Comparison of high definition optical disc formats Blu-ray disc players since the end of the format war. Blu-ray Disc has a higher maximum disc capacity than HD DVD (50 GB vs. 30 GB for a double layered disc). In September 2007 the DVD Forum approved a preliminary specification for the triple-layer 51GB HD DVD (ROM only) disc though Toshiba never stated whether it was compatible with existing HD DVD players. In September 2006 TDK announced a prototype Blu-ray Disc with a capacity of 200GB. TDK was also the first to develop a Blu-ray prototype with a capacity of 100GB in May 2005. In October 2007 Hitachi developed
Optical disc packaging for DVD-Audio, and as of mid-2006, the case format for all albums released by the Universal Music Group in Europe. Many alternatives to the standard jewel case may also be found, including larger DVD-style cases with a more book-like shape. It is not uncommon to find CDs housed in custom cases, tins and boxes of varying shapes and sizes. Slipcases and other envelope-type designs are also occasionally used. Some DualDiscs are packaged in jewel cases of a somewhat different design from the CD version; the inside edge is rounded instead of flat, and the physical position of the disc is