DVD Technology The DVD Family G The Technologies

DVD - Technology

The DVD Family G The Technologies äDVD-ROM äDVD-RAM äDVD-R äDVD+RW äDVD-Audio äDVD-Video ähttp: //www. pctechguide. com/10 dvd. htm

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

DVD Technology G 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. G Differences between DVD and CD äTrack pitch: DVD = 0. 74 m v. CD = 1. 6 m äMinimum Pit Length: DVD= 0. 4 m v. CD = 0. 84 m

DVD Technology G DVD can hold anywhere from seven times to over 25 times the digital data on a CD G There are three reasons for DVD's greater data capacity: 1. Smaller pit size 2. Tighter track spacing 3. Multiple layer capability

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

DVD Technology (cont. ) G Data density of DVD is 4. 5 times CD ä Capacity of one-sided, single layer disc is 4. 7 GB ä Higher capacities can be achieved by using both sides of the disc and up to two layers per side: ÛSingle-sided, single-layer (4. 7 GB) – known as DVD-5 – The "5" in "DVD-5" signifies the nearly 5 GBytes worth of data capacity ÛSingle-sided, double-layer (8. 5 GB) – 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

DVD Technology ÛDouble-sided, single-layer (9. 4 GB) – Known as DVD-10, this construction features a capacity of 9. 4 GBytes of data. DVD-10 s 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 ÛDouble-sided, double-layer (17. 0 GB) – 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 doublesided DVD-9, where up to four hours of uninterrupted video and audio can be stored on one side Û 1 hour of MPEG-2 video = 2. 2 GB

DVD Technology (cont. ) G The technique for double-layering a DVD disc is of particular importance: äouter layer is semi-transparent [18 -30% reflectivity] äinner layer is more reflective [50 -80% reflectivity] äpickup lens is refocused to read desired layer äextra lead-out space required on inner layer ätwo methods of writing the layers ÛParallel track path (PTP) ÛOpposite track path (OTP) - allows near continuous read

Recordable DVD G Most common form is DVD-RAM äuses phase-change recording to provide rewriteable, erasable discs with 2. 6 GB per side capacity äphase-change uses a recording medium that can exist in both a crystalline and an amorphous state ärecording takes place by changing surface of disc to amorphous state, to represent the presence of data, by heating it with a laser

Recordable DVD G DVD-R äcompatible with DVD-ROM äinterchangeable with all other formats ätake-up slow, so drives are very expensive G DVD+RW änot adopted by DVD Forum as official standard äsimilar technique to DVD-RAM, 3 GB per side äactively supported by HP [drive], Philips & Sony

New Stuff G DVD-Audio äno audio standard in 1996 release äDVD-Audio 1. 0 standard approved by DVD Forum and released in March 1999 ärelease of products slowed by compliance with SDMI, uses Verance encryption & watermarking äDVD-Video players have better than CD sound

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