[LAD] midi beat clock

[Gabriel M. Beddingfield]

Hi wolke!

On Sat, 20 Feb 2010, m.wolkstein at gmx.de wrote:

> for more information's read here.
> http://en.wikipedia.org/wiki/MIDI_beat_clock
>
> my question, exist something like this for alas. i am interested to send midi beat clock
> signals from hydrogen to external hardware synthesisers/arpeggiators. and i am explicit
> not interested to sync them to any timecode. because the external machines have to run
> independent and in a randomly order. they only have to sync there beats.

I wrote a program to do this.  It slaves to the JACK 
transport and sends out MIDI clock pulses accordingly.  You 
can check it out here:

     http://www.teuton.org/~gabriel/jack_midi_clock/

I've used this to record with Ardour and a Korg MS2000R. 
The MS2000R is able to sync arpeggiators and LFO's to MIDI 
clock pulses.  It ignores start/stop/continue messages. 
However, jack_midi_clock still implements those.  It does 
/not/ implement MIDI Tick (but it could...).

> and about ticks.
> i fond out that linux audio apps all have other or there own definitions about the quantity of ticks per beat.
> make it sense to find out an accordance about ticks per beat. or is this irrelevant for any syncing. especially i mean here syncing via jack-transport.

As PD said, the MIDI spec requires That MIDI Clock (0xF8) 
pulses be sent out at a rate of 24 clocks per quarter note. 
Meanwhile, a MIDI Tick (0xF9) is sent out at a rate of 1 
tick per 10 ms.  The difference is whether you are syncing 
time or tempo.  Sounds like you want tempo (MIDI Clock 
0xF8).

There's a pretty good MIDI reference here:

     http://www.blitter.com/~russtopia/MIDI/~jglatt/tech/midispec.htm
     http://www.blitter.com/~russtopia/MIDI/~jglatt/

FWIW, using MIDI clock you can effectively sync tempo. 
Synchronizing down-beats is more difficult... since there is 
never a signal that says "this clock pulse marks a beat."

Hope this helps!

-gabriel