Hi Kapil, As you mentioned that headset was in use (instead of phone loudspeaker), acoustic echo normally wouldn't occur, so the possibilities of echo source could be: - loop back in audio mixer (by OS or hardware), i.e: output (speaker) signals looped back to input line (mic) in the same device, on win PC this can be configured using the built-in audio setting UI, but I haven't seen such UI on win mobile platform (or may it be configured programmatically and done by other software perhaps)? - distance between devices was relatively close enough, so the talker voice accidentally also got in to other devices mic. BR, nanang On Thu, Aug 12, 2010 at 1:28 PM, Kapil Pendse <kapil.pendse at gmail.com> wrote: > Forgot to mention, I am using the GSM codec. > > On Thu, Aug 12, 2010 at 11:56 AM, Kapil Pendse <kapil.pendse at gmail.com> > wrote: >> >> Hello everyone, >> I'm using pjsip-1.5.5. Compiled one copy for Windows Mobile running on >> Sony Xperia X1 phones. Compiled another copy for Windows XP laptop. >> I've modified the 'pjsua' apps slightly such that there are 4 phones that >> call in to this one laptop. The laptop, joins them all in a conference. All >> of this over WiFi. >> Audio goes through well and all phones are able to communicate with each >> other. But there is this echo on each phone. Whatever is spoken in phone-1 >> is echoed back to phone-1 after about 1~2 seconds (after it is heard on the >> other phones). >> The laptop's mic and speakers are muted, and port 0 of laptop is NOT >> connected to the rest of the conference. >> All phones are equipped with headset, so that the backpanel 'speakerphone' >> is NOT being used. >> Conference bridge connections: >> phone-1 - port 3 = transmitting to ports 4,5,6 >> phone-2 - port 4?= transmitting to ports 3,5,6 >> phone-3 - port 5?= transmitting to ports 3,4,6 >> phone-4 - port 6?= transmitting to ports 3,4,5 >> I tried to use the Echo cancellation algorithm (ec-tail=default 256). Also >> tried smaller values of ec-tail. But the moment I use anything other than >> ec-tail=0, the phone's just can't handle it. The app bogs down the CPU and >> audio becomes horrible. The app's UI stops responding. So I'm guessing the >> algorithm is too heavy for the cellphone CPU. I saw in a post that there was >> a lighter "echo suppression" algorithm available, but didn't figure out >> where in the code it was. Is that the default anyway? >> What could be done to get around this echo problem? Any help and >> suggestions would be appreciated. >> Thanks and best regards, >> Kapil >> -- >> "The Power to Imagine, is The Power to Create!" >> -TTux > > > > -- > "The Power to Imagine, is The Power to Create!" > -TTux > > _______________________________________________ > Visit our blog: http://blog.pjsip.org > > pjsip mailing list > pjsip at lists.pjsip.org > http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org > >
