[mythtv] MythTV DVB Implementation (What's needed & What's not)

Mike Wilcox mike at trouble.org.uk
Fri Sep 12 15:06:04 EDT 2003

Edward Wildgoose wrote:

>>I'm trying to figure out everything DVB related that is required
>>to match or even superseed comercially available boxes.
>1) Do we actually have to move the setup "to the frontend"?  Actually it should be possible to run the setup program from anywhere (perhaps with a few mods), since it is only modifying the DB.  However, once we are going to be doing preview tuning and auto scanning for hardware then we certainly will need at least some limited access to the backend.  The user would still need to know to setup the mysql.txt on the backend though
I can see the preview tuning being a useful feature, probably for 
non-DVB tuning too!

>2) Mythfilldatabase is a tricky one.  Seems that the process at the moment for analogue users is to setup card, inputs and location, then run mythfilldatabase which sets up the channels table (either automatically, or by prompting).  Suggest then that mythfilldatabase needs to be split into the bit which fills the channels table (for North American users only?  Cable users?) and the stuff which reads in program info.  The point is that the list of channels available via XMLTV seems to drive setup for some input types (analogue), but not necessarily for DVB.
Particularly important where a user has multiple cards, but the channels 
received are in two (or more) slightly-overlapping sets. Ihaven't tried 
getting an analogue card to work alongside the DVB one yet...

>3) What else do we get by moving setup to the frontend though? (As in mythfrontend, not just being able to run on diff PC).  Presumably each card and backend will need different setup for satellite?  Just want to be careful that the user is not confused about the mapping between channels/cards/backends/etc.  Actually, I dont have a satellite connection, and I really don't understand all the permutations at all...
>4) What problems are there with the "scan" application in terms of doing fully automatic tuning?  For DVB-T at least, then it works perfectly (and when it doesn't this should be fixed by fixing the scan app).  Presumably for sat you need the dish params setup, but after that can it just scan away to find everything?
For the scans I have done recently on DVB-T, the config isn't completed 
correctly for channels that aren't currently broadcasting. The channels 
are identified, but the video & audio PIDs come out as 0, and you have 
to hand-craft a config together from scans done at different times of day.

If we want to do something fully-automatic, we'd have to  have something 
in the backend scanning & retrieving PIDs  regularly.

Similarly, I also get the feeling that the channel configuration, at 
least for DVB-T but probably the others too, changes fairly frequently. 
Shouldn't the system be able to cope with channels that appear, 
disappear, or change configuration? Perhaps the backend should have some 
channel-polling function running when the card isn't used for 



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