[mythtv-users] USA OTA FCC frequency rescan?

James Abernathy jfabernathy at gmail.com
Tue Aug 13 16:09:54 UTC 2019

> About mythtv-setup creating new channels or updating old channels.
> In a nutshell it works like this (as I understand it).
> A channel found in a scan is considered an old channel if the
> transport/multiplex has the same frequency and if the ATSC major and
> minor channel numbers are the same. In that case the existing
> callsign, channel name etc are replaced by the values from the scan
> but the xmltvid is preserved.
> This means that if channels, even if they keep the major/minor
> numbers, are on another multiplex after the update they will be seen
> as new channels.
> The callsign is relevant for programming/scheduling/recording but it
> is not used by mythtv-setup for identifying a channel so there is no
> need to edit it before doing a scan.
> If this is not the way that it should be then it is always possible to
> create a ticket with a description on how the channel update behavior
> should be. The question of what identifies "the same channel" needs to
> be addressed there.
> Note that I have not tested this because I do not live in ATSC land,
> but with DVB it works along the same lines, with channels identified
> by network ID and service ID.
> References:
> - channelinfo.cpp:445 function ChannelInsertInfo::IsSameChannel
> - channelimporter.cpp:968 function ChannelImporter::GetDBTransports
> Success with the update!
> Klaas.

Thanks for the information.  I have no idea how the internals work on a 
scan so this is helpful.

Jim A

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