Audio/Video Sync Problem in Live TV

Discussion in 'General Support' started by sail323, September 25, 2011.

  1. sail323

    sail323 Portal Member

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    After watching live TV for several minutes, video will stutter then slow down while audio goes on interrupted. The video will lag audio by several seconds and not recover until I stop and restart MediaPortal. This happens with all versions of MediaPortal (1.1.0 through 1.2.0).

    I also use NextPVR, WatchHDTV and WinTV 7 but this never happens with these apps.

    Help!



    XP, SP3
    WinTV HVR-950Q w/ latest drivers
    DVB-Fix installed
     
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  3. Spooky
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    Spooky MP Donator

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    It seems you are using the default MPC codecs. Have you tried unlocked SAF6 for instance, with PowerDVD 11 configured as the video codec (MPEG2 and H.264) and LAV as the audio codec?

    Also before any more specific help can be given, you should fill out your systemspecs.
     
  4. sail323

    sail323 Portal Member

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    The only other codecs I have are the ones provided by Hauppauge.

    Video=MainConcept (HCW) MPEG-2 Video Decoder
    Audio=Hauppauge AC3 Decoder

    I've tried the video codec and get the same results. I'm not able to select the audio codec in MediaPortal even though it is registered and selectable in other apps.
     
  5. mm1352000
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    Hi sail323

    Looks to me like your signal quality is not so good. Please try to enable "don't drop discontinued packets in TsReader" in MediaPortal configuration as per the details -->here<--.

    mm

    [Edit: also double check that the folder that you're using for timeshifting is excluded from virus checking - issues have been seen before where the virus scanner made it look like there were signal problems but actually it was just slowing down the hard drive so much that it created continuity problems...]
     
  6. sail323

    sail323 Portal Member

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    mm1352000,

    Enabled it and got same result.

    I just noticed the following in the tsreader log;

    25-09-2011 18:19:27.078 [c8c]Compensation : ( Rnd : 0 mS ) Audio pts greatly ahead Video pts . Add 0.624 sec of extra video comp to start now !...( real time TV )
    25-09-2011 18:19:27.093 [c8c]Elapsed time from pause to Audio/Video ( total zapping time ) : 13181843 mS
    25-09-2011 18:19:27.109 [c8c]aud:Compensation:-0.065, Clock on start 0.172 m_rtStart:0
    25-09-2011 18:19:27.125 [c8c]aud:set discontinuity
    25-09-2011 18:19:27.140 [c8c]Aud/Ref : 0.115, Late Compensated = 0.180 ( -0.039 A/V buffers=07/03), Clk : 0.219000, State 2
    25-09-2011 18:19:27.156 [c8c]Aud/Ref : 0.147, Late Compensated = 0.212 ( -0.023 A/V buffers=16/26), Clk : 0.235000, State 2
    25-09-2011 18:19:27.171 [c38]vid:set discontinuity
    25-09-2011 18:19:27.187 [c38]Vid/Ref : 0.764, Late I-frame(02), Compensated = 0.829 ( 0.563 A/V

    Hope this helps.
     
  7. mm1352000
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    Hi again

    Check my previous post edit and ignore TsReader as that is not the cause of the problem. The source of the problem is "upstream" so to speak - either in the signal quality from your aerial or cable input, or disruption to TV Server's ability to write and read the timeshifting file from the hard drive. As I previously said, check your virus scanner (AVG, MSE, Comodo etc.) settings, and if you have a second HDD you could also try moving the timeshifting files to a different location by changing the settings described -->here<--.

    mm
     
  8. sail323

    sail323 Portal Member

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    mm

    I disabled my virus program and tried MP again and the problem still occurs. I don't have another drive to direct the ts file to, but I do have 127GB free on the current drive. Will modifying the ts parameters help?

    You're right about signal quality, it is a little weak. When I watch live TV using another app {NextPVR or WinTV 7), the video and audio will stutter or drop out for a second or two, but will always recover and come back in sync.
     
  9. mm1352000
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    Hi again

    You can't modify the TS parameters - they're set by the broadcaster. You can only modify where the TS files are stored, and if you only have one HDD then it won't make much difference.

    If you truly have a problem with signal quality then honestly the very best thing to do is to get a professional to come in and take a look.

    Different software reacts to signal corruption differently. In my opinion the best thing you can do with MediaPortal is experiment with that TsReader option that I mentioned and use codecs that are a little more resilient to signal corruption than others. The best codecs for this that I'm aware of are the FFDShow ones. Other people may well have different opinions...

    mm
     
  10. Spooky
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    But ffdshow causes desyncs even without a bad signal (didn't you work on this problem for a short time?).

    As I said in my first post, my advice would be to try the PDVD11 codec with the LAV audio codec for LiveTV.
     
  11. mm1352000
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    Not that I'm aware of. I have trouble with FFDShow when switching between different resolutions with h.264 video, and I've used Tony's (Owlsroost) patch for that...

    I find that at least PDVD10 is great at most things, but not this. Maybe PDVD11 is better...
     
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