osc-min

simple utilities for open sound control in node.js

This package provides some node.js utilities for working with OSC, a format for sound and systems control.
Here we implement the OSC 1.1 specification. OSC is a transport-independent protocol, so we don't provide any server objects, as you should be able to use OSC over any transport you like. The most common is probably udp, but tcp is not unheard of.

Examples

Further examples available in the examples folder.

A simple OSC server that prints any received messages

const sock = udp.createSocket("udp4", (msg) => {
  try {
    console.log(osc.fromBuffer(msg));
  } catch (e) {
    console.log("invalid OSC packet", e);
  }
});

sock.bind(inport);

Send a message containing multiple arguments every 2 seconds

const sendHeartbeat = () => {
  const buf = toBuffer({
    address: "/heartbeat",
    args: [
      12,
      "sttttring",
      new TextEncoder().encode("beat"),
      {
        type: "integer",
        value: 7,
      },
    ],
  });
  return udp.send(buf, 0, buf.byteLength, outport, "localhost");
};

setInterval(sendHeartbeat, 2000);

A simple OSC re-director

const sock = dgram.createSocket("udp4", (msg) => {
  try {
    const redirected = osc.applyAddressTransform(
      msg,
      (address) => `/redirect${address}`
    );
    return sock.send(
      redirected,
      0,
      redirected.byteLength,
      outport,
      "localhost"
    );
  } catch (e) {
    return console.log(`error redirecting: ${e}`);
  }
});

sock.bind(inport);

Javascript representations of the OSC types.

See the [spec][spec] for more information on the OSC types.

• An OSC Packet is an OSC Message or an OSC Bundle.

• An OSC Message:

   {
       oscType : "message"
       address : "/address/pattern/might/have/wildcards"
       args : [arg1,arg2]
   }

Where args is an array of OSC Arguments. oscType is optional. args can be a single element.

• An OSC Argument is represented as a javascript object with the following layout:

   {
       type : "string"
       value : "value"
   }

Where the type is one of the following:

• string - string value
• float - numeric value
• integer - numeric value
• color - JS object containing red, green, blue, alpha in range 0-255
• midi - four-element array of numbers representing a midi packet of data
• symbol - string value
• character - a single-character string
• double - numeric value
• bigint - 64-bit bigint value (watch out, this will be truncated to 64 bits!)
• blob - ArrayBuffer, DataView, TypedArray or node.js Buffer
• true - value is boolean true
• false - value is boolean false
• null - no value
• bang - no value (this is the I type tag)
• timetag - Javascript Date
• array - array of OSC Arguments

Note that type is always a string - i.e. "true" rather than true.

The following non-standard types are also supported:

• double - numeric value (encodes to a float64 value)

For messages sent to the toBuffer function, type is optional. If the argument is not an object, it will be interpreted as either string, float, array or blob, depending on its javascript type (String, Number, Array, Buffer, respectively)

• An OSC Bundle is represented as a javascript object with the following fields:

   {
       oscType : "bundle"
       timetag : 7
       elements : [element1, element]
   }

oscType "bundle"

timetag is one of:

• Date - a JavaScript Date object
• Array - [numberOfSecondsSince1900, fractionalSeconds] Both values are numbers. This gives full timing accuracy of 1/(2^32) seconds.

elements is an Array of either OSC Message or OSC Bundle

[spec]: http://opensoundcontrol.org/spec-1_0

Migrating from 1.0

There have been a few breaking changes from the 1.0 version:

• We now provide type declarations for typescript compatibility
• We always enable the previously optional "strict" errors
• Many explicit error messages for passing in data of the wrong type have been removed. We encourage you to use typescript to prevent these sorts of errors.
• Functions that used to return Buffer now return DataView
• TimeTags must be specified as Dates or [number, number] arrays, and are always returned as [number, number] arrays. To convert between arrays and Dates, use dateToTimetag and timetagToDate.
• The two-argument version of toBuffer has been removed.

License

Licensed under the terms found in COPYING (zlib license)