DTV Signal Monitor needs to check PMT for on-air-status

[stuarta@…]

I've been testing for the last few days.

rev 7064 + signal monitoring patch.

This fixes problem 3 in the list.

When testing case 2 I was able to watch the other channel which timeshares with the channel that went off air, although I was tuned to the logical channel that was off air. I'm happy to leave this part as resolved for now, since proper handling of this requires finishing off interactive tv.

(The following I've tested on 7082 + signal monitoring as well.)

What no longer works is case 1. This is because the channels here in the UK logically go off air, but in practice they are still on air. What happens is the PMT is updated from a video + audio stream to only a data stream(s). So the signal monitoring isn't going to help us here.

When the backend starts up on one of these "off air" channels, it can still get a valid signal lock, but there is no TV service present. There used to be a check in dvbchannel.cpp

if (!chan_opts.pmt.OnAir?()) {

ERROR(QString("Channel #%1 is off air.").arg(chan)); return false;

}

This did pick up this case. We will need to check something like this when entering live tv.

[danielk]

(In [7101]) Fixes #231.

Added check to make sure we have both video and audio pids in PMT for DVB recordings.