Re: Problem with Alesis MultiMix 8 USB 2.0 and kAudioDevicePropertyStreamConfiguration
Re: Problem with Alesis MultiMix 8 USB 2.0 and kAudioDevicePropertyStreamConfiguration
- Subject: Re: Problem with Alesis MultiMix 8 USB 2.0 and kAudioDevicePropertyStreamConfiguration
- From: email@hidden (Stefan Haller)
- Date: Wed, 29 Aug 2007 21:48:43 +0200
- Organization: Ableton
Jeff Moore <email@hidden> wrote:
> > Here's what happens: we query the input side of the device for
> > kAudioDevicePropertyStreamConfiguration, it returns one buffer with 10
> > channels, which is what we expect. Then we set the sample rate
> > (kAudioDevicePropertyNominalSampleRate, isInput = true), and after
> > that we query kAudioDevicePropertyStreamConfiguration again; this time
> > it returns one buffer with 0 channels (and 0 mDataByteSize). This
> > strikes me as a driver bug; I can't quite imagine what we might be doing
> > wrong here.
> >
> > Then we start the device, and in the IO proc we get the expected
> > buffer list (one buffer with 10 channels), which doesn't match what the
> > last query of kAudioDevicePropertyStreamConfiguration had returned.
> >
> > Any ideas?
>
> This sounds like you are asking the HAL for the stream configuration
> in isolation and are getting an intermediate state of the device. Are
> you waiting for the notifications from the HAL about things changing
> or just assuming that your change took place after setting the sample
> rate?
We are not waiting for notifications, we are simply making synchronous
calls from the main thread. (We don't get a notification for
kAudioDevicePropertyStreamConfiguration, btw.)
We never had any problems doing it this way with any other audio device.
--
Stefan Haller
Ableton
http://www.ableton.com/
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