[Speex-dev] Time Delay Estimation

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Thu Jun 7 16:54:49 PDT 2007

> Does the echo canceller maintain some data structure that I might be
> able to use if I wanted to estimate the amount of delay between the
> near-end and far-end signals? I'd like to be able to do this in order to
> optimally align the signals before passing them to the canceller. There
> seem to be many milliseconds of latency in a Wintel audio subsystem and
> I would like to accurately compensate for that rather than just using a
> huge echo tail.
> I would guess that the adaptive filter must compute some good data that
> I could use as observations for a tracking algorithm.

If you don't need too much accuracy, you can look at the prop[] array.
The index of the largest element in "prop" will give you the delay in
frames. If you need more accurate, then you'll need to convert the
frequency-domain weights (W) tp time domain and look for the max.


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