when ''save myavi'' the size of it in matlab folder much more than the size of original video?

Hello everyone,

     I have a avi 320x240, 20 sec., 7.5 mb. but when i save ''save myavi''(after myavi=aviread('mov'); ), the form of it in matlab folder (as MAT-file), it shows 88,mb. what information gets involved?
                                                       much appreciated.

[Matt Kindig]

The compression algorithm for an AVI and a MAT file is quite different. In particular, identical pixels which occur in many frames (background regions, for example) will usually compress in the AVI format. As Matlab doesn't know that the particular 4-D matrix is an AVI file, no such compression takes place, resulting in a larger file.