node-icy

Node.js module for parsing and/or injecting ICY metadata

This module offers a Reader class for retrieving the raw audio data and parsing the metadata from an ICY stream (commonly SHOUTcast or Icecast broadcasts).

There's also a Writer class that allows you to inject your own metadata into a data stream, which can then be displayed by another ICY client (like VLC).

But you'll probably be most interested in the Client class that builds off of node's core http module, except this version works with servers that return an ICY HTTP version, and automatically sends an "Icy-MetaData: 1" HTTP header to notify the server that we want metadata, and finally it returns a Reader instance in the "response" event, therefore the "res" object also emits "metadata" events. See the example below to see how it works.

A good use case for this module is for HTML5 web apps that host to radio streams; the <audio> tag doesn't know how to deal with the extra metadata and it is impossible to extract (on the client-side). But a WebSocket connection could be used in conjunction with this module to provide those metadata events to a web browser, for instance.

Installation

Install with npm:

$ npm install icy

Example

Here's a basic example of using the HTTP Client to connect to a remote ICY stream, pipe the clean audio data to stdout, and print the HTTP response headers and metadata events to stderr:

var icy = require('icy');
var lame = require('lame');
var Speaker = require('speaker');

// URL to a known ICY stream
var url = 'http://firewall.pulsradio.com';

// connect to the remote stream
icy.get(url, function (res) {

  // log the HTTP response headers
  console.error(res.headers);

  // log any "metadata" events that happen
  res.on('metadata', function (metadata) {
    var parsed = icy.parse(metadata);
    console.error(parsed);
  });

  // Let's play the music (assuming MP3 data).
  // lame decodes and Speaker sends to speakers!
  res.pipe(new lame.Decoder())
     .pipe(new Speaker());
});

API

• Client()
• request()
• get()
• Reader()
• Writer()
  • .queue()
• parse()
• stringify()

Client()

The Client class is a subclass of the http.ClientRequest object.

It adds a stream preprocessor to make "ICY" responses work. This is only needed because of the strictness of node's HTTP parser. I'll volley for ICY to be supported (or at least configurable) in the http header for the JavaScript HTTP rewrite (v0.12 of node?).

The other big difference is that it passes an icy.Reader instance instead of a http.ClientResponse instance to the "response" event callback, so that the "metadata" events are automatically parsed and the raw audio stream it output without the ICY bytes.

Also see the request() and get() convenience functions.

request()

request() convenience function. Similar to node core's http.request(), except it returns an icy.Client instance.

get()

get() convenience function. Similar to node core's http.get(), except it returns an icy.Client instance with .end() called on it and no request body written to it (the most common scenario).

Reader()

ICY stream reader. This is a duplex stream that emits "metadata" events in addition to stripping out the metadata itself from the output data. The result is clean (audio and/or video) data coming out of the stream.

Writer()

The Writer class is a duplex stream that accepts raw audio/video data and passes it through untouched. It also has a queue() function that will queue the Writer to inject the metadata into the stream at the next "metaint" interval.

Writer#queue(metadata)

Queues a piece of metadata to be sent along with the stream. metadata may be a String and be any title (up to 4066 chars), or may be an Object containing at least a "StreamTitle" key, with a String value. The serialized metadata payload must be <= 4080 bytes.

parse()

Parses a Buffer (or String) containing ICY metadata into an Object.

stringify()

Takes an Object and converts it into an ICY metadata string.