Before
you use mp3, you should fully
understand exactly what it is
MP3 stands for MPEG
Audio Layer-3. In 1987, the Fraunhofer
IIS-A started to work on perceptual audio coding. In a joint
co-operation with the University of Erlangen, the Fraunhofer
IIS-A finally devised a very powerful algorithm that is standardized
as ISO-MPEG Audio Layer-3 (IS 11172-3 and IS 13818-3).
Before encoding to mp3, digital audio signals typically consist
of 16 bit samples recorded at a sampling rate more than twice
the actual audio bandwidth (e.g. 44.1 kHz for Compact Discs).
So you end up with more than 1400 K/bit to represent just one
second of stereo music in CD quality. By using MPEG audio encoding,
you may shrink down the original sound data from a CD by a factor
of 6 (sometimes more) without losing sound quality. Factors
of 10 and even more still maintain a sound quality that is significantly
better than what you get by just reducing the sampling rate
and the resolution of your samples. This is realized by perceptual
coding techniques addressing the perception of sound waves by
the human ear. Basically, this means that mp3 compresses the
audio file by "throwing away" data that your ears
can't hear anyway, and, depending on the bit-rate used, can
maintain the original CD sound quality.
By exploiting stereo
effects and by limiting the audio bandwidth, the encoding schemes
may achieve an acceptable sound quality at even very low bit-rates.
MPEG Layer-3 is the most powerful member of the MPEG audio coding
family. For a given sound quality level, it requires the lowest
bitrate - or for a given bitrate, it achieves the highest sound
quality. In all international listening tests, MPEG Layer-3 has
consistently and impressively proved its superior performance
above all other compression techniques.
The bit-rate you choose for mp3 encoding has been the subject
of much debate and, although you don't have to worry about any
of these technicalities when you buy backing tracks from us (we've
done all the mp3 encoding for you), we do discuss bit-rates in
more depth in our article on MP3
Bit Rates For Backing Tracks.
MP3 audio has many advantages over other music formats and not
just because of it's quality and size. The main advantage to you
as a singer, entertainer or musician is that mp3 is kinder to
your PA system. if you're a singer, you probably use thousands
of pounds or thousands of dollars worth of hi-tech musical equipment
to play you backing tracks and many singers experience speakers
blowing from time to time (which is always costly to repair because
most blown speakers can't be repaired and need to be replaced
with new ones).
One of the main causes of damage to speakers is too many frequencies
above or below the speakers capacity being pumped through it.
This is where mp3 really gains a massive advantage over CD, minidisc
and all other formats. You see, the frequencies that mp3 throws
away (ie the frequencies that your ears can't hear - remember
we discussed this above), are the very frequencies which damage
your speakers! A horn will blow if you try to pump higher frequencies
through it than it can handle. A bass bin will blow if you try
to pump lower frequecncies through it than it can handle.
However, if you have encoded your music to mp3, the ultra high
frequecncies which the human ear cannot hear will have been removed
and, likewise, the lower frequencies which the human ear can't
hear will also have been removed.
This results in cleaner audio and safer frequencies and so helps
protect your PA system.
Written by Kenny Campbell
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(all rights reserved)
This article cannot
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