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Qsynth 0.3.6 - Slip Release

Season greetings! It's spring-cleaning time once again. Dust has severely piled up and brand old mite is already lurking around. That's the bad news. Good news are there are plans for this FluidSynth gooey front-end, you know it's about Qsynth. Alas, plans are follow today's slip release though.

Finally, you may say. Not that there's any big (not even small) new features being slung out today. In fact, there's just a lousy couple of the same old crap. Never mind. Big plans are all about getting some channel controllers--also known as generators--into the picture. Yes, finally. It means amplitude, filter envelope generators, LFO modulators, knobs and sliders gore fest and what not. I hear you thinking that's all what a synth is about. And you're damn right. Dropping an initial, synth has been in the name all this time hasn't it? Right, it has been a pretty old plan, ever since early dawn. Well, it still is... a plan.

As always, I won't make any promises, which would be a terrible thing to do, specially from one who keeps calling himself the über-procrastinator. Yeah, I'm sure you know me from previous auto-proclamations. Back to subject at hand, there it is.

Qsynth 0.3.6 slipped away from the dust!

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Qsynth is a FluidSynth GUI front-end application written in C++ around the Qt4 toolkit using Qt Designer. FluidSynth is an excellent command line software synthesizer based on the Soundfont specification.


Project page:



  • Main window layout fixing with regard to its user preferred size and recall when system-tray icon is not enabled.
  • Channels list preset items now activated on double-click.
  • Desktop environment session shutdown (eg. logout) is now tapped for graceful application exit, even though the main window is active (visible) and minimizing to system tray is enabled. Both were causing first shutdown/logout attempt to abort. Not anymore, hopefully ;).
  • libX11 is now being added explicitly to the build link phase, as seen necessary on some bleeding-edge distros eg. Fedora 13, Debian 6.
  • General standard dialog buttons layout is now in place.
  • CMake build system. It was silently available in 0.3.5, but now it is officially unveiled.
  • Fixed a couple of dangling pointers.
  • Mac OSX: Enabled the MIDI name Id option for CoreMIDI driver ports, added the icon to the app bundle.

Weblog (upstream support, yours truly):


Qsynth is free, open-source software, distributed under the terms of the GNU General Public License (GPL) version 2 or later.

Cheers && Enjoy.


this is new and useful and i'm really looking into this.


I made an upgrade from Qsynth 0.3.5 to Qsynth 0.3.6 in openSUSE 11.3
Stupid, I think now, because now it does not work anymore.
When I start qsynth in a terminal I see:
qsynth: symbol lookup error: qsynth: undefined symbol: _ZN9QListData11detach_growEPii
What can I do to solve the problem?

Greetings, Wim

rncbc's picture

it looks like theres a libqt4 version mismatch somewhere; where did you get the qsynth 0.3.6 package? or did you compiled it all from source?



I tried two versions:
- 0.6.1svn378-1.1-x86_64 van openSUSE_Factory en leverancier obs://
- qsynth-0.3.6-2.rncbc.suse114.x86_64.rpm from this site
They had both the same problem.
My libqt4 version is 4.6.3-2.1.1-x86_64 van leverancier openSUSE
(sorry for mixing English and Dutch)

Now I installed 0.3.5-2.rnbc.suse112-x86_64 from Sourceforge and on my big computer (Tyan Tiger S2875 with dual Opteron 254) everything is allright,
but on my laptop (HP 6730s), where I want to make the same installation, Qsynth works but the LSB bank and the MSB bank are exchanged.

Well, I am confused - I hope that you understand what is going on..

Greetings, Wim

rncbc's picture

well, the packages in (my) obs home project (obs:// are for openSUSE 11.4 and up, so you had a libqt4 version mismatch for sure (11.4 and factory repositories are with libqt4 >= 4.7.1).

i've just added the openSUSE 11.3 repo to the open build service (obs) so you probably will get nice packages soon under home:rncbc/openSUSE_11.3.


Hi, thanks for your help! ?
Object not found - Error 404..

How can I add the repository?
And the exchanged LSB and MSB banks on my laptop, can you explain that?

Greetings, Wim

Hi, thanks again :-)

Sorry for my lack of patience while you were working so hard for me.
Now I have added the repository and qsynth works on both computers.

Concerning the bank-exchange, I found the cause:

On my big computer I have:
fluidsynth 1.1.1-1.11-x86_64 van leverancier openSUSE
libfluidsynth1 1.1.1-1.11-x86_64 van leverancier openSUSE
jack 1.9.5-2.8-x86_64 van leverancier openSUSE
libjack0 1.9.5-2.8-x86_64 van leverancier openSUSE
qjackctl van leverancier obs://
This works correct.

On my laptop I had:
fluidsynth 1.1.3-2.pm27.5-x86_64 van leverancier
libfluidsynth1 1.1.3-2.pm27.5-x86_64 van leverancier
jack 1.9.7-32.2-x86_64 van leverancier obs://
libjack0 1.9.7-32.2-x86_64 van leverancier obs://
qjackctl 0.3.7-18.13-x86_64 van leverancier obs://
This gave the exchanged LSB an MSB banks, so I made it just like the big computer and now it works correct.
I think it was a fluidsynth problem, maybe a jack problem - don't know if you like to find it out :-)

Greetings, Wim

I have problems with qsynth-0.3.6 on both Mandriva-2010.2 and Mageia-1.

In both cases it starts fine THE FIRST TIME if I do

qsynth -a jack -r 44100 &

(I use JACK and the default is ALSA, so if I don't do that it just waits indefinitely, since JACK takes over the ALSA device).

BUT, after I do any kind of configuration (e.g. specify the soundfont), qsynth crashes upon the restart with the following message (address might vary):

*** glibc detected *** qsynth: corrupted double-linked list: 0x088ad550 ***

Here is another one:

** glibc detected *** qsynth: double free or corruption (fasttop): 0x09a72808 ***
======= Backtrace: =========
======= Memory map: ========
08048000-080be000 r-xp 00000000 08:06 394526 /usr/bin/qsynth
080be000-080bf000 r--p 00075000 08:06 394526 /usr/bin/qsynth
080bf000-080c0000 rw-p 00076000 08:06 394526 /usr/bin/qsynth
099f2000-0be4f000 rw-p 00000000 00:00 0 [heap]
9fe42000-9fe43000 rw-s 00000000 00:10 63971 /dev/shm/jack-500-5 (deleted)
9fe43000-a4cab000 rw-s 00000000 00:10 60320 /dev/shm/jack-500-0
a4cab000-ada00000 rw-p 00000000 00:00 0
ada00000-ada21000 rw-p 00000000 00:00 0
ada21000-adb00000 ---p 00000000 00:00 0
adb27000-adb28000 ---p 00000000 00:00 0
adb28000-ae328000 rw-p 00000000 00:00 0
b1fe2000-b2158000 rw-p 00000000 00:00 0
b2158000-b2159000 ---p 00000000 00:00 0
b2159000-b21d9000 rw-p 00000000 00:00 0
b21da000-b21ec000 rw-s 00000000 00:10 47054 /dev/shm/jack-shm-registry
b21f2000-b21f3000 ---p 00000000 00:00 0
b21f3000-b2273000 rw-p 00000000 00:00 0
b2273000-b2274000 ---p 00000000 00:00 0
b2274000-b22f4000 rw-p 00000000 00:00 0
b22f4000-b2329000 r--s 00000000 08:07 391713 /var/db/nscd/group
b2330000-b2365000 r--s 00000000 08:07 391712 /var/db/nscd/passwd
b2365000-b2369000 r-xp 00000000 08:06 137578 /usr/lib/kde4/plugins/imageformats/
b2369000-b236a000 r--p 00003000 08:06 137578 /usr/lib/kde4/plugins/imageformats/
b236a000-b236b000 rw-p 00004000 08:06 137578 /usr/lib/kde4/plugins/imageformats/
b236b000-b237b000 r-xp 00000000 08:06 137577 /usr/lib/kde4/plugins/imageformats/
b237b000-b237c000 r--p 0000f000 08:06 137577 /usr/lib/kde4/plugins/imageformats/
b237c000-b237d000 rw-p 00010000 08:06 137577 /usr/lib/kde4/plugins/imageformats/
b237d000-b2381000 rw-p 00000000 00:00 0
b2381000-b238a000 r-xp 00000000 08:06 137575 /usr/lib/kde4/plugins/imageformats/
b238a000-b238b000 r--p 00008000 08:06 137575 /usr/lib/kde4/plugins/imageformats/
b238b000-b238c000 rw-p 00009000 08:06 137575 /usr/lib/kde4/plugins/imageformats/
b238c000-b23d7000 r-xp 00000000 08:06 134550 /usr/lib/
b23d7000-b23d8000 r--p 0004a000 08:06 134550 /usr/lib/
b23d8000-b23db000 rw-p 0004b000 08:06 134550 /usr/lib/
b23db000-b23e1000 rw-p 00000000 00:00 0
b23e1000-b2423000 r-xp 00000000 08:06 134807 /usr/lib/
b2423000-b2424000 r--p 00041000 08:06 134807 /usr/lib/
b2424000-b2425000 rw-p 00042000 08:06 134807 /usr/lib/
b2425000-b243b000 r-xp 00000000 08:06 134809 /usr/lib/
b243b000-b243d000 r--p 00015000 08:06 134809 /usr/lib/
b243d000-b243e000 rw-p 00017000 08:06 134809 /usr/lib/
b243e000-b2511000 r-xp 00000000 08:06 134815 /usr/lib/
b2511000-b2513000 r--p 000d2000 08:06 134815 /usr/lib/
b2513000-b2514000 rw-p 000d4000 08:06 134815 /usr/lib/
b2514000-b2515000 rw-p 00000000 00:00 0
b2515000-b251a000 r-xp 00000000 08:06 137576 /usr/lib/kde4/plugins/imageformats/
b251a000-b251b000 r--p 00004000 08:06 137576 /usr/lib/kde4/plugins/imageformats/
b251b000-b251c000 rw-p 00005000 08:06 137576 /usr/lib/kde4/plugins/imageformats/
b251c000-b2521000 r-xp 00000000 08:06 137574 /usr/lib/kde4/plugins/imageformats/
b2521000-b2522000 r--p 00004000 08:06 137574 /usr/lib/kde4/plugins/imageformats/
b2522000-b2523000 rw-p 00005000 08:06 137574 /usr/lib/kde4/plugins/imageformats/
b2523000-b2527000 r-xp 00000000 08:06 137573 /usr/lib/kde4/plugins/imageformats/
b2527000-b2528000 r--p 00003000 08:06 137573 /usr/lib/kde4/plugins/imageformats/
b2528000-b2529000 rw-p 00004000 08:06 137573 /usr/lib/kde4/plugins/imageformats/
b2529000-b2530000 r-xp 00000000 08:06 137571 /usr/lib/kde4/plugins/imageformats/
b2530000-b2531000 r--p 00006000 08:06 137571 /usr/lib/kde4/plugins/imageformats/
b2531000-b2532000 rw-p 00007000 08:06 137571 /usr/lib/kde4/plugins/imageformats/
b2532000-b2594000 r-xp 00000000 08:06 132629 /usr/lib/
b2594000-b2596000 r--p 00062000 08:06 132629 /usr/lib/
b2596000-b2597000 rw-p 00064000 08:06 132629 /usr/lib/
b2598000-b259d000 r-xp 00000000 08:06 137572 /usr/lib/kde4/plugins/imageformats/
b259d000-b259e000 r--p 00004000 08:06 137572 /usr/lib/kde4/plugins/imageformats/
b259e000-b259f000 rw-p 00005000 08:06 137572 /usr/lib/kde4/plugins/imageformats/
b259f000-b25a3000 r-xp 00000000 08:06 137570 /usr/lib/kde4/plugins/imageformats/
b25a3000-b25a4000 r--p 00003000 08:06 137570 /usr/lib/kde4/plugins/imageformats/
b25a4000-b25a5000 rw-p 00004000 08:06 137570 /usr/lib/kde4/plugins/imageformats/
b25a5000-b25ab000 r-xp 00000000 08:06 134811 /usr/lib/
b25ab000-b25ac000 r--p 00005000 08:06 134811 /usr/lib/
b25ac000-b25ad000 rw-p 00006000 08:06 134811 /usr/lib/
b25ad000-b25b2000 r-xp 00000000 08:06 137569 /usr/lib/kde4/plugins/imageformats/
b25b2000-b25b3000 r--p 00004000 08:06 137569 /usr/lib/kde4/plugins/imageformats/
b25b3000-b25b4000 rw-p 00005000 08:06 137569 /usr/lib/kde4/plugins/imageformats/
b25b4000-b25e9000 r-xp 00000000 08:06 132613 /usr/lib/
b25e9000-b25ea000 r--p 00035000 08:06 132613 /usr/lib/
b25ea000-b25eb000 rw-p 00036000 08:06 132613 /usr/lib/
b25eb000-b25ed000 rw-p 00000000 00:00 0
b25ed000-b265a000 r-xp 00000000 08:06 132627 /usr/lib/
b265a000-b265b000 ---p 0006d000 08:06 132627 /usr/lib/
b265b000-b265d000 r--p 0006d000 08:06 132627 /usr/lib/
b265d000-b265e000 rw-p 0006f000 08:06 132627 /usr/lib/
b265f000-b2660000 rw-s 00000000 00:10 60322 /dev/shm/jack-500-1
b2660000-b2661000 rw-s 00000000 00:10 63969 /dev/shm/sem.jack_sem.500_default_qsynth
b2661000-b2669000 r-xp 00000000 08:06 137568 /usr/lib/kde4/plugins/imageformats/

Sometimes it is a segfault.

Looks like a memory corruption to me, but so far I can't pinpoint it.

I used qsynth-0.3.4 on Mandriva-2010.0 without any problems for a lo-o-o-o-ng time, many thanks!


rncbc's picture

have you tried with any soundfont file and does it crash all the time?

backup qsynth configuration file (~/.config/, put it away and start from a brand new one. qsynth defaults to jack on the audio driver and alsa_seq for the midi one. also, 44100 is the default sample-rate, so that you'll have to make sure jackd does start on that precise rate, otherwise you'll have to match it under qsynth/fluidsynth's engine (cf. Setup/Audio/Sample Rate).

please, test with several soundfonts and report which ones are at stake. if the crash problem happens on all situations then that's probably an issue with your distro supplied packages (qt4, fluidsynth, and whatever else) aren't well suited to each other, perhaps... :/


The problem was happening with several SoundFonts (FluidR3, MusicaTheoria) that I used before.
I've already tried to remove the config -- didn't help either.

Downloaded the source tarball from SourceForge, rebuilt and the problem was gone!

This looks like a distro's problem now, but hard to tell where have they screwed up. Amazingly enough it's two (slightly) different distros.

Thanks a lot for the great SW!


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