Linux Set ALSA master volume from C code
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Set ALSA master volume from C code
提问by trenki
I've been looking for a simple C code example to set the master volume of the ALSA mixer but could not find anything simple for this supposedly common operation.
I've been looking for a simple C code example to set the master volume of the ALSA mixer but could not find anything simple for this supposedly common operation.
I'm totally unfamiliar with ALSA, so making my own minimal example will take time. I would be happy if anyone could provide one.
I'm totally unfamiliar with ALSA, so making my own minimal example will take time. I would be happy if anyone could provide one.
采纳答案by trenki
The following works for me. The parameter volume is to be given in the range [0, 100]. Beware, there is no error handling!
The following works for me. The parameter volume is to be given in the range [0, 100]. Beware, there is no error handling!
void SetAlsaMasterVolume(long volume)
{
long min, max;
snd_mixer_t *handle;
snd_mixer_selem_id_t *sid;
const char *card = "default";
const char *selem_name = "Master";
snd_mixer_open(&handle, 0);
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_set_index(sid, 0);
snd_mixer_selem_id_set_name(sid, selem_name);
snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);
snd_mixer_selem_get_playback_volume_range(elem, &min, &max);
snd_mixer_selem_set_playback_volume_all(elem, volume * max / 100);
snd_mixer_close(handle);
}
