basetransform: Refactor gst_base_transform_buffer_alloc() code

Don't check if upstream provided caps are compatible with upstream
and don't try to fixate these caps. They must be fixated in any case.

libs/gst/base/gstbasetransform.c

@@ -1828,7 +1828,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
   GstBaseTransformPrivate *priv;
   GstFlowReturn res;
   gboolean alloced = FALSE;
-  gboolean proxy, suggest, same_caps;
+  gboolean proxy, suggest, new_caps;
   GstCaps *sink_suggest = NULL;
   guint size_suggest;
 
@@ -1850,32 +1850,33 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
   /* we remember our previous alloc request to quickly see if we can proxy or
    * not. We skip this check if we have a pending suggestion. */
   GST_OBJECT_LOCK (pad);
-  same_caps = !priv->suggest_pending && caps &&
+  suggest = priv->suggest_pending;
-      gst_caps_is_equal (priv->sink_alloc, caps);
   GST_OBJECT_UNLOCK (pad);
 
-  if (same_caps) {
+  if (!suggest) {
-    /* we have seen this before, see below if we need to proxy */
+    /* we have no suggestion, see below if we need to proxy */
-    GST_DEBUG_OBJECT (trans, "have old caps %p, size %u", caps, size);
     gst_caps_replace (&sink_suggest, caps);
     size_suggest = size;
     suggest = FALSE;
-  } else {
+    new_caps = sink_suggest
-    GST_DEBUG_OBJECT (trans, "new format %p %" GST_PTR_FORMAT, caps, caps);
+        && !gst_caps_is_equal (sink_suggest, priv->sink_alloc);
 
+    if (new_caps)
+      GST_DEBUG_OBJECT (trans, "new format %p %" GST_PTR_FORMAT, caps, caps);
+    else
+      GST_DEBUG_OBJECT (trans, "have old caps %p, size %u", caps, size);
+  } else {
     /* if we have a suggestion, pretend we got these as input */
     GST_OBJECT_LOCK (pad);
-    if ((priv->sink_suggest && !gst_caps_is_equal (caps, priv->sink_suggest))) {
+    if (priv->sink_suggest && !gst_caps_is_equal (caps, priv->sink_suggest)) {
       sink_suggest = gst_caps_ref (priv->sink_suggest);
       size_suggest = priv->size_suggest;
       GST_DEBUG_OBJECT (trans, "have suggestion %p %" GST_PTR_FORMAT " size %u",
           sink_suggest, sink_suggest, priv->size_suggest);
-      /* suggest is TRUE when we have a custom suggestion pending that we need
-       * to unref later. */
-      suggest = TRUE;
     } else {
-      GST_DEBUG_OBJECT (trans, "using caps %p %" GST_PTR_FORMAT " size %u",
+      GST_DEBUG_OBJECT (trans,
-          caps, caps, size);
+          "have suggestion equal to upstream caps %p %" GST_PTR_FORMAT, caps,
+          caps);
       gst_caps_replace (&sink_suggest, caps);
       size_suggest = size;
       suggest = FALSE;
@@ -1884,8 +1885,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
     GST_OBJECT_UNLOCK (pad);
 
     /* check if we actually handle this format on the sinkpad */
-    if (sink_suggest) {
+    if (suggest) {
-      const GstCaps *templ;
       GstCaps *peercaps;
 
       /* Always intersect with the peer caps to get correct
@@ -1944,13 +1944,19 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
         GST_DEBUG_OBJECT (trans, "Caps fixed to: %" GST_PTR_FORMAT,
             sink_suggest);
       }
+    }
 
-      /* Check if the suggested caps are compatible with our
+    new_caps = sink_suggest
-       * sinkpad template caps and if they're not (or were
+        && !gst_caps_is_equal (sink_suggest, priv->sink_alloc);
-       * empty after intersecting with the peer caps above)
+  }
+
+  /* Check if the new caps are compatible with our
+   * sinkpad template caps and if they're not
    * we try to come up with any supported caps
    */
-      if (sink_suggest) {
+  if (new_caps) {
+    const GstCaps *templ;
+
     templ = gst_pad_get_pad_template_caps (pad);
 
     if (!gst_caps_can_intersect (sink_suggest, templ)) {
@@ -1984,6 +1990,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
         gst_caps_unref (allowed);
 
         suggest = TRUE;
+        new_caps = !gst_caps_is_equal (sink_suggest, priv->sink_alloc);
 
         GST_DEBUG_OBJECT (trans, "Fixated suggestion caps to %"
             GST_PTR_FORMAT, sink_suggest);
@@ -1994,7 +2001,6 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
       }
     }
   }
-    }
 
   /* find the best format for the other side here we decide if we will proxy
    * the caps or not. */
@@ -2003,7 +2009,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
      * we can proxy it downstream */
     GST_DEBUG_OBJECT (trans, "null caps, marking for proxy");
     priv->proxy_alloc = TRUE;
-    } else {
+  } else if (new_caps) {
     GstCaps *othercaps;
 
     /* we have a new format, see what we need to proxy to */
@@ -2015,8 +2021,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
     } else {
       /* we transformed into something */
       if (gst_caps_is_equal (sink_suggest, othercaps)) {
-          GST_DEBUG_OBJECT (trans,
+        GST_DEBUG_OBJECT (trans, "best caps same as input, marking for proxy");
-              "best caps same as input, marking for proxy");
         priv->proxy_alloc = TRUE;
       } else {
         GST_DEBUG_OBJECT (trans,
@@ -2027,7 +2032,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
     if (othercaps)
       gst_caps_unref (othercaps);
   }
-  }
+
   /* remember the new caps */
   GST_OBJECT_LOCK (pad);
   gst_caps_replace (&priv->sink_alloc, sink_suggest);
@@ -2079,9 +2084,7 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
     } else {
       GST_DEBUG_OBJECT (trans, "received required caps from peer");
     }
-  }
+  } else if (suggest) {
-
-  if (suggest) {
     /* there was a custom suggestion, create a buffer of this format and return
      * it. Note that this format  */
     *buf = gst_buffer_new_and_alloc (size_suggest);
@@ -2090,6 +2093,9 @@ gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,
         sink_suggest, sink_suggest);
     GST_BUFFER_CAPS (*buf) = sink_suggest;
     sink_suggest = NULL;
+  } else {
+    /* fallback buffer allocation by gst_pad_alloc_buffer() with the
+     * caps and size provided by the caller */
   }
 
   if (sink_suggest)