build ffmpeg: ./configure --enable-shared ./configure --enable-gpl --enable-libx264
build opencv: http://answers.opencv.org/question/40425/opencv-build-fails-because-i-cannot-download-icv-on-our-build-farm/ http://www.linuxfromscratch.org/blfs/view/svn/general/opencv.html
/** @brief VideoWriter constructors
The constructors/functions initialize video writers. On Linux FFMPEG is used to write videos; on Windows FFMPEG or VFW is used; on MacOSX QTKit is used. */