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What is MP3?
MP3 Conversion
Extracting from an Audio
CD
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Encoding to MP3
It is illegal to encode MP3 files for
trade or sale unless you have the
expressed and explicit permission
of the copyright holder(s).
MP3 is an acronym for Moving Picture Experts Group (MPEG) Layer 3, a type of audio data compression
that can reduce digital sound files by a 12:1 ratio with virtually no loss in quality. It is an efficient way to
store high-quality music or other audio content on your computer. MP3 files can be 1/4 to 1/20 the size
of a commercial CD audio file—yet retain a high sound quality. MP3 files usually have the extension
.MP3, and can be downloaded from the Internet, or can be legally made for personal use from the Audio
CDs that you purchased.
Audio CD extraction is the first phase in the MP3 conversion process. It is the reading of data off an Audio
CD and storing it temporarily on your hard drive.
You need an application that can direct the CD-ROM drive to extract this audio data. This program is
known as a ripper. It reads the data off the Audio CD and in some cases stores it in a file.
The duration of the Audio CD extraction phase depends on many factors. The speed of a CD-ROM drive
is one of the most important elements in overall extraction speed. The speed ratings commonly seen on
CD-ROM drives—such as 8X, 24X, etc.—refers to the speed at which it can read data CDs or CD-ROMs.
Your particular drive may be fast for data, but slow for audio.
Other factors are defects or scratches on an Audio CD. When playing the Audio CD in a CD-ROM drive,
the data lost due to error is negligible. But when data is read incorrectly and put through the MP3 encoding
phase, the distortion is highly noticeable. To avoid this distortion, the Audio CD extraction software may
read the data two or three times to make sure it was read correctly. This error-checking feature is an option
in most Audio CD data extraction software. Be sure error-checking is enabled in your Audio CD
extraction software.
The data extracted from an Audio CD are one of the many types of data an MP3 encoder may process.
Encoders typically expect data to be in .WAV format. They read .WAV data and output MP3 data. These
data are put into an MP3 file.
MP3 encoding is the compressing of data by transforming it into the frequency domain. MP3 encoding/
compression is quality lossy compression and the amount of loss (of quality) is dependent upon the
sampling rate of the output and the bitrate of the output. The higher the sampling and bitrates used, the
better the quality of the sound.
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