Add support for these widely-used iTunes metadata fields: Album Artist,

Grouping, and Lyrics.

Originally committed as revision 21010 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/movenc.c

@@ -1434,6 +1434,7 @@ static int mov_write_ilst_tag(ByteIOContext *pb, MOVMuxContext *mov,
     put_tag(pb, "ilst");
     mov_write_string_metadata(s, pb, "\251nam", "title"    , 1);
     mov_write_string_metadata(s, pb, "\251ART", "author"   , 1);
+    mov_write_string_metadata(s, pb, "aART", "album_artist", 1);
     mov_write_string_metadata(s, pb, "\251wrt", "composer" , 1);
     mov_write_string_metadata(s, pb, "\251alb", "album"    , 1);
     mov_write_string_metadata(s, pb, "\251day", "year"     , 1);
@@ -1441,6 +1442,8 @@ static int mov_write_ilst_tag(ByteIOContext *pb, MOVMuxContext *mov,
     mov_write_string_metadata(s, pb, "\251cmt", "comment"  , 1);
     mov_write_string_metadata(s, pb, "\251gen", "genre"    , 1);
     mov_write_string_metadata(s, pb, "\251cpy", "copyright", 1);
+    mov_write_string_metadata(s, pb, "\251grp", "grouping" , 1);
+    mov_write_string_metadata(s, pb, "\251lyr", "lyrics"   , 1);
     mov_write_string_metadata(s, pb, "desc",    "description",1);
     mov_write_string_metadata(s, pb, "ldes",    "synopsis" , 1);
     mov_write_string_metadata(s, pb, "tvsh",    "show"     , 1);