#76 klick slave playback issues


qtractor doesn't play nicely when acting as a JACK tranport slave to klick when klick is speeding up or slowing down (aka tempo ramping or accelerando/ritardando).

MIDI tracks seems to fall out of sync with one another in 'Full' transport mode and in slave mode the transport stops playback after playing the first event.


  • Daniel MacDonald

    The MIDI tracks don't really fall out of sync with one another when klick is ramping the tempo and qtractor is in Full transport mode. A more accurate description of the problem is that not all notes get played when the tempo is changing.

  • Rui Nuno Capela

    Rui Nuno Capela - 2013-11-15

    what you're trying to do is not well supported by jack transport or qtractor by any chance.

    tempo (bpm) changes are informational data that get set by a time master jack client, both klick in your case and qtractor when in full transport mode.

    there can only be one jack transport master at any one time. having both klick and qtractor as time masters leads to undefined behavior due to unpredictable race conditions on which one sets the current jack transport tempo or bbt position first.

    and when qtractor set as a slave can hardly catch up with tempo ramps, just because it doesn't do any at all: tempo changes are read as a whole and qtractor will just set it globally or to the nearest existing tempo map node/bar position.

    you can always have interesting or funny rhythmic results though but hardly the ones you'd ever expect, deterministically speaking ;)


  • Rui Nuno Capela

    Rui Nuno Capela - 2013-11-26
    • status: open --> pending
  • Rui Nuno Capela

    Rui Nuno Capela - 2013-12-11
    • status: pending --> closed

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