basetextoverlay: Rewrite negotiation method

This cleanup the negotiation function by properly splitting the probe
and the decisions. This allow handling correctly pipeline where upstream
caps have special memory type. An example pipeline is:

  gltestsrc ! textoverlay text=bla ! fakesink

The upstream caps will be memory:GLMemory, which isn't supported by the
blitter.

https://bugzilla.gnome.org/show_bug.cgi?id=749243

diff --git a/ext/pango/gstbasetextoverlay.c b/ext/pango/gstbasetextoverlay.c
index e76e2d21fa1c5eeeef7a5a29ed23deacad87f399..9c7aba7a920d703e3843198429d6d0e944b08b11 100644 (file)
--- a/ext/pango/gstbasetextoverlay.c
+++ b/ext/pango/gstbasetextoverlay.c
@@ -669,14 +669,13 @@ gst_base_text_overlay_setcaps_txt (GstBaseTextOverlay * overlay, GstCaps * caps)
 static gboolean
 gst_base_text_overlay_negotiate (GstBaseTextOverlay * overlay, GstCaps * caps)
 {
-  GstQuery *query;
+  gboolean upstream_has_meta = FALSE;
+  gboolean caps_has_meta = FALSE;
+  gboolean alloc_has_meta = FALSE;
   gboolean attach = FALSE;
-  gboolean caps_has_meta = TRUE;
-  gboolean ret;
+  gboolean ret = TRUE;
   GstCapsFeatures *f;
-  GstCaps *original_caps;
-  gboolean original_has_meta = FALSE;
-  gboolean allocation_ret = TRUE;
+  GstCaps *overlay_caps;
 
   GST_DEBUG_OBJECT (overlay, "performing negotiation");
 
@@ -688,76 +687,77 @@ gst_base_text_overlay_negotiate (GstBaseTextOverlay * overlay, GstCaps * caps)
   if (!caps || gst_caps_is_empty (caps))
     goto no_format;
 
-  original_caps = caps;
-
-  /* Try to use the overlay meta if possible */
-  f = gst_caps_get_features (caps, 0);
-
-  /* if the caps doesn't have the overlay meta, we query if downstream
-   * accepts it before trying the version without the meta
-   * If upstream already is using the meta then we can only use it */
-  if (!f
-      || !gst_caps_features_contains (f,
-          GST_CAPS_FEATURE_META_GST_VIDEO_OVERLAY_COMPOSITION)) {
-    GstCaps *overlay_caps;
-
-    /* In this case we added the meta, but we can work without it
-     * so preserve the original caps so we can use it as a fallback */
-    overlay_caps = gst_caps_copy (caps);
-
-    f = gst_caps_get_features (overlay_caps, 0);
-    gst_caps_features_add (f,
+  /* Check if upstream caps have meta */
+  if ((f = gst_caps_get_features (caps, 0))) {
+    caps_has_meta = gst_caps_features_contains (f,
         GST_CAPS_FEATURE_META_GST_VIDEO_OVERLAY_COMPOSITION);
+  }
 
-    ret = gst_pad_peer_query_accept_caps (overlay->srcpad, overlay_caps);
-    GST_DEBUG_OBJECT (overlay, "Downstream accepts the overlay meta: %d", ret);
-    if (ret) {
-      gst_caps_unref (caps);
-      caps = overlay_caps;
-
-    } else {
-      /* fallback to the original */
-      gst_caps_unref (overlay_caps);
-      caps_has_meta = FALSE;
-    }
+  if (upstream_has_meta) {
+    overlay_caps = gst_caps_ref (caps);
   } else {
-    original_has_meta = TRUE;
-  }
-  GST_DEBUG_OBJECT (overlay, "Using caps %" GST_PTR_FORMAT, caps);
-  ret = gst_pad_set_caps (overlay->srcpad, caps);
+    GstQuery *query;
 
-  if (ret) {
-    /* find supported meta */
+    /* First check if the allocation meta has compositon */
     query = gst_query_new_allocation (caps, FALSE);
 
     if (!gst_pad_peer_query (overlay->srcpad, query)) {
       /* no problem, we use the query defaults */
       GST_DEBUG_OBJECT (overlay, "ALLOCATION query failed");
-      allocation_ret = FALSE;
+
+      /* In case we were flushing, mark reconfigure and fail this method,
+       * will make it retry */
+      if (overlay->video_flushing)
+        ret = FALSE;
     }
 
-    if (caps_has_meta && gst_query_find_allocation_meta (query,
-            GST_VIDEO_OVERLAY_COMPOSITION_META_API_TYPE, NULL))
-      attach = TRUE;
+    alloc_has_meta = gst_query_find_allocation_meta (query,
+        GST_VIDEO_OVERLAY_COMPOSITION_META_API_TYPE, NULL);
 
     gst_query_unref (query);
+
+    /* Then check if downstream accept overlay composition in caps */
+    overlay_caps = gst_caps_copy (caps);
+
+    f = gst_caps_get_features (overlay_caps, 0);
+    gst_caps_features_add (f,
+        GST_CAPS_FEATURE_META_GST_VIDEO_OVERLAY_COMPOSITION);
+
+    caps_has_meta = gst_pad_peer_query_accept_caps (overlay->srcpad,
+        overlay_caps);
   }
 
-  overlay->attach_compo_to_buffer = attach;
+  /* For backward compatbility, we will prefer bliting if downstream
+   * allocation does not support the meta. In other case we will prefer
+   * attaching, and will fail the negotiation in the unlikely case we are
+   * force to blit, but format isn't supported. */
 
-  if (!allocation_ret && overlay->video_flushing) {
-    ret = FALSE;
-  } else if (original_caps && !original_has_meta && !attach) {
-    if (caps_has_meta) {
-      /* Some elements (fakesink) claim to accept the meta on caps but won't
-         put it in the allocation query result, this leads below
-         check to fail. Prevent this by removing the meta from caps */
-      gst_caps_unref (caps);
-      caps = gst_caps_ref (original_caps);
-      ret = gst_pad_set_caps (overlay->srcpad, caps);
-      if (ret && !gst_base_text_overlay_can_handle_caps (caps))
-        ret = FALSE;
+  if (upstream_has_meta) {
+    attach = TRUE;
+  } else if (caps_has_meta) {
+    if (alloc_has_meta) {
+      attach = TRUE;
+    } else {
+      /* Don't attach unless we cannot handle the format */
+      attach = !gst_base_text_overlay_can_handle_caps (caps);
     }
+  } else {
+    ret = gst_base_text_overlay_can_handle_caps (caps);
+  }
+
+  /* If we attach, then pick the overlay caps */
+  if (attach) {
+    gst_caps_unref (caps);
+    caps = overlay_caps;
+  } else {
+    gst_caps_unref (overlay_caps);
+  }
+
+  /* If negotiation worked, set the caps and remember to attach */
+  if (ret) {
+    GST_DEBUG_OBJECT (overlay, "Using caps %" GST_PTR_FORMAT, caps);
+    overlay->attach_compo_to_buffer = attach;
+    ret = gst_pad_set_caps (overlay->srcpad, caps);
   }
 
   if (!ret) {