GStreamer video window not opening (macOS) - c

Question

I am trying to run the first tutorial on GStreamer and running into some issues.
When I compile the code found here and run it, no compilation errors or warnings occur and the stream is found, but only the audio plays. When I run the executable with the GST_DEBUG environment variable set to 3, then I get the following debug output:
0:00:00.312559000 5230 0x7f8326031ad0 FIXME videodecoder gstvideodecoder.c:928:GstFlowReturn gst_video_decoder_drain_out(GstVideoDecoder *, gboolean):<vp8dec0> Sub-class should implement drain()
0:00:00.355530000 5230 0x7f8325139ed0 FIXME videodecoder gstvideodecoder.c:928:GstFlowReturn gst_video_decoder_drain_out(GstVideoDecoder *, gboolean):<vp8dec0> Sub-class should implement drain()
0:00:00.355659000 5230 0x7f8325139ed0 FIXME videodecoder gstvideodecoder.c:928:GstFlowReturn gst_video_decoder_drain_out(GstVideoDecoder *, gboolean):<vp8dec0> Sub-class should implement drain()
So it seems like there is some error either in my install of the videodecoder or the videodecoder itself, I can't say for certain.
When I try running the same media directly from the gstreamer CLI using the command
./gst-launch-1.0 -v playbin uri=https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm
I get a small OpenGL window that plays both the video and audio without any hiccups.
When I tried to install GStreamer and its plugins from brew, I ran into issues with certain plugins missing (namely certain decoders and demuxeres like vorbisdec). When I run the gst-launch tool from the brew install, I get warnings regarding the missing vorbis decoder. In this case, video plays without incident but audio does not.
Could this be an issue with the GStreamer framework pointing to the wrong plugins or directories? How can I diagnose this and/or fix it? Any help is greatly appreciated!

Answer 1

You might be running into https://gitlab.freedesktop.org/gstreamer/gst-docs/-/issues/10: on macOS you need to have a GLib main-loop running in order to display an OpenGL window. So in the tutorial you'll need to add something along the lines of this to make it work:
// Construct main-loop
GMainLoop *main_loop;
main_loop = g_main_loop_new(NULL, FALSE);
(...)
// Run main-loop
g_main_loop_run(main_loop);
(...)
// Clean-up
g_main_loop_unref(main_loop);
See tutorial 12 for an example.
As for the plugins not working with the Homebrew installation, you'll need to specify the location of the plugins manually. Depending on where Homebrew installed them and which ones you installed, it might look something like this:
export GST_PLUGIN_SYSTEM_PATH="/usr/local/opt/gst-plugins-good/lib/gstreamer-1.0/:/usr/local/opt/gst-plugins-bad/lib/gstreamer-1.0/:/usr/local/opt/gst-plugins-base/lib/gstreamer-1.0/:/usr/local/opt/gstreamer/lib/"