QtAV: Qt Quick items display wrong textures

Now i’m developing rendering yuv frames with opengl for qml. Video frames can display correctly. But other items display wrong contents. Text item becomes white rectangles. Image item displays a part of video frame, the color is gray. If I render rgb frames instead yuv frames, all works fine. Now i have no ideas. What could be the reason? code is here: https://github.com/wang-bin/QtAV you can try yourself. in “examples/QMLPlayer/qml/QMLPlayer/main.qml”, add a line opengl: true in “VideoOutput” item. this is the result if rendering yuv with opengl is used the buttons should be