Since the initial music-pipe-rs post, the project has grown. There’s now a web demo with playable examples, a new seq stage for explicit note sequences, and multi-instrument arrangements that work in GarageBand.

Resource Link
Video YouTube
Live Demo music-pipe-rs Samples
Source GitHub
Previous Unix Pipelines for MIDI

Web Demo

The live demo showcases pre-built examples with playable audio:

Tab Style Description
Bach Toccata (Organ) Classical Multi-voice church organ with octave doubling and pedal bass
Bach Toccata (8-bit) Chiptune Gyruss-inspired arcade version with square wave
Bach-esque Algorithmic Procedurally generated baroque-style background music
Baroque Chamber Ensemble Six-channel piece with strings, harpsichord, and recorder

Each tab shows the pipeline script alongside playable audio. See exactly what commands produce each result.

The seq Stage

The new seq stage allows explicit note sequences instead of algorithmic generation:

seed | seq "C4/4 D4/4 E4/4 F4/4 G4/2" | to-midi --out scale.mid

Notation: NOTE/DURATION where duration is in beats. Combine with other stages:

seed | seq "D5/4 C#5/8 R/4 B4/4" | transpose --semitones 5 | humanize | to-midi --out melody.mid

The R represents rests. This enables transcribing existing melodies or composing precise phrases.

Multi-Instrument Arrangements

The Baroque chamber piece demonstrates six-channel composition:

{
    seed 42 | seq "..." --ch 0 --patch 48;  # Strings melody
    seed 42 | seq "..." --ch 1 --patch 6;   # Harpsichord
    seed 42 | seq "..." --ch 2 --patch 74;  # Recorder
    # ... additional voices
} | humanize | to-midi --out baroque.mid

Each instrument gets its own channel and General MIDI patch. The same seed ensures timing coherence across parts.

GarageBand Integration

Import the MIDI files directly into GarageBand:

  1. Generate arrangement: ./examples/trio-demo.sh
  2. Open GarageBand, create new project
  3. Drag the .mid file into the workspace
  4. GarageBand creates tracks for each channel
  5. Assign software instruments to taste

The demo includes a jazz trio arrangement:

  • Piano: Bluesy melody with chords and swing
  • Bass: Walking bass line with acoustic bass patch
  • Drums: Hi-hat, snare, kick with dynamic variation

All generated from pipeline scripts.

Inspiration

This project was inspired by research into generative music tools and techniques:

References

Topic Link
Analog Synthesizers Code Self Study
Drum Synthesis JavaScript Drum Synthesis
Generative Music Code Self Study
Music Projects Software and Hardware
FOSS Music Tools Open Source Music Production
Eurorack Programming Patch.Init() Tutorial
Opusmodus Algorithmic Composition in Lisp

The key insight from Opusmodus: algorithmic composition isn’t random music—it’s programmable composition. Motif transformation, rule systems, deterministic generation. music-pipe-rs brings these ideas to Unix pipes.

What’s Next

The pipeline architecture makes extension natural:

  • More generators: Markov chains, L-systems, cellular automata
  • More transforms: Inversion, retrograde, quantization
  • Live mode: Real-time MIDI output with clock sync

Each new capability is just another stage in the pipeline.

Series: Personal Software (Part 5) Previous: music-pipe-rs: Unix Pipelines

Disclaimer

You are responsible for how you use generated audio. Ensure you have the appropriate rights and permissions for any commercial or public use. This tool generates MIDI data algorithmically—how you render and distribute the final audio is your responsibility.

Be aware that algorithmic composition can inadvertently produce sequences similar to existing copyrighted works. Whether you use this tool, AI generation, or compose by hand, you must verify that your output doesn’t infringe on existing copyrights before public release or commercial use. Protect yourself legally.