mediaplayer automatically skips ahead by a few seconds

[joel08]

I'm using mediaplayer on linux to play mp4 videos and the mediaplayer uses GStreamer as backend by default. After starting the playback, it automatically skips ahead by a few seconds. This issue does not always occur, and the amount of time the video skips forward is not consistent. When using the command-line tool gst-launch-1.0 provided by GStreamer to execute the same pipeline, I do not encounter the issue of the video jumping forward. Is this problem caused by Qt?

here is the pipeline:

gst-launch-1.0 playbin3 uri=file:///path/to/video.mp4

When using mediaplayer, the source is set to the same pipeline.
Actually, I'm using qml Loader to dynamicly load the mediaplayer from another qml file which contains a mediaplayer component and the source of the mediaplayer is set with onLoaded function.

import QtQuick 2.15
import QtQuick.Controls 2.15


ApplicationWindow {
    visible: true
    width: 640
    height: 400
    Loader {
        id: playerLoader
        anchors.fill: parent
        source: "VideoPlayer.qml"
        onLoaded: {
            if (playerLoader.item) {
                playerLoader.item.source = "gst-pipeline: playbin3 uri=file:///path/to/video.mp4"
            }
        }
    }
}