WWXD is basically Xvid's frame type decision code stuffed into a VapourSynth
plugin.

The output is somewhat different from Scxvid's, because Xvid's decisions are
also affected by data calculated while encoding frames. WWXD may miss more
scene changes than Scxvid. It may also detect some that Scxvid missed.

WWXD is considerably faster than Scxvid, possibly about six times.

There is no log file. Instead, the frames are tagged with the property
"SceneChange" (1 or 0).

The license is the same as Xvid's, i.e. GPL2.

To compile:
gcc -o libwwxd.so -fPIC -shared -O2 -Wall -Wextra -Wno-unused-parameter $(pkg-config --cflags vapoursynth) src/wwxd.c src/detection.c

To use:
core.wwxd.WWXD(clip=src)