Ubuntu – How to automatically segment video using ffmpeg without re-encoding

Thanks for the info about order of options @bodhi.zazen and @LordNeckbeard. Apparently the libvpx encoder is a little more picky about that. When I added -threads option after -c:v libvpx, it visibly uses more cores according to top.

-threads 0 only uses 1 core, -threads 8 uses 2 cores, and -threads 16 uses 4 cores. I've tried using a higher number, but the encoder says more than 16 threads is not recommended, and doesn't use any more CPU. Encoding speed itself is about twice as fast now. Thanks again for the help!

It looks like it runs ffmpeg and so instead of this:

ffmpeg -i inputfile.mp4 -vf reverse reversed.mp4

and this:

ffmpeg -i inputfile.mp4 -vf reverse -af areverse reversed.mp4

Run this instead:

-i inputfile.mp4 -vf reverse reversed.mp4

and this:

-i inputfile.mp4 -vf reverse -af areverse reversed.mp4

https://video.stackexchange.com/a/17739

Thanks LordNeckbeard!

It looks like this only works for ffmpeg commands and so commands like cat won't work.

I didn't look at it too close but it looks like if you try to run cat you would really be running ffmpeg cat which does not exist.

You see, if you run -i input.mkv -an -qscale 1 %06d.jpg from a terminal, this does nothing but if you run ffmpeg -i input.mkv -an -qscale 1 %06d.jpg it does. This indicates that this application runs ffmpeg and allows you to add the option -i input.mkv -an -qscale 1 %06d.jpg to the ffmpeg command.