NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/crypt/6447

Internet Message Format | 1993-01-06 | 2.7 KB

Path: sparky!uunet!dtix!oasys!kcwc.com
From: [e-mail] (Curt Welch)
Newsgroups: sci.crypt
Subject: Re: Any way to *CREATE* Vcr+ (VCR PLUS) codes??? (please read)
Message-ID: <[e-mail]>
Date: 6 Jan 93 17:46:39 GMT
References: <[e-mail]> <[e-mail]>
Sender: [e-mail]
Reply-To: [e-mail] (Curt Welch)
Organization: KCW Consulting
Lines: 45

David Sternlight writes:
>Back then, I noticed that two
>sources of published codes, the L.A. Times and TV guide occasionally
>had different codes for the same program, which suggests other
>than a central source. (They weren't typos, and both worked.)

[e-mail] (Carl Oppedahl) writes:
>I trust that readers of this group have no trouble figuring out why
>this would happen -- right?

>The VCR+ people provide programs to the LA Times, and to TV Guide,
>that are not identical.

That's a good theory, but I doubt it's correct.  I've checked hundreds
of codes from many different publications and I've never found two
different codes that mapped to the same show.  Our 6 digit algorithm
produces a perfect 1 to 1 mapping of numbers to shows for all 6 digit
codes, so there's no way Gemstar could have different programs
producing different numbers.

Part of the success of the VCR Plus+ system is due to the length of
the codes being very short.  Gemstar bent over backwards to reduce
this as much as possible.  This was the key weakness in the code that
made it so easy to break.  If they allowed multiple PlusCodes to map
to the same show (so they could tell who encoded it) then it would
make the codes longer.  I doubt they did this.

Sometimes, the same show
will have different numbers because the different guides will be using
different channels (which they expect you to deal with using the channel
mapping function of the VCR Plus+).  But you can see this when you punch
in the numbers because it shows you the channel.

If you punch in two different numbers, and it seems to map to the same
show and same channel, then the difference is probably in the duration.
This has been the case every time I've found two different numbers
for the same show.  It will typically be for shows when strange
durations or start times.  On guide might use a duration of 1:50 and the
other will choose 1:55.

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