MP3: The Bare Facts

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Tired of swapping CDs in and out of your stereo to play your favorite songs? While buying a 50-disc changer might mitigate this annoyance somewhat, it's still a pain to figure out what song is on which track on which disc in the changer. The solution to this problem is staring you right in the face. With your Mac, your CD collection, and a handy technology called MP3, the days of CD-shuffling will soon be behind you.

"Another for lunch, and a sensible dinner": MP3 encoding seriously slims down bloated audio files.

Using the MPEG Layer III (thus MP3 ) encoding algorithm, you can compress a 34MB raw sound file to a 3MB MP3 file, which makes storing and playing back huge song collections on your Mac entirely possible. (see before&after.gif) This amazing file squeeze does come at a cost: you need a reasonably fast Power Mac to play MP3s and while MP3 files are promoted as "CD-quality," some quality is lost in the compression process. The level of quality achieved depends in large part on the bit-rate at which the audio data is encoded -- the higher the compression, the lower the bit-rate and sound quality. 128 kbps is a fairly common bit-rate, though larger 168 kbps are also popular. Less popular MP2 files utilize the less complex Layer II encoding scheme but achieve similar compression and quality to MP3 at a 128 kbps bitrate.

Besides the technical mumbo-jumbo, there are some legal issues involved. Making MP3s of songs you own on CD or of audio files you created yourself is perfectly legitimate; however, trading MP3s of copyrighted music is akin to selling bootleg Tupac tapes on the street corner. (Well, maybe not that bad.) While RIAA (Recording Industry Association of America) agents probably won't break down your door the second you download or send an MP3 file, record labels have been known to shut down popular MP3 sites on the Net. With those caveats in mind, here's a step-by-step look at the MP3 process.

***Step One: The Great Rip-Off

First, you need to get the audio data off of your CD onto your Mac. Ripping programs will convert a track off of any ordinary audio CD into a very large audio file (AIFF or PCM) on your hard drive. The freeware Track Thief does an impressive job of extracting audio from CDs as AIFF files at the maximum speed your CD-ROM drive can handle. Other ripping programs include the Toast Audio Extractor component of Adaptec Toast, the freeware oldie SoundSmith, and the built-in extraction routines of MPecker Encoder and MPEG Audio Creator.

***Step Two: Small is Beautiful

Once you have the audio files on your hard drive, it's time to slim them down through the magical MP3 encoding process. Two popular MP3 encoders are the freeware MPecker Encoder and the recently released commercial Xing AudioCatalyst. Both provide CD ripping and MP3 encoding; AudioCatalyst also boasts a feature called Variable Bit Rate Encoding (VBR) which supposedly results in "higher quality sound in often smaller files." While we did not test the validity of this claim, MP3 files that use VBR will play incorrectly on older MP3 players, so AudioCatalyst purchasers should be sure to download the latest VBR-compatible versions of MacAmp, SoundApp, or MPEG Audio Realtime Player. The shareware MPEG Audio Creator is a speedy, easy-to-use CD ripper and MP2 encoder worthy of your consideration. Encoding time depends on the speed of both your computer and the encoding software; on a G3 Mac, MPecker Encoder can encode audio files to MP3 at better-than-realtime speed (meaning a second of audio takes less than a second to encode).

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