Re: kAudioHardwarePropertyDeviceForUID ???
Re: kAudioHardwarePropertyDeviceForUID ???
- Subject: Re: kAudioHardwarePropertyDeviceForUID ???
- From: Baron <email@hidden>
- Date: Fri, 20 Sep 2002 09:31:22 -0700
You are getting the expected results. Every time the device comes and goes,
it is going to have a different AudioDeviceID value. That's why you use the
UID in first place. Since it is a unique and persistent identifier across
processes and boots, you can always get the valid AudioDeviceID for the
device that you care about.
note: If you are using a USB device for example, it will have a different
UID for each USB port in which it is connected.
bob aron
--
CoreAudio Team
Apple Computer Inc.
>
Hi Folks,
>
>
I have been using the kAudioHardwarePropertyDeviceForUID AudioHardware
>
property to get the current audio device for a saved GUID reference. I am
>
absolutely sure that the device exists in the system and is unique. I use
>
the following code:
>
>
AudioValueTranslation avt = {&audioGUID,
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sizeof(audioGUID),
>
&fAudioDevice,
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sizeof(fAudioDevice)};
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UInt32 avt_len = sizeof(avt);
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char guidbuf[256];
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OSStatus result =
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AudioHardwareGetProperty(kAudioHardwarePropertyDeviceForUID,
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&avt_len, &avt);
>
>
>
I find that the first time I do this in a run of my app, it works fine. If I
>
make the device go away and come back I find that the call completes with no
>
error but the AudioDeviceID I receive is garbage. For example:
>
>
result = 0
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fAudioDevice = 79
>
>
But the actual device id for the GUID I am trying to get is 46.
>
>
So, is there some lifetime thing that I am missing here or is this a genuine
>
bug.
>
>
I have also submitted this as Radar #3056119
>
>
Best regards,
>
>
>
B.J. Buchalter
>
>
Metric Halo
>
M/S 601 - Building 8
>
Castle Point Campus
>
Castle Point, NY 12511-0601 USA
>
tel +1 845 831-8600
>
fax +1 603 250-2451
>
>
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>
>
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>
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>
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