Implement ArtistSort tag

NEWS

@@ -4,7 +4,7 @@ ver 0.16 (20??/??/??)
   - added "update" idle event
   - removed the deprecated "volume" command
 * tags:
-  - added tag "AlbumArtistSort"
+  - added tags "ArtistSort", "AlbumArtistSort"
   - id3: revised "performer" tag support
 * decoders:
   - ffmpeg: support multiple tags

src/tag.c

@@ -43,6 +43,7 @@ static struct {
 
 const char *tag_item_names[TAG_NUM_OF_ITEM_TYPES] = {
 	"Artist",
+	[TAG_ARTIST_SORT] = "ArtistSort",
 	"Album",
 	"AlbumArtist",
 	[TAG_ALBUM_ARTIST_SORT] = "AlbumArtistSort",

src/tag.h

@@ -32,6 +32,7 @@
  */
 enum tag_type {
 	TAG_ITEM_ARTIST,
+	TAG_ARTIST_SORT,
 	TAG_ITEM_ALBUM,
 	TAG_ITEM_ALBUM_ARTIST,
 	TAG_ALBUM_ARTIST_SORT,

src/tag_id3.c

@@ -42,8 +42,12 @@
 #    define ID3_FRAME_DISC "TPOS"
 #  endif
 
+#ifndef ID3_FRAME_ARTIST_SORT
+#define ID3_FRAME_ARTIST_SORT "TSOP"
+#endif
+
 #ifndef ID3_FRAME_ALBUM_ARTIST_SORT
-#define ID3_FRAME_ALBUM_ARTIST_SORT "TSO2"
+#define ID3_FRAME_ALBUM_ARTIST_SORT "TSO2" /* this one is unofficial, introduced by Itunes */
 #endif
 
 #ifndef ID3_FRAME_ALBUM_ARTIST
@@ -329,6 +333,8 @@ struct tag *tag_id3_import(struct id3_tag * tag)
 	getID3Info(tag, ID3_FRAME_ARTIST, TAG_ITEM_ARTIST, ret);
 	getID3Info(tag, ID3_FRAME_ALBUM_ARTIST,
 		   TAG_ITEM_ALBUM_ARTIST, ret);
+	getID3Info(tag, ID3_FRAME_ARTIST_SORT,
+		   TAG_ARTIST_SORT, ret);
 	getID3Info(tag, ID3_FRAME_ALBUM_ARTIST_SORT,
 		   TAG_ALBUM_ARTIST_SORT, ret);
 	getID3Info(tag, ID3_FRAME_TITLE, TAG_ITEM_TITLE, ret);