[MPlayer-dev-eng] Support code for latest XViD CVS code commited

[Rémi Guyomarch]

I just committed code to support the latest dev-api-3 CVS branch from
the XViD project. This is based on a patch by Marco "elcabesa" Belli
<elcabesa at inwind dot it>. This code enable you to play with GMC,
quarter pixel ME, B-frames, half-resolution U&V encoding and something
called "me_colour".

Be warned that everything in this list is currently buggy and/or not
finished. At least you can play with them with mencoder :)

So, in short, if you want a fast, stable high-quality and highly
configurable mpeg4 codec, use libavcodec. It's still and by a large
margin the prefered codec for mencoder.

At the same time I changed a few things in the code used by the stable
XViD library :
- option "br" is now "bitrate", mencoder / mplayer use long options ;
- option "quality" is now "me_quality" since this better describe what
this option does ;
- "4" is now the default for "me_quality" since it seems it's the best
encoding speed / bandwdith used ratio ;
- added a "4mv" option, off by default. This was previously included
in quality=4,5,6. This is to be roughly in line with libavcodec.

      before             now
    (nothing)      me_quality=6:4mv
    quality=6      me_quality=6:4mv
    quality=5      me_quality=5:4mv
    quality=4      me_quality=4:4mv
    quality=3      me_quality=3
    quality=2      me_quality=2
    quality=1      me_quality=1


Now, a few notes about the dev-api-3 XViD CVS branch :

* the last MB (bottom-left corner) isn't encoded properly
  this looks like the hinted ME bug in the stable tree but now it's
  there everytime

This bug alone makes the current XViD CVS code rather unusable...

* quarterpel increase encoding time by a significant margin and
  sometimes bandwidth too, also I got crashes while playing a sequence
  encoded with quarterpel
* bframes :
	- incompatible with the external VBR code
	- makes the **internal** VBR code behaves funny
	- increase bandwidth
* gmc very slightly increase bandwidth
* me_color gives a very very small bandwidth reduction in exchange of
  a significant slowdown 
* 'reduced' gives an enormous boost in encoding speed at the cost of
  an enormous decrease in quality and a rather strange looking decoded
  image :)

-- 
Rémi