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 Linux-audio-dev@email-addr-hidden http://lists.linuxaudio.org/listinfo/linux-audio-devReceived on Thu Mar 25 00:15:03 2010
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