[mythtv-users] Cannot get EIT and picture data on same channel

Philip Allison slightly at pathetic.co.uk
Thu Jan 25 18:37:20 UTC 2007

> I don't know if this is a given or not. I mean, I've seen poor
> digital reception cause dropped frames and blocky mpeg artefacts.

Well... yes, true. It's not as black and white as I suggested, this was an
exaggeration, but it just seems to me that there's something fundamentally
fishy about its current behaviour. At the moment I'm not calling anything
a bug in MythTV (which is a fine project, and doing exactly what I want in
all ways bar the program guide), because I don't have any evidence I could
base it on.

> These are quite visible, and indicate that "some" of the signal is
> being received but not "all of it". Isn't it possible that at one
> frequency one might get a decent picture but poor reception cause the
> EPG to fail? I admit that it seems less likely that a poor signal
> would cause only EIT data to be received, but I'm really not
> qualified to say.

Neither am I, hence the questions. :) No offence to yourself, you're
clearly offering what help you can, but does anyone else who might be
reading this have anything more concrete to add?

> I read <http://www.gossamer-threads.com/lists/mythtv/users/
> 245481#245481> that with the ivtv driver it's possible to `cat /dev/
> video0 > test.mpg` &amp; `mplayer test.mpg`; is this possible with your
> card?

Not directly, no - there might be some equivalent test, but I'm honestly
not sure. I have "/dev/dvb/adapter0/", containing "demux0", "dvr0",
"frontend0" and "net0". These either output nothing or aren't accessible
with a simple cat, so I assume they aren't suitable for streaming from
directly in that way.

> I think this would allow you to view the channel 1 - is it
> jittery or blocky? - and maybe there tools that would allow you to
> try extracting the EPG data from channel 541.

Within MythTV itself, there isn't even a bad picture on channel 1, there's
simply no signal lock. Will have a search for EIT tools and see if I get
anywhere; does anyone else know of any off-hand?

Just to confirm something, dvbscan itself also detects duplicate channels,
some of which aren't viewable (using xine); I notice MythTV doing what I
take to be duplicate detection during its own full scans, the trouble
being it seems to keep the lower-numbered copies, which 9 times out of 10
are the non-viewable ones.

> I wasn't having trouble - I did understand your description of your
> symptoms. But I wasn't able to offer any better help, and seeing as
> no-one else had replied I thought that (if nothing else) my comments
> would give you a "bump".

I apologise for my tone in that sentence; I suppose I misunderstood your
own tone in your original reply. I'm not normally confrontational. :)

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