[Speex-dev] Frame size for speex_echo_state_init

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Tue Dec 5 15:03:25 PST 2006

Non-power of two will work and will just be a bit slower. For example,
320 is 64*5, so there's a single radix-5 step involved. Nothing
catastrophic. In general, I recommend 20 ms or smaller, not bigger.


Coffey, Michael a écrit :
> The speex manual says: "It is recommended to use a frame size in the
> order of 20 ms (or equal to the codec frame size) and make sure it is
> easy to perform an FFT of that size (powers of two are better than prime
> sizes)."
> What is the impact of using a non-power-of-two frame size here? Since 20
> ms of 8000 (or 16000) is not a power of 2, I have to make a choice. It
> would be most convenient to pass my regular packet size (320 samples).
> Would there be any advantage for me to re-buffer the samples and pass
> them 256 (or 128) at a time? 
> Thanks, by the way, for the very interesting and useful software!
> -Michael
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