Hi,
I am extremely interested in ATRAC, could you point me to the right
direction with a few links to various sites that's got the algorithm? where
did you get yours from? Any info would be great. I am hoping to gather more
info about it any maybe use it to do my dissertation next year.
Cheers,
Ambrose
=========================================================
Email : [EMAIL PROTECTED]
MD page : http://www.choyster.freeserve.co.uk/mdtrading.htm
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----- Original Message -----
From: wb <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: 12 March 2000 23:40
Subject: MD: ATRAC Type-WB
>
> Hi Everyone,
>
> I don't wanna interfere into the discussion whether or not ATRAC encoding
is
> possible on todays PCs (please no flames!!), but.... I have an ATRAC
> encoder/decoder running on my PentiumII-450Mhz (with good old Win95b). I
named my
> encoder/decoder ATRAC Type-WB (guess why!) Version 3.5-0.91 (this means
the
> psycho-acoustic model has been read out from a MD-Deck with ATRAC-Version
3.5 --
> MDS-JA3ES).
>
> The encoder eats about 75-80% of the CPU time and the decoder needs
20-25%. Both
> encoder and decoder are written in a high-lever language and have yet not
been
> opimized (no MMX and so on). The encoder even writes the bitstream in the
exact
> way a MD recorder would do, which means, if you write the encoded file
onto a
> MiniDisc, set the pointers in the UTOC correcly and put the disc into a MD
player
> it will play. About 15% of the CPU time is used for the QMF and the type
> conversion (float2integer) -- unbelievable; 10% is needed for the bit
> packing/unpacking and the fast cosine transforms. A lot of improvement
could be
> done here since I use the FCT algorithm for the DCT type I, but ATRAC uses
DCT
> type IV. Anyway. My encoder version (0.91) has still some problems with
the
> BlockSize decision.
>
> Since sony has registered the name "ATRAC", I am already thinking about a
new
> name for my encoder/decoder. How about "CARTA" (pronounced "ATRAC" -- if
you read
> it from right to left! :) Any suggestion are welcome! BTW: Everybody with
some
> math knowlege can build their own en/decoder. All the information you need
is
> availble on the net (no kidding!)
>
> wolfgang
>
> ps: I now know why Sony announce their new gear (MDS-JB940) so early.
Well, I
> somehow have to prepare my parents about what my wishes for next chistmas
are!
> Although, if I remember correctly, my Mom told me if I ever come home with
new MD
> stuff, I will be kicked out of the house (that I wouldn't really care...
well
> yes, I would) and she will throw away all my MD stuff (that I surely WOULD
> care!!)
> ----------------------------------------------------------------------
>
>
> Stainless Steel Rat wrote:
>
> > * Eric Woudenberg <[EMAIL PROTECTED]> on Sat, 11 Mar
2000
> > | I'm missing something. Didn't I demonstrate that MP3 (a more complex
> > | coder than ATRAC)
> >
> > 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.
> >
> > ATRAC has a much more sophisticated time-frequency distribution model,
one
> > that uses the same psychoaccoustic model as the bit reduction algorithm.
> > 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.
> >
> > | runs at 3X realtime on my 500MHZ desktop machine? Do you still somehow
> > | think ATRAC would be slower than realtime on such a machine?
> >
> > For sound quality as close to ATRAC 4 as MP3 is capable of achieving,
yes.
>
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