(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) 1981-2008 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- Palm Treo Pro (unlocked)
- Photo gallery:Palm Treo ProWhile not the best-kept secret in the technology world, with leaked photos and videos all over the Net, we were still amped over Palm's official unveiling of the Palm Treo Pro. And why wouldn't we be? The smartphone looked pretty sharp, both inside and out. However, now...
- Product reviews 2008-08-27
- Can you trust kids with a Kindle?
- Can you trust kids with a Kindle?Can you trust kids with a Kindle?I agree with you for the most part. An electronic book or ereader would be good for looking up information to reference. The drawback I see is the price tag of the kindle, and if someone...
- Discussion threads 2008-08-27
- Microsoft to target Windows XP Pro users with Genuine 'nagware' notifications
- Microsoft to target Windows XP Pro users with Genuine 'nagware' notificationsI don't know what difference it will makePeople who love Windows will still love Windows. People who hate Windows will still hate Windows. People who pirate Windows will still pirate Windows.RE: Microsoft to target Windows XP Pro users with Genuine...
- Discussion threads 2008-08-26
- IDF and the new Mac notebooks
- IDF and the new Mac notebooksI hope the optical drive rumor isn't true...I hope the optical drive rumor isn't true, I want mine integrated.RE: IDF and the new Mac notebooksHmm...Virtually every PC maker has a quad core laptop.Virtually every PC maker has ram support of at least 8GB in their...
- Discussion threads 2008-08-25
- Google and Sirius XM: Build my "Dream" Handheld
- The current rumor-mongering seems to indicate that HTC's "Dream" will soon be making landfall in the US. Based on the initially leaked specs of this device, it still sounds like it doesn't do what I really would want it to do in order to replace by Blackberry 8820. ...
- Blog posts 2008-08-24
- Maxtor Central Axis NAS server
- The Maxtor Central Axis carries a list price of $320, but can be found for as little as $270--a good deal for a network storage device with 1TB of storage. We liked the Central Axis' compact design, fast performance, and that its over-the-Internet access service was easy to set...
- Product reviews 2008-08-22
- M-Audio Studiophile AV20
- We recently auditioned the M-Audio's Studiophile AV 40 stereo speakers, and found a lot to like. Those big, beefy monitors were great for audio from a PC or any other stereo audio source. However, with 4-inch woofers and speakers weighing 14 pounds each, the AV 40s required a design and...
- Product reviews 2008-08-22
- Belkin GoStudio
- If you're a musician, amateur podcaster, or college student looking for a way to capture CD-quality recordings on your iPod, the Belkin GoStudio is an all-purpose solution with some impressive bells and whistles. The GoStudio is not without its flaws, but at $120 you're likely to take its shortcomings with...
- Product reviews 2008-08-22
- Weekend Gadget Guidance: Get MS Office Ultimate for $59.95
- Weekend Gadget Guidance: Get MS Office Ultimate for $59.95No thanksI wouldn't take a free copy of Office...not with that godawful ribbon bar. You know you've screwed up the user interface of a product when a predominant question on websites seems to be "How do I print?". If you...
- Discussion threads 2008-08-22
- TunePat M4P Converter (exe)
- TunePat M4P Converter is an audio and music conversion software which can convert any iTunes M4P files, AAC to plain audio MP3, WAV, WMA files ready for use on any computers or mobile music devices such as iPod, iPhone, PSP, Zune, cell phone, MP3 player and car MP3 CD players.This...
- Software downloads 2008-08-22
- Tune4Mac M4P Converter (txt)
- Tune4Mac M4P Converter for Mac is a iTunes M4P to MP3 music converting tool for Mac OS X. This M4P to MP3 Converter converts unprotected music and purchased iTunes music M4P, M4B, M4A files to plain MP3 with a Virtual CD-RW drive ready for use on any computers or mobile...
- Software downloads 2008-08-22
- Suit over baby vid with Prince song goes forward
- Suit over baby vid with Prince song goes forwardA waste of her time and money.Is this video so important to her that she can't just repost it every time it gets taken down but has to have it up there forever?She's wasting her time and money, and the court's time...
- Discussion threads 2008-08-21
- iTunes Unlimited: music subscription rumor returns
- iTunes Unlimited: music subscription rumor returnsI just don't understandwhy Apple doesn't offer a subscription service. They already have the DRM and authentication services in place. It would cost them very little.But I guess this is Apple. They tell you how you will use their products that you...
- Discussion threads 2008-08-21
- AudioVideoSoft RapidRip (exe)
- RapidRip offers powerful CD ripping and conversion among nearly all audio formats (CD, MP3, WAV, WMA, OGG, AAC, AC3, AIFF, AU, VOX, ADPCM, A-LAW, u-LAW, FLAC, ALAC, M4A, MP4, or WavPack) with ease. Full FreeDB support, configurable CDDB auto-save filenames (using album, artist, title, and/or track) and path creation from...
- Software downloads 2008-08-21
- IncrediFlash Website Template (exe)
- Build a Flash website from selection of professionally designed template without the need to use Adobe Flash. Not everyone is a professional Web developer who are able to use a complicated software such as Adobe Flash to customize their templates. IncrediFlash Website Template Editor is designed with ease of use...
- Software downloads 2008-08-21
- Microsoft, Novell bolster Linux partnership
- Microsoft, Novell bolster Linux partnershipWhy would you want your competition...selling your product and why would you want to sell your competitions product? I would like to believe this is being done for the good of the customer.I'm trying to think of any other industry where this kind of relationship...
- Discussion threads 2008-08-20
- Phantom Drive Starter (exe)
- Phantom Drive installs a virtual recorder in your system that can record all types of virtual CD, DVD, and HD media. Create virtual CDs, DVDs, HD DVDs, and Blu-ray discs from any application that provides a recording command, whether or not you have an optical recorder in the system. You...
- Software downloads 2008-08-20
- MixVibes Producer (zip)
- MixVibes Producer is based on the DVS technology Digital Vinyl Software. It allows you to spin your digital media files (mp3, wave, aiff, ogg vorbis, wma, Audio CDs) from your PC with CD or vinyl decks. All you need is a PC and an audio interface (USB, FireWire, PCI compatible)....
- Software downloads 2008-08-19
- My bad day with Windows Server 2003
- My bad day with Windows Server 2003I'm intrigued...Not by Win2k3 server, but your mention of Ikea furniture. What's that for? Computer desks, lab desks, general tables? My mind is boggling as to what school would let you use that, and what it's being used for!Partition MagicI've had some nasty experiences...
- Discussion threads 2008-08-18
- DEFCON 16: List of tools and stuff released
- Guest editorial by Rob Fuller DEFCON, the 9000+ attendee hacker conference in Vegas has become a sort of hydra conference. It has become more like a global fair than what most people think of conferences; even the badge is highly...
- Blog posts 2008-08-18
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Which solar technology will survive?
-
At the Cleantech Forum in San Francisco, Todd Glass of Heller Ehrman moderates a discussion, among tech execs, on the various solar technologies making a difference in the green movement.
- Watch the video >>
- Access the latest Intel and industry best practices
-
Designed specifically to address the concerns of senior IT managers at organizations with more than 100 employees, the Intel Premier IT Professional Program provides best practices via local and e-Seminars and a members-only Web site.
- View the Intel Premier IT Professional web-site tour >>
-
-
Tasty Baking’s new LEED factory
0:57
Tasty Baking CIO: Brendan O’Malley
-
Balancing act: innovation vs. reliability
1:28
Facebook VP of technical operations: Jonathan Heiliger
-
Securing data at E-Loan
1:47
E-Loan CIO: Jay Shah
-
When crops are scarce
1:47
Del Monte Foods CIO: Marc Brown
- View all CIO Vision Series Videos »
