On Mon, 2013-04-15 at 21:20 +0200, Clemens Ladisch wrote: > jon wrote: > > Is the min value supposed to be negative or is the most common code > > everyone is using broken ? > > > snd_mixer_selem_get_playback_volume_range(elem, &min, &max); > > newvol= ( (long)volume * (long)max ) / (long)100 ; > > if ( snd_mixer_selem_set_playback_volume_all(elem,newvol) <0) > > Ignoring the min value is, of course, wrong. > > "Math is hard, let's go shopping!" > File a bug and suggest to go shopping here: > <http://git.alsa-project.org/?p=alsa-utils.git;a=blob;f=alsamixer/volume_mapping.c;hb=HEAD> > > Thanks :-) I had already hacked round the issue, not good at math though - it shows. Looks like the code you pointed at would offer a more progressive volume than this: // **************************************************** Raspberry Pi #ifdef RPI #ifdef ALSA #include <alsa/asoundlib.h> void set_volume(long volume) { long min, max, newvol; snd_mixer_t *handle = NULL; snd_mixer_selem_id_t *sid = NULL; const char *card = "default"; //const char *selem_name = "Master"; const char *selem_name = "PCM"; float vpercent, fnewvol; if (snd_mixer_open(&handle, 0) < 0) { printf("%s: set_volume() RPI - snd_mixer_open failed\n",PROGNAME); fflush(stdout); perror("snd_mixer_open"); } else { snd_mixer_attach(handle, card); snd_mixer_selem_register(handle, NULL, NULL); snd_mixer_load(handle); //snd_mixer_selem_id_alloca(&sid); snd_mixer_selem_id_malloc(&sid); snd_mixer_selem_id_set_index(sid, 0); snd_mixer_selem_id_set_name(sid, selem_name); snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid); if (elem == NULL) { printf("%s: set_volume() RPI - snd_mixer_find_selem failed()\n",PROGNAME); fflush(stdout); } else { snd_mixer_selem_get_playback_volume_range(elem, &min, &max); vpercent = (float)volume/100; fnewvol = (float)min + vpercent * ( (float)max - (float)min); newvol = (long)fnewvol; //printf("volume=%ld min=%ld max=%ld newvol=%ld\n",volume,min,max,newvol); fflush(stdout); if ( snd_mixer_selem_set_playback_volume_all(elem,newvol) <0) { printf("%s: set_volume() RPI - snd_mixer_selem_set_playback_volume_all() failed\n",PROGNAME); fflush(stdout); } } snd_mixer_close(handle); } } #endif // ALSA ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
