Treat the "mper" attribute as the 64-bit item that it is rather than a 32-bit item as hithereto. Output it as a hexadecimal number to correspond with the format of the track id obtained from AppleScript

dbus-service.c

@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include "config.h"
 
@@ -204,7 +205,7 @@ void dbus_metadata_watcher(struct metadata_bundle *argc, __attribute__((unused))
   // Add in the Track ID based on the 'mper' metadata if it is non-zero
   if (argc->item_id != 0) {
     char trackidstring[128];
-    snprintf(trackidstring, sizeof(trackidstring), "/org/gnome/ShairportSync/mper_%u",
+    snprintf(trackidstring, sizeof(trackidstring), "/org/gnome/ShairportSync/%" PRIX64 "",
              argc->item_id);
     GVariant *trackid = g_variant_new("o", trackidstring);
     g_variant_builder_add(dict_builder, "{sv}", "mpris:trackid", trackid);
@@ -517,7 +518,7 @@ gboolean notify_convolution_impulse_response_file_callback(ShairportSync *skelet
 #else
 gboolean notify_convolution_impulse_response_file_callback(__attribute__((unused)) ShairportSync *skeleton,
                                                 __attribute__((unused)) gpointer user_data) {
-  char *th = (char *)shairport_sync_get_convolution_impulse_response_file(skeleton);
+  __attribute__((unused)) char *th = (char *)shairport_sync_get_convolution_impulse_response_file(skeleton);
   return TRUE;
 }
 #endif

metadata_hub.c

@@ -5,7 +5,7 @@
  * then you need a metadata hub,
  * where everything is stored
  * This file is part of Shairport Sync.
- * Copyright (c) Mike Brady 2017--2019
+ * Copyright (c) Mike Brady 2017--2020
  * All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person
@@ -38,6 +38,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
+#include <inttypes.h>
 
 #include "config.h"
 
@@ -303,28 +304,33 @@ void metadata_hub_process_metadata(uint32_t type, uint32_t code, char *data, uin
   // all the following items of metadata are contained in one metadata packet
   // they are preceded by an 'ssnc' 'mdst' item and followed by an 'ssnc 'mden' item.
 
-  uint32_t ui;
   char *cs;
   int changed = 0;
   if (type == 'core') {
     switch (code) {
-    case 'mper':
-      ui = ntohl(*(uint32_t *)data);
-      debug(2, "MH Item ID seen: \"%u\" of length %u.", ui, length);
-      if (ui != metadata_store.item_id) {
-        metadata_store.item_id = ui;
-        metadata_store.item_id_changed = 1;
-        metadata_store.item_id_received = 1;
-        debug(2, "MH Item ID set to: \"%u\"", metadata_store.item_id);
-      }
+    case 'mper': {
+        // get the 64-bit number as a uint64_t by reading two uint32_t s and combining them
+        uint64_t vl = ntohl(*(uint32_t*)data); // get the high order 32 bits
+        vl = vl << 32; // shift them into the correct location
+        uint64_t ul = ntohl(*(uint32_t*)(data+sizeof(uint32_t))); // and the low order 32 bits
+        vl = vl + ul;
+        debug(2, "MH Item ID seen: \"%" PRIx64 "\" of length %u.", vl, length);
+        if (vl != metadata_store.item_id) {
+          metadata_store.item_id = vl;
+          metadata_store.item_id_changed = 1;
+          metadata_store.item_id_received = 1;
+          debug(2, "MH Item ID set to: \"%" PRIx64 "\"", metadata_store.item_id);
+        }
+      }      
       break;
-    case 'astm':
-      ui = ntohl(*(uint32_t *)data);
-      debug(2, "MH Song Time seen: \"%u\" of length %u.", ui, length);
-      if (ui != metadata_store.songtime_in_milliseconds) {
-        metadata_store.songtime_in_milliseconds = ui;
-        metadata_store.songtime_in_milliseconds_changed = 1;
-        debug(2, "MH Song Time set to: \"%u\"", metadata_store.songtime_in_milliseconds);
+    case 'astm': {
+        uint32_t ui = ntohl(*(uint32_t *)data);
+        debug(2, "MH Song Time seen: \"%u\" of length %u.", ui, length);
+        if (ui != metadata_store.songtime_in_milliseconds) {
+          metadata_store.songtime_in_milliseconds = ui;
+          metadata_store.songtime_in_milliseconds_changed = 1;
+          debug(2, "MH Song Time set to: \"%u\"", metadata_store.songtime_in_milliseconds);
+        }
       }
       break;
     case 'asal':

metadata_hub.h

@@ -68,7 +68,7 @@ typedef struct metadata_bundle {
   char *cover_art_pathname;
   int cover_art_pathname_changed;
 
-  uint32_t item_id; // seems to be a track ID -- see itemid in DACP.c
+  uint64_t item_id; // seems to be a track ID -- see itemid in DACP.c
   int item_id_changed;
   int item_id_received; // important for deciding if the track information should be ignored.
 

mpris-service.c

@@ -25,6 +25,7 @@
  */
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 
 #include "config.h"
 
@@ -174,8 +175,7 @@ void mpris_metadata_watcher(struct metadata_bundle *argc, __attribute__((unused)
   // Add in the Track ID based on the 'mper' metadata if it is non-zero
   if (argc->item_id != 0) {
     char trackidstring[128];
-    snprintf(trackidstring, sizeof(trackidstring), "/org/gnome/ShairportSync/mper_%u",
-             argc->item_id);
+    snprintf(trackidstring, sizeof(trackidstring), "/org/gnome/ShairportSync/%" PRIX64 "", argc->item_id);
     GVariant *trackid = g_variant_new("o", trackidstring);
     g_variant_builder_add(dict_builder, "{sv}", "mpris:trackid", trackid);
   }