README.md

Polyphonic Synthesizer Project

A C++ polyphonic synthesizer capable of generating sound, processing MIDI input in real-time, and playing MIDI files. This project demonstrates various synthesis techniques including oscillators, filters, envelopes, LFOs, and effects.

Features

• Polyphonic Voice Architecture: Supports multiple simultaneous voices.
• Oscillators: Multiple waveform options (Sine, Saw, Square, Triangle, Pulse, Additive).
  • Pulse Width Modulation (PWM).
  • Oscillator Sync.
  • Cross-modulation (FM).
• Filters: Multiple filter types (LPF24, LPF12, HPF12, BPF12, Notch) with resonance and key-following.
• Envelopes: ADSR envelopes for amplitude and filter.
  • Velocity sensitivity for envelopes.
• LFO: Low-Frequency Oscillator for modulating various parameters (pitch, pulse width, filter cutoff).
• Modulation:
  • Polyphonic modulation matrix (Filter Env to Osc Freq/PW, Filter Env to Filter Cutoff, Osc B to Osc PW/Filter Cutoff).
  • Modulation wheel assignable to LFO or Noise, targeting oscillator pitch, pulse width, or filter cutoff.
• Effects:
  • Built-in Reverb effect.
  • Mixer Drive and Post Gain per voice.
• MIDI Control:
  • Real-time MIDI input for notes, pitch bend, and modulation wheel.
  • MIDI file playback.
• Parameter Management:
  • Load synth parameters from a JSON file.
  • Defaults to a basic strings sound if no JSON file is found.
• Analog Drift Simulation: Optional pitch and pulse width drift for a more analog character.
• Unison Mode: Stack voices for a thicker sound with detune and stereo spread.
• Glide/Portamento: Smooth pitch transitions between notes.

Dependencies

This project relies on the following external libraries:

• PortAudio: For cross-platform audio I/O.
  • Website: http://www.portaudio.com/
• RtMidi: For cross-platform real-time MIDI input.
  • Website: https://www.music.mcgill.ca/~gary/rtmidi/
• Midifile (by Craig Stuart Sapp): For reading and parsing Standard MIDI Files.
  • GitHub: https://github.com/craigsapp/midifile
  • License: Public Domain (or similar highly permissive license). Included in this repository for convenience.
• nlohmann/json: For parsing JSON parameter files.
  • GitHub: https://github.com/nlohmann/json
  • License: MIT License. Included in this repository (single header file include/nlohmann/json.hpp).

Building the Project

Prerequisites

Ensure you have the following installed:

• A C++17 compliant compiler (e.g., GCC, Clang).
• Make.
• PortAudio development libraries:
  • macOS (Homebrew): brew install portaudio
  • Linux (Debian/Ubuntu): sudo apt-get install portaudio19-dev
• RtMidi development libraries:
  • macOS (Homebrew): brew install rtmidi
  • Linux (Debian/Ubuntu): sudo apt-get install librtmidi-dev

The Midifile and nlohmann/json libraries are included in this repository.

Compilation

1. Clone the repository:

   git clone https://github.com/littlebuddha-dev/synth.git
   cd synth

   If you cloned a version that uses Git submodules for Midifile, you would need:

   git clone --recurse-submodules https://github.com/littlebuddha-dev/synth.git
   cd synth

2. Compile the project using Make:

   make

   This will create an executable named synth in the current directory.

   If you encounter issues, you might need to adjust include paths or library linking flags in the Makefile to match your system's configuration. For macOS, ensure RtMidi is linked with CoreMIDI.framework.

Running the Synthesizer

The synthesizer executable is run from the synth directory.

./synth [path_to_params.json] [path_to_song.mid] [midi_input_port_number]

exsample: ./synth synth_params.json test_song.mid