[LAU] MIDI clock & sync

Paul Davis paul at linuxaudiosystems.com
Wed Aug 5 18:27:47 EDT 2009

On Sat, Aug 1, 2009 at 6:34 PM, Julien Claassen<julien at c-lab.de> wrote:
> Paul!
>  OK, I got this. But two questions arise:
> 1. Is MIDI clock realtime? If so, it could still be used for simple
> alignment purposes.

Gabriel took care of that one.

> 2. If MTC measures realtime in hh:mm:ss... then why does it seem so dificult
> to have a program that can translate between it and jack timestamping or LTC
> or whatever it is called? Or am I again mixing it al up? I assume it's
> highly possible.

It is possible and I think there has been mail from Robin or someone
else noting that they have already done it.
LTC is an audio signal, basically a modulated sine wave that encodes
the positional values. Thus  converting between it and MTC is not an
entirely trivial operation. But its also not super-hard (well, hard
enough that it needs somone of Robin's skill level to implement).

>  Another thing: I would/could theoretically use MTC to sync my MIDI-only and
> audio-only apps.

very few "MIDI apps" understand MTC. MTC is really just a
transformation of *VIDEO* timecode into  a special kind of MIDI data
stream. it has little or nothing to do with the musical time that most
MIDI apps are concerned with.

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