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Sample Rate: 44100 or 48000
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Sample Rate: 44100 or 48000


  • Subject: Sample Rate: 44100 or 48000
  • From: Marc Van Olmen <email@hidden>
  • Date: Sun, 14 Aug 2005 10:27:37 -0400

hi,

After I found the right device tried both Aurora and Decklink video card:

I'm using the call here below to get the device information:


aSize = sizeof(AudioStreamBasicDescription); BAIL_OSERROR(AudioUnitGetProperty( fOutputAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, &outputCoreAudioFormat, &aSize));


and it returns 44100 for Sample Rate.

But when I take the HALLab application it list as Nominal Sample Rate only 48000.

So I'm surprised by this result.

Questions:

1. Why is the device returning 44100 and not 48000?

2. Should I set my output samplerate to 48000?

3. What's the best way to set the correct sample rate.

================================

Unrelated question:

Is there a way to poll the audio device for his current time?

why:
I know that my rendercallback gives me the device time. but I was just wondering if I can poll for the device time with a API call. Because currently I'm using the Quicktime call back "ClockGetTime(fVideoOutputClockInstance,&aTimeRecord);" this works perfect on an Aurora video card. But the Blackmagic video card gives sometimes results back that are 0.004 seconds off the elapsed time then taking the CPU timing. 0.004 is a LOT in video. So I'm not sure that this call works reliable for Decklink cards,



regards,

mvo

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