[scan] Fix issue where albums get split

Regression from PR #1655. This reverts the metadata search to the method used
before the PR, so that search is done in the order set by the metadata maps.

This means the songalbumid is set by the tag with the highest precedence, not
just the first one found.

Closes #1696

src/library/filescanner_ffmpeg.c

@@ -49,6 +49,7 @@ struct metadata_map {
   int as_int;
   size_t offset;
   int (*handler_function)(struct media_file_info *, const char *);
+  int flags;
 };
 
 // Used for passing errors to DPRINTF (can't count on av_err2str being present)
@@ -196,7 +197,7 @@ static const struct metadata_map md_map_generic[] =
     { "artist-sort",  0, mfi_offsetof(artist_sort),        NULL },
     { "album-sort",   0, mfi_offsetof(album_sort),         NULL },
     { "compilation",  1, mfi_offsetof(compilation),        NULL },
-    { "lyrics",       0, mfi_offsetof(lyrics),             NULL },
+    { "lyrics",       0, mfi_offsetof(lyrics),             NULL,       AV_DICT_IGNORE_SUFFIX },
 
     // ALAC sort tags
     { "sort_name",           0, mfi_offsetof(title_sort),         NULL },
@@ -288,65 +289,56 @@ static const struct metadata_map md_map_id3[] =
     { NULL,                  0, 0,                                   NULL }
   };
 
-
 static int
-extract_metadata_from_kv(struct media_file_info *mfi, const char *key, const char *value, const struct metadata_map *md_map)
+extract_metadata_from_dict(struct media_file_info *mfi, AVDictionary *md, const struct metadata_map *md_map)
 {
+  AVDictionaryEntry *mdt;
   char **strval;
   uint32_t *intval;
+  int mdcount = 0;
   int i;
 
-  if ((value == NULL) || (strlen(value) == 0))
-    return 0;
-
-  if (strncasecmp(key, "lyrics-", sizeof("lyrics-") - 1) == 0)
-    key = "lyrics";
-
-  for (i = 0; md_map[i].key != NULL; i++)
+#if 0
+  /* Dump all the metadata reported by ffmpeg */
+  while ((mdt = av_dict_iterate(md, mdt)))
     {
-      if (strcasecmp(key, md_map[i].key) == 0)
-	break;
+      DPRINTF(E_DBG, L_SCAN, " -> %s = %s\n", mdt->key, mdt->value);
     }
+#endif
 
-  if (md_map[i].key == NULL)
-    return 0; // Not found in map
-
-  if (md_map[i].handler_function)
-    return md_map[i].handler_function(mfi, value);
-
-  if (!md_map[i].as_int)
+  for (i = 0; md_map[i].key != NULL; i++)
     {
-      strval = (char **) ((char *) mfi + md_map[i].offset);
+      mdt = av_dict_get(md, md_map[i].key, NULL, md_map[i].flags);
+      if (!mdt || !mdt->value || strlen(mdt->value) == 0)
+	continue;
 
-      if (*strval != NULL)
-	return 0;
+      if (md_map[i].handler_function)
+	{
+	  mdcount += md_map[i].handler_function(mfi, mdt->value);
+	  continue;
+	}
 
-      *strval = strdup(value);
-    }
-  else
-    {
-      intval = (uint32_t *) ((char *) mfi + md_map[i].offset);
+      if (!md_map[i].as_int)
+	{
+	  strval = (char **) ((char *) mfi + md_map[i].offset);
 
-      if (*intval != 0)
-	return 0;
+	  if (*strval != NULL)
+	    continue;
 
-      if (safe_atou32(value, intval) < 0)
-	return 0;
-    }
+	  *strval = strdup(mdt->value);
+	}
+      else
+	{
+	  intval = (uint32_t *) ((char *) mfi + md_map[i].offset);
 
-  return 1;
-}
+	  if (*intval != 0)
+	    continue;
 
-static int
-extract_metadata_from_dict(struct media_file_info *mfi, AVDictionary *md, const struct metadata_map *md_map)
-{
-  const AVDictionaryEntry *mdt = NULL;
-  int mdcount = 0;
+	  if (safe_atou32(mdt->value, intval) < 0)
+	    continue;
+	}
 
-  while ((mdt = av_dict_iterate(md, mdt)))
-    {
-//      DPRINTF(E_DBG, L_SCAN, " -> %s = %s\n", mdt->key, mdt->value);
-      mdcount += extract_metadata_from_kv(mfi, mdt->key, mdt->value, md_map);
+      mdcount++;
     }
 
   return mdcount;
@@ -355,11 +347,9 @@ extract_metadata_from_dict(struct media_file_info *mfi, AVDictionary *md, const
 static int
 extract_metadata(struct media_file_info *mfi, AVFormatContext *ctx, AVStream *audio_stream, AVStream *video_stream, const struct metadata_map *md_map)
 {
-  int mdcount;
+  int mdcount = 0;
   int ret;
 
-  mdcount = 0;
-
   if (ctx->metadata)
     {
       ret = extract_metadata_from_dict(mfi, ctx->metadata, md_map);