29 Jan
2013
29 Jan
'13
9:39 a.m.
Muffinman wrote:
I'm trying to poll mixer events in Alsa using C.
I've used the following
functions within an infinite while loop:
...
snd_hctl_poll_descriptors(hctl, poll_fds, 1);
You are supposed to call snd_hctl_poll_descriptors_count() to get the
number of descriptors.
if (poll_fds[0].revents & POLLIN)
You are supposed to call snd_hctl_poll_descriptors_revents() to get the
events from the descriptors.
While I can get the first mixer event fine, in all
subsequent rounds,
both snd_hctl_wait and poll always return immediately.
You should call snd_hctl_handle_events() to read all the events.
However, calling snd_hctl_handle_events here never
returns
and I can't quite figure out why.
See amixer/amixer.c in the alsa-utils package for an example.
"amixer events" is undocumented for some reason; but does it work?
Regards,
Clemens