[Speex-dev] Echo cancellation questions

[A B]

Hi!

I have a few questions considering echo cancellation algorithm in Speex:

1. In the manual it's stated that the delay between the input signal and the echo signal must be small. How small should it be? Is for example 100 ms acceptable?

2. Does echo cancellation algorithm deal well with situation, when one of the users of Speex-based VOIP application has "record-what-you-here" sound card mixer option selected? Did anybody test the algorithm in such conditions? In an application I'm working on the result is not nice - both users (especcialy the one with mentioned option enabled) hear periodic (approx. once a second) loud  noise ("knocks"), which seems to be an effect of amplification of background noise caused by echo. Am I using speex_echo_cancel improperly or it's not possible to eliminate echo in such conditions?

3. Does e.c. algorithm works as good in wideband as in narrowband mode?

I'm using Speex 1.1.10 library.

-- 
Greets,
Mikolaj

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