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Detecting dropouts?
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Detecting dropouts?


  • Subject: Detecting dropouts?
  • From: Jim Dolan <email@hidden>
  • Date: Mon, 25 Mar 2002 12:03:50 -0500

Hi -

I have a method that keeps track of the sample position from IOProc to
IOproc callbacks to ensure that there is no dropouts.

For example:
During the input IOProc I store the inInputTime.mSampleTime value. During
the next IOproc I add the buffer size in samples (adjusted for interleaving)
to the stored value. This should give me the new inInputTime.mSampleTime
value. In general this calculation seems accurate and works much of the
time. If the calulation does not match, meaning the (old_mSampleTime +
buffersize > current_mSampleTime ) I am assuming there is a gap in the
stream. Is this a valid assumption? The kAudioDeviceProcessorOverload is
never triggered. If my assumtion is correct what can I do to avoid this
situation? If I am not calculating correctly - how can I tell?

Can I safely assume that each time the record IOProc is called that samples
have not been dropped evn if the sampletimes do not match up?

The current buffer size I am using is 1024 bytes - Would making this
smaller or larger help? I need to ensure that the sample stream is pristine
ie: NO LOST SAMPLES on record or playback!!!!!!!!!

Thanks for your help
Jimmy D.
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    • Re: Detecting dropouts?
      • From: Jeff Moore <email@hidden>
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