Speex dev - Jul 2010 - Sound card problem in acoustic echo

Thank you.

But it will cost you a long time to get the accurate play and capture
frequencies.
Does your program test two frequencies of the sound card each time? Because
different sound cards have different frequency errors.
And the resampling program is also time consuming because the target frequency
is
so close to the sampling frequency of the input signal, isn't it?

I have tested program based on Windows waveform functions and also DirectSound.
They have similar frequency error.

BTW: What's your conclusion of ASIO driver? Why "it was of no practical
use"?
> I worked some time for a company doing AEC using Speex on Windows.It is
true it depends a lot on sound card models. I remember I could do AEC by
resampling frequencies so play and record frequencies where equal.Frequencies
where aprox 100Hz appart.Also, I know that on other cases AEC was achieved by
disabling FX DirectSound effects where it wasn`t possible before that.Try to
disable all you don't need before calling Speex AEC function.
> Also, I tried the ASIO driver,as an experiment. I think it worked, but it
was of no practical use.
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I remember?I had to expose the echo cancelation level implementing a
get_echo_level( ) function based on this:
http://lists.xiph.org/pipermail/speex-dev/2008-September/006889.html
?
Using that value and averaging samples?as?"fedback" I did small
corrections to sampling rate until convergence, although this not always
worked.When it did, convergence was quite fast (seconds).
Resampling did not introduce noticiable CPU increase.But may be the small time
used for conversions was the cause of non-convergence.I think this?path is hard
and uncertain, and?now,i would dive first in DirectSound to try to obtain
synchronized streams before passing them to speex.
?
Regarding ASIO, you have to install a special "driver"? for it to
work,and?this seems unaceptable for general users.

--- El jue, 22/7/10, limaoquan2000 <limaoquan2000 at 126.com> escribi?:


De: limaoquan2000 <limaoquan2000 at 126.com>
Asunto: [Speex-dev] Sound card problem in acoustic echo
Para: speex-dev at xiph.org
Fecha: jueves, 22 de julio, 2010 12:25


Thank you.

But it will cost you a long time to get the accurate play and capture
frequencies.
Does your program test two frequencies of the sound card each time? Because
different sound cards have different frequency errors.
And the resampling program is also time consuming because the target frequency
is
so close to the sampling frequency of the input signal, isn't it?

I have tested program based on Windows waveform functions and also DirectSound.
They have similar frequency error.

BTW: What's your conclusion of ASIO driver? Why "it was of no practical
use"?
> I worked some time for a company doing AEC using Speex on Windows.It is
true it depends a lot on sound card models. I remember I could do AEC by
resampling frequencies so play and record frequencies where equal.Frequencies
where aprox 100Hz appart.Also, I know that on other cases AEC was achieved by
disabling FX DirectSound effects where it wasn`t possible before that.Try to
disable all you don't need before calling Speex AEC function.
> Also, I tried the ASIO driver,as an experiment. I think it worked, but it
was of no practical use.




??????????????? 
-----Adjunto en l?nea a continuaci?n-----


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