[Ardour-Users] recognizing external timebase tempo changes?

Studio Channing studiochanning at yahoo.com
Mon Jan 20 15:53:45 PST 2014

On 01/19/2014 02:32 PM, Paul Davis wrote:
> On Sun, Jan 19, 2014 at 4:17 PM, Studio Channing 
> <studiochanning at yahoo.com <mailto:studiochanning at yahoo.com>> wrote:
>     Hi all, is there any way to allow Ardour to recognize tempo
>     changes as produced by a different Jack transport master?
> Ardour will always ignore the tempo information present in the JACK 
> transport system.
> Applications like Ardour require a "tempo map" rather than a 
> simplistic instantaneous value for tempo and meter, unless they are to 
> be limited to pieces that remain at the same tempo + meter throughout. 
> We have never devised an acceptable, portable "tempo map" description 
> that could be shared.
> --p

Thanks for your reply, and for making such great software!

Are you saying that Ardour will always require the tempo information 
ahead of time? Otherwise couldn't a tempo map in theory be constructed 
on the fly from the incoming values?

In practice that's actually what we see when we reverse roles - using 
Ardour as a MIDI sequencer with tempo changes in its session and 
Qtractor as the harddrive recorder: when Ardour as timebase master 
changes the tempo Qtractor shows/uses the new value and also creates its 
own tempo marker at that "spot".

Granted this raises questions - like where that spot is precisely - 
sounds like JACK transport will only update tempo between process 
cycles? Also the question of how incoming tempo changes interact with a 
pre-existing session tempo map - looks like Qtractor just deletes 
existing markers as you roll through them..

In any case, what if we abandon tempo via JACK transport - is it 
possible to have Ardour recognize incoming tempo changes "on the fly" 
via other means? e.g. sending MIDI tempo events FF 51.. ?
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