☰

Youtube Loudness Correction

Amplifies any youtube video with loudness lower than 0dB

  1. // ==UserScript==
  2. // @name           Youtube Loudness Correction
  3. // @description    Amplifies any youtube video with loudness lower than 0dB
  4. // @namespace      Septolum
  5. // @include        https://www.youtube.com/*
  6. // @include        https://m.youtube.com/*
  7. // @icon           https://www.youtube.com/favicon.ico
  8. // @version        1.2
  9. // @grant          none
  10. // @run-at         idle
  11. // ==/UserScript==
  12.  
  13. // I created this script because Youtube does not amplify quiet videos, it only quietens loud ones
  14.  
  15. // from: https://stackoverflow.com/a/18997637
  16. setInterval(function () {
  17.   if (this.lastHrefStr !== location.href || this.lastHrefStr === null) {
  18.     this.lastHrefStr = location.href;
  19.     console.log("page change");
  20.     gmMain();
  21.   }
  22. }, 111);
  23.  
  24. function gmMain() {
  25.   "use strict";
  26.  
  27.   var req = new XMLHttpRequest();
  28.   req.open(
  29.     "GET",
  30.     "https://" +
  31.       window.location.host +
  32.       "/watch?v=" +
  33.       /v=(.+?)(?:(?:&.*?)|$)/.exec(window.location.href)[1],
  34.     false
  35.   );
  36.   req.send(null);
  37.   if (req.status == 200) {
  38.     var loudness = parseFloat(
  39.       /"loudnessDb":([-0-9.]+),/.exec(req.responseText)[1]
  40.     );
  41.   }
  42.  
  43.   if (loudness < 0) {
  44.     console.log("Loudness Corrected");
  45.     loudness = 10 ** ((loudness * -1) / 20);
  46.     // from https://stackoverflow.com/questions/43794356/html5-volume-increase-past-100#comment99251398_43794379
  47.     if (window["_gainNode"]) {
  48.       window["_gainNode"].gain.value = loudness;
  49.       return;
  50.     }
  51.     var v = document.querySelector("video");
  52.     var audioCtx = new AudioContext();
  53.     var source = audioCtx.createMediaElementSource(v);
  54.     var gainNode = audioCtx.createGain();
  55.     gainNode.gain.value = loudness;
  56.     source.connect(gainNode);
  57.     gainNode.connect(audioCtx.destination);
  58.     window["_gainNode"] = gainNode;
  59.   } else {
  60.     if (window["_gainNode"]) {
  61.       console.log("Loudness Reset");
  62.       window["_gainNode"].gain.value = 1;
  63.       return;
  64.     }
  65.   }
  66. }