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 Level 2 Interchange: Level 3 Interchange: 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 Land – 1 data bit Pit – 0 data bit Channel bits: 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 CD-ROM 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

(not to be confused with children’s coloring books) 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