Knowing acceleration, gyro and compass data how to calculate north direction

I have a small video camera with an attached sensor. I can get from the sensor his acceleration, gyro and compass data. Knowing this data I need to rotate the camera so that it will look strictly north.

I know how to rotate the camera, but how to calculate the right angle?

How can I do it? Or where can I read about it? Or, if this is not a right place to ask such a question, what is the right place?

EDIT:

All coordinates are in an Earth-fixed inertial frame.The compass and accelerometer readings are unit vectors, and the gyroscope readings are in radians per second