Problem "fluidsynth not found" thonny under ubuntu 24.04

Errors
#1

Hello everyone,
I used scamp on my Ubuntu 20.04 laptop and it worked fine.
Now I moved to 24.04 (on the same laptop) and I have a problem with fluidsynth.

Description:

I follow the basic steps given on the home page, that worked perfectly on ubuntu 20.04 : installed scamp, abjad, rtmidi, pynput, lilypond from thonny. And then install fluidsynth from the ubuntu console with apt install command.

But it doesn’t work! Whatever I do, even just play a single piano note, I get the error message. Tried to reinstall, reboot… nothing worked out. I am quite puzzled.

I searched the web and no idea… So if any scampster is coming to help I’ll be very happy

Error printout: (from asking scamp to play a single piano note)

WARNING:root:Fluidsynth could not be loaded; synth output will not be available.


# The full code that resulted in the error:
```python3
from scamp import *
s = Session()
piano = s.new_part("piano")
piano.play_note(70,1,1)

the full error message:
WARNING:root:Fluidsynth could not be loaded; synth output will not be available.
Using preset Piano Merlin for piano
Traceback (most recent call last):
File “”, line 5, in
File “/var/data/python/lib/python3.12/site-packages/scamp/instruments.py”, line 186, in new_part
instrument.add_soundfont_playback(preset=preset, soundfont=soundfont, num_channels=num_channels,
File “/var/data/python/lib/python3.12/site-packages/scamp/instruments.py”, line 1010, in add_soundfont_playback
SoundfontPlaybackImplementation(bank_and_preset=preset, soundfont=soundfont, num_channels=num_channels,
File “/var/data/python/lib/python3.12/site-packages/scamp/playback_implementations.py”, line 328, in init
SoundfontHost(
File “/var/data/python/lib/python3.12/site-packages/scamp/_soundfont_host.py”, line 176, in init
raise ModuleNotFoundError(“FluidSynth not available.”)
ModuleNotFoundError: FluidSynth not available.

#2

What happens if you open a terminal and type fluidsynth? Does it recognize the program?

#3

Hi Marc,
thanks for the quick answer. It does but it seems to have a priority issue… here is the message

FluidSynth runtime version 2.3.4
Copyright (C) 2000-2023 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of Creative Technology Ltd.

fluidsynth: warning: Failed to set thread to high priority
Type ‘help’ for help topics.

fluidsynth: warning: Failed to set thread to high priority

#4

I’m diving into this on the net.
I’ll come back if I have (or not) found a solution

#5

Hi,

bad news… it took some time to make fluidsynth work. Now it does properly, the solution was to install Ubuntu Studio which enables realtime kernel. I tried to make a lowlatency kernel by hand but it did not work.

Anyway fluidsynth works properly from the terminal, but with the same basic script I get now a new error… python (or scamp) does not find fluidsynth. Tried to uninstall fluidsynth and I got the same error message! Is there a conflict with Ubuntu Studio? Should I uninstall it (actually it is just a simple way to install a lot of audio-related packages) and try to have a realtime kernel otherwise (but this seems it is trickier with the ubuntu 24.04).

Here is the error message:

WARNING:root:Fluidsynth could not be loaded; synth output will not be available.
Using preset Piano Merlin for piano
Traceback (most recent call last):
File “”, line 3, in
File “/var/data/python/lib/python3.12/site-packages/scamp/instruments.py”, line 186, in new_part
instrument.add_soundfont_playback(preset=preset, soundfont=soundfont, num_channels=num_channels,
File “/var/data/python/lib/python3.12/site-packages/scamp/instruments.py”, line 1010, in add_soundfont_playback
SoundfontPlaybackImplementation(bank_and_preset=preset, soundfont=soundfont, num_channels=num_channels,
File “/var/data/python/lib/python3.12/site-packages/scamp/playback_implementations.py”, line 328, in init
SoundfontHost(
File “/var/data/python/lib/python3.12/site-packages/scamp/_soundfont_host.py”, line 176, in init
raise ModuleNotFoundError(“FluidSynth not available.”)
ModuleNotFoundError: FluidSynth not available.

#6

Tiny update. I ran a debug (found this on another topic) using this python code:

import logging; logging.getLogger().setLevel(logging.DEBUG)
import scamp

This is what I get:

DEBUG:root:Trying to load copy of pyfluidsynth from within SCAMP package.
DEBUG:root:Trying to load fluidsynth DLL/DYLIB from within SCAMP.
DEBUG:root:No local copy (not on mac or windows).
DEBUG:root:Loading of SCAMP’s copy of fluidsynth DLL/DYLIB failed.
DEBUG:root:Trying to load system copy of fluidsynth DLL/DYLIB.
DEBUG:root:Could not find system copy of fluidsynth DLL/DYLIB.
DEBUG:root:Loading of pyfluidsynth failed.
DEBUG:root:Trying to load system copy of pyfluidsynth.
DEBUG:root:Loading of pyfluidsynth failed again.
WARNING:root:Fluidsynth could not be loaded; synth output will not be available.

#7

Okay, I remember encountering this issue before. It’s a problem with thonny, and specifically with an environment variable called LD_LIBRARY_PATH, which tells python where to look for the fluidsynth library. How did you install thonny? Through the installer? Through pip? I think it might be an issue when you use the installer on linux.

under Run>Configure Interpreter>General, I had this line in my environment variables:

export LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}/home/marc/apps/thonny/lib

But I don’t think it’s needed anymore?

#8

Hi Marc,
it works thank you very much!

I actually uninstalled Thonny and reinstalled it via the script they provide on their website. The first installation I made was through the Ubuntu dashboard (always the worst option ;-)).

The sound works, there is no more error message. But the actual sound is weird like if it was vibrating or like I has a square LFO tuned at a quite high frequency there…

Sorry to bother again. With the recent distros the sound is played by pipewire. I tried to switch back to pulse+jack but the issue was still there. Is there some setting to take care of?
I searched elsewhere but I did not find anything pointing this kind of problem.

#9

Hi Marc,
I fixed it! It was a buffer problem for the soundcard. Moved it to 256 and now your wonderful program works perfectly fine.
I’m eager to play with that.
Thanks for your time and patience

#10

That’s great! Also, remember that you can use new_midi_part or new_osc_part to drive playback from other programs on your computer.

Oh, and in case you’re interested I’m teaching a workshop starting this weekend!

#11

Hi Marc,
sorry for the late reply. The workshop seems very interesting, but it’s a bit tight for my schedule right now. Maybe in the future!
Enjoy!