HD DVD Glossary
Advanced Access Control System – the protection scheme used by HD DVD. For full specifications see the AACS site.
High resolution audio and video and also iHD interactivity, allowing much greater control of the titles (e.g. menus while the movie is running, PIP (picture-in-picture), downloadable content, etc).
Analog method of connecting players and displays up to 1080i resolution.
Digital Only Token - a flag on the disc that will disable all analog outputs. No title uses this and there are severe restrictions on using it in the future. This is an AACS feature shared with Blu-ray.
The process of taking a DVD (which is encoded at 480i) and converting it to a higher output resolution (e.g. 1080i). Up-conversion is limited to 480p via an analog connection due to CSS licencing rules.
Digital Video Interface, a digital way of connecting players and displays. HDCP is optional on DVI connections.
Video codec defined within the MPEG4 standard.
High Definition Content Protection - a way of protecting a digital video signal.
HD Interactive – this is the Microsoft implementation of the declarative and procedural programming system used on Advanced Content HD DVDs.
High Definition Multimedia Interface – Like DVI but adds audio channels and HDCP. See the HDMI site.
Special dual-format disc that contains both old-fashioned DVD and new HD DVD content. Hybrid discs can be double-sided i.e. a flipper) or dual layer (all content on the same side of the disc).
Image Constraint Token - a flag on a disc that forbids it to be played at a high resolution over an unprotected analog signal e.g. component video. Content has to be down-rezzed to 960x540, which while lower than full HD is still better than DVD. Studios have the option to use this on any title but none have, and frankly none are likely too any time soon - there are there too many HDTVs lacking HDCP. This is an AACS feature shared with Blu-ray.
The old name for HDi.
This is a feature which allows legal copies to be taken of a disc for use on your home network, or on portable devices. This requires a player that can do it and a disc that allows you to.
Video codec used on DVDs and included in the HD DVD standard. However it is not very popular for HD content due to its lower picture quality and higher space requirements.
Basically DVDs with high resolution video and more capacity but little else (specifically no HDi).
Advanced Video Codec based on Windows Media Video. The majority of HD DVD titles use this as it offers the best picture quality, lowest space requirements and good quality tool support.