Transcript How does optical media technology work?

How Does Optical Media
Technology Work?
By Wayne He
Period 2
Common File Systems
for CDs and DVDs
High Sierra
 In
1985, representatives from several
companies met at High Sierra Hotel at
Lake Tahoe, Nevada.
 Created
a logical format and file structured
for CD-ROMs.
 Was
later submitted to the International
Organization for Standardization (ISO).
ISO 9660


Adapted from the High Sierra
format.
Level 1 Interchange:





Filenames may only have
uppercase letters, digits,
and underscores ( _ ).
8 characters max. for
filenames and 3 chars max
for extensions.
Directory names may only
have 8 characters
maximum.
Directories are limited to 8
levels deep.
Files must be contiguous.

Level 2 Interchange:


Allowed the filename
and extension to
have a total of 30
characters
maximum.
Level 3 Interchange:

“Files must be
contiguous”
restriction removed.
Joliet

Extension of ISO 9660
 CDs can be recorded with filenames with 64
characters max.
 Specifications:




Filenames and directories can have 64 characters
maximum (as stated above)
Directories may have extensions.
Directories can be deeper than eight levels.
Supports multisession recording.
Universal Disk Format (UDF)
 Allows
an operating system to read,
write, and modify data
 DVDs are based on this format.
Lands and Pits on CDs
and DVDs
 A land
is a layer that reflects light.
 Pits look like bumps.
Data Bits and Channel Bits
– 1 data bit
 Pit – 0 data bit
 Channel bits:
 Land
A
“1” refers to a
change from a land
to a pit, or from pit
to land.
 A “0” refers to no
change between a
land and a pit.
CLV and CAV
Circular Angular Velocity
 Accesses
data off
of rotating disks
 Used by disk
drives
 Disk motor does
not need to
change speed
Constant Linear Velocity

Used by older CDROM players
 Rotational speed
changes depending
on the data’s
location
 Ensures constant
data rate regardless
of the data’s location
Speeds of different optical
media technologies
Read/Write Audio
CD-ROM
CD-ROM
CD-i/XA
CD-i/XA
Mode 1
Mode 2
Form 1
Form 2
Speed
(CLV)
(2,352
(2,048
(2,336
(2,048
(2,324
Bytes/Block) Bytes/Block) Bytes/Block) Bytes/Block) Bytes/Block)
1x
176,000
153,600
175,200
153,600
174,300
2x
352,800
307,200
350,400
307,200
348,600
4x
705,600
614,400
700,800
614,400
697,200
6x
1,058,400
921,600
1,051,200
921,600
1,045,800
8x
1,411,200
1,228,800
1,401,600
1,228,800
1,394,400
12x
2,112,000
1,843,200
2,102,400
1,843,200
2,091,600
16x
2,816,000
2,457,600
2,803,200
2,457,600
2,788,800
20x
3,520,000
3,072,000
3,504,000
3,072,000
3,486,000
Color Books
(not to be confused with children’s coloring
books)
Red
 Red
books define CD-Audio
 “father” of all CD-formats
 Compact Disc-Digital Audio (CD-DA)
defined by Philips N.V. and Sony in
1980
Yellow
 “mother”
of all CD formats
 Defines CD-ROMs
 Developed by Philips N.V. and Sony in
1983
 Allows storing of digitalized content
Orange
 CD-Recordable
(CD-R)
 Created by Philips N.V. and Sony in
1988
 Can now record (as where the name
“CD-Recordable” came from)
Green
 Compact
Disc Interactive (CD-i)
 Stores an entire hardware and software
system
 Stores special compression methods for
audio and visual data
 Interleaves audio, video, and text data
Blue
 CD
Plus
 Multisession disc with two sessions
 Music
 Data
White
 Video
CD
 Developed by JVC, Philips, Sony, and
Matsushita in July 1993
 Stores MPEG-1 (Motion Picture Experts
Group) videos (maximum of 74 minutes)
 Playable on a personal computer (PC)
or a DVD player