[FFmpeg-user] After reading x264 Encoding Guide, some questions

Francois Visagie francois.visagie at gmail.com
Fri Dec 7 13:03:05 CET 2012

Hi All,


First of all, a great thank you to the author/s of this guide. It's short
but still thorough and very helpful.


I have some questions remaining that don't seem to be covered in the
documentation available that I would like to clear up.


1. The guide refers to the -crf and -qp options but neither is covered in
http://www.ffmpeg.org/ffmpeg.html. What is their relationship to each other
and when is it advisable to use which? How do these two relate to the q=nn.n
printed after encodes?


2. I seem to recall reading somewhere that the use of presets has been or is
being deprecated in favour of profiles(?). Is this merely to avoid
cluttering presets with obsolete stuff and only using them for selective
over-rides when absolutely necessary?


3. I'm trying to understand the relationship between x264opts and other
"libx264 AVOptions" in ffmpeg -h. If I understand correctly, x264opts are
passed to libx264 for parsing and others are parsed by ffmpeg before being
passed to libx264, if I could put it that way? But then, what does it mean
when http://www.ffmpeg.org/ffmpeg.html#Options-4 says

"'passlogfile filename'

Specify filename for 2 pass stats. Deprecated in favor of x264opts (see
stats libx264 option)." - this makes x264opts and libx264 options sound like
the same thing?

4. Both the Encoding Guide and the ffmpeg documentation refer to 'x264
-fullhelp', but ffmpeg does not recognise such a parameter and the "Zeranoe
FFmpeg Builds" do not include that executable. Is one meant to download x264
from videolan.org?


Many thanks,



Francois Visagie



T: +27 (83) 326-4358

F: +27 (86) 511-3490

E: francois.visagie at gmail.com



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