On Fri, 16 May 2008, Ashwin Chandra wrote:

Hello,

I am having an issue with the Alsa mixer. Currenty I have a function that gets the volume via snd_mixer_selem_get_playback_volume. This function works fine to get the last-set volume if my application is setting the volume. However if I change the volume using an outside source, such as alsamixer or gnome-volume-control and then I run the above function, the old volume that my application had set last is returned.

Now I edited amixer's source code to put a while(1) around the same functions (the snd_mixer_selem_get_playback_volume), and it too does not get the correct volume if set from an outside source. Alsamixer on the other hand seems to work find, but I am not quite sure how they do it. I thought maybe I had to reinitialize the alsa interface (ie. snd_mixer_close...and then open, attach, register, etc), but it doesn't seem that alsamixer does that.

Does anyone have any suggestions about what I can do to get the correct volume if set by an outside source??

snd_mixer_handle_events() is function which updates changed controls. Values are cached.

Jaroslav

----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.