On Fri, 2012-09-21 at 15:06 -0400, Tim E. Real wrote:
  Midi sync clock output on the other hand, is a bit
weaker at the
 moment.
 It should work, but sync output needs some fixing for accuracy and
 timing,
  best results may be with the ALSA devices instead of Jack midi
 devices. 
Use Jack2 ex 1.9.8 with the alsarawmidi driver, unfortunately missing
for the Ubuntu Studio Precise package, but jack2 is easy to compile and
other distros, e.g. Arch include it.
Example: jackd --sync -Xalsarawmidi -dalsa -r48000 -p256
"alsarawmidi" is the only way on my machine to get hard real-time, aka
zero jitter, at least in the past. At the moment, perhaps regarding to
new kernels or new video drivers, my Linux are broken regarding to audio
productions.