First, let it be known that I hate DIVX. Just want that out of the way. Now on to why and what ....
DIVX is one "flavor" or variation of the newest system made by MPEG (Motion Picture Expert Group). MPEG-1 and MPEG-2 are the "MPEG" format most known, and also carry the format namesake "MPEG". This is just how "DV" format is a "DV" but ended up adopting the format name from it's namesake. Kinda confusing, I know.
The MPEG-4 system is a system by which FourCC codecs compress into a universal "style" of video, and held by a wrapper (or "container") format like AVI. MPEG1 and MPEG2 are standalone formats, and use their ownself for a container. MPEG2 actually has variants too, used in digital satellite and broadcasting (ever seen the word "MP@ML" and others? Well, MP@ML is the DVD kind, but you can have MP@HL and others.
TMPGEnc has some of these settings available.)
... I know I just said a mouthful, but there is not a really easy way to explain the madness that exists in digital video....
Back to DIVX, it is an MPEG-4, known as the 4th generation of MPEG video. MPEG-3 was some speciality format that I forget about, not to be confused with MP3 (which is MPEG Layer III audio).
DIVX uses a harsher compression algorithm and removes much of the signal. It was projected to be the HDTV format of the future, but fell on its face. It mostly used by pirates and hobbyists. Windows Media Video 9, or WMV9 (or a later generation based on WMV9) by Microsoft is now the front-runner for HDTV format, and was approved by SMPTE, the one that chooses video formats in the USA (VHS, DVD, etc). DIVX never caught on in Asia either, outsides of pirates, so it's as good as dead.
Home software encoders can never really produce quality MPEG-4. It takes dedicated hardware systems for good MPEG-4, at least at this point in time. MPEG-4 DIVX/XVID is about where MPEG-2 was in 2000, in terms of qualtiy software and hardware available for the masses.
XVID is the next generation of MPEG-4 using DIVX style codecs, better than DIVX in quality. But it's still a far cry from the abilities of WMV9 (which is yet another MPEG-4 flavor built from the ground up, and not like DIVX/XVID). I don't like Microsoft, but I have to admit there format isn't bad.
DIVX/XVID/WMV are related just like MPEG1/MPEG2 are related. They are variants of each other. DIVX is the oldest and the poorest in quality. DIVX came about in 1999.
... if that good enough, or is there more?
