[FFmpeg-user] why reducing the resolution a percentage doesn't reduce the video the same proportion?

Michael Koch astroelectronic at t-online.de
Tue Mar 14 14:30:41 EET 2023

Am 14.03.2023 um 10:37 schrieb Natalia Molinero Mingorance:
> I'm using this command:
> -y -r -i $inVideoUri -movflags faststart -c:v libx265 -s
> $videoResolution -c:a copy -preset ultrafast  $outPutUri"
> However, if "videoResolution" is a 50% of the original video resolution,
> the resulting file size is not 50% of the original one. I assume there are
> some headers or metadata added during the process but I would like to know
> how to estimate the final video size.

You can control the size of the output file by either using the -q:v 
option or by specifying the video bitrate with the -b:v option.

By the way, I don't understand the purpose of the -r option in your 
command line. Shoudn't that give an error message if it's not folllowed 
by a value?


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