[LAU] what's up with midi clock

Gabriel M. Beddingfield gabriel at teuton.org
Sat May 30 15:46:16 EDT 2009


Atte André Jensen wrote:
>> I would also try it _without_ the S.
> 
> Then the tempo works just fine, however the two apps have different 
> downbeats.

Does sooperlooper respond to Song Position Pointer (0xF2) and/or MIDI Continue 
(0xFB)?  You may be able to sync time using these instead of Song Start (0xFA). 
  Song Position Pointer sends a 14-bit song position, followed by a MIDI 
Continue which means ("start playing at that spot on the next clock tick").  The 
14-bit song position is in "MIDI beats" since the beginning of the song.  6 MIDI 
Clocks == 1 MIDI beat.

Also, I noticed that sooperlooper is determining tempo by some manner of rolling 
average calculation.  (Maybe it doesn't, but that's the way it *acts*.)  If so, 
that makes it even harder to get sooperlooper to sync to a downbeat.

> As just outlines in another post, the problem is a bit more complex, as 
> is involves chuck which doesn't sync to anything. Also chuck and 
> sooperlooper are running on two different laptops...

Right now, the laptop 2 has a chuck script that listens for OSC messages and 
feeds sooperlooper a MIDI clock.  Instead, you could write a simple C program 
that listens for OSC messages and is the JACK transport master.  Writing a 
transport master is not very difficult.

Looks like Esben Stein did exactly this recently:

   http://www.nabble.com/JACK-Transport-td23135202.html

Also, perhaps netjack already has this ability.

HTH,
Gabriel




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