Add code to try to save your ears by handling a situation where the player volume was set very high some time ago and you have forgotten.

In that situation currenctly, when you play something, it will come out at the last volume set on the device, which will be that very high volume.
This could happen, for example, the morning after a loud party :).

The new code works as follows: If nothing has been played for a period, say a few hours, and the volume is higher than a threshold, new connections that ask
for the current volume setting will be offered the default (low) volume rather than the current (very high) one.
Most players, including the HomePod mini, iOS and iPadOS use this to set their initial volume.
The Mac Music app retains its own setting, and the Mac System Sounds preference sometimes seems to take its setting from the Music app,
but at least you can see the settings they will apply.

Existing connections are unaffected, so this facility should be unobtrusive.

player.c

@@ -1702,6 +1702,41 @@ void statistics_item(const char *heading, const char *format, ...) {
   statistics_column++;
 }
 
+double suggested_volume(rtsp_conn_info *conn) {
+  double response = config.airplay_volume;
+  if (conn) {
+    if (conn->own_airplay_volume_set != 0) {
+      response = conn->own_airplay_volume;
+    } else if (config.airplay_volume > config.high_threshold_airplay_volume) {
+      int64_t volume_validity_time = config.limit_to_high_volume_threshold_time_in_minutes;
+      // zero means never check the volume
+      if (volume_validity_time != 0) {
+        // If the volume is higher than the high volume threshold
+        // and enough time has gone past, suggest the default volume.
+        uint64_t time_now = get_absolute_time_in_ns();
+        int64_t time_since_last_access_to_volume_info =
+            time_now - config.last_access_to_volume_info_time;
+
+        volume_validity_time = volume_validity_time * 60;         // to seconds
+        volume_validity_time = volume_validity_time * 1000000000; // to nanoseconds
+
+        if ((config.airplay_volume > config.high_threshold_airplay_volume) &&
+            ((config.last_access_to_volume_info_time == 0) ||
+             (time_since_last_access_to_volume_info > volume_validity_time))) {
+
+          debug(2,
+                "the current volume %.6f is higher than the high volume threshold %.6f, so the "
+                "default volume %.6f is suggested.",
+                config.airplay_volume, config.high_threshold_airplay_volume,
+                config.default_airplay_volume);
+          response = config.default_airplay_volume;
+        }
+      }
+    }
+  }
+  return response;
+}
+
 void player_thread_cleanup_handler(void *arg) {
   rtsp_conn_info *conn = (rtsp_conn_info *)arg;
   if (pthread_mutex_trylock(&playing_conn_lock) == 0) {
@@ -2192,9 +2227,11 @@ void *player_thread_func(void *arg) {
 
   pthread_setcancelstate(oldState, NULL);
 
-  double initial_volume = config.airplay_volume; // default
-  // set the default volume to whatever it was before, as stored in the config airplay_volume
-  debug(2, "Set initial volume to %f.", initial_volume);
+  // if not already set, set the volume to the pending_airplay_volume, if any, or otherwise to the
+  // suggested volume.
+
+  double initial_volume = suggested_volume(conn);
+  debug(2, "Set initial volume to %.6f.", initial_volume);
   player_volume(initial_volume, conn); // will contain a cancellation point if asked to wait
 
   debug(2, "Play begin");
@@ -2216,6 +2253,9 @@ void *player_thread_func(void *arg) {
     abuf_t *inframe = buffer_get_frame(conn); // this has cancellation point(s), but it's not
                                               // guaranteed that they'll always be executed
     uint64_t local_time_now = get_absolute_time_in_ns(); // types okay
+    config.last_access_to_volume_info_time =
+        local_time_now; // ensure volume info remains seen as valid
+
     if (inframe) {
       inbuf = inframe->data;
       inbuflength = inframe->length;
@@ -3462,6 +3502,7 @@ void player_volume_without_notification(double airplay_volume, rtsp_conn_info *c
   }
   // here, store the volume for possible use in the future
   config.airplay_volume = airplay_volume;
+  conn->own_airplay_volume = airplay_volume;
   debug_mutex_unlock(&conn->volume_control_mutex, 3);
 }