What is Blu-ray?

Blu-ray, also known as Blu-ray Disc (BD), is the name of a new optical disc format jointly developed by the Blu-ray Disc Association (BDA), a group of the world’s leading consumer electronics, personal computer and media manufacturers (including Apple, Dell, Hitachi, HP, JVC, LG, Mitsubishi, Panasonic, Pioneer, Philips, Samsung, Sharp, Sony, TDK and Thomson). The format was developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data. The format offers more than five times the storage capacity of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc. This extra capacity combined with the use of advanced video and audio codecs will offer consumers an unprecedented HD experience.

Blu-ray formats planned

As with conventional CDs and DVDs, Blu-ray plans to provide a wide range of formats including ROM/R/RW. The following formats are part of the Blu-ray Disc specification:

BD-ROM—read-only format for distribution of HD movies, games, software, etc.

BD-R—recordable format for HD video recording and PC data storage.

BD-RE—rewritable format for HD video recording and PC data storage.

There’s also plans for a BD/DVD hybrid format, which combines Blu-ray and DVD on the same disc so that it can be played in both Blu-ray players and DVD players.

Data fit on a Blu-ray disc

A single-layer disc can hold 25GB.

A dual-layer disc can hold 50GB.

To ensure that the Blu-ray Disc format is easily extendable (future-proof) it also includes support for multi-layer discs, which should allow the storage capacity to be increased to 100GB-200GB (25GB per layer) in the future simply by adding more layers to the discs.

Video codecs Blu-ray support

MPEG-2 – enhanced for HD, also used for playback of DVDs and HDTV recordings.

MPEG-4 AVC – part of the MPEG-4 standard also known as H.264 (High Profile and Main Profile).

SMPTE VC-1 – standard based on Microsoft’s Windows Media Video (WMV) technology.

Please note that this simply means that all Blu-ray players and recorders will have to support playback of these video codecs, it will still be up to the movie studios to decide which video codec(s) they use for their releases.

Audio codecs Blu-ray support

Linear PCM (LPCM) – up to 8 channels of uncompressed audio. (mandatory)

Dolby Digital (DD) – format used for DVDs, 5.1-channel surround sound. (mandatory)

Dolby Digital Plus (DD+) – extension of Dolby Digital, 7.1-channel surround sound. (optional)

Dolby TrueHD – lossless encoding of up to 8 channels of audio. (optional)

DTS Digital Surround – format used for DVDs, 5.1-channel surround sound. (mandatory)

DTS-HD High Resolution Audio – extension of DTS, 7.1-channel surround sound. (optional)

DTS-HD Master Audio – lossless encoding of up to 8 channels of audio. (optional)

Please note that this simply means that Blu-ray players and recorders will have to support playback of these audio codecs, it will still be up to the movie studios to decide which audio codec(s) they use for their releases.

Variants

Mini Blu-ray Disc

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

“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. The current practical maximum speed for Blu-ray Discs is about 12×. Higher speeds of rotation (10,000+ rpm) cause too much wobble for the discs to be written properly, as with the 20× and 52× maximum speeds, respectively, of standard DVDs and CDs.

Since September 2007, BD-RE is also available in the smaller 8 cm Mini Blu-ray Disc size.

On September 18, 2007, Pioneer and Mitsubishi codeveloped BD-R LTH (“Low to High” in groove recording), which features an organic dye recording layer that can be manufactured by modifying existing CD-R and DVD-R production equipment, significantly reducing manufacturing costs. In February 2008, Taiyo Yuden, Mitsubishi, and Maxell released the first BD-R LTH Discs, and in March 2008, Sony’s PlayStation 3 gained official support for BD-R LTH Discs with the 2.20 firmware update. In May 2009 Verbatim/Mitsubishi announced the industry’s first 6X BD-R LTH media, which allows recording a 25 GB disc in about 16 minutes.

Unlike the previous releases of 120 mm optical discs (i.e., CDs and standard DVDs), Blu-ray recorders hit the market almost simultaneously with Blu-ray’s debut.

BD9 and BD5

The BD9 format was proposed to the Blu-ray Disc Association by Warner Home Video as a cost-effective alternative to the 25/50 GB BD-ROM discs. The format was supposed to use the same codecs and program structure as Blu-ray Disc video, but recorded onto less expensive 8.5 GB dual-layer DVD. This red-laser media could be manufactured on existing DVD production lines with lower costs of production than the 25/50 GB Blu-ray media.

Usage of BD9 for releasing content on “pressed” discs has never caught on. After the end of the format war, major producers ramped up the production of Blu-ray Discs and lowered their prices to the level of DVDs. On the other hand, the idea of using inexpensive DVD media became popular among individual users. A lower-capacity version of this format that uses single-layer 4.7 GB DVDs has been unofficially called BD5. Both formats are being used by individuals for recording high definition content in Blu-ray format onto recordable DVD media.

Despite the fact that the BD9 format has been adopted as part of the BD-ROM basic format, none of the existing Blu-ray player models support it explicitly. As such, the discs recorded in BD9 and BD5 formats are not guaranteed to play on standard Blu-ray Disc players.

AVCHD and AVCREC also use inexpensive media like DVDs, but unlike BD9 and BD5 these formats have limited interactivity, codec types, and data rates.

BDXL

The BDXL format supports 100 GB and 128 GB write-once discs and 100 GB rewritable discs for commercial applications. It was defined in June 2010.

BD-R 3.0 Format Specification (BDXL) defined a multi-layered disc recordable in BDAV format with the speed of 2× and 4×, capable of 100/128 GB and usage of UDF2.5/2.6.

BD-RE 4.0 Format Specification (BDXL) defined a multi-layered disc rewritable in BDAV with the speed of 2× and 4×, capable of 100 GB and usage of UDF2.5 as file system.

BDXL discs are not compatible with existing BD drives, though a firmware update may be available for some newer drives.

IH-BD

The IH-BD (Intra-Hybrid Blu-ray) format includes a 25 GB write-once layer (BD-R) and a 25 GB read-only layer (BD-ROM), designed to work with existing Blu-ray Discs.

Region codes

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 (motion picture studios, etc.) to do effective price differentiation between regions. 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.” However, “Use of region playback codes is optional for content providers…” Some current estimates suggest 70% of available [movie] Blu-ray Discs from the major studios are region-code-free and can therefore be played on any Blu-ray Disc player, in any region.

Movie studios have different region coding policies. Among major U.S. studios, Warner Bros., Paramount Pictures, Universal Studios, Sony Pictures and Walt Disney Pictures have released most of their titles region-free. MGM and Lions Gate Entertainment have released a mix of region-free and region-coded titles. 20th Century Fox have released most of their titles region-coded.

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

Region Code	Area
A	Includes most North, Central and South American and Southeast Asian countries plus Taiwan, Japan, Hong Kong, Macau and Korea.
B	Includes most European countries, African and Southwest Asian countries plus Australia and New Zealand.
C	Includes the remaining central and south Asian countries, as well as China and Russia.