Input Capture period calculations

[Jinzpaul4u]

Hello there,

I'm using the dsPIC33fj256gp710 MCU to obtain the pulse width of a PWM generator using Input Capture module(rising and falling edge of the pulse).
The program works fine, and I can obtain a time period. However, I need to do some further calculations with the period value, and I don't really know how to convert the obtained value into a number that can be used in regular math functions. The time period I normally get is 960ms (I've connected an oscilloscope to the circuit as well to get this value).

mean while I am using timer counter register to check time period.The essential portions of the code are shown below (with comments):

unsigned int timeperiod1=0;
unsigned int timeperiod2=0;

void __attribute__((__interrupt__)) _IC1Interrupt(void)
{
unsigned int t1,t2;

if(PORTDbits.RD8) // rising edge of the pulse
{	timePeriod1=0;
	TMR2=0;// timer counter become reseted 
	t1=IC1BUF; // present time period value
	T2CONbits.TON = 1;// Start Timer
	
	
}
else if(!PORTDbits.RD8)// falling edge of the pulse
{
	T2CONbits.TON = 0;// Stop Timer	
	timeperiod1=TMR2; // time period calculation based on timer
	t2=IC1BUF;       // updated value
	timeperiod2=t2-t1; //  time period calculation based on inputcapture
		
}


}

Here I am getting both timeperiod1 and timeperiod2 are equal. that is=18192

based on timer Period calculation

Fosc=80MHz // using PLL
Fcy =Fosc/4=20MHz // timer frequency 
Tcy =1/Fcy= 50ns // timer period
prescaler=1:1
TMR1 increments (increases by 1) every 1 x Tcy seconds =50ns.

Total time period is =18192 * 50n=0.9096ms

but actual time period in osciloscope is=960ms.

could someone tell me how I could achieve this or what I am doing wrong in the code I have?

This may seem really basic, but I'm quite inexperienced and could really use some help in this situation.