is there any recommendation for a library (c++, Win32, open source) to get the sound from a microphone?
Thanks
Try having a look at OpenAL[1] it might be overkill, but should be able to record from microphone as you wanted. There exists some pretty good articles about it on Gamedev.net[2] although I'm afraid none of them tells you how to record from a microphone. You should however be able to find the answer for that in the documentation. :) good luck,
[1] http://connect.creativelabs.com/openal/default.aspx
[2] http://www.gamedev.net/reference/articles/article2008.asp