[mythtv] vps once again...

Martin Moeller martin at martinm-76.dk
Thu Jul 22 18:49:02 EDT 2004

I am not sure exactly how VPS/PDC works, but I believe it goes something
like this:

Your point of reference is the time the show *should* start according to
the listings, say 21:00. Along(?) with that they send a value for when
they think it *will* start (maybe this is only PDC, but I think VPS and
PDC are the same..?). If this is true, then theoretically, MythTV could
cycle the channels set to record that day in 'off' periods and update
its VPS info once in a while (possibly user definable. Something like 15
minutes should be fine I think). 
There must then be a signal of some kind when the show really does start
but if you have recent VPS/PDC data and no conflicts then start
listening for this signal shortly before it is expected (or if
back-to-back, maybe just start recording? I guess that depends on what
you can see from the VBI datastream).

I hope this is fairly close to reality. I only have TextTV to base it on
where some shows alternate listing time and PDC time... :)

fre, 2004-07-23 kl. 00:20 skrev maestro:
> hi lucas,
> here is what jumped to my mind when i read your reply.
> Am Don, den 22.07.2004 schrieb Lucas Meijer um 22:56:
> > Hey,
> > 
> > > btw. does the hauppauge pvr 250 support vbi, as this is mandatory for
> > > receiving vps signals i hope it does.
> > 
> > It does. there is some preliminary support already for it in some of the 
> > more recent ck versions of the ivtv driver. If I have the util output 
> > all vps messages I got about 1 every 20 minutes orso, thats all testing 
> > I've done.
> > 
> > Now to get back on topic, how this would properly intergrate into myth 
> > is harder.
> > 
> > Making a recording stop when receiving the next vps is pretty 
> > straightforward. 
> > But when do you start? In order to receive vps's you 
> > need to be tuned into the channel. So you should already have a card 
> > listening for vps before the show starts. How much before? an hour? 3 
> > hours? a day?
> a trivial solution would be to tune into the channel when recording
> should take place according to epg, and listen for the vps, as the
> recording would take place from then on without vps that sounds ok for
> me. this would miss events when a show starts early, for these cases i
> don't know a propper solution, do you know if this is common practice by
> the broadcasters?
> > 
> > I'm not that fermilier yet with the mythtv code, so I don't know how 
> > flexible it would be to a completely different way of timing when to 
> > start and stop recording. 
> neither do i.
> > It would also be a pain to deal with 
> > conflicts. what if the show goes on longer than expected, moving into 
> > the timespace of another show that was supposed to be recorded.
> i cant see the problem there, this could be solved by a "simple"
> priority scheme like it's allready present right?
> > 
> > what if you start listening for vps an hour early, but you were too 
> > late? you'll keep on waiting for the vps while you could be recording, 
> > only to find out at the next vps that the show is over..
> hm thats a tough one.
> <wild guessing mode>
> 	why not start recording accodring to epg, and chop of the beginning
> when receiving a correct vps? as you mentioned before stop recording
> because of a vps event would be straitforward problem solved?!
> </wgm>
> > 
> > So technically yes, the pvrx50's can receive vps's, but how to deal with 
> > them from a usability point of view is a whole other can o worms.
> > 
> > Looking forward to bright ideas people might have on this topic.
> > 
> > Bye, Lucas
> > 
> > ______________________________________________________________________
> > _______________________________________________
> > mythtv-dev mailing list
> > mythtv-dev at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
> ______________________________________________________________________
> _______________________________________________
> mythtv-dev mailing list
> mythtv-dev at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev

More information about the mythtv-dev mailing list