Too Much Info about CDRRW

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Too Much Info about CDRRW

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CD-R Compact Disc Recordable, a write-once technology. One mistake and you've got a coaster. CD-RW Compact Disc Rewritable, can write and erase many times. ... – PowerPoint PPT presentation

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Title: Too Much Info about CDRRW

1
Too Much Info about CD-R/RW

A dramatic rendition by Bob Sulecki
18 February 2002

2
What is the difference?

CD-R Compact Disc Recordable, a write-once
technology. One mistake and youve got a coaster
CD-RW Compact Disc Rewritable, can write and
erase many times. Theoretically, a CD-RW disc
can be re-recorded 1000 times, some manufacturers
claim the number is closer to 100,000

3
CD-R, quick growth affordable
4
CD-RW speed format

Example 32 x 10 x 40
32 x write
10 x rewrite
40 x read
base speed is 150 KB/s

5
CD Recording Methods

Disc-at-once
Track-at-once

6
Disc-at-Once

Data written continuously until entire data set
is written
Advantage eliminates linking, run-in, and
run-out blocks
Disadvantage have to have all data ready now

7
Track-at-once

Allows a session to be written in a number of
discrete events (tracks)
Advantage can keep adding events until cd is
used up
Disadvantage each track has 150 blocks of
overhead for run-in, run-out, and linking
max. of 99 tracks per disc, track length min of
300 blocks (1 block 2KB)

8
Packet Write

Several write events are allowed within a track
Advantage less overhead. Where one track had
150 blocks of overhead, one packet has only 7
blocks reserved for overhead

9
Sessions

Multi-session
Open Session
Closed Session

10
Multi-Session

Can be complete by itself
Have the option of adding to later
Problem sometimes only first or last session
recognized

11
Open Session

Session not complete
can add to later
must finalize to make session complete

12
Closed Session

Session is complete
any session that has been fixated
fixation vs. finalization

13
Fixation vs. Finalization

Fixation-- writes the sessions lead-in and
lead-out information. Closes a session, it is
required before a cd can be used by cd-rom or
audio player
Finalization-- absolute lead-in/lead-out written,
drive told not to look for subsequent sessions.
No more information can be added to disc

14
Burning a CD-R

Reflective layer usually silvery alloy or 24-K
gold
Recording layer is dye
WORM (Write Once, Read Many)

15
CD-R burning

Laser heats up to critical temperature

16
CD-R burning

Laser heats up to critical temperature
Burns pits into organic dye in pre-formed grooves

17
CD-R burning

Laser heats up to critical temperature
Burns pits into organic dye in pre-formed grooves
Burned area becomes opaque due to chemical
reaction with heat

18
CD-R burning

Laser heats up to critical temperature
Burns pits into organic dye in pre-formed grooves
Burned area becomes opaque due to chemical
reaction with heat
Mimics the way light reflects off pits and lands
on conventional cd

19
CD-R care

Dyes in CD-Rs sensitive to UV light
Keep in protective case like standard cds
Results of mathematical models show the
information will last 70-200 years

20
CD-RW burning

Crystalline compound replaces dye in recording
layer of cd-r
Two dielectric layers to draw excess heat

21
CD-RW burning

Crystalline compound a mix of silver, indium,
antimony, and tellurium
phase change technique
When compound heated then cooled, it becomes
crystalline (good reflector)
Heated to higher temperature then cooled, becomes
amorphous (bad reflector)

22
3 laser powers

Write power (highest) creates amorphous state on
recording layer

23
3 laser powers

Write power (highest) creates amorphous state on
recording layer
Erase power (middle) melts the recording layer
and converts it to a reflective crystalline state

24
3 laser powers

Write power (highest) creates amorphous state on
recording layer
Erase power (middle) melts the recording layer
and converts it to a reflective crystalline state
Read power (lowest) does not alter the recording
layer, used for reading data

25
StandardsISO-9660

ISO 9660- covered recordable media
Was adopted in 1984
Set 99 track limit, specifies that data starts at
track time 000216
Inappropriate for DVD and CD-RW

26
UDF

Universal Disk Format replaced ISO-9660 in late
1990s
Compatible with DVD and CD-RW, and will be
revised to cover any future formats of discs
Enabled packet writing

27
Burnproof Technology