libs: encoder: add gst_vaapi_encoder_get_surface_formats()

This method will return the valid surface formats in the current
config. If the are no VAConfig it is created with the information
available.

https://bugzilla.gnome.org/show_bug.cgi?id=769266

Signed-off-by: Víctor Manuel Jáquez Leal <victorx.jaquez@intel.com>

gst-libs/gst/vaapi/gstvaapiencoder.c

@@ -1153,6 +1153,35 @@ error:
   }
 }
 
+static gboolean
+gst_vaapi_encoder_ensure_context_config (GstVaapiEncoder * encoder)
+{
+  GstVaapiContextInfo *const cip = &encoder->context_info;
+
+  if (encoder->context)
+    return TRUE;
+
+  init_context_info (encoder);
+  encoder->context = gst_vaapi_context_new (encoder->display, cip);
+  return (encoder->context != NULL);
+}
+
+/**
+ * gst_vaapi_encoder_get_surface_formats:
+ * @encoder: a #GstVaapiEncoder instances
+ *
+ * Fetches the valid surface formats for the current VAConfig
+ *
+ * Returns: a #GArray of valid formats for the current VAConfig
+ **/
+GArray *
+gst_vaapi_encoder_get_surface_formats (GstVaapiEncoder * encoder)
+{
+  if (!gst_vaapi_encoder_ensure_context_config (encoder))
+    return NULL;
+  return gst_vaapi_context_get_surface_formats (encoder->context);
+}
+
 /** Returns a GType for the #GstVaapiEncoderTune set */
 GType
 gst_vaapi_encoder_tune_get_type (void)

gst-libs/gst/vaapi/gstvaapiencoder.h

@@ -173,6 +173,8 @@ gst_vaapi_encoder_get_buffer_with_timeout (GstVaapiEncoder * encoder,
 GstVaapiEncoderStatus
 gst_vaapi_encoder_flush (GstVaapiEncoder * encoder);
 
+GArray *
+gst_vaapi_encoder_get_surface_formats (GstVaapiEncoder * encoder);
 G_END_DECLS
 
 #endif /* GST_VAAPI_ENCODER_H */