I'm using a Mac Mini, Mac OS X 10.6.7, GarageBand, and a USB webcam/mic combination. Under "Audio Devices" in the Audio MIDI Setup program I have the following devices listed:
Built-in Output ("Use this device for sound output" is selected)
Unknown USB Audio Device ("Use this device for sound input" is selected)
At the moment my microphone is working just fine. The mic is picking up my voice correctly and I can record it using GarageBand. The problem is that it won't stay that way, and it takes me a very long time to get it working in the first place.
The devices are always listed correctly in the audio window. Audio MIDI Setup consistently recognizes that I have a USB Audio Device plugged into my Mac. In GarageBand, this is reflected under the Voice section in the "Input Source" dropdown menu. I verify that the input source is correctly set to the USB mic, and the output source is correctly set to my headphones. I verify that the Monitor dropdown box is set to "On" or "On (no feedback protection)".
However, the mic simply does not pick up any signal sometimes. There is no sound whatsoever. GarageBand's volume indicator for the input source, to the right side of the Measures/Bar/Beat box, will show no green marks if I speak into the mic. When this happens, I have to just fiddle with it for a long time until I get it working again. I try restarting, I try changing settings, etc. I've gotten it working as both a plain "Unknown USB Audio Device", and as an "Aggregate Device".
Once I get it working it stays up for hours. I can happily record vocals. Eventually though, it stops working all by itself. I just leave the mic plugged in and GarageBand running, and when I come back to it the mic is no longer able to pick up sound.
As far as I can tell, the issue is not with GarageBand. I've had the same problem using a full DAW program. I use my webcam/microphone with Photo Booth, and it works flawlessly, so the hardware is functioning. When I get it working with an audio program, it works fine -- clear sound, etc. I suspect the issue is with Audio MIDI Setup.
I recently ordered a copy of Logic Studio and I'd like to create complete songs including vocals using my Mac, so this is rather frustrating. Anyone having similar issues? Any help is appreciated.