Odin 2 for MPC

Odin 2, TheWaveWarden's semi-modular synthesizer, as a native VST2 instrument for Akai MPC OS standalone devices (built for a Gen 1 MPC Live II), with its own touchscreen pages in Odin's look. It is built with the mpc-vst-plugins kit.

This is Odin's own sound engine (oscillators, filters, envelopes, LFOs, mod matrix, arpeggiator, effects), compiled for the MPC's ARM processor without JUCE. Odin's 261 factory patches are built in and load exactly as Odin loads them (checked patch by patch against Odin's own patch reader, tools/engine_test.sh).

What's on the MPC

Five pages, laid out for playing standing up on a 4-knob MPC (Live II): each page is four columns of four big knobs, and each column is one Q-Link column, so the four Q-Links turn exactly the four knobs outlined on screen (press the Q-Link button to move to the next column). Knobs carry a ring in Odin blue that shows their position from across the room; names and values are drawn large. Choices you set and leave (types, routing, play mode) are in the panel on the right, where MPC's Q-Link panel slides in while you turn a Q-Link.

• Top bar (every page): ECO and its light, the patch browser (◀ name ▶, also in MPC's PRESET menu), VOICES (how many voices the patch can sound right now; Odin sets it, see below), the CPU meter, STOP.
• MAIN: Voice (master, glide, unison detune and width), Filter 1 (cutoff, resonance, envelope, key follow, and its type), the amp envelope, Space (delay and reverb amounts, with their on buttons). Right: play mode, unison voices, velocity, bend range, arpeggiator.
• OSC: oscillators 1–3 (volume, SHAPE, octave, semitone; the type picker on top), fine tune for all three plus TUNE A4, the master tune (415–465 Hz, 440 in the middle; it belongs to the plugin, so it stays when you change patches, and is saved with the project; new notes take it). Glide is on MAIN. SHAPE turns whatever matters for the oscillator's type and is named after it: PW (analog), POSITION (wavetable, multi), VECTOR X, FM/PM AMOUNT, LOWPASS (noise). Each type's extra choice sits under its knobs (analog wave, wavetable, chip wave and noise, FM/PM ratios, vector Y, noise high-pass). Right: unison.
• FILTER: filters 1 and 2 (per voice) and 3 (on the stereo sum): cutoff, resonance, envelope, key follow, plus velocity and the type's own control (SEM shape, formant vowel, ring-mod amount); Drive (filter saturation, distortion amount and mix). Right: routing (which oscillators feed each filter, filter 1 into 2, which filters reach the amp) and the distortion type.
• ENV: amp, filter and mod envelopes (A/D/S/R), the four LFO rates. Right: the LFO waves.
• FX: delay, reverb, chorus, phaser, each with its on button. Right: flanger.

Left out because they are awkward on a touchscreen or rarely touched live (the patch still has them, factory patches set them, projects keep them): the mod matrix, the arpeggiator's step editor, drawing waveforms, vector corner waves, FM/PM carrier and modulator waves, LFO sync, effect order, per-filter gain, amp pan and gain, the reverb EQ and the delay's high-pass and ducking.

CPU meter, VOICES, ECO and STOP

The MPC gives a plugin about 2.9 ms to make each block of 128 samples, shared with everything else in the project. Odin computes every voice live, so a big patch with many notes held can run out of time and crackle. Since 1.3 Odin looks after this itself; there is no voices knob to turn.

• CPU shows how much of that block time Odin uses, averaged over about a tenth of a second (so a single busy moment, like a chord starting, doesn't read as an overload), then held and falling slowly. Green is fine; amber (60–80 %) is getting busy; red is where a busy project will start to crackle. It only updates a few times a second, so the meter itself costs next to nothing.

• VOICES shows how many voices the current patch may sound at once. Odin works it out: every factory patch was measured (calibrated on a Live II: Antarctica [RS], 4 voices at audio rate = 80 % on the meter), and while you play it follows what each voice really costs, so the voices fill about three quarters of the block and no more. A light patch gets 16 voices, a heavy one as few as 3 or 4. Your own edits are measured the same way.

  • Notes held count as voices, and so do notes still releasing; a unison patch uses several voices per note.
  • When a chord needs more voices than there are, a unison patch plays its chord notes with fewer unison voices each instead of dropping notes (ECO Auto, Eco and Lite); past that, the oldest note gives way, as on any synth.
  • If the load still climbs toward the limit (an edit that makes the patch heavier, a busy project), the oldest note fades out in 15 ms before anything crackles, and VOICES drops. It comes back up by itself once the load is low again.

• ECO chooses how much Odin may simplify to fit more voices:

  Setting	What it does
  Off	each voice exactly as Odin plays it (still within the voice budget)
  Auto (default)	modulation, oscillator pitch and filter cutoff worked out every 8 samples instead of every sample (5.5 kHz, about a quarter less work, as good as inaudible); envelopes, LFOs, FM/PM and the audio itself stay per sample. If Odin's load still climbs past the voice budget (about 85 %), new notes also start with at most 3 unison voices (2 above about 95 %, 1 if Odin runs out of time altogether), back to the full patch after 1.5 s of low load. Notes already playing are never changed
  Eco	modulation every 16 samples (about a third less work) and at most 3 unison voices per note: very close to the original, about half the CPU on the heaviest patches
  Lite	as Eco, at most 2 unison voices, and the per-voice distortion without oversampling: slightly harsher distortion on high notes

  A patch that modulates from an oscillator or filter output (audio-rate modulation in the mod matrix) always runs per sample. The light next to ECO is on while ECO is cutting unison or the distortion's oversampling. ECO is saved with the project and stays as you set it when you change patches.

• STOP silences everything at once: every voice, held notes, the arpeggiator, and the delay and reverb tails.

Build (Ubuntu, Docker)

Put this folder next to your mpc-vst-plugins checkout, in the same Ubuntu folder you build the other ports from:

~/mpc-vst-plugins
~/odin2-mpc

Then:

cd ~/odin2-mpc
./build.sh

That runs the kit's tools/build_port.sh (the armhf compile in the arm32v7/gcc:11-bullseye container, the skin in the mpc-vst-html-art container) and packages the result with the kit's tools/release.py as dist/Odin-2-1.3.0-mpc-armv7.zip. The first build is slow (allow 20–40 minutes): the compiler runs under ARM emulation, and Odin's wavetable data is one very large file. If mpc-vst-plugins is somewhere else, run MPC_VST=/path/to/mpc-vst-plugins ./build.sh.

Install on the MPC

The zip has an installer that stops MPC, backs up MPC.settings, installs the plugin folder into /sdcard/Synths, registers it and starts MPC again. Save your project first. From Ubuntu, with the MPC's IP address:

cd ~/odin2-mpc/dist
unzip Odin-2-1.3.0-mpc-armv7.zip
scp -r Odin-2-1.3.0 root@<mpc-ip>:/tmp/
ssh root@<mpc-ip> sh /tmp/Odin-2-1.3.0/install.sh

INSTALL.md in the zip has the same steps and the manual ones (copy the folder, edit MPC.settings yourself with MPC stopped). The plugin shows up as Odin 2 (manufacturer 3dthc) in MPC's plugin browser. ssh root@<mpc-ip> sh /tmp/Odin-2-1.3.0/uninstall.sh removes it again.

First test on the device

1. Insert Odin 2 on a track and play a few notes (the Init patch).
2. Step through some patches with ◀ ▶ and from the PRESET menu.
3. Hold a big chord on a heavy patch (Antarctica [RS], Alien Chaos2): VOICES shows what it allows, CPU stays out of the red, and it plays without crackling.
4. Press STOP while a long reverb/delay tail is ringing.
5. On OSC, turn TUNE A4 away from 440 Hz and play: the pitch follows; change patch, it stays.
6. Turn every page and the Q-Links; change an oscillator and a filter type and check the panel follows.
7. Save the project, reload it, and check the patch, your edits and the tune came back.

Folder

Path	What
build.sh	build and package (above)
vst/vst.json	the port's build description for mpc-vst-plugins
vst/make_params.py → vst/params.json, src/odin_mpc_params.inc	the controls the MPC sees and the Odin state each drives
vst/make_skin.py → vst/layout.conf, vst/art/gen/	the pages, drawn from Odin's artwork in vst/art/odin/
src/odin_mpc.cpp	the engine the kit's VST2 wrapper drives: controls, patches, project state, voice budget, ECO, STOP, CPU meter
src/odin_state.h	a patch as text lines (the bank and the project state store differences)
src/presets/	the factory bank, generated by tools/make_bank.sh from presets_src/, and each patch's measured load (bank_cost.inc, generated by tools/patch_cost.sh)
src/odin/	Odin 2's engine, vendored; what changed is in src/VENDORED.md
tools/engine_test.sh	offline engine test (bank vs Odin's loader, state round trip, STOP, ECO, voice budget, timings)
tools/patch_cost.sh	measures every factory patch's load and writes src/presets/bank_cost.inc

Regenerate after editing: python3 vst/make_params.py (parameter list), python3 vst/make_skin.py (pages, needs Pillow), tools/make_bank.sh (bank, then tools/patch_cost.sh for its costs). Keep the parameter order: projects store values by position; add new controls at the end of make_params.py.

Licences

GPL-3.0-or-later (LICENSE), as Odin 2. Odin 2 and its artwork and patches are by TheWaveWarden and contributors. The Aldrich font is under the SIL Open Font License (vst/art/fonts/OFL.txt). Surge's tuning library is MIT.