CD and its standards

It contains description about CD & its standards

1. & its Standards 1 By Tamanna Sehgal

2. Contents Objective History Introduction Physical Details of CD Working Principle of CD Various Standards of CD Comparison b/w magnetic & optical media Summary FAQs? References 2

3. Objective List the benefits of optical media Explain how data is organized, accessed, and processed. Explain different CD Formats such as CD-DA,CD- R,CD-RW,CD- i etc. Comparison between optical & magnetic media. 3

4. History A CD (Compact Disk) is an optical media storage device, originally developed by Philips and Sony and introduced as  CD-Digital Audio  (CD-DA) in 1980. CD-DA was originally developed to contain only audio information. The Compact Disc Digital Audio Standard, commonly referred to as the Red Book. Extensions to the Red Book standard were developed for storing computer data, compressed audio, video, and graphical information on CD. 4

5. Optical Disks Compact Permanent storage Two common types CD DVD 5

6. Compact Disc Optical format From 650 MB to 1 GB capacity Disks made of reflective material; how each bit reflects light--or doesn't reflect it--determines whether it's a 1 or a 0. Types Read only: CD-ROM Write once: CD-R Rewriteable: CD-RW Picture CDs and Photo CDs 6

7. Physical details of CD The compact disc consist of polycarbonate substrate 120mm in diameter 1.2mm in thickness. The polycarbonate layer contains microscopic pits. Each pit is 100nm in depth & 500nm in width. The space between two pits is called lands. The polycarbonate substrate is covered by reflective aluminium or gold to increase reflectivity. The reflective surface is protected by a layer of lacquer to prevent oxidation. 7

8. CD Layers 8

9. Working Photo cell CD Rotation Digital pulse(O/P) Infrared laser light Laser diode lens prism 9

10. Working Lands reflects the laser beam light. Pits diffuses the light. Lands & pits convey binary values. The reflected light falls on a photo detector. It sense the presence of a land or pit by the intensity of light falling on it. A photocell changes light energy into electrical energy. 10

11. CD Layers 11

12. Reading data 12 1 1 1 1 0 1 0 1 1 1 1

13. Contd ….. A transition from a land to pit or a pit to land is interpreted as a ‘1’ & Absence of a transition is interpreted as a ‘0’. 13

14. Standards and Specifications According to industry legend, at least the original CD specification (the Red Book) was released in a booklet with a red cover. Although each of the specifications have formal titles, they are generally referred to as different colors of books. Colored books are a set of books that outline disc system specification. Specifications are classified by book colors. 14

15. Contd… Book color Description Red Physical properties of compact disc audio Yellow Requirements for using CD technolog y for computer data storage system. Green Specifications of interactive CD technology. Orange Describes recordable CD media. White Describes video standards. 15

16. Various CD Standards CD-DA(Compact Disc-Digital Audio) CD-ROM(Compact Disc-Read Only Memory) CD- i (CD Interactive) CD-ROM/XA(CD ROM Extended Architecture) CD-R(Compact Disc-Recordable) CD-RW(Compact Disc-Rewritable) Video CD 16

17. CD-DA(Compact Disc-Digital Audio) First CD Format which defined the audio CD. It was developed by Philips & Sony in 1980. Audio data is stored on the disc in block which are also some times called sectors. Each block holds 2352 bytes of data. 75 blocks are required for each second of sound. Audio specificaton does not include any copy protection mechanism & the disc can be easily duplicated . 17

18. CD-ROM(Compact Disc-Read Only Memory) Yellow Book is an extension of the Red Book that enables the CD to contain data other than the audio data. Data CD Standard include two modes: CD-ROM, Mode 1 is the standard data storage mode used by almost all standard data CDs (CD-ROMs). 2,352 bytes of data in each block, 2048 are allocated for the data . The remaining 304 bytes are used for added error detection and correction code. 18

19. CD-ROM(Compact Disc-Read Only Memory) CD-ROM, Mode 2 Contain 2336 bytes of user data . It is the same as Mode 1, except that the error detection and code correction bytes are not included. The Mode 2 format offers a flexible method for storing graphics and video. It allows different kinds of data to be mixed together. 19

20. CD- i (CD Interactive) The Green Book is the informal name for Philips and Sony's 1986 specification document for CD-Interactive (CD- i ). In this authors creating disks including text, graphic, audio, video, & computer program & H/W sold to handle all of these & connect to a television screen for output. A CD-I player represent a stand alone system that required no external computer. It plugged directly into a TV & stereo system & came with a remote control that allowed the users to interact with S/W prog sold on discs. 20

21. CD-ROM/XA( Cd ROM Extended Architecture CD-ROM XA was developed jointly by Sony, Philips and Microsoft. CD-ROM XA is a modification of CD-ROM It defines two new types of sectors that enable it to read and display data, graphics, video, and audio at the same time. 21

22. CD-R(Compact Disc-Recordable) Orange Book is the informal name for Philips and Sony's Recordable CD Standard  published in 1990. The Orange Book is divided into three sections: Part I deals with magneto-optical drives(Magneto-Optical (CD-MO) technology that are rated to allow millions of rewrites) ,& Part II deals with the first recordable CD format CD-R (Compact disc - Recordable). Part III, released separately, detailed CD-RW (Compact disc - Rewritable). After the Orange Book, any user with a CD Recorder drive could create their own CDs from their desktop computers. 22

23. CD-RW(Compact Disc-Rewritable) Rewritable CD (CD-RW) was developed by Philips and Sony in 1996, as an extension to the original Orange Book. This addition specifies the use of Phase Change technology. CD-RW makes it possible for the user to write and rewrite the disk. 23

24. Video CD The White Book specification was developed in 1993 by Philips and Sony. To cover the Video CD format. 24

25. Summary Optical media have a number of advantages over magnetic media such as the floppy disk. One optical disc holds about the equivalent of 500 floppies worth of data. Durability is another feature of optical media; they last up to seven times as long as traditional storage media. Also, the life span of optical media is much greater than that of magnetic media. 25

26. FAQs? Q1. What kind of storage media should we use? There are a number of storage media types that you can choose from, including tapes, CDs, DVDs, various mini-drives, or even hard drives. Discuss your storage needs with your Records Management (RM) and Information Technology (IT) staff. Your RM staff can advise you on how to identify and organize your e-records when you transfer them onto physical media, and your IT staff can advise you about technology choices or issues. Q2. What are CDs? Compact Disc-Read Only Memory (CD-ROM), is a type of optical disk capable of storing large amounts of data - up to 1GB (gigabyte) - although the most common size is 650MB (megabytes). A single CD-ROM has the storage capacity of 700 floppy disks with enough memory to store about 300,000 text pages. 26

27. Contd…. Q3.What is the shelf life of unrecorded CD-R/DVD-R discs? It is best to purchase new CDs/DVDs as they are needed. According to the Optical Storage Technology Association (OSTA), the unrecorded shelf life of a CD-R/DVD-R disc is conservatively estimated to be between 5 and 10 years. Q4. How should we handle CDs and DVDs? Handle discs only by the outer edge or the center hole, never by touching the surface. Fingerprints can disrupt the tracking of the laser on the disc. Follow the manufacturer's instructions to remove any dirt, fingerprints, or smudges. Q5. What is the preferred method for labeling CDs/DVDs? CDs and DVDs or their containers are labeled in some form or fashion so that they can be identified and organized according to your inventory. Many vendors sell CD-safe markers. For risk-free labeling of any disc, it is best to mark the clear inner hub or the so-called mirror band of the disc where they contain no data. Do not apply adhesive labels to the CD/DVD because they can damage the disc. 27

28. Contd…. Q6.How do we store the discs to extend their useful life? Discs are best stored upright (like a book) in "jewel" cases that are designed specifically for CDs/DVDs. Ideally, store the cases in plastic or steel containers manufactured specifically for the type of medium in cool, dry storage that is free of large temperature fluctuations. Generally, useful life will be increased by storing discs at a low temperature and low relative humidity, since chemical degradation is reduced in these conditions. Store at 62-70 degrees F. and 35-50% relative humidity. Q7. What is the preferred method for destroying CDs/DVDs?   When temporary records reach the end of their retention period, or if damage occurs to media while in storage, you will want to ensure that the data are irretrievable. Using industrial shredders or disintegrators is the preferred method of destruction. Shredding or disintegrating the media will ensure that no confidential, classified, personally identifiable, or privacy-protected information is left unprotected or available for unauthorized use. Shredders should meet NSA specifications for High Security Disintegrators and Optical Media Destruction Devices . Some agencies have special requirements for media destruction so you should check with your RM and IT departments before recycling or destroying media. A number of commercial vendors provide recycling services for optical media. 28

29. References Principles of Multimedia By Ranjan Parekh http://www.archives.gov/records-mgmt/initiatives/temp-opmedia-faq.html http://whatis.techtarget.com/reference/Fast-Guide-to-CD-DVD http://en.wikipedia.org/wiki/Compact_Disc http://wiki.answers.com/Q/What_is_the_difference_between_a_magnetic_disk_and_an_optical_disk http://www.ehow.com 29

30. THANKS…………. 30