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.
Bother. So near and yet so far. Thanks for the info.
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
In overall protocol terms that doesn't seem so different from what X does and I am far too inexperienced in Wayland / DRM to understand the subtleties. That MR seems to be done so is probably an inappropriate place to ask - where would you recommend as an appropriate forum?
Many thanks
John Cox
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