Help: Gst.ElementFactory.Make(“rtspsrc”, “source”) Always Empty

[dejongyeong]

Hi everyone 👋

I’m running into an issue with Gst.ElementFactory.Make() and could use some guidance.

I have GStreamer (MinGW) installed, with the system PATH pointing to \bin. In my C# WPF application, I’m able to successfully bind the GStreamer version and open a stream using ParseLaunch(string pipeline).

However, when I try to create elements using Gst.ElementFactory.Make(), it always returns NULL, as if it can’t find the required DLLs. This makes me suspect that the application isn’t detecting the GStreamer plugin libraries correctly.
Is there a recommended way to resolve this so that ElementFactory.Make() works as expected, instead of relying on ParseLaunch()?

I also tried adding \lib\gstreamer-1.0 to the system PATH, but that didn’t seem to help.

Any pointers or best practices would be greatly appreciated. Thanks in advance! 🙏

[badcel]

Sorry I'm not very knowledgeable with gstreamer so some question to guide you into some helpful direction:

• Can you provide some sample code?
• Did you call gst_init?
• Can you test under Linux?
• Are there any logs in the console?
• Do you have / know some sample c code that works / should work? Are you doing the equivalent in C#?

[dejongyeong]

Hi Marcel, thanks for the discussion. Unfortunately, I do not have the opportunity to test it with Linux OS.

Below is the sample code that I currently work on in C#:

public class GstModule : IModuleInitializer
{
public string Name => "GStreamer Core";

    public void Initialize()
    {
        Gst.Module.Initialize();

        VerifyElements();
    }

    private static void VerifyElements()
    {
        var elements = new[] { "rtspsrc", "decodebin", "videoconvert", "videoscale", "capsfilter", "compositor", "textoverlay" };

        foreach (var element in elements)
        {
            var factory = Gst.ElementFactory.Find(element);
            var status = factory != null ? "Y" : "N";

            if (factory == null) throw new InvalidOperationException($"Required GStreamer plugin missing: {element}");
        }
    }
}

This class will be called when the application starts.

I do not know any C code that works.

[badcel]

How do you know your code should work then?

Are you sure you don't need to Call gst_init?

ModuleInitialize sets up GirCore. It does not set up gstreamer itself.

[dejongyeong]

Hi @badcel
I didn't realize gst_init was involved. I had thought ModuleInitialize already took care of initializing gircore and gstreamer. Thanks for pointing that out.