title: VoIP, SIP, noice reduction, echo cancelation
body: <p>I am tweaking an existing SIP solution for asterisk VoIP. It is working, but it has no sound quality control or no filters to improve the sound on bad lines. I searched google over and over for existing Delphi solutions in this area or some algorithms, but it seems Delphi is very poor here. I know there are commercial libraries out there that offer at least some of this. But I am looking for free source code so I can either use it or do my own implementation of it. </p>
  
  <p>I have already implemented jitter info and jitter buffer. What I am now looking is:</p>
  
  <ol>
  <li>Filters: Noise reduction, Echo cancelation...etc</li>
  <li>Any other means to improve sound when lagging occurs and in general the line quality is bad.</li>
  </ol>
  
  <p>Do any of you have the knowledge where to get any of this? If nothing else you can provide algorithms or other languages code.</p>
  
  <p>P.S</p>
  
  <p>Any solutions I make will be released back to the community. I will release jitter buffer shortly.</p>