[SOLVED] Dropped frames caused by subtitle rendering

  • Hi Pinki, this is the exact same issue i'm having, a stutter in panning scenes at the moment (or just before) the subitle appears. Good thing you uploaded a YouTube video, that's probably better then explaining it in text.

    Also, I'm not using the adjustments in the attr, nr2_en and bypass_all files you mentioned (using the echo commands). My player/video settings are the same though.

  • @MichelLoyen


    It should not matter but did you try set different refresh rate in System settings -> Display? By default it is 60 Hz for my setup. I've changed it to 50 Hz.

    I tried it just to be sure but it makes no difference (i also tried 24 and 23.98 rates). Afaik when using the 'adjust refresh rate on start/stop' option, it does not matter what the refresh rate is of the Kodi interface as it will change according to the content which is being played (hence the option).

  • No, there is no chance to fix it in every special case.

    I´m lucky - my hardware has no issue

    I can assure you this is not hardware related and your box does have this issue. You just don't see it :)

    I'm sorry but that's the truth. Most users are happy they can use LibreELEC and they don't see any stuttering because this is not relevant to them.

    Users with more sensitive eye, you just have to accept it.

  • How is it "hardware issue" when it does not exist without hw acceleration? Looks more like a video driver issue to me.

    Hardware issue based on hardware acceleration and TV panel(hardware) - no LE developer is able to write a new amlogic hardware decoding driver until yet

  • Its possible to display subtitles without stuttering (playerdebug overlay)

    Maybe someone can add "invisible overlay" like playerdebug as workaround to fix this?

  • I`ve found interesting thing. Video stutters only in some movies, whats the difference between them?

    It looks like the problem is only with UTF8 subtitles internal/external srt? with internal PGS its OK. tested with 8 movies.

    Example of stutering subtitle in attachment

    I converted srt file from attachment to PGS (.sup) with GOSUP and then used MKVToolNix to merge PGS subtitles with mkv and now its working without stuttering!


    Text #2

    ID : 5

    Format : UTF-8

    Codec ID : S_TEXT/UTF8

    Codec ID/Info : UTF-8 Plain Text

    Duration : 2 h 1 min

    Bit rate : 33 b/s

    Count of elements : 1008

    Stream size : 29.5 KiB (0%)

    Title : Forced

    Language : Polish

    Default : Yes

    Forced : Yes

    No stuttering:

    Text #18

    ID : 38

    Format : PGS

    Muxing mode : zlib

    Codec ID : S_HDMV/PGS

    Codec ID/Info : Picture based subtitle format used on BDs/HD-DVDs

    Duration : 2 h 6 min

    Bit rate : 23.8 kb/s

    Count of elements : 2970

    Stream size : 21.6 MiB (0%)

    Title : Polish-PGS

    Language : Polish

    Default : No

    Forced : No

  • Thx. for the sample Pinki

    I can now clearly seen video frame upsets happening about every 1 second with the external subtitles when played on the U9 (S912) using Hardware video decoding.

    However my S905 ODROID C2 does not have any problems whatsoever nor does a MECOOL S905X box, both running LE 8.2.x and using HW decoding.

    It appears only S912's that are using the Hybrid Android/Linux GPU drivers are having such subtitle, video frame upset issues.
    Subtitle rendering is a GPU function.

    We really need better optimised S912 Linux GPU video drivers to fix this LE S912 problem.

    EDIT - good news S912 owners !

    I've updated the kszaq modded Hybrid GPU drivers for the S912 and added an important VSync Hardkernel ODROID C2 patch:

    [3.14] Fix vsync for Mali r6p1 and later by kszaq · Pull Request #94 · LibreELEC/linux-amlogic · GitHub

    I see no S912 Subtitle / video frame problems now playing the above test clip when using this LE 8.2.4 Kodi Krypton release:


    The Kodi user interface seems snappier now as well. :thumbup:


  • I don't really use .srt subs a lot beside for some TV shows, and use PGS for movies mainly. I do however experience this issue when using Plex for Kodi addon. It might be because the way it has a different OSD overlay over Kodi, so most my media stutter every second (no dropped frames though in codecinfo) no matter if I use subtitles or not.

    This issue has caused me to use PlexKodiConnect instead, which does not experience this issue with the same files on the same device.

    This issue has only seemed to happen on my Minix U9 and not any other Kodi running device (Sony Android TV, Windows).

    using wrxtasy build finally fixed this issue for me. Thanks a lot.