I'm reading this article
My goal is to play two sounds at the same time. One sound is in a different volume. Having regular "audio" tags is not a solution because it's not working well on mobile devices. So I started to dive into Web Audio API.
I wrote the code below, that works well across all devices. The single issue - I can't figure out how to control the volume. Code from example is not working(
Please help 🙏
function init() {
// Fix up prefixing
window.AudioContext = window.AudioContext || window.webkitAudioContext;
context = new AudioContext();
bufferLoader = new BufferLoader(
context,
[
'mp3/speech.mp3',
'mp3/bg-melody.mp3',
],
finishedLoading
);
bufferLoader.load();
}
function finishedLoading(bufferList) {
document.querySelector('.message').innerHTML = "Ready to play"
// Create two sources and play them both together.
source1 = context.createBufferSource();
source2 = context.createBufferSource();
source1.buffer = bufferList[0];
source2.buffer = bufferList[1];
source1.connect(context.destination);
// This code is not working
var gainNode = context.createGain();
gainNode.gain.value = 0.1;
source2.connect(gainNode);
source2.connect(context.destination);
source2.loop = true;
}
Update:
This change fixed the issue
source2.connect(gainNode).connect(context.destination);
The connect() method returns an AudioNode, which must then have connect() called on it so the Nodes are chained together:
const gainNode = context.createGain()
source2
.connect(gainNode)
.connect(context.destination)
const $ = document.querySelector.bind(document)
const $$ = document.querySelectorAll.bind(document)
const audioCtx = new (AudioContext || webkitAudioContext)()
const gainNodes = [
audioCtx.createGain(),
audioCtx.createGain(),
]
const url = 'https://opus-bitrates.anthum.com/audio/music-96.opus'
loadAudio(url, gainNodes[0])
loadAudio(url, gainNodes[1],
15.132 / (32 * 2), // 32 beats in 15.132s
)
$$('input').forEach((el, i) => {
gainNodes[i].gain.value = el.value / 100
el.oninput = () => gainNodes[i].gain.value = el.value / 100
})
$('#play').onclick = play
$('#pause').onclick = pause
async function loadAudio(url, gainNode, delayS = 0) {
const buffer = await (await fetch(url)).arrayBuffer()
const source = audioCtx.createBufferSource()
source.buffer = await audioCtx.decodeAudioData(buffer)
source.loop = true
source
.connect(gainNode)
.connect(audioCtx.destination)
source.start(delayS)
}
function play() { audioCtx.resume() }
function pause() { audioCtx.suspend() }<button id="play">Play</button><button id="pause">Pause</button><br />
<label><input type="range" value="50" max="100" /> Track 1</label><br />
<label><input type="range" value="50" max="100" /> Track 2</label>