Test app that implements AndEngine and prints frequency (in Hz) of any sound picked up.
This code is very messy and isn't meant to be used in production or anything. It's just a test.
It uses code from various places on the web including:
This 'HelloJni' project for testing the Android NDK https://android.googlesource.com/platform/development/+/master/ndk/samples/hello-jni
This open source guitar tuner: https://code.google.com/p/androidtuner/