[mythtv-users] is (clearqam) channel scanning idempotent?

Eric Sharkey eric at lisaneric.org
Wed Aug 3 11:52:43 UTC 2011

On Wed, Aug 3, 2011 at 7:11 AM, Brian J. Murrell <brian at interlinx.bc.ca> wrote:
> So, assuming the channel scanning goes well, will the channel name and
> xmltvid associations for channel-progid stations remain the same or will
> they all be reset?

If a channel existed in the table before the scan, and the channel
doesn't fail to tune during the scan, then the information in the
table for that channel isn't altered.

Rescanning without first deleting all channels will only affect
channels that are either no longer tunable or are new channels without
an entry in the database.

The last time I did a rescan (about 6 months after the previous scan)
the channel layout was almost entirely different, so I was basically
starting from scratch anyway.  YMMV.

> What does happen to the information for channel-progid stations that
> have been [re-]moved?

Moved channels appear as a deletion and an addition.  MythTV has no
way to know that the channel which was deleted is related to the new
one added, so you need to reenter any information you want to identify
the channel.

> Surely there has to be some easier way to manage all of this (all too
> frequent) clearqam channel re-mapping other than this laborious process
> of [re-]scanning and manual channel-by-channel editing.

The cable providers are perfectly capable of labeling their channels
in a way that a clear qam tuner can read,but if users could just plug
in any old TV and find the channels they want to watch, people might
not rent as many STBs, so they're disincentivized to do so.


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