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- McAlpine Design Ltd.
(c)
1999-2005
|
What
is MP3 Audio?
MP3
is an abbreviation for "Motion
Pictures Experts Group Layer-3".
It was originally developed for
high quality digital film audio
soundtracks, but was soon
adapted by the market as a
quality method to compress all
types of audio. Today it has
become the most popular standard
of audio compression on the
Internet. In the high quality
compression mode, MP3 compresses PCM audio by 11 times with very
little perceived loss of audio
quality. You can store around 11
hours of music or 160 stereo
audio tracks on a single 650MB
CD-Rom when using the 128Kbps
compression rate. A regular
Audio CD which has
non-compressed Digital PCM
encoding provides 74 Minutes of
audio on the 650MB CD. MP3 is
the ideal format to download
audio from Internet web-sites, a
typical MP3 audio track (at 128Kbps) is
around 4MB (ie 1MB=1minute).
The Apple
ipod
The 60GB MP3 player
can hold 15,000 songs.
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-
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- MP3
PORTABLE PLAYERS
- Many portable pocket
size players MP3 players are
available. The MP3
files are either
downloaded from the
internet and transferred
into the player
memory via the USB bus. Or audio CD's
are ripped on the computer by widely
available software and
converted
in the PC into the MP3
audio format. One of the most popular players in the UK
is the Apple ipod.
-
- The
Apple IPOD
- Various models are avalable in
the IPOD range, shown on the left is the top of the range 60Gb
colour lCD version that costs £299 in the UK. The 20GB version
costs £209 and can hold around 5000 songs.
Compression rates
vs a standard CD:
| Format |
Data
rate |
Sample
frequency |
Data
size/ minute |
Typ.
Four minute |
|
MP3 (x-High) |
192Kbps |
44100HZ |
1.44MB/Min |
5.76MB |
| MP3
(High) |
128Kbps |
44100HZ |
0.96MB/Min |
3.84MB |
| MP3
(Mid) |
64Kbps |
22050HZ |
0.48MB/Min |
1.92MB |
| CD (PCM) |
1413Kbps |
44100HZ |
10.6MB/Min |
42.4MB |
Note: PCM stands for
"Pulse Code
Modulation" which is
uncompressed digital
audio. |
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