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From: "John S. Dyson"
Subject: Re: Detection of television commercials
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Fri, 6 Dec 2002 12:25:30 -0500
NNTP-Posting-Date: Fri, 06 Dec 2002 12:17:44 EST
wrote in message news:firstname.lastname@example.org...
> Kevin Aylward wrote:
> > John Jardine wrote:
> >> Richard Haendel wrote in message
> >> news:GZXH9.45680$hK4.email@example.com...
> >>> Can anyone provide information on how to do this? I'm not looking to
> >>> build a "commercial killer" but I need to record and log certain
> >>> ones for a client.
> >>> Thanks,
> >>> Richard
> >> Have occasionally thought of picking up ad's by monitoring their
> >> greater loudness wrt normal programming.
> >> The perceived loudness increase appears to be from being
> >> 'compressed' up to the hilt and should be distinguishable by a very
> >> flat audio spectrum.
> > Not in the UK. No question about it, they simple turn the volume way up
> > on adverts.
> They can't.
> TV audio is broadcast at a certain level.
> Attempt to turn it up beyond that level and limiters in the transmitter will
> kick in.
Actually, it is possible to make the audio more dense for commercials, without
overmod or causing the limiters to 'kick-in.' There are some tricks that go
far beyond simple AGC that can make audio more dense, and have the gainriding
work very quickly -- but not really increase distortion in commercial-type material.
Audio can stand some 'clipping' or hard dynamic limiting without sounding very
distorted also. A combo of an aggressive dynamics processor and some
carefully crafted peak limiting can create louder sound than people would
normally associate with properly modulated signals.
So, the TV station could indeed push more volume into the dynamics processor,
and up to a reasonable limit, the sound would continue to get louder, even though
the peak deviation wouldn't increase much. This can only be pushed so far.
In fact, it isn't that abnormal to push the signal levels high enough that the
processors will purposefully clip the high frequencies (when used with bandpass, the
intermod isn't horribly obnoxious.) This is one reason for the 'mushy' FM
sound on 'loud' FM stations. The same concepts apply to TV audio.
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