Question

I am developing Qt application for a embedded linux/MIPS device. So far managed to execute my Qt application on the device. Now I need to create overlays on top of video.
Hardware provides four overlays windows and does not support OpenGL.

Tried so far:

1. Tried creating QStackedLayout and QGraphicsView for creating overlays on top of video. But overlay appears black, though widgets on overlay responds to user click.
2. Tried to access multiple framebuffers directly. I am able to access /dev/fb0 but not /dev/fb1, 2, 3.
3. Tried creating a simple Qt application with a dialog and a push button on it. I tried executing it on embedded device using this command ./<appname> -display directfb:/dev/fb1:2. But it fails to open /dev/fb1.

Questions:

• How can I use the overlay windows provided by the LCD controller?
• Is it possible to use directfb plugin provided by QT and take advantage of its OpenGL support?
• Do I have to explicitly map /dev/fb1 to user space to be able to use it?

Need urgent help regarding this.

Answer 1

Finally got this working. I could find the interface using which I could access the framebuffers.

• Then using -display switch I directed output of Qt app to framebuffer
  meant for overlay window. The exact command used was ./app-name -display Linuxfb:/dev/fb2:enable=1.
• Also enabled the alpha mode of the framebuffer /dev/fb2 which showed
  through the video playing below.