I’ve fixed in this way
sudo -s echo "deb http://www.deb-multimedia.org jessie main non-free" >> /etc/apt/sources.list echo "deb-src http://www.deb-multimedia.org jessie main non-free" >> /etc/apt/sources.list apt-get update apt-get install deb-multimedia-keyring apt-get update apt-get install ffmpeg x264 mplayer exit exit