[x264-devel] preset veryfast always generates lower bitrate than veryslow. Why and how to fix?

[Henrik Gramner]

On Fri, Nov 25, 2016 at 4:04 PM, Alex KAS <alex-kas at altaray.net> wrote:
> I encoded literally 34 videos in a raw. All the time the command line
> was identical (-crf 22, etc) apart from filenames and the -preset setting.
> Every time I got that veryfast creates a file of the smallest size.
> Even less than placebo or veryslow

I believe the underlying misunderstanding here is the assumption that
CRF guarantees a specific constant "quality" (however you chose to
define that term) regardless of other settings. It doesn't.

The average quality:bitrate ratio will improve with slower settings,
but that doesn't mean that the file size will decrease for any given
CRF value.

It's completely normal to get a smaller output file size when using
faster encoding settings, but the quality will also be worse.