seanadams;193800 Wrote: 
> I don't think so. Since this a red-book specific (and obsolete) feature
> I would recommend doing the deemphasis when you rip. Some tools can do
> it.
Emphasis is not red-book specific.  It is supported by other devices,
such as minidisc recorders and the F1-type digital adapters which are
defined by an EIAJ standard.  As a matter of fact, the Sony
PCM501/601/701 record with non-defeatable pre-emphasis, however the
playback automatically switches in de-emphasis according to the
emphasis bit in the recording.

Emphasis, when applied correctly in digital audio, does exactly what it
was intended to do, that is reduce the noise floor.  Since random noise
is equal-energy-per-unit-bandwidth, while hearing is
equal-energy-per-octave, each successive octave having twice the
bandwidth, randim noise has most of its energy in the higher octaves. 
Usually random audio noise is called hiss.  By boosting the higher
frequencies during recording or transmission (pre-emphasis) they may be
reduced in a complementary manner during playback or reception, thereby
reducing the random noise introduced in the recording or transmission
channel.

If de-emphasis is done in the digital domain, the result must contain
more bits of precision if the S/N benefit is to be realized.  That is,
by de-emphasizing a 16-bit CD to a 16-bit file, you've just lost the
benefit of lower noise floor.  Therefore, CD players that do digital
de-emphasis often have 20- or 24-bit paths after de-emphasis to
preserve the lower noise floor.

De-emphasis probably fell out of favor because many early CD players
used inaccurate analog R/C de-emphasis networks.  This is no longer a
problem as CD players almost universally do de-emphasis digitally. 
However, now we have a new problem, as computer audio has become a
larger player.  Emphasis was not originally important in computer audio
and thus was ignored by many (defacto) standards and most computer
hardware.  It has only become important as CD audio has merged with
computer audio.

Is emphasis useful?  For most popular music, probably no, because the
96 dB S/N radio afforded by 16-bits with no emphasis is more than
enough.  Sadly. many popular recordings today are jammed up into the
top few bits, not exploiting anywhere near what the CD can offer
without emphasis.  Emphasis would make these recordings worse, jamming
them even harder against the top.  However, classical recordings with
wide dynamic range can benefit from emphasis.  Maybe not as much as
HDCD, but emphasis is an intermediate step that can be decoded by all
CD players, whereas HDCD can only be decoded by a handful.  And, if you
want to get the best out of an emphasized CD on your Transporter, just
apply the de-emphasis curve using your favorite sound editor (mine is
Cool Edit) and write the result to 24-bit to preserve the benefit of
emphasis.


-- 
Timothy Stockman
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