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Echo Created by Double Processing of Line In Audio Signal

Question asked by tlindsey Administrator on Jan 15, 2015
Latest reply on Jan 15, 2015 by tlindsey

The challenge involves a setup with a Room 220 Codec + Phone. On the Room 220 side, the Line Out is connected to a Speaker Bar. The Line In (1) is connected to a local pc for sharing audio signal (where the DVI-I In is connected to the local pc for sharing video signal).


During a Recording via Video Center, I would like to share content (both audio & video) - for example a movie. The Audio Signal from the PC is being picked up by the Codec at the Line In level. At the same time, the Audio Signal is sent as pass-through from Line In to Line Out - to the local Speaker Bar. In other words, I hear the Audio of the movie I am playing via the Local Speakers.


In my recording on LifeSize Video Center, I hear the audio twice - short after each other. It sounds like somekind of echo, but when I think about it, it is the Audio Signal from the PC that is being processed twice by the Codec to include it in the Recorded Movie. The first is the Line In signal that is being sent by the Codec towards Video Center. The second is the pickup of the local Sound by the connected Phone.


In order to solve this, I am looking for a practical solution. One option would probably be to mute the Phone (only the phone, not the Line In) to make sure the Audio Signal is not being processed in the Recorded Movie twice. But this means the user needs to understand this and take the required action accordingly.


With Usability in mind, I am searching for solution where the Codec/Phone is smart enough to detect the two similiar Audio Signals and filters the audio input of the Phone for that specific Audio Signal. You could say it is a form of Acoustic Echo Cancellation, but then on the near side. So at the end, the phone does not send through the signal it picks up from the Local Speakers.


Is this achievable on the current setup? What things should I need to change in the configuration or even physical cabling?