CD-ROM Digital Audio (CD-DA) introduction

The Compact Disc Digital Audio (CD-DA) is an optical disc normally used to store music. Philips and Sony created Red Book to set the necessary parameters for the CD-DA. This Red Book forma the basics for all the other CD standards.

History of CD-DA

The compact disc was developed 25 years ago and it molded the music landscape over the years. CD-DA is the result of digital revolution, and it was first introduced in 1982 by Philips. This CD-DA project was launched following the failure of video disc technology.

CD-DA is similar to standard WORM format CDs. In 1985, CD-ROM for file sharing and in 1990, CD-Recordable were brought in. The Visitors by Abba and a recording of Herbert Von Karajan was the first CDs pressed. In the year 2000, global sales of compact disc topped at 2.455 billion.

How CD-DA Works

The music signal is described in the form of series of binary notations called bits. These bits are recorded as pits and lands on the discs. Pits and lands symbolize 0’s and 1’s accordingly. From these digital entries, the CD rebuilds the original audio signal.

The measuring of this signal is done bit by bit, and it is known as sampling. 16 bit coding forms digital words, and computers use binary notation to read it. Coded info is read by laser beam and data is sent to decoder to covert in to digital information. DAC converts digital info in to analog audio wave. And finally microprocessor controls volume, tone, etc.

Technical Information

The CD-DA is a thick disc of 1.2mm made from polycarbonate plastic coat with a thin layer of aluminum, and it is protected by layer of lacquer. The CD-DA is available in various sizes, but commonly used one is 120mm in diameter. These discs stores approximately 74 minutes of music.

The right of the CD-DA logo on the disc is owned by Philips, a Dutch electronics company. The format of CD-DA is a 16 bit PCM encoding in two channels at the rate of 44.1 kHz. Without corrupting the content, Reed-Solomon error correction protects the CD-DA when it is scratched.

Copy Protection

The CD-DA specification does not include any copy protection system and the compact discs can be easily duplicated or the content can be removed. In 2002, recording companies attempted to market copy protected CD-DA. Because of this, the music player error correction will allow the music to play, while the CD-ROM of computer fails with errors.

Copy protected compact discs of recording companies that do not correspond to Red Book spec are not allowed to have the Compact Disc Digital Audio logo. It is said that the new model of Philips’ CD recorders will be made to record from protected discs.

Advantages of Using CD-DA

The main advantage of CD-DA is, unlike other techniques, these compact discs reproduce the original music signal exactly without the need for coloration or equalizing. The CD-DA is smaller in size, stores large data, low making cost and physically robust.