Re: [LAU] qtractor crashes (was: the defacto host for lv2)

I think I figured out what was causing the recent odd-behavior in qtractor (which has otherwise been stable enough to use as my main DAW). The problem was operator error and not qtractor. I had recently enabled the high-res timer and had accidentally set "View->Options->MIDI->Playback->Queue timer (resolution)" to "PCM Playback 1-0-0. (slave)" instead of ""PCM Playback 2-0-0. (slave)"... this caused the MIDI to go all wonky, and caused various freezes when making changes to the MIDI configuration. The problem is that jack is not talking to "playback 1-0-0" it is running on "playback 2-0-0" ... I finally figured this one out because qtractor would occassionally start rolling (as if play got clicked) simply by starting up the program. That's when I started investigating the value of the midi queue timer and found the erroneous setting. Previously, in thread "Is ALSA using hrtimer?" I asked about these settings... I guess I found out the hard way what happens when you set to the wrong value! For those that have an HRtimer, should the queue timer be set to "HR timer (1000000000 hz)"? "(default)" or slaved to the specific soundcard that jack is managing? http://linuxaudio.org/mailarchive/lau/2010/5/31/169505 .................. BTW, now that I've enabled hr timer, I notice that qtractor 's View->Options->MIDI->Playback has an entry for "Queue timer (resolution): [ (default), system timer (1000 Hz), HR timer (1000000000 hz), PCM Playback 0-0-0. (slave), PCM Playback 0-0-1 (slave), ... ]" What happens if I use "HR timer" instead of "(default)" or a specific PCM slave, when recording/playing back audio clips ? Does "PCM playback (slave)" mean the audio sample-clock is sync'd to the midi clock, or vice-versa? And if snd-hrtimer is available, wouldn't both audio and midi be using the same clock? (per Grant's comment ''CONFIG_SND_HRTIMER says: "ALSA uses the hrtimer as a precise timing source. The ALSA sequencer code also can use this timing source."'' ) W/r/t qtractor, does (default) "do the right thing" or should I be choosing a specific option based on use? I guess I'll find out... ................... -- Niels http://nielsmayer.com PS: to prevent this error in the future, would it be possible to suppress incorrect values from the choices presented for "queue timer (resolution)" ... for example don't allow user to select "PCM Playback 0-0-0 (slave) if that is not the device being managed by Jack.