Sound input using mic / line in problem

I am trying to run the example file to capture some
signals. I plan to feed some slowly changing voltage signals through my
mic/line in audio input and use those along with the USRP signals (after
doing the necessary fractional resampling). I tried running the example
the following options

./ -I plughw:0,0 test.dat

The output says, “audio: using audio_alsa” and the program does nothing
else. Pressing Ctrl-C doesn’t terminate the program and I have to use
python” to kill it. The file size of test.dat remains at 0 bytes. I am
Ubuntu 8.04 and gnuradio r10529. gnuradio was built with gr-audio-alsa,
gr-audio-oss and gr-audio-jack. The sound module being used is

I also tried to use oss by changing audio_module = audio_oss in
~/.gnuradio/config.conf and end up getting the following error. The
remains the same regardless of using plughw:0,0 and hw:0,0

audio: using audio_oss
audio_oss_source: plughw:0,0: No such file or directory
Traceback (most recent call last):
File “./”, line 61, in
File “./”, line 49, in init
src = audio.source (sample_rate, options.audio_input)
File “/usr/local/lib/python2.5/site-packages/gnuradio/”,
299, in source
return _audio_oss.source(*args, **kwargs)
RuntimeError: audio_oss_source

Any ideas of what might be going on?


gr-audio-oss and gr-audio-jack. The sound module being used is

In my experience, there seem to be endless permutations of problems
with snd_hda_intel (“HD Audio”). Even in newer Linux releases like
Ubuntu 9.04. I don’t think I have a single machine on which
snd_hda_intel is trouble-free – including an HP Athlon64 desktop, a
Dell Atom netbook, and an Acer Atom netbook.

(which may or may not have anything to do with your problem.)


On Fri, Jul 3, 2009 at 1:05 PM, John G. [email protected] wrote:


Thanks for the pointer. Adding a line in /etc/modprobe.d/alsa-base which
specified the model of my computer helped (Dell Precision), more details
here However, the
inputs in ALSA don’t get correctly mapped to the actual physical inputs.
eg, the “Front Mic” on ALSA was actually the rear line-in. This only
the problem of being able to get the example program running without any
device busy errors or lockups. To be able to actually record sound, I
had to
install jack and play around with the settings for a bit. When using
gnuradio I also added audio_module = audio_jack to the gnuradio