Blu-ray Disc

 

    Blu-ray (Blu-ray Disc or BD) is an digital multimedia optical disc format developed by Sony and the Blu-ray Disc Association. It is the successor of the DVD and the CD, and it was designed to store and play high-definition movies, surround sound music, and rich interactive content.





Blu-ray Disc
Blu-ray Disc.svg
BluRayDiscBack.png
Reverse side of a Blu-ray. Unlike CD and DVD, the reflection has a blue hue. Different brands of disc can have different colors, such as silver, gold, or grey.
Media type
  • High-density multimedia optical disc
Capacity
  • 25 (single-layer)
  • 50 (dual-layer)
Block size
  • 2 KB sector,[1] 64 KB ECC-block[1][2]
Read mechanism
  • 405 nm diode laser, 36 Mbit/s
Write mechanism
  • 405 nm diode laser with a focused beam using more power than for reading
Developed by
Dimensions
  • 12 cm (4.7) diameter
  • 1.2 mm (0.047 in) thickness
Usage
  • High-definition video
  • High-resolution audio
  • Stereoscopic 3D
  • Interactive apps and games
  • Data storage
Extended from
  • DVD
Extended to
  • Ultra HD Blu-ray
  • Archival Disc
Released
  • 2003

Physical Disc

While CDs have 700MB of data and dual-layer DVDs have 8.5GB of data, each layer of a BD offers 25GB and has a continuous spiral track. A dual-layer BD has 50GB of data storage. High-definition video and uncompressed audio with very high bitrates take up space, so the disc storage capacity is very large and necessary. 

 The Blu-ray's physical structure and layout are complex and more advanced than the CD and DVD. A Blu-ray disc is the same size as an average CD and DVD (12 cm (4.7 in)) long and 1.2 mm thick and has an ultra-hard yet skinny polymer coating to prevent scratches and damage. The disc is made from many materials, polycarbonate for the substrate, polycarbonate film, silicone, and others for the cover layer, aluminum or silver alloy for the reflective layer, silicon nitride for the moisture barrier, pressure sensitive adhesive, photocurable acrylate adhesive, and others for the space layer, and silicon dioxide resin, silicone and others for the protective hard coating. 

There are three kinds of Blu-ray Discs, prerecorded (BD-ROM), recordable (BD-R) and rewritable (BD-RE).

 

BD-ROMs

BD-ROMs (Read-Only Memory) is a a variant with data permanently molded (pressed) into them at the factory and is typically used to distribute commercial movies and albums. Another reason why they're called "BD-ROMs", because it was designed to be an all-in-one multimedia format, so there not officially called "BD-Video, BD-Audio, etc." like the naming conventions of the CD and DVD.

Studios must have a license from the BDA to officially manufacture and sell BD-ROMs.

 

BD-Rs & BD-REs

A BD-R (recordable) is a recordable variant of Blu-ray aimed at consumers (and TV broadcasters) to burn or record video/audio and store data. It is a write-once format employing inorganic material (organic dye) recording layer to which information is written (burnt) using a laser. A BD-RE (rewritable) is similar to BD-Rs except it's a rewritable format incorporating a recording layer composed of a phase-change alloy that can be rewritten at least a thousand times.

BDXL is a variant of BD-R/BD-RE, but offers 100GB storage, however, it's not compatible with standard BD players and drives, and will need a BDXL compatible player or drive.

 

History

On April 10 2003, Sony introduced the BDZ-S77, the first Blu-ray recorder (burnable BD-Rs/BD-REs) designed for households. It was priced at US$3,800 and targeted toward the Japanese consumer markets to record or play recordable content. At the time, the product took advantage of the digital satellite broadcasting that was bringing HDTV to more and more households. 

On June 25 2006, Samsung released the first BD-ROM player, the Samsung BD-P1000, months after HD-DVD launched, priced at US$999.99. The first Blu-ray Disc launch titles were released on June 20, 2006: 50 First Dates, The Fifth Element, Hitch, House of Flying Daggers, Underworld: Evolution, xXx (all from Sony), and MGM's The Terminator.

From 2006 to 2008, Sony's Blu-ray competed with Toshiba's HD-DVD and won. Blu-ray emerged victorious in the format war, but not without consequences. It never replaced the DVD because the rivalry caused much confusion to normie consumers (especially Americans) as they couldn't tell the difference between the two, and many thought HD DVDs played on standard DVD players.

When the first Blu-ray disc players launched (Samsung BD-P1000, Sony BDP-S1), they mostly received positive reviews for their superior image quality, immersive sound, and interactive features. However, they also faced some criticism. Initially, the players were slow to load content, the price was high, there were playback glitches, a few launch titles to choose from, and some models were incompatible with CDs. Today, newer players have improved over the years and are usually affordable. According to Blu-ray.com (not affiliated with BDA), there are over 20,000 Blu-ray titles.


 

Application Formats

BD-ROMs use the BDMV application format to meet the standard requirements for distributing high-definition commercial movies, surround sound music, and Java video games. For menus and interactive software, BDMV applications have two 32-bit play modes, HDMV mode and BD-J mode. These modes are more advanced than primitive DVD menus.

  See: BDMV Application format

BD-ROMs that use non-standard applications and specs (e.g. PS3, Xbox One) are called Data BDs (equivalent to Black Book CD).

BD-Rs/BD-REs commonly use the BDAV Application format for simple DVD-like interactivity, usually for broadcasters, owners of TV recorders, and hobbyist. BDAV (v.5) has three play modes, HDMV TS, HEVC TS, and SESF (Also supports Japan's IDSB broadcasting format). BDMV apps can be burned to BD-Rs/BD-REs. BDAV apps can be converted to BDMV apps (HDMV TS to HDMV only). BDAV interactivity is very similar to DVD.

BD-REs use the RREF (Realtime recording and Editing Format).

Some film labels will release BDMV movie titles in burnt BD-Rs (because it's cheaper without going through licensing with the BDA). It's not illegal or anything, but it's not recommended because since BD-Rs use organic dye it will eventually fade over time, making it a burden for collectors. In contrast, disc storage of a BD-ROM is permanently molded, meaning it will last for a very long time. Also, commercial BD-Rs are NOT allowed to use the Blu-ray disc logo.


Successor

In 2016, Ultra HD Blu-ray (UHD-BD or UHDs) (ROM Part3 V3.2) was released as a successor to Blu-ray, providing 4K video and HDR. Adoption is slow and is targeted toward a niche market for cinephiles.


Footnotes

Standards and specs



Other links


Author(s) : Æ Firestone

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