[Speex-dev] Speex and RTP

[David Hogan]

Hi Jean-Marc,

As promised, I 'got a chance' and had a play with your resampler :)

I've tested the following conversions:

48000 <-> 16000
44100 <-> 16000
48000 <-> 8000
44100 <-> 8000
16000 <-> 8000

One thing I've noticed is that even on the highest quality, I seem to be
getting plenty of high pitch artifacts - perhaps I am using it wrong. My
main test is from 48000Hz -> 8000Hz, for which I previously ran a 4000Hz
lowpass filter over the 48000Hz data, followed by dropping 5/6 samples.

Integrating either a 4000Hz or 8000Hz lowpass filter for each of the
above cases however produces nice results. It's definitely handy to be
able to do 44100Hz conversions now :)

Was it your intention that additional filtering be required when using
the resampler? If not then I've probably botched the usage somehow.

Cheers,
Dave


> and
> when
> I get a chance I'll integrate your resampler into some code of ours
and
> see how it goes. We're currently using a combination of my own
> resampling code (for simple cases) and the Windows ACM Library (which
> yields poor results, no filtering as far as I can tell) so your
> development of this functionality is quite timely for us (thanks :) ).
> 
> Cheers,
> Dave
> 
> 
> > -----Original Message-----
> > From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca]
> > Sent: Monday, 5 February 2007 9:27 PM
> > To: David Hogan
> > Cc: Randy Schefiele; speex-dev at xiph.org
> > Subject: Re: [Speex-dev] Speex and RTP
> >
> > > I believe there is new resampling functionality in the
> > speex svn head,
> > > although I haven't tested it yet. You might also want to check out
> > > 'Secret Rabbit Code' for your resampling.
> >
> > Yes, I've just been working on a resampler recently. Its
> > changing a lot,
> > but it's now usable. I'd actually be quite happy to have some
> feedback
> > on it.
> >
> > 	Jean-Marc
> >
> >
> > > Hope this helps.
> > > Dave