[opendtv] A kinda funny CGMS tale
- From: John Willkie <johnwillkie@xxxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 9 Jul 2008 13:21:32 -0700 (GMT-07:00)
First, the background.
The sainted furst customer of my PSIP generator is KYES-DT Anchorage, AK, which
is controlled by Jeremy Lansman (a legendary community radio pioneer and
engineer) and his wife Carol.
Jeremy is a home-grown kind of guy. You can do a google search and see quite a
few posts about him, including stuff from RalphMag.com, a web site run by his
friend and former partner Lorenzo Milam. I haven't talked with Lorenzo in a
few decades, but his legend is even bigger than Jeremy's. Some of this is
chronicled in Lorenzo's 'Sex and Broadcasting', which only lightly mentions
their creation of KFAT (now KPIG-FM and a whole new musical format, Americana.)
Jeremy brags about the fact that he put his FSTV DTV station on the air using
used equipment bought on Ebay. (However, he couldn't buy a PSIP generator that
way, which is how we came to work together.)
Jeremy's station is a commercial broadcast station, with network (MyNetworkTV,
after the demise of UPN) and and syndicated programming. He has built or
assembled everything, except the code in the PSIP generator.
He takes non-pathfire programming down from satellite in analog and captures
the content to standard-off-the-shelf DVD burners. The disk's MPEG-2 video
output is then converted to analog and aired directly. (This will change a
bit, I hope, when analog sunsets.)
Jeremy doesn't have a caption generator, and isn't required to generate
captions, but under the rules he has to pass on captions that are alerady in
his syndicated and network programming. This is a bit of an issue between us,
since a PSIP generator, to be in-spec, needs to assert the
caption_service_descriptor in the presence of captions, and to not transmit it
in the absence of captions. Jeremy has no way of detecting captions. But --
thanks be to the MPEG-2 gods -- when he captures analog programming with
CEA-608 captions, his setup transmits CEA-608 captions.
I also need to mention that his Lucent ATSC encoder puts illegal (due to an
extra byte) rc_descriptor into his digital programming (three video/audio and
three audio/only) channels. The video/audio channels are also on DirecTV and
DishNetwork.
Jeremy and I are at different ends of the political spectrum, which makes for
lively discussion. He did like my "Empress Pelosi" in a conversation the other
night, and when assured that I hadn't first heard it on Rush Limbaugh's show,
he asked if he could use it.
In that conversation, he mentioned that he was getting come telephone
complaints from people that were having trouble recording certain television
programs. Of course, if the rc_descriptor were as Bert the dilletantish fool
and foil sees it, nobody would ever be able to record any programming, since he
will be asserting the rc_descriptor until he gets around to having my PSIP
generator generate MPEG-2 PSI as well as PSIP, taking the PSI subsystem of the
Lucent out of the stream.
Did I mention that EtherGuide Emissary has been operating faultlessly at
KYES-DT for more than 62 days in a row, generating reliable PSIP every second,
and not skipping even a beat when we upgraded the output to use the new form of
the AC-3 descriptor a few weeks back? Anyway, so much for the advertising part
of this posting.
"That's a CGMS problem," I noted, "but if the distributor is sending the CGMS
flags, how do you even record the programs?"
"They must be sending it as 'copy-once'", he said, and my DVD copy counts as
that first copy.
The work-around to this, of course, is for his station to acquire a working
caption generator (we've gone round-and-round on this point) and to strip out
the CGMS bits (at least for television programs where he can do that pursant to
the contract.) There will be hell to pay if anybody transmits syndicated
programming to him with CGMS set to "copy never", since he may not be able to
burn the content to DVD.
So, this is a long-way-around to point out that, unlike Bert, I actually do
have experience with diagnosing such issues, and I know for a fact that the
rc_descriptor does not prevent the recording of programs, but that the CGMS
bits can and are used for that purpose, and that they can exist even if the
programming in question was of entirely analog origin.
John Willkie
EtherGuide Systems
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