Failed to be awake for recording - why?

[jcjefferies]

I have checked my Vista NextPVR server and it takes just 3 seconds to sleep so that is a very small window to miss a Wake! I thought it took longer than that but recently I have been ruthless stopping unnecessary Windows services so perhaps that helped.

[imilne]

I have checked my Vista NextPVR server and it takes just 3 seconds to sleep so that is a very small window to miss a Wake!

I don't think that's the issue though.

Let's say you had a recording set for 20:00. NPVR will set a wake-up event for 19:58, 2 minutes beforehand. I believe this is to give the PC time - for want of a better phrase - to get its shit together before the actual recording starts. Perhaps hard disks/NAS units need time to spin up, or dodgy PCI tuners need reset, etc. This 2 minute window is a good thing.

Now let's say you had a 5 minute sleep timeout on Windows, and you stopped using your PC at 19:54. That means it would go to sleep at 19.59 (in 3 seconds or otherwise). It would still be awake during the wake-up event (and nothing happens), but then goes to sleep before the recording starts. Recording therefore stuffed.

Iain

[johnsonx42]

yes, Iain has it. The scenario jcjeffries describes (wake request happening during sleep transition) is a much smaller part of the problem, though many PC's take a little longer to sleep than only 3 seconds. That's why I said a second wakeup request at recording time would solve 90% of the problem; it's probably more like 99%+ honestly.

[imilne]

Maybe a simpler solution is for sub to poll Windows' do-not-sleep API fom 19:58 onwards, rather than only when the recording starts? A second wake-up at recording time is probably a good safety net too though, as goodness knows who wins if sleep time = wake up time (exactly).

Iain

[johnsonx42]

I suspect a second wakeup is one line of code, while adding logic to start hitting the do-not-sleep API 2 minutes early means bigger changes in more places.

[McBainUK]

So, what's the conclusion? Is there a way to avoid "bad timing" incidents like this?

[jcjefferies]

I think that last night as I shut down my client it asked me if I was sure because a recording was due to start soon. Perhaps it was because I shutdown via the System plugin but NextPVR was aware that a recording was due soon. Instead of sending a second wake another option would be for NextPVR to stop Windows sleeping if a recording is due to start in 10 minutes or less.

I am not aware of it happening to me for over 6 months but unless it is a very important recording you may not be aware that it is missing. I think I was first alerted to the problem when I found I only had the last 15 minutes of a 60 minute recording. The computer woke to start a later recording so also made a late start on the previous recording. Further investigation showed an earlier recording finished at 10 minutes to the hour and slept at 5 minutes to the hour, the same time it should have woken.

As programmes start and finish times are in increments of 5 minutes, by monitoring your computer Wake and Sleep times it may be possible by changing the padding slightly to reduce the small chance of it happening even more.

[vintdiesel]

Ohhh, I have had all sorts of issues with sleep, won't-sleep etc. (yes the PC), and I blame it on Windows, so I "manually" handle it otherwise recordings have got missed or chopped.

Typically I use win7 task scheduler to wake the PC every day at 5:50pm for the news at 6:00pm. I use to use a utility "Wake up on Standby" to do the same job but this now supercedes that. I think sub had later reliably got the PC to wakeup just before recording which helps if the first recording of the day is before the news, though that isn't often for me.

Next I don't let windows sleep my PC on inactivity, to that is set to "never" in my power settings.

What I do though is postprocess to transcode my evening recordings from midnight into the small hours. After the last transcode then I call for computer to sleep well before the next recording cycle.

I know it suits me who mostly records in a regular time (the evening) every day, but it's very reliable that I don't get a cut or missed recording. I do seem however to occassionally find the PC still awake after the last transcode for some reason, but it isn't a drama compared with the PC "sleeping in".

[mvallevand]

If NTray was fixed to work on a client, couldn't it be modified to react to block system sleep for the 5 minutes before a recording?

Martin

[imilne]

I wonder if I could put this into the System plugin? Not to block the user if they try to shutdown, but just to inhibit the timed sleep if it occurs in those few minutes before the recording starts.

Iain