homebrew已经支持，建议直接 brew install ffmpeg 。以下方式会缺少一些库且较为麻烦～

参见此项目：https://github.com/ssut/ffmpeg-on-apple-silicon
前提是已经安装homebrew，网上有很多教程，不再赘述。

git clone https://github.com/ssut/ffmpeg-on-apple-silicon.git
cd ffmpeg-on-apple-silicon

然后运行

./build.bash

等待编译。

cd workdir/compile/ffmpeg
sudo make install

ffmpeg 

输出

ffmpeg version git-2021-09-09-0b4d009 Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple clang version 12.0.5 (clang-1205.0.22.11)
  configuration:
  libavutil      57.  5.100 / 57.  5.100
  libavcodec     59.  7.103 / 59.  7.103
  libavformat    59.  5.100 / 59.  5.100
  libavdevice    59.  0.101 / 59.  0.101
  libavfilter     8.  7.101 /  8.  7.101
  libswscale      6.  1.100 /  6.  1.100
  libswresample   4.  0.100 /  4.  0.100
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'