I have the DivX 5.1.1 decoder and Nic's XviD binary from 16/07/03 installed. I noticed that the DivX codec is able to decode my movies encoded with XviD. Is it better to use the DivX decoder or the XviD decoder? I thought it would be better to use the XviD decoder so I went into the DivX config utility and disabled "Support generic Mpeg-4". Should I leave this enabled instead?

I also have some movies downloaded that say they are XviD in the filename, however, the DivX codec is being used to decode them even with the XviD codec installed. I looked at them with Gspot and got some confusing results:

4CC: DX50/xvid
Name: DivX 5.0

Then it displays 2 compatible codecs which are both "DivX Decoder Filter".

So are these files DivX or XviD?

One last thing, I tried installing Koepi's "XviD-1.0-Beta3-26122003.exe" and it worked except all my video was upside down. Are there still many problems with this?

try ffdshow. as long as you have both encoders installed ffdshow should take care of the rest. its on sourceforge somewhere.

otherwise, i prefer XviD, but use whatever one you choose. they should both work unless you encode using GMC, in which case DivX may not decode correctly.

What exactly is ffdshow? I was under the impression it is a standalone decoder that can decode XviD and DivX but with less quality?

ffdshow is a stand alone decoder for DivX, XviD and all MPEG-4 implementations in general. There should be no discernable quality differences between them. The XviD decoder isn't finished and still nees a fair bit of work. DivX is quite capable of decoding XviD but is generaly accepted to be slower than ffdshow.