// ==UserScript==
// @name YouTube H.264 (h264ify) 
// @name:ru YouTube H.264 (h264ify)
// @namespace https://www.youtube.com
// @version 18112023.2
// @description https://github.com/erkserkserks/h264ify
// @description:ru https://github.com/erkserkserks/h264ify
// @match *://*.youtube.com/*
// @match *://*.youtube-nocookie.com/*
// @match *://*.youtubekids.com/*
// @license MIT
// @grant none
// @run-at document-start
// @downloadURL none
// ==/UserScript==

const block60fps = true;

function modifyVideoTypeChecker() {
  const videoElement = document.createElement('video');
  const originalCanPlayType = videoElement.canPlayType.bind(videoElement);
  Object.setPrototypeOf(videoElement, {
    canPlayType: makeModifiedTypeChecker(originalCanPlayType)
  });

  const mediaSource = window.MediaSource;

  if (mediaSource === undefined) return;
  const originalIsTypeSupported = mediaSource.isTypeSupported.bind(mediaSource);
  mediaSource.isTypeSupported = makeModifiedTypeChecker(originalIsTypeSupported);
}

const makeModifiedTypeChecker = (originalChecker) => (type) => {
  if (typeof type !== 'string') return '';
  const disallowedTypes = ['webm', 'vp8', 'vp9', 'av01'];

  for (const disallowedType of disallowedTypes) {
    if (type.includes(disallowedType)) return '';
  }

  if (block60fps) {
    const match = /framerate=(\d+)/.exec(type);
    if (match && match[1] > 30) return '';
  }

  return typeof originalChecker === 'function' ? originalChecker(type) : '';
};

modifyVideoTypeChecker();