feat: Modify gst crate to add lot of more granularity

gst/src/caps.rs

@@ -51,3 +51,12 @@ impl CapsBuilder {
         }
     }
 }
+
+impl Caps {
+    pub fn format(&self) -> Option<&str> {
+        use gstreamer::prelude::*;
+        self.inner
+            .structure(0)
+            .and_then(|s| s.get::<&str>("format").ok())
+    }
+}