Compiled with rtools-backports with dependencies from rtools-packages.
Example linking flags:
-lavfilter -lswscale -lpostproc -lavformat -lavcodec -lswresample -lavutil \
-lvorbis -lvorbisenc -logg -lvpx \
-lbz2 -lsecur32 -lws2_32 -liconv -lz -lmp3lame -lx264 \
-lxvidcore -lole32 -lm -luser32 -lbcrypt