BD9 / Mini-Blu-ray Disc
BD9 is a red laser DVD with BD contents on it. This disc should be rotated at 3x speed or more to satisfy the minimum transfer rate of 30.24 Mbit/s. These disks can be used for private storing and can be authored even without implementing AACS. BD9 was originally proposed by Warner Home Video, as a cost-effective alternative to regular Blu-ray discs. It is similar to HD DVD's 3x DVD
Blu-ray Disc recordable
Blu-ray Disc recordable refers to two optical disc formats that can be recorded with an optical disc recorder. BD-R discs can be written to once, whereas BD-RE can be erased and re-recorded multiple times. As of March 2007, BD-R/RE drives up to 4x retail are sold for about US$600 and 2x single-layer BD-R discs, with a capacity of 25 GB, can be found for around US$12. The theoretical maximum for Blu-ray Discs is about 12x as the speed of rotation (10,000 rpm) causes too much wobble for the discs to be read properly, similar to the 20x and 52x respective maximum speeds of DVDs and CDs.
HD DVD / Blu-Ray hybrid discs
Warner Bros. officially announced Total Hi Def (THD) at CES 2007. Total Hi Def (Total HD) hybrid discs supports both HD DVD and Blu-ray, HD DVD on one side (up to two layers) and Blu-ray on the other side (up to two layers). Despite initially announcing that Total HD would be ready by the second half of 2007, on June 27, 2007, Warner Bros. issued a press release stating that they would be delaying the launch of Total HD discs until early 2008. As of September 2007, no specific titles have yet been announced.