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AudioQueue latency problem
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AudioQueue latency problem


  • Subject: AudioQueue latency problem
  • From: Stefan Agamanolis <email@hidden>
  • Date: Sun, 9 Mar 2008 23:58:53 +0000


Hello,

I have written a super-simple 'audio conference' program in C that uses AudioQueue to record linear PCM audio, send it over the network, and play it back on a different computer.

The problem is latency -- even though I set the AudioQueue buffer size equivalent to 1/20th of a second of audio, my AudioQueue callbacks are getting called in spurts every second or so, so I don't get to touch the audio coming in from the microphone until quite long after it was spoken.

This periodic spurt of callbacks is also happening in the simplified case of just recording to a file, or playing back from a file.

It's as if the layer under AudioQueue is using a much longer buffer.

For the heck of it, I tried using AudioDeviceSetProperty() to set kAudioDevicePropertyBufferSize to something very low, and this did not help.

Is there something I have missed or is AudioQueue not the right interface to use for this kind of low-latency application? Any suggestions?

Thanks so much to anyone who can help!

-Stefan Agamanolis

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