What is the new technology of CD

compact disc

Without noise and searching

The CD is also a disc, but it works fundamentally different from a vinyl record. It is actually not a sound, but a data carrier, as the music is stored on it in the form of digital data. The music industry needs to convert the music into digital information before putting it on a CD.

The great advantage of CD technology is that a laser beam in the CD player scans the disc without contact. The surface of a CD is therefore not scratched or worn away by a needle, as is the case with a turntable. The noise caused by dust on the needle when playing records is also a thing of the past.

In contrast to the record, the CD is only recorded on one side. This eliminates the need to turn around after half the game time. The digital technology also allows direct access to every piece of music without delay.

How does a CD work?

And this is how it is done: As with all modern sound recording processes, a microphone converts sound into electrical current. The electrical signals are then converted into a digital, binary number code and stored.

This process is called pulse code modulation (PCM) and converts the continuous analog signals into subdivided digital signals. The binary code practically translates the sound information into a computer-readable form.

The binary code, like the Morse code (dot and dash), consists of two characters, namely 0 and 1. With a combination of these two characters it is possible to represent any kind of information. If the music is in binary code, it can be transferred to the CD.

A CD has several layers. One of these layers is made of reflective metal, such as aluminum. The data of the binary code are imprinted in this layer with the help of tiny pits and smooth areas in between ("lands"). The resulting pattern on the surface of the CD is called the pit structure.

The laser beam of a CD player scans the CD disk from the inside out. When reading out the pit structure, the laser beam is reflected differently from the depressions and the smooth areas. A light-sensitive photodiode converts these reflections into electrical signals.

An amplification of the signals enables the output via loudspeakers. These transform the signals back into the original sound waves.

The blank: burn it yourself instead of buying it

In 1991 the introduction of the write-once "Compact Disc Recordable" (CD-R), the so-called blank, set off an avalanche. From now on, computer owners could create or burn their own CDs with a CD burner. All you need is music in digital form, i.e. as an audio file.

MP3 is displacing the CD

The situation on the music market has changed again in recent years. External hard drives, music streaming services and cloud storage are increasingly pushing the CD into the background as a storage medium. While around 600 million blanks were sold in Germany in 2005, the figure was 50 million in 2018, i.e. less than a tenth.

Nevertheless, after initial teething problems, the music industry has adapted to the situation of digitally available music. In 2013, according to the Federal Music Industry Association, it was able to record an increase in sales for the first time in 15 years.

In 2017, digital music sales and streaming services now accounted for around 47 percent of sales. Physical sound carriers such as the CD and the LP, which is becoming more popular again, still achieved more than half of sales at around 53 percent.