playback: Handle sources with dynamic pads and pads already present

In case we already have a pad but more might be added later we were
ignoring the new pads added later, we should track the element
new pads and expose them as they are added.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1120>

gst/playback/gsturisourcebin.c

@@ -1630,6 +1630,8 @@ static gboolean
 analyse_source (GstURISourceBin * urisrc, gboolean * is_raw,
     gboolean * have_out, gboolean * is_dynamic, gboolean use_queue)
 {
+  GstElementClass *elemclass;
+  GList *walk;
   GstIterator *pads_iter;
   gboolean done = FALSE;
   gboolean res = TRUE;
@@ -1701,14 +1703,9 @@ analyse_source (GstURISourceBin * urisrc, gboolean * is_raw,
   gst_iterator_free (pads_iter);
   gst_caps_unref (rawcaps);
 
-  if (!*have_out) {
+  /* check for padtemplates that list SOMETIMES pads to check
-    GstElementClass *elemclass;
+   * check if it is dynamic. */
-    GList *walk;
-
-    /* element has no output pads, check for padtemplates that list SOMETIMES
-     * pads. */
   elemclass = GST_ELEMENT_GET_CLASS (urisrc->source);
-
   walk = gst_element_class_get_pad_template_list (elemclass);
   while (walk != NULL) {
     GstPadTemplate *templ;
@@ -1721,7 +1718,6 @@ analyse_source (GstURISourceBin * urisrc, gboolean * is_raw,
     }
     walk = g_list_next (walk);
   }
-  }
 
   return res;
 no_slot:
@@ -2164,25 +2160,32 @@ setup_source (GstURISourceBin * urisrc)
           urisrc->need_queue && urisrc->use_buffering))
     goto invalid_source;
 
+  if (!is_dynamic) {
     if (is_raw) {
       GST_DEBUG_OBJECT (urisrc, "Source provides all raw data");
       /* source provides raw data, we added the pads and we can now signal a
        * no_more pads because we are done. */
       gst_element_no_more_pads (GST_ELEMENT_CAST (urisrc));
       return TRUE;
-  }
+    } else if (!have_out) {
-  if (!have_out && !is_dynamic) {
       GST_DEBUG_OBJECT (urisrc, "Source has no output pads");
+
       return TRUE;
     }
-  if (is_dynamic) {
+  } else {
     GST_DEBUG_OBJECT (urisrc, "Source has dynamic output pads");
     /* connect a handler for the new-pad signal */
     urisrc->src_np_sig_id =
         g_signal_connect (urisrc->source, "pad-added",
         G_CALLBACK (source_new_pad), urisrc);
-  } else {
+  }
-    if (urisrc->is_stream) {
+
+  if (is_raw) {
+    GST_DEBUG_OBJECT (urisrc,
+        "Got raw srcpads on a dynamic source, using them as is.");
+
+    return TRUE;
+  } else if (urisrc->is_stream) {
     GST_DEBUG_OBJECT (urisrc, "Setting up streaming");
     /* do the stream things here */
     if (!setup_typefind (urisrc, NULL))
@@ -2190,6 +2193,8 @@ setup_source (GstURISourceBin * urisrc)
   } else {
     GstIterator *pads_iter;
     gboolean done = FALSE;
+
+    /* Expose all non-raw srcpads */
     pads_iter = gst_element_iterate_src_pads (urisrc->source);
     while (!done) {
       GValue item = { 0, };
@@ -2197,8 +2202,7 @@ setup_source (GstURISourceBin * urisrc)
 
       switch (gst_iterator_next (pads_iter, &item)) {
         case GST_ITERATOR_ERROR:
-            GST_WARNING_OBJECT (urisrc,
+          GST_WARNING_OBJECT (urisrc, "Error iterating pads on source element");
-                "Error iterating pads on source element");
           /* FALLTHROUGH */
         case GST_ITERATOR_DONE:
           done = TRUE;
@@ -2219,7 +2223,7 @@ setup_source (GstURISourceBin * urisrc)
     }
     gst_iterator_free (pads_iter);
   }
-  }
+
   return TRUE;
 
   /* ERRORS */