QML: audio plays correctly but the video doesn't

[Nekk]

Hi all.
I'm working on a embedded Yocto OpenSTLinux project. I'm developing a QT/QML application in witch I have to play videos and audios. Using the following line command

gst-launch-1.0 playbin uri=file:///home/root/media/video_test.mp4 video-sink="waylandsink sync=false"

the video and audio work correctly. Instead, using QML, for example this

Item {

    id: idVideo

    visible: true

    width: 1024
    height: 600

    Video {
        id: videoExample
        anchors.fill: parent
        source: "file:///home/root/media/video_test.mp4"
        autoPlay: true
    
        focus: true
    }
}

or this

Item {

    id: idVideo

    visible: true

    width: 1024
    height: 600

    MediaPlayer {
        id: mdpExample
        source: "file:///home/root/media/video_test.mp4"
        autoPlay: true
    }
    
    
    VideoOutput {
        id: videoExample
        anchors.fill: parent
        source: mdpExample
    }
}

the audio plays correctly but the video does not. The display doesn't show any image (it is black). Can someone give me a suggestion to solve the problem?

Many thanks

[kluszon]

@Nekk I meet the same situation on Yocto Kirkstone for iMX8.