Re: Changing the system volume?
Re: Changing the system volume?
- Subject: Re: Changing the system volume?
- From: Jeff Moore <email@hidden>
- Date: Wed, 4 Jun 2003 11:46:27 -0700
You are best of using the volume properties of an audio device as found
in the HAL. The sample app, Daisy, in /Developer/Examples/CoreAudio/HAL
has code for doing it.
That said, you will really want to bone up a bit about how audio
devices are implemented on the system. The IOAudio family and the HAL
present devices to the system as they really are. This means that not
all devices have volume controls any more and the ones that do do not
necessarily provide their gain stages in the same locations. Again,
Daisy will help you visualize what's going on.
On Wednesday, June 4, 2003, at 09:24 AM, Eric Shapiro wrote:
Is there a snippet of code somewhere on how to change the system
volume?
I've been searching Apple's web site, usenet, and the core audio list
archives, but the only clues I see are that either
"IOAudioLevelControl::CreateVolumeControl()" or
"SoundComponentSetInfo(siHardwareVolume)" might be the right approach.
But no further documentation on the subject.
I need control the audio volume in MacOS X 10.2 from a C/C++
user-level Carbon/Mach-O application that will run with no real user
input. The program needs to be able to unmute the built-in speaker and
change the volume as needed. In the old MacOS days, there was a low
memory global to control the volume and later some system calls, but
neither of those work on MacOS X.
Thanks,
Eric Shapiro
--
Jeff Moore
Core Audio
Apple
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