Can Ardour (3.x) synced to MIDI clock control the jack transport?

Before I put in another feature request, I just want to check if the above is possible… “Can Ardour synced to MIDI clock control the jack transport?”

I haven’t been able to get it to happen, but I might be missing something.


That makes perfect sense.
I’m only really looking for MIDI clock and SPP to control the song position, but it would be nice if this could trigger other jack apps that don’t have MIDI clock sync implemented (or working correctly). This problem will be solved by the completion of MIDI in Ardour… which is presently coming along nicely…

Not really looking for Varispeed. I would only be happy for MIDI to get faster or slower, but audio in my work needs to be constant… If I want it to slow down or speed up (more to the point have the appearance of)… I will use plugins…



I don’t believe so - interaction with JACK transport constitutes being a slave to JACK transport (because JACK transport has no “real” master - any client can control it). Since using MIDI clock implies being in different slave mode, it would require that Ardour could be a slave to two things at the same time.

Moreover, MIDI Clock is not guaranteed to run at normal sample rates, and JACK transport does not permit any speeds other than zero or one (to avoid placing onerous requirements on every JACK transport client). Thus, even if Ardour was to somehow arrange for this, JACK transport could not be used because of this mismatch.

Everyone who thinks that JACK transport should support varispeed should first convince the authors of the many (smaller) JACK clients that pay attention to transport control but would be very unwilling to be required to support varispeed in their code. When that conversation stalls out, then go talk to users who don’t understand why adding client Foo to a JACK setup suddenly stopped varispeed from working (this is a reference to the idea that you allow clients to opt-in for varispeed control, and then disallow it if any clients say they cannot support it).

You might want to look at QJackMMC / jackctlmmc which can control jack’s transport using midi machine control. If you set Ardour to slave to Jack you can control it and any other programs that support Jack transport simultaneously. I use it to drive hydrogen rosegarden and ardour with my HDR, and it keeps them in sync. At least as far as I can hear anyway.