Mac FFmpeg编译和解决nasm/yasm not found or too old错误

FFmpeg编译
下载代码：git clone https://git.ffmpeg.org/ffmpeg.git
然后输入命令进行编译：找到下载的目录下，然后用命令进入这个文件夹下cd ffmpeg,然后输入./configure。
竟然没有编译过出现错误是
nasm/yasm not found or too old. Use --disable-x86asm for a crippled build.

If you think configure made a mistake, make sure you are using the latest
version from Git. If the latest version fails, report the problem to the
[e-mail] mailing list or IRC #ffmpeg on irc.freenode.net.
Include the log file “ffbuild/config.log” produced by configure as this will help
solve the problem.

分析：yasm是汇编编译器，ffmpeg为了提高效率使用了汇编指令，如MMX和SSE等。所以系统中未安装yasm时，就会报上面错误。

解决错误：安装yasm编译器。安装方法如下：

1）下载：[yasm的下载链接](http://www.tortall.net/projects/yasm/releases/yasm-1.3.0.tar.gz)

2）解压：把下载下来的压缩包进行解压

3）切换路径： cd yasm-1.3.0

4）执行配置： ./configure

5）编译：make

6）安装：make install（提示：Permission denied，就执行sudo make install）

安装成功yasm你可以在进入到ffmpeg的文件夹下，进行./configure
make
make install（提示：Permission denied，就执行sudo make install）
然后打出ffmpeg

ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 7.0.2 (clang-700.1.81)
  configuration: 
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
Use -h to get full help or, even better, run 'man ffmpeg'

这样ffmpeg就安装成功了。

ffplay: command not found
如果你要用到ffplay的时候，发现没有这个命令的时候，是因为ffplay和ffmpeg不是在一起的，需要单独下载。ffplay下载地址 http://evermeet.cx/ffmpeg/ 。把下载下来的文件双击打开运行，如果提示Permission denied，到系统偏好设置，打开安全与隐私，允许ffplay运行就可以了。运行完之后，再在.bash_profile文件配置ffplay path就可以了(这个路径就是ffplay文件的位置)。

./configure --prefix=/usr/local/ffmpeg --enable-gpl --enable-small --arch=x86_64 --enable-nonfree --enable-libfdk-aac --enable-libx264 --enable-filter=delogo --enable-debug --disable-optimizations --enable-shared --enable-libfreetype

##安装libx264
下载地址http://download.videolan.org/pub/videolan/x264/snapshots/
./configure --enable-shared
#make
#make install

libfdk_aac not found

fdk_aac 下载地址https://sourceforge.net/projects/opencore-amr/files/fdk-aac/

1.解压缩
2.  ./configure
3. make
4. make install (sudo make install)