[Sonnova]

On Mon, 10 Dec 2007 15:41:10 -0800, Arny Krueger wrote
(in article ):

"MC" wrote in message

"Doug McDonald" wrote in
message ...
Arny Krueger wrote:

It is true that the essence of perceptual coding is
eliminating tones that will not be heard anyway,

This is only true at very low, very poor quality,
bitrates, and possibly for very low level high frequency
content.

For good encoders (such as LAME VBR at = 160K) no
"tones are left out". The only "perceptual" feature
is how the encoder distributes highly colored noise.
At very high bitrates the noise becomes pretty much
high frequiency rolled off white noise.

I tested this with the FHG pro MP3 coder and found that the essence of the
loss due to lossy coding was something like a loss of dynamic range. Sort of
what like what analog tape or the LP format do all the time. Even the
quantities were similar. The rise in background noise looked something like
pink noise.

And I'll bet that it rides the envelope of the music as the dynamics change,
doesn't it, causing a nasty breathing sound?

In fact I suppose it can be said that a high proportion
of the "fine detail," in either images or sound, is
actually noise and can be dispensed with. Right?

In moderation, either the ear or eye can be fooled into perceiving no loss
of details.

As long as that same sensory apparatus doesn't notice or mind the artifacts
which accompany "being fooled", I'm sure that's true.