[vdr] VDR automatic channel update and recording annoyance.

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Mon Apr 4 00:18:00 CEST 2005

Rantanen Teemu wrote:
> Klaus Schmidinger wrote:
>>I've said it before, and I'll repeat it: it's the broadcasters' fault!
>>The PIDs must be set correctly _before_ a broadcast starts!
> I asked once already, but you gave no answer.

Sorry, I had only very little time lately to go through the VDR ML messages.
There are still plenty of them in my inbox...

> Could you please tell me
> where in the DVB standard this is said, so I could reference it when I
> report this to the broadcaster.

Well, I can't quote a standard here, but I would say that plain common sense
dictates that the PIDs should be set correctly (including language codes)
_before_ a broadcast starts. After all, they're not likely to change right
in the middle of a movie, are they? And with _before_ I'd say something in the
area of a few seconds (like 5 or 10 or so), not just a few milliseconds.

But then again, most broadcasters don't even get the running status in sync
with the actual broadcasts, so how can we expect the PIDs to be set at the
right time. Seems to me like there are a few monkeys sitting at a switchboard,
plugging in cables randomly and every once in a while hitting the right spot ;-)
I always thought that in today's digital playout centers things would be completely

> PS. Can PMT_SCAN_TIMEOUT have something to do with the fact that the PID
> change always happens few seconds after the program has started?

This timeout is only to make sure we don't wait too long on a PMT that
isn't actually broadcast. You could add some logging to that 'if' branch
to see whether it gets triggered by lastPmtScan being set to 0 or by
an actual timeout (i.e. 'time(NULL) - lastPmtScan' being only a little
more than PMT_SCAN_TIMEOUT).

cPatFilter::Process() does handle only one entry at a time, but I would
assume that it works fast enough. You could, though, add some debug logging
to see how long it actually takes until a change in PIDs is realized.


More information about the vdr mailing list