On Wed, Mar 24, 2010 at 11:06:43AM +0100, Ralf Mardorf wrote: > At the > moment Linux on my computer and on computers of around 30 other people I > know can't use hardware MIDI equipment because of MIDI jitter. On the > same machines there is less jitter for Windows, so using Windows would > solve this problem for most of them.
This made me curious, and as I rarely use MIDI (just to play piano using Linuxsampler) I wrote two trivial test programs usin MIDI over Jack. The first will output a note on or off every 10 ms. The second just receives midi a prints the time (number of frames) since the last event for each one received. When connected directly via Jack the result is a boring series of '480', one event each 10 ms. When connected via a loopback on a HW interface I expected the worst case to be events quantised to Jack period (256 frames). Actually it's 10 times worse - events are bunched into groups, one for every 10 periods. That 53 ms of jitter or if you are optimistic, +/- 26 ms. The interface used is PCI based, no USB problems. What is going one here ? Ciao, -- FA O tu, che porte, correndo si ? E guerra e morte ! _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
