DAN DUGAN:
> > An interesting point, Rich. High-passing the input reduces the signal
>> level, and reducing the signal level into ATRAC reduces the need for
>> data compression.
WALT:
>This will only work if the signal level is not just reduced, but
>eliminated. The quiet stuff gets compressed along with everything else.
>So you would want to drop the signal by 90+ dB relative to your loudest
>signal I'd assume.
I thought perceptual coders like MP3 and ATRAC work with a "bit
budget." When the signal has a lower level it needs a smaller
bandwidth and thus less data compression. Maybe I'm wrong about this.
>I'm also not so sure about eliminating all the low end. That, too, is
>part of the natural ambiance. Even if it's a problem to record and play
>back properly.
I feel the same way, I'd rather preserve all the bandwidth my mics
can pick up--unless I'm having a problem with something that isn't
part of what I want, like freeway rumble or wind noise in the mic. I
often high-pass stuff later, but I want the option.
>It would actually make more sense to eliminate all the
>high end, as most don't really hear that.
ATRAC -does- eliminate the high end, which eliminates a lot of
bits--I see what appears to be a signal-dependent variable low-pass
around 16K.
-Dan Dugan
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