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From: dya@unccvax.UUCP (York David Anthony @ W06BF-TV, Concord, NC)
Newsgroups: sci.electronics,rec.video
Subject: Re: VCR comercial eliminator
Message-ID: <1086@unccvax.UUCP>
Date: 1 Sep 88 19:07:47 GMT
References: <257@ivucsb.UUCP> <16314@apple.Apple.COM> <17659@glacier.STANFORD.EDU> <45@calmasd.GE.COM>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 57

In article <45@calmasd.GE.COM>, jnp@calmasd.GE.COM (John Pantone) writes:
> >I don't know why everyone is discussing fade to black detection, special
> >signals in the vertical sync, or whatever for commercial detection.  All
> >ya gotta do is monitor the sound track and wait for the volume to go up.

> Because the "fact" that TV commercials are louder than the program
> material is simply a myth.  The FCC was involved in an investigation
> (but goes on to say that compression is used)

	Loudness is a subjective pheonomenon, and one which probably
causes me more grief (as an AM and TV station consulting engineer)
than any other single subject.

	The FCC investigation into commercial loudness is malarkey.
(However, some situation comedies run heavy levels of compression
as well).  What they did say, is, is that stations were not running
wider peak deviations during commercials than during programs.
Loudness has very little to do with what is seen on the modulation
monitor.  A study measuring the RMS (preferably, in combination
with a real time analyser) of programs and commercials' audio would
most assuredly find that commercials are "louder" in many cases.

	Virtually everyone can get their hands on various devices
(such as the Aphex aural exciter, or any of a number of compressors)
and make 25 kc deviated FM sound louder than hell.  

> There is no signal present on broadcast tv which presages a commercial
> - if there was that network would find itself bankrupt awfully fast -
> can you imagine spending hundreds of millions of dollars advertising
> on a tv station whose viewers could effectively ignore your
> commercials?

	What lawsuits? And consumers already effectively ignore 
commercials.  In my house, the Sony remote control mutes the sound,
substitutes WRFX-FM into the audio, and either an NTSC test pattern
or a live shot of the 4+ acres in the backyard from the three-tube
plumbicon camera dedicated to that purpose. (Don't howl, netters,
it was dropped and registration problems have rendered it worthless
for everything but survellance.

	Besides, at least one network (NBC) inserts a white flag
into the last 3.5 us of lines 21-31 (?)...in the upper right hand
corner. This flashes a number of times approximately 30 seconds
before station break, and comes on at 5 seconds before station break.
Then, the problem is knowing when to rejoin the network. The other
networks have suitable in-band signalling arrangements (I think
ABC has one which can activate a local station ID overlay auto-
matically for those so equipped). The NBC white flag also seems
to preannounce network avails, too.  I've never worked at an NBC
affiliate, (and only do RF, besides) and am not familiar with
the operational aspects.

	Of course, all but the most stupid TV stations are going
to scrub out any in-band signalling, VIR/VITS, whatever...

York David Anthony
DataSpan, Inc