Mic/Speakers Audio Feedback in VLC API

Question

I'm building a Webcam recording application with Qt 5.3 using vlc-qt, the problem is while previewing Audio/Video high feedback/noise and echo starts and gets higher, I've been googling and found it's the effect called Larsen's effect and how it's happening.

Notes:

• I know using a headphone is a solution
• I'm on a Windows 7 Ultimate Notebook
• The Microphone Boost on zero dB is less noise but echo is persistent

My Questions:

• How other webcam recording applications suppress the noise and the echo?
• Specifically, how it can be fixed in VLC, your answer can be commandline arguments, notes or instructions to do in VLC software, it doesn't have to be code

Thanks!

Answer 1

I found http://www.dspcottage.com/en/algorithms/AEC a C++/MFC echo cancellation application based on Speex, but I needed to use it in Qt so I scrapped all MFC related code and here is the final solution https://github.com/Marware/Cpp_AEC