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

[Phil Oleynik]

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.

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


*kfreduction
No human is able do distinguish how bad rapid flashing frames were 
compressed,
but it is hard task for codec. With this option only the last frame from 
series of
flashes will get full bitrate.

*kfthreshold
Is the window where serial keyframes are treated with *kfreduction

*(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.

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

*qpel
Option, that should be used for high quality streams, it may do good, or 
may
do bad to your movie. Highly dependent from source material.

*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.)

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

*hq_ac
Unfortunately cannot say anything how it works, but it makes picture better,
perceptually. This option must be further investigated, I do not know 
how it works.

Philipp