[mythtv-users] Guidance for phase 9

Robert Kulagowski rkulagow at gmail.com
Tue Aug 13 19:22:07 UTC 2019

As one of the people that work for Schedules Direct, (and who's been
dealing with the various re-pack frequency updates for the past few
months), I think the one thing that I've noticed about MythTV versus
other applications is that MythTV seems very tied to matching on
callsign or frequency vs. the ATSC major.minor values.

Gracenote uses a structure of "WABC-DT" is 7.1 and stationID 10001,
"WABC-DT2" is 7.2 and stationID 10002, etc. So even if _the station_
is sending "LAFF" in the PSIP for 7.2, Gracenote isn't necessarily
going to have that in their data, because keeping up with the
thousands of stations in the US alone is hard enough. Both the
DataDirect (legacy feed) and the JSON API include uhfVhf data, but at
least in the JSON API I merely consider those as "hints", because not
all stations inform our upstream that they're going to be moving

Very, very few stations actually change their PSIP / virtual channel
numbers. So even if WABC changes from VHF 7 to UHF 35, they're still
going to be "7.1" for historical reasons.

Other applications appear to perform the scan and the link as two
separate functions. The actual scan from the hardware is blindscanning
each frequency and pulling the ATSC major.minor, the station's idea of
what the callsign is, and the "program number" (So WABC-DT might end
up as "ABC", "7.1" and then program 4 on UHF 35). Phase two takes the
data from Schedules Direct (JSON or XML) and then attempts to match
our 7.1 -> stationID 10001 mapping with virtual channel 7.1 from the
hardware scan. And since the virtual channels numbers rarely change,
then things like re-pack aren't as fraught with panic!

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