of operation
If independent crystal clocks are used for audio and video subsystems, then each subsystem operates autonomously, but drift between audio and video tracks occurs
Solution Approach 1:
The patent merges the timing control of audio and video subsystems by establishing a master-slave relationship between the two clock systems. While the audio clock operates autonomously as the master reference, the video clock is enslaved to the audio clock through continuous rate adjustment based on synchronization feedback. This maintains operational independence of individual subsystems while ensuring their temporal coordination.
Data Source
AI summary
Provided herein is a method for synchronizing audio and video clock signals in a system. The method includes comparing, within a comparison module, a system video signal with the determined mathematical relationship to produce an adjustment signal. A system video reference signal is updated with the adjustment signal to produce an updated intermediate signal.