feat(meta): separate flac meta process

internal/ffmpeg/ffmpeg.go

@@ -39,11 +39,18 @@ type UpdateMetadataParams struct {
 
 	Meta common.AudioMeta // required
 
-	AlbumArt    io.Reader // optional
-	AlbumArtExt string    // required if AlbumArt is not nil
+	AlbumArt    []byte // optional
+	AlbumArtExt string // required if AlbumArt is not nil
 }
 
-func UpdateAudioMetadata(ctx context.Context, outPath string, params *UpdateMetadataParams) error {
+func UpdateMeta(ctx context.Context, outPath string, params *UpdateMetadataParams) error {
+	if params.AudioExt == ".flac" {
+		return updateMetaFlac(ctx, outPath, params)
+	} else {
+		return updateMetaFFmpeg(ctx, outPath, params)
+	}
+}
+func updateMetaFFmpeg(ctx context.Context, outPath string, params *UpdateMetadataParams) error {
 	builder := newFFmpegBuilder()
 
 	out := newOutputBuilder(outPath) // output to file
@@ -60,7 +67,7 @@ func UpdateAudioMetadata(ctx context.Context, outPath string, params *UpdateMeta
 		params.AudioExt != ".wav" /* wav doesn't support attached image */ {
 
 		// write cover to temp file
-		artPath, err := utils.WriteTempFile(params.AlbumArt, params.AlbumArtExt)
+		artPath, err := utils.WriteTempFile(bytes.NewReader(params.AlbumArt), params.AlbumArtExt)
 		if err != nil {
 			return fmt.Errorf("updateAudioMeta write temp file: %w", err)
 		}
@@ -77,6 +84,10 @@ func UpdateAudioMetadata(ctx context.Context, outPath string, params *UpdateMeta
 			out.AddOption("disposition:v", "attached_pic")
 			out.AddMetadata("s:v", "title", "Album cover")
 			out.AddMetadata("s:v", "comment", "Cover (front)")
+		case ".mp3":
+			out.AddOption("codec:v", "mjpeg")
+			out.AddMetadata("s:v", "title", "Album cover")
+			out.AddMetadata("s:v", "comment", "Cover (front)")
 		default: // other formats use default behavior
 		}
 	}
@@ -98,6 +109,11 @@ func UpdateAudioMetadata(ctx context.Context, outPath string, params *UpdateMeta
 		out.AddMetadata("", "artist", strings.Join(artists, " / "))
 	}
 
+	if params.AudioExt == ".mp3" {
+		out.AddOption("write_id3v1", "true")
+		out.AddOption("id3v2_version", "3")
+	}
+
 	// execute ffmpeg
 	cmd := builder.Command(ctx)
 

internal/ffmpeg/meta_flac.go

@@ -0,0 +1,90 @@
+package ffmpeg
+
+import (
+	"context"
+	"mime"
+	"strings"
+
+	"github.com/go-flac/flacpicture"
+	"github.com/go-flac/flacvorbis"
+	"github.com/go-flac/go-flac"
+	"golang.org/x/exp/slices"
+)
+
+func updateMetaFlac(_ context.Context, outPath string, m *UpdateMetadataParams) error {
+	f, err := flac.ParseFile(m.Audio)
+	if err != nil {
+		return err
+	}
+
+	// generate comment block
+	comment := flacvorbis.MetaDataBlockVorbisComment{Vendor: "unlock-music.dev"}
+
+	// add metadata
+	title := m.Meta.GetTitle()
+	if title != "" {
+		_ = comment.Add(flacvorbis.FIELD_TITLE, title)
+	}
+
+	album := m.Meta.GetAlbum()
+	if album != "" {
+		_ = comment.Add(flacvorbis.FIELD_ALBUM, album)
+	}
+
+	artists := m.Meta.GetArtists()
+	for _, artist := range artists {
+		_ = comment.Add(flacvorbis.FIELD_ARTIST, artist)
+	}
+
+	existCommentIdx := slices.IndexFunc(f.Meta, func(b *flac.MetaDataBlock) bool {
+		return b.Type == flac.VorbisComment
+	})
+	if existCommentIdx >= 0 { // copy existing comment fields
+		exist, err := flacvorbis.ParseFromMetaDataBlock(*f.Meta[existCommentIdx])
+		if err != nil {
+			for _, s := range exist.Comments {
+				if strings.HasPrefix(s, flacvorbis.FIELD_TITLE+"=") && title != "" ||
+					strings.HasPrefix(s, flacvorbis.FIELD_ALBUM+"=") && album != "" ||
+					strings.HasPrefix(s, flacvorbis.FIELD_ARTIST+"=") && len(artists) != 0 {
+					continue
+				}
+				comment.Comments = append(comment.Comments, s)
+			}
+		}
+	}
+
+	// add / replace flac comment
+	cmtBlock := comment.Marshal()
+	if existCommentIdx < 0 {
+		f.Meta = append(f.Meta, &cmtBlock)
+	} else {
+		f.Meta[existCommentIdx] = &cmtBlock
+	}
+
+	if m.AlbumArt != nil {
+
+		cover, err := flacpicture.NewFromImageData(
+			flacpicture.PictureTypeFrontCover,
+			"Front cover",
+			m.AlbumArt,
+			mime.TypeByExtension(m.AlbumArtExt),
+		)
+		if err != nil {
+			return err
+		}
+		coverBlock := cover.Marshal()
+		f.Meta = append(f.Meta, &coverBlock)
+
+		// add / replace flac cover
+		coverIdx := slices.IndexFunc(f.Meta, func(b *flac.MetaDataBlock) bool {
+			return b.Type == flac.Picture
+		})
+		if coverIdx < 0 {
+			f.Meta = append(f.Meta, &coverBlock)
+		} else {
+			f.Meta[coverIdx] = &coverBlock
+		}
+	}
+
+	return f.Save(outPath)
+}