DVD Technology

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DVD - Technology
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The DVD Family

• The Technologies
• DVD-ROM
• DVD-RAM
• DVD-R
• DVDRW
• DVD-Audio
• DVD-Video
• http//www.pctechguide.com/10dvd.htm

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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

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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

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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
  capacity1. Smaller pit size2. Tighter track
  spacing3. Multiple layer capability

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

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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

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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

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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

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Recordable DVD

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

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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

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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