diff --git a/lib/gst/plugin/gstgtkutils.c b/lib/gst/plugin/gstgtkutils.c
index 19cf233b..4570726f 100644
--- a/lib/gst/plugin/gstgtkutils.c
+++ b/lib/gst/plugin/gstgtkutils.c
@@ -140,3 +140,23 @@ gst_video_frame_into_gdk_texture (GstVideoFrame *frame)
 
   return texture;
 }
+
+void
+gst_gtk_get_width_height_for_rotation (gint width, gint height,
+    gint *out_width, gint *out_height,
+    GstVideoOrientationMethod rotation)
+{
+  switch (rotation) {
+    case GST_VIDEO_ORIENTATION_90R:
+    case GST_VIDEO_ORIENTATION_90L:
+    case GST_VIDEO_ORIENTATION_UL_LR:
+    case GST_VIDEO_ORIENTATION_UR_LL:
+      *out_width = height;
+      *out_height = width;
+      break;
+    default:
+      *out_width = width;
+      *out_height = height;
+      break;
+  }
+}
diff --git a/lib/gst/plugin/gstgtkutils.h b/lib/gst/plugin/gstgtkutils.h
index 3e8fa5dc..972eccba 100644
--- a/lib/gst/plugin/gstgtkutils.h
+++ b/lib/gst/plugin/gstgtkutils.h
@@ -32,4 +32,8 @@ gpointer        gst_gtk_invoke_on_main                (GThreadFunc func, gpointe
 
 GdkTexture *    gst_video_frame_into_gdk_texture      (GstVideoFrame *frame);
 
+void            gst_gtk_get_width_height_for_rotation (gint width, gint height,
+                                                       gint *out_width, gint *out_height,
+                                                       GstVideoOrientationMethod rotation);
+
 G_END_DECLS