Running FluidSynth on a Raspberry Pi 4

Follow this if you want to use components like these:

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So that input from a USB MIDI keyboard is output to the headphone jack:

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Installation guide

Follow https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi up to step 4.
Once you’ve SSHed to the Pi change the hostname from the default:
```
sudo hostnamectl set-hostname fluidsynth.dhpiggott.net
```
Log out and in again for the change to take effect.

Alternatively edit system-boot/user-data before first boot, appending an fqdn directive:
```
fqdn: fluidsynth.dhpiggott.net
```
Optionally enable Byobu on login and customise the notifications:
```
byobu-enable
byobu-config
```
Log out and in again for the change to take effect.
Install FluidSynth:
```
sudo apt install fluidsynth
```
Write this to /etc/security/limits.d/audio.conf:
```
@audio   -  rtprio      90
```
If you skip this step, FluidSynth will run but it will issue this warning:
```
warning: Failed to set thread to high priority
```
Log out and in again for the change to take effect.

Write this to ~/.config/systemd/user/fluidsynth.service:

[Unit]
Description=FluidSynth Daemon

[Service]
ExecStart=/usr/bin/fluidsynth --server --no-shell -o midi.autoconnect=1 -o midi.realtime-prio=90 --audio-driver=alsa --sample-rate=96000 --audio-bufcount=2 --audio-bufsize=960 -o audio.alsa.device=hw:0 -o audio.realtime-prio=90 -o synth.cpu-cores=4 --gain=10 /usr/share/sounds/sf2/FluidR3_GM.sf2

[Install]
WantedBy=default.target

Enable the service:
```
systemctl --user enable fluidsynth
```
Tell systemd to start user services before users login and to keep them running after they logout:
```
loginctl enable-linger ubuntu
```

Check the service status using systemctl --user status fluidsynth.service:

ubuntu@fluidsynth:~$ systemctl --user status fluidsynth.service
● fluidsynth.service - FluidSynth Daemon
     Loaded: loaded (/home/ubuntu/.config/systemd/user/fluidsynth.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2021-03-19 18:21:33 UTC; 3min 29s ago
   Main PID: 21473 (fluidsynth)
     CGroup: /user.slice/user-1000.slice/user@1000.service/fluidsynth.service
             └─21473 /usr/bin/fluidsynth --server --no-shell -o midi.autoconnect 1 -o midi.realtime-prio 90 --audio-driver=alsa --sample-rate=96000 --audio-bufcount=2 --audio-bufsize=960 -o audio.alsa.device hw>

Mar 19 18:21:33 fluidsynth.dhpiggott.net systemd[1733]: Started FluidSynth Daemon.
Mar 19 18:21:34 fluidsynth.dhpiggott.net fluidsynth[21473]: fluidsynth: Connection of Midi Through Port-0 succeeded
Mar 19 18:21:34 fluidsynth.dhpiggott.net fluidsynth[21473]: fluidsynth: Connection of Oxygen 61 MIDI 1 succeeded

Invoke systemctl --user start fluidsynth.service if it’s not already running.