[solved] Green Screen TV/TV Recording (1 Viewer)

joecrow

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    I have recently begun to experience green screens very intermittently when watching live DVBT2 HD (HEVC) TV and yesterday evening I also got it with a TV recording. On replaying the recording the green screen always occurs in the same place and is 100% reproducible, it plays quite normally for over 1 hour then the audio makes a machine gun like sound for a moment, the screen goes green, the audio plays again normally but the screen (TV window) remains green, what can be seen of the GUI/desktop desktop display is OK (see screenshot). Using the recording to reproduce the problem at will I was able to prove that the problem happens with both Madvr and EVR, latest and old (pre-2017) Nvidia drivers, a variety of different LAV audio/video settings:eek:. the only thing that changed the problem was setting DXVA2 Copy-back to DXVA2-Native which resulted in an ongoing video stutter, following the problem point, rather than the green screen and unchecking HEVC hardware acceleration in LAV where upon it played through the problem point with only a very short and minor, possible, interference glitch on the video. Not having HEVC hardware acceleration is not for me a solution as it raises my CPU usage to borderline high.
    EDIT please note the problem can usually be corrected by stopping and restarting TV/recording but sometimes an MP restart was required as screen went black on stop.
    Any other ideas/suggestions on how to fix this, Logs of a single incidence I reproduced of the problem are attached.
    green.jpg
     
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    mm1352000

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    Hello

    From your description (stutter always in same place etc.) it sounds like there may be corruption in the stream (either live TV or recording). If I'm right, my recommendation would be to try to find and eliminate the source of the corruption (eg. low signal strength/quality or high HDD load). Codecs can't work properly/perfectly if there is corruption in the stream. They may do all sorts of things - green screens, pixelation, pops/crackles, freeze, loop etc. - but they're just symptoms. Focus on the cause.

    Given that you're dealing with HEVC/h.265 - which is still so new in broadcast - I suppose there's also a possibility of a driver (DXVA) or codec bug. That's outside your control though. I suggest to try to eliminate the possibilities (signal etc.) that are within your control first.
     

    joecrow

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    Focus on the cause.
    Fully agree with that, for sure there is a momentary disturbance on the stream as can be seen when hardware HEVC accelaration is unchecked. According to the receiving details Signal Strength is 84 and Quality 100 for this channel (same or very similar for all channels I've checked) and PQ is otherwise brilliant. The recording plays for over 1 hour problem free and is also good following the problem point also that is the first time I've caught it on a recording and I do quite a bit so it really is very infrequent. HDD load, I'm not too sure, it is possible that another recording was being made at the same time, Recorded TV is stored on a regular WD Green non OS disk. As mentioned in the OP I have also seen the problem with Live TV and I think on a diffrent channel and with no recording in process but will note that for certain on next instance.
    What I am sure of is that I never saw the problem in the DVBT2 test phase (same hardware) but they changed all the frequencies when they switched fully on the 31-March, so maybe its now more prone to interference? Please note I do live in an appartment block in the city centre so mobile telephone use, radios from passing emergency vehicles etc etc could all be a factor.
    I have tested further and can confirm the same problem with MPC-HC but after copying the vid to my Desktop PC (AMD RX 460 GPU) there I see momentary pixelation at the problem point but both audio and video playback continues on without problem.;) So maybe some possibility to limit the worse effects of the problem, any thoughts on anything I could do with my Nvidia settings to make playback more robust?
     

    mm1352000

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    According to the receiving details Signal Strength is 84 and Quality 100 for this channel (same or very similar for all channels I've checked)
    The problem with those readings is that they're averages so they usually don't show "bursty" (short, quick) signal interruptions, which would be exactly the sort of signal issue that could cause what you're seeing.

    PQ is otherwise brilliant.
    That's one of the characteristics of digital TV. As long as the signal strength/quality remains above the receiving threshold, picture and audio quality should be perfect. However the signal could be only 1% above the threshold and it would still look perfect.

    ...but both audio and video playback continues on without problem. So maybe some possibility to limit the worse effects of the problem, any thoughts on anything I could do with my Nvidia settings to make playback more robust?
    Effects will be codec and GPU dependent. No surprises there for me.
    In my experience disabling DXVA can reduce symptoms. Presumably that's not practical for you due to the HEVC video decoding load.
    That's about all I can say.
    Note: as far as I'm aware the effects are completely outside MediaPortal's control.
     

    Owlsroost

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    I have tested further and can confirm the same problem with MPC-HC but after copying the vid to my Desktop PC (AMD RX 460 GPU) there I see momentary pixelation at the problem point but both audio and video playback continues on without problem.;) So maybe some possibility to limit the worse effects of the problem, any thoughts on anything I could do with my Nvidia settings to make playback more robust?
    ...Which does point to poor stream error handling in the nVidia HEVC decoder, since the AMD decoder handles it OK (unless LAV is doing different things with nVidia versus AMD DXVA). MPC-HC uses LAV decoders internally so it's no surprise that it behaves the same way.

    the only thing that changed the problem was setting DXVA2 Copy-back to DXVA2-Native which resulted in an ongoing video stutter, following the problem point, rather than the green screen
    Do you have 'Auto AV sync correction' enabled in LAV Audio settings? (this is recommended)

    In DXVA Native mode, when you get the stutter, does pausing playback for a few seconds, or skipping forward (which flushes the decoding chain and re-syncs A & V), fix the stutter?
     

    joecrow

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    ...Which does point to poor stream error handling in the nVidia HEVC decoder, since the AMD decoder handles it OK (unless LAV is doing different things with nVidia versus AMD DXVA). MPC-HC uses LAV decoders internally so it's no surprise that it behaves the same way.
    With respect to MPC-HC I have in fact set it up to use the external LAV filters (this was so I could test 3D playback with LAV 0.69 (internal LAV ver was older) so yes no surprise but it does seem to eliminate MP.[/QUOTE]

    Do you have 'Auto AV sync correction' enabled in LAV Audio settings? (this is recommended)
    Yes, also tried it without to no effect.


    In DXVA Native mode, when you get the stutter, does pausing playback for a few seconds, or skipping forward (which flushes the decoding chain and re-syncs A & V), fix the stutter?
    No tried that but it did not resync just retried DXAV2-Native again and this time got continuous stutter back and forward between just before and just after the problem point (audio continued on) and left and right buttons did not work, no OSD.
     

    mm1352000

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    No tried that but it did not resync just retried DXAV2-Native again and this time got continuous stutter back and forward between just before and just after the problem point (audio continued on) and left and right buttons did not work, no OSD.
    EVR or madVR?
    This strikes me as unusual. As Owlsroost has said, usually skipping back 5/15 seconds then skipping forward again will enable codecs to recover. I personally haven't found that pause + unpause works, but that could be codec-specific (Cyberlink).
     

    joecrow

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    EVR or madVR?
    This strikes me as unusual. As Owlsroost has said, usually skipping back 5/15 seconds then skipping forward again will enable codecs to recover.
    As of now (after trying out and changing some settings) it still always green screens with -Copy Back, audio continues to play, both Madvr and EVR.
    With -Native and EVR I get the same machine gun audio at the problem point but video freezes on a single frame and stays that way audio continues on, stepping forward/backward, pause/unpause do not work at all and OSD is not shown, other remote keys also are not working except stop which closes MP and desktop is displayed (looks like MP may have crashed behind the frozen screen).:eek: With -Native and Madvr same momentary machine gun audio while video either stays frozen for a short while, then stutters back and forward a short way or after using the forward key flip forward and freeze again, audio does respond to forward/backward, pause/unpause but OSD is not displayed and video never resyncs, pressing stop closes TV and returns to GUI.
     

    mm1352000

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    Interesting that you should say crash.
    The application event log does contain a bunch of entries like this:
    [collapse]
    "23/04/2017 15:18:41";"Windows Error Reporting";"(0)";"Information";"Fault bucket , type 0 Event Name: LiveKernelEvent Response: Not available Cab Id: 0 Problem signature: P1: 141 P2: ffffb40b1e3f74a0 P3: fffff80e4e2fe0a4 P4: 0 P5: 0 P6: 10_0_14393 P7: 0_0 P8: 256_1 P9: P10: Attached files: \\?\C:\Windows\LiveKernelReports\WATCHDOG\WATCHDOG-20170423-1518.dmp \\?\C:\Users\Media Portal\AppData\Local\Temp\WER-1850953-0.sysdata.xml These files may be available here: C:\ProgramData\Microsoft\Windows\WER\ReportQueue\Kernel_141_5c3b60a427346032f5b68888e0da5a33944b5494_00000000_04bc4c72 Analysis symbol: Rechecking for solution: 0 Report ID: 5c1d3e23-2827-11e7-b503-00243203fa01 Report Status: 4 Hashed bucket: ";"1001"
    "23/04/2017 15:18:42";"Windows Error Reporting";"(0)";"Information";"Fault bucket , type 0 Event Name: LiveKernelEvent Response: Not available Cab Id: 0 Problem signature: P1: 141 P2: ffffb40b1e3f74a0 P3: fffff80e4e2fe0a4 P4: 0 P5: 0 P6: 10_0_14393 P7: 0_0 P8: 256_1 P9: P10: Attached files: \\?\C:\Windows\LiveKernelReports\WATCHDOG\WATCHDOG-20170423-1518.dmp \\?\C:\Users\Media Portal\AppData\Local\Temp\WER-1850953-0.sysdata.xml These files may be available here: C:\ProgramData\Microsoft\Windows\WER\ReportArchive\Kernel_141_5c3b60a427346032f5b68888e0da5a33944b5494_00000000_cab_0abc4cef Analysis symbol: Rechecking for solution: 0 Report ID: 5c1d3e23-2827-11e7-b503-00243203fa01 Report Status: 2048 Hashed bucket: ";"1001"
    "23/04/2017 15:19:01";"Windows Error Reporting";"(0)";"Information";"Fault bucket , type 0 Event Name: FaultTolerantHeap Response: Not available Cab Id: 0 Problem signature: P1: MediaPortal.exe P2: 1.16.0.0 P3: 58F264EA P4: 256 P5: P6: P7: P8: P9: P10: Attached files: These files may be available here: C:\ProgramData\Microsoft\Windows\WER\ReportQueue\NonCritical_MediaPortal.exe_a06c93e2b958a317343e55663bbd47d2bf508f11_00000000_04fc985f Analysis symbol: Rechecking for solution: 0 Report ID: 69da2ffd-2827-11e7-b503-00243203fa01 Report Status: 4 Hashed bucket: ";"1001"
    "23/04/2017 15:19:01";"Windows Error Reporting";"(0)";"Information";"Fault bucket , type 0 Event Name: FaultTolerantHeap Response: Not available Cab Id: 0 Problem signature: P1: MediaPortal.exe P2: 1.16.0.0 P3: 58F264EA P4: 256 P5: P6: P7: P8: P9: P10: Attached files: These files may be available here: Analysis symbol: Rechecking for solution: 0 Report ID: 69da2ffd-2827-11e7-b503-00243203fa01 Report Status: 262144 Hashed bucket: ";"1001"
    "23/04/2017 15:19:02";"Windows Error Reporting";"(0)";"Information";"Fault bucket 129421299356, type 5 Event Name: FaultTolerantHeap Response: Not available Cab Id: 0 Problem signature: P1: MediaPortal.exe P2: 1.16.0.0 P3: 58F264EA P4: 256 P5: P6: P7: P8: P9: P10: Attached files: These files may be available here: C:\ProgramData\Microsoft\Windows\WER\ReportArchive\NonCritical_MediaPortal.exe_a06c93e2b958a317343e55663bbd47d2bf508f11_00000000_16049c28 Analysis symbol: Rechecking for solution: 0 Report ID: 69da2ffd-2827-11e7-b503-00243203fa01 Report Status: 0 Hashed bucket: 9b27c0a3310121cd0695a3afd25b4a09";"1001"[/collapse]

    I've not seen anything like that before. I'll have to do some research, but I might guess that "FaultTolerantHeap" implies that the heap (memory) is getting corrupted.
     

    joecrow

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    I've not seen anything like that before. I'll have to do some research, but I might guess that "FaultTolerantHeap" implies that the heap (memory) is getting corrupted.
    I will be very interested to know what you find out there.
    In the mean time I have re-installed the AMD RX 460 in my HTPC, I had always intended it for the HTPC but the several teething problems I had (that will teach me to buy state of the art:rolleyes:) forced me to go to Nvidia. As far as I can tell those teething problems have now been resolved, everything is looking good and the problem recording does play through the problem point with just some minor pixelation, so at least for that it seems more robust, so I will see how it performs in regular use. It also, for me, has a distinct advantage regarding 3D playback which has no setup, it just works, even with PowerDVD, something that I never managed to get running with the Nvidia.
     

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