Tempo sync through Jack


Using Ardour 5.5.0 I have discovered and used the “tempo ramps” feature. In standalone Ardour, this works very nice.

Having Hydrogen running, it does not follow the gradual tempo change of the ramp I created.

To be precise: Ardour’s tempo-display (secondary clock) changes as it should, but Jack’s does not (when viewed using qjackctl).

How can I get Jack (and subsequently Hydrogen) to follow along the tempo ramp from Ardour?

Thank you very much,

Frans-WIllem Post

JACK cannot represent tempo ramps in any sensible way.

It sounds as if there may be a bug in setting the JACK tempo information, but even if this bug is fixed, you should not expect JACK to be able to keep multiple applications in sync if Ardour is ramping. JACK’s model of tempo just does not include ramping. If it works, it will only be because the changes are slow enough or small enough for the errors not to matter.

I tried another approach: the klick metronome. Called as klick -T -f /path/to/tempomap, it enables Jack to a sort-of ramping tempo.

Now my Hydrogen is following nicely, but Ardour is not. Ardour’s click just keeps on clicking with the initial tempo.

Is it possible to get Ardour to follow not only Jack’s transport, but also its tempo?

Thank you,

Frans-Willem Post

Ardour will not use tempo information from an external source. Again, there is no standard way to represent tempo ramps in a way that can be shared among applications.