public static boolean isExtendedWebpHeaderWithAlpha(
      final byte[] imageHeaderBytes, final int offset) {
    boolean isVp8x = matchBytePattern(imageHeaderBytes, offset + 12, WEBP_VP8X_BYTES);
    // Has ALPHA is 5th bit (00010000 == 16) on 21st byte (imageHeaderBytes[20])
    boolean hasAlphaBit = (imageHeaderBytes[offset + 20] & 16) == 16;
    return isVp8x && hasAlphaBit;
  }
Checks whether underlying platform supports extended WebPs
fbcore/src/main/java/com/facebook/common/webp/WebpSupportStatus.java