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Re: AudioTimeStamp in AURenderCallback
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Re: AudioTimeStamp in AURenderCallback

  • Subject: Re: AudioTimeStamp in AURenderCallback
  • From: "Dave O'Neill" <email@hidden>
  • Date: Mon, 30 Mar 2015 12:10:13 -0700
Old thread, but useful info.  I have measured the relationship between mHostTime and mSampleTime (on iOS), and it appears that for a timestamp in the render callback mHostTime represents the machine time of the last sample in the callback.  So to get the corresponding mach_time of the first sample in the callback (mSampleTime) you need to subtract (inNumberFrames * samplesToTicks) from mHostTime. 

On Wed, Oct 22, 2014 at 1:45 PM, Paul Davis <email@hidden> wrote:


On Wed, Oct 22, 2014 at 4:33 PM, Dave O'Neill <email@hidden> wrote:
Ok thanks, that makes sense.  If it's reset to zero at any point than it must refer to the first sample.  But I'm still confused about the relationship of .mHostTime.  It seems to be set to a future time that corresponds to the NEXT callback time, this is particularly confusing when trying to put a timestamp to a sample on an input callback (remoteIO mic input).  You would think that .mHostTime would be tied to .mSampleTime and that that time would be in the past for input samples.

as i mentioned, i could find nothing anywhere that defined these fields in a way that allowed me, as a host developer, to set them according to some thing that is well-understood. so much so that I do not even set mHostTime at all. if you find anything that usefully defines these fields, please let me know. 

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