How to ignore the first and the last 10% of the videoCaption ?

edit

just use for :

int partBegin = 0.1*length;
captRefrnc.set(CV_CAP_PROP_POS_FRAMES,partBegin );
for (int i=partBegin;i<static_cast<int>(length*0.9);i++)
{
    captRefrnc >> frameReference;
    if (frameReference.empty()){
        cout << " <<< AD sequence ended!  >>> " <<endl;
        break;
    }
}

maybe like this

Mat frameReference;
double lengthAD = captRefrnc.get(CV_CAP_PROP_FRAME_COUNT);
int partBegin = 0.1*length;
captRefrnc.set(CV_CAP_PROP_POS_FRAMES,partBegin );
while(1){
    captRefrnc >> frameReference;
    partBegin++;

    if (partBegin > 0.9*length){
         break;
    }
    if (frameReference.empty()){
        cout << " <<< AD sequence ended!  >>> " << sourceReference <<endl;
        break;
    }