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speedvoip
Vetran
Joined: August 07 2008
Location: Canada
Posts: 156
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| Posted: May 05 2009 at 11:22am | IP Logged
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Hi Randal:
With latest media engine, when single line app example runs at some low bandwidth network such as Oman and codec is G.729, callee often hears its own echo sound heavily. It seems that media engine not export API for removing/canceling echo. In most cases, we need a flexible way to control echo.
How to do that?
Thanks,
George
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support
Administrator
Joined: January 26 2005
Location: United States
Posts: 1666
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| Posted: May 05 2009 at 12:26pm | IP Logged
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Hello George,
To make line echo removal simple for VOIP application developers, we need to add native line echo cancellation to the media engine (on each individual phone line). It is not available at the moment but we know we need to add it to the product.
We have a few other customers who are actually performing their own line echo cancellation using the RAW RTP packet access capability of the media engine. However, using this approach is not as easy as simply enabling an internal media engine function. The main reason application level line echo cancellation is a bit hard is because the app must convert from raw RTP media format to PCM before being able to use the RTP samples in a line echo canceller. It is possible to do it (and it works) but it is “clunky”. The only real solution for all of us is for LanScape to implement full line echo cancellation on each phone line via the API. That way VOIP apps could simple enable or disable line echo cancellation as needed. Simple.
Maybe we should plan on including this when the jitter buffer/packet loss concealment updates are available. If I had the proper line buffer echo cancellation routing in my hands today (i.e. a reference design), getting it implemented and functional in the media engine would be straight forward. Feel free to forward ideas, test code, whatever if you wish. This is on our engineering “todo” list.
You >>>
… when single line app example runs at some low bandwidth network such as Oman and codec is G.729…
<<< Support
What is “Oman”?
Item 1 – Audio Recording:
If it is possible, make a call using your media engine code and record the call’s full duplex audio to a wave file. Post the wave file to your support FTP account and I will examine it. I am curious how much echo you are experiencing in your VOIP network.
Randal
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LanScape Support Forum -> LanScape VOIP Media Engine™ - Technical Support
Topic: How to remove echo sound
