pad: add GST_PAD_FLAG_ACCEPT_TEMPLATE

It will make the default accept-caps handler use the pad template
caps instead of the query-caps result to check if the caps is
acceptable. This is aligned with what the design docs says the
accept-caps should do (be non-recursive) and should be faster. It
is *not* enabled by default, though.

API: GST_PAD_FLAG_ACCEPT_TEMPLATE
API: GST_PAD_IS_ACCEPT_TEMPLATE
API: GST_PAD_SET_ACCEPT_TEMPLATE
API: GST_PAD_UNSET_ACCEPT_TEMPLATE

https://bugzilla.gnome.org/show_bug.cgi?id=753623

diff --git a/gst/gstpad.c b/gst/gstpad.c
index 89eec99..49a3e95 100644 (file)
--- a/gst/gstpad.c
+++ b/gst/gstpad.c
@@ -2972,7 +2972,10 @@ gst_pad_query_accept_caps_default (GstPad * pad, GstQuery * query)
       "fallback ACCEPT_CAPS query, consider implementing a specialized version");
 
   gst_query_parse_accept_caps (query, &caps);
-  allowed = gst_pad_query_caps (pad, caps);
+  if (GST_PAD_IS_ACCEPT_TEMPLATE (pad))
+    allowed = gst_pad_get_pad_template_caps (pad);
+  else
+    allowed = gst_pad_query_caps (pad, caps);
 
   if (allowed) {
     if (GST_PAD_IS_ACCEPT_INTERSECT (pad)) {

diff --git a/gst/gstpad.h b/gst/gstpad.h
index 32e6b15..7e64ac9 100644 (file)
--- a/gst/gstpad.h
+++ b/gst/gstpad.h
@@ -631,6 +631,10 @@ typedef gboolean  (*GstPadStickyEventsForeachFunction) (GstPad *pad, GstEvent **
  *                      it the caps intersect the query-caps result instead
  *                      of checking for a subset. This is interesting for
  *                      parsers that can accept incompletely specified caps.
+ * @GST_PAD_FLAG_ACCEPT_TEMPLATE: the default accept-caps handler will use
+ *                      the template pad caps instead of query caps to
+ *                      compare with the accept caps. Use this in combination
+ *                      with %GST_PAD_FLAG_ACCEPT_INTERSECT. (Since 1.6)
  * @GST_PAD_FLAG_LAST: offset to define more flags
  *
  * Pad state flags
@@ -648,6 +652,7 @@ typedef enum {
   GST_PAD_FLAG_PROXY_ALLOCATION = (GST_OBJECT_FLAG_LAST << 9),
   GST_PAD_FLAG_PROXY_SCHEDULING = (GST_OBJECT_FLAG_LAST << 10),
   GST_PAD_FLAG_ACCEPT_INTERSECT = (GST_OBJECT_FLAG_LAST << 11),
+  GST_PAD_FLAG_ACCEPT_TEMPLATE  = (GST_OBJECT_FLAG_LAST << 12),
   /* padding */
   GST_PAD_FLAG_LAST        = (GST_OBJECT_FLAG_LAST << 16)
 } GstPadFlags;
@@ -1117,6 +1122,38 @@ struct _GstPadClass {
  */
 #define GST_PAD_UNSET_ACCEPT_INTERSECT(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_ACCEPT_INTERSECT))
 /**
+ * GST_PAD_IS_ACCEPT_TEMPLATE:
+ * @pad: a #GstPad
+ *
+ * Check if the pad's accept caps operation will use the pad template caps.
+ * The default accept-caps will do a query caps to get the caps, which might
+ * be querying downstream causing unnecessary overhead. It is recommended to
+ * implement a proper accept-caps query handler or to use this flag to prevent
+ * recursive accept-caps handling.
+ *
+ * Since: 1.6
+ */
+#define GST_PAD_IS_ACCEPT_TEMPLATE(pad)    (GST_OBJECT_FLAG_IS_SET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
+/**
+ * GST_PAD_SET_ACCEPT_TEMPLATE:
+ * @pad: a #GstPad
+ *
+ * Set @pad to by default use the pad template caps to compare with
+ * the accept caps instead of using a caps query result.
+ *
+ * Since: 1.6
+ */
+#define GST_PAD_SET_ACCEPT_TEMPLATE(pad)   (GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
+/**
+ * GST_PAD_UNSET_ACCEPT_TEMPLATE:
+ * @pad: a #GstPad
+ *
+ * Unset accept template flag.
+ *
+ * Since: 1.6
+ */
+#define GST_PAD_UNSET_ACCEPT_TEMPLATE(pad) (GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_ACCEPT_TEMPLATE))
+/**
  * GST_PAD_GET_STREAM_LOCK:
  * @pad: a #GstPad
  *