feat: Restructure the gst parent<->child relations

gst/src/plugins/app/appsink.rs

@@ -1,19 +1,8 @@
 use crate::priv_prelude::*;
 
-#[derive(Debug, Clone)]
-pub struct AppSink {
-    inner: gstreamer::Element,
-}
-
-impl IsElement for AppSink {
-    fn as_element(&self) -> &Element {
-        unsafe { core::mem::transmute(&self.inner) }
-    }
-
-    fn into_element(self) -> Element {
-        Element { inner: self.inner }
-    }
-}
+wrap_gst!(AppSink, gstreamer::Element);
+parent_child!(Pipeline, AppSink, downcast); // since AppSink is an Element internaly 
+parent_child!(Element, AppSink);
 
 impl Sink for AppSink {}
 
@@ -136,28 +125,8 @@ fn test_appsink() {
         .expect("Link videoconvert to appsink");
 
     let playbin3 = playbin3.with_video_sink(&video_sink);
+    playbin3.play().expect("Play video");
     let bus = playbin3.bus().unwrap();
-    // playbin3.play().expect("Play playbin3");
-
-    std::thread::spawn({
-        let playbin3 = playbin3.clone();
-        move || {
-            loop {
-                std::thread::sleep(std::time::Duration::from_secs(5));
-                playbin3.play();
-                playbin3.wait_non_null_sync();
-                let sample = appsink
-                    .try_pull_sample(core::time::Duration::from_secs(5))
-                    .expect("Pull sample from appsink")
-                    .expect("No sample received from appsink");
-
-                dbg!(sample.caps());
-
-                playbin3.play();
-                tracing::info!("Played");
-            }
-        }
-    });
     for msg in bus.iter_timed(None) {
         match msg.view() {
             gstreamer::MessageView::Eos(..) => {