How can I set subtitle on QML MediaPlayer?

Subtitle support added to Qt6 Multimedia and we can show a subtitle on MediaPlayer very simple. But I can't use this feature in QML, setSubtitleText seems not find in QML or at least not callable.

MediaPlayer {
    id: mediaPlayer

    Button{
    onClicked: {
        mediaPlayer.videoOutput.videoSink.setSubtitleText("I'm a subtitle!")
}
}

console.log(mediaPlayer.videoOutput.videoSink)

QVideoSink(0x203f364a8b0)

mediaPlayer.videoOutput.videoSink.setSubtitleText

undefined

mediaPlayer.videoOutput.videoSink.setSubtitleText("some text")

TypeError: Property 'setSubtitleText' of object QVideoSink(0x203f364a8b0) is not a function