MP3: The Definitive Guide

The Codecs

In almost all cases, the alternatives to MP3 also use some form of perceptual codec, as described in Chapter 2. That means that all of these formats achieve their compression by discarding or reducing the amount of data representing inaudible sound (though the question of whether any sound is truly inaudible is still up for grabs; some diehard audiophiles maintain that even inaudible sounds contribute to music’s overall atmosphere).

Note

This section only covers alternative audio compression schemes and file formats; there are many noncompressed formats that aren’t really of interest to us here.

Throughout this discussion, keep in mind that if you decide to test some of these alternative codecs or formats, most of which claim smaller file sizes and higher quality, you’re not going to get smaller files at the same bitrate. In other words, regardless of what format you use, 128 kbps means what it says: For every second of music, you store ~128,000 bits of data. The question is, how much quality can you get out of that much data? What you really want to discover is how low of a bitrate can you use and still get “CD quality” or “near CD quality” sound. Where there’s money and improvements to be made, there’s fierce competition. Don’t expect it to let up anytime soon; anything could happen between now and next year.

AlbumDirect

At the time of this writing, it was too early to tell exactly what IBM has in store for us on the digital music distribution front. What we do know is ...