nb_fluid new

nb_fluid

An nb voice mod for norns that plays FluidSynth on norns. It loads any SoundFont (.sf2 / .sf3); with a General MIDI soundfont you get the full GM instrument set and drum kits.

Two ways in, both driving one shared FluidSynth instance:

• nb voices fluid 1 … fluid N: each is one MIDI channel. Pick a program by its GM name, or switch a voice to drums and choose a drum kit.
• a virtual MIDI device called fluidsynth: a 16-channel General MIDI synth for any script with MIDI out, e.g. a MIDI file player. The song picks its own instruments with program changes, and drums are on channel 10.

Requirements

• norns with the nb library (used by the script, not installed separately)
• fluidsynth built with JACK support, and a system service that runs it. The mod installs both itself, see below.

Install

From maiden's REPL:

;install https://github.com/vehka/nb_fluid

or with modhousekeeper, which lists it under "Nota Bene (nb)". Then enable it in SYSTEM > MODS, and restart norns.

The first time a script selects a fluid voice (or sends to the fluidsynth MIDI device), the mod opens an install screen listing what is missing, e.g. "install 2 items". One K3 installs all of them, K2 cancels; E2 shows why each item is needed. When it is done, the screen lists each item as installed, skipped or failed, and K3 closes it. You can also open it from SYSTEM > MODS > NB_FLUID > setup. It installs:

• FluidSynth: apt install --no-install-recommends fluidsynth. Without recommends, so it skips qsynth, a Qt GUI that is of no use on norns. The package brings in a small GM soundfont (TimGM6mb), so it plays right away.
• fluidsynth user service off: the package enables a fluidsynth systemd user service for all users. It would never run on norns, but it is disabled (systemctl --global disable fluidsynth.service) so it can't start a second fluidsynth next to the mod's own.
• nb-fluid service: /etc/systemd/system/nb-fluid.service, which runs fluidsynth for the mod (see How it works). It never starts at boot, only when the mod needs it.
• default soundfont: a link to the system GM soundfont in the soundfont folder.

Anything already in place is left out of the list. The default soundfont is optional: if no system soundfont is found it is skipped, and the rest still installs. Installing uses sudo, which norns has without a password. The install screen comes from norns-deps.

Uninstall

SYSTEM > MODS > NB_FLUID > uninstall, K3, then K3 again to confirm. A screen lists what the mod installed ("remove 2 items"); K3 removes all of it, and the screen ends with what was removed. The mod then deletes itself and turns itself off in SYSTEM > MODS. Restart norns afterwards.

Only what the mod installed itself is removed: if fluidsynth was installed before nb_fluid, it stays. Soundfonts you added to the soundfont folder stay too.

modhousekeeper's Remove does the same (it runs the mod's lib/uninstall.lua before deleting it). Deleting the mod any other way (maiden, rm) leaves the service and packages behind; the service then refuses to start, since the mod's files are gone.

Soundfonts

Put soundfonts in the mod's own folder:

~/dust/data/nb_fluid/soundfonts/

The folder is created when the mod loads. The install links the system's default GM soundfont into it as default-GM.sf2. On norns that is the TimGM6mb soundfont that came with fluidsynth: only ~6 MB, and it sounds thin.

Better-sounding GM choices:

• FluidR3_GM.sf2: FluidSynth's usual default (~140 MB). On Debian it is in the fluid-soundfont-gm package.
• GeneralUser GS: much smaller (~30 MB), a good fit for norns.

Samples load on demand (synth.dynamic-sample-loading), so memory use follows the programs you actually select.

Choosing a soundfont

The soundfont can be changed while a script plays, to audition soundfonts: in PARAMS > fluid synth > soundfont (shown while a script uses a fluid voice), or in the mod menu. The new soundfont is loaded into the running FluidSynth, every voice switches to the same program in it, and the old one is unloaded. Notes keep playing on the old soundfont until the new one has loaded, which takes a moment for big soundfonts.

The choice is global, like the mod menu's, and not saved in psets.

Mod menu

SYSTEM > MODS > NB_FLUID, E2 selects, E3 changes:

• soundfont: which file to load, applied immediately
• voices: number of fluid N voices, 1-16 (applies on the next script load)
• gain: FluidSynth master gain, applied immediately (also in PARAMS)
• setup: ok, or how many dependencies are missing; K3 opens the install screen
• uninstall: K3, then K3 again to confirm, see Uninstall

MIDI device

In SYSTEM > DEVICES > MIDI, assign fluidsynth to a port. norns remembers the assignment like it would for a hardware synth. Then point a script's MIDI output at that port. Handled messages:

• note on/off
• program change (with CC 0 bank select; CC 32 is ignored)
• all CCs (volume, pan, expression, sustain, reverb/chorus sends, all-notes-off, …)
• pitch bend
• GM / GS / XG reset SysEx

Aftertouch is ignored.

MIDI channel N and nb voice fluid N are the same FluidSynth channel. An nb voice only takes over its channel while a script is using it. So for a multi-channel song, send it through the MIDI device rather than an nb voice.

Voice params

Once a script selects a fluid N voice, its param group shows up:

param	what it does
kind	melodic, or drums (bank 128)
program	GM program (melodic)
bank	bank select for non-GM variations (melodic)
kit	drum kit: Standard, Room, Power, Electronic, TR-808, Jazz, Brush, Orchestra, SFX
volume	CC 7
pan	CC 10
reverb	CC 91: FluidSynth's own reverb send
chorus	CC 93: FluidSynth's own chorus send
bend range	pitch bend range in semitones

nb features:

• pitch bend is supported; it bends the whole channel
• modulate sends the mod wheel (CC 1), which is vibrato in most GM fonts

The program and kit lists assume a GM soundfont: program N is preset N-1 in bank 0, and the kits are the GS drum kits in bank 128. With a non-GM soundfont the names don't match what plays, so choose presets by bank and program number instead. A number with no preset behind it doesn't go silent: an nb voice keeps playing its previous preset, and a MIDI program change falls back to bank 0 (the same program, or else the first preset). Either way the log says so. The exception is MIDI channel 10, the drum channel: it only plays bank 128, so it is silent with a soundfont that has no drum kits. Kits other than Standard also need a soundfont that has them. FluidR3_GM and GeneralUser GS both do.

How it works

FluidSynth runs as the system service nb-fluid.service. The mod starts it (sudo systemctl restart nb-fluid) the first time a fluid voice is selected or the MIDI device gets a message, with the soundfont and gain from ~/dust/data/nb_fluid/service.env, which the mod writes first. It drives FluidSynth through its command shell (noteon, select, cc, ...), written to a named pipe, /tmp/nb_fluid.fifo. A service rather than a child process of norns, because the norns 3 beta can't write to a child process (io.popen in write mode).

FluidSynth's JACK outputs are connected to crone's engine inputs (the same inputs SuperCollider uses). That means the ENGINE level, the norns reverb, and tape recording all apply, as for any engine. FluidSynth keeps running across script changes, and stops when norns goes to sleep.

FluidSynth's output goes to /tmp/nb_fluid.log. Look there if nothing plays, and at systemctl status nb-fluid if it doesn't start.

If the mod menu's setup says reboot needed, JACK's files in /dev/shm are gone, so fluidsynth can't connect to JACK. On norns before the fix in monome/norns#1925, logging out of the last ssh session removes them. A reboot brings them back; to stop it happening, add /etc/systemd/logind.conf.d/10-norns-removeipc.conf with [Login] and RemoveIPC=no.

License

MIT