准备文件：
    ffmpeg源码
    https://www.ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2
    x264
    git clone git://git.videolan.org/x264.git
    yasm
    http://www.tortall.net/projects/yasm/releases/yasm-1.3.0.tar.gz

    编译安装过程：
    1、安装yasm 

    1. tar zxvf yasm-1.3.0.tar.gz 
    2. cd yasm-1.3.0
    3.  ./configure 
    4.  make
    5.  make install
    6.  yasm --version

    2、编译安装x264

    1. cd x264 
    2. ./configure --enable-shared --enable-pthread --enable-pic
    3. make
    4. make install

    3、编译ffmpeg

    1. 1. cd ffmpeg
    2. 2. ./configure --enable-libx264 --enable-gpl --enable-shared  --extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib --enable-pic
    3. 3. make
    4. 4. make install
    5. 5.

    安装好ffmpeg运行时如果提示

    1. ffmpeg: error while loading shared libraries: libavdevice.so.52: cannot open shared object file: No such file or directory

    则需要修改文件：/etc/ld.so.conf
    在文件尾添加一行：
    /usr/local/lib
    然后执行命令：
    ldconfig

    重新运行ffmpeg -encoders | grep x264会发现安装成功