[SOLVED] Dropped frames caused by subtitle rendering

1st Official Post

    wrxtasy edit: Solved !

    See Post #207 (click)

    Hello !

    Playing videos with subtitles enabled causing dropped frames.

    Please check the sample and Debug Log I've uploaded.

    I was using Libreelec [8.90.4] on a Minix U9 ( S912 ) but it's important to note that the bug can be reproduced on Krypton too using build 8.2.0.1 (2017-10-28) from kszaq.

    I've also reported this bug in the official Kodi forums yesturday and it's already closed with the following comments from peak3d :

    • I tested the sample movie with subtitles visible on odroid-C2.

    For this test I added the drop:0/1 log item to RenderUpdate log line.

    I played the movie 3 times (latest kodi master) without any drop, but on a 60hz monitor (no 23.9 capabable device available.

    • From debug log it seems to be kszaq's LE build wich is modified regarding AML video pipeline in many places. Because of this I suggest that you place the issue in LE forum / or directly in kszaq's git branch.


    I hope you guys can look into it as it's obvious that team Kodi won't / can't help here.

    I imagine 99,9% of the developers don't watch movies / tvshows with subtitles but I'm sure there are a whole lot of people who do so please dear developers try to fix this as it's nothing more annoying as watching something with dropped frames ^^

    Thanks

    Quote from kszaq

    It can also be reproduced on other Kodi platforms (RPi, Windows). I tried to fix it but I have no skills, sorry.

    And yet the Kodi developer wrote just recently that he couldn't reproduce it and has the opinion that the bug is specific to kszaq's git branch ?(

    Seems there is still a communication problem here. Is there anything we can do here to support you guys ???

    I can't belive I have to sell the box I've just bought as I can't watch dropped frames ;(

    Quote from avirex

    and has the opinion that the bug is specific to kszaq's git branch

    How can it be specific to my branch if I don't provide any Leia builds?

    I think that you shouldn't report Kodi bugs using non-official builds, i.e. community builds with lots out-of-tree patches. Something is considered a bug only if you can reproduce it with some kind of "official" build.

    I mentioned about dropped frames in Krypton some time ago.

    In my case they are visible only with first line of subtitles showing on the screen.

    After that the video plays smooth. The format of subtitles doesn't matter (txt, srt, sub).

    It's very easy to reproduce.

    Play any 23.976 fps movie with external subtitles and you'll see dropped frames the moment first subs appear on the screen. Sometimes it's very visible and sometimes bearly visible, even playing the same file.

    The issue is present in all Krypton builds. Leia too.

    If you want butter smooth playback use latest Jarvis build.

    Forgot to mention that dropped frames will be visible only with active Adjust display refresh rate.

    The bug is not present when Sync playback to display is enabled. So, to be precise:

    Adjust display refresh rate ON / Sync playback to display OFF - dropped frames

    Adjust display refresh rate OFF / Sync playback to display ON - no dropped frames caused by subtitles but dropped frames every now and then caused by the nature of 50/60 hz TV playing 24 fps content.

    Adjust display refresh rate ON / Sync playback to display ON - dropped frames but often less visible.

    So maybe it has something to do with refresh rate?

    Edited 4 times, last by yatoya (November 20, 2017 at 10:49 PM).

    just tried the file using 8.2.0.1 and LE9, it's a hit or miss, sometimes it stutters but sometimes not. so not sure if it's specific on that encode.

    i always watch movies with subtitles on and doesn't encounter the stutters at all. 95% of the files are 1080p scene rips with external .srt. All have the standard 23.96.

    Quote from frequenzy

    just tried the file using 8.2.0.1 and LE9, it's a hit or miss, sometimes it stutters but sometimes not. so not sure if it's specific on that encode.

    i always watch movies with subtitles on and doesn't encounter the stutters at all. 95% of the files are 1080p scene rips with external .srt. All have the standard 23.96.

    You may be not so sensitive to that problem. I assure you it's there and it's not specific to that encode I've linked.

    Sometimes it stutters but sometimes not doesn't make much sense for me.

    Quote from avirex

    You may be not so sensitive to that problem. I assure you it's there and it's not specific to that encode I've linked.

    Sometimes it stutters but sometimes not doesn't make much sense for me.

    here is the video i captured while playing your test file, there is no drops based on the codecinfo

    Code
    http://www.mediafire.com/file/kjxyb99rhxs9y94/IMG_9191.MOV

    display refresh rate ON / Subtitles Off - No suttering (1080p - 23,976 )

    display refresh rate ON / Subtitles ON - Suttering ( 1080p - 23,976 )

    Maybe it's not refresh rate issue

    Quote from Ter0

    display refresh rate ON / Subtitles Off - No suttering (1080p - 23,976 )

    display refresh rate ON / Subtitles ON - Suttering ( 1080p - 23,976 )

    Maybe it's not refresh rate issue

    True. But we can agree it stutters only in 24p mode. So, subtitles rendering process somehow affects playback.

    Well, it's a small bug. I like it too when everything works perfectly but we must remember that kszaq and other developers share with their work for free. If you don't like it use buggy Android version.

    Are you guys using any "fancy" font for your subtitles? I have been watching 23.976 clips for a long time (with subtitles of many kinds) and have not noticed any frame jumps recently. And I am very sensitive to all kind of stuttering.

    The only case when there is a frame jump is the "Avatar" sample with forced PGS subtitles.