MPEG-2 is Blurred Compared With Origional AVI File

[x_Jonno_x]

When i am convering an avi file to MPEG-2 format for burning onto a dvd using TMPEng, the picture seems to become slightly blurred compared to the origional avi file. All i can describe it as is some very slight hatching bestween dark/light areas.

Is there any reason for this?

Thanks,

Jonathan