Force audio to play in one ear
// ==UserScript==
// @name One-Ear Audio
// @namespace 0x539.BiStereo
// @version 0.1.1
// @description Force audio to play in one ear
// @author The0x539
// @match *://*.twitch.tv/*
// @match *://*.youtube.com/*
// @grant GM.registerMenuCommand
// @grant GM.unregisterMenuCommand
// @license AGPL-3.0
// ==/UserScript==
'use strict';
class Reroute {
constructor(element) {
this.element = element;
this.ctx = new AudioContext();
this.source = this.ctx.createMediaElementSource(this.element);
this.split = this.ctx.createChannelSplitter(2);
this.merge = this.ctx.createChannelMerger(2);
this.source.connect(this.split);
this.setSide(null);
this.merge.connect(this.ctx.destination);
}
setSide(side) {
this.split.disconnect();
this.split.connect(this.merge, 0, side ?? 0);
this.split.connect(this.merge, 1, side ?? 1);
}
}
const reroutes = new Map();
const getReroute = (element) => {
if (!reroutes.has(element)) {
reroutes.set(element, new Reroute(element));
}
return reroutes.get(element);
}
let setupDone = false;
let currentSide = null;
function applyToPage(side) {
currentSide = side;
if (setupDone) {
for (const reroute of reroutes.values()) {
reroute.setSide(currentSide);
}
return;
} else {
setupDone = true;
}
const rerouteAll = () => {
for (const element of document.querySelectorAll('video')) {
getReroute(element).setSide(currentSide);
}
};
rerouteAll();
// TODO: a way to deactivate the full page override, disconnecting this observer
const observer = new MutationObserver((mutations) => {
mutations.forEach((mutation) => {
if (mutation.type === 'childList' && mutation.addedNodes.length > 0) {
rerouteAll();
}
});
});
observer.observe(document.body, { childList: true, subtree: true });
}
GM.registerMenuCommand('Page -> Left', () => applyToPage(0));
GM.registerMenuCommand('Page -> Stereo', () => applyToPage(null));
GM.registerMenuCommand('Page -> Right', () => applyToPage(1));