Recordings stopping within seconds after starting

[zer]

Been getting intermittent issues with my DVB-S dual tuner (Freesat UK) where recording streams appear to start and then just stop within seconds or minutes.  This may be a tuner fault (fairly old hardware now, no more driver updates), BUT NextPVR doesn't seem to even notice that the recording stream has stopped when this happens.  The tuner status and the recordings page in the windows client and web UI all show that the programs are still being recorded / have their expected full length, its only when I try to play them that I know things have gone wrong this way.

Anyway, this occurred with 3 recordings tonight after a fairly reliable run of a few days so I thought it would be a good opportunity to capture the logs (I've also attached the recording ts files themselves as they are so small), in case someone can determine what's wrong or if there's anything can try, short of buying a new tuner card.

Thanks for looking as always.

[mvallevand]

All very low signal strength on the same tuner, check the cables

2020-11-24 20:29:00.140 [DEBUG][4] StartStream(): D:\Recorded TV\Would I Lie to You\Would I Lie to You_20201124_20302100.ts
2020-11-24 20:29:00.151 [DEBUG][4] locked=0, present=0, strength=2, quality=5 (took 16ms to check)

2020-11-24 20:59:00.162 [DEBUG][4] StartStream(): D:\Recorded TV\QI XS\QI XS_20201124_21002115.ts
2020-11-24 20:59:00.173 [DEBUG][4] locked=0, present=0, strength=5, quality=5 (took 0ms to check)

2020-11-24 20:59:00.191 [DEBUG][5] StartStream(): D:\Recorded TV\Masterchef The Professionals\Masterchef The Professionals_20201124_21002200.ts
2020-11-24 20:59:00.200 [DEBUG][5] locked=0, present=0, strength=5, quality=5 (took 0ms to check)

[zer]

Hmm, the thing is I don't really have signal/quality issues for programs recorded with this tuner. The ones that don't stop almost immediately like this are "perfect" with no stuttering or picture break-up throughout the whole recorded program.

Compare that with my DVB-T tuner (on a traditional aerial) where the signal IS really bad right now, recording streams NEVER stop like this but instead I have to put up with stuttering and picture break up every few seconds throughout the entire recording.

If signal strength were to blame for this issue (stopping the stream entirely), then I'd expect ALL of my recordings on that tuner to stop prematurely as its unlikely the problem would not occur during the typical duration of a program.

[Graham]

If signal strength were to blame for this issue (stopping the stream entirely), then I'd expect ALL of my recordings on that tuner to stop prematurely as its unlikely the problem would not occur during the typical duration of a program.

Check the device log and find "strength=" and "quality=" values for recordings (or Live  TV sessions) that work well and that don't work well ... Do they vary?

[zer]

OK I'll monitor that more closely as this continues to happen. Looks like this measurement only takes place right at the beginning of the recording? I'm suspecting some interaction issue between the two tuners (other tuner was active, second tuner may have been required to switch polorisation on the LNB and perhaps failed to do that in good time).

To my more generic question - why can't NextPVR detect that the recording has failed to start (and ideally take remedial action)?

[Graham]

To my more generic question - why can't NextPVR detect that the recording has failed to start (and ideally take remedial action)?

The simple answer might be that NextPVR copies the incoming stream from the tuner to a file on disk ... and can never be sure that content of the incoming stream is "correct" or not.  For example, in the UK there are part-time channels that start braodcasting at a specific time and the incoming stream on these channels might be "empty" before the channel start time.  NextPVR does not know why the stream is "empty" and does not know whether there is a problem that needs remedial action.

I expect that Sub has a more sophisticated answwer.

[sub]

For example, in the UK there are part-time channels that start braodcasting at a specific time and the incoming stream on these channels might be "empty" before the channel start time.  NextPVR does not know why the stream is "empty" and does not know whether there is a problem that needs remedial action.

That is absolutely correct. Lack of any data for a channel isn't always a sign of a problem.

NextPVR does detect some other types of errors when a recording starts, and can retry on a different tuner, or reschedule for some other time, or at least note the error in the recording. Ultimately there is only so much it can do though - it really needs to be able to depend on a signal to being available before it can capture data.

[zer]

Been all fine again until last night when it happened again with the same two programs that were scheduled for the same time on the same tuner. Again got "locked=0, present=0, strength=5, quality=5" for both.

I was thinking it must be more likely to occur in the case two recordings are starting on the same tuner at exactly the same time (and the other tuner on the same device is already recording, possibly). However I cancelled these and manually re-scheduled recordings to start at the same time on those same channels and both started fine. So still investigating when I see it.