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Phillips and Sony developed the format
standard for audio CDs in the early 1980s. When manufacturers realized
the potential for using CDs to store information for computers, they
developed even more formats to ensure compatibility when recording
CDs. There are two major types of CD formats:
Logical Standards
A logical standard defines the way information is stored on the
media. CDs and other computer accessed discs use a series of
tracks and sectors (also called frames on CDs) to store the data
on the disc. Simply put, a CDs logical standard determines its
file system structure. Currently, ISO 9660 (also referred to as
the High Sierra Standard) is the industry standard format. CDs
created using the ISO 9660 format can be accessed by most
platforms and operating systems in existence today. Other formats
such as Rock Ridge (for UNIX), HFS (for Macs), and Hybrid HFS/ISO
do exist and are used today, but ISO 9660 is internationally
accepted as the standard. Two formats that improve upon ISO 9660
include JOLIET and UDF. JOLIET is the Microsoft version of ISO
9660 that extends the maximum characters in a filename from 8 to
64. Universal
Disc Format (UDF) is an emerging standard built upon ISO
9660 specifically designed for data storage.
Physical Standards
Physical standards define where the information is placed on a CD.
Most formats fall within the "Color Books". When
Phillips and Sony completed the format for the audio CD, the rules
were published in a book with a red cover. This format quickly
became known as the Red Book format and is the basis of all other
Color Book formats.
- Red Book – Also known as Compact Disc. Digital Audio
(CD-DA), this format defines an audio CD. It specifies how songs
are placed in tracks on the disc.
- Yellow Book – The Yellow Book was developed early on as
the initial format for data. This format allows for data to be
written as files instead of as streaming information.
- Green Book – In 1986, Phillips created the Green Book
format for its new CD-I (Interactive) discs. This format was
specially designed to synchronize audio and video data for
multimedia applications.
- Orange Book – The 1990 Orange Book standard defines the
physical format for recordable CDs. The standard is subdivided
into three parts. Part 1 deals with Magneto Optical
(MO) devices,
part 2 handles Write Once (WO) drives, and part 3 addresses re-writable
drives.
- White Book – This standard addresses the method of
recording MPEG1 audio, video, and still graphics to a Video CD (VCD).
These discs require a specialized player or software application
to access them as the information is compressed to a great degree.
- Blue Book – The Blue Book standard specifies the format
of Enhanced CDs (E-CD). Basically, E-CDs are stamped multisession
discs that feature Red Book audio and Yellow Book multimedia data
on a single disc.
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