A terminal-based step sequencer, drum machine, and synthesizer built entirely in Rust.
All DSP from scratch — no samples, no external audio libraries. Just your terminal and your speakers.
- 8 Drum Tracks — Kick, Snare, Closed HiHat, Open HiHat, Ride, Clap, Cowbell, Tom — each fully synthesized with 8 tweakable sound parameters
- Polyphonic Synth — 2 oscillators + sub, 2 ADSR envelopes, resonant filter, LFO with 6 waveforms, collapsible UI section
- 32-Step Sequencer — 10 patterns and 8 kit slots with per-pattern BPM and swing
- Send Effects Chain — Schroeder reverb, tempo-synced filtered delay, tube saturator, SSL-style glue compressor
- Live Performance — drum pads, real-time recording, pattern queuing, per-pattern BPM
- Mouse Support — click the grid, drag parameters Ableton-style, audition sounds from the activity bar
- Project System — save/load
.tspfiles, standalone kit export, preset browser - Spectrum Analyzer — real-time FFT spectrum display and VU meter with 90s Hi-Fi LED aesthetic
Ships with 10 demo patterns ready to play: House, Chicago House, Brit House, French House, Dirty House, Trance, Techno, Drum & Bass, Trap, and Moombahton.
- Rust 1.70 or later
- macOS with CoreAudio (primary target)
Requires Rust (1.70+). macOS with CoreAudio is the primary target; Linux with ALSA is also supported.
# Clone the repository
git clone https://github.com/illobo/textStep.git
cd textStep
# Build and run (release mode recommended for audio performance)
cargo build --release
cargo run --releaseOn Linux, install ALSA development headers first:
sudo apt-get install libasound2-dev # Debian/UbuntuRun the tests:
cargo test # 23 tests, runs in <1sPre-built binaries for macOS (ARM, x86_64, universal) and Linux (x86_64) are available from GitHub Actions artifacts.
macOS note: Downloaded binaries will be blocked by Gatekeeper. Remove the quarantine flag before running:
xattr -d com.apple.quarantine ./textstep| Key | Action |
|---|---|
Space |
Play / Pause |
Esc |
Stop (reset to step 0) |
- / = |
BPM -1 / +1 |
_ / + |
BPM -10 / +10 |
` |
Toggle record mode |
l |
Toggle loop on/off |
L |
Cycle loop length: 8 / 16 / 24 / 32 |
Shift+C |
Cycle compressor: Off / Light / Medium / Heavy / Max |
| Key | Action |
|---|---|
Tab / Shift+Tab |
Cycle focus: Grid → Controls → Transport |
| Arrow keys | Move cursor in grid or controls |
Enter |
Toggle step (and advance — hold to fill) |
; |
Cycle parameter page: SYN → AMP → FX |
F2 |
Collapse/expand synth section |
~ |
Toggle spectrum analyzer / VU meter |
? |
Help overlay |
Each drum track has 8 parameters across three pages:
| Page | Parameters | Controls |
|---|---|---|
| SYN | Tune, Sweep, Color, Snap | Pitch, timbre, transient character |
| AMP | Filter, Drive, Decay, Volume | Tone shaping, saturation, envelope |
| FX | Reverb Send, Delay Send | Per-track effect routing |
Tweak with Shift+Up/Down (adjust value) or Alt+Up/Down (adjust and audition simultaneously). With the mouse, click-drag any gauge vertically. Alt+R randomizes the current page across all tracks.
Mute (Shift+M) and Solo (Shift+S) are always accessible on any page.
The bottom keyboard row triggers sounds live:
z |
x |
c |
v |
b |
n |
m |
, |
|---|---|---|---|---|---|---|---|
| Kick | Snare | CHH | OHH | Ride | Clap | Cowbell | Tom |
With record enabled and playback running, pad hits write steps at the playhead.
Patterns — 10 slots, each with its own step data and BPM:
| Key | Action |
|---|---|
q w e r t y u i o p |
Queue pattern 1–10 (switches at loop end) |
Shift+ above |
Switch pattern immediately |
[ / ] |
Queue prev / next |
{ / } |
Immediate prev / next |
Kits — 8 slots of sound parameters, shared across patterns:
| Key | Action |
|---|---|
1 through 8 |
Switch to kit slot |
The synth section (toggle visibility with F2) provides a polyphonic synthesizer with 2 main oscillators, a sub-oscillator, noise generator, two ADSR envelopes, a 24dB resonant filter, and an LFO with 6 waveforms. Synth notes are triggered with z x c v when the synth grid is focused, with Up/Down for pitch and ( ) for octave shifts.
| Key | Action |
|---|---|
Ctrl+S |
Save project |
Ctrl+O |
Load project |
Ctrl+N |
Rename current pattern |
Ctrl+K |
Save kit as standalone .tsk file |
Ctrl+J |
Load kit into active slot |
Ctrl+P |
Preset browser |
Ctrl+L |
Pattern browser |
Ctrl+C / Ctrl+Q |
Quit |
Projects are stored as JSON in ~/Library/Application Support/textstep/projects/.
┌──────────────────────────────────────────────────┐
│ UI Thread │
│ ┌────────────┐ ┌──────────┐ ┌──────────────┐ │
│ │ ratatui │ │ crossterm│ │ App State │ │
│ │ renderer │ │ events │ │ (app.rs) │ │
│ └────────────┘ └──────────┘ └──────────────┘ │
│ │
│ crossbeam channels (lock-free, bounded) │
│ ▼ UiToAudio ▲ AudioToUi │
│ │
│ Audio Thread │
│ ┌────────────┐ ┌──────────┐ ┌──────────────┐ │
│ │ Sequencer │ │ Voices │ │ Effects │ │
│ │ Clock │ │ Drum+Syn │ │ Rev/Dly/Comp │ │
│ └────────────┘ └──────────┘ └──────────────┘ │
│ │ │
│ cpal/CoreAudio │
└──────────────────────────────────────────────────┘
Two-thread model:
- UI thread — ratatui + crossterm for rendering and input at ~60fps
- Audio thread — cpal/CoreAudio callback running all DSP per-sample
Communication is lock-free via bounded crossbeam channels. The audio thread never blocks.
Every sound is synthesized in real-time with no external DSP dependencies:
- Drum voices — TR-808/909-inspired kicks (sine + pitch envelope + resonant impulse), noise-blended snares, 6-oscillator metallic banks for hats and rides (Mutable Instruments Plaits-style inharmonic ratios), ring-modulated open hats, bandpass claps, detuned pulse cowbells, FM toms
- Synth voice — dual oscillators, sub, noise, two ADSR envelopes, resonant SVF filter, 6-waveform LFO
- Effects — Schroeder/Freeverb reverb (4 comb + 2 allpass), tempo-synced filtered delay, asymmetric tube saturator, feedforward RMS glue compressor with soft knee
- Primitives — 1-pole HP/LP filters, state-variable filter, xorshift32 noise, tanh waveshaping
| Directory | Purpose |
|---|---|
src/ |
Core: entry point, app state, input handling, messages |
src/ui/ |
Rendering: layout, theme, grids, knobs, transport, spectrum |
src/audio/ |
DSP: engine, clock, drum/synth voices, effects, mixer, FFT |
src/sequencer/ |
Data: patterns, transport, project serialization |
src/presets/ |
Preset browser: drum/synth sounds and patterns by genre |
Hardware/synthwave aesthetic — all rendered with UTF-8 block characters on a dark background.
| Color | Hex | Usage |
|---|---|---|
| Amber | #e8a838 |
Active steps, gauge fills, primary data |
| Cyan | #61dafb |
Transport state, beat LEDs, playhead, focused borders |
| Pink | #ff6b9d |
Focus/selection, current track, record |
| Gold | #ffd700 |
Queued patterns, warnings |
| Crate | Version | Purpose |
|---|---|---|
ratatui |
0.29 | TUI rendering framework |
crossterm |
0.28 | Terminal backend (events, raw mode) |
cpal |
0.15 | Cross-platform audio I/O (CoreAudio) |
crossbeam-channel |
0.5 | Lock-free bounded MPSC channels |
serde + serde_json |
1 | Project serialization (JSON) |
No other runtime dependencies.
textStep/
├── src/
│ ├── main.rs # Entry point, thread spawning, event loop
│ ├── app.rs # Application state, focus, modals
│ ├── keys.rs # Keyboard input handler
│ ├── mouse.rs # Mouse input handler (mirrors UI layout)
│ ├── messages.rs # Cross-thread message enums
│ ├── params.rs # Shared effect parameters
│ ├── ui/
│ │ ├── mod.rs # Top-level render dispatch
│ │ ├── layout.rs # Layout constants (single source of truth)
│ │ ├── theme.rs # Color palette and styling
│ │ ├── transport_bar.rs # Transport controls rendering
│ │ ├── drum_grid.rs # 8×32 drum step grid
│ │ ├── synth_grid.rs # Synth step grid with note display
│ │ ├── knobs.rs # Drum parameter sliders
│ │ ├── synth_knobs.rs # Synth parameter groups
│ │ ├── waveform.rs # Spectrum analyzer / VU meter
│ │ ├── splash.rs # Boot animation
│ │ └── help_overlay.rs # Keyboard shortcut reference
│ ├── audio/
│ │ ├── engine.rs # Audio callback and voice management
│ │ ├── clock.rs # Beat/step timing with swing
│ │ ├── drum_voice.rs # 8 drum synth voices (all DSP)
│ │ ├── synth_voice.rs # Polyphonic synth DSP
│ │ ├── effects.rs # Reverb, delay, compressor, saturator
│ │ ├── mixer.rs # Channel mixing, mute/solo
│ │ ├── display_buffer.rs # Lock-free audio→UI waveform buffer
│ │ └── fft.rs # FFT for spectrum analyzer
│ ├── sequencer/
│ │ ├── drum_pattern.rs # Drum pattern data (8 tracks × 32 steps)
│ │ ├── synth_pattern.rs # Synth pattern data and parameters
│ │ ├── transport.rs # Transport state (BPM, play, swing)
│ │ └── project.rs # Project serialization (.tsp JSON)
│ └── presets/
│ ├── mod.rs # Preset browser state machine
│ ├── drum_presets.rs # Drum sound presets
│ ├── synth_presets.rs # Synth sound presets
│ ├── pattern_presets.rs # Drum pattern presets by genre
│ └── synth_pattern_presets.rs # Synth pattern presets
├── assets/
│ └── demo.gif # Demo recording
├── Cargo.toml
├── BLUEPRINT.md # Full technical documentation
└── LICENSE # GPL v2
Contributions are welcome! Please ensure:
- All tests pass:
cargo test - Code compiles without warnings:
cargo build --release - Follow the existing code style and comment conventions
See BLUEPRINT.md for full technical documentation and architecture details.
This project is licensed under the GNU General Public License v2.0.
Built with Rust · All DSP from scratch · Zero audio dependencies