$ git clone https://github.com/opencv/opencv.git
$ git clone https://github.com/mltframework/mlt.git
$ mkdir opencv/build
$ cd opencv/build
$ cmake .. -DOPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules

--     FFMPEG:                      NO
--       avcodec:                   NO
--       avformat:                  NO
--       avutil:                    NO
--       swscale:                   NO
--       avresample:                NO