private int CalculateTimebase(double framesPerSecond)
{
// based on https://developer.apple.com/library/mac/#documentation/AppleApplications/Reference/FinalCutPro_XML/FrameRate/FrameRate.html#//apple_ref/doc/uid/TP30001158-TPXREF103
return (int)Math.Round(framesPerSecond, 0);
}