# ServeLots Webinar Pi ## Problem Statement Multiple people in the same room having their own instances of a webinar software introduces a lot of echo. Each individual have to be alert and conscious to mute/unmute as and when they start/stop speaking. ## Possible Solutions A common computer/pi connected to a loudspeaker. Mic can be used in a couple of ways 1. A common table mic. Everyone speak into it. https://www.amazon.in/Cancelling-Microphone-Professional-Computer-Notebook/dp/B088XXVHKN/ Ordered it. 2. Let there be two or more mics. The computer should combine these mutliple mics as one mic. 3. Let each person connect mic to their own computer. However this mic will be shared via WiFi. Then the webinar computer/pi will combine all these remote mics into one. ## Technical Implementation ### Solution 2 - Combine multiple mics ([reference](http://www.pclinuxos.com/forum/index.php/topic,119695.msg905379.html#msg905379)) Doing this, will implement solution 2 and a necessary step in solution 3 1. PulseAudio and PulseAudio Volume Control needs to be installed ``` sudo apt install pulseaudio pavucontrol ``` 2. Set up the mixed sound sink ``` pactl load-module module-null-sink sink_name=MySink ``` 3. Set up the first loopback sink ``` pactl load-module module-loopback sink=MySink ``` 4. Set up the second, third, fourth, etc loopback sink by repeating the step 3 ``` pactl load-module module-loopback sink=MySink ``` 5. To setup the mics for the corresponding loopback sinks, execute the following tasks using the screenshot below 1. Open PulseAudio Volume Control GUI(```pavucontrol```) 2. GoTo **Recording** Tab 3. In the bottom of this tab, for **Show** select **All Streams** 4. The loopbacks will now be visible. Select the corresponding mic for each loopback ![pavucontrol-multipleMICs](https://i.imgur.com/ljN1jbH.png) 6. In the conference/webinar software, select **Monitor of Null Output** as the mic ### Solution 3 - Share mics over WiFi and then combine them 1. To share