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

[Lopes Yoann]

"While discussing this, I also found that using the Angle-version on "cheaper" Windows 7 laptops with Intel GPUs, the video is just black. "

Does this happen with the OpenGL build as well?
This is not something I was aware of, you can create a bug report.
Yoann Lopes
Senior Software Engineer - Digia, Qt
Visit us on: http://qt.digia.com
________________________________
From: development-bounces+yoann.lopes=digia.com at qt-project.org [development-bounces+yoann.lopes=digia.com at qt-project.org] on behalf of Ola Røer Thorsen [ola at silentwings.no]
Sent: Monday, June 17, 2013 2:04 PM
To: <development at qt-project.org>
Subject: Re: [Development] Multimedia video playback broken in Qt 5.x for Windows WMF OpenGL version

Mitch,
thanks for the feedback! I have a Asus G74S laptop with nvidia a 560M GPU. I've created a bug report here:
https://bugreports.qt-project.org/browse/QTBUG-31800

Yoann,
thanks for the information. I'll try to use Angle instead for now, but this will become an issue once we need to use more advanced OpenGL features. I use Qt to overlay data on top of a 3D viewer application.

For the moment, the other issue I found last week is more important and is valid for both the Angle and OpenGL versions,
https://bugreports.qt-project.org/browse/QTBUG-31731

While discussing this, I also found that using the Angle-version on "cheaper" Windows 7 laptops with Intel GPUs, the video is just black. There is no apparent error messages. The video appears to be playing, but the actual texture is completely black. Same video plays back fine in Windows Media Player on the same machines. This is partially why I wanted to try the OpenGL-version to see if that was any better. Is this also a known issue, or should I create an issue on the tracker for this as well?

Best regards,
Ola Røer Thorsen

Den 2013-06-17 13:40, skrev 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>


_______________________________________________
Development mailing list
Development at qt-project.org<mailto:Development at qt-project.org>
http://lists.qt-project.org/mailman/listinfo/development


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?
_______________________________________________
Development mailing list
Development at qt-project.org<mailto:Development at qt-project.org>
http://lists.qt-project.org/mailman/listinfo/development


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/development/attachments/20130617/e0747a5a/attachment.html>