Add titleSort tag

doc/protocol.rst

@@ -283,6 +283,7 @@ The following tags are supported by :program:`MPD`:
 * **albumartist**: on multi-artist albums, this is the artist name which shall be used for the whole album. The exact meaning of this tag is not well-defined.
 * **albumartistsort**: same as albumartist, but for sorting.
 * **title**: the song title.
+* **titlesort**:  same as title, but for sorting.
 * **track**: the decimal track number within the album.
 * **name**: a name for this song. This is not the song title. The exact meaning of this tag is not well-defined. It is often used by badly configured internet radio stations with broken tags to squeeze both the artist name and the song title in one tag.
 * **genre**: the music genre.

src/decoder/plugins/FfmpegMetaData.cxx

@@ -40,11 +40,13 @@ static constexpr struct tag_table ffmpeg_tags[] = {
 	/* from libavformat/id3v2.c */
 	{ "album-sort", TAG_ALBUM_SORT },
 	{ "artist-sort", TAG_ARTIST_SORT },
+	{ "title-sort", TAG_TITLE_SORT},
 
 	/* from libavformat/mov.c */
 	{ "sort_album_artist", TAG_ALBUM_ARTIST_SORT },
 	{ "sort_album", TAG_ALBUM_SORT },
 	{ "sort_artist", TAG_ARTIST_SORT },
+	{ "sort_name", TAG_TITLE_SORT },
 
 	/* sentinel */
 	{ nullptr, TAG_NUM_OF_ITEM_TYPES }

src/tag/Id3Scan.cxx

@@ -55,6 +55,10 @@
 #define ID3_FRAME_ALBUM_ARTIST "TPE2"
 #endif
 
+#ifndef ID3_FRAME_TITLE_SORT
+#define ID3_FRAME_TITLE_SORT "TSOT"
+#endif
+
 #ifndef ID3_FRAME_ORIGINAL_RELEASE_DATE
 #define ID3_FRAME_ORIGINAL_RELEASE_DATE "TDOR"
 #endif
@@ -352,6 +356,7 @@ scan_id3_tag(const struct id3_tag *tag, TagHandler &handler) noexcept
 	tag_id3_import_text(tag, ID3_FRAME_LABEL, TAG_LABEL,
 			    handler);
 	tag_id3_import_text(tag, ID3_FRAME_MOOD, TAG_MOOD, handler);
+	tag_id3_import_text(tag, ID3_FRAME_TITLE_SORT, TAG_TITLE_SORT, handler);
 
 	tag_id3_import_musicbrainz(tag, handler);
 	tag_id3_import_ufid(tag, handler);

src/tag/Names.c

@@ -27,6 +27,7 @@ const char *const tag_item_names[TAG_NUM_OF_ITEM_TYPES] = {
 	[TAG_ALBUM_ARTIST] = "AlbumArtist",
 	[TAG_ALBUM_ARTIST_SORT] = "AlbumArtistSort",
 	[TAG_TITLE] = "Title",
+	[TAG_TITLE_SORT] = "TitleSort",
 	[TAG_TRACK] = "Track",
 	[TAG_NAME] = "Name",
 	[TAG_GENRE] = "Genre",

src/tag/Type.h

@@ -42,6 +42,7 @@ enum TagType
 	TAG_ALBUM_ARTIST,
 	TAG_ALBUM_ARTIST_SORT,
 	TAG_TITLE,
+	TAG_TITLE_SORT,
 	TAG_TRACK,
 	TAG_NAME,
 	TAG_GENRE,