Báo cáo tiếng anh chuyên ngành CNTT: Compact Disc

* DEFINITION*The compact disc was the first digital medium designed for the consumer market and has become the most popular medium for commercial releases *A Compact Disc CD is an optica

* DEFINITION

*The compact disc was the first digital medium designed for the consumer market and has become the most popular medium for commercial releases

*A Compact Disc (CD) is an optical disc used to store digital data, originally developed for storing digital audio

* The CD remains the standard physical medium for commercial audio recordings

*It is a small, portable, round medium made of molded

polymer (close in size to the floppy disk) for electronically recording, storing

* HISTORY

* The compact disc, now commonplace in stereos and

computers, was invented in the late 1960s by James T Russell

* 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

* HISTORY

*In 1982: Manufacturing of CDs began on a large scale in factorys

*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

*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

* HISTORY

*Nowaday, CD is very popular in our life And I think it’ll continually develop in future

* STRUCTURE

*Physical CD is like a thick plastic material made of

approximately 0.25 inches (1.2 mm) with a layer of

non-spiral groove

* Data structure

*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

*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)

* Data structure

*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

* Data structure

*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

* Data structure

*"Frame"

*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

* Data structure

*Logical structure

*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

*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.

* FUNTIONS

*More than 200 billion CDs have been sold worldwide since then and it remains the dominant format despite the growth in digital downloads.

*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.

*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.

* FUNCTIONS

*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.

*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.

* 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.

* KIND

*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.

*Now, let’s discover! We have some kinds of CD :

* CD text

* 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.

* CD Graphics

* 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.

* CD ROM

*Now which phase is ROM acronymed of ?

*ROM is acronymed of Read Only Memory.

*So, CD ROM storage datas which can only be read.

*Example: GHOST CD, Sortware CD…

* Video CD and Photo CD

*Video CD - Video CDs or VCDs are CDs with video

* CD R and CD RW

*CD R (Compact Disc - ReadOnly) –audio and storage

*CD RW (Compact Disc - Rewritable)- these are CDs on which data can be written, erased and re-written more than once

* A CD PLAYER

*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 ROM based game consoles

CD-ROM/DVD-* Read a CD by CD player

*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)

* Read a CD by CD player

*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

*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

*At the bottom of the tutorial, a simulated bit reader

continuously streams the binary code as it is retrieved from the disc

* The technology used on the current disc

* AFFM TECHNOLOGY

*This technology is changing the air flow to reduce drive noise Noise and vibration are two major causes of

headaches when users use a high speed drive

*AFFM is designed to change the uneven airflow inside the drive to help distribute pressure evenly to bring the process of peaceful and stable

* Flextra Link TM

TECHNOLOGY

*The phenomenon of "failed" disk error is usually caused

by running buffer in the conventional optical disk, which appears when the system can not guarantee a steady

stream transmitted to the burner, creating the "point

blank" on the disk

*FlextraLink against the above phenomenon in the

process of writing data by marking stops while recording and continue recording at the same point when

information flow begins again

* Flextra Speed TM

TECHNOLOGY

*FlextraSpeed continuously monitors the recording

process and choose the burning speed to ensure optimum processing burner for best quality As a result, the

accuracy and reliability are enhanced when reading / writing / recording on a large variety of disk formats that have been certified The process operates with optimum speed also effective in reducing noise, prolongs motor life and saves CPU resources

* AVRS TECHNOLOGY

*Automatically shake Reduction technology AVRS is

designed to minimize the vibration caused by the spindle motor and resonance between components as well as

between the drive and PC case

*AVRS is designed to reduce vibration and noise caused

by the imbalance of rotating mechanical process

professional label.

* QUIE TRACK

TECHNOLOGY

*QuieTrack innovative technology was developed to

reduce noise emanating from the drive that everyone can recognize it while improving stability

* ULTRA DMA2

TECHNOLOGY

*A technology offers the ability to access data with

extreme speed 33.3Mb / s It combines with WriteMaster technology to create the perfect duo to support the disc

* I.B.S TECHNOLOGY

*As technology retains priority for disk buffers when you are recording, which minimizes the possibility of "failed" disk interrupted by the level of the program due to an

accounting program while recording another

* I-BURN TECHNOLOGY

*This is new technology - the perfect solution is used to help the selection of flexible recording speed from the first recording to create the qualifiable and durable discs

* VRS & Ultra Design

TECHNOLOGY

*It’s perfectly designed to help the reading and writing datas becomes slicker and suits every working

environment

* I-SPEED TECHNOLOGY

*I-Speed assists you better in reading the CD which has the vary recording speeds due to ability to adjust the reading speed

* GAME…

* GAME…

*I have 5 words And they are the implications for our keyword

in this game And your task is to find the five words through

my questions Each word which you answer correctly, you will receive a letter for keyword You can choose any question you want If you guess my keyword, you will receive a special gift

in this game.

*Are you ready?

* GAME…

E

R A M E