Live streaming using FFMPEG to web audio api

Question

I am trying to stream audio using node.js + ffmpeg to browsers connected in LAN only using web audio api.

Not using element because it's adding it's own buffer of 8 to 10 secs and I want to get maximum high latency possible (around 1 to 2 sec max).

Audio plays successfully but audio is very choppy and noisy.

Here is my node.js (server side) file:

var ws = require('websocket.io'), 
server = ws.listen(3000);
var child_process = require("child_process");
var i = 0;
server.on('connection', function (socket) 
{

console.log('New client connected');

var ffmpeg = child_process.spawn("ffmpeg",[
    "-re","-i",
    "A.mp3","-f",
    "f32le",
    "pipe:1"                     // Output to STDOUT
    ]);

 ffmpeg.stdout.on('data', function(data)
 {
    var buff = new Buffer(data);
    socket.send(buff.toString('base64'));
 });
});

And here is my HTML:

var audioBuffer = null;
var context = null;
window.addEventListener('load', init, false);
function init() {
    try {
        context = new webkitAudioContext();
    } catch(e) {
        alert('Web Audio API is not supported in this browser');
    }
}

var ws = new WebSocket("ws://localhost:3000/");

ws.onmessage = function(message)
{
    var d1 = base64DecToArr(message.data).buffer;
    var d2 = new DataView(d1);

    var data = new Float32Array(d2.byteLength / Float32Array.BYTES_PER_ELEMENT);
    for (var jj = 0; jj < data.length; ++jj)
    {
        data[jj] = d2.getFloat32(jj * Float32Array.BYTES_PER_ELEMENT, true);
    }

    var audioBuffer = context.createBuffer(2, data.length, 44100);
    audioBuffer.getChannelData(0).set(data);

    var source = context.createBufferSource(); // creates a sound source
    source.buffer = audioBuffer;
    source.connect(context.destination); // connect the source to the context's destination (the speakers)
    source.start(0);
};

Can any one advise what is wrong?

Regards, Nayan

hello nayan, i am using Web audio api , and want to record the sound played through thje web audio api,, my question stackoverflow.com/questions/21234902/… is here, can you help me — Jot Dhaliwal

Nayan Nayan · Accepted Answer · 2014-01-19T10:15:52

I got it working !!

All I had to do is adjust the number of channel.

I've set FFMPEG to output mono audio and it worked like a charm. Here is my new FFMOEG command:

var ffmpeg = child_process.spawn("ffmpeg",[
    "-re","-i",
    "A.mp3",
    "-ac","1","-f",
    "f32le",
    "pipe:1"                     // Output to STDOUT
    ]);

Live streaming using FFMPEG to web audio api

2 Answers