From ECDL.web

Blu-ray Disc is a high density optical disc storage medium designed to supersede the DVD format. The name Blu-ray Disc refers to the blue laser used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs. The standard physical medium is a 12 cm plastic optical disc, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs (50 GB) the norm for feature-length video discs and additional layers possible in the future.

During the high definition optical disc format war, Blu-ray Disc competed with the HD DVD format. Toshiba, the main company that supported HD DVD, conceded in February 2008.

[edit] Variants

• The Mini Blu-ray Disc (also, "Mini-BD" and "Mini Blu-ray") is a compact 8 cm (~3 in)-diameter variant of the Blu-ray Disc that can store approximately 7.5 GB of data. It is similar in concept to the MiniDVD and MiniCD. Recordable (BD-R) and rewritable (BD-RE) versions of Mini Blu-ray Disc have been developed specifically for compact camcorders and other compact recording devices.
• Blu-ray Disc recordable refers to two optical disc formats that can be recorded with an optical disc recorder. BD-Rs can be written to once, whereas BD-REs can be erased and re-recorded multiple times. Since September 2007, BD-RE is also available in the smaller 8 cm Mini Blu-ray Disc size.
• BDXL supports 100GB and 128GB write-once discs and 100GB rewritable discs for commercial applications. It was defined in June 2010. BDXL discs are not compatible with existing BD drives.

[edit] Software standards

[edit] Filesystem

Blu-ray Disc specifies the use of Universal Disk Format (UDF) 2.50 as a convergent friendly format for both PC and consumer electronics environments.

[edit] Directory and file structure

All BD-ROM application files are stored under a “BDMV” directory which contains:

• a PLAYLIST directory: the Database files for Movie PlayLists.
• a CLIPINF directory: the Database files for Clips.
• a STREAM directory: contains Audio/Video stream files.
• an AUXDATA directory: Sound data files and Font files.
• a BACKUP directory: contains copies of the "index.bdmv” file, the “MovieObject.bdmv” file, all the files in the PLAYLIST directory and all files in the CLIPINF directory.
• index.bdmv file: stores information describing the contents of the BDMV directory.
• MovieObject.bdmv file: stores information for one or more Movie Objects.

[edit] Media format

Audio, video and other streams are stored on Blu-ray Discs in a container format based on the MPEG transport stream. It is also known as BDAV MPEG-2 transport stream and can use filename extension .m2ts.Blu-ray Disc titles authored with menu support are in the BDMV (Blu-ray Disc Movie) format and contain audio, video, and other streams.

High-definition video may be stored on BD-ROMs with up to 1920×1080 pixel resolution at up to 59.94 fields per second, if interlaced. Alternatively, progressive scan can go up to 1920×1080 pixel resolution at 24 frames per second, or up to 1280x720 at up to 59.94 frames per second

For audio, BD-ROM players are required to support Dolby Digital (AC-3), DTS, and linear PCM. Players may optionally support Dolby Digital Plus and DTS-HD High Resolution Audio as well as lossless formats Dolby TrueHD and DTS-HD Master Audio.

At the 2005 JavaOne trade show, it was announced that Sun Microsystems' Java cross-platform software environment would be included in all Blu-ray Disc players as a mandatory part of the standard. Java is used to implement interactive menus on Blu-ray Discs, as opposed to the method used on DVD-video discs. DVDs use pre-rendered video segments and selectable subtitle pictures, which are considerably more primitive and rarely seamless.

[edit] Region codes

As with the implementation of region codes for DVDs, Blu-ray Disc players sold in a specific geographical region are designed to play only discs authorized by the content provider for that region. This is intended to permit content providers (like movie studios) the ability to support product differences in content, price, release date, etc. by region. According to the Blu-ray Disc Association, all Blu-ray Disc players and Blu-ray Disc-equipped computer systems are required to support regional coding.

The Blu-ray Disc region coding scheme divides the world into 3 regions, labeled A, B, and C.

• Region A includes most North, Central and South American and Southeast Asian countries plus Taiwan, Japan, China Hong Kong, China Macau and Korea.
• Region B includes most European, African and southwest Asian countries plus Australia and New Zealand.
• Region C contains the remaining central and south Asian countries, as well as the People's Republic of China and Russia.