RE: [Discuss-gnuradio] Can't get input from sound card.

[Bahn William L Civ USAFA/DFCS]

> 
> > Subject: Re: [Discuss-gnuradio] Can't get input from sound card.
> > LRK
> > address@hidden
> >
> > On Sat, Mar 17, 2007 at 01:15:34AM -0600, Bahn William L Civ
> USAFA/DFCS
> > wrote:
> > >
> > > I still can't get any input from the sound card. I have installed
> GNU
> > > Radio on a completely different computer. The dial_tone.py program
> > > works. I get a flat line (it bounces around between -8e-5 and
+4e-5)
> > > when I run audio_fft.py in the oscilloscope mode.
> > >
> > I have not found a way to set these from GR and I have some
soundcards
> > which do show a 'rec' control and do not work. Best I can tell the
> > soundcard world is a 'black art' and there are no standards.
> >

I hate magical, mystery solutions - but here is what worked:

This is for FC5 and the GNOME desktop environment:

Select "Preferences-Volume Control". You should have a mixer panel with
two tabs - Playback and Capture. Select the Capture tab. What you see
appears to depend on the sound card you have, but you'll probably panels
for Line-In, CD, and Microphone. None of these are what you want (gee,
go figure that the 'Microphone' control has no control over the
microphone). What you probably will not see is a panel for 'Capture'. To
get that panel, go to "Edit-Preferences" and check the 'Capture' box.
There are three icons at the bottom - one to slave the two channels
together, one to mute the device, and one to toggle "audio capture from
Capture". You want to un-mute the device and select it for Capture. If
you just un-mute it, there appears to be some bleed through, but you
really need to select it for Capture.

So what's magical and mysterious about this? The fact that I had set it
up just this way and it didn't work. Then, when basically making random
changes to the options, it started working. So keep that in mind.