by May 11, 2002 0 comments

Compact Disk Digital Audio
CD-DA or Compact Disc-Digital Audio was the first CD format defined in the original Red Book Specification released by Sony and Philips in 1981. The Red Book specifies a format for digital audio and also defines the specifications, such as the size of media, spacing of tracks, etc, for compact disks. The CD-DA format is used to create plain audio CDs that can even be played on standard CD players. A standard audio CD can store up to 74 minutes of audio. 

CD file systems
The one thing that’s common among most of these CD formats is the file system, called the ISO 9660. Originally, this format was used to store PC-compatible data, meaning it could not be read on a Mac machine. For Mac, HFS was the file system used. Later, however, this was changed to the Hybrid 9660 file system, which could take both Mac and PC compatible data, and the CD could therefore be read on both systems. Another limitation of the original ISO 9660 file system was that it only supported the 8.3 DOS file names, which became a problem when long file names were introduced in Windows 95. To overcome this, Joliet extensions were designed. This specification overcame the character set limitations to upper case characters, numbers and underscore, File Name Length limited to 8 characters plus three-character extension, Directory Tree, Depth limitations, and Directory Name Format limitations. Today, while burning CDs, you usually don’t have to specify the Joliet extensions manually, as the software by default accepts long file names.

CD-ROM Digital Data 
This is the most common standard for CD-ROMs (Compact Disk-Read Only Memory). The specifications for this format are defined in the Yellow Book, pioneered by Philips and Sony in 1983. The key objective behind this specification was to develop a format for CD-ROMs, such that any CD irrespective of its make can work on any CD-ROM drive. Much of the data you burn using a CD-Writer is done in this format. 

CD Text
The CD text is an audio CD format that can store up to 5000 characters of disc information, such as the title, artist, song titles, etc. This information is displayed when a disc is played on a CD text-enabled player. So if your CD player does not support this format, you’ll not be able to see this information. 

CD-ROM Extended Architecture 
CD-ROM XA(Extended Architecture) format came into existence to enhance the multimedia capabilities of CD-ROMs. The format was developed by Sony, Philips, and Microsoft and supports mixing of data with other types of formats. Thus on a CD-ROM XA disk you can store audio, data, compressed audio, video, compressed video, etc. To be able to read CD-ROM XA disks, your drive should support CD-ROM XA format. There are three formats based on CD-ROM XA: Photo CD, Video CD, and CD Extra.

CD Extra
Enhanced Music CDs, also known as CD Plus, is another extension of mixed-mode CDs developed by Philips and Sony in conjunction with other companies such as Microsoft and Apple. These are multi-session disks containing two sessions. CD Extra discs are playable on PCs, Macintosh computers, and dedicated CD Extra players. 

Photo CD
This format was developed by Kodak and Philips in the 90s and is used to store photographic images in a range of resolutions suitable for printing. If you have a photo CD-enabled software and drives you can read photo CD disc on your PCs. 

Video CD and Super VCD
Video CD, popularly known as VCD is used to store/record videos or movies on to CDs. They contain MPEG 1 audio and video for video applications and have a playtime of 74 mins. A super VCD on the other hand, contains MPEG 2 and has a playtime of 30-70 mins. You can play VCDs on either a VCD player or a VCD compatible drive.

Neelima Vaid

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