[EMAIL PROTECTED] wrote:
>
> * "Magic" <[EMAIL PROTECTED]> on Wed, 08 Mar 2000
> | Fair enough, however, modern DIMMs are much much faster than the RAM you
> | would find in the MD. The processor is also much much faster. If it takes me
> | 3 instructions to do what the ATRAC chip does in 1, that means I can do it
> | at the same speed if my processor does instructions in 1/3 of the time.
>
> You are comparing apples and eggs. The ATRAC DSP does not work the same
> way a general purpose processor works. The measurement is not how many
> instructions they can process per second; the measurement is how much data
> they can process per second. And the fact remains that a dedicated DSP can
> process more data per second than any current generation desktop PC.
that's my whole point. DSPs are designed to do 'number crunching'. I've
been involved in the functional verification of the ST100 DSP core. Our
team (including me) verifies also the design of the SH4 (The CPU you'll
find in the DreamCast). DSP and CPU architectures are completely different.
DSP's are optimized to keep the data flowing. However their are NOT designed
to handle control tasks (Ie, handle interupts etc.). A CPU however is a very
general purpose processor that has to be able to loads of things.
Compare it with cars. If you look at a particular price-class, you'll find a
wide range of cars. Varying from sporty cars to mini-vans. The sports-car will
do one thing very well: Going Fast. The mini-van however will transport a lot
for you, but they won't go very fast.
If you build a DSP for one special purpose, you'll be able to optimize the
core even more. Looking at the evolution of ATRAC, I believe that until the
birth of ATRAC 3.x, Sony was unable to design an ATRAC encoder that was fast
enough to do the encoding 'unoticable'. Why do I come to this conclussion,
simple:
- Sony knew how they could improve their algorithm and therefore build a
decoder that could handle future encoding schemas.
- ATRAC 3.0 and higher implements 3 frequency bands that can be modified. Ie,
they aren't fixed like ATRAC 1 and 2. This requires a lot more processing
power.
Cheers,
Ralph
--
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Ralph Smeets Functional Verification Centre Of Competence - CMG
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"For many years, mankind lived just like the animals. And then
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We learned to talk."
-- Stephen Hawking, later used by Pink Floyd --
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