[FFmpeg-user] Best way to record video on a computer with a really bad CPU yet really good GPU?

[Andy Furniss]

Sven C. Dack wrote:

> The first thing you can do is to reduce the frames that get grabbed per
> second. try this:
>
> $ ffmpeg -f x11grab -s 1920x1080 -i :0.0 -f rawvideo /dev/null
> (I.e. 30fp/s, 2gbit/s)

Seems to default to 30 even if you can go higher.

-f null -

rather than -f rawvideo /dev/null may be more representative.

Either way unless you are using libx264rgb then you would need to add

-pix_fmt yuv420p or for h/w enc -pix_fmt nv12 to bench properly - and
of course if doing s/w enc you still won't know without adding that in.

Even then s/w enc will be wildly variable cpu usage wise depending on
what it's encoding ...