I can play video on FB0 (video16) and overlay text using FB1 using a dedicated video player application. This works well but when I start X-Windows (system configuration GUI) the image looks like FB0 is still in YUV input mode and thus the image is stretched with the wrong colors. Also the console background is green. I don't have this problem when using video17 as the playback device but then the text overlay is not possible. Is there some way to reset the IPU? I suspect Video4linux doesn't clean up nicely.
I suspect Video4linux doesn't clean up nicely.
I'm seeing something very similar, and am coming to the same conclusion - following GStreamer playback using the imxv4l2sink element, the framebuffer that was used for video output is "stuck" as YUV.
Did you ever trace this down to a root cause?
The device in an iMX6Q. I have already solved the problem by using a different route. It wasn't clear to me how the alpha works based on the documentation and FB IOCTL examples which all set the alpha value to 0 (off). By setting the alpha to 255 FB0 is visible on top of the video played on video17 (FB1). The application is a very simple one which reads JPEGs from a file, pulls them through the VPU decoder and dumps the result into the video4linux kernel device. Writting the text is also implemented directly because that was the quickest route to take given the code I had already available from older projects.
Please provide some more details on the issue. What exactly i.MX part do you use? What device physically sits as video16? What software do you use to play video and overlay the text? Please specify.