Re: Getting Volume Controls
Re: Getting Volume Controls
- Subject: Re: Getting Volume Controls
- From: bryan <email@hidden>
- Date: Mon, 20 Sep 2004 12:34:32 -0700
Thank you, Jeff. I eventually stumbled onto this fact :)
In the system audio settings, where you can select the between microphone and
line input, there is a "vu meter" that shows the input level. Can you tell me
the exact calculation used in this level display? Or if it is possible to get
the system to give me the input level directly?
Quoting Jeff Moore <email@hidden>:
> What you are missing is the fact that not all pieces of hardware have a
> master volume control, which is what you are asking about in your code.
> It is quite common for devices, like the built-in hardware on most
> Macs, to have individual channel volumes so you would need to ask for
> the volume on channel 1 and channel 2 as well as the master channel.
>
> On Sep 18, 2004, at 11:56 AM, bryan wrote:
>
> >
> > I am using the Java CoreAudio classes, and I want to be able to read
> > the
> > volume on the default input and output devices, but I am running into
> > problems:
> >
> > // query for the input device -- succeeds
> > AudioDevice device = AudioHardware.getDefaultInputDevice();
> >
> > // create a memory object to hold the Float32
> > CAMemoryObject propVal = new CAMemoryObject(4,true);
> >
> > // query for the volume -- fails with
> > kAudioHardwareUnknownPropertyError
> > device.getInputProperty
> > (0,AHConstants.kAudioDevicePropertyVolumeScalar,propVal);
> >
> > I have also tried to query for kAudioDevicePropertyVolumeDecibels with
> > the
> > same result.
> >
> > Any idea what I am missing?
> >
> > Thanks,
> > Bryan
> >
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> --
>
> Jeff Moore
> Core Audio
> Apple
>
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