[mythtv] Re: MythTV Crashes on channel change.

Martin Smith martin at spamcop.net
Fri Jul 11 16:10:32 EDT 2003


Ben wrote:

> Yes, I am very much looking forward to that, in case anybody decides to
> implement that. I won't, because it will probably need extensive changes
> to MythTV's core code, including the protocol, and it's not worth the
> time for me personally, it's cheaper to buy more cards.

This is a good point. Some of the assumptions in the system that are valid for
analogue cards don't carry over that well to DVB. I definitely agree we should
get the basics fully working before considering it.

>>Looking at the database as it stands I don't think the scheduler has enough
information available to make this work.
>>
> I specifically wrote the code with that in mind, that the code would be
> able to tune to several channels per card at once. I should work (modulo
> bugs) out of the box, if the other MythTV code is adapted.

> I think the DB schema also is sufficient. You just need to compare all
> the channel tuning parameters. If they all match apart from the PIDs,
> the channels are on the same transponder and you can tune to them amt
> the same time. The decision would have to be made by the DVBChannel
> class, and that's where it belongs IMHO.

I guess my point was more about how the knowledge of what can be recorded
simultaneously is spread around the system. Looking at the current schema
you are correct to say that there is enough information available. What I should
have said is that interpreting it needs knowledge of how DVB works. If we're not
careful this will end up spreading out through the system. 

Other approaches, and I'm not suggesting these are better because I haven't
fully thought them through would be to have some sort of 'channel group' concept
in the db to link shareable channels or to represent these cards as some sort of
notionally separate capture cards that share tuners and video sources. This
could potentially remove a lot of 'if it's DVB then do this ...' code from the
system as it develops.

Anyway, I'm just throwing ideas around here. I'm not criticising what you've
already done.

Maybe recording multiple streams will need too much work to be viable? I could
live without it myself to be honest. I have room for 2 cards but it would
definitely appeal to people with only one PCI slot available.

Martin


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