Unsolved raspberry 3b+ 64bit os run qml demo code failed

[lxy12345]

Hi all:
I made a raspberry 3b+ os by Yocto and this os works well. Today,I try the qml demo code which called "declarative-camera" but it can not work. The error is "ice(): no service found for - "org.qt-project.qt.mediaplayer"".

I have google and someone said that I should install gstreamer? There is nothing about gstreamer or libgstreamer in my OS.(I have used the cmd "find / -name libgstreamer* " but nothing appeared).

The qmake version on my os is 3.1
Qt version is 5.15.0

By the way, the demo "declarative-camera" can run perfectly on my virtual machine which env is ubuntu 16.04