os2l

NodeJS implementation of the Open Sound to Light protocol.

The standard is defined here. This package was only tested on Windows with VirtualDJ.

Installation

npm install os2l

Usage

For servers

Usually the DMX software:

const { OS2LServer} = require("os2l");

// All options are optional
let server = new OS2LServer({
  port: 5000 // TCP Port to listen on
});

// Register events
server.on("error", err => {
  console.error(err);
});

server.on("btnOn", name => {
  if (name == "fog") {
    // ... code for starting a fog machine
    server.feedback("fog", "on");
  }
});

server.on("btnOff", name => {
  if (name == "fog") {
    // ... code for stopping a fog machine
    server.feedback("fog", "off");
  }
});

server.on("beat", data => {
  // Toggle light or something
});

// Start the server
server.start().then(() => {
  console.log("Server is now listening on port: ", server.port);
});

For clients

Usually the audio software:

const {OS2LClient} = require("os2l");

let client = new OS2LClient();
client.on("error", err => console.error(err));

client.on("feedback", data => {
  // Let a button light up or something
});

client.connect().then(() => {
  client.buttonOn("hi");
  client.beat(true, 1, 120);
});

Hosting on Windows

To host on windows, "Bonjour Print Services" or the SDK needs to be installed on the host system. It is needed for DNS service discovery. When addresses and ports are given manually, this is not needed.

I don't like that we need to depend on an Apple product for this to work. A DNS-SD service is already implemented in windows 10 but is not accessible to us. This is a good starting point to dig deeper and maybe find a solution.

Hosting on Linux

To work on Linux, "Avahi" is needed for DNS-SD. (Not tested)

Hosting on MacOS

On MacOS it will work by default. (Not tested)

Limitations

The characters { and } in strings like button names may produce errors during parsing of incoming packet data. However, when starting with an open bracket and matching the count with closing brackets after that should work. So a name like Very{cool}button is still a valid parsable name.

API

OS2LServer

let server = new OS2LServer({
  port: 1806, // Port for the server to listen on
  doPublish: true // (optional) Use DNS-DS?
});

Event: error

Emitted when an error occours. After this event was called the server will stop and needs to be opened manually via server.start().

Event: warning

Emitted when something happens that should not happen but the server can stay open.

Event: connection

Emitted when a connection from a client was made.

Event: closed

Emitted after the server was closed. Is also called when the server stops because of an error.

Event: btnOn

Emitted when a button is pressed. First argument is the name of the button.

Event: btnOff

Emitted when a button is released. First argument is the name of the button.

Event: cmd

Emitted when a command was send by a client. First argument is the received object.

Event: btn

Emitted when a client changes the state of a button. First argument is the received object.

Event: beat

Emitted when a client sends a beat packet. First argument is the received object.

Event: data

Emitted when anything comes from the client. First argument is the received object. This event can be used to extend the protocol.

server.start()

Starts the server

server.stop()

Stops the server

server.feedback(name, state, page)

Sends feedback to all clients. The arguments are defined in the standard.

OSL2Client

let client = new OS2LClient({
  port: 1806, // (optional) The port to connect to
  host: "localhost", // (optional) Hostname of the server
  useDNS_SD: false, // (optional) Use DNS-SD? Is this is set to true, host and port are determined automatically.
  autoReconnect: true, // (optional) Reconnect after connection lost?
  autoReconnectInterval: 1000 // (optional) Milliseconds between tries when auto reconnect in true
});

Event: error

Emitted after an error occours.

Event: connected

Emitted after a connection was made.

Event: closed

Emitted after the connection ended.

Event: feedback

Emitted when the server sends feedback. The arguments are name, state and page. When no page was given this argument is undefined as this argument is optional to the standard.

client.beat(change, pos, bpm)

Sends a beat to the server. Arguments are defined in the standard.

client.buttonOff(name)

Sends a btnOff event to the server. First argument is the name of the button.

client.buttonOn(name)

Sends a btnOn event to the server. First argument is the name of the button.

client.close()

Closes the connection.

client.command(id, param)

Sends a command to the server. id (Integer) is the id of the command and param a number between 0 and 1.

client.connect()

Connects to the server. When no server data is given, this method searches for the server with DNS-SD.

client.custom(object)

Sends a custom object to the server. This method can be used to extend the protocol.

License

MIT