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

[Lopes Yoann]

Hi,

This is a known issue.

Angle and OpenGL builds use different decoding pipelines. With Angle, the plugin can do hardware decoding using DXVA, while when using pure OpenGL it is not possible and the pipeline is setup with a custom video sink (software decoding) that is known to be buggy...

If you can, use the Angle build. Not only you'll get better performance but it will also be much more stable.

The problem you are reporting should probably be fixed anyway, please create a bug report.

Yoann Lopes
Senior Software Engineer - Digia, Qt
Visit us on: http://qt.digia.com

On Jun 17, 2013, at 1:18 PM, Mitch Curtis wrote:

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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