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| Original
specifications |
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Super
Audio CD |
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SACD
original specifications (cont.)
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So
far, only the SACD format fulfils all above
requirements, particularly the fourth one which
ensures compatibility of high-density discs with
existing CD-players. Such a compatibility, which is
required in view of the 500 millions CD-players
currently in the market, is guaranteed thanks to the
hybrid disc structure of the SACD disc, which
includes a 'CD Red Book' compatible reflective
layer. Conversively, it is obvious that the 10
billions Compact Discs in the market have also to be
accepted by new high-density audio players.
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Regarding
copyright, SACD has opted for a fully transparent
Digital Watermarking, which can carry disc IS, ISRC
and SID codes. It is also easy to differentiate
legitimate from pirate copies of SACD discs, thanks
to the visible and invisible Digital Watermarks,
which, furthermore, can not be easily removed.
Another advantage of Digital Watermarking is finally
the possibility to accommodate
imbedded 'eyes'.
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The
difficulties of DVD-Audio to come up with a good
copyright protection system has also been useful to
promote SACD's Digital Watermarking as one of the
most reliable anti-piracy measure.
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One
of the most attractive feature of SACD remains of
course its very high audio quality, which seems to
be unequalled today in digital audio. With a
frequency response from DC to 100kHz, plus a dynamic
range greater than 120dB across the audio band, SACD
can reproduce the original music tracks in their
tiniest details, whatever the sound mode, stereo or
multiple channel.
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As
a summary, SACD meets all 13 requirements of the
ISC's specifications for a new high-density digital
audio format, thanks to 5 main technologies :
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| 1. |
Hybrid disc
technology makes SACD discs compatible with
both SACD and conventional CD players. Such
discs are made of two layers : a normal CD
layer and an additional semi-transmittive
high-density layer.
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| 2. |
Direct Stream
Digital (DSD) is used to convert an
original audio waveform in a 1-bit
representation using a 2.8224MHz sampling
frequency. This leads to a sound quality never
achieved by analogue or digital audio players
so far.
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| 3. |
Super Bit
Mapping Direct (SBMD) is a downconversion
system which provides the best sound quality
in any current digital formats (including
16-bit / 44.1 kHz) from an original DSD signal
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| 4. |
Direct Stream
Transfer coding has been developed to
increase data capacity on the optical disc, so
that can be combined 2-channel stereo,
6-channel audio, plus additional text,
graphics and video information on a
single-sided 12cm disc.
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| 5. |
Digital
Watermarking is one of the most reliable
copyright protection and anti-piracy system.
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