added isrc meta tag

internal/metadata/metadata.go

@@ -18,6 +18,7 @@ type Metadata struct {
 	Track       int
 	TotalTracks int
 	Comment     *string
+	ISRC        *string
 }
 
 func ReadAudioTags(filePath string) (*Metadata, error) {

internal/metadata/vobis.go

@@ -70,12 +70,22 @@ func readVorbisMetadata(file string) (*Metadata, error) {
 		comment = &comments[0]
 	}
 
+	isrcs, err := cmt.Get("ISRC")
+	if err != nil {
+		return nil, err
+	}
+	var isrc *string
+	if len(isrcs) > 0 {
+		isrc = &isrcs[0]
+	}
+
 	metadata := &Metadata{
 		Title:       title,
 		Artist:      artists,
 		Album:       album,
 		AlbumArtist: albumArtists,
 		Comment:     comment,
+		ISRC:        isrc,
 	}
 
 	return metadata, nil
@@ -139,6 +149,10 @@ func createVorbisMetaBlock(m Metadata) flacvorbis.MetaDataBlockVorbisComment {
 		vorbisMeta.Add("TOTALTRACKS", strconv.Itoa(m.TotalTracks))
 	}
 
+	if m.ISRC != nil {
+		vorbisMeta.Add("ISRC", *m.ISRC)
+	}
+
 	for _, artist := range m.Artist {
 		vorbisMeta.Add(flacvorbis.FIELD_ARTIST, artist)
 		slog.Debug("Added ARTIST filed to metadata", "artist", artist)