Luma -> Alpha with v1.18

[Florian Echtler]

On 10/01/2022 09:21, amindfv at mailbox.org wrote:
> On Sun, Jan 09, 2022 at 12:33:24PM -0800, amindfv at mailbox.org wrote:
> 
> Here's my latest, boiled down to a simple example. I hope my inexperienced attempts aren't too horrifying, or if so they're easy enough to get on the right track.
> 
> I've built the .so file, which is in the current directory. I then launch a hello world pipeline (unrelated to the new plugin), and hit an error loading the .so:
> 
>      $ GST_PLUGIN_PATH=$GST_PLUGIN_PATH:. gst-launch-1.0 videotestsrc ! autovideosink
>      
>      (gst-plugin-scanner:149635): GStreamer-WARNING **: 00:02:44.715: Failed to load plugin './libgstalphacombine.so': ./libgstalphacombine.so: undefined symbol: gst_video_info_init
>      Setting pipeline to PAUSED ...
>      Pipeline is PREROLLING ...
>      Pipeline is PREROLLED ...
>      Setting pipeline to PLAYING ...
> 
> gstalphacombine.c contains "#include <gst/video/video.h>", which in turn includes gst/video/video-info.h. In other words, gst_video_info_init "shouldn't" be undefined.

It's defined for compile time, but apparently not for link time (which is 
partially deferred until the library is actually loaded in this case).

You can check with `ldd ./libgstalphacombine.so` whether there's just a library 
path missing at load time; if this is not the case, then you would need to 
modify your compiler flags to include whatever GStreamer sub-library contains 
gst_video_info_init.

Best, Florian
-- 
SENT FROM MY DEC VT50 TERMINAL

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