Speex dev - May 2009 - speex resampler

I'm trying to understand a bit more about the inner workings of the speex
resampler.
I want to do resampling on a voip stream. High quality and low latency is
important.
1) What does speex_resampler_magic() do?
2) I find that resampling has quite an impact on performance and I'm trying
to figure out where the cpu cycles are going and see what can be done to
reduce the cost. I ran a profile a while ago. From what I remember there
appeared to be dynamic memory allocation going on. Any comments on that?
Sorry that I can't be more specific, I need to run the profile again to get
the details.
-- 
Greger
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Greger Burman a ?crit :
> I'm trying to understand a bit more about the inner workings of the
> speex resampler. 
> I want to do resampling on a voip stream. High quality and low latency
> is important.
> 1) What does speex_resampler_magic() do?
The "magic samples" deal with the case where you change the filter
length on the fly. It's really messy logic (that I can't understand
anymore unless I spend a few hours reading the code again) that nobody
should ever have to look at.
> 2) I find that resampling has quite an impact on performance and I'm
> trying to figure out where the cpu cycles are going and see what can be
> done to reduce the cost. I ran a profile a while ago. From what I
> remember there appeared to be dynamic memory allocation going on. Any
> comments on that? Sorry that I can't be more specific, I need to run
the
> profile again to get the details.
There's no dynamic allocation as long as you don't change parameters on
the fly. Otherwise, there's a few source code tweaks you could do that
can lower complexity at the expense of increased memory use.

	Jean-Marc