[FFmpeg-user] libx264 very bad scaling with 4 real CPU cores (no HT)

Moritz Barsnick barsnick at gmx.net
Fri Dec 4 12:52:16 CET 2015

On Fri, Dec 04, 2015 at 12:06:24 +0100, D wrote:
> mailing list or forum (they link to doom10 which doesn't exist, LOL) or

doom9 perhaps?

> The other thing I find weird with -preset is that one can use -crf 
> setting with it. I thought a preset would cover this and no -crf setting 
> would be needed/allowed. But because it is, the question is what other 
> settings are allowed/needed? Confusing.

As far as my experience tells me, the presets control speed versus
size, at (approximately) constant quality. So "-preset veryslow" and
"-preset ultrafast" should show the same image quality. There are test
measurements out there to prove it, IIRC. You then use "-crf" to vary
the requested quality.

Indeed, asking x264 folk would be better. :)


More information about the ffmpeg-user mailing list