Disable youtube volume normalization (allow true video 100% volume)

tampermonkey-script.js

// ==UserScript==
// @name         YouTube Disable Normalization
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Allows true 100% volume on youtube videos.
// @author       Wouter Gerarts
// @match        https://www.youtube.com/*
// @match        https://youtube.com/*
// @grant        none
// ==/UserScript==

var alwaysEnable = true;

(function() {
    'use strict';

    function baseElement() {
        return document.querySelector('#content');
    }

    if (typeof fullVolumeButtonTaskId === 'number') {
        console.log('clearing interval');
        clearInterval(fullVolumeButtonTaskId);
    }

    function createFullVolumeButton() {
        var el = document.createElement('button');
        el.innerText = '100% Volume';
        el.classList.add('full-volume-addon-button');
        el.onclick = function() {
            var video = baseElement().querySelector('video');
            video.volume = 1;
        };
        return el;
    }

    function round (num, sig) {
        var mult = Math.pow(10, sig);
        return Math.round(num * mult) / mult;
    }

    var fullVolumeButtonTaskId = setInterval(function() {
        if (baseElement().querySelector('video') === undefined) {
            console.log('video element not found');
            return;
        }
        if (baseElement().querySelector('.full-volume-addon-button') != undefined) {
            console.log('full volume addon button already found');
            clearInterval(fullVolumeButtonTaskId);
            return;
        }
        var volumeSlider = baseElement().querySelector('.ytp-volume-slider-handle')
        if (volumeSlider === undefined || volumeSlider === null) {
            console.log('volumeSlider not found');
            return;
        }
        var video = baseElement().querySelector('video');
        var volumeSliderLeftStr = volumeSlider.style.left;
        var volumeSliderLeft = volumeSliderLeftStr.substr(0, volumeSliderLeftStr.length - 2);
        var volumeSliderValue = parseFloat(volumeSliderLeft) * 2.5;
        console.log('Checking slider ' + round(volumeSliderValue / 100, 2).toString() + ' against value ' + round(video.volume, 2).toString());
        if (alwaysEnable || volumeSliderValue / 100 > video.volume) {
            var videoTitleElement = baseElement().querySelector('.ytd-video-primary-info-renderer');
            videoTitleElement.appendChild(createFullVolumeButton());
        } else {
            console.log('volume slider did not meet criteria for Full Volume button');
        }
    }, 500);
})();

Thanks for sharing that. I created a new blank profile and it works, so my FF profile is just broken which I've seen before.

Any chance of an update? Seems to have just broken for me..

Any chance of an update? Seems to have just broken for me..

I maintain an alternative script which I occasionally update https://gist.github.com/abec2304/2782f4fc47f9d010dfaab00f25e69c8a