Just as the NYTimes’ Circuits section frequently belabors the obvious (its discovery of the miracles of USB a couple of weeks ago, for example), so this article points out that — surprise, surprise — an MP3 or an AAC from the iTunes store is not quite the same thing as a CD: Digital Domain: From a High-Tech System, Low-Fi Music
Love the iPod, but don’t jump too hastily to fill it with thousands of dollars of iTunes. The tracks are not carbon copies of the CD originals, but compressed versions. The smaller files are handy for speedy downloads, space-saving for storage and perfectly serviceable for listening through ear buds when riding on the subway. Not what you will want, however, when your desktop computer becomes the home jukebox and wirelessly sends these simulacra to the entertainment center in the living room.
Consumers find downloading instantly gratifying, but the company uses an extreme form of compression that takes a sample of the sound at intervals. The less information collected, the smaller the resulting file size – and the greater the loss of fidelity to the original. Apple has elected to use a compression standard that, to put the best face on it, creates an awfully small file.
This music lite is a response to the data transfer problems entailed in downloading the music that resides on anyone’s collection of CD’s. With about 10 megabytes needed to store one minute of music, albums eat up space quickly on a hard drive. Credit Apple for Step One: persuading the major music labels to make individual tracks available inexpensively, à la carte. By buying only the hit tracks and ignoring the rest of the album, storage needs drop by 90 percent.
Apple has yet to put into effect the second part of the ideal solution: distributing music that is compressed only temporarily, a process called lossless data compression. Before saving a digital song to the hard drive, software can shrink it in size by 50 percent or so just by using a shorthand notation that takes up a little less space for any repetitive patterns in the 0’s and 1’s. When the song is played, the software has all the information that it needs to restore it perfectly. With this, “you’ll get the full quality of uncompressed CD audio using about half the storage space.” The phrasing is from Apple’s own Web site, but, unfortunately, the company does not offer “true CD audio,” as it calls this, when you download music from the iTunes Music Store. It is available only when you traipse to the mall, buy the CD, and return home to copy it to your home computer with Apple software.
The company offers no explanation why “lossless” storage is desirable for tracks received through one source but not the other.
Really!? What possible reasons could there be for that?
Later: p2pnet’s take — Low-fi iTunes downloads
Slashdot: Are iTMS’s 128kbps Songs Worth Collecting?