Blu Ray FAQ

General

1.1 What is Blu-ray?
1.2 Why the name Blu-ray?
1.3 Who developed Blu-ray?
1.4 What Blu-ray formats are planned?
1.5 How much data can you fit on a Blu-ray disc?
1.6 How much video can you fit on a Blu-ray disc?
1.7 How fast can you read/write data on a Blu-ray disc?
1.8 What video codecs will Blu-ray support?
1.9 What audio codecs will Blu-ray support?
1.10 Will Blu-ray discs require a cartridge?
1.11 Will Blu-ray require an Internet connection?
1.12 Will Blu-ray down-convert analog outputs?
1.13 Will Blu-ray support mandatory managed copy?
1.14 When will I be able to buy Blu-ray products?
1.15 What will Blu-ray products cost?

Blu-ray vs DVD

2.1 Will Blu-ray replace DVDs?
2.2 Will Blu-ray be backwards compatible with DVD?
2.3 Why should I upgrade from DVD to Blu-ray?
2.4 What is the difference between Blu-ray and DV?
2.5 Will Blu-ray replace VCRs?
2.6 What about Blu-ray for PCs?

Blu-ray vs HD-DVD


3.1
 Is Blu-ray the same thing as HD-DVD?
3.2 What benefits does Blu-ray offer compared to HD-DVD?

General

1.1 What is Blu-ray?

Blu-ray is the name of a next-generation optical disc format. The format was developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data. This format and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc.

1.2 Why the name Blu-ray?

The name Blu-ray utilizes a blue-violet laser to read and write data. The name is a combination of “Blue” (blue-violet laser) and “Ray” (optical ray). According to the Blu-ray Disc Association, the absence of “e” in the spelling of “Blu-ray” is not a mistake, it was intentionally left out so the term could be registered as a trademark.

1.3 Who developed Blu-ray?

The Blu-ray Disc format was developed by the Blu-ray Disc Association (BDA), a group of leading consumer electronics, personal computer and media manufacturers, with more than 180 member companies from all over the world. The Board of Directors currently consists of:

Apple Computer, Inc.
Dell Inc.
Hewlett Packard Company
Hitachi, Ltd.
LG Electronics Inc.
Matsushita Electric Industrial Co., Ltd.
Mitsubishi Electric Corporation
Pioneer Corporation
Royal Philips Electronics
Samsung Electronics Co., Ltd.
Sharp Corporation
Sony Corporation
Sun Microsystems, Inc.
TDK Corporation
Thomson Multimedia
Twentieth Century Fox
Walt Disney Pictures
Warner Bros. Entertainment

1.4 What Blu-ray formats are planned?

As with older formats, Blu-ray plans to provide a wide range of formats including record able formats. 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.

1.5 How much data can you 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 expandable, it also includes support for multiple layers. This should allow the storage capacity to be doubled or tripled in the future simply by adding more layers to the discs.

1.6 How much video can you fit on a Blu-ray disc?

Over 9 hours of high-definition (HD) video on a 50GB disc.
About 23 hours of standard-definition (SD) video on a 50GB disc.

1.7 How fast can you read/write data on a Blu-ray disc?

According to the Blu-ray Disc specification, 1x speed is defined as 36Mbps. However, as BD-ROM movies will require a 54Mbps data transfer rate the minimum speed we’re expecting to see is 2x (72Mbps). Blu-ray also has the potential for much higher speeds, as a result of the larger numerical aperture (NA) adopted by Blu-ray Disc. The large NA value means that Blu-ray will require less recording power and lower disc rotation speed other formats to achieve the same data transfer rate. While the media itself limited the recording speed in the past, the only limiting factor for Blu-ray is the capacity of the hardware. If we assume a maximum disc rotation speed of 10,000 RPM, then 12x at the outer diameter should be possible (about 400Mbps). This is why the Blu-ray Disc Association already has plans to raise the speed to 8x (288Mbps) or more in the near future.

1.8 What video codecs will 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.

It will be up to content creators to decide which codecs to use. All Blu-ray players will be able to decode any of these codecs.

1.9 What audio codecs will 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)

Not all of the Blu-ray players will be able to decode these audio codecs. Some higher definition audio will not be decoded by some models. However, most high end receivers should be able to decode the higher definition audios. Check with the model specification for proper audio decoding.

1.10 Will Blu-ray discs require a cartridge?

No, the development of new low cost hard-coating technologies has made the cartridge obsolete. Blu-ray will rely on hard-coating for protection, which will make the discs even more resistant to scratches and fingerprints than older formats.

1.11 Will Blu-ray require an Internet connection?

No, you will not need an Internet connection for basic playback of Blu-ray movies. However, the Internet connection can provide extra bonus materials. Blu-ray players with profile 2.0 will be web enabled. Previous profiles will be not be compatible with the web enabled Blu-ray discs.

1.12 Will Blu-ray down-convert analog outputs?

No, Blu-ray players will not down-convert the analog output signal unless the video contains something called an Image Constraint Token (ICT). This feature is not part of the Blu-ray Disc spec, but of the AACS copy-protection system also adopted by HD-DVD. It will be up to each movie studios to decide on the use of ICT. The good news is that Sony, Disney, Fox, Paramount, MGM and Universal have already stated that they have no intention of using this feature. The other studios will most likely follow Sony, Disney, Fox, Paramount, MGM, and Universal.

1.13 Will Blu-ray support mandatory managed copy?

Yes, mandatory managed copy (MMC) will be part of the Blu-ray format. This feature will enable consumers to make legal copies of their Blu-ray movies that can be transferred over a home network. This does not mean the disc will allow uncontrolled copying.

1.14 When will I be able to buy Blu-ray products?

Blu-ray products are available right now. Newer Blu-ray players supporting profile 2.0 should be rolling out as we speak.

1.15 What will Blu-ray products cost?

The cost varies with the manufacturer and the features on the players itself. The manufacturing costs have come down since the launch of Blu-ray players. The new models with profile 2.0 will be more expensive than the older models. Also, the level of audio decoding done on the player can increase the overall price. The typical Blu-ray players can cost anywhere between $300 to well over $1,000.

According to the Blu-ray Disc Association, the overall cost of manufacturing Blu-ray Disc media will in the end be no more expensive than producing a DVD. The reduced injection molding costs (one molding machine instead of two, no birefringence problems) offset the additional cost of applying the cover layer and low cost hard-coat, while the techniques used for applying the recording layer remain the same. As production volumes increase the production costs should fall and eventually be comparable to DVDs.

Blu-ray vs DVD

2.1 Will Blu-ray replace DVDs?

Yes. The Blu-ray format has received broad support from the major movie studios as a successor to today’s DVD format. In fact, seven of the eight major movie studios (Disney, Fox, Warner, Paramount, Sony, Lionsgate and MGM) have released titles in the Blu-ray format. Also, with the withdraw of HD-DVD from the “format war,” Blu-ray has been crowned as the successor to the current DVD format. Many studios have also announced that they will begin releasing new feature films on Blu-ray Disc day-and-date with DVD.

2.2 Will Blu-ray be backwards compatible with DVD?

Yes. All of the current Blu-ray players and future models will be able to read and upconvert current DVD formats. Most of the Blu-ray players coming out will support upscaling of DVDs to 1080p/1080i, so your existing DVD collection will look even better than before. While it’s up to each manufacturer to decide if they want to make their products backwards compatible with DVD, the format is far too popular to not be supported. The Blu-ray Disc Association (BDA) expects every Blu-ray Disc device to be backward compatible with DVDs.

2.3 Why should I upgrade from DVD to Blu-ray?

The simple answer is HDTV. If you’ve ever seen high-definition (HD) video on an HDTV, then you know just how incredibly sharp the picture is and how vivid the colors are. In fact, HD offers five times the amount of detail compared to standard-definition (SD). The problem with today’s DVDs is that they only support SD and don’t have the necessary storage capacity to satisfy the needs of HD. That’s where Blu-ray comes in, it offers up to 50GB of storage capacity and enables playback, recording and rewriting of HD in all of the HD resolutions including 1080p. The format also supports high-definition audio formats and lossless audio.

In addition to the greater video and audio quality, the extra storage capacity also means there will be plenty of room for additional content and special features. This combined with the new BD-J interactivity layer adopted by Blu-ray will bring the menus, graphics and special features to a whole new level. For example, you will be able to bring up the menu system as an overlay without stopping the movie, and you could have the director of the movie on the screen explaining the shooting of a scene while the scene is playing in the background. The advanced interactivity combined with the networking features of Blu-ray will also allow content producers to support new innovative features such as downloading extras, updating content via the web, and watching live broadcasts of special events.

Thanks to the greatly enhanced HD video and audio quality as well as the advanced interactivity and networking features, Blu-ray represents a huge leap forward in the DVD viewing experience and will offer consumers an unprecedented HD experience.

2.4 What is the difference between Blu-ray and DVD?

Parameters
Blu-ray
DVD
Storage capacity 25GB (single-layer)50GB (dual-layer) 4.7GB (single-layer)8.5GB (dual-layer)
Laser wavelength 405nm (blue laser) 650nm (red laser)
Numerical aperture (NA) 0.85 0.60
Disc diameterDisc thickness 120mm
1.2mm
120mm1.2mm
Protection layerHard coating 0.1mm
Yes
0.6mmNo
Track pitch 0.32µm 0.74µm
Data transfer rate (data)
Data transfer rate (video/audio)
36.0Mbps (1x)54.0Mbps (1.5x) 11.08Mbps (1x)10.08Mbps (<1x)
Video resolution (max)
Video bit rate (max)
1920×1080 (1080p)40.0Mbps 720×480/720×576 (480i/576i)9.8Mbps
Video codecs MPEG-2MPEG-4 AVC

SMPTE VC-1

MPEG-2
Audio codecs Linear PCMDolby Digital

Dolby Digital Plus

Dolby TrueHD

DTS Digital Surround
DTS-HD

Linear PCMDolby Digital

DTS Digital Surround


Interactivity BD-J DVD-Video

2.5 Will Blu-ray replace VCRs?

Blu-ray recorders combined with hard drives can record High definition contents from television. Although the latest DVR can record HDTV contents, the sheer size of the files can overwhelm the built in hard drives. The Blu-ray recorder can alleviate this problem by archiving the files on the disc itself. With the storage capacity of 25-200 GB, Blu-ray is ideal storage medium for high definition contents. The Blu-ray recorders will also offer a lot of compelling new features not possible with a traditional VCR:

# Random access – instantly jump to any place on the disc
# Searching – quickly browse and preview recorded programs in real-time
# Create playlists – change the order of recorded programs and edit recorded video
# Simultaneous recording and playback of video (enables Time slip/Chasing playback)
# Automatically find an empty space to avoid recording over programs
# Improved picture – ability to record high-definition television (HDTV)
# Improved sound – ability to record surround sound (Dolby Digital, DTS, etc)

2.6 What about Blu-ray for PCs?

BD-ROM (read-only), BD-R (recordable) and BD-RE (rewritable) drives are already available for PCs.

Blu-ray vs HD-DVD

3.1 Is Blu-ray the same thing as HD-DVD?

No, HD-DVD was the name of a competing next-generation optical disc format developed by Toshiba and NEC. Toshiba has recently announce the discontinuation of HD-DVD support and development

3.2 What benefits does Blu-ray offer compared to HD-DVD?>

Although both Blu-ray and HD-DVD are similar in many aspects, there are some important differences between them.

The first is capacity. Because Blu-ray utilizes a lens with a greater numerical aperture (NA) than HD-DVD, the laser spot can be focused with greater precision to fit more data on the same size disc. Blu-ray can store up to 25 GB on single layer compared to 15 GB for HD-DVD

The second is content. The Blu-ray has garnered more support from movie studios. With the demise of HD-DVD, all of the movie studios have pledged their support for the Blu-ray platform.

Check out our Glossary section!

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