根据李老师的解答，安装SDL库后编译安装了好几次，还是没有ffplay;
wget http://libsdl.org/release/SDL-1.2.15.tar.gz
tar zxvf SDL-1.2.15.tar.gz
cd SDL-1.2.15
./configure --prefix=/usr/local
sudo make install
SDL2成功编译出ffplay,解决办法：
wget http://www.libsdl.org/release/SDL2-2.0.18.tar.gz
tar zxvf SDL2-2.0.18.tar.gz
cd SDL2-2.0.18
./configure --prefix=/usr/local
sudo make install
