QVideoProbe causes the video to rotate 180 degrees with MinGW.



  • Hello, everyone.
    The problem is described in header. It occurs with video near 3 GB size and more (also, presumably, only .mkv format. I tested .mp4 which 3.81 GB and it's fine.). If I comment probe->setMedia() line it's ok. If I build programms with MSVS 2017 compiler it's also ok. Same thing with Qt examples, like videoplayer, videographiscItem. I suppose it's a rather MinGW bug , but any help will be appreciated, thanks.
    My config:
    Qt 5.9.2
    MinGW 5.3.0
    Windows 7 SP1


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Does it only happen with big video files ?



  • Hi. Yes, as I mentioned before, it occurs only for files about 3 GB size. For example with 2,93 GB file the problem appears, but 2,18 GB is ok. Both files are .mkv. I have only one .mp4 file what big enough (3,81 GB) and it's fine. Also I test one .ts file for 2,41 GB and it's ok too. All files have different resolutions, most of them HD or FULL HD but some of them have non standart resolution (1280x544 for example).


  • Lifetime Qt Champion

    Any videos of that size or it is a particular file ?
    Do you have any special codecs installed ?



  • Any video in .mkv about 3 GB and more. It likely doesn't affect .mp4 and .ts files, but i'm not sure. I have only one .mp4 and .ts files of the corresponding size. It's not enough to be sure.
    And yes, I have K-Lite Mega Codec Pack 10.6.5 installed.


  • Lifetime Qt Champion

    Pretty unusual...

    Might be a silly question but does these files trigger bugs in e.g. VLC or other media players ?



  • No, it doesn't. All files are played normal. More of that as I mentioned in the first post the problem disappears with MSVS compiler. Anyone can easy reproduce this problem. All you need is the last Qt SDK with MinGW and standard "Media Player Example". It uses QVideoProbe and if there is a bug you will see it.



  • And finally i got the solution. The problem was in outdated version of K-lite codecs. I installed latest version of K-Lite Mega Codec Pack 13.6.5 and videos play as they should. It's still very strange because videos have played well in VS build and any video player (e.g. Media Player classic, Windows Media and VLC of course).
    And of course big thanks @SGaist for help.


  • Lifetime Qt Champion

    IIRC, the two builds are not using the same backend.



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