Diagnosing Continuity Errors (1 Viewer)

[toii]

I have noticed that some recordings are very messed up when attempting to play. I looked in the tswriter log and see thousands of Continuity Error during the recording. Three are about 3-6 Continuity errors per second (18M of errors in one recording!). I am wondering how to diagnose the problem.

I have 3 internal TV DVB-T tuners in the PC. I am only recording unscrambled TV channel. My timeshift buffer is a ramdisk. I have tried manual control of timeshift recording on all 3 tuners and I don't see any errors at all while I am doing this. It says signal level 0 and signal quality 100 (apart from one of the three tuners which says signal qulaity 50 for the first second then jumps to 100 and stays there). I am running Win7 with no antivirus app running. There is no network involved in my setup - everything is on the one box. I am using Kodi as my frontend player. The recrdings that have lots of errors during record also fail to play back properly if I used Mediaportal frontend. I figure the problem is in the process of recording the file based on the errors I see.

I am thinking I could try disabling all but 1 tuner at a time and see if I can isolate to a single tuner or not. Other than manual control to start timeshift on each tuner, what else can I do to try an troubleshoot the problem?

 

[mm1352000]

Hello and welcome

First, thanks for posting all the detail. That helps a lot.

From what you said, I think you're already aware of this. However, for the benefit of other people that might be reading this thread...
The most common causes of continuity errors are:

1. Signal strength and/or quality issues.
2. HDD load, often caused by security software scanning TV Server's install, timeshift, recording, and/or settings directories.

How do you diagnose and resolve the problem?

In short, first thing I would do is check for patterns.
Does the problem only occur with:

• certain tuners
• certain channels
  • encrypted channels
  • HD channels
  • channels broadcast from a certain transmitter
• when timeshifting
• when recording

Usually if you can find the pattern you'll be able to isolate the cause.


Now, back to this specific case...

I have noticed that some recordings are very messed up when attempting to play.

So the problem is only with recordings, and never with live TV?

I have 3 internal TV DVB-T tuners in the PC. I am only recording unscrambled TV channel.

Okay.

My timeshift buffer is a ramdisk

Okay... but presumably you don't use the same RAM disk for recordings?

Is the drive that hosts the recording folder:

• a USB or network-attached drive/share (eg. in a NAS)
• almost full
• being used by other HDD-intensive processes (eg. ComSkip)

Also, are you using the same recording folder for all tuners?

I have tried manual control of timeshift recording on all 3 tuners and I don't see any errors at all while I am doing this.

Would it be safe to assume that you were testing the same channels as you record?

It says signal level 0 and signal quality 100 (apart from one of the three tuners which says signal qulaity 50 for the first second then jumps to 100 and stays there).

Okay. That doesn't fully eliminate potential signal strength/quality issues because:

• we can't be sure that 100 is the maximum value
• for various reasons, readings are not safely comparable between tuners unless they're the same model and revision of tuner from the same vendor
• the readings won't show intermittent/temporal issues

Having said that, for now I'm happy to take your word that your signal strength and quality are okay.

I am running Win7 with no antivirus app running.

Okay.
As above: are you running any other software that could be heavily using the drive that the recording folder is on?

There is no network involved in my setup - everything is on the one box. I am using Kodi as my frontend player.

Okay.

The recrdings that have lots of errors during record also fail to play back properly if I used Mediaportal frontend. I figure the problem is in the process of recording the file based on the errors I see.

Yep, you're correct.

I am thinking I could try disabling all but 1 tuner at a time and see if I can isolate to a single tuner or not.

Yes, that would be a reasonable thing to try.

Other than manual control to start timeshift on each tuner, what else can I do to try an troubleshoot the problem?

I've given some suggestions above. In general you need to find a pattern.
For example, only recordings on a certain channel (or group of channels) have glitches, and that would point to signal strength/quality problems.
You can use manual control to check signal strength/quality and the discontinuity counter.
You can use the performance section of Windows task manager to check which other software is heavily loading HDD(s) during recordings.

 

[toii]

Thanks for the comprehensive reply. I will try to identify the cause using your suggestions.

So the problem is only with recordings, and never with live TV?

I dont normally watch live TV so it I cant be sure about this but I will make a note of when/where if I see it happening.

Okay... but presumably you don't use the same RAM disk for recordings?

Is the drive that hosts the recording folder:

• a USB or network-attached drive/share (eg. in a NAS)
• almost full
• being used by other HDD-intensive processes (eg. ComSkip)

Also, are you using the same recording folder for all tuners?

Correct, the ramdisk is just for timeshift buffer. Recordings are on internal hard drive. There are no other intensive HDD processes that I am aware of but I will try and monitor it when a recording with continuity errors is in progress. All my recordings go in one folder. I am only using one tuner (doing the recroding) at the time that the failed recordings have happened.

Would it be safe to assume that you were testing the same channels as you record?

Yes I have been manually testing with the same channel that I know i have had failed recordings on. I will keep a record of any future failed recordings to see if I can see any pattern.

thanks again for your help

 

[toii]

I think I may have found the problem. I tried manual timeshift on each of the 3 tuners on several channels. The channel from which I know I had some failed recordings was showing about 1% continuity errors on 2 of the 3 tuners (both on same card which use the same antenna cable) but absolutely no errors on the other tuner on a separate card (with separate antenna cable). A couple of other channels also had the same error rate on the 2 tuners on the first card. I tried swapping the cables at the wall socket end and retested and the error rate went up to about 5% on the same 2 tuners but still no errors on the third tuner. I then tried swapping the cables on the back of the tuners and now I am getting zero continuity errors on all the channels on all 3 tuners. It seems that there was a poor connection between aerial cable and socket on one of the cards that resulted in continuity errors but only on some channels. It may be that the error rate went over 5% at times when I was recording or perhaps this level of errors was enough to result in the severe pixelation and broken audio I was experiencing. I will keep an eye on it but I suspect that this was the cause of my problem.

 

[mm1352000]

Nice.

If the 2 tuners on the same card share the same aerial cable, you might want to be aware...
Behaviour may change depending on which tuner(s) are active and which channel(s) are tuned. That's because there'll be a splitter on the card, which may only be activated when both tuners are operating. Such cards tend to require good signal strength/quality to compensate for the on-board splitter and the potential interference issues from the compact RF environment.

Anyhow, I'm glad to hear you've found something.

 

[toii]

Ok, thanks again for all your help. I will keep an eye on it. The guy that fixed up my external antenna said the signal strength was extremely good so hopefully I'll be ok