Troubleshooting AVI

Why doesn't my AVI file play?

There are many reasons why an AVI file will not play. The MOST COMMON reason that an AVI file will not play is that the video codec (compressor/decompressor) used by the AVI file is not installed on the system being used to attempt to play the file. Usually, the Windows operating system, Windows Media Player, or the application that you are using will report an error indicating that the codec is not present or that it cannot find the codec needed. Video codecs are identified by a four character code such as IV50 or DVSD. Missing video codecs and video codecs in general are discussed in a number of places in the AVI Overview including: Most Common AVI Question: What does "could not find vids:xxxx ..." error mean? The AVI Overview contains extensive information on four character codes. Link to Section on Four Character Codes Return to Top

Why doesn't my AVI file play back from a CD Reader or DVD Reader?

There are many reasons why an AVI file will not play. Always make sure that you have the required video codec installed. Usually Windows or your application will report an error if the required video codec is not installed or cannot be located. An uncompressed or barely compressed AVI file can exceed the bandwidth of hardware especially slower peripherals such as a CD Reader or DVD Reader. The characteristic symptom is that a few frames of the AVI may play before the AVI freezes. Other symptoms are possible. An uncompressed 640 by 480 30 frames per second true color (24 bit color) AVI file has a bit rate of about 221 Megbits per second. (640 * 480 * 30 * 24 bits/pixel). You can easily exceed the bit rate of even a fast CD Reader (e.g. 50x which is only about 60 Mbits/second) with an uncompressed or barely compressed AVI. Make sure the bit rate of the AVI file is not exceeding the bandwidth of either your CD player or possibly the system bus if playing from a hard drive, before looking for more exotic causes. Similar problems can occur with a DVD player, although the base speed of a DVD player is higher than a CD Player. Return to Top NOTE: Suggestions, additions, and corrections are welcome. Please send to
© 1996-2002 by John F. McGowan, Ph.D. Disclaimer