[mythtv] Current DVB problems rundown

Daniel Kristjansson danielk at cuymedia.net
Sat Sep 10 17:12:46 UTC 2005

On Sun, 2005-09-11 at 00:43 +1000, William Uther wrote:
> I deleted my channels table and rescanned.  This caused two problems:
>    i) All my channels got new numbers, as they do every time I re- 
> scan.  This is somewhat frustrating as I then have to go through and  
> edit the recordings table to match.  I vaguely remember something  
> going in recently about this, so it may no longer be an issue.
If you don't delete the channels first it won't renumber them.
You can also chose one of several numbering schemes for inserting
new channels too.

>    ii) There are three different DVB-T transmitters in Sydney.  A  
> list is here: http://www.dba.org.au/index.asp?sectionID=22 (Postcode  
> 2034).  They transmit the same channels.  If I do a full scan, then  
> a) the channels table contains multiple copies of the same channel,  
> and b) some of the frequencies are wrong.
As far as MythTV is concerned these are different channels. We could
probably add an option to cull these, but it probably makes sense to
do this after we have the "optimize frequency" stuff written.

>    To handle this I wiped the channels table again, set up the  
> transports manually (just one transmitter, so no duplicate channels),  
> and then did a full scan of existing transports.  This gave me a good  
> set of channels.
Seems like a reasonable solution, though you might just want to delete
the channels and rescan one of the inserted transports.

>    (Data for manual transport setup was here: http://linuxtv.org/cgi- 
> bin/viewcvs.cgi/dvb-apps/util/scan/dvb-t/au-sydney_north_shore? 
> view=markup .  Interestingly, this data was different to what myth  
> had previously discovered when I just entered the frequencies for the  
> transports and left the other settings on auto.  The system seems to  
> be working better now - don't know if it is an update to myth or my  
> more complete data entry.)
The MythTV scan tries to insert everything properly, but we have a
fix-up function in DVBChannel called CheckChannel which tries it's
best to make any manually inserted transport work. By replacing the
invalid AUTO settings with reasonable defaults. If you run with
"-v channel" it will tell you about any changes it is making.

>    iii) None of my channels transmit guide information, so they all  
> started invisible.  This is actually an improvement for me, as 3/4  
> channels in Aus are basically duplicates.  I just made the ones I  
> wanted visible.  Normally I have to turn off 3/4 of the channels  
> rather than turning on just 1/4 :).
This is actually "fixed" in recent SVN. Now it marks them as visible
even if they don't have guide info.

>    iv) I can record fine.  However, I get no liveTV - the frontend  
> shows a blank screen with no signal lock, and the backend freezes.   
> Others want to use the box now, I'll try and post logs later.  This  
> sounds the same as Adam Egger's problem.
Without the logs it is hard to tell.

I don't know if we have anyone in Australia reporting DVB success yet...

-- Daniel

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