CmdSynth

CmdSynth is a command-line synthesizer built to generate tones based on user input. It supports all four basic wavetypes (sine, square, sawtooth, and triangle) and it currently only supports outputs in the format of .wav files. CmdSynth also comes with a built-in sequencer mode where a text file containing the sequence data can be read and synthesized into a single .wav file.

Installation

Download the project files from the GitHub repository:

git clone https://github.com/AndrewLockett03/cmdsynth.git

Navigate to the project directory, then:

make

This is meant to work on linux and macOS systems with g++

Usage

CmdSynth supports two current modes: single note generation and sequencer mode.

It can be used as a command line tool as described below, or can be used as a library and run via a custom script.

Single Note Generation

To generate a single note, use the following command:

./cmdsynth <sample_rate> <waveform_type> <cutoff> <note_name> <duration>

For example, to generate a 440 Hz sine wave for 2 seconds at a sample rate of 44100 Hz with a cutoff frequency of 16000 Hz, you would run:

./cmdsynth 44100 1 16000 A4 2

Where the waveform types are defined as: 1 - Sine Wave 2 - Square Wave 3 - Sawtooth Wave 4 - Triangle Wave

Output is saved as: recording.wav in ./data directory.

Sequencer Mode

To use the sequencer mode, create a text file with the following format:

<note_name> <duration>
<note_name> <duration>
<note_name> <duration>
...

note_name should be in the format of A4, C#5, Db2 etc., or to generate silence, put S as the note name.

Duration is measured in seconds.

For example, a simple C major scale with rest in between notes could be represented as:

C3 0.5
S 0.5
D3 0.5
S 0.5
E3 0.5
S 0.5
F3 0.5
S 0.5
G3 0.5
S 0.5
A3 0.5
S 0.5
B3 0.5
S 0.5
C4 0.5

To generate the audio based on a sequence file, use the following command:

./cmdsynth <sample_rate> <waveform_type> <cutoff> <input_file>

For example:

./cmdsynth 44100 3 12000 test_sequence.txt

Output is saved as: recording.wav in ./data directory.

Dependencies

CmdSynth relies on standard C++ libraries and does not require any external downloads. Its wav file handling is done through dr_wav (https://github.com/mackron/dr_libs) by David Reid. This is a one-file library included in the project that simplifies reading and writing to wav files.

Future Improvements

• Add support for ADSR envelopes
• Implement realtime playback
• Add support for midi file ingestion
• Add independent gain to each note in sequencer mode