(1) See also carrier detect and candela.
(2) (Compact Disc) An optical digital audio disc that contains up to 74 minutes of hi-fi stereo sound. Introduced in the U.S. in 1983, the disc is a plastic platter (120mm/4.75" diameter) recorded on one side, with individual tracks playable in any sequence. Its storage capacity is from 650MB to 700MB. Other forms of CDs, such as CD-ROM, CD-I and Video CD, all stem from the original Compact Disc-Digital Audio (CD-DA) format. CDs can be played in CD, CD-ROM, CD-R, CD-RW and most DVD drives. For more on how CDs are made, see CD-ROM.
Sound is converted into digital code by sampling the sound waves 44,056 times per second and converting each sample into a 16-bit number. It requires approximately 1.5 million bits of storage for each second of stereo sound. The audio tracks are recorded as microscopic pits in a groove that starts at the center of the disc and spirals outward to the edge.
A Note on Terminology
In the early 1990s when CD-ROMs first became popular, "CD" meant music, and "CD-ROM" meant data. Today, "CD" refers to both audio CDs and data CD-ROMs, which also include CD-R and CD-RW media. See CD-ROM.
The Books
Documentation for various CD formats are found in books commonly known by the color of their covers.
What Happened to the Phonograph?
The audio CD was introduced in the U.S. in 1983, and within five years, CDs and CD players exceeded the sales of LPs and turntables.
Carved Sound
Unlike phonograph records, in which the platter is literally carved with sound waves, CDs are recorded in binary digits as microscopic pits covered by a clear, protective plastic layer. Instead of a needle vibrating in a groove, a laser shines onto the pits, and the reflections are decoded. Audio CDs, as well as all variations of the CD (CD-ROM, CD-R, etc.) use a spiral recording track like a phonograph record, but start at the center, not the edge.
Better Dynamic Range
Digital sound is cleaner than phonograph records because the numbers are turned into sound electronically. There are no needle pops and clicks and no tape hiss if the original recording was digital. In addition, the CD can handle a wider range of volume. A soft whisper can be interrupted by a loud cannon blast. If a phonograph record were recorded with that much "dynamic range," the needle would literally jump out of the groove.
Too Harsh for Critical Ears?
Pops and clicks aside, from the onset of audio CDs, many critics claimed digital sound was harsh and not as musical as the vinyl platter. DVD-Audio and SACD, two advanced digital formats with superior sound quality, came out in 1999, but neither has become very popular (see DVD-Audio and SACD).
In the meantime, turntables and vinyl records are still being manufactured in small quantities, and this legacy industry is expected to persist for a while. See turntable, laser turntable and USB turntable.
(2) (Compact Disc) An optical digital audio disc that contains up to 74 minutes of hi-fi stereo sound. Introduced in the U.S. in 1983, the disc is a plastic platter (120mm/4.75" diameter) recorded on one side, with individual tracks playable in any sequence. Its storage capacity is from 650MB to 700MB. Other forms of CDs, such as CD-ROM, CD-I and Video CD, all stem from the original Compact Disc-Digital Audio (CD-DA) format. CDs can be played in CD, CD-ROM, CD-R, CD-RW and most DVD drives. For more on how CDs are made, see CD-ROM.
Sound is converted into digital code by sampling the sound waves 44,056 times per second and converting each sample into a 16-bit number. It requires approximately 1.5 million bits of storage for each second of stereo sound. The audio tracks are recorded as microscopic pits in a groove that starts at the center of the disc and spirals outward to the edge.
A Note on Terminology
In the early 1990s when CD-ROMs first became popular, "CD" meant music, and "CD-ROM" meant data. Today, "CD" refers to both audio CDs and data CD-ROMs, which also include CD-R and CD-RW media. See CD-ROM.
The Books
Documentation for various CD formats are found in books commonly known by the color of their covers.
Red Book - CD-DA (Audio) Yellow Book - CD-ROM (Data) Orange Book - CD-R, CD-RW, Photo CD (Recordable) White Book - VCD (Video) Blue Book - CD Extra (Audio and data) Green Book - CD-I (Interactive)
What Happened to the Phonograph?
The audio CD was introduced in the U.S. in 1983, and within five years, CDs and CD players exceeded the sales of LPs and turntables.
Carved Sound
Unlike phonograph records, in which the platter is literally carved with sound waves, CDs are recorded in binary digits as microscopic pits covered by a clear, protective plastic layer. Instead of a needle vibrating in a groove, a laser shines onto the pits, and the reflections are decoded. Audio CDs, as well as all variations of the CD (CD-ROM, CD-R, etc.) use a spiral recording track like a phonograph record, but start at the center, not the edge.
Better Dynamic Range
Digital sound is cleaner than phonograph records because the numbers are turned into sound electronically. There are no needle pops and clicks and no tape hiss if the original recording was digital. In addition, the CD can handle a wider range of volume. A soft whisper can be interrupted by a loud cannon blast. If a phonograph record were recorded with that much "dynamic range," the needle would literally jump out of the groove.
Too Harsh for Critical Ears?
Pops and clicks aside, from the onset of audio CDs, many critics claimed digital sound was harsh and not as musical as the vinyl platter. DVD-Audio and SACD, two advanced digital formats with superior sound quality, came out in 1999, but neither has become very popular (see DVD-Audio and SACD).
In the meantime, turntables and vinyl records are still being manufactured in small quantities, and this legacy industry is expected to persist for a while. See turntable, laser turntable and USB turntable.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- CD Duplicate Master 1.0.0.1018 (Windows)
- CD Duplicate Master, a powerful CD duplicate utility, is designed to fit for CD duplicate fan's need. It can enables you to extract digital audio tracks from an audio CD into sound files on your hard disk; burn audio CD, data CD to blank CD disc, and data files to...
- Software downloads 2009-11-06
- Xilisoft Audio Maker 3.0.49.1030 (Windows)
- Xilisoft Audio Maker includes the functions of Audio Converter, CD Ripper, and CD Burner - a multifunctional audio tool. Functions include: as an Audio Converter, it can convert between all popular audio formats, such as MP3, M4A, WAV, WMA, OGG, AAC, AC3, and convert video files to your favorite audio...
- Software downloads 2009-11-06
- Spesoft Audio Converter 2.10 (Windows)
- Spesoft Free Audio Converter is fast, stable, easy yet powerful software that allows you to convert between a large collection of audio file formats. You can convert from MP1, MP2, MP3, OGG, WMA, M4A/MP4/AAC/ALAC, FLAC, WAV, APE, WAVPACK, MUSEPACK, AIF/AIFF, MIDI/RMI, MO3/IT/XM/S3M,/MTM/MOD/UMX, AC3, ADX, OPTIMFROG, SPEEX, TTA, CDA/Audio CD and...
- Software downloads 2009-11-06
- DJ ToneXpress The Ringtone Creator 4.6.4 (Windows)
- Use DJ ToneXpress now iPhone compatible to make unlimited customizable ringtones from your PC music collection, CDs & YouTube videos, and also make unlimited wallpapers, compress full tracks (from PC, CD or YouTube) to play on your cell phone, customize for free the tones on your PC (Yahoo IM, Skype,...
- Software downloads 2009-11-06
- ThumbNailer 10.0.0.6 (Windows)
- Smaller Animals ThumbNailer is a Windows utility that allows you to create thumbnail images and image galleries. You can use it to convert one graphics format to another, change image color depth, resize images, and make HTML thumbnail galleries for the Web or CD.
- Software downloads 2009-11-06
- Phantom CD 1.5.2.2087 (Windows)
- Phantom CD is a virtual CD/DVD emulator. Mount your CD/DVD image files as virtual CD/DVD disc with Phantom CD. Use disc images for your CD and DVD backup. Replace your physical discs to avoid wear and tear on your optical drive, and to avoid disc problems resulted from heat, scratch,...
- Software downloads 2009-11-05
- Digital Music Record Convert Burn Station 7.4.6.41 (Windows)
- Digital Music Record Convert Burn Station is a multi-functional audio recorder, audio converter, music CD ripper and audio CD burning software. With it, you can record, convert, rip, and burn music CD easily, fast, with excellent quality. Five applications are provided: Audio Recorder, Audio Converter, Audio CD Burner, Audio MP3...
- Software downloads 2009-11-05
- GoldWave 5.55 (Windows)
- GoldWave is a professional digital audio editor. Use it to play, edit, mix, and analyze audio, or apply special effects, such as fade, equalizer, echo, reverse, time warp, noise reduction, silence reduction, pop/click filter, voice over, etc. Record new files from cassettes, albums, radio, or microphone and restore and enhance...
- Software downloads 2009-11-05
- AoA Audio Extractor Platinum 2.2.5 (Windows)
- AoA Audio Extractor Platinum - Audio Extractor, Audio Converter, Sound Recording, Voice Changer, Karaoke Recording, all in one. Audio Extractor: extract audio tracks from AVI, MPEG, MPG, FLV Flash Video, Youtube, DAT, WMV, MOV, MP4, 3GP video files and save them as MP3, WAV, iPhone Ringtone, WMA and AC3 formats....
- Software downloads 2009-11-05
- Windows Security Officer 7.5.5.44 (Windows)
- Windows Security Officer is an autonomous provider of log-on and resource restriction security application integrated with, yet independent of, the Windows operating system. It has the capability of providing extremely strong, secure control of who can access a personal computer resources, and exactly what they can do and when they...
- Software downloads 2009-11-05
- Printfolio 1.6.1 (Mac)
- Printfolio is a suite of 5 BeLight Software programs (Business Card Composer, Labels & Addresses, Swift Publisher, Disc Cover and Image Tricks Pro), plus bonus app Art Text works in plugin mode. The suite will assist in creating various printing projects: business cards, CD/DVD art, flyers, brochures, newsletters, catalogs, envelopes,...
- Software downloads 2009-11-05
- Pure Vinyl 3.0PR2b (Mac)
- A suite of audio applications designed specifically for the high quality digital transcription and playback of vinyl LP records. Pure Vinyl is intended for professional or technically-oriented audio enthusiasts, who own high-end equipment, and who want to create, edit and play back the highest possible quality vinyl...
- Software downloads 2009-11-05
- FotoMix 5.2 (Windows)
- FotoMix is a versatile program that allows you to mix and manipulate different backgrounds and foregrounds, to create a wide variety of images. You can use it to: Design eye-catching photo collages, desktop wallpapers, CD and DVD covers, and miscellaneous Web graphics. Add or remove your loved and not so...
- Software downloads 2009-11-05
- Snow Player 1.03 (Windows)
- Snow Player is a tiny, fast, stable, reliable, and completely freeware mediaplayer. Works under all Windows versions. It plays all common well-known audio, video and image formats, internet radio streams (mp3, ogg, wma/asx) playback, built-in scripting interpreter giving to you complete control under player, built-in audio grabber allows you to...
- Software downloads 2009-11-04
- ISO Burner 7.82 (Windows)
- ISO Burner is an easy-to-use ISO Burner to burn MP3, data, ISO, audios, videos, and images to high-quality CDs or DVDs. You can create and burn ISO image file. It can support Long File Name File System, It can supports CD-R, CD-RW, DVD-R, DVD-RW, DVD-RAM, DVD+R, DVD+RW, and DVD+R DL....
- Software downloads 2009-11-04
- Digital Music Record Edit Burn Studio 7.5.0.14 (Windows)
- Not only can you use Digital Music Record Edit Burn Studio to grab music from a CD, but also record audios, in virtually any format. Stop there, and burn your improved, converted audio files to disc. Or use the advanced audio editor to create your own music and songs that...
- Software downloads 2009-11-04
- Wondershare QuizCreator 3.0.0.35 (Windows)
- Wondershare QuizCreator is a robust quiz maker designed for corporate training and online education to create interactive Flash-based quizzes, online surveys and web assessments. This quiz maker software is one of the easiest yet most effective ways to access knowledge and get valuable opinions. Create a Flash Quiz within Minutes...
- Software downloads 2009-11-04
- Setup Factory 8.2 (Windows)
- Setup Factory 8 is the result of over a decade of experience in creating software installation tools. Unlike other installer builders that require week-long training courses in order to get up to speed, Setup Factory was designed to be fast and easy to use. By pairing a visual layout of...
- Software downloads 2009-11-04
- A4Desk Flash Music Player 2.22 (Windows)
- Create an interactive Flash music player to play MP3 music on your Web site. Easy selection of different player skins. No Flash knowledge, coding, or design skill is required. Can publish as an online MP3 jukebox, CD-ROM presentation, or as a standalone application.
- Software downloads 2009-11-04
- IGOR Pro 6.12 (Mac)
- IGOR Pro is an interactive environment for experimentation with scientific and engineering data and for the production of publication-quality graphs and page layouts. IGOR Pro produces publication-quality graphics: IGOR prints at the full resolution of the printer and exports high-resolution graphics formats such as Encapulated PostScript EPS. IGOR Pro can...
- Software downloads 2009-11-04
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
Meet Doc
-
-
Here to help you with your Document Management Needs
- Check out Doc’s Blog on ZDNet
- Help your company, help the earth I want to share with you the Environmental Defense Fund Paper Calculator, which allows you to gauge your organization's environmental impact.
- Which is Greener: Paper or Digital? The Answer May Surprise You Anything we can do to reduce paper consumption is good. But what about the impact of digital waste?
-
Produced by
ZDNet and -
