[mythtv-users] known issues related to DVB-T in Australia (was: Channel tuning broken in 0.24)

[Karl Dietz]

Hi Igor,

I'll write together the issues that I'm aware of for DVB-T in Australia
in case you or other Australians are ready for some patch testing or
even looking for some code hacking to do :-)

As you are on Mythbuntu you can build your own patched packages and even
setup a PPA to share them with fellow testers very easily, see
http://www.mythbuntu.org/wiki/recipes

On 31.05.2012 03:45, Igor Cicimov wrote:
> Before rolling back to 0.23 I'll try to check the card performance
> outside Mythtv. In meantime, any suggestions to solve this highly
> appreciated.

There is at least two known issues with MythTV and DVB-T in AU.

One is that the channel scanner stores the center frequency instead of
the offset frequency of the transports which makes successful tuning
harder depend on the quality of your DVB-T frontend.
http://code.mythtv.org/trac/ticket/9777

Another is that the channel table in MythTV only contains the +125kHz
offset but some transmitters seem to use a +167kHz offset.
https://github.com/MythTV/mythtv/blob/master/mythtv/libs/libmythtv/frequencytables.cpp#L336
changing the two instances of
DTVModulation::kModulationQAMAuto, 125000, 0);
into
DTVModulation::kModulationQAMAuto, 125000, 167000);
or
DTVModulation::kModulationQAMAuto, 125000, 166667);
might help with that. (A user wanted to test it and report back on IRC
earlier)


With general DVB there was some issue with channel scan that got fixed
for 0.25.

The scanner didn't work well with segmented PAT/SDT tables. This fix has
improved channel scans alot for me on DVB-C.
http://code.mythtv.org/trac/ticket/10054


Some unfixed issues with EIT have patches that you could try.

The scanner sometimes not finding the ONID/TSID has already been
mentioned.
http://code.mythtv.org/trac/ticket/10217
To get at least EIT, should you use that, you can try the patch from
http://code.mythtv.org/trac/ticket/10784
To improve the quality of the EIT data you can also try
http://code.mythtv.org/trac/ticket/10098


And I already worked on the broken channel.conf import, but didn't get
it working and moved on to higher up stuff on my list.

The channel.conf import is known broken for DVB due to not importing
the ONID and TSID.
I have attached a work in progress patch to that ticket, but sadly its
still not working. Might be a starting point for someone who wants to
fix the channel.conf import.
http://code.mythtv.org/trac/ticket/7701


Regards,
Karl