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While playing around with mididings and a script that gets midi information from Robin Gareus' jack_midi_clock I noticed a little flaw with Qtractor as a JACK transport master:
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Start Qtractor
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Load a song, playhead is at 1.1.000 after loading in this example
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play a few bars
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stop playback
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End Qtractor
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Start Qtractor again
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Load the same song, playhead is at 1.1.000 after loading
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play (song starts at 1.1.000 as it should)
Now transport position as displayed in Qjackctl resumes at the old position and doesn't get reset to 1.1.000 -
stop
Now transport position is set to the correct position. From this point on everything works as expected.
It looks as if at first play after loading the transport position is not correctly synced to the playhead position.
re. Incorrect initial JACK transport song position...
check if there isn't any other application playing JACK timebase master around (allegedly not jack_midi_clock)
there can only be one (timebase master) at any one time, otherwise the symptoms you report may arise randomly.
seeya
ps. I assume you're into genuine jackd, not pipewire-jack.
checked, genuine jack2
Killing jack_midi_clock doesn't change anything.
Although the song starts at 1.1.000 its position on Qjackctl is displayed from the old position 2.3.102 on.
When repositioning the playhead after loading and before playing then the correct position is sent (not done in the video).
Only when playing immediately after loading then the initial position is not or not correctly sent.
strange system of mine
I tested the same on another machine, where the playhead doesn't jump to 1.1.000 after loading a song file.
Then the problem I described doesn't manifest.
I have to find out first why on one system the playhead jumps to 1.1.000 after loading a song and on another system it doesn't.
it's an old session
It's not depending on the system but on an old session that I am maintaining through several Qtractor updates.
I'll live with it.
re. re. Incorrect initial JACK transport song position.examined
I found the reason.
If the session is saved with "Transport Mode: Full" then Qtractor reads the song position from jackd and positions the playhead correctly to that position.
But if the session is saved with "Transport Mode: Master" then Qtractor positions the playhead on 1.1.000 but doesn't send a new position. When playback is started then QjackCtl shows that the old position is counted up, what's wrong. When playback is stopped then the correct song position is sent to jack. From then on everything works as expected.
So I'd say that there's a bug in Qtractor. WIth "Transport Mode: Master" Qtractor should send the position 1.1.000 after loading a session because the playhead is positioned there.
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