Re: audioqueue tiing w. audiotimestamps (again)
Re: audioqueue tiing w. audiotimestamps (again)
- Subject: Re: audioqueue tiing w. audiotimestamps (again)
- From: Jean-Daniel Dupas <email@hidden>
- Date: Thu, 12 Aug 2010 16:53:47 +0200
Le 12 août 2010 à 16:46, Robert Carroll a écrit :
> Hi,
>
> I have posted about this issue a few times.
>
> So far, attempting to control the playback start times of 3 or 4 audioqueues by setting independant audiotimestamps in the AudioQueueEnqueueBufferWithParameters
> is not working.
>
> I am using hosttime with the hosttime valid flags set in the sudiotimestamps. The times are derived form mach_absolute_time following some sample code originally from Doug Wyatt. The original code to get the host time has been re-written to be in Objective-C, but returns matching values to the sample code, so I don't think there is a problem with the times being set.
>
> Is there a fundamental flaw in using this approach? ie. I set times at one second intervals in the time stamps, enqueue the buffers with those timestamps are parameters, then trigger playback by sending a notification to all three or four queues? As I understand the documentation, this should cause them to play in sequence starting 1 second apart, however they all just play loosely at once, the same playback I get if I pass NULL for the audiotimestamp in the enqueue buffer call, or when I was just calling AudioQueueEnqueueBuffer.
>
> Any suggestions would be greatly appreciated.
>
AFAIK, AudioQueueEnqueueBufferWithParameters does not support host time, but only sample time relative to queue start time.
If you want to sync many queue, you can use host time in AudioQueueStart() to define a precise start time. Then you can schedule buffer relative to this time.
-- Jean-Daniel
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