With the two new standard of optical media coming , namely HD-DVD and Blu Ray Disc , there has also come the question of quality and vis-a-vis the codecs they use . Now i have minimal knowledge of the two but from what i have read here and there i hear that HD-DVD uses the progressive format while BLD uses interlaced. That mean HDTV is viewed on a 1080p television while a BLD movie can be viewed(best viewed) on a 1080i screen. Am i right ? Also what are the extensions each format uses ? And the main question , how do you know if a video is interlaced encoded or progressive ? and which method is better in terms of both quality and size ?