[mythtv-users] Strange problem with local PBS SD station (OTA)

Tom Dexter digitalaudiorock at gmail.com
Tue Jan 22 02:48:51 UTC 2008

On Jan 21, 2008 2:56 PM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> On 01/21/2008 02:17 PM, Tom Dexter wrote:
> > On Jan 21, 2008 2:07 PM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> >
> >> On 01/21/2008 02:01 PM, Tom Dexter wrote:
> >>
> >>> I'm in central NJ.  There's a DTV PBS station literally a few towns
> >>> from me (WNJB-DT 58-1) that I've always been able to get in myth on my
> >>> HD-5500 cards.
> >>>
> >>> I fairly certain they used to broadcast in one of those odd widescreen
> >>> formats that's not actaully HD, but a low bitrate 1820x1080 broadcast
> >>> with black bars built into the broadcast and 4x3 content.  It appears
> >>> they recently switched to actual SD.
> >>>
> >> Did you rescan your channels?
> > Yes, that didn't help.  I did specify minimal updates however...any
> > reason that should be an issue?  I did see it update that channel.
> First, a disclaimer:  I know almost nothing about DVB capture in Myth
> (and don't really care to learn more than I need to at this point).
> That being said, I would recommend shutting down Myth (frontends and
> backends), doing a database backup (
> http://mythtv.org/docs/mythtv-HOWTO-23.html#ss23.5 ), then doing a
> complete rescan (I would probably delete all capture cards, but you
> could try just rescanning first).  If all that fails, feel free to drop
> your DB and restore the backup.  It's quite possible that it won't work,
> but I tend to have had the best luck doing a "from scratch" rescan.
> (Just please make sure you do the backup.)
> Mike

I may try that if I have to.  From what I can see it appears that DVB
tuning only uses a few things in the database: It uses the mplexid and
serviceid on the channel table.  The mplexid references the
dtv_multiplex table which has the frequency, and I believe the
serviceid is the PID.  I don't think anything else that would be
changed by rescanning actually affects it.  I should be able to use
dvbscan to verify if the current information is the same as what's in
the database.  I'm guessing the frequency on dtv_multiplex is probably
correct as this channel still broadcasts on VHF channel 8.  An
incorrect serviceid might cause what I'm seeing.


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