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qmidiarp not working in Track/Export Tracks/Audio... (bug?)

I'm using qmidiarp as a LV2 plugin in a song on some tracks and it all works fine when composing and arranging, but when I try to export the song to a wave file with Track/Export Tracks/Audio I can hear the other tracks, but nothing from the tracks using qmidiarp. I think this is a bug, but I am unable to make a ticket in qtractor so I'm reporting it here.

Another observation is that qmidiarp is missing the first note if I start playing from the first beat in the first bar. It is easy to work around by leaving the first bar empty so playback starts before encountering the first note. Perhaps these problems are related?


Up until now I've been using the KXStudio version of Qtractor. So, I just grabbed the git version, installed the libraries needed for configure not to throw up errors, and got it to make (I also needed libqt5x11extras5-dev for make to complete), now I've got a shiny new Qtractor! As a side note, I'm using Ubuntu Studio 16.04 with many repos added.

The audio track export (non-realtime) works with QMidiArp now- but, it seems like the phasing of the QMA program is different, at least that's what I think I'm hearing (as a side note there is another issue I'm having- I can't record the midi output of QMA- I can give more details on what I've tried- Rui, should I start a new thread for that or do a new post in this one?).

To illustrate, here's one of the sections rendered out in realtime-

Versus exported in non-realtime- ).

Here's the QMA pattern-
PAsting it in the forum can cause issue- the angle brackets don't play nice in the html ;-)

And the midi file of the chord progression-

The folder all that is in is a dump of the working directory-

I'm just thrilled to be making progress!

rncbc's picture

... it seems like the phasing of the QMA program is different
what you mean by phasing in this context? is it that generated events are out of phase or delayed, out of time? i guess the ball is now on Frank's side :)

...I can't record the midi output of QMA
that's actually expected: MIDI produced by plugins are not routed anywhere but in through the plugin chain they're in, so you can't record it; but there's a hack you can do: insert a MIDI Aux-Send after qmidiarp and fork its output into some other MIDI output bus and then bounce/record from its output ports--tricky, but doable ;)


Yep, ball on my side received ;) I suspect this is related to the missed first note when timings of incoming and (to be) outgoing notes are exactly equal. We'll discuss that in qmidiarp bug over at sf. Thanks much Rui anyway!

Yes, I tried using the MIDI Send- going by the earlier method of capturing the audio from the synth plugins- being sure to connect things up in the connections dialogue, but no go. I tried every way I could see of hooking things up. Not sure what the "Dedicated MIDI player outputs" are in the Options > MIDI section, but I enabled it and connected it as well, but still nothing recording.

I started using GMIDImonitor to see if I could tap into things- I can see the QMA output, but it's not being recorded. Here's a screenshot-

I have it sent to a new midi track as well as GMIDImonitor- the QMA notes appear in the monitor, but aren't recorded to the track.

The working folder for the project is here-

rncbc's picture

hi all, who's still here :)

after some hair-pulling and ghost-hunting, it finally come to my attention that regular JACK transport/position is NOT being updated when in freewheeling mode.

so that the host time/position information that is fed to LV2 plugins only happens when export starts and ends, passing the same and current play-head position which is not, almost never, the correct one at all.

this has been corrected on git head today (>= so I pledge your patience to test it all over again.

thanks in advance.

Okay, gave it a try, but now I'm not getting any sound from my MIDI tracks- tried starting a new project, new MIDI track, add an instrument (mda piano), import a MIDI file- no playback, adding an audio insert doesn't help, mixdown/export produces a blank audio file. When I uninstall and install the previous version (, load the file I just created, and all is good again.

The new ( version has this error popping up after I add the audio send-
jack_port_get_all_connections called with an incorrect port 0

Here's an example of that process-

With the earlier version (, things were starting to work with the new QMidiArp- Frank did some updates that has improved things.

rncbc's picture

sorry, there's a regression on today's that should fix it!

thanks for the heads-up!

ps. next time you share a qtractor session you can bundle it on one single archive/zip file by just saving as with the ".qtz" suffix ;)
pps. you also should know that audio export does not handle dedicated output ports, right? audio export only applies to regular audio output buses.

Cool, it's back again- thanks :-)

"you can bundle it on one single archive/zip file by just saving as with the ".qtz" suffix"

I figure there was a way to do that- so obvious- d'oh! Thanks for the heads up, will make transferring projects so much more sane!

Not sure what's meant by "dedicated output port"- I only got the error with the version- it's gone now in

Figured out what I was doing wrong- the midi channel is incremented with each new track, I did not notice this, so now I can capture the midi output of QMidiArp, in realtime at least.


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