> > >>> http://www.minidisc.org/atrac_breakdown.html
>
> this page. It is clearly not an ATRAC effect. But is not just simple clip=
ping.
> It is a special overflow effect that can occur in digital signal processo=
rs
> when the signal level exceeds the maximum value that a fixed point intege=
r
I have a comment on this, as I have observed and investigated this
phenomenon when getting "overs" in my own recordings made with Sharp
recorders.
It is indeed the result of a digital number rolling over, and
the highest bit falling off the end. Eg, imagine if you could represent
the amplitude of a signal for any sample between 00-99, and increased to
100 -- this would be represented as "00."
While this waveform sounds genuinely terrible if played as is, it's worth
mentioning that it is in fact, for someone with patience and the interest,
actually a hidden gift.
The gift is that if you edit the waveform in a greater than 23 or 32 bit
"space," you can in a straigthforward way exactly restore the un-rolled
state -- in the example above, simply add the extra "1" back on.
The result is that your gear is effectively > 16 bit resolution (in
representation), as long as the "overs" are only on momentary transients
(and hence identified contextually).
I don't recommend this as a recording strategy though as this is quite
laborious in practice. It would be straightforward I think to write an
algorithm to do this, but by hand it's a drag -- so I actually usually
just "eyeball" in the corrections by sketching a nicely rounded peak... :)
A final comment -- doing direct, unedited transfers to CD, I have noticed
that some CDs players' D-A process "catch" this and correct it on playback
themselve -- I imagine they do so as a last-ditch effort to compensate for
a bad read. I've actually come close to sending out CDs that had this
problem as result -- and learned to audition everything in the studio! :)
best,
aaron
http://www.quietamerican.org
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