Luma -> Alpha with v1.18

[amindfv at mailbox.org]

On Sun, Jan 09, 2022 at 01:53:00PM +0100, Florian Echtler via gstreamer-devel wrote:
> FWIW, I once was in a similar situation and hacked together an example of
> how to build a standalone GStreamer plugin without the library build
> environment:
> 
> https://github.com/floe/gst-plugin-minimal
> 
> Maybe this can give you some hints.
> 
> Best, Florian

Thank you, this was extremely helpful! I had to make a couple tweaks which are hopefully correct:

Remove some newer pixel formats from `format_map[]`, as well as:

    -GST_ELEMENT_REGISTER_DEFINE (alpha_combine, "alphacombine",
    -    GST_RANK_NONE, GST_TYPE_ALPHA_COMBINE);
    +GST_ELEMENT_REGISTER_DEFINE (alpha_combine);

...but I'm now the proud owner of a libgstalphacombine.so!

I'm now working on integrating this with gst_element_factory_{make,create} or similar. I'll do some digging on my own before asking questions here, but of course if anyone has a working example to share I'd be very glad to read about it. :)

Thanks,
Tom