Marcus, this is a problem with the gnuradio/gr-audio-alsa/src/audio_alsa_source.cc. I ran into a few weeks ago and i managed to find a quick and dirty fix for.
I'm assuming that you're stopping the flow graph and restarting it
again. if you look into the "check_topology" method. There's a FIXME
there, what I beleieve is happening, is that when you try to restart
the flowgraph after stopping it GNU Radio is trying to reset your
sound card and it thinks that it's in a corrupt state.
My fix was to add a "static bool" variable that skips the
"snd_pcm_hw_params(d_pcm_handle, d_hw_params);" function call. the
flag is "static" just so you can detect your first entry. After that
run make and make install and things should work fine.
al
-----Original Message-----
From: Marcus D. Leech <address@hidden>
To: Discuss-gnuradio <address@hidden>
Sent: Sat, Oct 23, 2010 4:17 pm
Subject: [Discuss-gnuradio] audio_alsa: problem with "valve" at head of audio_alsa sink sub-graph
In my application I have a sub-graph that terminates an an audio_alsa sink.
At the "head" of this sub-graph, I've placed a valve, so that I can turn
off data being
copied to the audio_alsa sink.
When this valve transitions from "closed" (data flowing) to "open" (data
*not* flowing), it provokes
the following error in audio_alsa_sink:
audio_alsa_sink[plughw:0,0]: snd_pcm_hw_params failed: File descriptor
in bad state
terminate called after throwing an instance of 'std::runtime_error'
what(): check topology failed on audio_alsa_sink(1) using ninputs=1,
noutputs
Am I being an idiot here? Should this work? If not, why not?
Further, there's a "OK to block" parameter for an audio_alsa_sink. What
does it do?
--
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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