Greetings, If a C++ flowgraph containing an audio source (ALSA) is reconfigured during runtime, the application will crash with:
audio_alsa_source[hw:1]: 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_source(2) using ninputs=0, noutputs=2 Aborted Some time ago the same problem has been fixed for the audio_alsa_sink and the attached patch contains the very same fix for the audio_alsa_source. Alex
From 5096a92b5d4c03c1b7514802d569b7a8f1cb71c4 Mon Sep 17 00:00:00 2001 From: Alexandru Csete <oz9...@gmail.com> Date: Sun, 10 Jul 2011 23:31:27 +0200 Subject: [PATCH] Check pcm state before messing with hw_params (prevents crash when flowgraph is reconfigured at runtime). --- gr-audio/lib/alsa/audio_alsa_source.cc | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/gr-audio/lib/alsa/audio_alsa_source.cc b/gr-audio/lib/alsa/audio_alsa_source.cc index 4f0042b..2f4506f 100644 --- a/gr-audio/lib/alsa/audio_alsa_source.cc +++ b/gr-audio/lib/alsa/audio_alsa_source.cc @@ -217,8 +217,14 @@ audio_alsa_source::check_topology (int ninputs, int noutputs) unsigned int nchan = noutputs; int err; - // FIXME check_topology may be called more than once. + // Check the state of the stream // Ensure that the pcm is in a state where we can still mess with the hw_params + snd_pcm_state_t state; + state=snd_pcm_state(d_pcm_handle); + if ( state== SND_PCM_STATE_RUNNING) + return true; // If stream is running, don't change any parameters + else if(state == SND_PCM_STATE_XRUN ) + snd_pcm_prepare ( d_pcm_handle ); // Prepare stream on underrun, and we can set parameters; bool special_case = nchan == 1 && d_special_case_stereo_to_mono; if (special_case) -- 1.7.6
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