Why Wont This DVD Play

1
Why Wont This DVD Play ?

• LIBR 181
• Audiovisual Services Spring 2005
• Dette Peach-Atkins

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Why wont this DVD play in my player at home?

• There is no simple answer
• This is a common question heard at the library
  circulation desk in Richland.
• The simple answer is that not all DVDs are
  compatible in all DVD players.

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• DVDs first came to the market in 1997 and have
  taken home movie viewing by storm. More than 21
  million DVD players were sold in 2003 alone.
• The DVD which once stood for digital video disc
  became digital versatile disc. Many now say it
  no longer stands for anything but the convenient
  disc shape.

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• The DVD has better picture quality and sound
  (surround) plus so many other features video
  tapes cant compete.
• Unfortunately, the specifications of this media
  are not as clear as the picture it provides.
  There are numerous, non-compatible, often
  conflicting formats currently in use.

5
Not all DVDs are created equally

• A DVD is composed of several layers of plastic,
  totaling about 1.2 millimeters thick. Each layer
  is created by injection molding polycarbonate
  plastic. This process forms a disc that has
  microscopic bumps arranged as a single,
  continuous and extremely long spiral track of
  data.

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How A DVD IS Made

• Once the clear pieces of polycarbonate are
  formed, a thin reflective layer is sputtered
  onto the disc covering the bumps. Aluminum is
  used behind the inner layers, but a
  semi-reflective gold layer is used for the outer
  layers, allowing the laser to focus through the
  outer and onto the inner layers. After all the
  layers are made, each one is coated with lacquer,
  squeezed together and cured under infrared light.
  For single-sided discs, the label is
  silk-screened onto the non readable side.

7
Storage Capacity of a DVD

• A single-sided, single layer disc is about 4.7 GB
  which is about seven times as much data as a CD.
  Even though its storage capacity is huge, the
  uncompressed video data of a full-length movie
  would never fit on a DVD. In order to fit a
  movie on a DVD, you need video compression.

8
Moving Picture Experts Group

• A group called the Moving Picture Experts Group
  (MPEG) establishes the standards for compressing
  moving pictures. When movies are put onto DVDs,
  they are encoded in MPEG-2 format. This is an
  accepted international standard. Your DVD player
  contains an MPEG-2 decoder, which can uncompress
  this data as quickly as you can watch it. If an
  average DVD movie were not uncompressed, it would
  take at least a year to download it.

9
The typical contents of a DVD movie

• The typical contents of a DVD movie are
• Up to 133 minutes of high-resolution video, in
  letterbox (which fits wide-screen TVs) or
  pan-and-scan, with 720 horizontal resolution.
• Soundtrack presented in up to eight languages
  using 5.1 channel Dolby digital surround sound.
• MPEG-2 Format American and Japanese television
  use a format called NTSC, which displays a total
  of 30 frames per second other countries use PAL
  format, which displays at 50 frames per second.

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Contents of A DVD Movie Continued

• Subtitles in up to 32 languages.
• Closed captioning
• Some DVDs carry commentary tracks, in which the
  filmmaker talks about the movie while it is
  running.
• Region codes are used by the movie industry for
  two reasons. The first reason is to stop
  unauthorized copying of the movie. The second is
  if the movie studio wants to release the movie at
  different times in different regions of he world.
  The actual region code is stored in one byte on
  the DVD. Each DVD player is hardware coded with
  one region. The U.S. code is region one.

11
DVD Compatibility

• Most DVD players manufactured in late 2001 to
  present are compliant with the complete DVD
  standards and will play any type of optical disc.
  Beginning in late 2002, DVD players now carry
  the DVD logo which has the (MULTI) for
  multi-format drives they will playback a variety
  of videos including DVD-R discs.

12
Compatibility continued

• Different brands of DVD media vary in their
  compatibility with home DVD players. Older DVD
  players and computers equipped with DVD drives
  may not be compatible for todays format.
• Some new DVD players and computers are very
  sensitive to the media or thickness on a disc.
  Other players will not play DVDs with laminated
  labels, or gold, green or purple surface media.

13
The DVD Player

• The fundamental job of the DVD player is to focus
  the laser on the track of bumps. The red laser
  beam passes through the polycarbonate layer,
  bounces off the reflective layer behind it and
  hits an opt-electronic device, which detects
  changes in light. The bumps reflect light
  differently than the flat areas of the disc, and
  the sensor detects that change in reflectivity.
  The hardest part of reading a DVD is keeping the
  laser beam centered on the data track.

14
The Tracking System

• The tracking system has to move the laser
  continually outward. As the laser moves outward
  from the center of the disc, the bumps move past
  the laser at an increasing speed as the laser
  moves outward. The spindle motor must slow the
  spinning of the DVD so that the bumps travel past
  the laser at a constant speed because the data
  must come off the disc at a constant rate.

15
Tracking Continued

• On single-layer DVDs the track always circles
  from the inside of the disc to the outside. The
  incredibly tiny data track is just 740 nanometers
  separate from one track to the next (a nanometer
  is a billionth of a meter). The elongated bumps
  that make up the track are each 320 nanometers
  wide, a minimum of 400 nanometers long and 120
  nanometers high.

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More On Tracking

• The pits on a DVD appear on the aluminum side,
  but the side the laser reads from are called the
  bumps.
• The microscopic dimensions of the bumps make the
  spiral track on a DVD extremely long. If you
  could lift off the data track on a single layer
  of DVD, and stretch it out into a straight line,
  it would be almost 7.5 miles long.

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DVD Players/Decks

• DVD players give you all sorts of control over
  the picture you watch. Many DVD movies have an
  on-screen index, where the creator of the DVD has
  labeled many significant parts of the movie.
• With your remote you can select
• Picture Zoom lets you zoom in on a specific
  frame.
• Black-level adjustment brings out the detail in
  dark parts of the screen image.
• Multi-angle capability If youve ever wanted to
  see certain action scenes from different angles.
  Up to nine
• Angles of the same scene can be placed in the DVD
  format.
• Chapter preview lets you scan until you find
  what you want a video can hold up to 99
  chapters.

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DVD Players Continued

• Go-to by time lets you enter how many hours
  and minutes into the disc youd like to skip to.
• Parental Control The DVD is the first video
  format that can actively change the content based
  on the movie rating. When a DVD is placed into a
  player, the rating level of the movie is mapped
  against the rating level in the player. A DVD
  player set to only play PG movies will
  automatically switch to a PG version of the
  movie. If an R-rated DVD does not have a PG
  variation of the move the player will not play
  the movie.

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Why are there new DVD formats in production?

• A high-definition movie, which has a much clearer
  image takes more bandwidth and therefore requires
  a disc with about five times more storage than
  those on the market now.
• TV sets and movie studios are moving to high
  definition, so a need for a DVD with a higher
  storage capacity is in development.
• Thats where HD-DVD and Blu-ray DVD come in.

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HD-DVD VS. Blu-ray

• HD-DVD, also called AOD (Advanced Optical Disc),
  was actually in the works before regular DVD, but
  didnt begin real development until 2003. It
  uses the same basic structure as a DVD but with
  enhanced storage capacity. Both HD-DVD and
  Blu-ray use a blue laser. A blue laser has a
  shorter wavelength than a red laser. The smaller
  beam focuses more precisely, enabling it to read
  information recorded in smaller pits. Both
  Blu-ray and HD-DVD read pits that are much
  smaller than the pits on a standard DVD. Smaller
  pits mean more storage space.
• Because HD-DVD uses the same basic format as the
  traditional DVD, it can be manufactured with the
  same equipment, saving on costs. The industry is
  planning to market backward-compatible drives
  with both blue and red lasers, which will be able
  to play traditional DVDs and CDs as well as
  Blu-ray discs.

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HD-DVD VS. Blu-ray Data Storage

• A single-layer, rewritable HD-DVD disc can hold
  20 GB thats just over an hour of HD-video or
  about 6 hours of standard video.
• A double-layer, rewritable HD-DVD can hold 32 GB
  thats about 2.5 hours of HD-video, and more
  than 13 hours of standard video.
• The disadvantage is that it cant match the
  storage space or the interactive capabilities of
  Blu-ray.

• A single-layer, rewritable Blu-ray disc, which is
  roughly the same size as a DVD, can hold up to 27
  GB of data-thats more than 2 hours of
  high-definition video or about 13 hours of
  standard video.
• A double layer, rewritable Blu-ray disc can
  store about 54 GB, enough to hold about 4.5 hours
  of HD-video or more than 20 hours of standard
  video.

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Which format to win has to do with who your
friends are

• HD-DVD has the DVD Forum behind it, as well as
  these movie studios
• New Line
• Paramount
• Universal
• Warner Bros.
• Microsofts new operating system (Longhorn)

• Blu-ray has Sony, JVC, Phillips, Pioneer,
  Panasonic,
• as well as movie studios
• Columbia Tri-Star
• Disney
• MGM
• PlayStation 3 game system

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Is my video library becoming coasters?

• HD-DVD and Blu-ray are the two major competitors,
  but there are HD-DVD 9 from Warner Bros., Forward
  Versatile Disc (FVD) from Taiwan, Enhanced Video
  Disc (EVD) from China and T3Pioneer. Pioneer is
  developing an optical disc that will hold 500 GB
  of data. It uses an ultraviolet laser which has
  an even shorter wavelength than blue. It will be
  interesting to see what happens by the end of
  this year or beginning of 2006.Thats when
  Blu-ray is expected to hit the market. It will be
  up to the consumer to decide the format for the
  future as far a price and ease of use.

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Sources

• http//hometheaterinfo.com/dvd_formats.htm
• http//electronics.howstuffworks.com/dvd.htm
• www.consumerreports.org/Specail/Advantgo/Electroni
  cs/dvd.htm
• Pictures from http//electronics.howstuffworks.com
  /dvd.htm