MIDI Banger Generator

A C program that generates randomised backing tracks using concurrent child processes and raw MIDI file construction — no external music libraries required.

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How It Works

The parent process reads user parameters (BPM, genre, key, bars), then spawns 3 child processes concurrently over pipes — one for each instrument. Each child independently generates a MIDI track and pipes it back to the parent, which merges them into a single .mid file and renders it to .ogg via TiMidity++.

                        ┌───────────────────────────┐
                        │       PARENT PROCESS      │
                        │                           │
                        │  Reads: BPM, Genre,       │
                        │         Key, Bars         │
                        └────────────┬──────────────┘
                                     │
                    fork() × 3  +  pipes
                                     │
         ┌───────────────────────────┼─────────────────────────┐
         │                           │                         │
         ▼                           ▼                         ▼
 ┌────────────────┐          ┌────────────────┐        ┌────────────────┐
 │  CHILD: DRUMS  │          │ CHILD: GUITAR  │        │  CHILD: PIANO  │
 │                │          │                │        │                │
 │ Kick, snare,   │          │ Strummed chord │        │ Melodic runs   │
 │ hi-hat pattern │          │ progressions   │        │ chord voicing  │
 └───────┬────────┘          └───────┬────────┘        └───────┬────────┘
         │                           │                         │
         │    MIDI track bytes (via pipe)                      │
         └───────────────────────────┼─────────────────────────┘
                                     │
                                     ▼
                        ┌───────────────────────────┐
                        │       PARENT PROCESS      │
                        │                           │
                        │  Merges 3 tracks into     │
                        │  SMF Type 1 MIDI file     │
                        │                           │
                        │  Calls TiMidity++ to      │
                        │  render → output.ogg      │
                        └───────────────────────────┘

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Genres

#	Genre	Chord Style	Progressions
0	Pop	Triads + 7ths	7 (Classic, Bright, Emotional, Dreamy)
1	Lo-fi	7th chords (jazzy)	10 (Chill, Dreamy, Sad, Neo-Soul)
2	Rock	Power chords + triads	8 (Classic, Dark, Garage Punk)
3	Loony Tunes	Major/minor triads	1 (fixed cartoon progression)

Each genre has custom drum patterns, guitar voicings, piano scales, and instrument patches (General MIDI).

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Requirements

• GCC (C99)
• TiMidity++ — for rendering MIDI to audio

sudo apt install timidity        # Debian/Ubuntu
brew install timidity            # macOS (Homebrew)

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Build & Run

make
./midi_gen

The program is fully interactive. You will be prompted for:

BPM (tempo) [40-240]:
Number of bars [1-64]:
Genre  0=Pop  1=Lo-fi  2=Rock  3=Loony-Tunes
Key root (e.g. C4, G#3, Bb4 — full list shown at prompt)

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Output

File	Description
output.mid	Raw MIDI file (SMF Type 1, 4 tracks)
output.ogg	Rendered audio — open in any media player

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Project Structure

midi_gen.c      — full source (parent + 3 child workers)
Makefile        — builds with: make

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Example Session

╔══════════════════════════════════════╗
║       MIDI Banger Generator          ║
╚══════════════════════════════════════╝

BPM (tempo) [40-240]: 120

Number of bars [1-64]: 8

Genre  0=Pop  1=Lo-fi  2=Rock  3=Loony-Tunes
Genre [0-3]: 2

Key root: G3

──────────────── LOG ────────────────
[Parent] BPM=120  bars=8  genre=Rock  key=55
[Parent] Rock progression: Dark Rock im-bVII-bVI-V
[Drums]  Genre selected: Rock
[Guitar] Genre selected: Rock
[Piano]  Genre selected: Rock
─────────────────────────────────────

╔══════════════════════════════════════╗
║         Banger Generated!            ║
║                                      ║
║   MIDI  ->  output.mid               ║
║   Audio ->  output.ogg               ║
╚══════════════════════════════════════╝