peterc/coopiano

A physically modelled piano synthesizer in C++17. It renders notes and MIDI files to stereo WAV and supports live MIDI input on macOS. Sound is synthesized from a hammer, string, soundboard and sympathetic-resonance model, with a room reverb effect. No piano samples, downloads or third-party libraries are required.

You need a C++17 compiler and Make. On macOS, install the Xcode Command Line Tools (xcode-select --install) if they are not already available, then run:

make
./coopiano --help

macOS builds link the system CoreMIDI, AudioToolbox, CoreFoundation and CoreAudio frameworks. The source also supports offline rendering on other platforms with a C++17 compiler and threads; live MIDI/audio is macOS-only. This extraction was built and tested on macOS; other platforms have not been verified here.

Compiler settings can be overridden, for example make CXX=clang++ CXXFLAGS=-O3. Run make clean before changing compiler settings. make clean removes only the executable, preserving any renders and presets.

# Note, velocity, duration, optional key-hold time (seconds)
./coopiano A4 0.5 8
# Writes A4_gp.wav; quote sharp note names, e.g. 'G#3'.

# Built-in musical demo; writes demo_piano.wav
./coopiano demo

# Render your own MIDI file; no MIDI files are bundled
./coopiano performance.mid 1.0 performance.wav

# Play from connected MIDI sources or the virtual coopiano MIDI destination
./coopiano live
# macOS only; Ctrl-C to stop

Running ./coopiano without arguments renders A4 at velocity 0.5 for eight seconds. Offline commands write 44.1 kHz, 16-bit stereo WAV files; they do not play them automatically. On macOS, use afplay A4_gp.wav to listen. Each offline render is peak-normalized independently.

Built-in defaults work without any configuration file. default.ini documents the available voicing and reverb controls, including their ranges. Copy it, edit the copy, then select it explicitly:

cp default.ini my-piano.ini
./coopiano --preset my-piano.ini live
./coopiano --preset my-piano.ini audition --output audition.wav

The audition command plays a chord at increasing velocities. Use --help for its chord, velocity and timing options. Editing default.ini alone does not change the built-in sound; pass --preset and restart playback to load changes.

GP_NO_REVERB=1 ./coopiano A4 0.5 8
GP_SAVE_SETTINGS=1 ./coopiano --preset my-piano.ini A4 0.5 8

GP_SAVE_SETTINGS=1 writes a resolved preset beside the WAV as A4_gp.wav.ini. Environment overrides take precedence over preset settings.

• coopiano.cpp: CLI, MIDI file parser, WAV writer and macOS live host.
• piano.hpp: header-only synthesis library in namespace piano.
• instrument.hpp: voice pool, note/pedal scheduling and instrument effects.
• streaming_soundboard.hpp: streaming soundboard convolution.
• preset.hpp and reverb.hpp: INI configuration and stereo room effect.
• piano_host.hpp and piano_resampler.hpp: host-rate adaptation and resampling.
• live_diagnostics.hpp and live_bench.hpp: support compiled into the macOS host.

The C++ source/header files originate from the development project. Historical comments may refer to documentation in that larger project. The original test and benchmark collections are not bundled here.

MIT. See LICENSE.