You need seperate "video sources" in the mythtv-setup sense. It's a really crappy name because what they REALLY are is the channel line up and program guide information associated with one or more signal inputs rather than the inputs themselves.

The channel lineups for SDTV and HDTV are different (even if they had the same physical connection, networks and content the tuning information is different). If you associate both cards with the same lineup you're telling the software that they're more or less interchangeable and you'll get the SDTV card trying to tune in HDTV channels and failing miserably as expected. Sort of like you picking up the phone when there's a modem or a fax machine at the other end.

Well, that's exactly what I have at the moment, One zap2-it lineup of SD & HD channels and I select the tuner manually for 'live' TV....

Programmed recordings usually get it right, but sometimes just miss.

I'm not aware of a way to have Myth keep two channel lineups straight, but I'll look into it.
I'll try the proceedure found here: http://mysettopbox.tv/phpBB2/viewtopic. ... el+lineups

If you're not afraid of SQL look around for a posting on my update_database.sh script (that as the search term, me as the author should do it). It shows most of the details needed to monkey with listings for merging (as in my case) or splitting them (as in yours).

OK, I got this going, thanks for your tip-off that it was possible.

I couldn't make two ota lineups in Zap2it until I figured out that I could make two lineups for different zip codes (adjacent, so all the channels were available.) Then I put NTSC channels in one zip code and ATSC in the other.

After that, it was a matter of making two inputs during backend setup, 'antenna' and 'antenna digital', and then associating them with their respective tuners. A few 'scans', 'mythfilldatabases',and restarts, some editing 'junk channels' from 'Mythbrowser' and it's up and working.

Thanks tjc, but I believe I'll defer messing with SQL for a time when it's 'already broke'...