// ==UserScript==// @name         YoutubeMonolyse// @namespace    mailto:help.christopherlovell@gmail.com// @version      0.3.1// @description  Create's a button in the settings menu on a youtube video page that disables/enables stereo/mono audio.// @author       Christopher M. Lovell// @include      https://www.youtube.com/watch?v*// @grant        none// @run-at document-end// ==/UserScript==var buttonSrc = '<div id="ytmid-toggle-btn"class="ytp-menuitem" role="menuitem" tabindex="0">' +'    <div class="ytp-menuitem-label">Toggle Mono</div>' +'    <div class="ytp-menuitem-content">' +'        <button class="ytp-button"><span id="ytmid-toggle-span" class="ytp-menu-label-secondary">Stereo</span></button>' +'    </div>' +'</div>';var context = new AudioContext();var videos = document.getElementsByTagName("video");var audioElement;var isMono = false;var btnSettingSvg;var insertBtnParent;var text;window.toggleMono = () => {if(audioElement == null){audioElement = context.createMediaElementSource(videos[0]);}context.destination.channelCount = isMono? 2 : 1;audioElement.connect(context.destination);isMono = !isMono;return isMono;}window.initialiseTMYoutubeMonolyse = () =>{console.log("Initialising -- YoutubeMonolyse by Christopher Lovell")btnSettingSvg = document.querySelector("#movie_player > div.ytp-chrome-bottom > div.ytp-chrome-controls > div.ytp-right-controls > button.ytp-button.ytp-settings-button");// Youtube's setting menu by default has no elements in it, so we open it up then instantly close it using dispatchEvents.btnSettingSvg.dispatchEvent(new MouseEvent('click'));btnSettingSvg.dispatchEvent(new MouseEvent('click'));insertBtnParent = document.querySelector("#ytp-id-18 > div > div");window.initButtons();}window.initButtons = () => {console.log("Initialising Buttons")insertBtnParent.insertAdjacentHTML('beforeend',buttonSrc);var button = document.querySelector("#ytmid-toggle-btn");console.log(button.innerHTML);text = button.querySelector("#ytmid-toggle-span");console.log(text.innerHTML);button.onclick = function(){console.log("Setting audio to mono!");window.toggleMono();text.innerHTML = isMono ? "Mono" : "Stereo";};}window.initialiseTMYoutubeMonolyse();// VERSION HISTORY// 0.1 Initial release// 0.2 Fixed bug with video that don't have an enable annotation options// 0.3 Fixed issue with mono option not showing up on non-hd videos