Hello all, I'm working on a little app utilizing 'lasound' and I've got bassically what I want. However, somewhere there is a fault. Editing a random variable causes a segmentation fault. I've tried gdb but except it telling me where the application crashed (which I already knew) I did not get anything useful out of it. To minimize my own potential errors I have here below the example script from where I started (though I have removed some unnecessary stuff) and commented out the 'long *outvl' and '*outvl = -1'. Uncommenting, compile, and run this and I get a segmentation fault.
The original script is available at the following link: http://stackoverflow.com/questions/7657624/get-master-sound-volume-in-c-in-linux Can someone tell me where this is going wrong? Thanks in advance, Maarten #include <unistd.h> #include <fcntl.h> #include <alsa/asoundlib.h> /* Drawbacks. Sets volume on both channels but gets volume on one. Can be easily adapted. */ int audio_volume(long* outvol) { snd_mixer_t* handle; snd_mixer_elem_t* elem; snd_mixer_selem_id_t* sid; static const char* mix_name = "Fake"; static const char* card = "default"; static int mix_index = 0; // long *outvl; // *outvl = -1; int ret = 0; long pmin, pmax; snd_mixer_selem_id_alloca(&sid); //sets simple-mixer index and name snd_mixer_selem_id_set_index(sid, mix_index); snd_mixer_selem_id_set_name(sid, mix_name); if ((snd_mixer_open(&handle, 0)) < 0) return -1; if ((snd_mixer_attach(handle, card)) < 0) { snd_mixer_close(handle); return -2; } if ((snd_mixer_selem_register(handle, NULL, NULL)) < 0) { snd_mixer_close(handle); return -3; } ret = snd_mixer_load(handle); if (ret < 0) { snd_mixer_close(handle); return -4; } elem = snd_mixer_find_selem(handle, sid); if (!elem) { snd_mixer_close(handle); return -5; } long minv, maxv; snd_mixer_selem_get_playback_volume_range (elem, &minv, &maxv); fprintf(stderr, "Volume range <%i,%i>\n", minv, maxv); if(snd_mixer_selem_get_playback_volume(elem, 0, outvol) < 0) { snd_mixer_close(handle); return -6; } fprintf(stderr, "Get volume %i with status %i\n", *outvol, ret); /* make the value bound to 100 */ *outvol -= minv; maxv -= minv; minv = 0; *outvol = 100 * (*outvol) / maxv; // make the value bound from 0 to 100 snd_mixer_close(handle); return 0; } int main(void) { long vol = -1; printf("Ret %i\n", audio_volume(&vol)); return 0; } _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
