FIZZ

FIZZ is a step sequencer for FM TONE, ChoralRoot's FM synth voice, made for the M-VAVE FM-1. It has eight tracks sharing 16 voices, track defaults with per-step overrides, p-locks, a pool of 128 sounds, pages with their own start and end, conditions, chance, ratchets and chords of up to six notes.

Phase 1 (now) runs on the Mac as an FM1VST core. The real FM-1 is its panel through RemoteFM1: the keys, the knobs and the screen are the unit's, and the sound comes from the Mac. Phase 2 will be the FM-1 firmware itself.

Play the preview in the browser (the on-screen FM-1, or your own FM-1 with RemoteFM1), and send feedback from there. The site is site/.
PLAN.md: the design, the controls (§8b) and the build log (§13).
PLAYING.md: how to play it, organised by "how do I ...".

Build and test

The core is plain C99 with no OS calls (simulated time, deterministic). Its tests and the headless screen renders need only a C compiler:

make -C tools test      # the sequencer, the voices, the controller (ASan + UBSan) and bit-exact checks against ChoralRoot
make -C tools frames    # every screen as a PNG in core/tests/out/ (and the idle screen as a GIF, with ffmpeg)
make -C tools audio     # the demo patterns as WAV files

The bit-exact tests read ChoralRoot's tagged source from a checkout next to this one (CR_REPO, default ../ChoralRootFM1).

To build the FM1VST core module, configure an FM1VST checkout with this tree as FIZZ_DIR, building only this core:

cmake -S path/to/FM1VST -B build-fizz -DFM1_ONLY_CORES=fizz -DFIZZ_DIR=$PWD
cmake --build build-fizz --target fizz_core core_smoke core_conformance
ctest --test-dir build-fizz -R 'fizz|common'
make -C tools abi FM1CORE=path/to/build-fizz/cores/fizz.fm1core   # the module driven through the core ABI

License

MPL-2.0 (see LICENSE and LICENSING.md; site/ and the bit-exact tests' oracles stay GPL-3.0-only). Until L1 (2026-10-23) FIZZ was GPL-3.0-only; Felucca's code was rewritten, not relicensed (research/PROVENANCE.md).

Credits

FM TONE, the effects (chorus, delay, reverb) and the output chain: ChoralRoot FM-1 v0.25.1, the owner's (relicensed MPL-2.0 by him); ChoralRoot began as a fork of Felucca (Leo Kuroshita, Hügelton Instruments), whose code FIZZ no longer holds (L1: rewritten clean-room).
Drawn with plutovg (MIT; its FreeType parts FTL, stb MIT OR Unlicense), vendored in third_party/plutovg with FIZZ's changes listed in third_party/README.md.
Type: Inter Tight (SIL Open Font License 1.1).
The sequencer's controls owe a lot to the OMX-27 Form sequencer and to Elektron's machines.