From 9230d4f43693c1ab29e12dec0d0d0f4adc12ba38 Mon Sep 17 00:00:00 2001
From: wuggy <ownedbywuigi@gmail.com>
Date: Tue, 15 Sep 2026 14:15:53 -0700
Subject: [PATCH] Add YouTube codec check and their settings

---
 .../preferences/in-content/content.xul        | 20 +++++
 .../youtube-codec-check.user.js               | 77 +++++++++++++++++++
 .../components/internaluserscripts.js         | 48 ++++++++++++
 .../preferences/internaluserscripts.js        |  3 +
 browser/internaluserscripts/moz.build         |  1 +
 .../chrome/browser/preferences/content.dtd    |  8 ++
 6 files changed, 157 insertions(+)
 create mode 100644 browser/internaluserscripts/bundled-scripts/youtube-codec-check.user.js

diff --git a/browser/components/preferences/in-content/content.xul b/browser/components/preferences/in-content/content.xul
index 0cfdc424bf..07f9de0409 100644
--- a/browser/components/preferences/in-content/content.xul
+++ b/browser/components/preferences/in-content/content.xul
@@ -68,8 +68,28 @@
     </rows>
   </grid>
 </groupbox>
+
 #endif
 
+<!-- YouTube video codecs -->
+<groupbox id="videoGroup" data-category="paneContent" hidden="true">
+  <caption><label>&videoContent.label;</label></caption>
+  <vbox>
+    <checkbox id="youtubeHideUnaccelerated"
+              preference="browser.video.youtube.hide-unaccelerated"
+              label="&youtubeHideUnaccelerated.label;"
+              accesskey="&youtubeHideUnaccelerated.accesskey;" />
+    <checkbox id="youtubeForceH264"
+              preference="browser.video.youtube.force-h264"
+              label="&youtubeForceH264.label;"
+              accesskey="&youtubeForceH264.accesskey;" />
+    <checkbox id="youtubeDisable60fps"
+              preference="browser.video.youtube.disable-60fps"
+              label="&youtubeDisable60fps.label;"
+              accesskey="&youtubeDisable60fps.accesskey;" />
+  </vbox>
+</groupbox>
+
 <groupbox id="notificationsGroup" data-category="paneContent" hidden="true">
   <caption><label>&notificationsPolicy.label;</label></caption>
   <grid>
diff --git a/browser/internaluserscripts/bundled-scripts/youtube-codec-check.user.js b/browser/internaluserscripts/bundled-scripts/youtube-codec-check.user.js
new file mode 100644
index 0000000000..c6d6165c88
--- /dev/null
+++ b/browser/internaluserscripts/bundled-scripts/youtube-codec-check.user.js
@@ -0,0 +1,77 @@
+/*
+ * Adapted from enhanced-h264ify's inject_codec_check.js.
+ *
+ * The MIT License (MIT)
+ * Copyright (c) 2019 alextrv
+ * Copyright (c) 2015 erkserkserks
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ */
+
+/* YouTube-only codec selection controls. */
+(function () {
+  "use strict";
+
+  var settings = window.__dactyloidaeYouTubeVideoSettings || {};
+  var originalCanPlayType = HTMLMediaElement.prototype.canPlayType;
+  var originalIsTypeSupported = window.MediaSource &&
+                                window.MediaSource.isTypeSupported;
+
+  function isVideoType(type) {
+    return /(^|\s|;)video\//i.test(type) ||
+           /(^|[; ])codecs\s*=\s*["']?(?:avc|vp0|av0)/i.test(type);
+  }
+
+  function isBlocked(type) {
+    if (!type || !isVideoType(type)) {
+      return false;
+    }
+
+    // AV1 is always blocked, independently of the preferences.
+    if (/av01|av99/i.test(type)) {
+      return true;
+    }
+
+    if (settings.forceH264 && !/avc1|avc3/i.test(type)) {
+      return true;
+    }
+
+    if (settings.hideUnaccelerated &&
+        !settings.vp9HardwareAccelerated && /vp9|vp09/i.test(type)) {
+      return true;
+    }
+
+    if (settings.disable60fps) {
+      var match = /(?:framerate|fps)\s*=\s*([0-9]+(?:\.[0-9]+)?)/i.exec(type);
+      if (match && Number(match[1]) > 30) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  HTMLMediaElement.prototype.canPlayType = function (type) {
+    if (isBlocked(type)) {
+      return "";
+    }
+    return originalCanPlayType.call(this, type);
+  };
+
+  if (window.MediaSource && originalIsTypeSupported) {
+    window.MediaSource.isTypeSupported = function (type) {
+      if (isBlocked(type)) {
+        return false;
+      }
+      return originalIsTypeSupported.call(this, type);
+    };
+  }
+}());
diff --git a/browser/internaluserscripts/components/internaluserscripts.js b/browser/internaluserscripts/components/internaluserscripts.js
index d60ce90ea9..8876acaac7 100644
--- a/browser/internaluserscripts/components/internaluserscripts.js
+++ b/browser/internaluserscripts/components/internaluserscripts.js
@@ -99,6 +99,54 @@ InternalUserscriptsService.prototype = {
       }
     } catch (e) {}
     let contentWin = win.wrappedJSObject || win;
+    let documentURI = null;
+    try {
+      documentURI = win.document.documentURIObject;
+    } catch (e) {}
+
+    // The codec shim is deliberately limited to YouTube.  Use the browser's
+    // decoder probe rather than guessing from the user's graphics settings.
+    if (documentURI &&
+        documentURI.host &&
+        /(^|\.)youtube(?:-nocookie)?\.com$/i.test(documentURI.host)) {
+      let settings = {
+        hideUnaccelerated: Services.prefs.getBoolPref(
+          "browser.video.youtube.hide-unaccelerated", true),
+        forceH264: Services.prefs.getBoolPref(
+          "browser.video.youtube.force-h264", false),
+        disable60fps: Services.prefs.getBoolPref(
+          "browser.video.youtube.disable-60fps", false),
+        vp9HardwareAccelerated: false,
+      };
+
+      let loadCodecShim = function (vp9HardwareAccelerated) {
+        settings.vp9HardwareAccelerated = vp9HardwareAccelerated;
+        contentWin.__dactyloidaeYouTubeVideoSettings = settings;
+        try {
+          Services.scriptloader.loadSubScript(
+            "chrome://internaluserscripts/content/bundled-scripts/youtube-codec-check.user.js",
+            contentWin);
+        } catch (e) {}
+      };
+
+      try {
+        let utils = win.QueryInterface(Ci.nsIInterfaceRequestor)
+                       .getInterface(Ci.nsIDOMWindowUtils);
+        let hardwareSupport = utils.supportsHardwareVP9Decoding;
+        if (hardwareSupport && typeof hardwareSupport.then === "function") {
+          hardwareSupport.then(function (result) {
+            loadCodecShim(/^Yes;/.test(result));
+          }, function () {
+            loadCodecShim(false);
+          });
+        } else {
+          loadCodecShim(/^Yes;/.test(hardwareSupport));
+        }
+      } catch (e) {
+        loadCodecShim(false);
+      }
+    }
+
     let logPolyfill = function (name, source) {
       try {
         if (
diff --git a/browser/internaluserscripts/defaults/preferences/internaluserscripts.js b/browser/internaluserscripts/defaults/preferences/internaluserscripts.js
index f87d1d0121..3dbc97c3bf 100644
--- a/browser/internaluserscripts/defaults/preferences/internaluserscripts.js
+++ b/browser/internaluserscripts/defaults/preferences/internaluserscripts.js
@@ -3,3 +3,6 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 pref("browser.internal-userscripts.enabled", true);
+pref("browser.video.youtube.hide-unaccelerated", true);
+pref("browser.video.youtube.force-h264", false);
+pref("browser.video.youtube.disable-60fps", false);
diff --git a/browser/internaluserscripts/moz.build b/browser/internaluserscripts/moz.build
index 40f2b86f9d..208a980047 100644
--- a/browser/internaluserscripts/moz.build
+++ b/browser/internaluserscripts/moz.build
@@ -30,4 +30,5 @@ FINAL_TARGET_FILES['internal-userscripts'] += [
     'bundled-scripts/textencoderstream-polyfill.user.js',
     'bundled-scripts/transformstream-polyfill.user.js',
     'bundled-scripts/webauthn-microsoft-shim.user.js',
+    'bundled-scripts/youtube-codec-check.user.js',
 ]
diff --git a/browser/locales/en-US/chrome/browser/preferences/content.dtd b/browser/locales/en-US/chrome/browser/preferences/content.dtd
index bca4824f5a..85fd1fcf25 100644
--- a/browser/locales/en-US/chrome/browser/preferences/content.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/content.dtd
@@ -52,3 +52,11 @@
 <!ENTITY  javascriptWebrtc.label           "Enable WebRTC">
 <!ENTITY  javascriptWebrtc.accesskey       "R">
 #endif
+
+<!ENTITY  videoContent.label "Video">
+<!ENTITY  youtubeHideUnaccelerated.label "Hide codecs from YouTube that aren't hardware accelerated">
+<!ENTITY  youtubeHideUnaccelerated.accesskey "H">
+<!ENTITY  youtubeForceH264.label "Force H264 on YouTube">
+<!ENTITY  youtubeForceH264.accesskey "F">
+<!ENTITY  youtubeDisable60fps.label "Disable 60fps video on YouTube">
+<!ENTITY  youtubeDisable60fps.accesskey "D">