Open Synth v2.2.0

Fixed

• User presets are keyed by parameter ID. user_presets.json used to key values by display name, and 68 parameters share only 45 names, so one value drove several parameters (On toggled all three FX slots and the arpeggiator; osc waveforms/volumes and the amp/filter envelopes were coupled). Saving now writes stable parameter IDs. Old display-name presets still load.

Added

• Import presets button in the preset browser: pick a JSON file (an array of presets, one preset, or {"presets": [...]}) and it is merged into your user presets. Presets with the same name are replaced.
• user_preset_test: ID round trip, legacy loading, and import merge.

Downloads are unsigned

Windows SmartScreen: click More info, then Run anyway. macOS Gatekeeper: right-click the .pkg and choose Open, or run xattr -dr com.apple.quarantine on the installed bundles. See the README for details. Check downloads with sha256sum -c SHA256SUMS --ignore-missing.

Open Synth v2.1.0

Installers, signing hooks, and a demo.

Added

• Installers built in CI for every release tag:
  • Windows: an Inno Setup setup.exe. VST3 goes to Common Files\VST3, CLAP to Common Files\CLAP and the standalone to Program Files\Open Synth, and each component is optional.
  • macOS: a universal (arm64 + x86_64) .pkg inside a .dmg, with AU (new), VST3, CLAP and the standalone app.
  • Linux: a .tar.gz with install.sh (~/.vst3, ~/.clap, ~/.local/opt/open-synth, launcher, desktop entry, --uninstall), plus an AppImage of the standalone.
  • SHA256SUMS for all release assets, published by a single release job.
• Optional code signing: Authenticode on Windows, and Developer ID with the hardened runtime, a signed pkg and notarytool notarization on macOS. These steps run only when the signing secrets are configured, and are skipped cleanly otherwise. The README lists the secrets.
• Demo: demo_render, a headless offline renderer that plays a scripted phrase through six factory presets. It produced the demo in docs/media/open-synth-demo.{mp3,ogg}. There is also a README screenshot of the standalone running on Linux.
• CI smoke test on Linux: installs the tarball into a temporary home and runs the standalone under Xvfb.
• Instrument browser quick categories: one-touch Juno-Di style buttons (All / Piano / Organ / Drums / Bass / Pads) above the preset list; the dropdown now lists the real library categories, derived from the 5,600-preset library instead of a stale hardcoded list.
• Keyboard navigation in the preset browser: Up/Down auditions presets live, Enter loads and closes, Escape closes, Left/Right cycles categories when the list has focus.
• Now-playing state: the browser header shows the currently loaded instrument, its row is highlighted in neon yellow with a ▶ marker, and opening the browser preselects and scrolls to it.
• preset_browser_test: headless UI-logic tests covering category switching, keyboard navigation, and loaded-instrument state.

Changed

• Plugins now find the samples bundled inside or beside their own VST3/CLAP/AU file, as well as in a shared ProgramData//Library location. Previously the samples had to be copied by hand into the user data folder.
• On macOS the samples live in Contents/Resources instead of Contents/MacOS, so the bundles can be code-signed.

Fixed

• Category filter matched almost nothing: the dropdown used title-case names ("Pads", "Keys") while the library uses snake_case ("synth_pad"). Filters now match whole words against normalized categories, so "Pad" covers synth_pad, "Piano" covers upright_piano/synth_piano, etc.
• Filtered user-preset lists loaded the wrong preset — the selected display row was used as an index into the unfiltered user-preset array.
• Category dropdown opened with nothing selected; it now defaults to "All Categories".

Downloads are unsigned

Windows SmartScreen: click More info, then Run anyway. macOS Gatekeeper: right-click the .pkg and choose Open, or run xattr -dr com.apple.quarantine on the installed bundles. See the README for details. Check downloads with sha256sum -c SHA256SUMS --ignore-missing.

v2.0.2

Full Changelog: v2.0.1...v2.0.2

v2.0.1 — The Static Hotfix 🎹🦞

Changelog

All notable changes to Open Synth are documented here.

[2.0.1] — 2026-07-25

The "static" hotfix. Three compounding audio bugs that produced noise/drone under presets — most audibly a harsh static behind the Grand Piano.

Fixed

• Filter explosion (the static): the Chamberlin SVF went unstable above sr/6 (8kHz @ 48kHz). Any preset with cutoff > 8kHz (piano @ 12kHz) drove the filter into runaway feedback, railing the mix into square-wave noise. Replaced with a TPT (Zavalishin) SVF — stable up to Nyquist.
• Voice envelopes ignored presets: noteOn never copied the part's envelope into the voice, so every voice used default sustain 0.8 and droned under the decaying samples. Envelopes (amp/filter/pitch + curves) now sync from each voice's part every block — covers direct, arpeggiator, and queue-triggered notes, plus live parameter edits.
• Mix clipping: raw voice accumulation (up to ±8 at full polyphony) slammed the tanh limiter. Added 1/√N polyphonic headroom scaling and a 0.85 sample-layer trim.
• Acoustic preset envelopes: piano, upright, guitars, and basses had pad-style envelopes (sustain 0.6–0.7) that droned beneath the samples. Now sustain 0–0.15 with instrument-natural decays (piano 2400ms). All 5,600 presets regenerated.

Added

• engine_render_test: headless full-engine render harness (layer isolation modes, RMS/peak profiling, WAV dump) — the tool that found all of the above.

[2.0.0] — 2026-07-25

The C++ Rewrite. The engine was rebuilt from the Flutter/Dart prototype (v1.1.0 and earlier) into a native JUCE 8 + C++20 application: sub-10ms latency, 16-part multitimbrality, full MFX chain, and a streaming sample ROMpler. Standalone + VST3 + CLAP.

Sound Engine

• Dual oscillators per part — sine, saw, square, triangle, pulse, noise, wavetable
• Wavetable synthesis with 100+ built-in tables and morphing
• Physical modeling mode (body resonance, key click, sympathetic strings)
• Unison voices with detune and stereo spread; FM on both oscillators; sub-oscillator
• Multi-mode filter (lowpass, highpass, bandpass, notch, comb)
• 3 envelopes (amp with delay/hold, filter with key tracking, pitch) with per-stage curves
• 2 LFOs per part — tempo-syncable, fade-in, routable to pitch/filter/amp/pan
• Arpeggiator with 8 patterns, octave range, swing, gate, hold
• 16-part multitimbrality with full MIDI channel separation
• Drum kit with 8 preset kits and a rhythm pattern player (29 patterns across 9 categories, including Afrobeat and Reggae)

Sample Engine (ROMpler)

• Streaming sample player with cubic interpolation, per-voice anti-aliasing, ADSR, pitch bend
• Multi-zone multisample manifests with velocity layers, round-robin, release samples, loop crossfades
• Supports both multi-layer and flat manifest formats with robust sample path resolution
• 8 CC0 sample libraries wired in as git submodules (1,419 zones): 2 pianos, 2 drum kits, 2 basses, 2 guitars

Effects

• 5-slot FX engine (3 MFX + Reverb + Chorus, Juno-Di parity) with 60+ processor types

Presets

• 5,600 factory presets across 20+ categories (generated library with per-category synthesis profiles)
• User preset manager with categories; setlist mode for live performance

App

• Standalone, VST3, and CLAP builds (desktop); synthwave '84 UI
• Real-time stereo oscilloscope, zone editor overlay, phrase sampler, audio recording
• MIDI learn on all parameters, app state persistence, CPU load meter

Fixed for 1.0.0

• Sample manifests silently failed to load — loader only understood the multi-layer format; all 8 shipped manifests use the flat format. The entire ROMpler layer is now functional and test-verified.
• MIDI CC 123 (All Notes Off) left sample voices hanging — sample player now releases; added CC 120 (All Sound Off) instant kill wired through the engine and MIDI wrapper
• ADSR attack test contaminated by prior voices' release tails — new allSoundOff() gives clean scenario isolation
• native/oboe stale gitlink broke git submodule update --init (and fresh --recurse-submodules clones)
• Cabinet simulator potential uninitialized values on out-of-range/NaN parameters
• Member initialization order mismatch in the plugin editor (-Wreorder, UB-class)
• Constructor parameter shadowing JUCE AudioProcessorEditor::processor
• Afrobeat and Reggae rhythm patterns implemented but unreachable — now in the library

Build & Tooling

• JUCE located via -DJUCE_DIR, JUCE_DIR env var, libs/JUCE submodule, or ~/.juce — no more hardcoded absolute paths
• Wired fx_tests (1,021 assertions) and sample_static_test into CMake; all test targets get FLAC support
• Generated preset library header silences expected conversion warnings via diagnostic pragmas (122k → ~800 warnings)
• Removed legacy Flutter/FFI-era dead code (lib/, native/, PortAudio/Oboe FFI sources)
• Tests: 83/83 sample decode, block processing + ADSR + pitch bend, 8/8 manifest renders, 1,021 FX assertions

---

Made by synth with synthclaw 🎹🦞

v2.0.0 — The C++ Rewrite 🎹🦞

Changelog

All notable changes to Open Synth are documented here.

[2.0.0] — 2026-07-25

The C++ Rewrite. The engine was rebuilt from the Flutter/Dart prototype (v1.1.0 and earlier) into a native JUCE 8 + C++20 application: sub-10ms latency, 16-part multitimbrality, full MFX chain, and a streaming sample ROMpler. Standalone + VST3 + CLAP.

Sound Engine

• Dual oscillators per part — sine, saw, square, triangle, pulse, noise, wavetable
• Wavetable synthesis with 100+ built-in tables and morphing
• Physical modeling mode (body resonance, key click, sympathetic strings)
• Unison voices with detune and stereo spread; FM on both oscillators; sub-oscillator
• Multi-mode filter (lowpass, highpass, bandpass, notch, comb)
• 3 envelopes (amp with delay/hold, filter with key tracking, pitch) with per-stage curves
• 2 LFOs per part — tempo-syncable, fade-in, routable to pitch/filter/amp/pan
• Arpeggiator with 8 patterns, octave range, swing, gate, hold
• 16-part multitimbrality with full MIDI channel separation
• Drum kit with 8 preset kits and a rhythm pattern player (29 patterns across 9 categories, including Afrobeat and Reggae)

Sample Engine (ROMpler)

• Streaming sample player with cubic interpolation, per-voice anti-aliasing, ADSR, pitch bend
• Multi-zone multisample manifests with velocity layers, round-robin, release samples, loop crossfades
• Supports both multi-layer and flat manifest formats with robust sample path resolution
• 8 CC0 sample libraries wired in as git submodules (1,419 zones): 2 pianos, 2 drum kits, 2 basses, 2 guitars

Effects

• 5-slot FX engine (3 MFX + Reverb + Chorus, Juno-Di parity) with 60+ processor types

Presets

• 5,600 factory presets across 20+ categories (generated library with per-category synthesis profiles)
• User preset manager with categories; setlist mode for live performance

App

• Standalone, VST3, and CLAP builds (desktop); synthwave '84 UI
• Real-time stereo oscilloscope, zone editor overlay, phrase sampler, audio recording
• MIDI learn on all parameters, app state persistence, CPU load meter

Fixed for 1.0.0

• Sample manifests silently failed to load — loader only understood the multi-layer format; all 8 shipped manifests use the flat format. The entire ROMpler layer is now functional and test-verified.
• MIDI CC 123 (All Notes Off) left sample voices hanging — sample player now releases; added CC 120 (All Sound Off) instant kill wired through the engine and MIDI wrapper
• ADSR attack test contaminated by prior voices' release tails — new allSoundOff() gives clean scenario isolation
• native/oboe stale gitlink broke git submodule update --init (and fresh --recurse-submodules clones)
• Cabinet simulator potential uninitialized values on out-of-range/NaN parameters
• Member initialization order mismatch in the plugin editor (-Wreorder, UB-class)
• Constructor parameter shadowing JUCE AudioProcessorEditor::processor
• Afrobeat and Reggae rhythm patterns implemented but unreachable — now in the library

Build & Tooling

• JUCE located via -DJUCE_DIR, JUCE_DIR env var, libs/JUCE submodule, or ~/.juce — no more hardcoded absolute paths
• Wired fx_tests (1,021 assertions) and sample_static_test into CMake; all test targets get FLAC support
• Generated preset library header silences expected conversion warnings via diagnostic pragmas (122k → ~800 warnings)
• Removed legacy Flutter/FFI-era dead code (lib/, native/, PortAudio/Oboe FFI sources)
• Tests: 83/83 sample decode, block processing + ADSR + pitch bend, 8/8 manifest renders, 1,021 FX assertions

---

Made by synth with synthclaw 🎹🦞

Open Synth v0.1.0 Alpha — First Android Build 🎹

Open Synth — First Android Build

What is this?

Open-source software synthesizer keyboard app — Flutter + C++ DSP via FFI.

This Build

• Debug APK (153MB) with full preset library
• Target: Pixel 8a (landscape recommended)
• Audio: Oboe low-latency backend

Features

• 1,415 factory presets across 8 categories
• 64-voice polyphony, dual oscillators + unison
• 7 FX types: chorus, delay, reverb, phaser, flanger, drive, compressor
• Arpeggiator: 5 patterns, swing, hold/latch, live step LEDs
• 16-step sequencer with per-step note editing + MIDI import
• Mod matrix, macro controls, preset morphing
• Keyboard split and layer modes
• MIDI clock sync + MIDI learn
• Mobile UX: hamburger drawer, landscape split-view

Install

1. Download app-debug.apk
2. Enable Install from unknown sources
3. Install and launch
4. Rotate to landscape for best experience
5. Hamburger menu → Synth to start playing

Architecture

Flutter (Riverpod) --FFI--> C++ Native Engine (SynthEngine, VoiceAllocator, Arpeggiator, OboeAudioStream)

Open Synth v1.1.0 — The Grid Expansion

Ship it. 50 factory presets, full FX chain, and Oboe-powered mobile audio. 🎹🦞