Duplicated video output in the same qml camera item

Question

I'm trying to figure out can be the problem of my code where I try to use a camera in an IMX.6 board. The problem is that the qml code I'm using is duplicating the output horizontally.

I'm starting the Qt application using "-platform wayland" (I have the required libraries for that). Also I'm using Gstreamer libraries.

This is the output of the camera:

Duplicated video from the camera

This is the code I used from a Qt example:

    Camera {
        id: camera
        deviceId: QtMultimedia.availableCameras[0].deviceId 
        captureMode: Camera.CaptureViewfinder
    }

    VideoOutput {
        source: camera
        width: 520
        height: 450
        x: 140
        y: 30

        orientation: 0
        focus : visible
    }

Any advise would be welcome.

Answer 1

This is not duplicated camera output. Looks like the problem with timings of camera frames (VSYNC).

New frame (VSYNC) might arrived before to render the previous frame by capture application. The view what you see is merger of two continuous frames from camera.

Measure VSYNC of the output whether it’s inline with the expected fps.

Do you the start render the frames after get the lock signal from the video decoder? Sometimes this problem might be due to rendering the unlocked video signal.