为什么我会收到此警告以及如何解决？本质上，我想每 4 帧将视频转换为与原始视频具有相同分辨率的 jpg。
[jalal@goku vid2]$ ffmpeg -i debate_vid2.mov -r 0.25 images_%08d.jpg
ffmpeg version 2.6.8 Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-4)
configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --enable-libfaac --enable-nonfree --enable-libfdk-aac --enable-nonfree --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample …我应该如何解决这个问题？
Tue Oct 31 21:52:56 mona@dhcp-wifi-8021x-155-41-82-88:~$ brew update && brew upgrade && brew cleanup
Error: /usr/local is not writable. You should change the
ownership and permissions of /usr/local back to your
user account:
sudo chown -R $(whoami) /usr/local
Wed Nov 01 20:41:30 mona@dhcp-wifi-8021x-155-41-82-88:~$ sudo chown -R $(whoami) /usr/local
Password:
chown: /usr/local: Operation not permitted
系统信息：
Wed Nov 01 20:42:36 mona@dhcp-wifi-8021x-155-41-82-88:~$ uname -a
Darwin dhcp-wifi-8021x-155-41-53-197.bu.edu 17.0.0 Darwin Kernel Version 17.0.0: Thu Aug 24 21:48:19 PDT 2017; root:xnu-4570.1.46~2/RELEASE_X86_64 x86_64
和
Wed Nov …