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INTRODUCING ABOUT DISC
Teacher:
Nguyen Minh Phuong.
Group 4:
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Truong Truong Vi Lam
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Ta Thanh Chung
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Tran Van Tu
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Vu Van Tai
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Vu Thanh Nam
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Le Duyen Tinh
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
Definition
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History
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Structure
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Funtion
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Kind
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COMPACT DISC
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DEFINITION
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The compact disc was the first digital medium designed for the consumer market and has become the
most popular medium for commercial releases
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A Compact Disc (CD) is an optical disc used to store digital data, originally developed for storing digital

audio.
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The CD remains the standard physical medium for commercial audio recordings.
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It is a small, portable, round medium made of molded polymer (close in size to the floppy disk) for
electronically recording, storing
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HISTORY
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The compact disc, now commonplace in stereos and computers, was invented in the late 1960s by
James T. Russell.
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Starting in the mid 1980's, compact discs (CD) began to take over both the audio and computer
program market.Originally designed and developed by both Sony and Phillips
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HISTORY
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In 1982: Manufacturing of CDs began on a large scale in factorys.
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In 1984 both companies extended the technology so it can be used to store and retrieve data an so the
CD-ROM was born. Since then, the compact disc has change significantly the way we listen music
and store data.
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In 1990 again Philips and Sony expand the technology and created the Recordable compact disc (CD-
R). Up to then, the CDs were manufactured by industrial stamping with a master made from the
original.
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HISTORY
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Nowaday, CD is very popular in our life. And I think it’ll continually develop in future.
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STRUCTURE
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Physical CD is like a thick plastic material made of approximately 0.25 inches (1.2 mm) with a layer of
transparent polycarbonate.
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CD is a single track (Track) spiral to store data, this track spiral direction round the disc continuously
from the outside.
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In fact, the spiral track starts in the middle, which means that CD may be smaller than 4.8 inches in
size. So there are some types of plastic cards such as Business Card can be read by CD Player. A CD
Business Card is about 2 MB non-spiral groove.
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STRUCTURE
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On the CD, the track size is very small width of about 0.5 micron and the grooves
are separated by an approximately 1.6 micron.
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With such dimensions, but if the total length of the spiral track on a CD would be a
staggering figure of about 5 km.
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Data structure
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The smallest entity in a CD is called a frame, which consists of 33 bytes and contains six complete 16-bit
stereo samples (two bytes × two channels × six samples = 24 bytes). The other nine bytes consist of eight
CIRC error-correction bytes and one subcode byte, used for control and display.
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Each byte is translated into a 14-bit word using eight-to-fourteen modulation, which alternates with three-bit
merging words. In total there are 33 × (14 + 3) = 561 bits. A 27-bit unique synchronization word is added, so

that the number of bits in a frame totals 588 (which are decoded to only 192 bits music).
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Data structure
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These 588-bit frames are in turn grouped into sectors. Each sector contains 98 frames, totaling 98 × 24 = 2352
bytes of music. The CD is played at a speed of 75 sectors per second, which results in 176,400 bytes per
second. Divided by two channels and two bytes per sample, this results in a sample rate of 44,100 samples per
second.
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Data structure
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For CD-ROM data discs, the physical frame and sector sizes are the same. Since error concealment cannot be
applied to non-audio data in case the CIRC error correction fails to recover the user data, a third layer of error
correction is defined, reducing the payload to 2048 bytes per sector for the Mode-1 CD-ROM format. To
increase the data-rate for Video CD, Mode-2 CD-ROM, the third layer has been omitted, increasing the
payload to 2336 user-available bytes per sector, only 16 bytes (for synchronization and header data) less than
available in Red-Book audio.
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Data structure
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"Frame"
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For the Red Book stereo audio CD, the time format is commonly measured in minutes, seconds and
frames (mm:ss:ff), where one frame corresponds to one sector, or 1/75th of a second of stereo sound. In
this context, the term frame is erroneously applied in editing applications and does not denote the
physical frame described above. In editing and extracting, the frame is the smallest addressable time
interval for an audio CD, meaning that track start and end positions can only be defined in 1/75 second
steps.
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Data structure

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Logical structure
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The largest entity on a CD is called a track. A CD can contain up to 99 tracks (including a data track for mixed mode discs).
Each track can in turn have up to 100 indexes, though players which handle this feature are rarely found outside of pro audio,
particularly radio broadcasting. The vast majority of songs are recorded under index 1, with the pre-gap being index 0.
Sometimes hidden tracks are placed at the end of the last track of the disc, often using index 2 or 3.
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This is also the case with some discs offering "101 sound effects", with 100 and 101 being indexed as two and three on track
99. The index, if used, is occasionally put on the track listing as a decimal part of the track number, such as 99.2 or 99.3. (
Information Society's Hack was one of very few CD releases to do this, following a release with an equally obscure CD+G
feature.) The track and index structure of the CD carried forward to the DVD as title and chapter, respectively.
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FUNTIONS
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More than 200 billion CDs have been sold worldwide since then and it remains the dominant format
despite the growth in digital downloads.
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CDs and DVDs are everywhere these days. Whether they are used to hold music, data or computer
software, they have become the standard medium for distributing large quantities of information in a
reliable package. Compact discs are so easy and cheap to produce that America Online sends out
millions of them every year to entice new users. And if you have a computer and CD-R drive, you can
create your own CDs, including any information you want.
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In this article, we will look at how CDs and CD drives work. We will also look at the different forms
CDs take, as well as what the future holds for this technology.
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FUNCTIONS
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A compact disc (CD) is a small, portable, round medium made of molded polymer (close in size to the floppy disk) for

electronically recording, storing, and playing back audio, video, text, and other information in digital form. Tape
cartridges and CDs generally replaced the phonograph record for playing back music. At home, CDs have tended to
replace the tape cartridge although the latter is still widely used in cars and portable playback devices.
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Initially, CDs were read-only, but newer technology allows users to record as well. CDs will probably continue to be
popular for music recording and playback. A newer technology, the digital versatile disc (DVD), stores much more in
the same space and is used for playing back movies.
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FUNCTION
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CD is so common today.
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They are used to burn music, data or computer programs.
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It became a standard tool to store information in large quantities, cheap reliable and
easier to manufacture.
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Only with a personal computer and a CD-R drive, users can create their own CDs
with any information they want. A CD can store up to 74 minutes of music
equivalent to the amount of digital data is 783 MB.
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KIND
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We have some kinds of CD which we want to introduce with you. Those’re not all, but we hope we’ll give
you some useful informations about CD.
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Now, let’s discover! We have some kinds of CD :
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CD text
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CD Graphics
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CD Rom
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Video CD
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Photo CD
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CD R
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CD WR
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CD-i, Enhanced CD…and else…
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CD text
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Compact Disc that allows for the storage of information like song name, artist,
album name as text along with the standard audio data on the CD.
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CD Graphics
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These contain additional graphics data on the CD. They run normally on a normal
CD player, but can output graphics data when played on a CD+G player.
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CD ROM
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Now which phase is ROM acronymed of ?
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ROM is acronymed of Read Only Memory.
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So, CD ROM storage datas which can only be read.
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Example: GHOST CD, Sortware CD…
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Video CD and Photo CD
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Video CD - Video CDs or VCDs are CDs with video data.
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Photo CD - it was designed by Kodak for storing photos digitally in a Compact Disc. They were
able to store more than 100 images when first launched.
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CD R and CD RW
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CD R (Compact Disc - ReadOnly) –audio and storage
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CD RW (Compact Disc - Rewritable)- these are CDs on which data can be written, erased and re-
written more than once.
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A CD PLAYER
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A Compact Disc player (often written as compact disc player), or CD player, is an
electronic device that plays audio Compact Discs. CD players are often a part of home
stereo systems, car audio systems, and personal computers. They are also
manufactured as portable devices. Modern units can support other formats in addition
to CDs, such as DVDs, CD-ROMs with audio files and video CDs. DJs often use players
with an adjustable playback speed to alter the pitch of the music programme. CD
playback functionality is also available on CD-ROM/DVD-ROM drive equipped computers
as well as on DVD players and CD-ROM/DVD-ROM based game consoles.
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Read a CD by CD player

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The compact disc, although appearing to be stationary in the tutorial, should actually be envisioned
as rotating at high speed. A beam is emitted by the laser and directed onto a single track on the disc
by the prism/beamsplitter. As the disc rotates, the beam encounters a series of pits and landings that
determine whether the beam is reflected back into the detector (from a landing) or scattered (a pit).
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Read a CD by CD player
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Light from the laser beam must penetrate a thin protective layer of plastic (not illustrated) on the
disc before striking the reflective coating that contains pits and landings.
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As the disc rotates, light reflected from landings on the disk strikes the photo sensor producing a
series of electrical pulses that are coordinated with a timing circuit to generate a stream of 1s and 0s
that produce the binary code of information on the disc.
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At the bottom of the tutorial, a simulated bit reader continuously streams the binary code as it is
retrieved from the disc.