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      2.80
// @author       abec2304
// @description  Enjoy YouTube videos at their true volume
// @run-at       document-start
// @allFrames    true
// ==/UserScript==

/* eslint-env browser, greasemonkey */
/* biome-ignore-all lint/style/useTemplate: legacy support */
/* biome-ignore-all lint/complexity/useArrowFunction: legacy support */
/* biome-ignore-all lint/suspicious/noRedundantUseStrict: quirky linters */

(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 offset = "position: absolute; left: 0 !important; transform: translate(-100%)";
    var color = "background: " + volumeColors[styleNum % volumeColors.length] + " !important";
    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::after { " + color + "; " + offset + "; }";
    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;
    }

    if (videoElem.volume === 42) {
      logMessage("shadowed value indicates we already handled this video");
      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) {
      volumePanel = document.querySelector("ytmusic-player-bar #volume-slider #sliderBar");
      if (!volumePanel) {
        logMessage("abandoning shadow - no associated volume panel");
        return;
      } else {
        logMessage("found music subdomain volume panel");
      }
    }

    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) {
        var volumePanel;
        var allVideo;

        var processNext = function (index, videoLen) {
          if (index < videoLen) {
            logMessage("evaluating potential video element");
            handleVideo(allVideo[index]);
            processNext(index + 1, videoLen);
          }
        };

        if ("VIDEO" === node.tagName) {
          logMessage("observed a video element being added");
          handleVideo(node);
        } else {
          volumePanel = node.querySelector ? node.querySelector(".ytp-volume-panel") : null;
          if (volumePanel) {
            logMessage("volume panel lazily added");
          } else {
            return;
          }
          allVideo = document.querySelectorAll("video");
          processNext(0, allVideo.length);
        }
      });
    });
  });

  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);

Yes I'm infact using SmartTube right now. It directly offloads stream files into Android's local Exoplayer/Media3. Hence no need of loudness normalisation at all.

But I can't seem to use YouTube Music with it. TizenTube on the other hand, is exactly the same as YouTube supporting YTMusic too. But it lacks the original volume boost and instead lowers to -14 LUFS target.