Compact Discs

1
Compact Discs
2
Track Characteristics
3
CDRom Bumps
4
CDRom Bumps etc.

• To read this information, the CD player passes a
  laser beam over the track. When the laser passes
  over a flat area in the track, the beam is
  reflected directly to an optical sensor on the
  laser assembly. The CD player interprets this as
  a 1. When the beam passes over a bump, the light
  is bounced away from the optical sensor. The CD
  player recognizes this as a 0.
• http//static.howstuffworks.com/flash/cd-read.swf

5
CD-R

• A CD-R doesn't have the same bumps and lands as a
  conventional CD. Instead, the disc has a dye
  layer underneath a smooth, reflective surface. On
  a blank CD-R disc, the dye layer is completely
  translucent, so all light reflects. The write
  laser darkens the spots where the bumps would be
  in a conventional CD, forming non-reflecting
  areas.
• http//static.howstuffworks.com/flash/cd-burner-cd
  r.swf

6
DVD The Basics
DVD is very similar to a CD, but it has a much
larger data capacity. A standard DVD holds about
? times more data than a CD does. This huge
capacity means that a DVD has enough room to
store a ? movie, as well as a lot of other
information.
7
The DVD Player
A DVD player is very similar to a CD player. It
has a laser assembly that shines the laser beam
onto the surface of the disc to read the pattern
of bumps. The DVD player decodes the MPEG-2
encoded movie, turning it into a standard
composite video signal. The player also decodes
the audio stream and sends it to a Dolby decoder,
where it is amplified and sent to the speakers.

8
DVD Media

• DVD-ROM can
• DVD-R can
• DVDR can
• DVDRW can

9
DVD Capacities
10
DVD Structure
11
The DVD Video Format
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. A group
called the Moving Picture Experts Group (MPEG)
establishes the standards for compressing moving
pictures

12
CODECs
A CODEC Audio and Video Codecs Lossy or
Lossless Codecs designed around content Sport
codec for ? Art codec for ? Audio Codecs Mobile
phones - ? Music ?

13
CODECs

• Multimedia codecs
• Both audio and video
• Need to be ?
• so 3rd channel contains ?
• 1000s of codecs
• Compatibility and obsolescence issues
• Not true of raw PCM data ?

14
CODECs
RealVideo RealNetworks RealMedia (.RM)
file Streaming video live TV WMV Windows
Media Video (competition to Real) Microsoft ?
applications Used in ?
technology DivX video codec Compress video
into relatively small file sizes Still maintains
visual quality Lossy MPEG-4 compression - used
for ripping

15
DVD/CD Feature
Fill with N/A, R or W/R in your own time
16
Blu-ray

• High density ? disc
• ? laser used to read/write - 405nm
• more on disc than ? laser 650nm
• 2-layer disc ?GB (6x DVD)
• Competition was HD DVD format
• 2/08 Toshiba withdrew HD DVD design
• Xbox 360 blu-ray?

17
Blu-ray

• Future?
• Quad-layer ( ?GB) demonstrated
• ? hours ?Mbit/s (HDTV) video
• ? hours video Cinema 4K format
• (4k horizontal pixel resolution 40962160)
• ?GB possible using ?, ?GB layers