Audio CD is an umbrella term that refers to many standards of means of playing back audio on a CD.
It may specifically refer to:
Standards
- Compact Disc, an optical disc used to store digital data
- Red Book (CD standard), the original means of playing back audio on the medium
- 5.1 Music Disc, an extension to the red book standard that uses DTS Coherent Acoustics 5.1 surround sound
- Super Audio CD, a format which competes with DVD-Audio
- MP3 CD, a disc that contains MP3 files in Yellow Book format rather than converted from MP3 to Red Book format
MP3 CD
An MP3 CD is a Compact Disc (usually a CD-R or CD-RW) that contains digital audio in the MP3 file format. Discs are written in theYellow Book standard data format (used for CD-ROMs), as opposed to the Red Book standard audio format (used for audio CDs).
MP3 files are supported by many modern CD players, including DVD players. In addition, some CD players are also capable of playing other formats, such as Ogg Vorbis and the proprietary Windows Media Audio and ATRAC.
Because of audio data compression, an MP3 CD does not have to spin all of the time, potentially saving battery power, however, decompressing the audio takes more processor time. The song is buffered in random-access memory, which also provides protection againstskipping.
The number of songs that a disc can hold depends on how the songs are encoded and the length of the songs. A standard audio CD (74 minutes) can hold about 18 songs, a 650-MB data CD (equivalent to 74-minute audio CD) containing mid-quality (160-kb/s) audio files can hold approximately 9.5 hours of music or about 138 songs.
ID3 tags stored in MP3 files can be displayed by some players, and some players can search for MP3 files within directories on an MP3 CD. The sound quality of an MP3 CD may be inferior to that of an audio CD, because MP3 compression is lossy.
There is no official standard for how the MP3 files on an MP3 CD are stored on discs. As such, the format expected by different players varies. This sometimes leads to incompatibilities and difficulty in playing discs, often because of filename length limits, sub-directory limits, number of files limits, and special character bugs.
Data CD
A data CD is a compact disk formatted to store files. The types of files typically stored on a data CD might include compressed zip files, word processing documents, spreadsheets, text files, graphics, QuickTime-style movie files, or MP3 music files.
A single data CD typically offers 680-700 megabytes (MB) of storage, providing a respectable chunk of space for building backups of everything from your MP3 libraries to your favorite programs. A data CD is also handy for storing sensitive files that are better kept off the computer’s hard drive where they could become subject to key loggers, snooping or virus corruption. This might include financial records, business records, tax or investment files, and so on.
Aside from archiving, a data CD can also be used to easily transfer large quantities of data, presentations or programs to another computer. A virtual supersized disk, the data CD is highly portable and fairly indestructible given a modicum of care in handling. Just four CDs provides over 2.5 gigabytes of storage power, making the data CD a convenient tool.
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