[vorbis] some more Spec questions

[Segher Boessenkool]

Sebastian Gesemann wrote:
> - AFAIK Vorbis uses MDCT transforms which will result in 'spectral-
>   vectors' of the length 1024 (for long blocks) and 128 (for short
>   blocks) at 44kHz, so I expected the two 4-bit exponents in the
>   identification header to be 7 and 10, but I found 8 and 11 in
>   my Oggs. So the "blocksize" values correspond to the nominal
>   window-length instead of the length of the 'spectral-vector' ??

Assuming windows are always exactly 2:1 overlapped, yes.  This is
an oversight, but just divide by 2 and you'll be fine.

>   I find it a bit confusing and inconsistent. (Compare to 'vorbis-
>   spec-intro.html': 64...8192 samples/frame)
>   I suggest adding a note for clarification.

Why don't you write a patch for the doc?  :-)

> Floor 0 format - header decode
> ------------------------------
> - Step 7: how could any of those values be less than zero
>   if i read them as unsigned integers ?

If you don't quote the relevant part of the doc, I can't answer this,
sorry.  Try again?

> Floor 0 format - curve computation
> ----------------------------------
> - What is [n] in context of the 'map_i = minimum { ...'-

Same here...

<p>Segher

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