ffplay: give more meaningful names to the buffersink instances

ffplay.c

@@ -1575,12 +1575,12 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
 #if FF_API_OLD_VSINK_API
     ret = avfilter_graph_create_filter(&filt_out,
                                        avfilter_get_by_name("buffersink"),
-                                       "out", NULL, (void *)pix_fmts, graph);
+                                       "ffplay_buffersink", NULL, (void *)pix_fmts, graph);
 #else
     buffersink_params->pixel_fmts = pix_fmts;
     ret = avfilter_graph_create_filter(&filt_out,
                                        avfilter_get_by_name("buffersink"),
-                                       "out", NULL, buffersink_params, graph);
+                                       "ffplay_buffersink", NULL, buffersink_params, graph);
 #endif
     av_freep(&buffersink_params);
     if (ret < 0)