2010/2/23 Clemens Ladisch clemens@ladisch.de
Lennart Poettering wrote:
On Sun, 21.02.10 12:01, Raymond Yau (superquad.vortex2@gmail.com) wrote:
However Simple Mixer API cannot know the subdevice number , you have to
use
control API ( the lower level API used by Simple Mixer API )
Unfortunately there is no way from the simple mixer to the lower level mixer.
From the check_unplugged function in alsa-utils/alsamixer/mixer_widget.c:
err = snd_mixer_get_hctl(mixer, mixer_device_name, &hctl); if (err >= 0) ctl = snd_hctl_ctl(hctl);It would be great if the smixer would include some API that gives me a hint to which device/subdevice a specific snd_mixer_elem_t belongs to.
Often, there is no 1:1 correspondence between mixer elements and PCM devices. Only mixer controls with interface PCM (not MIXER) have (sub-) device numbers, and at the moment this is used only for controls that are associated with the streams of hardware-mixing-capable cards.
Getting information about the mixer layout (like the nodes reported by HDA and USB devices) is on the TODO list; the only reason it isn't being implemented is lack of time.
Regards, Clemens
for hda , Since PA server open pcm device , so it still can use
snd_mixer_selem_id_set_index(sid, snd_pcm_info_get_subdevice(pcm_info));
pavucontrol still can query PA server to get the sudevice numer whenever PA resum from suspend
But gnome volume control has no way to know which application open which subdevice