take snapshot on ffmpeg with rpos (https://github.com/BreeeZe/rpos)
#How to: Install:
*login to your pi via ssh
cd ~
wget https://raw.githubusercontent.com/imonology/snapshot_with_ffmpeg/master/setup_snapshot_with_ffmpeg.sh
sudo chmod +x setup_snapshot_with_ffmpeg.sh
sudo ./setup_snapshot_with_ffmpeg.sh
#enjoy