Specifications

Chapter 2 – Background

2.1 What are MP3s?

MP3 stands for MPEG Audio Layer 3. MPEG is the name of a working group

established under the joint direction of the International Standards

Organisation/International Electrotechnical Commission (ISO/IEC), whose goal is to

create standards for the compression of digital video audio. More precisely, MPEG

defines the syntax of audio and video format needing low data rates, as well as

operations to be undertaken by decoders. [16]

Layer 3 is one of three coding schemes (Layer 1, Layer 2 and Layer 3) for the

compression of audio signals. Layer 3 uses perceptual audio coding and psychoacoustic

compression to remove all superfluous information from the audio signal. It removes

the data from the audio signal which represents the physical sound components the

human ear cannot here. [17]

The result in real terms is Layer 3 shrinks the original sound data from a CD (with a bit

rate of 1411.2 kilobits per one second of stereo music) by a factor of 12 (down to 112-

128kbps) without sacrificing sound quality. [17] Bit rate denotes the average number of

bits that one second of audio data will consume.

With this reduction of size and the increase in the use of the internet, MP3s have

become very popular. Ideally, they have made it now possible to purchase

downloadable music online and download the music in relatively little time.

Consequently, music stores will eventually become redundant and music groups will

perhaps discard their record producers. At the moment there are very few options for

purchasing music online therefore MP3 distribution has largely been done illegally. Use

of MP3s does not have to be illegal though. If one purchases the music on CD and

decides that using CDs is cumbersome, it is legal to convert the CD into MP3 data for

your own personal use.