Input vs output items query

Hi

I have a block that takes n number of input samples and has to return n

  • 5 samples. (something analogous to a cyclic prefix insertion. where
    the number of samples coming out will be more than the number going in)
    Since the relation between number of input and output samples may or may
    not be an integer, i am unsure as to which type of block to use.

If I use the “general” type, do I have to make changes in the forecast()
method to allow for this? If, yes, what do I need to change?

Because as of now, my input and output array sizes are the same and
obviously that throws up an error.

I’m a new gnuradio user and i’m still not at grips with this whole
concept of number of input and output samples.

Thanks in advance
AKY