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.
> >
> > In the hopes of perhaps, possibly getting some kind of a response,
I'll
> > try to ask very specific questions.
> >
> > 1) Is the signal source for audio_fft.py supposed to default to the
> > sound card microphone?
> >
> > 2) If not, what is the default?
> >
> > 3) If not, can I tell it to use the sound card microphone?
> >
> > 4) If yes, how?
> 
> 
> I'm running FreeBSD and the sound cards are controlled by the 'mixer'
> command. There is a similar command in Linux. Maybe 'amixer'?
> 
> I have to select the input with the 'mixer', either mic or line. I
also
> have a control named 'rec' which sets the input volume level. The
latest
> versions of FreeBSD save the mixer settings across re-boots.
> 
> 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.
> 
> 
> Maybe someone can shed more light on this.

Thanks LRK, that helped at least some. In the GNOME GUI I found a mixer
under "Preferences-Volume Control". By un-muting the microphone I got it
so that the mike is now live (blow into it and you hear it at the
speaker) and selected it as the capture device. But the GNUradio apps
such as audio_fft.py still show no response.

So although I'm half a step closer, I still think I need at least the
basic answers to the above questions, namely:

1) Is the signal source for audio_fft.py supposed to default to the
sound card microphone?
2) If not, what is the default?
3) If not, can I tell it to use the sound card microphone?
4) If yes, how?

Thanks.