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Quick Solution:
http://www.divx-digest.com/software/divxcodec.html (DivX 3.11 Alpha)
also mirrored here
New: Windows Media Player 12 in Windows 7 can play DivX contents without any additional software.
More Info:
The DivX 3 codec was based on the Microsoft MPEG-4 version 3 codec. Microsoft had locked its own codec so that it could no longer be used to encode AVI’s (it could only encode in Microsoft’s proprietary ASF format). DivX 3 is an alteration that re-enables AVI encoding (albeit with a different name and fourcc).
DivX 3 exists in two versions: a low-motion version (fourcc DIV3), and a fast-motion version (fourcc DIV4 - NOT to be confused with DivX 4). The low-motion codec comes from build 4.1.00.3920 of MS MPEG-4 v3, and the fast-motion codec is from build 4.1.00.3917.
Notes:
- Newer versions of DivX (4, 5, 6, 7), and 3ivx can decode DivX 3 contents
- Installing DivX 4, 5, 6, or 7 will erase the DivX 3 codec from your add/remove programs list if you have it. To have both of them co-exist, install DivX 3 AFTER you install 4, 5, 6, or 7.
- a divx 3.22 beta codec also exists, but it’s just divx 3.11 with the scene detect patch.
Keywords: DIV3, DIV4, DivX 3, DivX 3.11