message: ffmpeg: update 4.0 (master)
  ffmpeg 4.0.2
  openh264 1.8.0
diff: -# Binaries branch name: ffmpeg/master_20180220
  -# Binaries were created for OpenCV: 9819ebc0954c2df62943ebbd5936d325e5dc89e1
  -ocv_update(FFMPEG_BINARIES_COMMIT "0a0e88972a7ea97708378d0488a65f83e7cc5e69")
  -ocv_update(FFMPEG_FILE_HASH_BIN32 "b8120c07962d591e2e9071a1bf566fd0")
  -ocv_update(FFMPEG_FILE_HASH_BIN64 "dc9c50e7b05482acc25d6ce0ac61bf1d")
  -ocv_update(FFMPEG_FILE_HASH_CMAKE "3b90f67f4b429e77d3da36698cef700c")
  +# Binaries branch name: ffmpeg/master_20180918
  +# Binaries were created for OpenCV: e628fd7bce2b5d64c36b5bdc55a37c0ae78bc907
  +ocv_update(FFMPEG_BINARIES_COMMIT "c88df798e9dc3d63840f913714563a730245464a")
  +ocv_update(FFMPEG_FILE_HASH_BIN32 "48c95ce37d5aa6b15b3ad116e331ebc1")
  +ocv_update(FFMPEG_FILE_HASH_BIN64 "d33eca57ae1cfd6287b975b98125f7a3")
  +ocv_update(FFMPEG_FILE_HASH_CMAKE "5fd49e1b84e9f402ca155e27c92d2ce9")
  function(download_win_ffmpeg script_var)
  set(${script_var} "" PARENT_SCOPE)
  