docs: private static int moveToAPP1EXIF(InputStream is) throws IOException {
      if (moveToMarker(is, MARKER_APP1)) {
        // read block length
        // subtract 2 as length contain SIZE field we just read
        int length = StreamProcessor.readPackedInt(is, 2, false) - 2;
        if (length > 6) {
          int magic = StreamProcessor.readPackedInt(is, 4, false);
          length -= 4;
          int zero = StreamProcessor.readPackedInt(is, 2, false);
          length -= 2;
          if (magic == APP1_EXIF_MAGIC && zero == 0) {
            // JEITA CP-3451 Exif Version 2.2
            return length;
          }
        }
      }
      return 0;
    }