[Xorg] Implementing "Xv" extension on DDX which don'tsupportit in hardware...

[Roland Mainz]

Eric Anholt wrote:
> > > > Is there a way to implement the "Xv" extension on hardware which doesn't
> > > > support it (for example Xnest, Xvfb etc.) ?
> > >
> > > I guess since nobody can see the display in Xvfb a "correct"
> > > implementation would be to offer Xv overlays that have no-op functions
> > > (and anyone reading back the fb - well its a hardware overlay so you
> > > dont see the data ;))
> >
> > Dumb question:
> > I cannot implement "Xv" in a way like Mesa implements GLX for Xvfb (e.g.
> > push images via XPutImage()), right ?
> >
> > Are the "Xv" overlays _required_ to leave the underlying framebuffer
> > contents intact ?
> 
> No, most XV implementations paint a color key on the underlying
> framebuffer,

Who paints the color key ? The server-side part of "Xv" ?

> so you typically don't read back the video if you do a
> screenshot, for example.

Known problem... :)
Would it be possible to implement a "generic" codepath in Xv which
renders the image using PutImage when there is no special support for Xv
in the DDX ?

> > > For Xnest there is certainly nothing preventing it providing you go off
> > > and write enough code. Xnest is an Xwindow, that means the Xv layer of
> > > the master X server is perfectly capable of handling an Xv subwindow in
> > > the Xnest window - you just have to get all the overlay offsets correct
> > > and propogate the functionality.
> >
> > What if the underlying Xserver does not support "Xv" ?
> 
> Then implement the conversion/scaling in software, or don't expose it.
> 
> One thing I've been talking with Kieth about is possibly supporting YUV
> surfaces in Render.

Uhm... we're doing some investigation whether it's possible to implement
non-RGB visuals using a "ColorSpace"-extension - having YUV- and
CYMK-visuals would be nice... :)
Maybe we should stick our heads together... is there any conference here
in europe you can visit this year ?

----

Bye,
Roland

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