[Speex-dev] ultra wide band packet questions
Jean-Marc.Valin at USherbrooke.ca
Sat Sep 24 03:25:32 PDT 2005
Hi (sorry for the long delay),
> So I have started finally fiddling around with Ultra-wideband mode.
> It appears to be very similar in operation to Wide mode, except that
> when peering into the packet structure it looks like (and these are
> kind of questions as much as statements here):
If you're using ultra-wideband, be aware that it can sometimes sound
worse than wideband (depends on the input and who's listening).
> 1. update rate 0 is not used in UWB- only 1-4?
It's not an update rate, it's a submode.
> 2. The total bits used for each UWB update rate seem to be as follows:
> 0:36 bits (a guess)
> 1:72 bits
> 2:148 bits
> 3:224 bits
> 4:384 bits
Only submode 0 is valid for UWB, i.e. an SBR-like high-band.
> Which leads to my follow up- it was hard for me to determine why in
> some cases UWB was 36 bits per packet more and other cases only
> 32 than WB mode. I couldn't find anything in the code that could
> account for the difference. The only thing I could find didn't
> account for
> all 32/36 bits. Any pointers appreciated...
Maybe this just has to do with the rounding of bytes (e.g. if there's
only 4 bits used in the last byte).
Jean-Marc Valin <Jean-Marc.Valin at USherbrooke.ca>
Université de Sherbrooke
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