[MEncoder-users] (work-in-progress) XviD encoding guide

[Rich Felker]

On Sat, Jun 25, 2005 at 01:06:26AM +0400, Phil Oleynik wrote:
> Guillaume POIRIER wrote:
> 
> >>True... but the goal here is to gather some feedback about what uses
> >>think about that guide. Hey, we help our dear users (tm) with theirs
> >>problems, so I sincerely hope they'll help me out too on getting a
> >>decent doc, don't you think?
> >>
> >>I think that's fair trade :-)
> >>   
> >>
> >
> >Apparently, I'm the only one to believe in that :-(
> >
> >Doc patch committed: you can find it here:
> >http://mplayerhq.hu/DOCS/HTML/en/menc-feat-xvid.html
> >
> >Guillaume
> > 
> >
> May I ask about describing some options, unlisted in your guide?
> 
> *max_key_interval
> Usually, no one will need it. However, in some cases scene changes very 
> rarely.
> To save details sharpness one may try to lower its value from default.

Lower keyframe interval has nothing to do with sharpness/details.
Lowering the value reduces compression but improves the resolution at
which you can seek.

> *keyframe_boost
> If you encode cartoon/anime, you will need it to get sharper edges with 
> the same
> bitrate.

Huh?!

> *(no)packed
> One of best XviD features, frame swapping. If this is turned on, codec 
> will try to
> swap frames in order to get more quality. Price here is DivX compatibility.

Blatently false. It has nothing to do with quality, just the way the
frames are stored. Packed mode should never be used.

> *(no)closed_gop
> This option also may break compatibility. However, it may save a few bits.

It has nothing to do with quality, really.

> *gmc
> Also, highly dependent from source material. If you have many panoramic
> scenes, this will save a great amount of bits using XviD pan/zoom 
> compressing
> features. This will make your movie decode slower (640*480 24fps pan scene
> may become too hard for Celeron III 800, my own exp.)

I find this hard to believe. Yes it makes it slower, but my K6-3/500
can decode any mpeg4 just fine, even 720x480, including with gmc.

> *chroma_opt
> Yes, it works. It loses quality numerically, but eye is more pleased by 
> resulting
> picture. My eye, at least.

Explain what it does. I assume it reduces chroma precision to save
bits for luma?


Rich