Qtractor as jack slave doesn't change bpm counter when the transport master does

[mxmilkiib]

Tested with seq64. The rate of play in Qtractor changes, but not the bpm number.

[mxmilkiib]

Also, the BBT is thrown off. With tempos manually aligned, the BBT on seq64 matches that given by Qtractor.

[rncbc]

Great finding. Also other classic JACK-timebase master applications (eg. hydrogen) seems to fail to pass this tempo+BBT info to JACK-transport...

If you happen to be using QjackCtl please try your application (eligible to be a JACK-timebase master) and check if the BBT transport information is updated accordingly when transport is rolling. I get that only Qtractor happens to make that right. I feel as puzzled as you :(

If your application don't get timebase (BBT) information into JACK-transport, then there's no way Qtractor can ever read it, even though is set on strictly slave mode (and released from being timebase master).

Maybe you can help on investigating this "blackout"?
Cheers

[rncbc]

any news on this subject, please?

let me give you some insider hints:

1. a jack-transport client may start, stop and (re)locate transport state and position anytime;
2. being a jack-timebase master is something else: no matter if an (yours) application is a jack-transport or not, you must set both a timebase and a process callback, even though the later does nothing or is just a stub eg. => { return 0; }.

number 2) is indeed paramount, otherwise tempo/BBT information won't spread much beyond an (yours) application realm.
hth.
cheers

ps. maybe you should pass this information to seq64 devs, if you're not one of them ;)