Re: How to check if a system has an audio input?
Re: How to check if a system has an audio input?
- Subject: Re: How to check if a system has an audio input?
- From: William Stewart <email@hidden>
- Date: Tue, 28 Sep 2004 15:31:25 -0700
Title: Re: How to check if a system has an audio input?
What you are doing is correct... The “problem” is that AUHAL is an AU that can be used for either/or/both input and output, so it will always have a device that it is using...
Another way to do this with the AUHal unit is to get the format for the input scope on element 1 (this is where the input side of the device lives) - if that returns an error, you can assume that you have no input capability on the device currently being used by the AUHAL unit
Bill
On 28/9/04 12:15 PM, "Rolf Nilsson" <email@hidden> wrote:
Hi,
I'm trying out the "afrecord" example in the /CoreAudio/Services/AudioFileTools folder.
That example uses the default audio input.
Some computers does not come with a built in audio input.
How do I detect that a system does not have an audio input?
Even if there is no audio input, the following does not return an error:
// Get the Current Input Device ID
// this should be done only after IO has been enabled on the AUHAL.
propSize = sizeof(mInputDevice.mID);
XThrowIfError(AudioUnitGetProperty(mInputUnit,
kAudioOutputUnitProperty_CurrentDevice,
kAudioUnitScope_Global,
0,
&mInputDevice.mID,
&propSize), "failed to get current audio input device ID");
So I tried kAudioDevicePropertyDeviceIsAlive:
propSize = sizeof(UInt32);
UInt32 isAlive;
XThrowIfError(AudioDeviceGetProperty(mInputDevice.mID,
0,
true/*isInput*/,
kAudioDevicePropertyDeviceIsAlive,
&propSize,
&isAlive), "failed to check if the device is alive");
This one fails if there is no audio input. So this kind of works for my purpose but my feeling is that there should be a better way?
Thanks for any help
Rolf Nilsson
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