Krate Audio
A monorepo for audio plugins and the KrateDSP library
Overview
This monorepo contains the KrateDSP shared DSP library and audio plugins built on top of it. The architecture enables code reuse across plugins while maintaining a clean separation between DSP algorithms and plugin-specific implementations.
This project is a personal endeavour to investigate how viable it is to develop a DSP library, and VST3 plugins built on top of this library, using AI assisted development.
Repository Structure
krate-audio/
├── dsp/ # KrateDSP - Shared DSP library
│ ├── include/krate/dsp/ # Public headers
│ │ ├── core/ # Layer 0: Math utilities, constants
│ │ ├── primitives/ # Layer 1: Basic DSP blocks (filters, delay lines, LFOs)
│ │ ├── processors/ # Layer 2: Composed processors (filters, saturation, dynamics)
│ │ ├── systems/ # Layer 3: Complex systems (feedback networks, voices, organisms)
│ │ └── effects/ # Layer 4: Complete effect algorithms
│ └── tests/ # DSP unit tests (7200+ test cases, one executable per layer plus an IEEE-only one)
│
├── plugins/
│ ├── iterum/ # Iterum - Delay plugin with 10 modes
│ ├── disrumpo/ # Disrumpo - Multiband morphing distortion
│ ├── ruinae/ # Ruinae - Chaos/spectral hybrid synthesizer
│ ├── innexus/ # Innexus - Harmonic analysis/resynthesis instrument
│ ├── gradus/ # Gradus - Standalone step arpeggiator
│ ├── membrum/ # Membrum - Physically-modelled drum synthesizer
│ ├── seraphis/ # Seraphis - Spectral organism synthesizer
│ ├── vorago/ # Vorago - Dark ambient drone instrument
│ ├── profundum/ # Profundum - Mass bass instrument
│ └── shared/ # Shared plugin infrastructure (UI controls, presets, MIDI, update)
│
├── tools/
│ ├── control_testbench/ # Standalone app for testing custom VSTGUI controls
│ ├── krate-render/ # Offline plugin renderer (audio verification)
│ ├── membrum-fit/ # Offline drum-sample fitter
│ ├── pluginval.exe # Plugin validation tool
│ ├── run-clang-tidy.* # Static analysis runners (ps1/sh)
│ ├── *_preset_generator.* # Factory preset generators
│ ├── lint-*.js # Architecture/ODR/portability lints (run by CI)
│ └── *.js # Dev helpers (crash dump analysis, signal flow, repo maps)
│
├── tests/ # Shared test helpers and DSP benchmarks
├── extern/vst3sdk/ # Steinberg VST3 SDK (submodule)
└── extern/dr_libs/ # dr_wav single-header WAV loader (vendored, public domain)
Every plugin follows the same src/ tests/ docs/ resources/ skeleton. pffft (SIMD FFT, BSD) and Google Highway (SIMD math, Apache-2.0) are fetched by CMake at configure time and land in build/_deps/.
Plugins
A feature-rich VST3/AU delay plugin with 10 distinct delay algorithms - from vintage tape and analog emulations to modern granular and spectral processing.
Website & Documentation | Plugin README
A multiband morphing distortion VST3 plugin with a 4-band crossover network, smooth morph transitions between distortion types, and a sweep system with LFO and envelope modes.
Website & Documentation | Changelog
A chaos/spectral hybrid synthesizer blending 10 oscillator types — from classic PolyBLEP and wavetable to chaos attractors, particle clouds, and spectral freeze — with a deep modulation matrix, full arpeggiator, and a post-voice effects chain.
Website & Documentation | Plugin README
A harmonic analysis and resynthesis VST3/AU instrument. Analyzes audio samples or live sidechain input to extract harmonic content, then resynthesizes it as a playable instrument with independent control over harmonics, residual noise, and transients.
Website & Documentation | Plugin README
A standalone step arpeggiator with 8 independent polymetric lanes plus a MIDI delay lane, per-lane speed multipliers, Euclidean rhythms, conditional triggers, chord generation, and scale quantization. Runs as a VST3 instrument with MIDI output for driving any synth, plus a built-in audition voice. Shares arp parameter IDs with Ruinae for cross-plugin preset exchange.
Website & Documentation | Changelog
A physically-modelled drum synthesizer: 32 pads, 6 exciter types, 6 body models, parallel noise and click layers, head/shell coupling, and 20 factory kits.
Website & Documentation | Changelog
A spectral organism synthesizer: each voice is a 64-partial harmonic cloud driven by a spectral-evolution layer, resonated through a continuous modal body, with a parallel granular atmosphere. Slow autonomous life modulators animate everything, and an integrated Aether space engine (infinite FDN reverb, shimmer bloom, spectral diffusion) sits in the signal path.
Website & Documentation | Plugin README
A dark-ambient drone instrument, Seraphis's subterranean sibling: deep harmonic clouds, sub tones, spectral smear and a cavernous space engine, grown from slow discrete events and emergent agent interaction rather than authored states. Twelve concept macros steer the ecosystem, a live ecosystem view shows what it is doing, and 42 factory presets across seven categories ship with it. Drones take seconds to surface and minutes to swell; that is the instrument, not a fault.
Website & Documentation | Plugin README | Changelog
A bass instrument built around mass rather than layers: one additive harmonic core whose spectrum is regenerated from four controls (Depth, Body, Edge, Spectral Shift), a per-voice Sub Anchor that sits outside every nonlinear stage so the fundamental never disappears, a Mass macro, a frequency-dependent stereo field that keeps the weight centred, and a Bass Morph between two complete sound states. Four Personality macros (Weight, Dark/Bright, Tight/Loose, Clean/Violent), a live harmonic spectrum, Mono and 8-voice Poly modes, and 58 factory presets across six categories ship with it.
Website & Documentation | Plugin README | Changelog
KrateDSP Library
The KrateDSP library provides reusable DSP components organized in a 5-layer architecture where each layer can only depend on layers below it:
| Layer | Directory | Components | Examples |
|---|
| 0 | core/ | 38 math/utility headers | dB conversion, sigmoid functions, interpolation, window functions, RNG |
| 1 | primitives/ | 54 basic DSP blocks | Biquad, SVF, ladder filter, delay lines, LFOs, FFT/STFT, oscillators, smoothers |
| 2 | processors/ | 108 composed processors | Filters (formant, phaser, spectral morph), saturation, resonator bank, particle oscillator, envelope followers |
| 3 | systems/ | 45 complex systems | Tape machine, amp channel, feedback networks, granular engine, synth voices, modulation matrix, spectral organisms, drone ecosystems (Vorago) |
| 4 | effects/ | 15 complete algorithms | Tape delay, granular delay, shimmer, spectral, BBD, reverb, flanger |
Key Features
- Real-Time Safe - No allocations in audio processing, lock-free operations
- Modern C++20 - RAII, constexpr, concepts, value semantics
- Cross-Platform - Windows, macOS (Intel & Apple Silicon), Linux
- Extensively Tested - 7200+ DSP test cases across 320+ test files (10,800+ across the whole repo), spectral analysis, and approval testing
- SIMD-Optimized FFT - pffft backend with SSE (x86/x64) and NEON (ARM) acceleration
- Composable Anti-Aliasing - Oversampling applied at appropriate abstraction levels
- Physical Modeling - Resonator banks, formant filters, waveguide primitives, modal drum bodies
Building
Prerequisites
- CMake 3.20+
- C++20 compiler (MSVC 2022, Clang 14+, GCC 11+)
- VST3 SDK (included as submodule)
Build Commands
# Clone with submodules
git clone --recursive https://github.com/rolandzwaga/krate-audio.git
cd krate-audio
# Configure and build (choose your platform)
cmake --preset windows-x64-release && cmake --build --preset windows-x64-release
cmake --preset macos-release && cmake --build --preset macos-release
cmake --preset linux-release && cmake --build --preset linux-release
# Run all tests
ctest --test-dir build/windows-x64-release -C Release
ctest --test-dir build/macos-release -C Release
ctest --test-dir build/linux-release -C Release
# Run DSP tests only (one executable per layer, plus dsp_ieee_tests for the IEEE-only NaN / Inf and bit-exactness cases)
cmake --build build/windows-x64-release --config Release --target dsp_core_tests dsp_primitives_tests dsp_processors_tests dsp_systems_tests dsp_effects_tests dsp_ieee_tests
./build/windows-x64-release/bin/Release/dsp_core_tests
Build Outputs
| Target | Location |
|---|
| Plugins | build/<preset>/VST3/Release/<Plugin>.vst3 (Iterum, Disrumpo, Ruinae, Innexus, Gradus, Membrum, Seraphis, Vorago, Profundum) |
| DSP tests | build/<preset>/bin/Release/dsp_{core,primitives,processors,systems,effects,ieee}_tests |
| Plugin tests | build/<preset>/bin/Release/<plugin>_tests (Iterum: plugin_tests and approval_tests) |
| Shared infrastructure tests | build/<preset>/bin/Release/shared_tests |
| KrateDSP library | build/<preset>/lib/Release/KrateDSP.lib |
Technical Highlights
- Layered Architecture - Clean dependency hierarchy prevents circular dependencies
- Header-Only DSP - Most DSP code is header-only for inlining and optimization
- Constitution-Driven - Development follows documented principles in
.specify/memory/constitution.md
- Spec-First Development - Features are specified before implementation
License
This project is licensed under the MIT License - see the LICENSE file for details.
Author
Roland Zwaga - Krate Audio
Built with the Steinberg VST3 SDK and VSTGUI
