[CELT-dev] Variable frame size and API changes

[Bob Bang]

A 51.2kHz rate could be done with most ADC's, however, if a digital output
was being used, a sample rate converter would be necessary to match the
rates to external components. (for audio networking, etc).

I understand your argument, and it can be done. It just doesn't seem like an
optimal solution.

Regards

PS. I think the CELT community is great. And having direct communication
with the developer is a wonderful asset. Thank you for your time and energy.


2010/5/19 Jean-Marc Valin <Jean-Marc.Valin at usherbrooke.ca>

> Quoting Bob Bang <bob.bang2 at gmail.com>:
> > in regards to your oversampling idea, the extra processing required may
> > nullify the gains from using DSPLIB over kissfft.
>
> I'm not suggesting resampling, but actually doing the native sampling at
> 51.2
> kHz.
>
> Cheers,
>
>   Jean-Marc
>
> >
> > To be honest, I have not measured the MIPS difference between DSPLIB and
> > kiss FFT, I will try to do that sometime soon to see how much of a
> > difference the intrinsic libraries make. Do you have those numbers
> already?
> >
> >
> >
> > 2010/5/18 Jean-Marc Valin <Jean-Marc.Valin at usherbrooke.ca>
> >
> > > Hi Bob,
> > >
> > > A few questions/comments:
> > >
> > > 1) It may be possible to use the TI DSP for all of the radix-2 steps in
> the
> > > FFT
> > > and then only apply the radix 3 and 5 in C.
> > >
> > > 2) I assume that the sampling is done on the TI chip, so couldn't you
> just
> > > configure it to work at 51.2 kHz? This would produce frames that are
> powers
> > > of
> > > two and the resulting bit-stream would be perfectly compatible with a
> > > decoder
> > > running with the same frame duration (hence 15/16 the actual number of
> > > samples)
> > > at 48 kHz.
> > >
> > > Cheers,
> > >
> > >   Jean-Marc
> > > Quoting Bob Bang <bob.bang2 at gmail.com>:
> > >
> > > > Hello Jean-Marc, I appreciate you taking our feedback in this change.
> > > >
> > > > I would be against this new input frame size change as I am
> developing on
> > > > the TI 55x platform.  On this platform it benefits to use the DSPLIB
> > > which
> > > > REQUIRES a power of 2 frame size.
> > > >
> > > > My current setup is using a 48kHz sample rate and a 128 sample frame
> size
> > > > (~2.5ms).
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.xiph.org/pipermail/opus/attachments/20100519/0f15e757/attachment-0002.htm