For weeks now I have been trying to identify why my HD content to sd content looks so great in Premiere pro and bad when it is exported. Today I was exporting some sd footage, 720x576 and noticed that the poor quality was aparrant here too. It looks as if a grainy overlay has been added with fine vertical lines, it is very difficult to describe. If have tried lots of different presets, both custom and suggested but this is noticeable on all of them. What is going on, please help!!!
If you edit a DV clip in a DV sequence and export to a DV file and there are quality problems then your workstation is in bad shape and you may have to wipe it and re-install everything.
I sincerely hope you have not installed any "codec packs".
Otherwise, please provide these details to help us help you.