Movie File Question

[hungrylilboy]

why when i convert a mpeg or avi file to a wmv file the sound and image quality is exactly the same, the image size is slightly smaller in some cases but the size is at least half or more less than before

clearer explanation:

filea.avi (459MB), good sound, good video

filea_new_after_converting.wmv (94MB), exactly the same sound, exactly the same video. Maybe a little smaller image.

[4play]

mpeg is an old technology.

wmv uses mpeg4 which is newer and better at crunching down video but requires a faster machine to play it back.

[hungrylilboy]

the same for avi files?