JAVASCRIPT media.codecs.js

log("loading media.codec.js");
/**
 * Input might look funky, we need to normalize it so e.g. whitespace isn't an issue for our spoofing.
 *
 * @example
 * video/webm; codecs="vp8, vorbis"
 * video/mp4; codecs="avc1.42E01E"
 * audio/x-m4a;
 * audio/ogg; codecs="vorbis"
 * @param {String} arg
 */
const parseInput = (arg) => {
  const [mime, codecStr] = arg.trim().split(";");
  let codecs = [];
  if (codecStr && codecStr.includes("codecs=\"")) {
    codecs = codecStr.trim().
      replace(`codecs="`, "").
      replace(`"`, "").
      trim().
      split(",").
      filter((x) => !!x).
      map((x) => x.trim());
  }
  return {
    mime,
    codecStr,
    codecs
  };
};

const canPlayType = {
  // Intercept certain requests
  apply: function(target, ctx, args) {
    if (!args || !args.length) {
      return target.apply(ctx, args);
    }
    const { mime, codecs } = parseInput(args[0]);
    // This specific mp4 codec is missing in Chromium
    if (mime === "video/mp4") {
      if (codecs.includes("avc1.42E01E")) {
        return "probably";
      }
    }
    // This mimetype is only supported if no codecs are specified
    if (mime === "audio/x-m4a" && !codecs.length) {
      return "maybe";
    }

    // This mimetype is only supported if no codecs are specified
    if (mime === "audio/aac" && !codecs.length) {
      return "probably";
    }
    // Everything else as usual
    return target.apply(ctx, args);
  }
};

/* global HTMLMediaElement */
utils.replaceWithProxy(HTMLMediaElement.prototype, "canPlayType", canPlayType);