[ubuntu-studio-users] Need advice/help with Qjackctl and some other related programs it supports

stephen stevecook172001 at yahoo.co.uk
Wed Jun 10 11:59:55 UTC 2015

Hello Folks. Steve Cook here:

I am currently running Ubuntu Studio and need some help with adjusting a 
midi/audio setup that involves the use of QJackCTL, Qsynth, VMPK and 

See below for a diagram of my current setup (please copy and paste the 
link, below, into a browser to view diagram):


All of the above components are connected together using QJackCTL. The 
way they work is: a midi tune is loaded into rosegarden and played. The 
midi signals are first sent to VMPK, which displays which notes are 
being pressed as the tune progresses. However, VMPK also passes these 
midi signals through to Qsynth, Which, in turn, passes them to the 
system speakers. Thus, the tune is heard throuigh the system speakers in 
correct time with the keys that are being depressed in VMPk. Meanwhile, 
I also have my real world external midi keyboard controller attached to 
VMPK via Qjackctl. This allows me to press the keys on my controller and 
have these key depressions appear on VMPK as well as have them also 
passed onto Qsynth and then onto the system speakers. This means I can 
simply follow what I am seeing on VMPK, in terms of input from 
Rosegarden, on my midi controller. If I press the same keys on my midi 
controller as are initially being pumped to VMPK from Rosegarden, the 
midi song will sound in tune. If I do not, then it will sound out of 
tune and I will be able to immediately auditorily (as well as visually) 
recognize that. In short, then, this system allows me to learn a tune by 
seeing and copying instead of having to read music.

I have made a video of the above setup on You-Tube for a fellow user on 
another forum. So, it might help to more easily understand my setup by 
viewing it:

https://www.youtube.com/watch?v=vRpDbe5hQJE (I am running Ubuntu Mate 
over the top of Ubuntu Studio in this video, just in case you were 

Okay, having explained all of the above, I now need to explain what am 
trying to do with it in terms of extending it's functionality. My 
proposed setup is (please copy and paste the link, below, into a browser 
to view diagram):


I know, diagrammatically, how to setup the proposed arrangement, above. 
What I don’t know is how to tell Rosegarden this is where I want the two 
different tracks to go. Tthat is to say, the two different instruments 
in the midi file are represented as two separate tracks in Rosegarden. 
At the moment (with my existing setup), if I send the signal out from 
Rosegarden to a single instance of VMPK, VMPK only picks up the first 
track and ignores all others. I currently get round that by merging all 
tracks in Rosegarden into a single track and then sending that to a 
single instance of VMPK and this works fine. However, what I want to do 
is to keep the tracks separate and send them to two separate VMPK 
keyboards simultaneously, as per my second diagram. Is that possible 
with Rosegarden? I should say, the reason I want to send the two tracks 
out to separate VMPK's is twofold. Firstly, my two real world midi 
controllers are 61 keys each and not full 88 keyboard controllers. Thus, 
some tunes span a sufficient range of keys as to require me to play with 
my left hand on one keyboard and my right hand on the other. That is to 
say, I set my left hand controller to start three octaves lower than the 
right one. Thus, they overlap by two octaves. Between them, though, I 
get a full 88 key span. The second reason I want to send different 
tracks to each of the keyboards is because some of the midi tunes I am 
wanting to learn are for duets between two instruments. And so, my 
proposed setup would allow me to effectively playback the two 
instruments simultaneously from Rosegarden to two instances of VMPK.

Rosegarden appears to allow the sending of the midi signal from each 
track to separate outputs. But I cant get them to work. so I am 
obviously doing something wrong. I should make it clear, finally, that I 
do not have a problem with the external midi controllers themselves in 
that it is perfectly possible for me to connect them both up to two 
instances of VMPK and have /them/ both play with two separate voices at 
the same time (in other words, my second diagram, minus Roasegarden). 
The problem is between Rosegarden and VMPK.

Please help, if you can.

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