How to capture a timed screen recording on a Mac with ffmpeg

Question

I\'m on a Mac with MacOS Sierra installed. I\'ve installed ffmpeg with homebrew. I list my devices via:

ffmpeg -f avfoundation -list_devices true -i \"\"


        

Answer 1

I guess most of the time we'll ignore the program warnings, but not this one.

If recording screen with no other options like this:

ffmpeg -f avfoundation -i "1" out.mov

You'll probably see some warnings:

[mov @ 0x7f7fcf19da00] Frame rate very high for a muxer not efficiently supporting it.
Please consider specifying a lower framerate, a different muxer or -vsync 2
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
......
[mov @ 0x7f7fcf19da00] WARNING codec timebase is very high. If duration is too long,
file may not be playable by quicktime. Specify a shorter timebase
or choose different container.

And the output video stream fps will be 1000k, which is unreasonable.

So I set the fps option. Also I set pixel format to yuv420p, otherwise the default yuv422p color space cannot be played by quicktime:

ffmpeg -f avfoundation -i "1" -pix_fmt yuv420p -r 25 -t 5 out.mov

I'm using a 2013-mid MBP with MacOS sierra, also brew installed ffmpeg 3.1.1.