basetransform: add vmethod to configure upstream bufferpool

Add a vmethod that can be implemented to influence the bufferpool that upstream
elements will use.

diff --git a/libs/gst/base/gstbasetransform.c b/libs/gst/base/gstbasetransform.c
index 6550cb0..cb632d7 100644 (file)
--- a/libs/gst/base/gstbasetransform.c
+++ b/libs/gst/base/gstbasetransform.c
@@ -1324,12 +1324,23 @@ gst_base_transform_default_query (GstBaseTransform * trans,
       passthrough = trans->passthrough || trans->always_in_place;
       GST_BASE_TRANSFORM_UNLOCK (trans);
 
-      GST_DEBUG_OBJECT (trans, "passthrough %d", passthrough);
-
-      if (passthrough)
+      if (passthrough) {
+        GST_DEBUG_OBJECT (trans, "doing passthrough query");
         ret = gst_pad_peer_query (otherpad, query);
-      else
-        ret = FALSE;
+      } else {
+        GstBaseTransformClass *klass;
+
+        GST_DEBUG_OBJECT (trans, "deciding on allocation values");
+
+        klass = GST_BASE_TRANSFORM_GET_CLASS (trans);
+        /* pass the query to the decide_allocation vmethod if any */
+        if (G_LIKELY (klass->decide_allocation))
+          ret = klass->decide_allocation (trans, query);
+        else
+          ret = FALSE;
+      }
+      GST_DEBUG_OBJECT (trans, "ALLOCATION ret %d, %" GST_PTR_FORMAT, ret,
+          query);
       break;
     }
     case GST_QUERY_POSITION:

diff --git a/libs/gst/base/gstbasetransform.h b/libs/gst/base/gstbasetransform.h
index 521101a..da47fb7 100644 (file)
--- a/libs/gst/base/gstbasetransform.h
+++ b/libs/gst/base/gstbasetransform.h
@@ -162,11 +162,13 @@ struct _GstBaseTransform {
  *                  query
  * @decide_allocation: Decide what parameters you want upstream elements to use
  *                     for the allocation of buffers. This function is only
- *                     called when not operating in passthrough mode.
+ *                     called when not operating in passthrough mode. The
+ *                     default implementation is NULL.
  * @setup_allocation: Setup the allocation parameters for allocating output
  *                    buffers. The passed in query contains the result of the
  *                    downstream allocation query. This function is only called
- *                    when not operating in passthrough mode.
+ *                    when not operating in passthrough mode. The default
+ *                    implementation is NULL.
  * @transform_size: Optional. Given the size of a buffer in the given direction
  *                  with the given caps, calculate the size in bytes of a buffer
  *                  on the other pad with the given other caps.
@@ -180,12 +182,6 @@ struct _GstBaseTransform {
  * @stop:           Optional.
  *                  Called when the element stops processing.
  *                  Allows closing external resources.
- * @transform:      Required if the element does not operate in-place.
- *                  Transforms one incoming buffer to one outgoing buffer.
- *                  The function is allowed to change size/timestamp/duration
- *                  of the outgoing buffer.
- * @transform_ip:   Required if the element operates in-place.
- *                  Transform the incoming buffer in-place.
  * @sink_event:     Optional.
  *                  Event handler on the sink pad. The default implementation
  *                  handles the event and forwards it downstream.
@@ -209,6 +205,12 @@ struct _GstBaseTransform {
  *                    This method is called right before the base class will
  *                    start processing. Dynamic properties or other delayed
  *                    configuration could be performed in this method.
+ * @transform:      Required if the element does not operate in-place.
+ *                  Transforms one incoming buffer to one outgoing buffer.
+ *                  The function is allowed to change size/timestamp/duration
+ *                  of the outgoing buffer.
+ * @transform_ip:   Required if the element operates in-place.
+ *                  Transform the incoming buffer in-place.
  *
  * Subclasses can override any of the available virtual methods or not, as
  * needed. At minimum either @transform or @transform_ip need to be overridden.