Commercial killers

[Steve Simmons]

Adam Shostack <adam at bwh.harvard.edu> writes:

>	Yes, but the tv stations put in a short period of black &
>silence before returning to the show.  I'm pretty confident that this
>is what the 'zip through commercials' vcrs cue on.

Darned close.  The article I saw said it detects the period of black
and silence and puts a `notch' on the tape at each such switch.  The
notch can be detected at fast-forward speeds.  My question is - what
happens if there is black/silence *between commercials*?  How does
the VCR know that what follows a mark is show or merely the next
commercial?
-- 
Simmons' Law Of Alcoholic Expectations:
  The best stuff always happens after the meeting, when everyone goes to
  the bar.
Correlary: Any meeting which doesn't adjourn to the bar isn't worth going to.