.add composer and fix multiple value tag

app.go

@@ -161,6 +161,7 @@ type DownloadRequest struct {
 	SpotifyTotalDiscs    int    `json:"spotify_total_discs,omitempty"`
 	Copyright            string `json:"copyright,omitempty"`
 	Publisher            string `json:"publisher,omitempty"`
+	Composer             string `json:"composer,omitempty"`
 	PlaylistName         string `json:"playlist_name,omitempty"`
 	PlaylistOwner        string `json:"playlist_owner,omitempty"`
 	AllowFallback        bool   `json:"allow_fallback"`
@@ -384,11 +385,6 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 		spotifyURL = fmt.Sprintf("https://open.spotify.com/track/%s", req.SpotifyID)
 	}
 
-	if req.SpotifyID != "" && (req.Copyright == "" || req.Publisher == "" || req.SpotifyTotalDiscs == 0 || req.ReleaseDate == "" || req.SpotifyTotalTracks == 0 || req.SpotifyTrackNumber == 0) {
-		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-		defer cancel()
-
-		trackURL := fmt.Sprintf("https://open.spotify.com/track/%s", req.SpotifyID)
 	metadataSeparator := req.Separator
 	if metadataSeparator == "" {
 		metadataSeparator = ", "
@@ -403,6 +399,12 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 			}
 		}
 	}
+
+	if req.SpotifyID != "" && (req.Copyright == "" || req.Publisher == "" || req.Composer == "" || req.SpotifyTotalDiscs == 0 || req.ReleaseDate == "" || req.SpotifyTotalTracks == 0 || req.SpotifyTrackNumber == 0) {
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		trackURL := fmt.Sprintf("https://open.spotify.com/track/%s", req.SpotifyID)
 		trackData, err := backend.GetFilteredSpotifyData(ctx, trackURL, false, 0, metadataSeparator, nil)
 		if err == nil {
 
@@ -410,6 +412,7 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 				Track struct {
 					Copyright   string `json:"copyright"`
 					Publisher   string `json:"publisher"`
+					Composer    string `json:"composer"`
 					TotalDiscs  int    `json:"total_discs"`
 					TotalTracks int    `json:"total_tracks"`
 					TrackNumber int    `json:"track_number"`
@@ -425,6 +428,9 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 					if req.Publisher == "" && trackResp.Track.Publisher != "" {
 						req.Publisher = trackResp.Track.Publisher
 					}
+					if req.Composer == "" && trackResp.Track.Composer != "" {
+						req.Composer = trackResp.Track.Composer
+					}
 					if req.SpotifyTotalDiscs == 0 && trackResp.Track.TotalDiscs > 0 {
 						req.SpotifyTotalDiscs = trackResp.Track.TotalDiscs
 					}
@@ -500,25 +506,25 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 
 		downloader := backend.NewAmazonDownloader()
 		if req.ServiceURL != "" {
-			filename, err = downloader.DownloadByURL(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.PlaylistName, req.PlaylistOwner, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.CoverURL, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.EmbedMaxQualityCover, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+			filename, err = downloader.DownloadByURL(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.PlaylistName, req.PlaylistOwner, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.CoverURL, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.EmbedMaxQualityCover, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 		} else {
-			filename, err = downloader.DownloadBySpotifyID(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.PlaylistName, req.PlaylistOwner, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.CoverURL, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.EmbedMaxQualityCover, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+			filename, err = downloader.DownloadBySpotifyID(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.PlaylistName, req.PlaylistOwner, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.CoverURL, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.EmbedMaxQualityCover, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 		}
 
 	case "tidal":
 		if req.ApiURL == "" || req.ApiURL == "auto" {
 			downloader := backend.NewTidalDownloader("")
 			if req.ServiceURL != "" {
-				filename, err = downloader.DownloadByURLWithFallback(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+				filename, err = downloader.DownloadByURLWithFallback(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 			} else {
-				filename, err = downloader.Download(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+				filename, err = downloader.Download(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 			}
 		} else {
 			downloader := backend.NewTidalDownloader(req.ApiURL)
 			if req.ServiceURL != "" {
-				filename, err = downloader.DownloadByURL(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+				filename, err = downloader.DownloadByURL(req.ServiceURL, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 			} else {
-				filename, err = downloader.Download(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+				filename, err = downloader.Download(req.SpotifyID, req.OutputDir, req.AudioFormat, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 			}
 		}
 
@@ -531,7 +537,7 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 		if quality == "" {
 			quality = "6"
 		}
-		filename, err = downloader.DownloadTrackWithISRC(isrc, req.OutputDir, quality, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
+		filename, err = downloader.DownloadTrackWithISRC(isrc, req.OutputDir, quality, req.FilenameFormat, req.TrackNumber, req.Position, req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, req.UseAlbumTrackNumber, req.CoverURL, req.EmbedMaxQualityCover, req.SpotifyTrackNumber, req.SpotifyDiscNumber, req.SpotifyTotalTracks, req.SpotifyTotalDiscs, req.Copyright, req.Publisher, req.Composer, metadataSeparator, spotifyURL, req.AllowFallback, req.UseFirstArtistOnly, req.UseSingleGenre, req.EmbedGenre)
 
 	default:
 		return DownloadResponse{

backend/amazon.go

@@ -204,7 +204,7 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir, quality str
 	return a.DownloadFromAfkarXYZ(amazonURL, outputDir, quality)
 }
 
-func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, quality, filenameFormat, playlistName, playlistOwner string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, quality, filenameFormat, playlistName, playlistOwner string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 
 	if outputDir != "." {
 		if err := os.MkdirAll(outputDir, 0755); err != nil {
@@ -390,6 +390,8 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, quality, filename
 		Comment:     spotifyURL,
 		Copyright:   spotifyCopyright,
 		Publisher:   spotifyPublisher,
+		Composer:    spotifyComposer,
+		Separator:   metadataSeparator,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 		ISRC:        isrc,
 		Genre:       mbMeta.Genre,
@@ -418,7 +420,7 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, quality, filename
 	return filePath, nil
 }
 
-func (a *AmazonDownloader) DownloadBySpotifyID(spotifyTrackID, outputDir, quality, filenameFormat, playlistName, playlistOwner string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string,
+func (a *AmazonDownloader) DownloadBySpotifyID(spotifyTrackID, outputDir, quality, filenameFormat, playlistName, playlistOwner string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string,
 	useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool,
 ) (string, error) {
 
@@ -427,5 +429,5 @@ func (a *AmazonDownloader) DownloadBySpotifyID(spotifyTrackID, outputDir, qualit
 		return "", err
 	}
 
-	return a.DownloadByURL(amazonURL, outputDir, quality, filenameFormat, playlistName, playlistOwner, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, embedMaxQualityCover, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyURL, useFirstArtistOnly, useSingleGenre, embedGenre)
+	return a.DownloadByURL(amazonURL, outputDir, quality, filenameFormat, playlistName, playlistOwner, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, embedMaxQualityCover, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL, useFirstArtistOnly, useSingleGenre, embedGenre)
 }

backend/artist_format.go

@@ -0,0 +1,90 @@
+package backend
+
+import "strings"
+
+func normalizeArtistSeparator(separator string) string {
+	separator = strings.TrimSpace(separator)
+	if separator == "," || separator == ";" {
+		return separator
+	}
+	return ""
+}
+
+func splitArtistSegment(segment string, separator string) []string {
+	segment = strings.TrimSpace(segment)
+	if segment == "" {
+		return nil
+	}
+
+	if strings.Contains(segment, "|||SEP|||") {
+		return strings.Split(segment, "|||SEP|||")
+	}
+
+	parts := []string{segment}
+
+	if separator = normalizeArtistSeparator(separator); separator != "" {
+		var separated []string
+		for _, part := range parts {
+			for _, item := range strings.Split(part, separator) {
+				separated = append(separated, item)
+			}
+		}
+		parts = separated
+	} else if strings.Contains(segment, ";") {
+		var separated []string
+		for _, part := range parts {
+			for _, item := range strings.Split(part, ";") {
+				separated = append(separated, item)
+			}
+		}
+		parts = separated
+	}
+
+	return parts
+}
+
+func SplitArtistCredits(artistStr, separator string) []string {
+	rawParts := splitArtistSegment(artistStr, separator)
+	if len(rawParts) == 0 {
+		return nil
+	}
+
+	seen := make(map[string]struct{}, len(rawParts))
+	result := make([]string, 0, len(rawParts))
+	for _, part := range rawParts {
+		part = strings.TrimSpace(part)
+		if part == "" {
+			continue
+		}
+		if _, exists := seen[part]; exists {
+			continue
+		}
+		seen[part] = struct{}{}
+		result = append(result, part)
+	}
+
+	return result
+}
+
+func SplitMetadataValues(value, separator string) []string {
+	rawParts := splitArtistSegment(value, separator)
+	if len(rawParts) == 0 {
+		return nil
+	}
+
+	seen := make(map[string]struct{}, len(rawParts))
+	result := make([]string, 0, len(rawParts))
+	for _, part := range rawParts {
+		part = strings.TrimSpace(part)
+		if part == "" {
+			continue
+		}
+		if _, exists := seen[part]; exists {
+			continue
+		}
+		seen[part] = struct{}{}
+		result = append(result, part)
+	}
+
+	return result
+}

backend/metadata.go

@@ -21,6 +21,7 @@ type Metadata struct {
 	Artist      string
 	Album       string
 	AlbumArtist string
+	Separator   string
 	Date        string
 	ReleaseDate string
 	TrackNumber int
@@ -31,12 +32,72 @@ type Metadata struct {
 	Comment     string
 	Copyright   string
 	Publisher   string
+	Composer    string
 	Lyrics      string
 	Description string
 	ISRC        string
 	Genre       string
 }
 
+func resolveMetadataSeparator(separator string) string {
+	if normalized := normalizeArtistSeparator(separator); normalized != "" {
+		return normalized
+	}
+
+	return normalizeArtistSeparator(GetSeparator())
+}
+
+func displayMetadataSeparator(separator string) string {
+	if resolved := resolveMetadataSeparator(separator); resolved != "" {
+		return resolved + " "
+	}
+
+	return "; "
+}
+
+func addVorbisTagValues(cmt *flacvorbis.MetaDataBlockVorbisComment, key string, values []string) {
+	for _, value := range values {
+		value = strings.TrimSpace(value)
+		if value == "" {
+			continue
+		}
+
+		_ = cmt.Add(key, value)
+	}
+}
+
+func addMP3TextFrame(tag *id3v2.Tag, frameID string, value string) {
+	tag.DeleteFrames(frameID)
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return
+	}
+
+	tag.AddTextFrame(frameID, id3v2.EncodingUTF8, value)
+}
+
+func joinMultiValueText(values []string, separator string, nullSeparated bool) string {
+	cleaned := make([]string, 0, len(values))
+	for _, value := range values {
+		value = strings.TrimSpace(value)
+		if value != "" {
+			cleaned = append(cleaned, value)
+		}
+	}
+
+	if len(cleaned) == 0 {
+		return ""
+	}
+	if len(cleaned) == 1 {
+		return cleaned[0]
+	}
+	if nullSeparated {
+		return strings.Join(cleaned, "\x00")
+	}
+
+	return strings.Join(cleaned, displayMetadataSeparator(separator))
+}
+
 func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
 	f, err := flac.ParseFile(filepath)
 	if err != nil {
@@ -52,17 +113,22 @@ func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
 	}
 
 	cmt := flacvorbis.New()
+	separator := resolveMetadataSeparator(metadata.Separator)
 
 	if metadata.Title != "" {
 		_ = cmt.Add(flacvorbis.FIELD_TITLE, metadata.Title)
 	}
-	if metadata.Artist != "" {
+	if artistValues := SplitArtistCredits(metadata.Artist, separator); len(artistValues) > 0 {
+		addVorbisTagValues(cmt, flacvorbis.FIELD_ARTIST, artistValues)
+	} else if metadata.Artist != "" {
 		_ = cmt.Add(flacvorbis.FIELD_ARTIST, metadata.Artist)
 	}
 	if metadata.Album != "" {
 		_ = cmt.Add(flacvorbis.FIELD_ALBUM, metadata.Album)
 	}
-	if metadata.AlbumArtist != "" {
+	if albumArtistValues := SplitArtistCredits(metadata.AlbumArtist, separator); len(albumArtistValues) > 0 {
+		addVorbisTagValues(cmt, "ALBUMARTIST", albumArtistValues)
+	} else if metadata.AlbumArtist != "" {
 		_ = cmt.Add("ALBUMARTIST", metadata.AlbumArtist)
 	}
 	if metadata.Date != "" {
@@ -86,6 +152,11 @@ func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
 	if metadata.Publisher != "" {
 		_ = cmt.Add("PUBLISHER", metadata.Publisher)
 	}
+	if composerValues := SplitArtistCredits(metadata.Composer, separator); len(composerValues) > 0 {
+		addVorbisTagValues(cmt, "COMPOSER", composerValues)
+	} else if metadata.Composer != "" {
+		_ = cmt.Add("COMPOSER", metadata.Composer)
+	}
 	if metadata.Description != "" {
 		_ = cmt.Add("DESCRIPTION", metadata.Description)
 	}
@@ -97,7 +168,9 @@ func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
 		_ = cmt.Add("ISRC", metadata.ISRC)
 	}
 
-	if metadata.Genre != "" {
+	if genreValues := SplitMetadataValues(metadata.Genre, separator); len(genreValues) > 0 {
+		addVorbisTagValues(cmt, "GENRE", genreValues)
+	} else if metadata.Genre != "" {
 		_ = cmt.Add("GENRE", metadata.Genre)
 	}
 
@@ -901,6 +974,10 @@ func ExtractFullMetadataFromFile(filePath string) (Metadata, error) {
 			metadata.Copyright = value
 		case "publisher", "tpub", "label":
 			metadata.Publisher = value
+		case "composer", "writer", "wm/composer", "©wrt":
+			metadata.Composer = value
+		case "genre", "tcon":
+			metadata.Genre = value
 		case "url":
 			metadata.URL = value
 		case "comment", "comments":
@@ -940,15 +1017,13 @@ func embedMetadataToMP3(filePath string, metadata Metadata, coverPath string) er
 		return fmt.Errorf("failed to open MP3 file: %w", err)
 	}
 	defer tag.Close()
+	separator := resolveMetadataSeparator(metadata.Separator)
 
 	tag.DeleteFrames("TXXX")
 
 	if metadata.Title != "" {
 		tag.SetTitle(metadata.Title)
 	}
-	if metadata.Artist != "" {
-		tag.SetArtist(metadata.Artist)
-	}
 	if metadata.Album != "" {
 		tag.SetAlbum(metadata.Album)
 	}
@@ -960,10 +1035,17 @@ func embedMetadataToMP3(filePath string, metadata Metadata, coverPath string) er
 		tag.SetYear(year)
 	}
 
-	if metadata.AlbumArtist != "" {
+	artistText := joinMultiValueText(SplitArtistCredits(metadata.Artist, separator), separator, true)
-		tag.DeleteFrames("TPE2")
+	if artistText == "" {
-		tag.AddTextFrame("TPE2", id3v2.EncodingUTF8, metadata.AlbumArtist)
+		artistText = strings.TrimSpace(metadata.Artist)
 	}
+	addMP3TextFrame(tag, "TPE1", artistText)
+
+	albumArtistText := joinMultiValueText(SplitArtistCredits(metadata.AlbumArtist, separator), separator, true)
+	if albumArtistText == "" {
+		albumArtistText = strings.TrimSpace(metadata.AlbumArtist)
+	}
+	addMP3TextFrame(tag, "TPE2", albumArtistText)
 
 	if metadata.TrackNumber > 0 {
 		tag.DeleteFrames(tag.CommonID("Track number/Position in set"))
@@ -984,18 +1066,21 @@ func embedMetadataToMP3(filePath string, metadata Metadata, coverPath string) er
 	}
 
 	if metadata.Copyright != "" {
-		tag.DeleteFrames("TCOP")
+		addMP3TextFrame(tag, "TCOP", metadata.Copyright)
-		tag.AddTextFrame("TCOP", id3v2.EncodingUTF8, metadata.Copyright)
 	}
 
 	if metadata.Publisher != "" {
-		tag.DeleteFrames("TPUB")
+		addMP3TextFrame(tag, "TPUB", metadata.Publisher)
-		tag.AddTextFrame("TPUB", id3v2.EncodingUTF8, metadata.Publisher)
 	}
 
+	composerText := joinMultiValueText(SplitArtistCredits(metadata.Composer, separator), separator, true)
+	if composerText == "" {
+		composerText = strings.TrimSpace(metadata.Composer)
+	}
+	addMP3TextFrame(tag, "TCOM", composerText)
+
 	if metadata.ISRC != "" {
-		tag.DeleteFrames("TSRC")
+		addMP3TextFrame(tag, "TSRC", metadata.ISRC)
-		tag.AddTextFrame("TSRC", id3v2.EncodingUTF8, metadata.ISRC)
 	}
 
 	if comment := resolveMetadataComment(metadata); comment != "" {
@@ -1027,6 +1112,12 @@ func embedMetadataToMP3(filePath string, metadata Metadata, coverPath string) er
 		}
 	}
 
+	genreText := joinMultiValueText(SplitMetadataValues(metadata.Genre, separator), separator, true)
+	if genreText == "" {
+		genreText = strings.TrimSpace(metadata.Genre)
+	}
+	addMP3TextFrame(tag, "TCON", genreText)
+
 	if err := tag.Save(); err != nil {
 		return fmt.Errorf("failed to save MP3 tags: %w", err)
 	}
@@ -1048,6 +1139,7 @@ func embedMetadataToM4A(filePath string, metadata Metadata, coverPath string) er
 		"-i", filePath,
 		"-y",
 	}
+	separator := resolveMetadataSeparator(metadata.Separator)
 
 	if coverPath != "" && fileExists(coverPath) {
 		args = append(args, "-i", coverPath)
@@ -1059,14 +1151,22 @@ func embedMetadataToM4A(filePath string, metadata Metadata, coverPath string) er
 	if metadata.Title != "" {
 		args = append(args, "-metadata", "title="+metadata.Title)
 	}
-	if metadata.Artist != "" {
+	artistText := joinMultiValueText(SplitArtistCredits(metadata.Artist, separator), separator, false)
-		args = append(args, "-metadata", "artist="+metadata.Artist)
+	if artistText == "" {
+		artistText = strings.TrimSpace(metadata.Artist)
+	}
+	if artistText != "" {
+		args = append(args, "-metadata", "artist="+artistText)
 	}
 	if metadata.Album != "" {
 		args = append(args, "-metadata", "album="+metadata.Album)
 	}
-	if metadata.AlbumArtist != "" {
+	albumArtistText := joinMultiValueText(SplitArtistCredits(metadata.AlbumArtist, separator), separator, false)
-		args = append(args, "-metadata", "album_artist="+metadata.AlbumArtist)
+	if albumArtistText == "" {
+		albumArtistText = strings.TrimSpace(metadata.AlbumArtist)
+	}
+	if albumArtistText != "" {
+		args = append(args, "-metadata", "album_artist="+albumArtistText)
 	}
 	if metadata.Date != "" {
 		args = append(args, "-metadata", "date="+metadata.Date)
@@ -1091,9 +1191,23 @@ func embedMetadataToM4A(filePath string, metadata Metadata, coverPath string) er
 	if metadata.Publisher != "" {
 		args = append(args, "-metadata", "publisher="+metadata.Publisher)
 	}
+	composerText := joinMultiValueText(SplitArtistCredits(metadata.Composer, separator), separator, false)
+	if composerText == "" {
+		composerText = strings.TrimSpace(metadata.Composer)
+	}
+	if composerText != "" {
+		args = append(args, "-metadata", "composer="+composerText)
+	}
 	if metadata.ISRC != "" {
 		args = append(args, "-metadata", "isrc="+metadata.ISRC)
 	}
+	genreText := joinMultiValueText(SplitMetadataValues(metadata.Genre, separator), separator, false)
+	if genreText == "" {
+		genreText = strings.TrimSpace(metadata.Genre)
+	}
+	if genreText != "" {
+		args = append(args, "-metadata", "genre="+genreText)
+	}
 	if comment := resolveMetadataComment(metadata); comment != "" {
 		args = append(args, "-metadata", "comment="+comment)
 	}

backend/qobuz.go

@@ -381,7 +381,7 @@ func buildQobuzFilename(title, artist, album, albumArtist, releaseDate string, t
 	return filename + ".flac"
 }
 
-func (q *QobuzDownloader) DownloadTrack(spotifyID, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (q *QobuzDownloader) DownloadTrack(spotifyID, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 	var isrc string
 	if spotifyID != "" {
 		linkClient := NewSongLinkClient()
@@ -394,10 +394,10 @@ func (q *QobuzDownloader) DownloadTrack(spotifyID, outputDir, quality, filenameF
 		return "", fmt.Errorf("spotify ID is required for Qobuz download")
 	}
 
-	return q.DownloadTrackWithISRC(isrc, outputDir, quality, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, useAlbumTrackNumber, spotifyCoverURL, embedMaxQualityCover, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyURL, allowFallback, useFirstArtistOnly, useSingleGenre, embedGenre)
+	return q.DownloadTrackWithISRC(isrc, outputDir, quality, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, useAlbumTrackNumber, spotifyCoverURL, embedMaxQualityCover, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL, allowFallback, useFirstArtistOnly, useSingleGenre, embedGenre)
 }
 
-func (q *QobuzDownloader) DownloadTrackWithISRC(isrc, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (q *QobuzDownloader) DownloadTrackWithISRC(isrc, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 	fmt.Printf("Fetching track info for ISRC: %s\n", isrc)
 
 	metaChan := make(chan Metadata, 1)
@@ -522,6 +522,8 @@ func (q *QobuzDownloader) DownloadTrackWithISRC(isrc, outputDir, quality, filena
 		Comment:     spotifyURL,
 		Copyright:   spotifyCopyright,
 		Publisher:   spotifyPublisher,
+		Composer:    spotifyComposer,
+		Separator:   metadataSeparator,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 		ISRC:        isrc,
 		Genre:       mbMeta.Genre,

backend/spotify_metadata.go

@@ -53,6 +53,7 @@ type TrackMetadata struct {
 	ArtistsData []ArtistSimple `json:"artists_data,omitempty"`
 	Copyright   string         `json:"copyright,omitempty"`
 	Publisher   string         `json:"publisher,omitempty"`
+	Composer    string         `json:"composer,omitempty"`
 	Plays       string         `json:"plays,omitempty"`
 	PreviewURL  string         `json:"preview_url,omitempty"`
 	IsExplicit  bool           `json:"is_explicit,omitempty"`
@@ -193,6 +194,7 @@ type apiTrackResponse struct {
 	Disc      int      `json:"disc"`
 	Discs     int      `json:"discs"`
 	Copyright string   `json:"copyright"`
+	Composer  string   `json:"composer,omitempty"`
 	Plays     string   `json:"plays"`
 	Album     struct {
 		ID       string `json:"id"`
@@ -496,6 +498,10 @@ func (c *SpotifyMetadataClient) fetchTrack(ctx context.Context, trackID string)
 	}
 
 	filteredData := FilterTrack(data, c.Separator, albumFetchData)
+	composer, composerErr := c.fetchTrackComposerWithClient(ctx, client, trackID)
+	if composerErr == nil && composer != "" {
+		filteredData["composer"] = composer
+	}
 
 	jsonData, err := json.Marshal(filteredData)
 	if err != nil {
@@ -510,6 +516,89 @@ func (c *SpotifyMetadataClient) fetchTrack(ctx context.Context, trackID string)
 	return &result, nil
 }
 
+func collectTrackCreditNamesByRole(items []interface{}, role string) []string {
+	role = strings.TrimSpace(role)
+	if role == "" || len(items) == 0 {
+		return nil
+	}
+
+	seen := make(map[string]struct{}, len(items))
+	names := make([]string, 0, len(items))
+	for _, item := range items {
+		itemMap, ok := item.(map[string]interface{})
+		if !ok {
+			continue
+		}
+
+		if !strings.EqualFold(strings.TrimSpace(getString(itemMap, "role")), role) {
+			continue
+		}
+
+		name := strings.TrimSpace(getString(itemMap, "name"))
+		if name == "" {
+			continue
+		}
+		if _, exists := seen[name]; exists {
+			continue
+		}
+
+		seen[name] = struct{}{}
+		names = append(names, name)
+	}
+
+	return names
+}
+
+func (c *SpotifyMetadataClient) fetchTrackComposerWithClient(ctx context.Context, client *SpotifyClient, trackID string) (string, error) {
+	_ = ctx
+
+	payload := map[string]interface{}{
+		"variables": map[string]interface{}{
+			"trackUri":           fmt.Sprintf("spotify:track:%s", trackID),
+			"contributorsLimit":  100,
+			"contributorsOffset": 0,
+		},
+		"operationName": "queryTrackCreditsModal",
+		"extensions": map[string]interface{}{
+			"persistedQuery": map[string]interface{}{
+				"version":    1,
+				"sha256Hash": "e2ca40d46cf1fde36562261ccec754f23fb31b561877252e9fe0d6834aabb84b",
+			},
+		},
+	}
+
+	data, err := client.Query(payload)
+	if err != nil {
+		return "", fmt.Errorf("failed to query track credits: %w", err)
+	}
+
+	creditItems := getSlice(
+		getMap(
+			getMap(
+				getMap(
+					getMap(data, "data"),
+					"trackUnion",
+				),
+				"creditsTrait",
+			),
+			"contributors",
+		),
+		"items",
+	)
+
+	composerNames := collectTrackCreditNamesByRole(creditItems, "Composer")
+	if len(composerNames) == 0 {
+		return "", nil
+	}
+
+	separator := strings.TrimSpace(c.Separator)
+	if separator == "" {
+		separator = ", "
+	}
+
+	return strings.Join(composerNames, separator), nil
+}
+
 func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID string, callback MetadataCallback) (*apiAlbumResponse, error) {
 	client := NewSpotifyClient()
 	if err := client.Initialize(); err != nil {
@@ -963,6 +1052,7 @@ func (c *SpotifyMetadataClient) formatTrackData(raw *apiTrackResponse) TrackResp
 		ArtistsData: artistsData,
 		Copyright:   raw.Copyright,
 		Publisher:   raw.Album.Label,
+		Composer:    raw.Composer,
 		Plays:       raw.Plays,
 		IsExplicit:  raw.IsExplicit,
 	}

backend/tidal.go

@@ -416,7 +416,7 @@ func (t *TidalDownloader) DownloadFromManifest(manifestB64, outputPath string) e
 	return nil
 }
 
-func (t *TidalDownloader) DownloadByURL(tidalURL, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (t *TidalDownloader) DownloadByURL(tidalURL, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 	if outputDir != "." {
 		if err := os.MkdirAll(outputDir, 0755); err != nil {
 			return "", fmt.Errorf("directory error: %w", err)
@@ -554,6 +554,8 @@ func (t *TidalDownloader) DownloadByURL(tidalURL, outputDir, quality, filenameFo
 		Comment:     spotifyURL,
 		Copyright:   spotifyCopyright,
 		Publisher:   spotifyPublisher,
+		Composer:    spotifyComposer,
+		Separator:   metadataSeparator,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 		ISRC:        isrc,
 		Genre:       mbMeta.Genre,
@@ -570,7 +572,7 @@ func (t *TidalDownloader) DownloadByURL(tidalURL, outputDir, quality, filenameFo
 	return outputFilename, nil
 }
 
-func (t *TidalDownloader) DownloadByURLWithFallback(tidalURL, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (t *TidalDownloader) DownloadByURLWithFallback(tidalURL, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 	apis, err := t.GetAvailableAPIs()
 	if err != nil {
 		return "", fmt.Errorf("no APIs available for fallback: %w", err)
@@ -714,6 +716,8 @@ func (t *TidalDownloader) DownloadByURLWithFallback(tidalURL, outputDir, quality
 		Comment:     spotifyURL,
 		Copyright:   spotifyCopyright,
 		Publisher:   spotifyPublisher,
+		Composer:    spotifyComposer,
+		Separator:   metadataSeparator,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 		ISRC:        isrc,
 		Genre:       mbMeta.Genre,
@@ -730,14 +734,14 @@ func (t *TidalDownloader) DownloadByURLWithFallback(tidalURL, outputDir, quality
 	return outputFilename, nil
 }
 
-func (t *TidalDownloader) Download(spotifyTrackID, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
+func (t *TidalDownloader) Download(spotifyTrackID, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL string, allowFallback bool, useFirstArtistOnly bool, useSingleGenre bool, embedGenre bool) (string, error) {
 
 	tidalURL, err := t.GetTidalURLFromSpotify(spotifyTrackID)
 	if err != nil {
 		return "", fmt.Errorf("songlink couldn't find Tidal URL: %w", err)
 	}
 
-	return t.DownloadByURLWithFallback(tidalURL, outputDir, quality, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, useAlbumTrackNumber, spotifyCoverURL, embedMaxQualityCover, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyURL, allowFallback, useFirstArtistOnly, useSingleGenre, embedGenre)
+	return t.DownloadByURLWithFallback(tidalURL, outputDir, quality, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, useAlbumTrackNumber, spotifyCoverURL, embedMaxQualityCover, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyComposer, metadataSeparator, spotifyURL, allowFallback, useFirstArtistOnly, useSingleGenre, embedGenre)
 }
 
 type SegmentTemplate struct {