Hello, just to finish this thread, a colleague of mine put me on the right track: timers. If you look at the alsa-lib timer example http://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2timer_8c-example.html , you see the timer interface being used to register on master timer ticks. The read loop simply waits on poll.
Actually, timer work on a variety of events, see http://www.alsa-project.org/alsa-doc/alsa-lib/group___timer.html , enum snd_timer_event_t . To register on specific events, you create a filter mask of your events ( 1 << event1 || 1 << event2 || ... ) and set it to your timer parameters with snd_timer_params_set_filter . In read loop of the timer example, you just need to use snd_timer_tread_t instead of snd_timer_read_t . In my case, I registered on the timer events SND_TIMER_EVENT_MSTART and SND_TIMER_EVENT_MSTOP and it works as expected. Regards, Thomas ________________________________________ From: Frank Thomas Sent: 04 June 2018 08:53:57 To: alsa-user@lists.sourceforge.net Subject: Get triggered when the device opens Hello, I'd like to apologise beforehand if I have not read enough documentation and/or source code to be posting here. Please do not hesitate to tell me to RTFM ☺ My application needs to get triggered when a mechanism any application is opening or closing a certain list of ALSA devices. It seems that ALSA hooks would be a way to do it. AFAIK I can only use a hook to trigger a function a in a pcm control plugins with certain arguments. I would need implement a control plugin that notifies my application for me and use a hook to trigger the trigger ☺ Is there another way, e.g. with the ALSA API, to get triggered on such events? Thanks in advance. Regards, Thomas Frank ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
