On Tue, Aug 10, 2021 at 05:57:31PM +0100, John Cox wrote:
Hi all
I am on a Raspberry Pi, I want to display fullscreen video and have a couple of overlay planes to display controls / subtitles etc. The h/w can certainly do this. I need to be able to do this from a starting point where X is running.
I can successfully find X's output & crtc and grab that using xcb_randr_create_lease and use that handle to display video. So far so good. But I also want to have overlay planes for subtitles etc. The handle I've got from the lease only seems to have a PRIMARY & a CURSOR plane attached so I can't get anything there.
I think X just gives you a legacy lease for the crtc, and the kernel automatically adds the primary plane and cursor plane (if they exist) to that lease. Unless X is patched to enable plane support and add those all explicitly to the lease I don't think there's a way for that.
For wayland this is still in the works, so might be good if you check there that your use-case is properly supported. Protocol MR is here:
https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/67
How should I be going about getting some more planes to use for overlays? Pointers to documentation / examples gratefully received - so far my google-foo has failed to find anything that works.
I'm sorry if this is the wrong place to ask, but if there is a better place please say and I'll go there.
Many thanks
John Cox