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SDMI
SDMI which stands for Secure Digital Music Initiative, is a forum that consists of over 130
companies in the fields of recorded audio content, computers, and consumer electronics,
dedicated to developing an integrated method of copyright protection technology that can be
used worldwide.
SDMI is working to create a framework for preventing improper usage of audio files and to
promote legal music distribution services. The copyright protection technologies “OpenMG” and
“MagicGate” are based upon the SDMI standard.
“Check-in/Check-out”
Check-out is to transfer music files from a personal computer to an external device/media (such
as Network Walkman). Returning checked-out music files to the same computer is to check-in.
(You cannot move checked-out music files to another computer.)
You can check-out a music file, check it back in, and then check it out again an infinite number of
times. The SDMI rules provide that up to four copies of a music file can be checked-out at one
time. OpenMG employs a method whereby three copies of a song can be checked-out
simultaneously, while the fourth copy is maintained as a “master” on your PC. If three copies of
the same song are checked-out at a given time, one copy of the song needs to be checked-in to the
computer in order to create an additional check-out.
Bit rate
Indicates the data amount per second. The rate is reflected in bps (bit per second).
In OpenMG Jukebox, the bit rate for recording an audio CD or converting MP3 and WAV format
audio files into ATRAC3 format can be chosen from 132 kbps/105kbps/66kbps. 105 kbps means
105000 bits of information per second. If the bit rate is large, that means a large amount of
information is used to play music. Comparing music of the same format, a 105 kbps data offers
better sound quality than 66 kbps data, and 132 kbps data offers better sound quality than 105
kbps data. However, audio files in formats such as MP3 have different encoding methods, and
thus sound quality cannot be determined by simply comparing the bit rate.
Glossary (continued)
