编译：
http://www.jianshu.com/p/147c03553e63
http://www.cocoachina.com/ios/20150514/11827.html
http://cnbin.github.io/blog/2015/05/19/iospei-zhi-ffmpegkuang-jia/
http://blog.sina.com.cn/s/blog_47522f7f0102vbwp.html
使用：
http://www.cnblogs.com/moonvan/p/3244943.html
http://blog.****.net/sing_sing/article/details/8468798
http://www.jianshu.com/p/c33f4c96074e
http://blog.****.net/sukhoi27smk/article/details/18842725
裁剪：
http://www.cnblogs.com/smileEvday/archive/2013/11/21/ffmpeg.html
http://*.com/questions/24849129/compile-ffmpeg-without-most-codecs
详细解构：
http://blog.****.net/leixiaohua1020/article/details/15811977