node (socket) live audio stream / broadcast

Question

Please, is there any easy way to stream (broadcast) media file (ogg, mp3, spx..) from server to client (browser) via NODE.js and possibly SOCKET.IO?

I have to record audio input on the server side and then be able to play it realtime for many clients. I've been messing with binary.js or socket.io streams but wasnt able to get it right.

I've tried to encode audio input with speex, vorbis or lame and then load it by FS to client but I havent been successful. Or do i have to capture PCM and then decode it in browser?

Any suggestion on this, nothing Ive found ever helped me.

Many thanks for any tips, links and ideas.

Answer 1

You'll want to look for packages that work on Streams and from there it's just about piping your streams to output as necessary. Using Express or just the built-in HTTP you can accomplish this quite easily. Here's an example built around osx-audio which provides a PCM stream, lame which can encode a stream to mp3, and Express:

var Webcast = function(options) {

  var lame = require('lame');
  var audio = require('osx-audio');
  var fs = require('fs');

  // create the Encoder instance
  var encoder = new lame.Encoder({
    // input
    channels: 2,        // 2 channels (left and right)
    bitDepth: 16,       // 16-bit samples
    sampleRate: 44100,  // 44,100 Hz sample rate

    // output
    bitRate: options.bitrate,
    outSampleRate: options.samplerate,
    mode: (options.mono ? lame.MONO : lame.STEREO) // STEREO (default), JOINTSTEREO, DUALCHANNEL or MONO
  });

  var input = new audio.Input();
  input.pipe(encoder);

  // set up an express app
  var express = require('express')
  var app = express()

  app.get('/stream.mp3', function (req, res) {
    res.set({
      'Content-Type': 'audio/mpeg3',
      'Transfer-Encoding': 'chunked'
    });
    encoder.pipe(res);
  });

  var server = app.listen(options.port);
}

module.exports = Webcast;

How you get your input stream might be the most interesting part, but that will depend on your implementation. The popular request package is built around Streams as well though, so it might just be an HTTP request away!