transcode: Reset frametype to prevent encoder problems

transcode.c

@@ -203,6 +203,7 @@ static void flush_filtergraph(AVFormatContext *mux, AVFilterContext **sinks, AVC
 	for (i = 0; i < mux->nb_streams; i ++)
 		while (av_buffersink_get_frame(sinks[i], frame) >= 0)
 		{
+			frame->pict_type = AV_PICTURE_TYPE_NONE;
 			avcodec_send_frame(encs[i], frame);
 			av_frame_unref(frame);
 			flush_encoder(mux, sinks[i], encs[i], i);