compile ffmepg with amr

• 下载ffmpeg

http://ffmpeg.org/releases/ffmpeg-0.11.5.tar.gz

• 下载opencore-amr

https://sourceforge.net/projects/opencore-amr/files/opencore-amr/opencore-amr-0.1.3.tar.gz

参考：

https://blog.csdn.net/weixin_30763455/article/details/97807948