Heart rate algorithm and implementation

I need the algorithm and implementation library for building the application that can read the heart rate based on the flash LED. A sample application you can get inspired is the Android application called "Instant heart rate". Here are the requirements: We own the IP and the library without restriction of usage The library must run on android The reading is based on the flash light on the phone Please build the minimum android app that uses the algorithm 10 seconds for the reading through the flash light The algorithm should be as good as or better to the instant heart rate app Built on Android 2.3