design of mechatronics

1. CD and DVD technology
Presented By:
Steve Mathieu
Aaron Rinaca
Mike Ferris
Mike Burker

2. Brief History of Compact Digital
Media
1980: The firstCompact Disk player is produced by Sony/Phillips.
1982: The first Compact Disk is manufactured for sale, Billy Joel’s “52nd
Street”
1984: First portable Compact Disk players enter the market followed by car CD players shortly after.
1985: Sony/Philips announce the standard for compact disc storage of computer data, the CD-ROM
1987: Video CD format is designed.
1991: CD-R (Compact Disk Recordable) technology is introduced as a new storage technology.
1996: Digital Versatile Disk(DVD) technology is introduced
1997: DVD’s and DVD players begin to enter the market
1998: DVD Recordable systems invented and begin to enter the market
2000: DVD movies become mainstream and replace analog VHS as the format of choice.

3. Compact Disk (CD) Basics
•Uses Digital Technology to store data in binary values of Zero and One
•Uses “Pits” and “Lands” to signify binary values
•CD’s Read at a Constant Linear Velocity (CLV)
•Capable of Storing Large Amounts of Data (up to 700MB)
•Uses Error Correction for reliable data retrieval even if the CD becomes
lightly scratched.

4. Types Of Compact Disks
CD Audio – The first type of CD that was available. This allows for
the storage of digital audio. These are playable in all current CD
drives and car audio systems including DVD players.
CD-ROM – Computer Data is stored on these units such as games,
applications, and other files. Only readable on computers.
CD-R – Allows users to write data once to a recordable Compact
Disk. Can not be re-written and can be read in all current players
depending on wither the disk holds Audio or Data.
CD-RW – Users Can Write and Re-Write these special disks.
However because of the disk format, they cannot be read in Audio CD
players or DVD players.

5. CD Basic Technology Principles
P r i n t e d L a b e l
P r o t e c t i v e L a c q u e r
A l u m i n u m L a y e r
P o l y c a r b o n a t e
This diagram shows the side view of a common CD.
Printed Label : The image on the top of the CD, more of a “secondary” protection device than
anything else.
Protective Lacquer: This protects the CD from scratches and helps reflect the CD player’s laser.
Aluminum Layer: This is the reflective layer that primarily bounces the CD player’s laser back.
Polycarbonate: Known industry wide as a very durable substance, Polycarbonate is a clear covering
designed to protect the pits and lands in the CD surface.

6. CD Audio: How Does It Work?
Sound is Sampled at 40,000 Times per Second or Higher
Each Sample Must be Represented by at least a 16-bit number
Therefore, with 40,000 samples per second, and 16-bits per sample,
that’s over 640,000 bits per second! Therefore a 1 minute long
music clip would take over 38,400,000 bits (+/- 38MB) for storage!

7. Computer CD-ROM’s
Divided Into Sectors Containing User Data and Error Correction Codes.
Set up similar to hard drives however they do not have a “FAT” sector,
instead sectors are opened and closed with special pit and land
combinations.
File Systems are used to store data for easy and quick access

8. CD Recordable Basics
P r i n t e d L a b e l
P r o t e c t i v e L a y e r
R e f l e c t i v e G o l d L a y e r
D y e L a y e r
P o l y c a r b o n a t e
D a r k S p o t = P i t
This diagram shows the side view of a common CD.
Printed Label : The image on the top of the CD, more of a “secondary” protection device than anything else.
Protective Lacquer: This protects the CD from scratches and helps reflect the CD player’s laser.
Gold Layer: This is the reflective layer that primarily bounces the CD player’s laser back.
Dye Layer: This is burned into Dark or Light spots by the CD Recorder drive. Imitates lands and pits.
Polycarbonate: Known industry wide as a very durable substance, Polycarbonate is a clear covering
designed to protect the pits and lands in the CD surface.

9. CD-R Technology
Can Only Write Data Once
Uses Gold Instead of Aluminum for its Reflective Layer, thus a
higher cost than traditional CD’s
Uses Dye to “trick” the CD player Laser into thinking it is passing
over real Pits and Lands, when in actuality it is merely passing
over light and dark spots in the dye.

10. CD-RW Technology
Allows Users to Write Many Times (However This is Limited)
Uses Alloy of Sliver, Indium, Antimony, and Tellurium for Reflective Layer
Uses varying power levels to read and write lands and pits.
High Power = Creates Pits
Melts Alloy and Converts it to a High-reflectivity Crystalline state
Medium Power = Creates Lands
Melts Alloy and Converts it to Natural Crystalline state
Low Power = For Reading…no change to CD surface.
No Change in Alloy

11. Error Correction, Why Bother?
Error correction is an imperative part of CD technology, you
cannot take good enough care of a CD to prevent errors. Sony and
Phillips knew this, so they instituted the basics of Error Correction
Technology.
Errors can be caused by:
Manufacturing defects (Rare)
Scratches (Very Common)
Error Correction Types:
CIRC – (Cross Interleaved Read-Solomon Code) encoder
EFM Modulation – (Eight to Fourteen)

12. CIRC Error Correction:
Can correct Error Bursts up to 3,500 bits long (2.4mm in length)
Helps to compensate for Error Bursts up to 12,000 bits (8.5mm).
These types of errors are typically caused by minor scratches.

13. EFM Error Correction
Technology
Works to ensure Pits and Land Lengths are no Less Than 3 channel
bits and no More Than 11 Channel Bits
Very widely used in portable CD players because it helps to reduce
the skipping effect of jitter and distortions.

14. DVD is Born!
If CD is so great…why change it? Space limitations plagued
CD’s to a life only in the music market, Video producers could
not fit full length movies on a CD.
•The goal of DVD was to create a “vastly increased capacity,
with the ability to feature an entire movie in high-quality
digital video on a single side of a disc.”
•They also wanted...Brighter colors, sharper pictures, and
outstanding audio quality
•The goal was a 4.7 gigabyte capacity with the ability to hold
hours of full motion video and sound

15. Obviously they did it…but how?
• DVD uses Smaller pit
and land dimensions,
therefore the laser
must me exponentially
more accurate than
with CD’s.
• More closely-spaced
tracks, called "track
pitch"
• A shorter-wavelength
laser

16. The Wavelength Issue:
•DVD Players and DVD-ROM drives use a laser that
emits high intensity red light at 650 and 635nm vs the
780 nanometers for CD technology
•These shorter wavelengths are better at reading the
smaller, densely packed together pits and lands.
•The laser assembly has been re-engineered to produce a
more tightly focused laser beam

17. How Many Layers Would You
Like?
As an interesting consequence of using the new lasers and the
new DVD design elements, they found that multiple sides and
layers could be stacked onto a single DVD disk. A total of 4
configurations were found to be viable:
Single Side, Single Layer
Single Side, Dual Layer
Double Side, Single Layer
Double Side, Dual Layer

18. Single Side, Single Layer DVD
• Accounts for most DVD’s
• 4.7 GB of data capacity
• "7 times" the data capacity
of today’s music CDs and
CD-ROMs

19. Single Side, Dual Layer DVD
• 8.5 GB on one side
• additional 3.8 GB on the
second layer
• more than "13 times" the
capacity of today’s music
CDs and CD-ROMs

20. Dual Side, Single Layer DVD
• 9.4 GB (4.7 on each side)
• provides a little more
capacity
• Flipping the disc or
having a DVD Player
capable of two-sided
playback is required

21. Dual Side, Dual Layer DVD
• Maximum capacity of
17GB (8.5GB on each
side)
• Flipping the disc or
having a DVD Player
capable of two-sided
playback is required

22. CD versus DVD
Grudge Match of the Century!
Who has the advantage here?
Both discs are the same physical size (120 mm diameter & 1.2 mm thickness, which makes CDs compatible
with DVD players.
Both discs are made with the same basic technology and production processes
Both technologies read discs in the same manner
DVD software can be replicated from existing CD production facilities
However DVD has some tricks up its sleeves….
DVD can hold exponentially more data than a CD can
DVD has Higher density data storage where smaller pits and smaller tracks in DVDs provide seven times
storage alone compared to CDs
DVD has less overhead & more area because the DVD’s error-correction scheme is more efficient and
requires less storage space that can be used for other information
DVD can have Multi-layer storage whereas CD stores data on one layer on one side of disc. DVD can store
up to two layers on up to two sides of the disc, which allows up to 4X the storage amount

23. Side By Side Comparison:
Specification CD DVD
Disc Diameter 120 mm 120 mm
Disc Thickness 1.2 mm 1.2 mm
Disc Structure Single substrate Two bonded .6 mm substrates
Laser Wavelength 780 nm (infrared) 635 or 650 nm (red)
Numerical Aperture .45 .6
Track Pitch 1600 nm 740 nm
Shortest Pit Length 830 nm 400 nm
Reference Speed 1.2 m/sec CLV 4.0 m/sec CLV
Data Layers 1 2
Data Sides 1 2
Data Capacity 650 MB 4.7 – 17.0 GB
User Data Rate 1.4 Mbps (Video-CD) 10.0 Mbps (DVD-Video)
Readout Wavelength 780 nm 650 nm
Scanning Speed 1.2 – 1.4 m/s 3.49 – 3.84 m/s
Reflectivity 70% minimum 45 – 85%
Modulation 8/14 8/16
Error Correction CIRC RS-PC
Error Correction Overhead 23/34% 13%
Format overhead 252% 136%

24. Could DVD replace CD Audio?
Simply Put…why SHOULDN’T IT? After all….
CDs can hold only 80 minutes of music, while DVDs can hold 7 hours of music at the same quality, or 80
minutes of music at better quality
DVD can record audio at better quality than CD because of increased sampling rate and quantization levels
DVD can record in surround sound (6 channels instead of 2)
DVD audio requires a player with a 192kHz/24-bit DAC
DVD drives can play CD audio so it is downwardly compatible technology. Unfortunately, CD drives cannot play
DVD audio
Specification CD Audio DVD Audio
Sampling rate 44.1kHz 192 kHz
Samples per second 44,100 192,000
Sampling Accuracy 16-bit 24-bit
Number of Possible
Output Levels
65,536 16,777,216

25. DVD to surpass CD Video and
VHS?
•DVD video is encoded in MPEG-2 format, while CD video is
encoded in MPEG-1 format
•CD data capacity limitations make competing with DVD video in
resolution and duration impossible
•DVD movies exceed VHS quality, while CD movies cannot match
VHS quality
•DVD drives can play CD video, but CD drives cannot play DVD
video

26. Is CD technology on the way
out?
•CDs will continue to be a leading audio format in the recording industry for several
years to come
•Recordable CDs will serve as excellent form of file storage
•More advanced applications will abandon the CD format, while smaller applications
may stay will the CD format
•Newer players and drives that support new formats, yet providing backwards
compatibility will prolong the CD format’s life
•Video games systems will move away from the CD format towards DVD, for example
the new Sony Playstation 2 uses DVD technology as does the upcoming Microsoft X-
BOX and the next generation Nintendo system.

27. The future of DVD
•DVD Video will become the leading format for the movie industry
•DVD-ROMs will become the mainstream for computer applications
•DVD will become the leading format for video game systems
•Recordable DVD will eventually be available to consumers
•Software projects containing a large amount of multimedia will take advantage
of DVD’s high storage capacity
•DVD Audio will compete with the currently experimental Super Audio CD
(SACD) technology.

28. The End