No YouTube Volume Normalization.user.js

// ==UserScript==
// @name         No YouTube Volume Normalization
// @namespace    https://gist.github.com/abec2304
// @match        https://www.youtube.com/*
// @grant        GM_addElement
// @version      2.72
// @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 + "' }";
        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 associated volume panel");
            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));

Hi, I have a problem with this script, I've developed my own slider that sets the document.querySelector('video').playbackRate from 0.05x-3.00x, the problem is that the range 2.00x-3.00x resets this normalization script which in turn noticeably reloads the video player as it flickers then:

ytvolfix2: observed a video element being added
ytvolfix2: updating style
ytvolfix2: shadowed volume property
ytvolfix2: initial volume set

Those 4 lines are spammed whenever I'm moving in that range and I can notice that the color of the background of the volume slider is being changed gradually to stronger purple shade whenever this happens. Any guess? I'm using latest Librewolf on Linux with only this script, uBlock Origin and I'm just only trying to modify document.querySelector('video').playbackRate beyond 2.00x. I haven't looked at your code just yet, I thought about asking about clues first.

The volume bar turning more purple is part of my script, I added that as a visual indicator that unexpected behavior is occurring.

I tried adjusting playbackRate beyond 2x with LibreWolf on Windows and wasn't able to reproduce your issue.

Perhaps LibreWolf on Linux doesn't properly support higher playback rates and causes the video element to be re-initialized.

It kind of fixed itself throughout the week... and I'm not sure what caused this. Probably youtube changed something. Anyway, really thank you for this script. It is an absolute must-have on any firefox based browser when using Linux's audio stack such as pulseaudio or pipewire due to weird bugs, because reported volume levels to system are all out of wack, but you probably know this already.

Can you add support for YT Music?