I took a different approach, assuming the purpose of the 30-sec skip function is to string together several of these to cover an entire commercial break. Since one can never be sure how many 30-sec segments make up a break, I decided to just use the normal FF function, and hit PLAY when the action re-starts (which is usually pretty easy to tell). The problem with this is that, due to reaction time, one inevitably overshoots. To compensate for this, some DVRs include an algorithm to rewind for a short time after PLAY has been pressed following a FF; the duration of the rewind time is a function of how many FFs have been pressed. I just simulated this algorithm in my pcf, and it seems to work reasonably well.