MP3's - From Apples To Kegs
By: Paul Sonoda
Unless you have been hiding under a rock, MP3 are the latest craze for music portability. Of course, you will need to know about compatibility with different file formats and players. Or maybe you want to integrate your iPod into your car stereo system. The real question is...are you prepared?
View from the cheap seats:
If you own a computer and you surf the internet, chances are you have heard of MP3. MP3 is audio format made popular in the world of computers and the internet. So what is so appealing about this audio format? The answer is reduced file size. MP3 can compress a standard audio file to a file size less than one tenth of the original size. MP3’s smaller file size makes your music extremely portable. Let’s take a closer look at the process.
back 
topHow MP3s Work:
Originally developed in Germany in 1991 by the Fraunhofer Institute, MP3 (MPEG Audio Layer 3) is an audio compression technology that is part of the MPEG-1 and MPEG-2 specifications. MP3 compresses CD quality sound into significantly smaller file size with near the same music fidelity. To create MP3 you will need a “ripper/encoder” and “decoder”.
A ripper/encoder is a program that converts an existing audio file from a CD or other source into the MP3 format. There are many coders available for a nominal fee on the internet. Not all ripper/encoders are the same. When choosing a ripper/encoder, make sure that it is capable of coding MP3 at different sampling rates. The higher the sampling rate the better the sound quality but the larger the file size. Lower sampling rates will yield smaller file size but reduced sound quality. How MP3 technology makes smaller audio files deserves closer inspection.
Ringside:
To reduce file size, MP3 does not try to maintain the same audio signal after the encoding-decoding process, but uses the trickery of perceptual coding and intuitive coding to create smaller audio file that sounds identical to the human ear. The two coding techniques form an ideal compliment. When there is a complex musical passage, there are many sounds in the recording that are masked (we do not perceive) and perceptual coding techniques use this fact to remove this audio information from the recording. During simpler musical passages (or pure sounds) there are few masking effects but intuitive coding is very effective because this digitizes signal contains many repetitive bytes that can be replaced with shorter codes.
File size is all about “Bitrate”
I started with the song “My Vision” off the Seal IV CD. This 4 minute, 48 second track consumed 49.6 MB in its native “wav” format. Using the MP3’s highest resolution (best sound quality) of 320Kbps the song file size was reduced to 11.3 MB which is about 23% of the original file size. In the highest compression I would recommend, the song file size is reduced to only 4.5MB. That’s only about 9% of the original file size!
But you never get anything for free. The pitfall to reduced file size is reduced sound quality. Whether you can hear the difference depends on your playback system. If you are listening to your MP3 on most computer systems, it will be difficult to hear any difference between the 128Kbps bitrate versus the 320Kbps or even the uncompressed original CD. However, if you have playing back your MP3 on a high-end home or car system, you should really consider the higher bitrate MP3 encoding.
Downloading versus Ripping/Encoding
Typical MP3 available on the web are encoded at the 128Kbps bitrate. (Fine for PC or portable MP3 Players) But be very careful where you download your MP3s. The RIAA (Recording Industry Association of America) is cracking down on illegally downloaded MP3s. In January 2004, the RIAA filed 532 “John Doe” lawsuits against users it claims have been distributing music over peer-to-peer network such as Grokster, Imesh and Kazaa. To be safe, use a subscription based site for your MP3 downloads.
Ripping your CDs to MP3 is really where it’s at. Even at the highest resolution, you can store nearly 5 hours of high quality MP3 on a standard CD Rom. Lower your sampling rate to 128 Kbps and you can get over 12 hours of music. The clear advantage with ripping your own CD is the capability to encode at better sound quality, higher bitrates MP3s.
Playing your MP3s
Decoders first appeared and software downloads available for your computer. Today you can find decoders in portable CD players, dedicated MP3 players and now as feature of car audio source units. Most companies today offer MP3 player capability in their head units. There are also some interesting variations for MP3 like Kenwood’s Music Keg and Rockford Fosgate’s Omnifi and Alpine new head unit that can directly control a Mac Ipod MP3 player. All of these units offer large storage capability (20 GB and more) for weeks of continuous music stored in your vehicle.
Summary
Like it or not, MP3 is here to stay. Now that you’re the expert, take time to find out which products you carry have MP3 compatibility. The more you know about this technology, the better you will be able to integrate yourself into teh digital age.
