fs.createReadStream('b.mp3') reduce latency

Question

I'm playing around with events triggering sounds (500 msec long), therefore I use the lame library.

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

while(listening) {
    if(eventIsFired) {
        fs.createReadStream('b.mp3')
            .pipe(new lame.Decoder)
            .pipe(new Speaker);
    }
}

Is there any way to preload the stream/file, so I won't need to load it on every single event? it actually blocks my whole while loop and making it async didn't work. How can I reduce latency and make it more efficient?

Answer 1

You can cache the mp3 file to a buffer, then convert that buffer to a readable stream when you need.

var lame = require('lame');
var fs = require('fs');
var Speaker = require('speaker');
var Readable = require('stream').Readable;

var mp3Buffer = fs.readFileSync('b.mp3');

while(listening) {
    if(eventIsFired) {
        bufferToReadableStream(mp3Buffer)
            .pipe(new lame.Decoder)
            .pipe(new Speaker);
    }
}

function bufferToReadableStream(buffer) {
    let stream = new Readable();
    stream.push(buffer);
    stream.push(null);
    return stream;
}