BBC One HD freezes intermittently, watching or recording. (1 Viewer)

mikeyp

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August 23, 2015
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I have an odd problem with MediaPortal 1.15 when watching FreeSat HD, it has done this with every version I've ever had. SD channels are fine. HD channels like ITV, Channel 4 and FIVE are fine. BBC HD channels however seem to crash intermittently. They start watching fine, then begin to break up, before freezing altogether. There is no "no signal" notification, the picture and sound simply break up and stop completely. I've seen people refering to codecs but playback isn't the issue. It does it either watching live TV or when recording. Sometimes it's a couple of minutes in. Sometimes it can run fine for an hour.

For example, this evening I tried to record Monsters University on BBC One HD. It started recording at 16:53 and recorded a little under 2 minutes of video before failing. I tried running MediaPortal Watchdog, and exported the log if it helps. I've also attached a live crash around 19:50 (roughly) though I didn't make an exact not of the time. I'll edit this post and post both logs in a few minutes.

This behaviour doesn't occur on the Freeview HD tuners, but I prefer FreeSat as they broadcast in DD which my AMP works with. It won't decode AAC as broadcast on Freeview.

Has anyone else seen this behaviour and/or know of a fix please?

Thanks,

Michael

Edit: Logs now attached

Edit 2: I realised picking through the logs that one of the tuners on the card wasn't working. The cable had come away. This has now been fixed and is working but was unrelated.
 
Last edited:

mm1352000

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    Hi Michael

    Sounds and looks like a classic signal strength or quality problem.

    There is no "no signal" notification...
    MP only shows "no signal" notifications if tuning (ie. starting to view the channel) fails due to a signal problem. There'll be no notification if signal drops out after tuning succeeds.

    ...the picture and sound simply break up and stop completely. I've seen people refering to codecs...
    Your description of what happens is a typical codec response to a stream with lots of corrupted or missing chunks, so it's no wonder you've seen codec references.

    For example...
    Both the recording and live TV attempts show the same symptoms: a ton of continuity errors in the TsWriter log file.
    Search the forum for references to continuity errors and you'll find the top 3 causes are:
    • signal strength or quality problems - either signal too weak/bad, or too strong
    • HDD that hosts the time-shift/record folder overloaded by other programs; usually it's some kind of security software that decides to scan the time-shift or record files as they're being written
    • driver DPC latency problems
    There are other possible causes, but they're generally rare and very technical.

    In my opinion based on the information you've provided so far, you have signal strength/quality problems.

    Yes, it is possible for you to have a signal problem that only affects the BBC HD channels. The technical explanation of why it's possible is time consuming, so I won't go into detail unless you specifically ask me to.

    My suggestion to you would be:
    1. Open TV Server Configuration.
    2. Go to the manual control section.
    3. Select your Freesat BBC One HD channel and start time-shifting.
    4. Watch the "discontinuities" (which is the number of continuity errors), signal strength, and signal quality figures.
    Normally the discontinuities figure should normally stay as zero and/or not change.
    When your problem is occurring, you'll see the discontinuities figure increase rapidly/consistently.
    My prediction is: at the same time as the discontinuities figure starts to increase, there'll be some kind of change (eg. a drop) in either (or both) signal strength or signal quality. This would be one way of confirming the signal problem diagnosis.
    Note you can do the same test for other channels (eg. ITV HD).
     

    mikeyp

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    Thank you for your quick and detailed response.

    Interesting. I figured as much about the codec response. What's peculiar is the way it simply dies and does not recover as you may see with a poor signal. Let me expand on your points to see if that helps...

    • I guess it could be a signal strength issue, but I think that unlikely. I moved house in July and the problem followed with the machine to the new satellite dish unchanged. Signal quality and strength is pretty decent as you'll see in the screenshots in a minute. Let me know what you think.
    • It is possible the hard drive is causing the issues. It's not the best drive in the world but it's a separate drive from the OS, and "E:\Recorded TV" is an excluded location in Windows Defender. Is it worth excluding any MediaPortal processes?
    • I did wonder about possible driver/card issues. I'm not the only person who seems to be having problems with TBS cards. Mine is a dual tuner TBS6982 on the most recent driver on their website, v1.0.0.6. If I re-find any posts I read before, I'll link them.
    I'm open to any explanations that may help me fix this, so I'm not discounting anything at this stage. You're the experts. ;-)

    As I've been typing, I ran the time shifting as you suggested. In the first screenshot the signal quality died within a minute and then I got the discontinuities you mentioned. Before the signal dies, the discontinuities were at zero. On the second run, it just ran and ran without issue.

    I'll re-run it on ITV HD in a minute and re-post.
     

    Attachments

    • Signal died.png
      Signal died.png
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    • Signal still going.png
      Signal still going.png
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    mm1352000

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    Thank you for your quick and detailed response.
    You're welcome. :)

    What's peculiar is the way it simply dies and does not recover as you may see with a poor signal.
    Ability to continue or recover in the face of poor signal is very much dependent on exactly what part of the stream is corrupted. Some parts of the stream are more crucial than others. The longer the poor signal conditions persist, the more likely it is for unrecoverable corruption to affect the important parts of the stream.
    I moved house in July and the problem followed with the machine to the new satellite dish unchanged.
    Ahhh, interesting. You're right - that doesn't really fit a signal problem diagnosis.

    Signal quality and strength is pretty decent as you'll see in the screenshots in a minute. Let me know what you think.
    The absolute signal strength and quality values (eg. 95, 84) exposed by tuner cards are somewhat meaningless for various reasons. Their only real use is when it comes to comparison and/or trends. For example:
    • If the numbers for channel A are lower than the numbers for channel B on the same tuner then you'll know that channel B has better signal than channel A.
    • If the numbers for channel A are lower at 7PM than they are at 8PM then you'll know that you had better signal at 8PM.
    • etc.
    So, coming back to your comment: I would say that your screenshots aren't good evidence of decent signal.

    • It is possible the hard drive is causing the issues. It's not the best drive in the world but it's a separate drive from the OS, and "E:\Recorded TV" is an excluded location in Windows Defender. Is it worth excluding any MediaPortal processes?
    • I did wonder about possible driver/card issues. I'm not the only person who seems to be having problems with TBS cards. Mine is a dual tuner TBS6982 on the most recent driver on their website, v1.0.0.6. If I re-find any posts I read before, I'll link them.
    The primary reason I discounted both of these possibilities is that you've said the problem only affects the BBC HD channels. If it were an HDD loading or driver issue I'd have expected the problem to affect all channels and/or all DVB-S2 channels.

    ...but to answer your question about exclusion of processes: yes, I'd usually recommend exclusion of MediaPortal.exe, TvService.exe and SetupTv.exe. I don't think it'll help solve this particular problem, but I've been wrong many times before. :)

    As I've been typing, I ran the time shifting as you suggested. In the first screenshot (I'll edit the post in a moment from the other machine) the signal quality died within a minute and I got the discontinuities you mentioned. On the second run, it just ran and ran without issue.
    Bingo dingo! :)
    That signal quality drop out is exactly the sort of evidence I was hoping you'd see. In my opinion that's a clear indication that the problem is signal related. I wouldn't expect high HDD load to affect the tuner's reported signal quality.

    The obvious question would be: what caused the quality drop out?
    That's a question I can't answer with any certainty. There are many possible causes including:
    • a loose cable connection
    • bad weather and/or marginal dish/LNB alignment
    • local interference (eg. microwave or DECT cordless phone operation)
    • another program (eg. WMC) commandeering (or attempting to commandeer) the tuner
     

    mikeyp

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    Whilst I'm thinking about it, ITV HD is still timeshifting fine.

    Fair enough re. the signal values. What I can say is both tuners read the same.

    I have excluded those processes in case it will make a difference.

    Right, so we're looking at the signal. This is helpful. Let's see if I can break this down further.

    Cables checked. Seem good and solid.
    Connected direct to the Samsung TV, no issues with signal are exhibited, even on BBC One HD.
    Weather is currently fair but cold. Signal quality (quantitatively) is better in the new house over the old and I don't get any breakups in picture in all but the worst of thunder storms. Weather doesn't appear to affect the behaviour.
    Dish/LNB alignment a possibility but I think this one is better than the last.
    Local interference a possibility but hard to track down, impossible if it's a neighbour. DECT phones a possibility but not on the phone when breakups occur. Wifi kit is brand new with the house move. House move also discounts specific neighbour problems.
    WMC was previously used but has been pretty thoroughly disabled. Would be good to double check this. That said, I would have thought it would affect other channels too.

    So, if I understand you right, unlike what I've seen with freeview where the picture seems to come and go with signal, freesat requires some kind of setup of the stream? What's odd is the way the signal dies. It's perfect for the working duration watching, then over the course of about 5 seconds, it'll pixellate a little, degrade further, the picture becomes completely incomprehensible as it breaks down before dying completely. It's as though the card just isn't getting on with the BBC stream and the issue is more serious than simply signal quality. Whilst investigating, I found this thread on the kodi forums with the same card, MediaPortal backend and symptoms: http://forum.kodi.tv/showthread.php?tid=221775

    I wonder if the issue is the card...

    Edit: Just time shifted BBC One HD again, died in less than 20 seconds.
     

    mm1352000

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    What I can say is both tuners read the same.
    Certainly - the two 6982 tuners will give the same readings, as would any other 6982 tuner. However different tuner products will give different readings. You can probably see this if you compare 6982 readings with readings from the Hauppauge WinTV dualHD. Different input signal - yes. However, also different scales, precision etc.

    Cables checked. Seem good and solid.
    Connected direct to the Samsung TV...
    Just to be clear - I'm talking about the cables that run from the LNB on the satellite dish to your 6982 tuners. All connections from the dish to the tuner - including splitters and switches - must be good.

    WMC was previously used but has been pretty thoroughly disabled. Would be good to double check this. That said, I would have thought it would affect other channels too.
    Yes, true. Much of what we're ruling in and out depends on the point that the problem only affects the BBC HD channels. It's important that you're certain of that fact. Any doubt opens the door for some of the other possible causes.

    So, if I understand you right, unlike what I've seen with freeview where the picture seems to come and go with signal, freesat requires some kind of setup of the stream?
    No, you've misunderstood. There's nothing specific to Freeview or Freesat. The result - pixelation, complete stop etc. - depends on how badly the signal is affected and which parts of the stream are corrupted/missing. The picture coming and going with Freeview suggests a less severe signal problem than the complete stop on the Freesat BBC HD channels.

    What's odd is the way the signal dies.
    I agree this is odd. A weather-related issue is more usually observed as a gradual degradation (eg. a drop of 5 or 10 in strength and/or quality) with some pixelation rather than a drop to 0 (and presumably a loss of signal lock) in the space of 5 seconds as you've reported.

    It's as though the card just isn't getting on with the BBC stream and the issue is more serious than simply signal quality.
    If that were the case you'd have to take it up with TBS. All I could say is that I've not seen any reports of a compatibility issue like that. As far as I'm aware, both TBS tuners and the BBC transmission are fully DVB-S/S2 compliant. Therefore I wouldn't expect a compatibility problem.

    Whilst investigating, I found this thread on the kodi forums with the same card, MediaPortal backend and symptoms...
    At first read it seems similar. However according to the second post, that problem only affected BBC 2 HD and not BBC 1 HD. That's a significant distinguishing difference. A signal problem like yours appears to be will affect all channels on the corresponding transponder:
    http://en.kingofsat.net/tp.php?tp=508
     

    mikeyp

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    Right, I have slept on it. I got to that point where I couldn't think straight.

    Yes, indeed, I have a straight path from the dish LNBs to the tuner card. No switches, splitters or anything else to complicate matters. What I did was disconnect the dish cables from the PC and connect them to the satellite inputs on the TV. BBC One HD and BBC Two HD work fine on there.

    I have ruled out WMC. It's definitely disabled. More the point, I have a second partition on the same machine with a clean install of Windows 10 1607 Pro. I installed MediaPortal 2.1 preview and got exactly the same problem with those particular BBC channels.

    This morning is clear weather and a hard frost on the ground. Not a cloud in sight, so ideal weather for satellite broadcasts.

    He is having the problem with BBC 1 and 2 HD in the first paragraph. His later paragraph states he doesn't have issues with the SD broadcasts or other HD channels. Your transponder comment has lead to an interesting observation though. If this issue is that particular transponder, then it will affect CBBC HD as well. I have not had any issues with CBeebies HD (I have a 2 year old so this channel is on a LOT), and it does appear to be on a different transponder which is unaffected. I'll test CBBC HD on the transponder.

    Edit: I can confirm CBBC HD on that transponder is affected. CBeebies HD on the other transponder works flawlessly.
     
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    mm1352000

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    Thanks for the additional information. (y)

    Yes, indeed, I have a straight path from the dish LNBs to the tuner card. No switches, splitters or anything else to complicate matters.
    So to be clear:
    1. You have two cables (one to feed each tuner) from the dish to the card, right? (If not, please clarify.)
    2. The problem happens with the same channels on both tuners at the same time, right?

    He is having the problem with BBC 1 and 2 HD in the first paragraph. His later paragraph states he doesn't have issues with the SD broadcasts or other HD channels.
    In his second post/reply he says (and I quote):
    Quick edit to this, forget what I said about BBC 1 HD, it appears to just be BBC 2 HD.

    For the moment I have no additional suggestions or theories to add.
    I'm off to bed as it's 11:30 PM here in New Zealand. I'll be online again in 9 hours or so. :)
     

    mikeyp

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    Yes, its exactly as you say. Two cables, one to each tuner on the card. Both tuners exhibit the same symptoms.

    Fair enough. I don't know to what extent he explored the problem and it wasn't followed up. The last poster in that thread seems to be suffering a similar issue also. I'll keep poking around online and see if I can find any other sufferers.

    Don't worry. Your thoughts have been immensely helpful and I'm thinking I have a faulty card. I wish I had something else to swap it out with to test the problem. I don't really want to spend another £100.

    Thank you again. Have a good night.
     

    Owlsroost

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    Have you tried the TBS card in another PC? (or in a different card slot on the motherboard).

    It might possibly be interference from something inside the PC box that just happens to be on the right frequency to affect that particular transponder reception.

    This behaviour doesn't occur on the Freeview HD tuners, but I prefer FreeSat as they broadcast in DD which my AMP works with. It won't decode AAC as broadcast on Freeview.

    For Freeview HD, I use the 'encode to DPL II' facility in LAV Audio Decoder (settings -> mixing -> matrix encoding), then stream it as PCM to the AV receiver via SPDIF (AVR then decodes it back to surround sound). Not as good as true 5.1, but better than stereo.
     

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