AVIFrate is an utility that allows you to change many important fields in an avi file header. Most often you need to adjust the Frame rate of the avi video stream. The frame rate is determined when you play a file by simple formula:
fps=dwRate/dwScale
where fps is "frames per second" Playback speed, dwRate and dwScale are fields of the video stream header
After you change these values, AVIFrate will re-calculate frame rate and will allow you to write it directly into the file header. You can undo changes made until you Exit AviFrate. This allows you to try out some values before you decide to keep them.
Next important thing to change is so-called fourcc field. It is used by Windows to determine which codec should be used to decompress video during playback. There are few codecs that have different fourcc field but, in fact, they use the same compression scheme. If you have some other codec that differs from mentioned in an avi header, you may try to change these four characters to meet the expected codec.
