UYVY camera Preview

RiteshPanchal · wrote on 20 Aug 2016, 06:41

I am using nVidia Jetson TX1 kit. I have developed TC358748 camera driver for that which output UYVY camera data in 1080p60 FPS.

I can Preview Camera using gstreamer-1.0 pipleiine. I use nvvidconv (nvidia video converter plugin) to convert UYVY to I420 and then fives to video sink element. and its working perfectly.

Now i want to view same camera preview in QT GUI with overlays and control button.

So whats the best way to do this using Qt camera framework or using QtGstreamer?

I have tried qt camera example but it is not detecting my video0 device as camera. But if i attach USB camera its detecting and showing the preview. I think its due to i need to first convert UYVY format or configure qt camera for UYVY format. Right? is the any example code for this ?

I also tried qtgstreamer and able to preview videotestsrc to QT GUI videosurface. But if i use v4l2src with nvvidconv i got "internal data flow error" I dont know why.? I can use whole pipeline but in this case i can't preview in QT gui videosurface. i can open separate windows.

Suggest some solution.

SGaist · wrote on 20 Aug 2016, 22:06

Hi and welcome to devnet,

Which version of Qt are you using ? IIRC with 5.8 there should be support for uyvy when using QML

RiteshPanchal · wrote on 23 Aug 2016, 06:11

Hello,
Thanks for the reply.

I am using Qt 5.2.1. which is installed by using apt-get install ubuntu-sdk.
In release note of 5.8 it stated that "VideoOutput (QML) now supports rendering YUV 4:2:2 (YUYV, UYVY) video frames." I think that means i can play UYVY video without any conversion.

As i am new to QT. I don't know much about Qt Multimedia framework. But can this be useful to UYVY v4l2 frame from camera? And if yes can you suggest any code snippet or example for that?

RiteshPanchal · wrote on 23 Aug 2016, 06:34

And what you recommend for my application? use Qt Multimedia framework or Qt gstreamer?

SGaist · wrote on 23 Aug 2016, 06:50

The first thing I'd try is to test with the QML camera example from Qt 5.8.

RiteshPanchal · wrote on 23 Aug 2016, 10:43

First of all how to download qt 5.8?
I am getting only 5.7 from the website. i have installed on my linux PC.
But for nvidia TX1 i have to compile the source. right?

Currently i can able to preview My camera output in qml videosurface via following code.
But i am getting Reddish preview. But if i use autovideosink instead of qml videosurface preview shows with right color.
Also if i replaced v4l2src by videotestsrc same reddish preview is coming with videosurface.

So how to get correct color preview with qml viedosurface.?


            VideoItem {
                id: video

                width: 1920
                height:1080
                surface: videoSurface1 //bound on the context from main()
            }

    // Create gstreamer elements
    m_pipeline      = QGst::Pipeline::create("Video Player + Snapshots pipelin");
    m_source        = QGst::ElementFactory::make("v4l2src", "videotestsrc");
    m_filter        = QGst::ElementFactory::make("capsfilter",	"capsfilter");
    m_convert       = QGst::ElementFactory::make("videoconvert","videoconvert");
    m_filter1       = QGst::ElementFactory::make("capsfilter",	"capsfilter1");
    //m_videoSink       = QGst::ElementFactory::make("autovideosink",	"sink");

    m_filter->setProperty("caps", QGst::Caps::fromString("video/x-raw, width=1920, height=1080, format=UYVY, framerate=60/1"));
    m_filter1->setProperty("caps", QGst::Caps::fromString("video/x-raw, width=1920, height=1080, format=I420, framerate=60/1"));

    m_pipeline->setProperty("video-sink", m_videoSink);

    if (!m_pipeline || !m_source || !m_videoSink) {
        return;
    }

    // Add elements to pipeline
    m_pipeline->add(m_source);
    m_pipeline->add(m_filter);
    m_pipeline->add(m_convert);
    m_pipeline->add(m_filter1);
    m_pipeline->add(m_videoSink);

    // Link elements
    m_source->link(m_filter);
    m_filter->link(m_convert);
    m_convert->link(m_filter1);
    m_filter1->link(m_videoSink);

SGaist · wrote on 23 Aug 2016, 20:00

You'll have to build it yourself from git. 5.8 is currently being prepared.

Are you sure you're having a uyvy input and not a yuyv ?

RiteshPanchal · wrote on 24 Aug 2016, 05:38

Ok. I will build 5.8.

And I am sure its UYVY. Because if i use any other videosink or filesink or udpsink i am getting proper color frames.

RiteshPanchal · wrote on 15 Sept 2016, 06:57

I have successfully build QT 5.8.0 on nVidia TX1 board.
But with QML video surface sink element still getting Reddish preview.
https://drive.google.com/open?id=0B8d7zQv-G71oM1JONzlpR2t1OWc

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?