ffplay: use format title metadata to set window caption.

ffplay.c

@@ -2725,6 +2725,9 @@ static int read_thread(void *arg)
 
     is->max_frame_duration = (ic->iformat->flags & AVFMT_TS_DISCONT) ? 10.0 : 3600.0;
 
+    if (!window_title && (t = av_dict_get(ic->metadata, "title", NULL, 0)))
+        window_title = av_asprintf("%s - %s", t->value, input_filename);
+
     /* if seeking requested, we execute it */
     if (start_time != AV_NOPTS_VALUE) {
         int64_t timestamp;