The AVI FourCC Code changer allows you to change the FourCC code in an AVI file. The FourCC code is the identification key used by the AVI format to inform itself of which decoder to use for the AVI file playback.

Author Site (support): http://www.videohelp.com/tools/AVI-FourCC-Code-Changer
Download (Windows): http://www.videohelp.com/download/avic100.zip

List of FourCC Codecs is available here : http://www.fourcc.org/codecs.php
Common codecs are :

• MP42 (MPEG-4 variation from Microsoft.
• DIVX (used for versions 4.0 and later of the DivX codec)
• DIV3 (DivX MPEG-4 Low motion codec )
• DIV4 (DivX MPEG-4 Fast motion codec )
• DX50 (Apparently DivX version 5 also encodes using this FOURCC )
• FMP4 (The default MPEG4 format used by FFmpeg tool mencoder )
• MJPG (Motion JPEG video)
• X264 (Used by a popular open source H.264 implementation )
• XVID (XVID MPEG-4)