[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 

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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