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DVD - Technology

DVD - Technology. The DVD Family. The Technologies DVD-ROM DVD-RAM DVD-R DVD+RW DVD-Audio DVD-Video http://www.pctechguide.com/10dvd.htm. DVD History. Originally two competing developments MMCD backed by Sony & Philips SD backed by Toshiba, Matsushita & Time Warner

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DVD - Technology

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  1. DVD - Technology

  2. The DVD Family • The Technologies • DVD-ROM • DVD-RAM • DVD-R • DVD+RW • DVD-Audio • DVD-Video • http://www.pctechguide.com/10dvd.htm

  3. DVD History • Originally two competing developments • MMCD backed by Sony & Philips • SD backed by Toshiba, Matsushita & Time Warner • 1995 - group of computer companies led by IBM insisted on single standard • 1997 - DVD Forum created • International standards developed by ECMA

  4. DVD Technology • Like CDs, DVDs use a track of pits signifying binary information on a disc, which is read by an optical pickup. DVD has the same dimensions as CD, but a much higher capacity and data transfer rate. • Differences between DVD and CD • Track pitch: DVD = 0.74m v. CD = 1.6m • Minimum Pit Length: DVD= 0.4m v. CD = 0.84m

  5. DVD Technology • DVD  can hold anywhere from seven times to over 25 times the digital data on a CD • There are three reasons for DVD's greater data capacity:1. Smaller pit size2. Tighter track spacing3. Multiple layer capability

  6. DVD Technology A comparison of a CD's pit size and track spacing vs. that of a DVD

  7. DVD Technology (cont.) • Data density of DVD is 4.5 times CD • Capacity of one-sided, single layer disc is 4.7GB • Higher capacities can be achieved by using both sides of the disc and up to two layers per side: • Single-sided, single-layer (4.7 GB) • known as DVD-5 • The "5" in "DVD-5" signifies the nearly 5 GBytes worth of data capacity • Single-sided, double-layer (8.5GB) • DVD-9 • the DVD player automatically switches to the second layer in a fraction of a second, by re-focusing the laser pickup on the deeper second layer.  This capability allows for uninterrupted playback of long movies up to four hours

  8. DVD Technology • Double-sided, single-layer (9.4GB) • Known as DVD-10, this construction features a capacity of 9.4 GBytes of data.  DVD-10s are commonly used to put a widescreen version of the movie on one side, and a full frame version of the same movie on the other side • Double-sided, double-layer (17.0GB) • The DVD-18 construction can hold approximately 17 GBytes (almost 26 times the data capacity of a CD), or about 8 hours of video and audio as a DVD-Video.  Think of DVD-18 as a double-sided DVD-9, where up to four hours of uninterrupted video and audio can be stored on one side • 1 hour of MPEG-2 video = 2.2 GB

  9. DVD Technology (cont.) • The technique for double-layering a DVD disc is of particular importance: • outer layer is semi-transparent [18-30% reflectivity] • inner layer is more reflective [50-80% reflectivity] • pickup lens is refocused to read desired layer • extra lead-out space required on inner layer • two methods of writing the layers • Parallel track path (PTP) • Opposite track path (OTP) - allows near continuous read

  10. Recordable DVD • Most common form is DVD-RAM • uses phase-change recording to provide rewriteable, erasable discs with 2.6GB per side capacity • phase-change uses a recording medium that can exist in both a crystalline and an amorphous state • recording takes place by changing surface of disc to amorphous state, to represent the presence of data, by heating it with a laser

  11. Recordable DVD • DVD-R • compatible with DVD-ROM • interchangeable with all other formats • take-up slow, so drives are very expensive • DVD+RW • not adopted by DVD Forum as official standard • similar technique to DVD-RAM, 3GB per side • actively supported by HP [drive], Philips & Sony

  12. New Stuff • DVD-Audio • no audio standard in 1996 release • DVD-Audio 1.0 standard approved by DVD Forum and released in March 1999 • release of products slowed by compliance with SDMI, uses Verance encryption & watermarking • DVD-Video players have better than CD sound

  13. New Stuff (cont.) • Universal players will not be available for some time, so DVD-Audio discs will not necessarily play on existing DVD-Video players • Sony & Philips have developed a competing format, Super Audio CD (SACD) • provides a two layer approach, one for existing CD players plus one for high-density DVD-Audio • extremely expensive!! • Incompatibility between DVD-Audio, DVD-Video and DVD-ROM remains a problem

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