[speex-dev] DTX in speech

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Wed Dec 10 13:55:57 PST 2003

> I am trying to use the DTX feature of speex to tell if the user is
> speaking. I have VBR, DTX and VAD turned on, but the function
> speex_encode always returns a non-zero value. It is my understanding
> that it should return a zero value when the encoder detects silence?
> Could anyone give me any clues to help figure out why this isn't working
> for me? I am using the 1.13 version of speex on x86 (windows) platform.

Off the top of my head here are a couple things to check:
1) Try with 1.0.3 and see if it makes a difference (1.1.3 is
2) Try feeding it silence (pure zeros) and see if DTX triggers
3) You may want to use the 1.1.x preprocessor which has a better (but
separate) VAD


Jean-Marc Valin, M.Sc.A., ing. jr.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada

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