I am working on an app which must change the configuration for sample rate on
the fly. I have produced code which seems to work. However, for some
reason, the app doing capturing runs only for about 2 seconds after capturing
begins, at which point the app crashes with a segfault. This is due to the
sampling, and in fact changing of the hwparams because if I comment out the
code which does that, I am able to sample continuously, which does not
satisfy my needs.
The code attached executes flawlessly. However, approximately two seconds
after executing it, I get teh segault with no explanation.
I am using the plughw device so as to allow a lot of this stuff to happen in
software for me.
I would appreciate any suggestions or refferences that you can point me to.
Garrett Kajmowicz
[EMAIL PROTECTED]
Initial initialization code for the device:
std::cout << "Initializting capture device\n";
stream = SND_PCM_STREAM_CAPTURE;
pcm_name = strdup("plughw:0");
snd_pcm_hw_params_alloca(&hwparams);
int retval;
int retdir;
if ((retval = snd_pcm_open(&pcm_handle, pcm_name, stream,
SND_PCM_NONBLOCK))
< 0) {
return;
}
if (snd_pcm_hw_params_any(pcm_handle, hwparams) < 0) {
return;
}
if (snd_pcm_hw_params_set_access(pcm_handle, hwparams,
SND_PCM_ACCESS_MMAP_INTERLEAVED) < 0) {
return;
}
if (snd_pcm_hw_params_set_format(pcm_handle, hwparams,
SND_PCM_FORMAT_S16_LE) < 0) {
return;
}
retdir = 0;
snd_pcm_hw_params_set_rate_near(pcm_handle, hwparams, 16000, &retdir);
if (snd_pcm_hw_params_set_channels(pcm_handle, hwparams, 1) < 0) {
return;
}
if (snd_pcm_hw_params(pcm_handle, hwparams) < 0) {
return;
}
The code section used to change the settings is as follows:
The stream, pcm_handle and the hwparams are teh same objects
as above;
global object
if(snd_pcm_drop(pcm_handle)<0){
std::cout << "PCM drop failed\n";
}else{
std::cout <<"PCM drop succeded\n";
}
if(snd_pcm_close(pcm_handle)<0){
std::cout << "PCM close failed\n";
}else{
std::cout << "PCM close succeded\n";
}
std::cout << "Opening PCM device" << std::endl;
if (snd_pcm_open(&pcm_handle, pcm_name, stream,
SND_PCM_NONBLOCK) < 0) {
std::cout <<"pcm_open failed\n";
return;
}else{
std::cout << "PCM open succeded\n";
}
if(snd_pcm_hw_params_any(pcm_handle, hwparams) < 0){
std::cout << "Error setting snd_pcm_hw_params_any";
}else{
std::cout << "Succeded setting params_any\n";
}
if(snd_pcm_hw_params_set_access(pcm_handle, hwparams,
SND_PCM_ACCESS_MMAP_INTERLEAVED)<0){
std::cout << "Error setting access mode\n";
}else{
std::cout << "Succeded setting access mode\n";
}
if (snd_pcm_hw_params_set_channels(pcm_handle, hwparams, 1) <
0) {
return;
}else{
std::cout <<"Channels set for recording\n";
}
std::cout << "Setting sample rate\n";
retdir=0;
std::cout << "Sample rate set to: " <<
snd_pcm_hw_params_set_rate_near(pcm_handle, hwparams, currentSampleRate,
&retdir) << std::endl;
std::cout <<"Setting data format\n";
//SNIP - doing a lot of comparisons to see what data format to
select.
//Sample code:
snd_pcm_hw_params_set_format(pcm_handle, hwparams,
SND_PCM_FORMAT_U8);
//End of SNIP
if (snd_pcm_hw_params(pcm_handle, hwparams) < 0) {
std::cout << "***Error setting playback HW params";
return;
} else{
std::cout << "Update of hwparams succeded\n";
}
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