QT 5.8.0 VideoOutput (QML) YUV 4:2:2 (YUYV, UYVY) video rendering

RiteshPanchal · wrote on 15 Sept 2016, 09:27

In Qt 5.8.0 Release note, https://wiki.qt.io/New_Features_in_Qt_5.8 ,

Qt Multimedia
-VideoOutput (QML) now supports rendering YUV 4:2:2 (YUYV, UYVY) video frames.

So how to test this? Is there any example code for this?
is this for UYVY video only or Camera UYVY output can also be displayed?

SGaist · wrote on 15 Sept 2016, 21:45

Hi,

It's been written using a camera as input and the OS multimedia framework provided YUV4:2:2 frames.

RiteshPanchal · wrote on 16 Sept 2016, 05:01

I also tried 5.8.0 QT C++ camera example.
but for this example camera preview seen for 1-2 sec and then ubuntu hangs. And also the preview appear with wrong color conversion format.

So i tried minimal camera example.
https://drive.google.com/open?id=0B8d7zQv-G71odXN6ZTkxRTRuOGM
But when i start camera following error comes
Unable to open the camera "" for read to query the parameter info: "No such file or directory"

So how can i preview UYVY camera preview in this example?

SGaist · wrote on 16 Sept 2016, 07:07

If the whole OS hangs it would rather be a driver problem.

RiteshPanchal · wrote on 16 Sept 2016, 07:16

Can you state whats wrong in the driver?
The Driver works with Gstreamer.

SGaist · wrote on 16 Sept 2016, 07:31

Do you mean that if you use gstreamer directly everything works but if you start a Qt application your whole computer freezes ? ("ubuntu hangs" in your last post)

RiteshPanchal · wrote on 16 Sept 2016, 08:27

Ya if i use gstreamer pipeline directly or use qt-gstreamer camera preview works with gstreamer videosink elements.
But as now want to preview camera in QT / QML window, i am using 5.8.0 camera example. And ubuntu hangs when i start this example.

I think i need to modify this example to be able to preview UYVY camera output.

SGaist · wrote on 16 Sept 2016, 08:51

IIRC QtGstreamer also provides a QML element that you can use so if you already have it running with it then I'd just use it directly.

RiteshPanchal · wrote on 16 Sept 2016, 08:57

I have already tried that and i am getting Reddish preview for UYVY to I420 conversion. I already posted this problem in other posts.
https://forum.qt.io/topic/70414/uyvy-camera-preview
https://forum.qt.io/topic/71056/gstreamer-videosink-in-qml
https://forum.qt.io/topic/70704/qtquick-videoitem-qtgstreamer-preview-color-problem

In one of the post you told me to use 5.8.0 which has UYVY support. So Now i had that version so i asked how to evaluate this?

And can i play UYVY raw video on QML?