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What is Blu-ray?


Question: What is Blu-ray?
Answer: Blu-ray is one of the two major High Definition disc formats (the other being HD-DVD) that were vying to replace the current DVD standard in the U.S. and World market. As of February 19, 2008 HD-DVD was discontinued and Blu-ray is now the dominant high definition disc-based format.

Blu-ray vs DVD

Blu-ray builds on the foundation established by DVD in the quest for a high quality TV viewing and listening experience. Although DVD provides a very good viewing experience, it is not a high definition format. With advent of both HDTV and the trend for larger TV screen sizes and an increased use of video projectors, the limitations of DVD quality become more noticeable. Blu-ray enables the consumer to see more depth, a wider range of color shades, and more detail in the image than from DVD, providing a true high definition TV viewing experience from pre-recorded material on a disc-based medium similar to that of a DVD.

Where DVD utilizes Red Laser technology, the Blu-ray Disc format utilizes Blue Laser technology and sophisticated video compression to achieve high definition video playback on the same size disc as a standard DVD.

The significance of blue laser technology is that a blue laser is narrower than a red laser, which means that it can be focused more precisely onto a disc surface. Taking advantage of this, engineers were able to make the "pits" on the disc where information is stored smaller and, thus, fit more "pits" onto a blu-ray disc than can be placed on DVD. Increasing the number of pits creates more storage capacity on the disc, which is needed for the additional space required for recording high definition video.

In addition to increased capacity for video, Blu-ray also allows for more audio capacity than DVD. Instead of just including Standard Dolby Digital and DTS audio that we are familiar with on DVD (which are referred to as "lossy" audio formats because they are more highly compressed in order to fit onto a DVD disc), Blu-ray has the capacity to hold of up 8 channels of uncompressed audio in addition to a movie.

Overview of Blu-ray Disc Format Specifications

1. Disc Storage Capacity for Pre-recorded Playback Material (referred to as BD-ROM - Blu-ray Disc Read Only Memory): Single-layer (25GB) - Dual-layer (50GB)

2. Disc Storage Capacity for Home Recording (BD-R/BD-RE - BD-R stands for Blu-ray Disc Record Once, BD-RE stands for Blu-ray Disc Re-writable): Single-layer (25GB) - Dual-layer (50GB)

3. Data Transfer Rate: 36 to 48 MBPS (Megabits per Second) average - capable of up to 54 MPS - This exceeds the 19.3 Mbps transfer rate approved for HDTV broadcasting. This means that Blu-ray can not only handle a lot more information than DVD, but can also handle more information than HDTV television broadcasts are capable of.

4. Video Specifications: Compatible with full MPEG2 Encoding, as well as MPEG4 AVC (also know as H.264), and VC1 (based on the Microsoft WMV (Windows Media Video) format. Resolutions from 480i to 1080p (in either 2D or 3D) can be implemented at the content producer's discretion.

5. Audio Specifications: Only Dolby Digital, DTS, and Uncompressed PCM are required on all players. The following audio formats are optional - Dolby Digital Plus, Dolby TrueHD, DTS-HD Master Audio. However, almost all Blu-ray Disc players made since 2008 incorporate Dolby TrueHD/DTS-HD Master Audio on-board decoding, undecoded bitstream output, or both.

6. Internet/Network Connectivity: Although the Blu-ray format supports networking and internet capabilities (BD-Live), built-in networking and ethernet ports on individual Blu-ray Disc Players is only required on players made after November 2007. Some newer players also have a built-in WiFi connection option.

7. Manufacturing and Software Support: Blu-ray is now supported by all major manufacturers and movie studios including: Denon, Funai, Hitachi, LG, Matsushita (Panasonic), Onkyo, Pioneer, Philips, Samsung, Sharp, Sony, HP, Dell, Apple, TDK, Thomson, and Yamaha. Blu-ray is also now supported on the software side by Sony/Columbia, Twentieth Century Fox, Walt Disney Studios, MGM, Paramount, Dreamworks, Warner, and Universal, and others.

Also check out our About.com Video: What is Blu-ray?

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  8. What is Blu-ray? - How it Fits Into The Home Theater Experience.

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