videodecoder: getters for pool and allocator

Sometimes the decoder would need to use the pool or the allocator for
something else than just allocating output buffers. For example, the querying
for different parameters, such as asking for a bigger number of buffers to
allocate in the pool.

This patch expose a two getters accessors: one for the buffer pool and the
other for the memory allocator.

gst-libs/gst/video/gstvideodecoder.c

@@ -3141,3 +3141,48 @@ gst_video_decoder_merge_tags (GstVideoDecoder * decoder,
   decoder->priv->tags_changed = TRUE;
   GST_VIDEO_DECODER_STREAM_UNLOCK (decoder);
 }
+
+/**
+ * gst_video_decoder_get_buffer_pool:
+ * @decoder: a #GstVideoDecoder
+ *
+ * Returns: (transfer full): the instance of the #GstBufferPool used
+ * by the decoder; free it after use it
+ */
+GstBufferPool *
+gst_video_decoder_get_buffer_pool (GstVideoDecoder * decoder)
+{
+  g_return_val_if_fail (GST_IS_VIDEO_DECODER (decoder), NULL);
+
+  if (decoder->priv->pool)
+    return gst_object_ref (decoder->priv->pool);
+
+  return NULL;
+}
+
+/**
+ * gst_video_decoder_get_allocator:
+ * @decoder: a #GstVideoDecoder
+ * @allocator: (out) (allow-none) (transfer full): the #GstAllocator
+ * used
+ * @params: (out) (allow-none) (transfer full): the
+ * #GstAllocatorParams of @allocator
+ *
+ * Lets #GstVideoDecoder sub-classes to know the memory @allocator
+ * used by the base class and its @params.
+ *
+ * Unref the @allocator after use it.
+ */
+void
+gst_video_decoder_get_allocator (GstVideoDecoder * decoder,
+    GstAllocator ** allocator, GstAllocationParams * params)
+{
+  g_return_if_fail (GST_IS_VIDEO_DECODER (decoder));
+
+  if (allocator)
+    *allocator = decoder->priv->allocator ?
+        gst_object_ref (decoder->priv->allocator) : NULL;
+
+  if (params)
+    *params = decoder->priv->params;
+}

gst-libs/gst/video/gstvideodecoder.h

@@ -309,6 +309,10 @@ void     gst_video_decoder_get_latency (GstVideoDecoder *decoder,
 					GstClockTime *min_latency,
 					GstClockTime *max_latency);
 
+void     gst_video_decoder_get_allocator (GstVideoDecoder *decoder,
+                                          GstAllocator **allocator,
+                                          GstAllocationParams *params);
+GstBufferPool *gst_video_decoder_get_buffer_pool (GstVideoDecoder *decoder);
 
 /* Object methods */