MP3 on a Macintosh

Disclaimer: any opinions expressed in this article are those of its author ( comartin@wicc.weizmann.ac.il ) and do not purport to represent Weizmann Institute of Science policy.

What the PC is MP3?

The short answer: MP3 stands for MPEG (Motion Picture Experts Group) Layer 3. It is an audio compression format that on average yields near-CD quality at one-tenth the size. That is: a regular CD, which holds about 74 minutes of uncompressed music, can hold something like 12-13 hours worth of MP3 files.
MP3 is a so-called "lossy compression" algorithm, which (like JPEG for pictures) takes advantage of the limitations of human perception to achieve very high compression ratios (10:1 is common for sound). This stands in contrast to so-called "lossless" algorithms, ike GIF for pictures, as well as such popular file compression formats as ZIP on PCs, gzip on Unix systems, and StuffIt on Macintoshes. Lossless algorithms merely exploit repetition, redundancy,... in the original file to arrive at a compressed representation, but do preserve all the details of the original. The upshot is that they generally achieve much lower compression ratios (2:1 or 4:1) than lossy algorithms.
For the long answer, check out the  MP3 Technical Info and  FAQ at the  Fraunhofer-Gesellschaft.

Is MP3 encoding legal?

No more or less than taping. That is, encoding one's own CDs for personal use is perfectly legal, but selling MP3 files encoded from commercial CDs, without paying royalties, isn't.

Are there any good encoders for the Mac?

A detailed review can be found  here . The two best general-purpose encoders for Macintosh appear to be, ex-aequo, Proteron N2MP3 and Xing AudioCatalyst . Both programs are commercial: AudioCatalyst can be downloaded upon online payment, while N2MP3 comes as an evaluation version that will let you encode 20 tracks per installation, and preface every track with a spoken "Encoded by N2MP3" message. (Upon online payment of the registration fee, one receives a password to remove these limitations.) Macromedia SWA Export Xtra (based on licensed Fraunhofer code) does a great job as well, but is quite slow even on G3 machines. It is a freeware plug-in for the expensive Macromedia Director multimedia software, but Johan Lindvall developed a freeware  hack that allows one to use the plug-in without Director.
 Casady & Greene SoundJam MP is a popular commercial encoder/player combination, with lots of fancy bells and whistles like graphic equalizer, spectrum analysis while playing, etc. Unfortunately, when it comes to the music itself, it does a comparatively poor job, as witnessed both by the above review and yours sincerely. Stop Press Jan 17, 2000: recent versions of SoundJam's encoder (1.5 and above) are reported to be dramatically improved in quality, although I have been unable to verify this myself. Recently, a Macintosh port of the GNUware Blade Encoder has been brought out. Based on ISO reference encoder. User interface as primitive as it gets, but can't complain about the price. Author claims that quality should surpass that of Fraunhofer engine at 160kbps and higher, since the Fraunhofer algorithms are optimized for 128 kbps and lower. A detailed review found it to be distinctly inferior to N2MP3 and AudioCatalyst, as well as to never versions of SoundJam run at high bitrates (160 kbps and above). A newer public domain encoder called LAME (Lame Ain't an MP3 Encoder) appears to be a better bet if you want freeware: I will post a link for a Macintosh binary as soon as I can get hold of one. Stop Press March 6, 2000: you can download one called CocaCoda, albeit with a Japanese language interface: an English Language Patch is available. Neither LAME nor Blade can encode directly off CDs, but you can copy them as AIFF files first using Track Thief...

What about MP3 players for Macintosh?

There are two considerations: playback quality and processing overhead. Last but not least, there's cost.
  • One useful tip if you do decide to get MacAST full version: in the Preferences, go to the "buffer memory size" and crank this up as high as possible (1024 K is the maximum, I think) to reduce skipping during heavy disk activity.

  • But how does it sound? Can you hear the difference?

    I am a listener of very wide-ranging musical tastes (as long as the music is "nonobvious") and did extensive informal testing with both N2MP3 and SoundJam, using various kinds of music. (Since I like to have music going while working, and the CD player on my Powerbook G3 skips whenever I type with my usual force --- having learned typing on a mechanical typewriter --- MP3 is my default audio entertainment.) Why no classic Beatles, Rolling Stones, etc? Quite simply: because these records will sound good with just about any halfway decent encoder, since they were produced and mixed to fit the limitations of equipment with specifications that sound laughable by today's standards.
    The performance at 128kbps of SoundJam on some of these tracks (particularly the Metallica) was pathetic. N2MP3 produced decent encodings of just about all of them at 128 kbps, stereo, "high" quality setting. The Tangerine Dream had to be redone at 160 kbps. I could get acceptable quality for the Shostakovitch at 64 kbps mono (note that for mono recordings, this is equivalent in quality to 128 kbps stereo!).
    One important factor are also the quality of your audio speakers and/or headphones. If you hooked your computer up to a quality hifi chain with ditto speakers, it might be worth the extra disk space to encode at 160 kbps or even 196 kbps, or to go for VBR encoding (see below). If you are using typical "multimedia" speakers, this is generally a waste of disk space.
     

    What do the settings for encoding mean?

    I will take the example of N2MP3, my favorite encoder — but all good encoders will have most of these settings.

    Miscellaneous tips

    If you are using external "multimedia speakers", crank up the sound volume on your Mac and turn down the volume on the speakers to compensate. This will minimize noise and hiss from the usually rather low-fi amplifier in these speakers.
    If a CD starts skipping during copy and/or encode, don't panic. Usually the problem can be remedied by cleaning the CD with soft cotton and water. (Be gentle.) Tricks for repairing more persistent skips can be found at the  Learn2 site.
    Using Track Thief, you can save several CD tracks together as a single AIFF (uncompressed CD sound) file, which you can then encode at one go. I tend to do this for albums I like to hear at one stretch (say, Genesis' The Lamb lies down on Broadway, Donald Fagen's The nightfly, Chick Corea's Children's songs,  Klaus Schulze's Mirage) or for multi-part classical pieces (e.g. all movements of a Beethoven piano sonata as one MP3, or a prelude and fugue pair in J.S. Bach's Well-tempered clavier).
    One "audiophile" solution that costs about the same as a pair of good computer speakers and gives much better quality is to buy a pair of Sony [or other quality brand] wireless headphones. (We paid $65 for ours at the duty-free in the airport; presumably they'll be a bit more expensive around the country.) Since the base unit has its own pre-amp, you can plug that straight into the computer. A bit of fiddling with the volume controls on computer and headphones (as always, the stronger the signal into the amp, the better the signal-to-noise, but the weaker, the less distortion --- the optimum is somewhere in the middle) and off you go.

    Links

  • MP3 music software for Macintosh
  • Comparative review of MP3 encoders for Macintosh
  • Another such review; another relevant site
  • NEW MacDigitalAudio.com site
  • NEW DropMP3, a brand-new implementation of the (anything but) LAME MP3 encoder
  • Another such site
  • MP3meta search engine.
  • Another MP3 on a Mac page.
  • Comments? Write  comartin@wicc.weizmann.ac.il

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