Microphone auto level

Question

Hi all!

I'm looking for solution to tune mic's level in my VoIP app. I can get a level of sound, but want also tune mic's "volume" when it too low or too high in real-time. Like in Skype...

It looks easy ex facte, but I think the algorithm should be a bit smarter then just turning the volume when level comes over hihg/low limits.

I'm using .Net 2.0 on Win platform. Are there any ready libraries for .Net or even on C (so I can port it) or even just description of such methods/algorithms? I've tried to google but with no luck.

Thank you!

Answer 1

The commonly used name for this is AGC (Automatic Gain Control) and it is not quite as easy as it sounds. In a basic AGC scheme you have a fast "attack", which means that you reduce the gain very quickly when the input level increases, and then use a larger time constant to increase the gain more slowly when the input level drops.

Answer 2

Try this for a start: Get and set the wave sound volume

It uses Windows API in C# through P/Invoke.