Hardware Reference
In-Depth Information
Note
When extracting (ripping) music from CDs, the default format is uncompressed WAV;
however, other compressed formats such as MP3 can be used as well. Because WAV files
match the high 44.1KHz sampling rate used on the CD, you have 176,400 bytes per second
of sound information, which means 1 minute of music consumes nearly 10.6MB worth of
space on your hard drive. MP3 compression can reduce that by a factor of 6 or more, with
little to no perceptible loss in quality.
“For Music Use Only” CD-R/RW Discs
According to the Audio Home Recording Act of 1992, consumer CD recordable drives
and media sold specifically for recording music are required to have specific safeguards
against copying discs, mainly SCMS. That means these recorders can make digital copies
onlyfromoriginal prerecorded discs. Youcancopyacopy,butinthat case, thedata being
recorded goes from digital to analog and back to digital on the second copy, resulting in a
generational loss of quality.
The media for these recorders must be special as well. They work only with special discs
labeled “For Music Use,” “For Audio,” or “For Consumer.” These carry the standard
Compact Disk Digital Audio Recordable logo that most are familiar with, but below that,
as part of the logo, is an added line that says “For Consumer.” These discs feature a spe-
cial track prerecorded onto the disc, which the consumer music recorders look for. Built
into the price of the AHRA-compliant media is a royalty for the music industry that this
trackprotects.Themediacostsabout20%-30%morethanwhatregularCD-R/RWmedia
costs. If you try to use standard non-AHRA-compliant CD-R/RW discs in these drives,
thedriverefusestorecognizethedisc.Thesemusicdevicesalsorefusetocopydatadiscs.
Note that this does not apply to the optical drive you have installed or attached to your
PC. It does not have to be AHRA compliant, nor does it need to use AHRA-compliant
“For Music Use” media, even if you are copying or recording music discs. Additionally,
you can make digital copies of copies—the SCMS does not apply, either. The bottom line
is that you do not have to purchase AHRA-compliant discs for the optical drives in your
PC.Ifyoudopurchasesuchdiscs,despitethe“ForMusicUseOnly”designation,AHRA-
compliant discs can be used in your optical drives just as regular CD-R/RW discs can be
used for storing data. The extra information indicating AHRA compliance is simply ig-
nored.
CD Copy Protection
Worries about the public copying of software and music CDs has prompted the develop-
mentofcopyprotectiontechniquesthatattempttomakethesediscsuncopyable.Thereare
different methods of protecting software CDs versus music CDs, but the end result is the
