What is fsynth?

It's a simple music synthesizer. It focuses on generating the waveforms from scratch, no samples are used. You can listen to it via the Web player, or using the cross-platform Java CLI. Read on to learn more.

Secondly, this project is my playground for learning Kotlin, functional programming (hence the "f" in "fsynth"), front-end development, Gradle, multiplatform projects, and other. It's also a place where I can focus more on quality than I normally could afford in a professional environment, because here I don't have a pressure to deliver on time. That's why my aim here is also to have as little technical debt as possible, and have as clean code as I can write.

Songs are described with such DSL:

val simpleDemoSong = song(
        name = "Simple demo song",
        beatsPerMinute = 120) {
    track(instrument = organs, volume = 0.3f) {
        note(1 by 8, D4)
        note(1 by 16, Csharp4)
        note(1 by 16, D4)
        note(1 by 8, E4)
        note(1 by 8, D4)

        pause(1 by 8)
        chord(1 by 8, A3, D4, Fsharp4)
        chord(1 by 4, B3, D4, G4)
    }
}

How to listen

Web

https://fsynthlib.github.io/fsynth/

Java CLI

The CLI uses system sound output to play music.

You can use the CLI from the distribution package:

./gradlew :cli:installDist
cli/build/install/fsynth/bin/fsynth --song 'Van Halen - Jump (intro)'

or during development, you can call the CLI through Gradle:

./gradlew :cli:run --args="--song 'Van Halen - Jump (intro)'"

To see a list of available songs, call the CLI without arguments.

Talk on Tricity Kotlin User Group

Build prerequisites

The below dependencies won't be installed by Gradle:

• JDK + path to it in JAVA_HOME (warning: use Oracle's JDK for now, there are some issue with OpenJDK; see #31 for details)
• Android SDK + path to it in ANDROID_HOME