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Controllers Mackie protocol - MCU

Qtracktor 0.9.30 on MXlinux 21.3

Hi there Rui ( and other interrested MCU-protocol surfaces users on Linux ),

First I want to say THANK YOU!! for this Qtractor, this application gives so much joy !

Being a 50+ year old person grown up with those analog consoles with touchable faders, I cant say goodbey to my motorized faders ( my beloved MCU unit ).
Did spent some days doing research Qtractor / Mackie control pro (MCU) posibilities.
Although I did these tests with a original Mackie MCU, there are a lot of controllers which support this mackie-protocol.
I did use the mackie control pro 'standard mode' ( did not boot up in HUI or Logic ctrl mode : holding SEL 1 +2 while powering on the MCU )
Knowing time is limited I hope to present you this information, summed as best as possible, maybe you as a gifted programmer can take a look at these issues.... ( and maybe add some features to Qtractors Controllers window ).
Want to share my experience to others ;

* MCU FADER controlling Qtractors TRACK GAIN :
Fader [ track1 : type=pitchbend, ch=1, parameter=empty, track=0, command=track gain, flags=feedack ] :
- when TOUCHING and moving mcu fader, qtracktor channel fader jumps and moves, although qtractors channelfader is about -7.8dB off ( mcu fader value @ Unity = Qtractor fader= -7.8dB ).
- moving qtractors fader with the mouse, moves the motorized mcu fader ( but again with the -7.8dB off ).
- If you move the mcu fader by finger, AFTER moving qtractors fader with the mouse ;
the qtractors fader follows the mcu fader BUT after releasing your finger from the mcu fader, the mcu fader jumps/returns to the value before moving touching the mcu fader.

When assigning a mcu fader to a plugin parameter ( plugin properties > select parameter > midi controller ) , the plugin parameters acts as predicted when parameter logarithmic is on.
From the properties window also feedack is working. moving mcu fader up/down ; but from the plugins own gui when moving the dail or slider with the mouse there is no feedback on the MCU.
This concept of having next to the plugins' own gui a 2nd plugin properties window for midi controller linking is magnificent.

* MCU solo, mute & rec BUTTON controlling Qtractors TRACK SOLO / MUTE / RECORD :
Solo [ track 1 : type=Note On, ch=1, parameter=8 -G#/Ab-1, track=0, command=track solo, Flags=delta, Feedback ] :
Pressing button on mcu correctly toggles solo qtractor track, but solo led doens't receive any feedack from qtractor ( if led on mcu is lit it stays on, if led is off it stays off ).
When clicking mouse in qtractor on solo, the mcu solo led functions correctly, solo-led goes on and off following on/off status.

For Mute & Rec exactly same behaviour as for solo.

* MCU VPOTS controlling Qtractors TRACK PANNING :
On MCU there are 8 vpots with control change controller 16 for vpot 1, until control change controller 23 for vpot 8. Values for all like described here under.
vpot 1 [ track 1 : type=controller, ch=*, parameter=16 - gen purp slider1, track=0, command=track panning. flags=delta, feedback ]
Rotary 1 outputs control change controller 16 value from 1,4,8,12,15 according to rotationspeed, when rotation up ( clock wise ) or value 65,68,72,76,79 ( CCW ).
Rotating the vpot works on panning, but behaviour is inverted : rotating vpot cw moves trackpanning to the left, while rotating vpot ccw moves qtractors trackpanning to the right.
Although feedback is flagged in qtractor, the vpot led stays at 12 o'clock, leds surrounding the vpots are not moving to the left or right.

When using a vpot to control a plugin parameter ( plugin properties > select parameter > midi controller ) the result is a parameter jumping between min & max while rotating the vpot.
This workflow is not useable and there is also no visual feedack on the mcu rotary ledring.

* MCU TRANSPORT & scrub/jogwheel :
In Qtractors help > shortcuts, did midi controller linking :
mcu play button : transport/play > midi ctrl Type=note on, parameter=94 - A#/Bb6 ( hook & feedback =on ).
mcu stop button : transport/stop > midi ctrl Type=note on, parameter=93 - A6 ( hook, latch & feedback = on ).

Qtractor doesn't feedack led status to MCU when start / stop via computer keyboard shortcut is pressed.
MCU leds above the transport play and stop buttons lit up, but the mcu stop button pres doesn't switch off mcu play button led, and a press on mcu play button doesn't switch off the stop buttons led,
just like qtractor isn't refreshing the feedback commands to the leds when it receives commands from the mcu.

Transport/Rewind & Transport/Fast forward :
After the keyboard shortcut is pressed the timeline keeps scrolling back ( until beginning song ) or forward till the end.
Would be nice if the timeline scrolls back or forward only WHILE the key is pressed ( and stops as soon as you release the key ).

MCU Jogwheel sends controller 60 for both rotating CW as CCW, cw = controller60 with value 1 while ccw =controller60 with value 65.
In Qtractor it's not possible to add this extra value 1 or 65 to the controller 60.

* DISPLAY large mcu display, red colored assignment and smpte/beats display :
With Qtractor 0.9.30, there is none feedback onto these displays.
Would be nice if qtractors api could send track names, panpot, selected channel ( in assignment leds ) and frames/time/BBT to mcu smpte/beat display.

Rui, If I can help you or someone else with information or mcu testing on qtractor linux, just post a reply !!
Happy to help or share some knowledge !

PS : For analyzing what midi data is spit out by the MCU or other midi controller :
Go to the linux terminal & type :
aseqdump -l ( this list all ports, over here see the port where your controller is connected, when port is 24 for example then type : )
aseqdump -p24:0 ( and press any button, move any fader or rotary and see the corresponding midi output in the terminal, which you use inside Qtractors controllers setup or for midi controller to parameter linking ).

Kind Reagrds, Luc.

PDF icon Mackie Control MIDI Map.pdf226.19 KB
rncbc's picture

hi, many thanks for thorough explanation and efforts.

I don't really have the time to check on every detail of the MCU, so sorry; I don't own any MCU equipment and, sorry again, I don't plan to have one ever so soon.

in qtractor model and in general, the "feedback" flag is about the exact and very same MIDI controller message in either direction (MCU -> qtractor and qtractor -> MCU); if the MCU protocol specifies anything different (or even additional) on either end (knob, slider, led, etc.) then it probably won't work or perhaps, only partially;

of course you can simply verify all that by tapping on the MIDI traffic under the hood, with the help of aseqdump as you already know; please confirm or debug whether it's all according to spec, for the cases it's not working right or at all, in either direction.

also, about the jog-wheel and other transport controls: at this time,probably they will only work best *iif* the MCU is configured to MMC mode--dunno if that's even possible; any other option requires development of new driver code, on the qtractor side and that, I'm afraid, is not going to happen on my own, or so soon (see above).

I can, of course help in debugging and possibly fix the generic code-base that is currently in place; anything further than that is going to need some additional (wo)man-power (and time:))

cheers && many thanks anyway

Best Rui,

Thanks for the quick reply and explanation, although hoping for another answer I appreciate this clarity !
It's a shame I can't convince you to purchase such a nice piece of gear, would be looking freaky awesome next to the display with Qtractor on it :-)
Since I'm an end user myself, I can report back any questions or tests about MCU <> Qtractor but I don't have the necessary programming skills to make this happen.

Would be very interested if someone reading this thread in the future with the knowhow and time to make something like this to happen, could post a reply over here.
Mackie MCU in standard mode doesn't send MMC messages ( it's only sending pitchwheel, controller and note on/off data ).

Also interested to hear from other Qtractor users if they use a hardware controller, and with what gear they have a good positive experience !!

Thanx again for Qtractor, Luc.

rncbc's picture

re. qtractor's channel fader is about -7.8dB off...

this might have been fixed today in qtractor >=, but again I don't have a way to test/verify this the MCU side...

please use the repos if you cannot build it on your own, thanks


my keyboard workstation Yamaha MODX acts as a Mackie Control Unit, but uses no feedback. I teached qtractor some controller / transport buttons for easy recording and it works for years now. There is a big endless wheel which does not work correctly, it sends two values alternating but this is not important to me. Thanks for the PDF and the the aseqdump commands.


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