Good, tight midi playback is pretty much unacheivable in Linux with the stock kernel due to scheduling jitter. Realtime kernel + 1000Hz timer is probably best, but you can improve things with a standard kernel by increasing the timer HZ setting of the kernel to a value around 1000Hz but that still means a recompile. The 'stock' kernels shipped by many linux distros are really, noticeably bad for MIDI - they have the timer clock set as low as 100Hz. -Pete > Hi. > > I use jackd as follows: > /usr/bin/jackd -v -R -P70 -dalsa -r48000 -p128 -n2 -D -Chw:0 -Phw:0 -Xraw > > Here's my output from alsa-info script: > http://www.alsa-project.org/db/?f=8b1149c838d952854b79008a7a9b1980bd3ba0ff > > I notice that when I record MIDI from my vDrums, the playback is never > quite right. It doesn't matter what sequencer (e.g. qtractor, > rosegarden, etc.) I use to play a midi file. > > I tried a little experiment: > 0) record some midi of my drumming > 1) use qtractor to send MIDI through my Midiman 1x1 USB midi interface > to the vDrum brain > 2) use ardour to record the audio output of the vDrum brain > 3) repeat steps 1 & 2 > 4) compare the waveforms of the resulting audio tracks > > I get notes that vary between the files by 30-40 ms. Incidentally, if > I bypass alsa and create a WAV file with timidity, it's spot-on > perfect. > > So I don't know if alsa sequencer is just broken or if there's some > configuration/tuning that I could do to improve this. > > Any input appreciated (helpful input preferred :) > > Thanks, > Steve > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by: > SourcForge Community > SourceForge wants to tell your story. > http://p.sf.net/sfu/sf-spreadtheword > _______________________________________________ > Alsa-user mailing list > Alsa-user@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/alsa-user > ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
