From: Stainless Steel Rat <[EMAIL PROTECTED]>
To: MD-L <[EMAIL PROTECTED]>
Sent: Sunday, March 12, 2000 6:16 AM
Subject: Re: MD: Sony's new Internet Audio Recording Interface
> Whosoever has told you that is full of crap. At the fundamental level,
MP3
> (MPEG-1 Layer III audio) has a pathetic time-frequency distribution model.
> At lower bitrates, 128Kbps (allegedly "near-CD quality) and below, audio
> signals with lots of high and low frequency sounds but relatively little
in
> the middle get... "cropped" is the best way I can describe it. When the
> time-frequency block is full, any remaining signal gets thrown away,
> whether or not it is significant. I understand that Prince's "Raspberry
> Beret" is an "MP3 breaker" for this reason, but I have never made the
> comparison personally.
There are many different approaches to encoding MP3 and what you have
discribed is not the case for all of them. The quality of an MP3 can vary
considerably from encoder to encoder at the same bitrate, and a song which
breaks one encoder can sail through flawlessly on another. I know for a fact
that Xing is hopeless with military brass-band type music (it made a mess of
the theme to Monty Pythons Flying Circus even at 160bps) yet Fraunhoffer
loved it (near perfect at 112bps!).
> ATRAC has a much more sophisticated time-frequency distribution model, one
> that uses the same psychoaccoustic model as the bit reduction algorithm.
ATRAC is also designed to be an on-the-fly encoding system - MP3 is not.
> The result is that time-frequency blocks are allocated based on "density".
> Frequency ranges with more sound get more bandwidth; those with less sound
> get proportionally less bandwidth.
There's no reason why an MP3 encoder couldn't take this approach either - I
think LAME may even do just that!
Magic
--
"Creativity is more a birthright than an acquisition, and the power of sound
is wisdom and understanding applied to the power of vibration."
Location : Portsmouth, England, UK
Homepage : http://www.mattnet.freeserve.co.uk
EMail : [EMAIL PROTECTED]
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