参考这两篇文章，先配置Mac 下 FFmpeg环境，再编译IOS FFmpeg库
Mac配置FFmpeg： //www.greatytc.com/p/70b0af4d0ec7
编译IOS FFmpeg库： https://blog.csdn.net/To_by/article/details/52151077
过程中遇到的问题：
一，关于MAC系统没有修改usr bin和usr sbin文件夹权限问题
1.重启电脑
2.command + R 进入recover模式
3.点击最上方菜单使用工具，选择终端
4.运行命令csrutil disable
5.当出现successfully字样，代表关闭成功
二，xcode9环境下错误 xcrun -sdk iphoneos clang is unable to create an executable file.
终端执行以下命令：
sudo xcode-select --switch /Applications/Xcode.app
三，mac配置FFmpeg后没有ffplay的解决办法
终端执行以下命令：
brew reinstall ffmpeg --with-sdl2
四，mac FFmpeg集成所需库的方法
brew reinstall ffmpeg --with-sdl2 --with-fdk-aac --with-fontconfig
可以添加多个
==> Options
--with-chromaprint
Enable the Chromaprint audio fingerprinting library
--with-fdk-aac
Enable the Fraunhofer FDK AAC library
--with-fontconfig
Build with fontconfig support
--with-freetype
Build with freetype support
--with-frei0r
Build with frei0r support
--with-game-music-emu
Build with game-music-emu support
--with-libass
Enable ASS/SSA subtitle format
--with-libbluray
Build with libbluray support
--with-libbs2b
Build with libbs2b support
--with-libcaca
Build with libcaca support
--with-libgsm
Build with libgsm support
--with-libmodplug
Build with libmodplug support
--with-librsvg
Enable SVG files as inputs via librsvg
--with-libsoxr
Enable the soxr resample library
--with-libssh
Enable SFTP protocol via libssh
--with-libvidstab
Enable vid.stab support for video stabilization
--with-libvorbis
Build with libvorbis support
--with-libvpx
Build with libvpx support
--with-opencore-amr
Enable Opencore AMR NR/WB audio format
--with-openh264
Enable OpenH264 library
--with-openjpeg
Enable JPEG 2000 image format
--with-openssl
Enable SSL support
--with-opus
Build with opus support
--with-rtmpdump
Enable RTMP protocol
--with-rubberband
Enable rubberband library
--with-sdl2
Enable FFplay media player
--with-snappy
Enable Snappy library
--with-speex
Build with speex support
--with-srt
Enable SRT library
--with-tesseract
Enable the tesseract OCR engine
--with-theora
Build with theora support
--with-tools
Enable additional FFmpeg tools
--with-two-lame
Build with two-lame support
--with-wavpack
Build with wavpack support
--with-webp
Enable using libwebp to encode WEBP images
--with-x265
Enable x265 encoder
--with-xz
Enable decoding of LZMA-compressed TIFF files
--with-zeromq
Enable using libzeromq to receive commands sent through a libzeromq client
--with-zimg
Enable z.lib zimg library
--without-gpl
Disable building GPL licensed parts of FFmpeg
--without-lame
Disable MP3 encoder
--without-qtkit
Disable deprecated QuickTime framework
--without-securetransport
Disable use of SecureTransport
--without-x264
Disable H.264 encoder
--without-xvid
Disable Xvid MPEG-4 video encoder
