Opus

Mods for the original Teenage Engineering OP-1, firmware 246. By LizardMan.

A hobby project, built in free time and at its own pace. Help is always welcome, and if you'd like to support it, there's Ko-fi.

Opus 2 is out as a beta: not a bigger pack, but a plugin manager for the OP-1. Its small core loads plugins, .opmod files you copy into a mods folder on the OP-1's disk. Add one, remove one, swap them, no reflashing. The starter pack has all of Opus 1's features as plugins, plus dx (a DX7 voice player for your own .syx banks), outatime (a time-travel synth engine), iter (the OP-1's own hidden engine), a trigger guard for worn keys and a Halloween colour theme. The bridge, an alpha, runs op1r's and Hundekraft's synths, effects and sequencers on Opus.

• The core: make the update from your own stock firmware with the patcher at https://opus-op1.pages.dev/patcher/. It runs in your browser and nothing is uploaded.
• The plugins: the starter pack, each plugin on its own and the bridge are in Releases.
• Your own plugins: the plugin kit (GPL-3.0).

Opus 1 (1.0.1) stays on the site as legacy, one pack built and tested together: https://opus-op1.pages.dev/opus1/

Report a bug · Ideas and questions · Releases

Moving in and out

Opus is built so you can try it without risk and leave without losing anything.

• Coming from stock, Opus 1, op1r or Hundekraft: your sounds, presets and tape stay. Opus 1's sounds play with the starter pack in the mods folder. op1r's and Hundekraft's synths, effects and sequencers play with the bridge.
• A plugin removed: a sound that needs it is kept exactly as it is, shows "needs" with the plugin's name, and plays again when the plugin comes back.
• Leaving: the cleaner (Opus's menu, system) makes your data ready for stock or another mod, and keeps a copy of everything it changes. Install Opus again and it all comes back. Going back to Opus 1 needs no cleaner.
• The way back is always there: Opus never changes te-boot, the OP-1's own updater and recovery.

How Opus 2 works

• IDs nobody has to hand out. Every plugin is named by its author and itself, like opus.plate or yourname.delay, so names don't collide and nobody has to keep a list.
• A small description file per plugin: its ID, name, author, version, the core version it needs and what it adds.
• Libraries. A plugin can be a library that others need, by ID and version. Opus loads a library before the plugins that need it, and refuses a plugin whose library is missing or too old, with the reason. The mods list shows what each plugin needs and what uses it.
• Clashes are refused, not forced. A place in the firmware holds one plugin. When two plugins want the same place or the same keys, the one later by file name is refused, and the mods list says which plugin has them.
• Costs up front. The mods list shows each plugin's memory and CPU. Every plugin has a CPU budget in the audio block, and its worst block is measured before release. One that uses far more than it should is switched off, and one that crashes the OP-1 is left out at the next start.
• Your sounds stay. Every preset saved with Opus 1 or 2 names the plugins it needs, by their IDs.

These ideas come from VST3, CLAP, Fabric, Forge, Harmony and Mixin: see docs/design.md and CREDITS.md.

The starter pack

id	what
opus.dimension	synth engine
opus.amp	guitar amp engine, with a tuner
opus.dx	DX7 voice player
opus.outatime	time-travel synth engine
opus.iter	the OP-1's hidden synth engine
opus.bitcrush	effect
opus.chorus	effect
opus.plate	reverb
opus.filter	the OP-1's hidden filter effect
opus.overdrive	a second effect behind every slot
opus.scales	scales and chords
opus.bend	pitch bend
opus.dice	a random sound, and undo
opus.triggerguard	a worn key that fires twice plays once
opus.tapeundo	tape undo and redo
opus.zoom	tape zoom
opus.playpause	play as pause
opus.rename	preset rename
opus.overwrite	overwrite save
opus.splash	your own start-up picture
opus.halloween	colour theme

Outside the pack: opus.bridge (alpha), which runs op1r's .op1p and Hundekraft's .knl synths, effects and sequencers. Versions, keys, CPU and memory for each: https://opus-op1.pages.dev

The names and numbers that 246 mods share inside the firmware are kept in the OP-1 mod registry.

Roadmap

1. The core and its menu (Opus 1)
2. Every feature as a part that registers with the core (Opus 1)
3. Reading plugin files from the OP-1's disk at start-up (Opus 2 beta)
4. The loader, with Opus 1's features moved out into plugin files (Opus 2 beta)
5. Every feature as a file, the description file and a plugin kit for anyone (Opus 2 beta)
6. Out of beta, after enough stress and stability testing

No dates: each step ships when it has run on a real OP-1.

Thanks

TabascoEye, who started it all in 2016, and wavi and op1hacks for op1repacker; popcorp, whose op1r brought the whole scene back to life; RoutineDiscount for the first entry in the mod registry; and everyone in the Custom Firmware thread on op-forums. Where ideas came from: CREDITS.md.

Licence

What's in this repository (the docs and the plugin kit) is GPL-3.0: use it, change it and share it, and what you build on it stays open too. The plugins in the releases are © LizardMan, free to use and share. Their source is not published yet, apart from the kit's four examples. The source of the core and the other plugins will be published once it's properly put together. There's no date yet, but it isn't meant to stay closed. dx contains code under the Apache License 2.0 (its LICENSE and NOTICE are in the starter pack). The firmware updates and the patchers' data are © LizardMan, all rights reserved: please don't share them, link to the website instead.

Opus is an independent project, not affiliated with or endorsed by Teenage Engineering. OP-1 is a trademark of Teenage Engineering AB. There is no firmware in this repository.