Can't watch any channels, but scan works (1 Viewer)

RobNorthcott

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    I've got a weird problem with my single-seat MP installation. Recently (a few days ago) it stopped being able to receive any channels. I assumed the dish had moved in the wind but checked it today and it's fine. Both my DVB-S tuners are able to run a channel scan, but channel preview fails with "unknown error". Same error when trying to watch from inside MP. I also get the same with the DVB-T tuner, which doesn't get a very strong signal here but usually works.

    I've tried updating the tuner drivers but that's made no difference, and updated MP to the latest release just in case.

    It's possible my tuner card has gone faulty, but it's odd that the channel scan works, and that the DVB-T tuner gives the same "unknown error".

    Logs attached - any suggestions gratefully received :)
     

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    CyberSimian

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    Recently (a few days ago) it stopped being able to receive any channels.
    From the TvService log, one error is that TV Server is unable to start graph. I don't know what that means, but it may be codec related (perhaps someone else can confirm?).

    I see that you are using Windows 10. Wasn't there a Windows 10 update recently? Possibly the update has altered a setting or disabled something that is causing this problem.

    If you are in the habit of creating drive images on a regular basis (for example, once per week), my suggestion is to restore an older drive image to see if that cures the problem. If it does cure the problem, then you need to disable Windows Update to prevent the bad update being re-installed. (I think that you will need to use some non-Microsoft software to accomplish this.)

    -- from CyberSimian in the UK
     

    RobNorthcott

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    Thanks @CyberSimian - there have been a few Windows updates recently, so possibly one of those has broken something. I'll have a check of the codecs and see if any recent update may have changed something. Thanks for the hints...

    (unfortunately I haven't made a complete system drive image of that machine for ages though)
     

    doskabouter

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    I do see some ipv6-like messages in the logfiles, could it be that somehow ipv6 is enabled?
    Either way, can you check if disabling ipv6 solves the issue?
     

    RobNorthcott

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    Disabling IPV6 didn't make any difference unfortunately. I'll try removing a few more updates next time I get a chance, unless I can find a definite cause for the problem.

    Does anybody know what "start graph" is actually trying to do? Not knowing anything about these sorts of drivers, it seems to me that if the channel scan works then the tuner hardware and driver must be working - is that true or does it need to do something fundamentally different to receive a DVB stream than to collect channel tuning info?
     

    CyberSimian

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    Does anybody know what "start graph" is actually trying to do?
    I think that when playback of a video stream is requested by the user, the system (MP or Windows or ...) creates a "graph" of different processors that specifies how the data is to be processed. It starts with the composite data stream which must be split into audio, video, subtitles, and (maybe) other stuff. So visually it looks like a flow diagram. (I don't understand why the term "graph" is used for this.)

    Scanning for and detecting channels does not involve a "graph", so that would still work OK. It is when you try to play live TV, or watch recorded TV or other video that the graph problem would arise.

    I think that the graph indicates which codecs are to be used for each component of the data. So a problem with one or more codecs on your system could result in MP being unable to create a complete graph. The codec problem could be because a required codec has been deleted, or removed from the list of available codecs, or the default codec has been changed, or something else. There is some way of viewing a list of codecs, and changing which codecs are the default ones, but I don't know how to do that (I suspect that it is a command with a horribly-obscure syntax consisting of strings of hexadecimal numbers). :(

    -- from CyberSimian in the UK
     

    RobNorthcott

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    Thanks @CyberSimian - that does tend to support my theory that the hardware and tuner driver are OK and it's "just" a codec/some other software problem. I'll keep poking around...
     

    CyberSimian

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    One other datum that might be of interest: on my system, MP will occasionally terminate and then restart immediately. It does this when I am trying to start watching video (live TV or a recording). Usually there is no problem after the MP restart. But this event occurred a couple of days ago (using MP 1.29 on 64-bit Windows 7), and on that occasion MP could not play any video after the MP restart -- it displayed a pop-up listing some stuff (I should have taken a screen shot). It was necessary to reboot the system in order to clear this problem. So it looks as though the error that MP encountered screwed-up the available codecs in some way, and the reboot was necessary to reset them.

    When the MP restart was triggered, Windows displayed something like "Graphics driver failure". I am using an old graphics card (Nvidia GT-610), which is no longer supported in the current Nvidia driver package, so I have to use an older driver package, which perhaps has some residual bugs.

    -- from CyberSimian in the UK
     

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