[Speex-dev] mdf no sound issue

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Fri Nov 18 18:05:41 PST 2005

Hi Tom,

> Ok so I tested with the new code, same result- frame size=
> 160, filter length=160 ms/1280 samples, 8000 Hz

I usually recommend a bit shorter than that, but I don't think the
problem is really there.

> diverged after 9564 calls/packets or 191 seconds.  My system
> stays relatively in synch but is not perfect- difficult to measure
> if there is any clock drift, but it probably is.

What does it mean "relatively in sync". Either capture and playback use
the same clock or they don't. If they don't, see previous email thread
about AEC with different clocks.

> In order to make it break faster I use an open air usb microphone
> that is part of a logitech notebook camera, and then plug headphones
> into the speaker jack (sensitive mic can pick this up).

Do you mean the camera also has a headphone jack or you're using a
different device for playback and capture. Also, do you have some
acoustic feedback on top of that (i.e. are the speakers playing the
microphone signal), in which case, the whole thing is unstable to begin
with and the AEC might not be fast enough to stabilize it.


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