No YouTube Volume Normalization.user.js

// ==UserScript==
// @name         No YouTube Volume Normalization
// @namespace    https://gist.github.com/abec2304
// @match        https://www.youtube.com/*
// @match        https://music.youtube.com/*
// @grant        GM_addElement
// @version      2.73beta
// @author       abec2304
// @description  Enjoy YouTube videos at their true volume
// @run-at       document-start
// @allFrames    true
// ==/UserScript==

/* eslint-env browser, greasemonkey */

(function xvolnorm(pageScript, thisObj) {
    "use strict";

    var scriptId = "ytvolfix2";

    var logMessage = function(message) {
        console.debug(scriptId + "_injector: " + message);
    };

    var digestMessage = function(message, callback) {
        var msgBytes = new TextEncoder().encode(message);
        logMessage("attempting to hash script");
        window.crypto.subtle.digest("SHA-256", msgBytes).then(function(buffer) {
            var arr;
            var hex;

            if(typeof cloneInto !== typeof undefined) {
                // workaround for Firemonkey
                buffer = cloneInto(buffer, thisObj);
            }

            try {
                arr = Array.from(new Uint8Array(buffer));
                hex = arr.map(function(b) {
                    return b.toString(16).padStart(2, "0");
                }).join("");
                logMessage("obtained hash");
                callback(hex);
            } catch(_ignore) {
                logMessage("unable to convert hash data");
                callback("unknown");
            }
        });
    };

    var inject = function(hash) {
        var content = "(" + pageScript + ")('" + scriptId + "', '" + hash + "');";
        logMessage("preparing page script");
        if(document.head) {
            GM_addElement("script", {id: scriptId, textContent: content});
            logMessage("injected page script");
            return;
        }
        document.addEventListener("DOMContentLoaded", function() {
            GM_addElement("script", {id: scriptId, textContent: content});
            logMessage("injected page script (delayed)");
        });
    };

    if(typeof GM_addElement === typeof undefined) {
        window.GM_addElement = function(a, b) {
            var elem = document.createElement(a);
            Object.keys(b).forEach(function(key) {
                elem[key] = b[key];
            });
            document.head.appendChild(elem);
            return elem;
        };
        logMessage("defined addElement polyfill");
    }

    try {
        digestMessage(pageScript, inject);
    } catch(_ignore) {
        logMessage("unable to hash");
        inject("unknown");
    }
}(function(scriptId, hash) {
    "use strict";

    var logMessage = function(message) {
        console.debug(scriptId + ": " + message);
    };

    var _ignore = logMessage("page script called");

    var volumeColors = [
        "thistle",
        "plum",
        "orchid",
        "mediumorchid",
        "darkorchid",
        "darkviolet"
    ];

    var styleNum = 0;

    var addVolumeStyle = function(parent) {
        var color = volumeColors[styleNum % volumeColors.length];
        var about = "No YouTube Volume Normalization #" + hash.slice(0, 16);

        var curStyle = parent.querySelector("style." + scriptId + "_style");
        if(curStyle) {
            logMessage("updating style");
        } else {
            curStyle = document.createElement("style");
            curStyle.className = scriptId + "_style";
            parent.appendChild(curStyle);
            logMessage("added style element");
        }
        curStyle.textContent = ".ytp-volume-slider-handle::before { background: " + color + "; z-index: -1; }";
        curStyle.textContent += " .ytp-sfn-content::after { content: '" + about + "' }";
        curStyle.textContent += " ytmusic-nerd-stats::after { content: '" + about + "' }";
        styleNum += 1;
    };

    var setVolume = function(panel, video, setter) {
        var newVolume = panel.getAttribute("aria-valuenow") / 100;
        if(newVolume === video.lastVolume) {
            return;
        }
        video.lastVolume = newVolume;
        setter.call(video, newVolume);
    };

    var handleVideo = function(videoElem) {
        var parentL0;
        var parentL1;
        var desc;
        var setter;
        var volumePanel;

        parentL0 = videoElem.parentNode;
        if(!parentL0) {
            logMessage("video immediately detached from page " + videoElem.outerHTML);
            return;
        }

        parentL1 = parentL0.parentNode;
        if(!parentL1) {
            logMessage("video detached from page " + videoElem.outerHTML);
            return;
        }

        desc = Object.getOwnPropertyDescriptor(HTMLMediaElement.prototype, "volume");
        if(!desc) {
          logMessage("using archaic volume descriptor");
          desc = Object.getOwnPropertyDescriptor(videoElem, "volume");
        }

        setter = desc.set;

        volumePanel = parentL1.querySelector(".ytp-volume-panel");
        if(!volumePanel) {
            logMessage("no regular associated volume panel");
            volumePanel = document.querySelector("ytmusic-player-bar #volume-slider #sliderBar")
            if(!volumePanel) {
                logMessage("no associated music volume panel either");
                return;
            }
        }

        addVolumeStyle(parentL1);

        Object.defineProperty(videoElem, "volume", {
            get: function() {
                logMessage("read of shadowed volume value");
                return 42;
            },
            set: function(_ignore) {
                var toCall = function() {
                    setVolume(volumePanel, videoElem, setter);
                };
                // slight delay to allow volume panel to update
                window.setTimeout(toCall, 5);
            }
        });
        logMessage("shadowed volume property");

        setVolume(volumePanel, videoElem, setter);
        logMessage("initial volume set");
    };

    var videoObserver;
    var intervalId;

    var existingVideos = document.querySelectorAll("video");
    logMessage("number of existing video elements = " + existingVideos.length);
    Array.prototype.forEach.call(existingVideos, handleVideo);

    videoObserver = new MutationObserver(function(records) {
        records.forEach(function(mutation) {
            Array.prototype.forEach.call(mutation.addedNodes, function(node) {
                if("VIDEO" === node.tagName) {
                    logMessage("observed a video element being added");
                    handleVideo(node);
                }
            });
        });
    });

    videoObserver.observe(document.documentElement, {childList: true, subtree: true});

    intervalId = window.setInterval(function ytvolfix2cleanup() {
        var scriptElem = document.getElementById(scriptId);
        if(!scriptElem) {
            logMessage("nothing found to clean up");
        } else {
            scriptElem.parentNode.removeChild(scriptElem);
            logMessage("cleaned up own script element");
        }
        clearInterval(intervalId);
    }, 1500);
}, this));

The new UI is terrible, but until this script is updated, YTM works, and I have no issues with ads with my UBlockPlus setup. I majorly use this for music, so.