I have programmed a server that creates an audio stream from my MacBook's audio input, using express, osx-audio and lame:
const http = require("http");
const express = require("express");
const audio = require("osx-audio");
const lame = require("lame");
const audioInput = new audio.Input();
const encoder = new lame.Encoder({
channels: 2,
bitDepth: 16,
sampleRate: 44100,
bitRate: 128,
outSampleRate: 22050,
mode: lame.STEREO
});
audioInput.pipe(encoder);
const app = express();
const server = http.Server(app);
app.get("/stream.mp3", (req, res) => {
res.set({
"Content-Type": "audio/mpeg",
"Transfer-Encoding": "chunked"
});
encoder.pipe(res);
});
server.listen(3000);
On the client side, the sound from this audio stream is included as an <audio> element like so:
<audio controls autoplay preload="none">
<source src="./stream.mp3" type="audio/mpeg" />
<p>Oops – your browser doesn't support HTML5 audio!</p>
</audio>
This works – I can hear the sound from the input source I've selected on my laptop from any browser that is connected to the server when I click the “play” button on the audio element.
However the audio played by the browser lags several seconds behind the original signal. It seems although I'm using preload="none", the browser buffers quite a lot of the audio stream before it starts playing it.
Is there something obvious missing here? Is there a better way to achieve real-time audio with only a few milliseconds latency instead of several seconds?
If you're interested, my project's complete source code is here on GitHub.
