Extract album artist from libtags-processed files

lib/libtags/id3v2.c

@@ -19,8 +19,10 @@ v2cb(Tagctx *ctx, char *k, char *v)
 	k++;
 	if(strcmp(k, "AL") == 0 || strcmp(k, "ALB") == 0)
 		txtcb(ctx, Talbum, k-1, v);
-	else if(strcmp(k, "PE1") == 0 || strcmp(k, "PE2") == 0 || strcmp(k, "P1") == 0 || strcmp(k, "P2") == 0)
+	else if(strcmp(k, "PE1") == 0 || strcmp(k, "P1") == 0)
 		txtcb(ctx, Tartist, k-1, v);
+	else if(strcmp(k, "PE2") == 0 || strcmp(k, "P2") == 0)
+		txtcb(ctx, Talbumartist, k-1, v);
 	else if(strcmp(k, "IT2") == 0 || strcmp(k, "T2") == 0)
 		txtcb(ctx, Ttitle, k-1, v);
 	else if(strcmp(k, "YE") == 0 || strcmp(k, "YER") == 0 || strcmp(k, "DRC") == 0)

lib/libtags/tags.h

@@ -10,6 +10,7 @@ enum
 {
 	Tunknown = -1,
 	Tartist,
+	Talbumartist,
 	Talbum,
 	Ttitle,
 	Tdate, /* "2014", "2015/02/01", but the year goes first */

lib/libtags/vorbis.c

@@ -14,6 +14,8 @@ cbvorbiscomment(Tagctx *ctx, char *k, char *v){
 		txtcb(ctx, Ttitle, k, v);
 	else if(cistrcmp(k, "artist") == 0)
 		txtcb(ctx, Tartist, k, v);
+	else if(cistrcmp(k, "albumartist") == 0)
+		txtcb(ctx, Talbumartist, k, v);
 	else if(cistrcmp(k, "tracknumber") == 0)
 		txtcb(ctx, Ttrack, k, v);
 	else if(cistrcmp(k, "date") == 0)

src/database/database.cpp

@@ -55,7 +55,7 @@ static SingletonEnv<leveldb::EspEnv> sEnv;
 static const char kDbPath[] = "/.tangara-db";
 
 static const char kKeyDbVersion[] = "schema_version";
-static const uint8_t kCurrentDbVersion = 4;
+static const uint8_t kCurrentDbVersion = 5;
 
 static const char kKeyCustom[] = "U\0";
 static const char kKeyCollator[] = "collator";

src/database/tag_parser.cpp

@@ -37,6 +37,8 @@ static auto convert_tag(int tag) -> std::optional<Tag> {
       return Tag::kTitle;
     case Tartist:
       return Tag::kArtist;
+    case Talbumartist:
+      return Tag::kAlbumArtist;
     case Talbum:
       return Tag::kAlbum;
     case Ttrack: