[Development] Multimedia video playback broken in Qt 5.x for Windows WMF OpenGL version

Mitch Curtis mitch.curtis at digia.com
Mon Jun 17 13:18:30 CEST 2013

On 06/17/2013 08:36 AM, Ola Røer Thorsen wrote:
> Hi,
> during developing an application which amongst other things plays back
> video files using the Qt 5.1 beta version on Windows 7, I've run into a
> serious problem with the media backend.
> Basically if I try to play back some video file, use "Big buck bunny"
> for example from here, http://www.bigbuckbunny.org/index.php/download/ ,
> take the 854x480p h264 file (or any other for that matter). Use the
> CuteTime demo player from here, https://github.com/nezticle/cutetime as
> it shows the same issue that I get in my own player.
> Playback starts OK but if you let it play until 3:34, it will play in
> "fast-forward". Trying to seek before this happens will make the video
> hang. Before 3:34 there will be the occational video stutter, with this
> debug output appearing on the console:
> currentPresentTime = 102.334 and sampleTime is 102.249
> This only happens using the OpenGL build, not if you use the
> Angle-build. The issue always happens at about 3:34 into the film, also
> with my own video files. I have not been able to reproduce this using
> one of the example players that come with Qt, it seems like it is
> somehow triggered by having more than just a video item on the screen
> using Quick2 (such as a text label with the current media position).
> If any of you could please try this out as well and confirm it's not
> just on my computer, I'll file a bug report?
> I've briefly looked into the WMF backend code and found that there is
> indeed some ifdef's concerning the use of either OpenGL or Angle.
> Best regards,
> Ola Røer Thorsen
> <https://github.com/nezticle/cutetime>
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Hi Ola.

I can confirm this with the latest SDK beta on Windows 7 64-bit, so 
please create a bug report. Which video card do you have?

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