Audio Video Synchronization via Timestamp Buffering

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Solution Overview

Problem

Existing methods for synchronized recording of audio and video streams face challenges in maintaining synchronization due to differing compression rates and loss of timing information during the encoding process, leading to out-of-sync streams.

Innovation Solution

An audio counter is used to increment a counter value with each audio signal, and the current counter value is recorded using a time stamp buffer when a video frame is received, allowing video signals to be time-stamped relative to the audio clock, ensuring accurate synchronization during multiplexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If audio and video signals are compressed separately using independent compressors, then compression efficiency is improved, but synchronization between audio and video streams deteriorates

Engineering Contradiction:

Improvecompression efficiencyVSAvoidsynchronization accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A timestamp generator acts as an intermediary device that receives both audio and video signals and generates synchronization timestamps. This mediator ensures that even though the audio and video compressors operate independently, the timestamp information allows for accurate resynchronization during multiplexing, thus resolving the contradiction between independent compression efficiency and synchronization accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If timing information is not preserved during compression, then compression flexibility is improved, but synchronization reliability deteriorates

Engineering Contradiction:

Improvecompression flexibilityVSAvoidsynchronization reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The timestamp generator performs preliminary action by capturing and recording timing information at the moment of signal generation, before the signals enter the compression process. This preliminary timestamping preserves synchronization data even though the compressors operate independently and may alter signal timing, thus maintaining both compression flexibility and synchronization reliability.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If audio and video signals are multiplexed without timestamp synchronization, then multiplexing speed is improved, but recording accuracy deteriorates

Engineering Contradiction:

Improvemultiplexing speedVSAvoidrecording accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The timestamp generator provides feedback information in the form of synchronization timestamps to the multiplexer. This feedback mechanism allows the multiplexer to accurately align audio and video streams during multiplexing without significantly reducing multiplexing speed, thus resolving the contradiction between multiplexing speed and recording accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7634005B2Method and apparatus for synchronized recording of audio and video streams

Publication Date: 2009.12.15 XUESHAN TECH INC

AI summary

A method for synchronized recording of audio and video signals is provided. The video signals are grouped into a plurality of video frames. The method comprises the steps of incrementing a counter value of an audio counter when an audio signal is received; and recording the current counter value of the audio counter when a video frame is received.