如何在QML中播放视频？

I am new to qml. I would like to know how the video is played in the qml. How the video is handled in the back-end(The classes and modules responsible for video playback). How can i add a custom player to play back video in QML? Is there any documents on this? Is there any tutorial for writing the qt-plugin for video playback.I am new to qml. I would like to know how the v