Suggested enhancement: fail over to alternative tuner (eg terr rather than sat) if there are too many errors

Martin Underwood

Something that would be useful...

If a recording is being made on one tuner (eg satellite) and there starts to be a lot of errors (greater than some threshold), it would be useful if TVH could try a different tuner (eg terrestrial) if the same channel has services on both tuners. Maybe switch temporarily to the other tuner and keep checking the original one to see if error rate drops, and switch back if it becomes OK. You might end up with several different .ts files, because the resolution and the number of streams may be different between sat and terr (in the UK, sat tends to be 704x576 and terr tends to be 720x576, and sat has teletext subtitles in addition to the DVB ones) but it's better than a great big gap in the recording. It depends on the other tuners not being committed to recordings at the time, so it would have to be on a best-endeavours basis.

I thought of this when I was recording from satellite the other day and there was suddenly a monsoon-level downpour for about 10 minutes. When I looked at the recording later, there was a 10-minute burst of droupouts in the recording. Now I actually appreciate the warning "satellite reception can be affected by heavy rain".

Of course, the alternative, for important recordings, is for me to schedule two simultaneous copies of the recording, one on satellite and one on terrestrial ;-)

DaveH

> Of course, the alternative, for important recordings, is for me to schedule two simultaneous copies of the recording, one on satellite and one on terrestrial ;-)

Indeed. For most 'interesting' programmes I find they are broadcast more than once. Either there's a +1 channel, or a repeat a few days later, or both. My main PVR - a Humax - automatically tries to record a second broadcast if there are problems with the first recording. I can't remember whether TVH does that as well, sorry.

Saen Acro

https://tvheadend.org/d/5755-howto-catchup-iptv-a-k-a-1-hour-tv-in-work

DaveH

Not sure that helps with a broadcast transmission, rather than IPTV, where the problem is transmission errors.

You need to be able to record a good transmission in order to make a +1.

Martin Underwood

> Not sure that helps with a broadcast transmission, rather than IPTV, where the problem is transmission errors.

Yes I was thinking of something in TVHeadend itself which monitors the tally of Data/Transport errors as a recording is taking place and automatically schedules an immediate parallel (*) recording from a different tuner (on a different network, ie satellite if the failing one is terrestrial, or vice-versa) if the number of errors exceeds a threshold. Just a thought. I imagine it could be done with a few "hooks" into the current stats for the recording, the EPG, the recording-scheduler and the channel-to-service mapping to determine which service on one network is the same as one on the other network that's failed.

I think all the talk of external modules such as ffmpeg is a red herring.

(*) As opposed to scheduling a recording of a repeat at some unspecified time in the future. The reschedule-in-the-future functionality already exists for failed recordings, but it rather depends on therebeing a repeat in the EPG. I'd been waiting a year or so for a certain series to be shown again on ITV3, because I'd seen it when it was first broadcast but had never recorded it, and I finally spotted it, with each episode being shown just once. And being a belt-and-braces chap I scheduled one recording on TVHeadend on satellite and another on NextPVR on terrestrial, on my laptop. And it was one of those rare occasions when satellite went loopy, so I was glad I had the terrestrial recording.

DaveH

I think the problem is that the broadcasts are not necessarily exactly simultaneous, as well as being different formats. So if you switched on detecting an error you'd be pretty much guaranteed to have some disruption. Since you require both tuners to be available for such a recovery to work, I think it is simpler to record both broadcasts in their entirety every time and just delete the unneeded backup straight afterwards if it's not needed.

Even just on terrestrial, there are slightly different timings between BBC1 and BBC1 HD, for example.

That's actually the prime reason I set up TVH, as a backup to my Humax. But it's also sometime useful because it has four tuners whilst the Humax only has two, so I can record extra things without arguing with my wife :)