Re: change default system output device
Re: change default system output device
- Subject: Re: change default system output device
- From: Jeff Moore <email@hidden>
- Date: Thu, 7 Jun 2007 11:23:21 -0700
Most likely, somebody else is changing the default device after you
are changing it. The Sound Prefs panel will do just this when the
"Play alerts and sound effects through:" pop-up menu is set to
"Selected sound output device". You can use a different application
that doesn't do this, like Audio MIDI Setup or HALLab, to see the
effect of your change.
BTW, you can find out about when this happens by installing a listener
on the property.
On Jun 7, 2007, at 9:22 AM, Kaan Erdener wrote:
I've written a small utility to show current / list all / change the
default system output device, and I've encountered something I don't
understand. My "show current device" stuff works fine, the "list all
devices" works fine, but the "change device" doesn't work as
expected. I don't see any errors, but what I want is to change the
system-wide output device, and that doesn't happen.
Here's what I'm doing:
// deviceIdData is char* that's set up elsewhere
AudioDeviceID deviceId = (UInt32) [[NSString
stringWithUTF8String:deviceIdData] intValue];
UInt32 size = sizeof(deviceId);
OSStatus err =
AudioHardwareSetProperty
(kAudioHardwarePropertyDefaultSystemOutputDevice, size, &deviceId);
if (err != noErr) {
printf("error\n");
}
If I use an invalid input value for deviceIdData, I can generate an
error, so that's good. If I use a valid value, I see no errors, and
subsequent checks for "show current device" show the device that I
just set. But when I open System Preferences, there is no change in
output device. What am I missing?
I could make several guesses as to what's going on, haven't found
much info about this behavior, so any and all help would be greatly
appreciated.
--
Jeff Moore
Core Audio
Apple
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