[mythtv-users] DVB EPG in MythTV?

[Joe Votour]

Newer SVN versions of MythTV apparently do support
pulling in data from the DVB program descriptors (I
live in North America, where DVB isn't available, so I
can't comment on how well it works).  I have done some
DVB-related work for my employer though, so I do know
how the system works.

The EIT is the "Event Information Table" (if I
remember my TLAs correctly).  The DVB specification
supports sending lots (and I mean lots) of information
within it (the basics such as show start/end times,
program name and genre, but also things like complete
cast lists, MPEG format information, etc.).

The way it works is that within the MPEG-2 stream that
is received by your DVB card, there are video, audio
and PCR (timing) PIDs for one or many "channels",
there are extra PIDs that are added in by your
provider (or may come from the original satellite feed
- regardless of how they got there, they are there). 
A DVB card can listen on these PIDs and capture/parse
the data, and turn it into program guide entries. 
Most of it is TLV-type (type, length, value) data with
a fair amount of ASCII text.

As I said, I don't know the specifics of the EIT
processing within MythTV, but I would suggest that you
stick with the tv_grab programs if you get accurate
data from them.  The reasons that I suggest this are:
1. With the DVB streams that I have seen, the program
guide information within the DVB stream is only good
for 1-2 hours (typically, you get the "now" and
"next", the currently showing program, and the next
program).  This means that it will be difficult to
plan far ahead in the future for scheduling, since the
data just won't be there.
2. In order to get complete EIT data, your DVB card
will likely need to hit multiple frequencies to
capture the EIT data on those frequencies.  If you
have a single card and aren't recording, this won't be
an issue, but if you're recording back to back shows
and only have a single card, you've got nothing to
tune to other frequencies to find the EIT data.  In
that case, you're missing program guide listings.

Again, this information doesn't come from the MythTV
implementation (I've implemented this in the past, and
it's quite painful), but comes from my knowledge in
the area.  YMMV, depending on what kind of hardware
you have, and how much program data you want (I'm
quite happy with DataDirect, and having about 10 days
worth of listings).

-- Joe

--- Jakob Fix <jakob.fix at gmail.com> wrote:

> Hello,
> 
> I've heard that Myth should be capable by now to
> retrieve EPG data
> from the DVB stream.  There seems to be quite some
> talk on the dev
> list.
> 
> Is this correct?  If so, which version of Myth
> should one have in
> order for this to work?
> 
> So far I'm using tv_grab_dvb which works fine
> although it has some
> problems with timezones, and it only gets the
> current channel's
> transport stream's EPG data.
> 
> Oh, and what does EIT mean, and what's the
> difference with EPG
> (wikipedia was no help here)?
> 
> --
> cheers,
> Jakob.
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
>
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> 



		
__________________________________ 
Yahoo! Music Unlimited 
Access over 1 million songs. Try it free. 
http://music.yahoo.com/unlimited/