[mythtv] DVB Stability problems with watching live TV

Bill Coghill bill at bcd.cx
Mon Aug 9 07:42:02 EDT 2004

Tim Ansell wrote:

>On Mon, 2004-08-09 at 18:42, Damian Ivereigh wrote:
>> <>Hi guys,
>> Has anyone else experienced stability/crashing problems when watching
>> Live-TV with DVB cards?
>> I have been using mythtv with a couple of Australian Nova-T DVB cards
>> for the last few months. The recording and playback works great, rock
>> solid.
Sydney calling !!

>> <>However I have found a couple of wierd problems when watching live TV:-
>> 1) When switching channels, sometimes the player never gets up to speed,
>> staying at that slow speed it uses when trying to get the video and
>> audio in sync.
>> I have experienced this problem. It only ever seems to happen on Channel
>> 7. I'm in Adelaide, South Australia and am using a Vision Plus card.
I have noticed that Channel 7 does something with the resolution and you 
will often get temporary lockups or 'lego' pictures when these 
resolution changes occur.  My logs show this as a change from 720 576 to 
704 576.  Appaerently this is due to the D1 and D2 digital encoding 
having slightly differing resolutions.  I have had it happen a lot 
during ad breaks or promos.  Very annoying - it makes it practically 
impossible to record anything on Ch 7.

I am running an AverMedia DVB-T card with the DVB kernel drivers (1.1.1).

Also with the latest CVS (as of this afternoon) I get mighty odd 
interlacing artifacts on SBS, it seems like alternate lines are from 
different frames, so the picture is might odd - might try to frame grab 
a shot.  This is with the BOB deinterlacer (I also tried the other 
filters after appling the patch to get the full image showing, but the 
BOB seems the best)

>>2) When the signal quality is a bit flaky (and the card temporarily
>>loses sync), I have seen both the front and backend crash (at different
>>times). I realise that the solution is to fix the signal quality, but I
>>would prefer myth to handle this situation a bit better.
>I have also experienced this problem. Sadly it seems signal quality is
>kinda lacking here in Australia, which is the whole reason I went
>digital instead of Analog.
>>I am not looking for a fix (unless someone has one), rather to know if
>>anyone else has experienced it. If so I will have a go at debugging and
>>fixing it.
>>One simple change I would like to make is make the timeouts *much*
>>shorter. Right now if you unplug the aerial, mythtv hangs for almost a
>>minute. Frankly if you can't get sync in 5 secs, you may as well give
>>up. What would be great would be an error message and allow you to
>>change to a new channel.
Amen to that !!  Where did I put that C++ book ?


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