[Speex-dev] Speex VAD always returning 1

Yanick Bourbeau ybourbeau at mrgtech.ca
Mon Aug 29 13:36:12 PDT 2011

 From 1.2rc1 source code:


/* FIXME: This VAD is a kludge */
st->speech_prob = Pframe;
if (st->vad_enabled)
if (st->speech_prob > st->speech_prob_start || (st->was_speech && 
st->speech_prob > st->speech_prob_continue))
return 1;
} else
return 0;
} else {
return 1;


speex_warning("The VAD has been replaced by a hack pending a complete 
st->vad_enabled = (*(spx_int32_t*)ptr);

As you can see, it is a hack, not supposed to be very good. Still, weird 
that you get
this result. If you want a sample to test it, check speexenc.c file in 
speex source code package.
I usually implement this kind of feature outside of speex becauses I 
want a better control
on how it happens and when to do something about it :)

Yanick Bourbeau

On 11-08-29 04:16 PM, Clifton Craig wrote:
> +1 on this question as I wanted to start playing with it as well.
> On Aug 29, 2011, at 9:41 AM, Shridhar, Vasant wrote:
>> I have been trying to understand how to get the VAD algorithm 
>> working.  I sent an input stream of all zeros into the preprocessor 
>> but still got a return value of 1 indicating that speech was 
>> detected.  Is this feature not available with the latest release?  I 
>> thought at the very least it would detect this as silence and return 
>> 0 but that does not seem to be the case.
>> Does anyone have any information on how to use this or some example 
>> code to set this up I might try.
>> Thanks,
>> Vas
>> _______________________________________________
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>> Speex-dev at xiph.org <mailto:Speex-dev at xiph.org>
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