[scan] option to use first genre on multi token genres

multiple genres are either supported by format (see flac/orbis) or are
handled by convention (see mp3) - ffmpeg presents either case as a
single string, seperated by ';' (ie "Pop;Rock")

Currently the server/db does not support multiple genres and will store
the ffmpeg string as-is which is unlikely the user intention.

Introduce 'split_genre' to take the first genre token

owntone.conf.in

@@ -171,6 +171,12 @@ library {
 	# to trigger a rescan.
 #	filescan_disable = false
 
+	# Should server use first genre found in metadata
+	# Tracks may be tagged with multiple genres, such as 'Pop' and 'Rock'.
+	# This option instructs the server to use only the first genre found
+	# (ie 'Pop' in this case) when parsing genre
+#	split_genre = false
+
 	# Should metadata from m3u playlists, e.g. artist and title in EXTINF,
 	# override the metadata we get from radio streams?
 #	m3u_overrides = false

src/conffile.c

@@ -118,6 +118,7 @@ static cfg_opt_t sec_library[] =
     CFG_BOOL("allow_modifying_stored_playlists", cfg_false, CFGF_NONE),
     CFG_STR("default_playlist_directory", NULL, CFGF_NONE),
     CFG_BOOL("clear_queue_on_stop_disable", cfg_false, CFGF_NONE),
+    CFG_BOOL("split_genre", cfg_false, CFGF_NONE),
     CFG_END()
   };
 

src/library/filescanner_ffmpeg.c

@@ -35,6 +35,7 @@
 #include "logger.h"
 #include "misc.h"
 #include "http.h"
+#include "conffile.h"
 
 /* Mapping between the metadata name(s) and the offset
  * of the equivalent metadata field in struct media_file_info */
@@ -55,6 +56,24 @@ err2str(int errnum)
   return errbuf;
 }
 
+static int
+parse_genre(struct media_file_info *mfi, char *genre_string)
+{
+  char **genre = (char**)((char *) mfi + mfi_offsetof(genre));
+  char *ptr;
+
+  *genre = strdup(genre_string);
+
+  if (cfg_getbool(cfg_getsec(cfg, "library"), "split_genre"))
+    {
+      ptr = strchr(*genre, ';');
+      if (ptr)
+        *ptr = '\0';
+    }
+
+  return 1;
+}
+
 static int
 parse_slash_separated_ints(char *string, uint32_t *firstval, uint32_t *secondval)
 {
@@ -149,7 +168,7 @@ static const struct metadata_map md_map_generic[] =
     { "author",       0, mfi_offsetof(artist),             NULL },
     { "album_artist", 0, mfi_offsetof(album_artist),       NULL },
     { "album",        0, mfi_offsetof(album),              NULL },
-    { "genre",        0, mfi_offsetof(genre),              NULL },
+    { "genre",        0, mfi_offsetof(genre),              parse_genre },
     { "composer",     0, mfi_offsetof(composer),           NULL },
     { "grouping",     0, mfi_offsetof(grouping),           NULL },
     { "orchestra",    0, mfi_offsetof(orchestra),          NULL },