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 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 size 2. Tighter track spacing 3. 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