Re: clarification on RME suggestions ...
Re: clarification on RME suggestions ...
- Subject: Re: clarification on RME suggestions ...
- From: John Lazzaro <email@hidden>
- Date: Fri, 21 Jun 2002 17:52:35 -0700
>
Jeff Moore writes:
>
>
[...]
>
>
The current Prefs Pane doesn't allow for that. It just lets you choose
>
the device. It doesn't know anything about channels or streams.
>
>
[...]
>
>
In Jaguar, there is a new property,
>
kAudioDevicePropertyPreferredChannelsForStereo, but there won't be a
>
GUI for this property. So there isn't a way to set it to something
>
other than the default, which is channels 1 & 2.
OK, so for the stereo case, once Jaguar arrives, the solution
would seem to be:
Check
kAudioHardwarePropertyDefaultOutputDevice
and then check
kAudioDevicePropertyPreferredChannelsForStereo
and then examine
kAudioDevicePropertyStreamConfiguration
to figure out where those two channels are in the device
stream configuration.
Which yields three pretty simple cases for applications to support:
[1] [2] // two mono streams
[1 2] // one interleaved stereo stream
[1 2 3 ...] // a multichannel interleaved stream, to which you
// write stereo to the first two channels
If kAudioDevicePropertyPreferredChannelsForStereo can return an
arbitrary contiguous pair, the split stream case (i.e.
[1 2] [3 4 5]
with a kAudioDevicePropertyPreferredChannelsForStereo of [2 3]) also
needs to be supported by an app. And depending on the level of
optimization the application code uses, [4 5] might need special case
code too.
This seems like a reasonable solution ... thanks for the info ...
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John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley
lazzaro [at] cs [dot] berkeley [dot] edu www.cs.berkeley.edu/~lazzaro
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