[Speex-dev] Is 17 dB ERLE normal?

Johan Nilsson han at svep.se
Wed May 27 06:15:55 PDT 2009


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).

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].

My question is if 17 dB is in line with what is expected from the Speex algorithm?

You can find some dumped files on this link: https://extranet.svep.se/AEC_dump_100ms.zip
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.
We have been using PJSIP revision 2709 from svn which contains Speex-1.2beta3.

Best Regards
/Johan Nilsson

Some links:
[1]   http://lists.xiph.org/pipermail/speex-dev/2007-March/005390.html
[2]   http://lists.xiph.org/pipermail/speex-dev/2005-June/003352.html
[3]   http://lists.xiph.org/pipermail/speex-dev/2005-June/003358.html

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