[fluid-dev] Ubuntu 20.04: Rosegarden - Fluidsynth version mismatch

[Dorien James]

I have a problem with the way that Rosegarden is interacting with Fluidsynth, and I would welcome any help or at least further debugging suggestions.

tldr: Rosegarden appears to be asking, via fluidsynth-dssi, for an obsolete version of Fluidsynth, and failing to load it as a result.

For a few years, I've had a stable Rosegarden environment working happily with Fluidsynth on Ubuntu 16.04:
-    rosegarden 15.12.1
-    fluidSynth 1.1.6
-    fluidSynth-dssi 1.0.0
-    libfluidsynth 1.1.6

I'm now building a new machine under Ubuntu 20.04, and have installed latest versions of everything:

dorien@dorien-M4500:~$ dpkg -l | grep "rosegarden"
ii  rosegarden                                 1:19.12-1build1                     amd64        music editor and MIDI/audio sequencer
dorien@dorien-M4500:~$ dpkg -l | grep "fluid"
ii  fluid-soundfont-gm                         3.1-5.1                             all          Fluid (R3) General MIDI SoundFont (GM)
ii  fluidsynth                                 2.1.1-2                             amd64        Real-time MIDI software synthesizer
ii  fluidsynth-dssi                            1.0.0-7                             amd64        DSSI wrapper for the FluidSynth SoundFont-playing synthesizer
ii  libfluidsynth2:amd64                       2.1.1-2                             amd64        Real-time MIDI software synthesizer (runtime library)
ii  qsynth                                     0.6.1-1build1                       amd64        fluidsynth MIDI sound synthesiser front-end

When I run Rosegarden from terminal, the messages include:

[JackDriver] initialise() - connecting from  " rosegarden:master out L " to " system:playback_1 "
WARNING: DSSIPluginFactory::discoverPlugin: couldn't dlopen /usr/lib/dssi/fluidsynth-dssi.so - libfluidsynth.so.1: cannot open shared object file: No such file or directory
[JackDriver] initialise() - connecting from  " rosegarden:master out R " to " system:playback_2 "

Once in Rosegarden, Fluidsynth doesn't work:
-    it's not listed on the list of Plugins on the Synth plugin window
-    if I load a .rg file including Fluidsynth instruments from my old environment, there's an error window "The following audio plugins could not be loaded: FluidSynth-DSSI"

/usr/lib/dssi/fluidsynth-dssi.so exists in both environments.

However, the directory /usr/lib/x86_64-linux-gnu on my old, working environment contains a file libfluidsynth.so.1 which appears to be a link to libfluidsynth.so.1.5.2
The same directory on my new environment contains libfluidsynth.so.2 linking to libfluidsynth.so.2.3.1

So, as far as I can tell, either Rosegarden or fluidsynth-dssi is expecting to use libfluidsynth.so.1, but this no longer exists. 

Views gratefully received on where the problem might lie and how I might fix it.