On Mon, Sep 27, 1999 at 03:20:25PM +0200, Ralph Smeets wrote:
>
> [EMAIL PROTECTED] wrote:
> > >From my memory (its been years since I actually *knew* any of this),
> > the CD error correction system is two level. First, it does error
> > correction and can precisely reconstruct the data if the errors are
> > within some threshold (similar to MD, I suppose). Its only if the error
> > correction fails that it will then "guess" (interpolate) at the signal.
>
> You're correct here. But the error correction system only accepts single bit
> errors...
> Ie, guessing mode is entered very quicly. (A dust particle is sufficient!)
This could well be so, last I remember reading about this stuff was in the
early-to-mid 80's (while CD was still quite new). Could you point me to
any on-line info on the subject (I'd like to dust-off the cobwebs)?
>
> > > the error-correction system in a MD-player is based on storing
> > > extra data that makes it possible to reconstruct excactly the original
> > > signal! This is where MD is far superior).
> >
> > I am not familiar with the MD error correction system, but I'm quite
> > certain that CDs do this as well as stated above (though perhaps not as
> > well as MD, afterall, MD is about a 10-year new technology).
> >
>
> AFAIK, the ATRAC error correction takes place before 'decompression'. If
> I understood the IEEE-ATRAC document correctly (Eric please help me out),
> MD has no guessing mode. Ie, It can either correct the error or you get
> a moment without sound.
It makes sense the the error correction would occur first. Certainly
seems that you would want an error-free signal to decompress. In fact,
I would guess that errors that made it through would royally screw up
the decompression. Also, wouldn't surprise me that they were forced to
make the error correction more robust than audio CD's partly (at least)
for this reason. (Also, it seems likely that interpolation of missing
parts, like they do with CD, would work either.)
--
Bob Willcox Don't tell me that worry doesn't do any good.
[EMAIL PROTECTED] I know better. The things I worry about don't
Austin, TX happen. -- Watchman Examiner
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