Real-time audio programming examples using the JACK Audio Connection Kit and the Odin programming language.

These are ports of the official JACK example clients, demonstrating audio generation, MIDI processing, and audio capture.

1. Install JACK development libraries:

   # Ubuntu/Debian
   sudo apt install libjack-jackd2-dev
   
   # Fedora/RHEL
   sudo dnf install jack-audio-connection-kit-devel

2. Audio server: You need either JACK or PipeWire running. Most modern Linux distributions run PipeWire by default, which provides JACK compatibility.

3. Odin compiler: Download from odin-lang.org

# Build all programs
make all

# Or build individual programs
make simple_client
make midisine
make capture_client
make midiseq

# Run a program
./simple_client

Generates a stereo sine wave output to test your audio setup.

./simple_client

MIDI-triggered sine wave synthesizer. Connect a MIDI controller to hear notes.

./midisine

Note: This Odin version includes a full ADSR envelope (Attack, Decay, Sustain, Release) with smooth legato transitions, unlike the original C version which has no envelope.

Records audio from your microphone/line input to a WAV file.

./capture_client output.wav

A MIDI sequencer that loops a programmed sequence of notes.

# Play C4 at start, D#4 at quarter point in a half-second loop
./midiseq Sequencer 24000 0 60 8000 12000 63 8000

Arguments: <client_name> <loop_samples> <note_on_time> <note> <note_off_time> ...

• loop_samples: Loop length in samples (24000 ≈ 0.5s at 48kHz)
• note_on_time: When to start the note (in samples)
• note: MIDI note number (60 = C4, 63 = D#4)
• note_off_time: When to stop the note (in samples)

To hear sound: midiseq outputs MIDI events, not audio. Connect it to a synthesizer using qjackctl or some other connection tool. You can use ./midisine as the synthesizer - just connect midiseq:midi_out to midisine:midi_in.

Press Ctrl+C to stop (all notes will be turned off cleanly).

An audio metronome with configurable timing and tone characteristics.

# Simple 120 BPM metronome
./metro -b 120

# Custom metronome: 100 BPM, 440Hz tone, 200ms duration
./metro -b 100 -f 440 -D 200 -A 0.8

Options:

• -b, --bpm BPM: Beats per minute (required)
• -f, --frequency FREQ: Tone frequency in Hz (default: 880)
• -A, --amplitude AMP: Amplitude 0-1 (default: 0.5)
• -D, --duration MS: Tone duration in milliseconds (default: 100)
• -a, --attack PERCENT: Attack time as percentage (default: 1.0)
• -d, --decay PERCENT: Decay time as percentage (default: 10.0)

• Use make help to see available build targets
• Check the JACK documentation for audio programming concepts
• See CLAUDE.md for development details