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Re: AudioTimeStamps in HAL IOProc & HW latency
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Re: AudioTimeStamps in HAL IOProc & HW latency


  • Subject: Re: AudioTimeStamps in HAL IOProc & HW latency
  • From: Jeff Moore <email@hidden>
  • Date: Wed, 27 Oct 2004 11:51:44 -0700

You have things correct. In an IOProc, in_buf_size is always equal to out_buf_size. I guess the documentation can't be all bad =)

On Oct 27, 2004, at 6:57 AM, Sven Behne wrote:

Hi,

I have a few questions regarding the input and ouput time stamps in the AudioDevice's IOProc, where the documentation and the CoreAudio header files are a little vague (at least to me).

Is the input time stamp (no matter wheter mSampleTime or mHostTime) the time when the driver receives the audio data from the hardware? If yes, this would mean input time stamp minus input hardware latency (kAudioDevicePropertyLatency) is the point in time when the (analog) audio signal was recorded (via mic/DI or whatever).
For the output this would mean, that the output time stamp is the estimate time when the driver will receive the data and the signal will be audible kAudioDevicePropertyLatency frames later?


If these assumptions are right so far, the minimum thru time for a device should be in_hw_latency + in_buf_size + in_safety_offset + out_buf_size + out_safety_offset + out_hw_latency?

Regards,

Sven

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--

Jeff Moore
Core Audio
Apple


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References: 
 >AudioTimeStamps in HAL IOProc & HW latency (From: Sven Behne <email@hidden>)

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