feat: format multi-artist credits

This commit is contained in:
2026-07-11 04:44:54 +02:00
parent d2fa098d69
commit 3413de1daa
8 changed files with 349 additions and 26 deletions
+149
View File
@@ -1,6 +1,7 @@
package tag
import (
"encoding/binary"
"fmt"
"os"
"os/exec"
@@ -13,6 +14,7 @@ type Metadata struct {
Title string
Album string
Artist string
Artists []string
AlbumArtist string
OmitDiscTags bool
TrackNumber int
@@ -71,6 +73,9 @@ func (t *Tagger) TagFLAC(path string, meta Metadata, coverPath string) error {
_ = os.Remove(tmpPath)
return err
}
if err = applyMultiValueFLACTags(path, meta); err != nil {
return err
}
return nil
}
@@ -195,6 +200,150 @@ func toTags(meta Metadata) map[string]string {
return tags
}
func applyMultiValueFLACTags(path string, meta Metadata) error {
if strings.ToLower(strings.TrimPrefix(filepath.Ext(path), ".")) != "flac" || len(meta.Artists) == 0 {
return nil
}
st, err := os.Stat(path)
if err != nil {
return err
}
data, err := os.ReadFile(path)
if err != nil {
return err
}
updated, err := replaceFLACVorbisComments(data, "ARTISTS", meta.Artists)
if err != nil {
return err
}
if updated == nil {
return nil
}
return os.WriteFile(path, updated, st.Mode())
}
type flacMetadataBlock struct {
isLast bool
blockType byte
data []byte
}
func replaceFLACVorbisComments(data []byte, key string, values []string) ([]byte, error) {
if len(data) < 4 || string(data[:4]) != "fLaC" {
return nil, fmt.Errorf("not a FLAC file")
}
blocks := []flacMetadataBlock{}
pos := 4
vorbisIndex := -1
for {
if pos+4 > len(data) {
return nil, fmt.Errorf("truncated FLAC metadata header")
}
header := data[pos]
blockType := header & 0x7f
length := int(data[pos+1])<<16 | int(data[pos+2])<<8 | int(data[pos+3])
pos += 4
if pos+length > len(data) {
return nil, fmt.Errorf("truncated FLAC metadata block")
}
if blockType == 4 {
vorbisIndex = len(blocks)
}
blocks = append(blocks, flacMetadataBlock{isLast: header&0x80 != 0, blockType: blockType, data: data[pos : pos+length]})
pos += length
if header&0x80 != 0 {
break
}
}
if vorbisIndex < 0 {
return nil, nil
}
commentBlock, err := replaceVorbisCommentValues(blocks[vorbisIndex].data, key, values)
if err != nil {
return nil, err
}
blocks[vorbisIndex].data = commentBlock
out := make([]byte, 0, len(data)+len(commentBlock)-len(blocks[vorbisIndex].data))
out = append(out, data[:4]...)
for _, block := range blocks {
if len(block.data) > 0xffffff {
return nil, fmt.Errorf("FLAC metadata block too large")
}
header := block.blockType
if block.isLast {
header |= 0x80
}
out = append(out, header, byte(len(block.data)>>16), byte(len(block.data)>>8), byte(len(block.data)))
out = append(out, block.data...)
}
out = append(out, data[pos:]...)
return out, nil
}
func replaceVorbisCommentValues(data []byte, key string, values []string) ([]byte, error) {
if len(data) < 8 {
return nil, fmt.Errorf("truncated Vorbis comment block")
}
pos := 0
vendorLength := int(binary.LittleEndian.Uint32(data[pos:]))
pos += 4
if pos+vendorLength+4 > len(data) {
return nil, fmt.Errorf("truncated Vorbis vendor string")
}
vendor := data[pos : pos+vendorLength]
pos += vendorLength
commentCount := int(binary.LittleEndian.Uint32(data[pos:]))
pos += 4
comments := make([][]byte, 0, commentCount+len(values))
for i := 0; i < commentCount; i++ {
if pos+4 > len(data) {
return nil, fmt.Errorf("truncated Vorbis comment length")
}
commentLength := int(binary.LittleEndian.Uint32(data[pos:]))
pos += 4
if pos+commentLength > len(data) {
return nil, fmt.Errorf("truncated Vorbis comment")
}
comment := data[pos : pos+commentLength]
pos += commentLength
if !vorbisCommentKeyEqual(comment, key) {
comments = append(comments, comment)
}
}
for _, value := range values {
value = strings.TrimSpace(value)
if value != "" {
comments = append(comments, []byte(key+"="+value))
}
}
out := make([]byte, 0, len(data))
out = appendUint32LE(out, uint32(len(vendor)))
out = append(out, vendor...)
out = appendUint32LE(out, uint32(len(comments)))
for _, comment := range comments {
out = appendUint32LE(out, uint32(len(comment)))
out = append(out, comment...)
}
return out, nil
}
func vorbisCommentKeyEqual(comment []byte, key string) bool {
idx := strings.IndexByte(string(comment), '=')
if idx < 0 {
return false
}
return strings.EqualFold(string(comment[:idx]), key)
}
func appendUint32LE(out []byte, v uint32) []byte {
return append(out, byte(v), byte(v>>8), byte(v>>16), byte(v>>24))
}
func normalizeCopyright(in string) string {
out := strings.ReplaceAll(in, "(c)", "©")
out = strings.ReplaceAll(out, "(C)", "©")
+97
View File
@@ -1,6 +1,7 @@
package tag
import (
"encoding/binary"
"os"
"path/filepath"
"testing"
@@ -64,6 +65,102 @@ func TestToTagsTotalsAndSourceFields(t *testing.T) {
}
}
func TestToTagsArtistList(t *testing.T) {
tags := toTags(Metadata{Artist: "A, B & C", Artists: []string{"A", "B", "C"}})
if tags["artist"] != "A, B & C" {
t.Fatalf("artist tags = %+v", tags)
}
if _, ok := tags["ARTISTS"]; ok {
t.Fatalf("ARTISTS should be written as repeated FLAC comments, got %+v", tags)
}
}
func TestReplaceVorbisCommentValuesWritesRepeatedTags(t *testing.T) {
block := vorbisCommentBlock("vendor", []string{
"ARTIST=A, B & C",
"ARTISTS=A;B;C",
"TITLE=Song",
})
updated, err := replaceVorbisCommentValues(block, "ARTISTS", []string{"A", "B", "C"})
if err != nil {
t.Fatalf("replaceVorbisCommentValues() error = %v", err)
}
comments := readVorbisComments(t, updated)
want := []string{"ARTIST=A, B & C", "TITLE=Song", "ARTISTS=A", "ARTISTS=B", "ARTISTS=C"}
if len(comments) != len(want) {
t.Fatalf("comments=%#v want %#v", comments, want)
}
for i := range want {
if comments[i] != want[i] {
t.Fatalf("comments=%#v want %#v", comments, want)
}
}
}
func TestReplaceFLACVorbisComments(t *testing.T) {
vorbis := vorbisCommentBlock("vendor", []string{"ARTISTS=A;B", "TITLE=Song"})
flac := append([]byte("fLaC"), flacBlockHeader(true, 4, len(vorbis))...)
flac = append(flac, vorbis...)
flac = append(flac, []byte("audio")...)
updated, err := replaceFLACVorbisComments(flac, "ARTISTS", []string{"A", "B"})
if err != nil {
t.Fatalf("replaceFLACVorbisComments() error = %v", err)
}
if string(updated[len(updated)-5:]) != "audio" {
t.Fatalf("audio payload not preserved")
}
length := int(updated[5])<<16 | int(updated[6])<<8 | int(updated[7])
comments := readVorbisComments(t, updated[8:8+length])
want := []string{"TITLE=Song", "ARTISTS=A", "ARTISTS=B"}
if len(comments) != len(want) {
t.Fatalf("comments=%#v want %#v", comments, want)
}
for i := range want {
if comments[i] != want[i] {
t.Fatalf("comments=%#v want %#v", comments, want)
}
}
}
func vorbisCommentBlock(vendor string, comments []string) []byte {
out := []byte{}
out = appendUint32LE(out, uint32(len(vendor)))
out = append(out, vendor...)
out = appendUint32LE(out, uint32(len(comments)))
for _, comment := range comments {
out = appendUint32LE(out, uint32(len(comment)))
out = append(out, comment...)
}
return out
}
func flacBlockHeader(last bool, blockType byte, length int) []byte {
header := blockType
if last {
header |= 0x80
}
return []byte{header, byte(length >> 16), byte(length >> 8), byte(length)}
}
func readVorbisComments(t *testing.T, block []byte) []string {
t.Helper()
pos := 0
vendorLength := int(binary.LittleEndian.Uint32(block[pos:]))
pos += 4 + vendorLength
count := int(binary.LittleEndian.Uint32(block[pos:]))
pos += 4
comments := make([]string, 0, count)
for i := 0; i < count; i++ {
length := int(binary.LittleEndian.Uint32(block[pos:]))
pos += 4
comments = append(comments, string(block[pos:pos+length]))
pos += length
}
return comments
}
func TestBuildFFmpegArgsWithCover(t *testing.T) {
tmp := t.TempDir()
cover := filepath.Join(tmp, "cover.jpg")