[Speex-dev] Performance of the acoustic echo canceller

[William Zhang]

All, 
 
Wonder why all my posts has no line breaker when it displayed the forum... I used Hotmail(Windows Live Mail) 
with FireFox 2.0.  I am posting this msg with IE 7.0 and see if it make any difference.  Anybody experienced the
same issue and how to workaround it?
 
Thanks a lot! 
 
Regards,
William 


From: espzzh at hotmail.comTo: jean-marc.valin at usherbrooke.caCC: speex-dev at xiph.orgSubject: RE: [Speex-dev] Performance of the acoustic echo cancellerDate: Tue, 6 Mar 2007 01:39:11 -0800



Hi Jean-Marc, Thanks for the suggesting.  I tried the test wtih my recording file offline through the testecho. I got the same result(no prepocessor echo suppression) as my recording file for that live call. Basically I don't see the difference between input_frame and output_frame.   As I mentioned in my original post, the echo return loss is about 20db. I guess the echo cancelleris not really actively cancelling the echo in such condition? But without the echo sppression/NLP, echo is still noticable.  I used the same onboard sound card for the speaker and microphone.  As far as I can tell,  the delay between echo_frame and input_frame is consistent and about 10ms. I would assumethe synchronization is not a problem.  And I also have some other echo recording files which has almost 0db echo return loss and about 20ms consistent delay.  The EC can achieve about 10 to 15db echo return loss enhancement in this case.  Is it normal?  I would think 25+ db ERLE plus 15+ NLP/ES should make the residual echo inaudible. I am not sure about the nonlinearity of those recording files but I would appreciate it if you could take a look  of those.  I uploaded  them to http://www.sharebigfile.com/file/101511/capture-zip.htmlCapture1.zip is first case, 20db ERL.  Capture2.zip is second case, 0db ERL. Bunch of thanks!  Regards,William

> Date: Mon, 5 Mar 2007 20:27:39 +1100> From: jean-marc.valin at usherbrooke.ca> To: espzzh at hotmail.com> CC: speex-dev at xiph.org> Subject: Re: [Speex-dev] Performance of the acoustic echo canceller> > Best advice I can give is to record the near-end and far-end files, pass> them through testecho (disable the preprocessor) and check the result.> Then check why it's not working (if that's the case). Some usual suspects:> > 1) Clock drift between capture and playback> 2) Bad synchronisation> 3) A non-linearity somewhere (bad speakers, noise gate, ...)> > If you try everything and can't find what the problem is, please upload> the files somewhere and send an email with the links (do not email the> files directly).> > Jean-Marc> > William Zhang a écrit :> > Hi All, I am working on my master project to port the Speex Acousic> > Canceller to FPGA. But I am not able to get a satisfied result in its> > performance whenI integrated it to a SIP softphone as my first step.> > The SIP softphone calls to a PSTN gateway and lands to my land line> > phone. I can hear the echo of my every word while I talks on the> > land line phone. I am using G.711 codec, frame_size 80 and both> > 1024 and 2048 tail length. The code was compiled as floating point> > and fixed point in the PC. But noneof them help. I made sure the the> > synchronization between echo_frame and input_frame was stable and the> > delay is consistant about 10ms. The echo return lossis around 20db> > but output_frame and input_frame signal is about the same. I even> > tried Jean-Marc's latest mdf.c from the subversion but no luck. Has> > anyone test the performance in any other softphones and how well does> > it work? I have the recording files, anyone would be interesting in> > taking a look? I wonder if there is something wrong with my input,> > setup...BTW: did anyone ever try to port the algorithm to hardware?> > I will do some profiling and implement the most compuation expensive> > function in the Xilinx FPGA.I would really appecriate if anyone can> > share some experience or provide adavise and suggest! I like to> > contribute my work to the Speex project if my project turns out to be> > good end. Regards,William > > _________________________________________________________________ > > Connect to the next generation of MSN Messenger > > http://imagine-msn.com/messenger/launch80/default.aspx?locale=en-us&source=wlmailtagline> > > > > > > > ------------------------------------------------------------------------> > > > > > _______________________________________________ Speex-dev mailing> > list Speex-dev at xiph.org > > http://lists.xiph.org/mailman/listinfo/speex-dev

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