Sound input using mic / line in problem

GNU Radio
1

I am trying to run the audio_to_file.py example file to capture some
audio
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
with
the following options

./audio_to_file.py -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
“pkill
python” to kill it. The file size of test.dat remains at 0 bytes. I am
using
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
snd_hda_intel.

I also tried to use oss by changing audio_module = audio_oss in
~/.gnuradio/config.conf and end up getting the following error. The
error
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 “./audio_to_file.py”, line 61, in
my_top_block().run()
File “./audio_to_file.py”, line 49, in init
src = audio.source (sample_rate, options.audio_input)
File “/usr/local/lib/python2.5/site-packages/gnuradio/audio_oss.py”,
line
299, in source
return _audio_oss.source(*args, **kwargs)
RuntimeError: audio_oss_source

Any ideas of what might be going on?

Thanks,
Karthik

2

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

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.)

John

3

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

   John

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 HdaIntelSoundHowto - Community Help Wiki. However, the
inputs in ALSA don’t get correctly mapped to the actual physical inputs.
For
eg, the “Front Mic” on ALSA was actually the rear line-in. This only
solved
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
config.conf
file.

Karthik