[Speex-dev] AEC: Tips on signal synchronization.

[Marco Pierleoni]

Thanks Jean-Mark for the answers.

I thought about that and I delayed the mic by 50 samples.
In this way I get a few update_foreground = 1, but there are not audible
differences.
Plotting the st->e array, you can see that it is almost null everywhere or
with very low values.

What it seems weird to me is that if you listen the files they are very
similar, so, I think, there should be a way to cancel the echo.

Marco


2009/12/30 Jean-Marc Valin <jean-marc.valin at usherbrooke.ca>

> Maybe you shifted the signal too much. If the mic signal is just one
> single sample *ahead* of the playback signal, then there's no
> cancellation possible (because the system is not causal). Be careful
> with that. Otherwise, if could simply be dropped frames.
>
>        Jean-Marc
>
> On 2009-12-30 07:06, Marco Pierleoni wrote:
> > The problem is that now I have two files very similar (one for mic, the
> > other for speaker).
> > If I play them together I can hardly say that they are two different
> > file for most of the file length.
> >
> > When I try to cancel the echo, I obtain as output almost the same input.
> > The update_foreground variable is always 0. I don't get the conditions
> > which must be fulfilled in order to have update_foreground=1.
> > I see that there is some energy comparison, but I don't get the physical
> > meaning of all the components.
> > Is it normal to get always 0?
> > If the track are into alignment, are there other tracks' properties to
> > consider in order to get a good echo cancellation? Maybe the audio
> > quality? or the relative volume?
> >
> > Thanks for any help.
> >
> > Marco Pierleoni.
> >
> >
> >
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