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To have this testing application on your own OpenMeetings instance you need to download and copy the file: http://svn.apache.org/repos/asf/incubator/openmeetings/trunk/singlewebapp/WebContent/src/test/test-setup.lzx.swf11.swf
To your local: $RED5_HOME/webapps/openmeetings/
You can then access it with: http://localhost:5080/openmeetings/test-setup.lzx.swf11.swf
(localhost of course needs to be replaced if you run your red5 server in the network).
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To re-broadcast with different settings best method is to press F5 and restart the application!
AEC Features are enabled by default the checkbox to enable them is at the bottom of the Mic settings: