[MEncoder-users] lavc & h.264

[Philippe MONROUX]

De (from) (von) <raimund.berger at gmail.com> :
 
> > It seems you are kind of going a bit astray here.
> > First, autoaspect has little or nothing to do with speed. 

astray..presumably. But it because of the doc in which it's written

http://www.mplayerhq.hu/DOCS/HTML/en/aspect.html

13.10. Preserving aspect ratio
...
Rescaling the movie is disgusting and
time consuming, there has to be a better way! 
^^^^^^^^^^^^^^

so I believed that libavc opts autoaspect was more quick.

> It's just a comfort feature for aspect ratio calculation, which you
> can do by hand if you wish. I wouldn't try that with the actual
> encoding.
> 
> Second, both the mencoder builtin and the lavc h264 encoders rely on an
> external library, namely libx264, to do the grunt work. Since by far the
> most cpu time is spent on the encoding, it's of little matter which of
> those stubs you use. So to answer your initial question regarding the
> speed difference - no, there is none, since all the hard work is done in
> libx264.
> 
> Third, the lavc x264 stub implements it's own x264 option
> mappings. That's what you apparently found out, but unfortunately didn't
> yet bother to further investigate in the docs. If you had, you would
> have found out that the information you want is already there in the man
> page resp. the online docs.
> 
> Fourth, if you plan to regularly update your libx264 library maybe even
> by pulling from the x264 git repo, I'd recommend *not* using the lavc
> stub. Why? Because, due to those option mappings, it's usually a little
> behind latest x264 developments. The x264encopts on the other hand are
> just passed through to libx264, so that stub is very likely to work with
> the very latest x264 version.

Thanks for the advice

-- 
philippe