[Speex-dev] AEC params

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Mon Dec 12 03:37:24 PST 2005

Le lundi 12 décembre 2005 à 02:57 -0800, Suchibrata Kar a écrit :
> Hi:
> Can anyone give some insight on:
> 1) As per the Speex manual, there is a mention of the
> relationship between input frame and echo frame (Pg
> 19, Para 2). I was wondering of what would be the
> ideal delay between these two frames, so that the echo
> is already fed to the canceller and the echo
> cancellation filter is not inefficient.

Smallest as possible as long as your 100% sure that it's positive. In
practice, half a frame is good.

> 2) Corresponding to the above mentioned delay, what
> filter length should we define while creating the echo
> canceller state so that we can expect the AEC to
> remove or reduce the echo.

So far, my rule of thumb is to use about half of the 60 dB reverberation
time. For example, in a small room, the reverberation time is in the
order of 250 ms, so a tail length of 125 ms would be good.


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