On Tue, May 28, 2024 at 03:53:23PM +0000, Hoosier, Matt wrote: > Hi Marius, Hi, > > Okay, I guess that answers the bit about needing to screen-scrape to get > content into Pipewire now. > > But I'm still a little unclear about a couple things, if I were to try to > build on this PW backend as a starting point: > > First, it looks to me like when you use the PW backend to Weston, that > becomes your display. That is, rendering directly targets it. I was > hoping for a way to get it to broadcast the very same framebuffer(s) > that are getting scanned out for the current frame by the DRM > backend. With https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/341 the PipeWire output can mirror out the native DRM one. It aims at having a way to configure VNC, RDP and PipeWire to screen-share the output. > > Second, I'm don't see the path to getting this to leverage the > DRM_MODE_CONNECTOR_WRITEBACK hardware (like the weston_screen_recorder > does). I think that any layering would be forced to > be offloaded to the GPU ahead of time. Maybe I missed some implication > of what you were pointing out here? No sorry, I haven't really implied that, just pointed that out there's some work for PipeWire gaining dmabuf.
Screen-sharing an output is done with multiple backends, and configuring Weston front-end is it with https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/341. > > > -----Original Message----- > > From: Marius Vlad <marius.v...@collabora.com> > > Sent: Saturday, May 25, 2024 6:12 AM > > To: Hoosier, Matt <matt.hoos...@garmin.com> > > Cc: wayland-devel@lists.freedesktop.org > > Subject: Re: Full-motion zero-copy screen capture in Weston > > > > On Fri, May 24, 2024 at 09:43:58PM +0000, Hoosier, Matt wrote: > > > Hi, > > > > > > I'm interested in finding or contributing some mechanism to get sort of > > > the > > same effect as a cross between: > > > > > > > > > * > > > weston_output_capture's support for using the > > > DRM_MODE_CONNECTOR_WRITEBACK connectors, and > > > > > > * > > > the streamed orientation of weston_screen_recorder, and > > > > > > * > > > no forced reliance on the GPU to pre-blend the 2D scene – whatever > > > plane blending would otherwise have occurred must still occur when the > > > screen recording mechanism is active > > > > > > The desktop environments' compositors implement the XDG screencast > > portal. If I read things correctly, that one deposits the stream of dmabuf > > frame > > fds into the Pipewire stream indicated by the user invoking the D-Bus > > Screencast API. > > > > > > That doesn't really seem like a starter for doing this in Weston. > > > There was conversation back in 2019 about trying to add zero-copy > > > dmabuf support in Weston's own Pipewire integration, but I think that > > > didn't happen? > > https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1366 > > > > > > Alternately, I see that the remoting plugin on today's main branch > > > supports > > GStreamer dmabuf allocators. Does this mean that I could build something > > using a virtual weston_output in the drm-backend? > > > > > > Cheers, > > > Matt
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