Audio Video Delay Measurement Using Embedded Timestamps
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Solution Overview
Problem
Existing solutions for measuring delay between audio and video signals are complex and not lightweight, making them unsuitable for integration into various products without dedicated audio/video synchronization equipment, leading to lip-sync errors and quality issues in digital video and audio streams.
Innovation Solution
A system comprising a first time server referencing a GNSS signal, a transmission device embedding timestamps into audio and video signals, a receiver with a local time server synchronizing its clock, and a delay processor to measure absolute and relative delays between the signals, generating a synchronization signal to synchronize audio and video for playout on content-consuming devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial products are used to measure delay between audio and video feeds, then measurement accuracy is improved, but device complexity increases significantly
Solution Approach 1:
The patent uses timestamp copies embedded in audio and video signals to measure delay. Instead of complex dedicated measurement equipment, the system embeds time reference information (timestamps) directly into the media streams, allowing delay measurement through simple timestamp comparison at the receiving end. This copying of time reference information transforms a complex measurement problem into a simple data comparison task.
2Measurement precision
If dedicated audio/video synchronization equipment is used, then synchronization accuracy is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent creates a universal timestamp embedding mechanism that can be integrated into any audio/video transmission system. The time server and timestamp embedding functionality are designed to work with standard audio and video signals, allowing the same solution to be manufactured into different products without requiring product-specific dedicated synchronization equipment. This multi-functional approach enables easy integration across diverse applications.
3Difficulty of detecting and measuring
If timestamps are embedded in audio and video signals, then delay measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by embedding timestamps into audio and video signals at the transmission end before the signals are processed or transmitted. This pre-embedding of time reference information eliminates the need for complex real-time delay analysis during reception. The timestamps are prepared in advance and simply need to be extracted and compared at the receiving end, transforming a complex measurement task into a straightforward data retrieval and comparison operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a lightweight and simple method for measuring and synchronizing audio and video delays, effectively reducing lip-sync errors and improving the quality of digital video and audio streams by accurately determining and adjusting signal timing.
Implementation Method 1
a first time server configured to generate a first timestamp, wherein the first time server references a GNSS signal
Implementation Method 2
a delay processor provided and configured to extract the first timestamp from the video signal and the second timestamp from the audio signal and compare the first timestamp and the second timestamp to the local timestamp to measure absolute delay and relative delay
Data Source
AI summary
A system is provided for measuring delay between audio and video signals. The system includes a transmission device for embedding a video timestamp to a video signal based on at least one remote timestamp generated by a first time server; and for embedding an audio timestamp to an audio signal based on the at least one remote timestamp generated by a first time server. Moreover, a delay processor determines an absolute delay and a relative delay between the audio and video signals by comparing each of the extracted video timestamp and the extracted audio timestamp with a local timestamp generated by the second time server. A synchronization signal is generated based on the measured absolute and relative delays; and used to synchronize the audio signal with the video signal to generate a media playout signal.