Audio streaming from Javascript to node BinaryServer too slow

I'm using Node.JS BinaryServer and WAV.js to stream audio from the client to the node server.

Problem is - it's too slow.

On an average internet connection, a 10 minutes recording has a delay of 3 minutes to upload. Meaning, after the stream.end event was fired, the client still sends more data to the node server. It's a huge overhead.

As you can see in the Node.js code below, I'm using a BinaryServer with an HttpsServer, since I have no chiose (WebRTC is only allowed in HTTPS).

I read on several places that writing binary data to node.js can be speeded up by adding the highWaterMark to fs.createWriteStream, as suggested here, but I'm not using this class, I'm using the wav.FileWriter class.

Node.js server code:

var binaryServer = require('binaryjs').BinaryServer;
var wav = require('wav');
var https = require('https');

var httpsserver = https.createServer(options).listen(9002);
var server = binaryServer({ server: httpsserver });

server.on('connection', function(client) {
    client.on('stream', function (stream, meta) {

        var fileWriter = new wav.FileWriter('/foo.wav', {
            channels: 1,
            sampleRate: meta.SampleRate,
            bitDepth: 16,
            highWaterMark: Math.pow(2, 16)   // this seems useless
        });
        stream.pipe(fileWriter);
    });
});

Javascript client code:

// This streams the sound to the node server:
var sound = convertFloat32ToInt16(e.inputBuffer.getChannelData(0));
window.Stream.write(sound );

function convertFloat32ToInt16(buffer) {
    l = buffer.length;
    buf = new Int16Array(l);
    while (l--) {
        buf[l] = Math.min(1, buffer[l])*0x7FFF;
    }
    return buf.buffer;
}

Does anyone have an idea how to speed things up ?

Is there a way to implement highWaterMark in wav.FileWriter ?

via Koby Douek