if (avfilter_graph_create_filter (&_buffer_sink_context, buffer_sink, N_("out"), 0, sink_params, graph) < 0) {
throw DecodeError (N_("could not create buffer sink."));
}
if (avfilter_graph_create_filter (&_buffer_sink_context, buffer_sink, N_("out"), 0, sink_params, graph) < 0) {
throw DecodeError (N_("could not create buffer sink."));
}