libs/gst/base/gstbasetransform.*: Add vmethod that is called before we start the transform and which can be used to c...

Original commit message from CVS:
* libs/gst/base/gstbasetransform.c:
(gst_base_transform_prepare_output_buffer),
(gst_base_transform_getrange), (gst_base_transform_chain):
* libs/gst/base/gstbasetransform.h:
Add vmethod that is called before we start the transform and which can
be used to configure the transform, such as dynamic properties.

ChangeLog

@@ -1,3 +1,12 @@
+2008-12-08  Wim Taymans  <wim.taymans@collabora.co.uk>
+
+	* libs/gst/base/gstbasetransform.c:
+	(gst_base_transform_prepare_output_buffer),
+	(gst_base_transform_getrange), (gst_base_transform_chain):
+	* libs/gst/base/gstbasetransform.h:
+	Add vmethod that is called before we start the transform and which can
+	be used to configure the transform, such as dynamic properties.
+
 2008-12-05  David Schleef  <ds@schleef.org>
 
 	* gst/gst.c:

libs/gst/base/gstbasetransform.c

@@ -1185,6 +1185,7 @@ gst_base_transform_prepare_output_buffer (GstBaseTransform * trans,
       /* only discard it when the input was not writable, otherwise, we reuse
        * the input buffer. */
       discard = gst_buffer_is_writable (in_buf);
+      GST_DEBUG_OBJECT (trans, "discard: %d", discard);
     } else {
       GST_DEBUG_OBJECT (trans, "getting output size for copy transform");
       /* copy transform, figure out the output size */
@@ -1948,6 +1949,7 @@ gst_base_transform_getrange (GstPad * pad, guint64 offset,
     guint length, GstBuffer ** buffer)
 {
   GstBaseTransform *trans;
+  GstBaseTransformClass *klass;
   GstFlowReturn ret;
   GstBuffer *inbuf;
 
@@ -1957,6 +1959,10 @@ gst_base_transform_getrange (GstPad * pad, guint64 offset,
   if (G_UNLIKELY (ret != GST_FLOW_OK))
     goto pull_error;
 
+  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);
+  if (klass->before_transform)
+    klass->before_transform (trans, inbuf);
+
   GST_BASE_TRANSFORM_LOCK (trans);
   ret = gst_base_transform_handle_buffer (trans, inbuf, buffer);
   GST_BASE_TRANSFORM_UNLOCK (trans);
@@ -1979,6 +1985,7 @@ static GstFlowReturn
 gst_base_transform_chain (GstPad * pad, GstBuffer * buffer)
 {
   GstBaseTransform *trans;
+  GstBaseTransformClass *klass;
   GstFlowReturn ret;
   GstClockTime last_stop = GST_CLOCK_TIME_NONE;
   GstBuffer *outbuf = NULL;
@@ -1993,6 +2000,10 @@ gst_base_transform_chain (GstPad * pad, GstBuffer * buffer)
       last_stop = GST_BUFFER_TIMESTAMP (buffer);
   }
 
+  klass = GST_BASE_TRANSFORM_GET_CLASS (trans);
+  if (klass->before_transform)
+    klass->before_transform (trans, buffer);
+
   /* protect transform method and concurrent buffer alloc */
   GST_BASE_TRANSFORM_LOCK (trans);
   ret = gst_base_transform_handle_buffer (trans, buffer, &outbuf);

libs/gst/base/gstbasetransform.h

@@ -182,6 +182,10 @@ struct _GstBaseTransform {
  *                         analysis can return a subbuffer or even just
  *                         increment the reference to the input buffer (if in
  *                         passthrough mode)
+ * @before_transform: Optional. Since 0.10.22
+ *                    This method is called right before the base class will
+ *                    start processing. Dynamic properties or other delayed
+ *                    configuration could be performed in this method.
  *
  * Subclasses can override any of the available virtual methods or not, as
  * needed. At minimum either @transform or @transform_ip need to be overridden.
@@ -231,8 +235,10 @@ struct _GstBaseTransformClass {
   /* src event */
   gboolean      (*src_event)      (GstBaseTransform *trans, GstEvent *event);
 
+  void          (*before_transform)  (GstBaseTransform *trans, GstBuffer *buffer);
+
   /*< private >*/
-  gpointer       _gst_reserved[GST_PADDING_LARGE - 1];
+  gpointer       _gst_reserved[GST_PADDING_LARGE - 2];
 };
 
 GType           gst_base_transform_get_type         (void);