in mqtt-publish-sample/mqttpublisher-gstreamer-plugin/mqttpublisher/gstmqttpublisher.cc [115:127]
static void gst_mqtt_publisher_set_property(GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) {
GstMqttPublisher *filter = GST_MQTTPUBLISHER(object);
switch (prop_id) {
case PROP_PUBLISH_TOPIC:
g_free(filter->publish_topic);
filter->publish_topic = g_strdup(g_value_get_string(value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
break;
}
}