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ATRAC (Adaptive TRansform
Acoustic Coding)
(dB)
+20
High
0
-20
Ear
sens.
-40
-60
Low
20 50
100
500
Audio
Low
freq.
Sound skip guard memory
During normal
During
playback
vibration
UTOC (User Table Of Contents)
UTOC
Music data
The MD (Mini Disc) has half the size of the CD but can record data for
the same period of time. This has been made possible by the newly
developed ATRAC (Adaptive TRansform Acoustic Coding), which
compresses data by cutting the audio components that are inaudible to
the human sense of audition. This technology reduces the recorded data
to about 1/5 the original data quantity and enables recording/playback
of data for up to 74 minutes.
5k
10k
15k
1k
(Hz)
High
The sound skip guard memory stores some data of the played track so
that the played audio does not skip due to vibration during MD (Mini
Disc) playback.
stop
In case the optical laser cannot read disc signal due to vibration, the
actually reproduced audio is not interrupted because the data stored in
the guard memory is available.
The recordable MD (Mini Disc) contains the recording of UTOC (User
Contents
Table Of Contents) in addition to music data itself. The UTOC includes
1st tune...
2nd tune...
the information on the positions the tracks are recorded, markings
3rd tune...
between tracks and order of tracks, so tracks can be searched quickly by
referring to it. The editing operations consist of altering the UTOC
contents and the actual music data does not need to be re-recorded.
35
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