[vlc-devel] Chroma-key plugin for VLC as class broadcast client

jpd at m2x.nl jpd at m2x.nl
Mon May 4 15:13:15 CEST 2009

On Mon, May 4, 2009 14:52, R\xc3\xa9mi Denis-Courmont wrote:
> Composite, Render extensions and WM support can trivially be auto-detected.
> I don't see a problem here. We can also fallback to Shape, i.e. 1-bit alpha
> channel, if backward compatibility is deemed worth the implementation
> effort.

That will likely depend on how the implementation is done. It might end
up being relatively trivial.

>> Since the X11 core protocol has no alpha support,
> Not sure what you mean here. My X.Org server has a 32-bits visual
> (accordding to xdpyinfo). I think it's ARGB. Unfortunately, I never
> figured out how to use it.

That would be because selecting visuals with alpha channels needs to be
done through XRender, says eg [1]. (Better references welcome.)

>> it takes an XRender-aware WM and that likely implies compositing,
>> which breaks XVideo too, so I don't think it's worth worrying about
>> that.
> Not worth worrying?

In the sense that it's not likely possible to make XVideo alpha work
anyway (unless perhaps through shape), and it very likely won't work
with compositing active.

In the sense that vlc is setup to do the wrong thing by default for
this situation, well, I wasn't talking about that. One solution might
be to make chroma key alter the output module priorities (if that is
possible), but I'm not sure that having to use a manual override when
choosing chroma key is that much of an issue, _yet_.

[1] http://ktown.kde.org/~fredrik/composite_howto.html

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