[LAD] midi beat clock

Ralf Mardorf ralf.mardorf at alice-dsl.net
Mon Feb 22 18:02:10 UTC 2010

Tim E. Real wrote:
> On February 19, 2010 10:17:12 pm Gabriel M. Beddingfield wrote:
>> 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
> Good stuff. Thanks. Had no idea that 100Hz tick was for time-based sync. 
> Meaning we could use it for audio...
> Interesting, MTC full frames are 12Hz (@ 24fps) and quarter frames @ 96Hz.
> (Correct my rusty reviewing).
> But Paul said that it can be 'quite bursty', I assume he meant the 
>  quarter frames - and I think I also read one should not trust the full frame 
>  to occur precisely 'where it should be'. After all, it is a sysex...
> So I Wonder if 'tick' is a more stable, straight forward, and faster option
>  for basic uses vs MTC at 24fps
> Still curious, someone said he had this 'tick', which app sends it?
> Imagine. Midi clock, active sense, tick and/or MTC all on the same line...

There must be a misunderstanding. IIRC Paul said that MIDI clock can 
become an issue.
I was using SMPTE for a long time and it's absolutely usable for every 
sync situation. I guess that MTC is equivalent to SMPTE.

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