I am looking for a method to use either an analog or digital sound input, either live (currently recording), or recorded (ogg, or mp3 format digital), and detect/read the incomming frequencies. I want to be able to get the frequencies at selected time intervals. Does anyone know of an API, or even another method to do this? In case I am unclear, here is an example. Say I have a .ogg file steaming into my program. The incomming musical notes consist of 4 whole notes, A C A C (I believe A has a frequency of something like 430 mhz, but thats not important right now). I want to be able to sample the incomming notes and determin that the frequency of the first note is 430 (or close to it anyhow). How can I do this? NOTE: I am a c++ programmer.

This gets asked here quite frequently:

http://www.gamedev.net/community/forums/topic.asp?topic_id=219101

Contact that person and see if they have any sueful information to pass on

((psst. The A note to which you refer is 440Hz. There is no frequency that we can hear measured in mHz. Corresponding A notes would be: 220, 110, 55, 880, 1760 etc... Just thought I''d say that))