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Audio Video sync with Core Audio Queue Services
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Audio Video sync with Core Audio Queue Services


  • Subject: Audio Video sync with Core Audio Queue Services
  • From: Stephen Thomas <email@hidden>
  • Date: Thu, 22 Oct 2009 09:31:23 +0530

Technology used: Core Audio Queue services. (I could have used HAL, but it seems much complicated than queue services.)

Requirement:
I need to know each time when a enqueued buffer gets played.

As per document, there is no direct way to know this using queue services.

Proposed solution:
Slice the audio data into smaller chunks of 32ms or less.
In the above scenario, when the buffer moves from audio queue buffer to playback buffer we get a notification.
The delay would be 32ms * (size of length of playback buffer). So always we have a audio lag of specified time. Which is tolerable as long as it is within the limit.
In most of the systems this worked fine. Except for one Mac book Pro. (Strange thing is in one more Mac book Pro with similar configuration it worked fine.)
To solve this, I have experimented by slicing the audio data to 8ms chunk. It solved the av sink issue.

But this do not seem to be viable solution. Because there is a possibility of playback queue size getting increased (and we do not know about the size). Which will fail the above solution.

Please suggest how to sink audio and video using core audio queue services.

Stephen
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