Speex dev - Apr 2006 - Echo cancellation performance and metalic noise

Hi,

I use speex1.1.10 [June 10, 2005]in my VoIP
application and it works very good for me. But
sometimes I get loud metalic noise. Turning off EC,
disappears the noise right away. I use EC with
denoiser ON, AGC OFF, echo tail 400 ms. Has anyone
experienced this?

Since Speex1.1.11 has improvement for EC, I tried with
the latest release [Speex1.1.12, which has fixed point
EC]. But in my test, EC performance of 1.1.12 is worse
than Speex1.1.10. I can always hear some suppressed
echo in current[1.1.12] build but with older[1.1.10]
it is much better, almost no echo in most cases. I
replaced corresponding *float* with *spx_int32_t* to
use fixed point, in my code, to use the changed speex
function speex_echo_cancel();

Could that be a reason of fixed point code in Windows
platform?

Please advise.

Thanks 

-Shantanu





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> I use speex1.1.10 [June 10, 2005]in my VoIP
> application and it works very good for me. But
> sometimes I get loud metalic noise. Turning off EC,
> disappears the noise right away. I use EC with
> denoiser ON, AGC OFF, echo tail 400 ms. Has anyone
> experienced this?
What happens if you turn off the denoiser?
> Since Speex1.1.11 has improvement for EC, 
Actually, 1.1.11 had a strange instability problem, so I don't recommend
it.
> I tried with
> the latest release [Speex1.1.12, which has fixed point
> EC]. But in my test, EC performance of 1.1.12 is worse
> than Speex1.1.10. 
Could be a regression, or just the tuning that's no longer optimal for
your exact conditions.
> I can always hear some suppressed
> echo in current[1.1.12] build but with older[1.1.10]
> it is much better, almost no echo in most cases. 
Do you have any example files (that run with testecho). It's impossible
to say anything otherwise.
> I
> replaced corresponding *float* with *spx_int32_t* to
> use fixed point, in my code, to use the changed speex
> function speex_echo_cancel();
> 
> Could that be a reason of fixed point code in Windows
> platform?
Could what be the reason for what? BTW, if you use a PC, you don't need
fixed-point.

	Jean-Marc