convert all WEBP to PNG/JPG

nowebp

# nowebp - find and convert WEBP images
#
# Usage: nowebp [DIR]
#
# nowebp searches the directory hierarchy starting from DIR (current
# directory if absent) for images in WEBP format, and converts each
# image it finds to PNG or JPG, depending on whether it is compressed
# losslessly or contains transparent pixels, or neither, respectively.

export LC_ALL=C

find "${1-.}" \
	-type f \( -name '*.webp' -o -name '*.jpg' -o -name '*.png' \) \
	-exec sh -c '
for src; do
	case $(head -c 42 "$src" | tr -c A-Z0-9 x) in
	RIFF????WEBPVP8X??????????????ANIM* | RIFF????WEBPVP8X??????????????ICCP????ANIM)
		printf "%s: animated WEBP not supported\n" "$src" >&2
		continue ;;
	RIFF????WEBPVP8L* | RIFF????WEBPVP8X??????????????ALPH*)
		fmt=png ;;
	RIFF????WEBPVP8*)
		fmt=jpg ;;
	*)
		continue
	esac

	dest=$src.$fmt
	ffmpeg -loglevel error -i "$src" "$dest" &&
		rm -i "$src"
done' sh {} +

# vi: ft=sh