James Jarvie <[EMAIL PROTECTED]> writes:
> What is Scale factor edit?
The article http://www.minidisc.org/mj_ja3es.html is instructive.
ATRAC (and other modern coders) store audio in the frequency domain.
The samples are stored as floating point numbers, with an exponent and
a mantissa. The so-called Scale Factor is the exponent, and has a
range of 0 (1?) to 16, yielding final sample values in the range of 0
to -96dB.
Scale factor edit is a function which changes the volume level of
previously recorded audio by changing all the scale factors in each
soundgroup. It's a much cheaper operation computationally than
decoding the full waveform, scaling it, and then recoding it.
If I understand the operation correctly, the one minus is that there
are only 16 scale factor values, so you would only have control over
volume level in 6dB steps (if they don't touch the mantissa). However
since I've never tried the feature I don't know for sure if that's a
problem or if they have some way around it.
(The one plus side is that with that level of courseness, you should
be able to losslessly "undo" a track wide level change at a later
date if you remember how much you altered it).
Rick
p.s. corrections from folks who know more are always welcome!
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