Someone

ffmpeg -y -f alsa -ac 2 -i pulse -f x11grab -r 30 -s `xdpyinfo | grep 'dimensions:'|awk '{print $2}'` -i :0.0 -acodec pcm_s16le output.wav -an -vcodec libx264 -vpre lossless_ultrafast -threads 0 output.mp4

ffmpeg -f x11grab -s wxga -r 25 -i :0.0 -sameq /tmp/out.mpg

ffmpeg -f x11grab -r 25 -s 800x600 -i :0.0 /tmp/outputFile.mpg

ffmpeg -f x11grab -s `xdpyinfo | grep 'dimensions:'|awk '{print $2}'` -r 25 -i :0.0 -sameq /tmp/out.mpg > /root/howto/capture_screen_video_ffmpeg