moved old gstreamer code to a new file

src/gstreamer-main.zig

@@ -0,0 +1,75 @@
+const std = @import("std");
+const gst = @cImport({ // glib-object for g_object_* functions
+    @cInclude("glib-object.h");
+    @cInclude("gst.h");
+    @cInclude("glib.h"); // and glib for other g_* functions
+});
+
+pub fn main() void {
+    // This allows me to utilize the same command line args and gstreamer
+    gst.gst_init(@ptrCast(&std.os.argv.len), @ptrCast(&std.os.argv.ptr));
+
+    const source: ?*gst.GstElement = gst.gst_element_factory_make("videotestsrc", "source");
+    const sink: ?*gst.GstElement = gst.gst_element_factory_make("autovideosink", "sink");
+
+    const pipeline: ?*gst.GstElement = gst.gst_pipeline_new("test-pipeline");
+
+    if (source == null or sink == null or pipeline == null) {
+        std.debug.panic("Not all elements could be created!", .{});
+    }
+
+    // When you look into the GST_BIN macro that zig can't compile,
+    // it really is just this pointer cast with extra steps of verification
+    const bin: *gst.GstBin = @ptrCast(pipeline);
+
+
+    // Gstreamer gives a critical warning when using gst.gst_bin_add_many, but doesn't
+    // when calling each individually
+    _ = gst.gst_bin_add(bin, source);
+    _ = gst.gst_bin_add(bin, sink);
+
+    // the failure return code is -1 I believe
+    if (gst.gst_element_link(source, sink) < 0) {
+        gst.gst_object_unref(pipeline);
+        std.debug.panic("Elements could not be linked\n", .{});
+    }
+
+    // g_int is just i32. You can 
+    gst.g_object_set(source, "pattern", @as(i16, 0));
+
+    const ret = gst.gst_element_set_state(pipeline, gst.GST_STATE_PLAYING);
+    if (ret == gst.GST_STATE_CHANGE_FAILURE) {
+        gst.gst_object_unref(pipeline);
+        std.debug.panic("Could not start pipeline", .{});
+    }
+
+    const bus: *gst.GstBus = gst.gst_element_get_bus(pipeline);
+    const msg: *gst.GstMessage = gst.gst_bus_timed_pop_filtered( // This call holds until there is a valid message
+        bus,
+        gst.GST_CLOCK_TIME_NONE,
+        gst.GST_MESSAGE_ERROR | gst.GST_MESSAGE_EOS,
+    );
+
+    if (gst.GST_MESSAGE_TYPE(msg) == gst.GST_MESSAGE_ERROR) {
+        const err: [*c][*c]gst.GError = null;
+        var debug_info: ?*gst.gchar = null;
+
+        switch (gst.GST_MESSAGE_TYPE(msg)) {
+            gst.GST_MESSAGE_ERROR => {
+                gst.gst_message_parse_error(msg, err, &debug_info);
+                std.debug.print("Error received from element {s}: {s}", .{ gst.GST_OBJECT_NAME(msg.src), err.*.*.message });
+                if (debug_info != null) { // I couldn't figure out how to do a orelse statement for this unwrap. 
+                    std.debug.print("Debugging information: {s}", .{debug_info.?});
+                }
+                gst.g_clear_error(err);
+                gst.g_free(debug_info);
+            },
+            else => {},
+        }
+        gst.gst_message_unref(msg);
+    }
+
+    gst.gst_object_unref(bus);
+    _ = gst.gst_element_set_state(pipeline, gst.GST_STATE_NULL);
+    gst.gst_object_unref(pipeline);
+}