[pipe] Added instant volume support (pvol) to named metadata pipe.

src/inputs/pipe.c

@@ -302,6 +302,47 @@ parse_progress(struct input_metadata *m, char *progress)
   m->song_length = (end - start) * 10 / 441; // Convert to ms based on 44100
 }
 
+static void
+parse_volume(char *volume)
+{
+  char *volume_next;
+  float airplay_volume;
+  float local_volume;
+
+  errno = 0;
+  airplay_volume = strtof(volume, &volume_next);
+
+  if ((errno == ERANGE) || (volume == volume_next))
+    {
+      DPRINTF(E_LOG, L_PLAYER, "Invalid airplay volume in string (%s): %s\n", volume,
+	      (errno == ERANGE ? strerror(errno) : "First token is not a number."));
+      return;
+    }
+
+  if (strcmp(volume_next, ",0.00,0.00,0.00") != 0)
+    {
+      DPRINTF(E_DBG, L_PLAYER, "Not applying airplay volume while software volume control is enabled (%s)\n", volume);
+      return;
+    }
+
+  if (((int) airplay_volume) == -144)
+    {
+      DPRINTF(E_DBG, L_PLAYER, "Applying airplay volume ('mute', value: %.2f)\n", airplay_volume);
+      player_volume_set(0);
+    }
+  else if (airplay_volume >= -30.0 && airplay_volume <= 0.0)
+    {
+      local_volume = 100.0 + (airplay_volume / 30.0 * 100.0);
+      if (local_volume < 0 || local_volume > 100)
+	return;
+
+      DPRINTF(E_DBG, L_PLAYER, "Applying airplay volume (percent: %.0f, value: %.2f)\n", local_volume, airplay_volume);
+      player_volume_set((int) local_volume);
+    }
+  else
+    DPRINTF(E_LOG, L_PLAYER, "Airplay volume out of range (-144.0, [-30.0 - 0.0]): %.2f\n", airplay_volume);
+}
+
 // returns 1 on metadata found, 0 on nothing, -1 on error
 static int
 parse_item(struct input_metadata *m, const char *item)
@@ -313,6 +354,7 @@ parse_item(struct input_metadata *m, const char *item)
   uint32_t type;
   uint32_t code;
   char *progress;
+  char *volume;
   char **data;
   int ret;
 
@@ -356,6 +398,8 @@ parse_item(struct input_metadata *m, const char *item)
     data = &m->genre;
   else if (code == dmapval("prgr"))
     data = &progress;
+  else if (code == dmapval("pvol"))
+    data = &volume;
   else
     goto out_nothing;
 
@@ -364,7 +408,7 @@ parse_item(struct input_metadata *m, const char *item)
     {
       pthread_mutex_lock(&pipe_metadata_lock);
 
-      if (data != &progress)
+      if (data != &progress && data != &volume)
 	free(*data);
 
       *data = b64_decode(s);
@@ -376,6 +420,11 @@ parse_item(struct input_metadata *m, const char *item)
 	  parse_progress(m, progress);
 	  free(*data);
 	}
+      else if (data == &volume)
+	{
+	  parse_volume(volume);
+	  free(*data);
+	}
 
       pthread_mutex_unlock(&pipe_metadata_lock);
 
@@ -910,4 +959,3 @@ struct input_definition input_pipe =
   .init = init,
   .deinit = deinit,
 };
-