“t” is the representation in continuous-time but in discrete time it can
be
represented in the form of sample-count (samp-rate must be known).
nitems_writtenhttp://gnuradio.org/doc/doxygen/classgr_1_1block.html#a742128a481fcb9e43a3e0cd535a57f9e
hold the number of items produced by the block on the output port. This
count along-with “noutput_items” (items that can be produced during
current
work function call), can possibly be used to determine the factor “t”
-Adeel