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<p class=MsoNormal><span lang=EN-US>Hi<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>We are working on a speaker phone system
using PJSIP and Speex Speech processing API on an ARM platform. Currently we
have spent about a month on getting the AEC to work properly and we have worked
through the most common causes of problems (such as clock drift,
synchronization problems and non-linearity’s in echo path). <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Now we achieve ERLE of about 17 dB which
tells me that the AEC is doing something however we are subjectively not
satisfied. Some references of ERLE taken from this mailing list tells
that 15 dB [1,2] is not good enough and that 30 dB would be fine [3].<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>My question is if 17 dB is in line with
what is expected from the Speex algorithm? <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>You can find some dumped files on this
link: </span><span style='color:#1F497D'><a
href="https://extranet.svep.se/AEC_dump_100ms.zip"><span lang=EN-US>https://extranet.svep.se/AEC_dump_100ms.zip</span></a></span><span
lang=EN-US><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>These files are dumped in mdf.c when running
on the ARM platform with an IP-phone conversation active (only far end
talking). All preprocessors have been disabled. We have been using a high
quality measurement microphone and a fairly high quality PC speaker in the test
setup. The result is similar when we run the signals offline through
testecho.c.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>We have been using PJSIP revision 2709 from
svn which contains Speex-1.2beta3. <o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Best Regards<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>/Johan Nilsson<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Some links:<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>[1] <a
href="http://lists.xiph.org/pipermail/speex-dev/2007-March/005390.html">http://lists.xiph.org/pipermail/speex-dev/2007-March/005390.html</a><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>[2] <a
href="http://lists.xiph.org/pipermail/speex-dev/2005-June/003352.html">http://lists.xiph.org/pipermail/speex-dev/2005-June/003352.html</a><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>[3] <a
href="http://lists.xiph.org/pipermail/speex-dev/2005-June/003358.html">http://lists.xiph.org/pipermail/speex-dev/2005-June/003358.html</a><o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
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