The Architecture of Lambda Music Sequencer

Lambda Music Sequencer(hereinafter abbreviated as Lamu) is merely an Lisp editor built on Scheme interpreter works with JACKAudio client. This can be used as a live-coding environment, or a JACK connection controller which can be executed from your shell. I believe it is a very simple yet effective way to implement DAW in Linux.

I have not tried other live-coding environment such as SuperCollider, Sonic Pi and others; the main difference between them and Lamu is that these environments have sound modules but Lamu does not. Lamu is simply a JACKAudio client. I believe the combination of Scheme and JACKAudio can be a very effective and “Linux”-way to implement a live-coding environment.

The Architecture of Pulsar Sequencer

Lamu consists several layers on its architecture.

Lamu depends on following projects :

• Kawa Scheme A Scheme implementation which is written in Java.
• jna Java Native Access.
• jnajack Java bindings to JACK Audio Connection Kit.

Lamu includes following projects:

• Lamu/Kawapad KawaPad is an Scheme editor which can write and run Scheme code on-the-fly.
  The editor can be extended by Scheme itself. Kawapad has a number of useful features for editing Scheme programs. Kawapad is written in Java and cooperatively works with Kawa Scheme.

• Lamu/KawaHTTP A HTTP interface for Kawa. This allows remote processes to execute any Scheme code remotely.

• Lamu/Metro Metro is a multi-track MIDI sequencer framework which is written in Java. Metro provides a simple framework to build music sequencing systems. Metro encapsulates the access to JACKAudio and offers mechanisms to send notation data to JACKAudio.

• Lamu/Pulsar Pulsar is the main component of this application; Pulsar works as a bridge between Metro and Kawa Scheme. Pulsar also provides several sets of API for Scheme to control JACKAudio and others.

• Lamu The project for Lamu application class which manages command-line parsing, starting up and others.

Lamu Client-Server Mode

Lamu is also be able to run in client-server model. A Java text editor is sometimes a burden for the garbage collection and obstructs JACKAudio’s real-time processing. This causes unpredictable skips on the generated sound.
Therefore, Kawapad is designed that to be able to be separately executed in another JVM from the Java virtual-machine which processing the events of JACKAudio.

This can be invoked by Lamu Command-line parameter. For further information, please read the Lamu Command-line parameter.