1# https://developers.google.com/speed/webp/docs/riff_container 2 3# FourCC 4"ALPH" 5"ANIM" 6"ANMF" 7"EXIF" 8"ICCP" 9"RIFF" 10"VP8 " 11"VP8L" 12"VP8X" 13"WEBP" 14"XMP " 15 16# VP8 signature 17"\x9D\x01\x2A" 18