[FFmpeg-user] How can I reduce the cpu usage of ffmpeg?

Moritz Barsnick barsnick at gmx.net
Sat Jan 10 20:07:25 CET 2015

On Sat, Jan 10, 2015 at 18:44:07 +0000, Nicholas Robbins wrote:
> ( sleep 10s ; cpulimit -z -e ffmpeg -l 95 ) &

> That should start and not wait to finish (a timer of 10 seconds and
> then run the cuplimit command) and then continue on with your script.

I would have suggested that too, or something like suggested here:
though I think there's an error in there.

$ ffmpeg ... & (sleep 2 && cpulimit -z -e ffmpeg -l 95)

Note that I believe the example given in the link requires a double-'&'
after sleep. I use brackets just to go sure.

Even better: cpulimit accepts a PID. If ffmpeg doesn't do crazy fork
magic (which I believe it doesn't), you should be able to tell cpulimit
to pick up ffmpeg's pid. In a Bourne shell, when you background a
process, this PID is stored in "$!".

$ ffmpeg ... &
$ cpulimit -l 95 -p $!

Enough Unix magic (= basics ;-)) for today.


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