For what it&#39;s worth, I&#39;ve had significantly better luck with the WebRtc VAD. It&#39;s pretty good.<div><br></div><div><a href="http://code.google.com/p/webrtc/source/browse/#svn%2Ftrunk%2Fsrc%2Fcommon_audio%2Fvad%2Fmain%2Fsource">http://code.google.com/p/webrtc/source/browse/#svn%2Ftrunk%2Fsrc%2Fcommon_audio%2Fvad%2Fmain%2Fsource</a><br clear="all">
<br>In general, the WebRTC voice engine seems to be more sophisticated and mature than the Speex preprocessor (as opposed to the Speex codec, which is pretty good).<br><br>Ken Smith<br>Cell: 425-443-2359<br>Email: <a href="mailto:ken@alanta.com" target="_blank">ken@alanta.com</a><br>
Blog: <a href="http://blog.wouldbetheologian.com/" target="_blank">http://blog.wouldbetheologian.com/</a><br>
<br><br><div class="gmail_quote">On Mon, Aug 29, 2011 at 1:36 PM, Yanick Bourbeau <span dir="ltr">&lt;<a href="mailto:ybourbeau@mrgtech.ca">ybourbeau@mrgtech.ca</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">

  
    
  
  <div bgcolor="#FFFFFF" text="#000000">
    From 1.2rc1 source code:<br>
    
    <span style="color:rgb(136, 0, 0);font-family:monospace;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:16px;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:pre-wrap;word-spacing:0px;background-color:rgb(255, 255, 255);font-size:medium"><br>

      <big><font color="#000000">preprocess.c:<br>
          <br>
          /* FIXME: This VAD is a kludge */<br>
          st-&gt;speech_prob = Pframe;<br>
          if (st-&gt;vad_enabled)<br>
          {<br>
          if (st-&gt;speech_prob &gt; st-&gt;speech_prob_start ||
          (st-&gt;was_speech &amp;&amp; st-&gt;speech_prob &gt;
          st-&gt;speech_prob_continue))<br>
          {<br>
          st-&gt;was_speech=1;<br>
          return 1;<br>
          } else<br>
          {<br>
          st-&gt;was_speech=0;<br>
          return 0;<br>
          }<br>
          } else {<br>
          return 1;<br>
          }<br>
          <br>
          AND<br>
          <br>
          case SPEEX_PREPROCESS_SET_VAD:<br>
          speex_warning(&quot;The VAD has been replaced by a hack pending a
          complete rewrite&quot;);<br>
          st-&gt;vad_enabled = (*(spx_int32_t*)ptr);<br>
          break;<br>
          <br>
          <br>
          As you can see, it is a hack, not supposed to be very good.
          Still, weird that you get<br>
          this result. If you want a sample to test it, check speexenc.c
          file in speex source code package.<br>
          I usually implement this kind of feature outside of speex
          becauses I want a better control<br>
          on how it happens and when to do something about it :)<br><font color="#888888">
          <br>
          Yanick Bourbeau<br>
        </font></font></big><br>
      <br>
      <br>
      <br>
      <br>
    </span><div><div></div><div class="h5">On 11-08-29 04:16 PM, Clifton Craig wrote:
    <blockquote type="cite">+1 on this question as I
      wanted to start playing with it as well.
      <div><br>
        <div>
          <div>On Aug 29, 2011, at 9:41 AM, Shridhar, Vasant wrote:</div>
          <br>
          <blockquote type="cite"><span style="border-collapse:separate;font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium">
              <div link="blue" vlink="purple" lang="EN-US">
                <div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif">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.<u></u><u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif"><u></u> <u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif">Does
                    anyone have any information on how to use this or
                    some example code to set this up I might try.<u></u><u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif"><u></u> <u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif">Thanks,<u></u><u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif"><u></u> <u></u></div>
                  <div style="margin-top:0in;margin-right:0in;margin-bottom:0.0001pt;margin-left:0in;font-size:11pt;font-family:Calibri, sans-serif">Vas<u></u><u></u></div>
                </div>
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              </div>
            </span></blockquote>
        </div>
        <br>
      </div>
      <br>
      <fieldset></fieldset>
      <br>
      <pre>_______________________________________________
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</pre>
    </blockquote>
    <br>
  </div></div></div>

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<br></blockquote></div><br></div>