make some ogg/vorbis/flac functions public

Co-authored-by: David Howden <dhowden@gmail.com>

.github/workflows/go.yml

@@ -0,0 +1,26 @@
+name: Go
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: "1.20"
+        cache: true
+
+    - name: Build
+      run: go build -v ./...
+
+    - name: Test
+      run: go test -v ./...

README.md

@@ -1,6 +1,5 @@
 # MP3/MP4/OGG/FLAC metadata parsing library
-[![Build Status](https://travis-ci.org/dhowden/tag.svg?branch=master)](https://travis-ci.org/dhowden/tag)
-[![GoDoc](https://godoc.org/github.com/dhowden/tag?status.svg)](https://godoc.org/github.com/dhowden/tag)
+[![GoDoc](https://pkg.go.dev/badge/github.com/dhowden/tag)](https://pkg.go.dev/github.com/dhowden/tag)
 
 This package provides MP3 (ID3v1,2.{2,3,4}) and MP4 (ACC, M4A, ALAC), OGG and FLAC metadata detection, parsing and artwork extraction.
 
@@ -47,14 +46,14 @@ type Metadata interface {
 This package also provides a metadata-invariant checksum for audio files: only the audio data is used to
 construct the checksum.
 
-[http://godoc.org/github.com/dhowden/tag#Sum](http://godoc.org/github.com/dhowden/tag#Sum)
+[https://pkg.go.dev/github.com/dhowden/tag#Sum](https://pkg.go.dev/github.com/dhowden/tag#Sum)
 
 ## Tools
 
 There are simple command-line tools which demonstrate basic tag extraction and summing:
 
 ```console
-$ go get github.com/dhowden/tag/...
+$ go install github.com/dhowden/tag/cmd/tag@latest
 $ cd $GOPATH/bin
 $ ./tag 11\ High\ Hopes.m4a
 Metadata Format: MP4

flac.go

@@ -34,12 +34,12 @@ func ReadFLACTags(r io.ReadSeeker) (Metadata, error) {
 		return nil, errors.New("expected 'fLaC'")
 	}
 
-	m := &metadataFLAC{
-		newMetadataVorbis(),
+	m := &MetadataFLAC{
+		NewMetadataVorbis(),
 	}
 
 	for {
-		last, err := m.readFLACMetadataBlock(r)
+		last, err := m.ReadFLACMetadataBlock(r)
 		if err != nil {
 			return nil, err
 		}
@@ -51,11 +51,11 @@ func ReadFLACTags(r io.ReadSeeker) (Metadata, error) {
 	return m, nil
 }
 
-type metadataFLAC struct {
-	*metadataVorbis
+type MetadataFLAC struct {
+	*MetadataVorbis
 }
 
-func (m *metadataFLAC) readFLACMetadataBlock(r io.ReadSeeker) (last bool, err error) {
+func (m *MetadataFLAC) ReadFLACMetadataBlock(r io.ReadSeeker) (last bool, err error) {
 	blockHeader, err := readBytes(r, 1)
 	if err != nil {
 		return
@@ -73,7 +73,7 @@ func (m *metadataFLAC) readFLACMetadataBlock(r io.ReadSeeker) (last bool, err er
 
 	switch blockType(blockHeader[0]) {
 	case vorbisCommentBlock:
-		err = m.readVorbisComment(r)
+		err = m.ReadVorbisComment(r)
 
 	case pictureBlock:
 		err = m.readPictureBlock(r)
@@ -84,6 +84,6 @@ func (m *metadataFLAC) readFLACMetadataBlock(r io.ReadSeeker) (last bool, err er
 	return
 }
 
-func (m *metadataFLAC) FileType() FileType {
+func (m *MetadataFLAC) FileType() FileType {
 	return FLAC
 }

go.mod

@@ -0,0 +1,7 @@
+module github.com/dhowden/tag
+
+go 1.20
+
+require github.com/dhowden/itl v0.0.0-20170329215456-9fbe21093131
+
+require github.com/dhowden/plist v0.0.0-20141002110153-5db6e0d9931a // indirect

go.sum

@@ -0,0 +1,4 @@
+github.com/dhowden/itl v0.0.0-20170329215456-9fbe21093131 h1:siEGb+iB1Ea75U7BnkYVSqSRzE6QHlXCbqEXenxRmhQ=
+github.com/dhowden/itl v0.0.0-20170329215456-9fbe21093131/go.mod h1:eVWQJVQ67aMvYhpkDwaH2Goy2vo6v8JCMfGXfQ9sPtw=
+github.com/dhowden/plist v0.0.0-20141002110153-5db6e0d9931a h1:7MucP9rMAsQRcRE1sGpvMZoTxFYZlDmfDvCH+z7H+90=
+github.com/dhowden/plist v0.0.0-20141002110153-5db6e0d9931a/go.mod h1:sLjdR6uwx3L6/Py8F+QgAfeiuY87xuYGwCDqRFrvCzw=

id3v2.go

@@ -13,6 +13,9 @@ import (
 	"strings"
 )
 
+// Genre definitions 0-79 follow the ID3 tag specification of 1999.
+// More genres have been successively introduced in later Winamp versions.
+// https://en.wikipedia.org/wiki/List_of_ID3v1_genres#Extension_by_Winamp
 var id3v2Genres = [...]string{
 	"Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk", "Grunge",
 	"Hip-Hop", "Jazz", "Metal", "New Age", "Oldies", "Other", "Pop", "R&B",
@@ -41,6 +44,14 @@ var id3v2Genres = [...]string{
 	"Heavy Metal", "Black Metal", "Crossover", "Contemporary Christian",
 	"Christian Rock ", "Merengue", "Salsa", "Thrash Metal", "Anime", "JPop",
 	"Synthpop",
+	"Christmas", "Art Rock", "Baroque", "Bhangra", "Big Beat", "Breakbeat",
+	"Chillout", "Downtempo", "Dub", "EBM", "Eclectic", "Electro",
+	"Electroclash", "Emo", "Experimental", "Garage", "Global", "IDM",
+	"Illbient", "Industro-Goth", "Jam Band", "Krautrock", "Leftfield", "Lounge",
+	"Math Rock", "New Romantic", "Nu-Breakz", "Post-Punk", "Post-Rock", "Psytrance",
+	"Shoegaze", "Space Rock", "Trop Rock", "World Music", "Neoclassical", "Audiobook",
+	"Audio Theatre", "Neue Deutsche Welle", "Podcast", "Indie Rock", "G-Funk", "Dubstep",
+	"Garage Rock", "Psybient",
 }
 
 // id3v2Header is a type which represents an ID3v2 tag header.

id3v2_test.go

@@ -141,6 +141,9 @@ func TestGenreExpension(t *testing.T) {
 		"Test (17)":    "Test Rock",
 		"(17)(93)":     "Rock Psychedelic Rock",
 		"(17)Test(93)": "Rock Test Psychedelic Rock",
+		"(175)":		"Post-Punk",
+		"(187)":		"Indie Rock",
+		"(191)":		"Psybient",
 	}
 	for g, r := range tests {
 		got := id3v2genre(g)

id3v2metadata.go

@@ -7,6 +7,7 @@ package tag
 import (
 	"strconv"
 	"strings"
+	"time"
 )
 
 type frameNames map[string][2]string
@@ -89,8 +90,18 @@ func (m metadataID3v2) Genre() string {
 }
 
 func (m metadataID3v2) Year() int {
-	year, _ := strconv.Atoi(m.getString(frames.Name("year", m.Format())))
-	return year
+	stringYear := m.getString(frames.Name("year", m.Format()))
+
+	if year, err := strconv.Atoi(stringYear); err == nil {
+		return year
+	}
+
+	date, err := time.Parse(time.DateOnly, stringYear)
+	if err != nil {
+		return 0
+	}
+
+	return date.Year()
 }
 
 func parseXofN(s string) (x, n int) {

mp4.go

@@ -45,6 +45,12 @@ var atoms = atomNames(map[string]string{
 	"disk":    "disc",
 })
 
+var means = map[string]bool{
+	"com.apple.iTunes":          true,
+	"com.mixedinkey.mixedinkey": true,
+	"com.serato.dj":             true,
+}
+
 // Detect PNG image if "implicit" class is used
 var pngHeader = []byte{137, 80, 78, 71, 13, 10, 26, 10}
 
@@ -226,7 +232,7 @@ func readAtomHeader(r io.ReadSeeker) (name string, size uint32, err error) {
 
 // Generic atom.
 // Should have 3 sub atoms : mean, name and data.
-// We check that mean is "com.apple.iTunes" and we use the subname as
+// We check that mean is "com.apple.iTunes" or others and we use the subname as
 // the name, and move to the data atom.
 // Data atom could have multiple data values, each with a header.
 // If anything goes wrong, we jump at the end of the "----" atom.
@@ -268,9 +274,10 @@ func readCustomAtom(r io.ReadSeeker, size uint32) (_ string, data []string, _ er
 		return "", nil, err
 	}
 
-	if subNames["mean"] != "com.apple.iTunes" || subNames["name"] == "" || len(data) == 0 {
+	if !means[subNames["mean"]] || subNames["name"] == "" || len(data) == 0 {
 		return "----", nil, nil
 	}
+
 	return subNames["name"], data, nil
 }
 

ogg.go

@@ -120,6 +120,9 @@ func (o *oggDemuxer) Read(r io.Reader) ([][]byte, error) {
 	var packets [][]byte
 	var p int
 	for _, s := range segmentTable {
+		if !continued && !bytes.HasPrefix(segmentsData, vorbisCommentPrefix) && !bytes.HasPrefix(segmentsData, opusTagsPrefix) {
+			return nil, fmt.Errorf("not a metadata segment")
+		}
 		packetBuf.Write(segmentsData[p : p+int(s)])
 		if s < 255 {
 			packets = append(packets, packetBuf.Bytes())
@@ -150,15 +153,15 @@ func ReadOGGTags(r io.Reader) (Metadata, error) {
 			switch {
 			case bytes.HasPrefix(b, vorbisCommentPrefix):
 				m := &metadataOGG{
-					newMetadataVorbis(),
+					NewMetadataVorbis(),
 				}
-				err = m.readVorbisComment(bytes.NewReader(b[len(vorbisCommentPrefix):]))
+				err = m.ReadVorbisComment(bytes.NewReader(b[len(vorbisCommentPrefix):]))
 				return m, err
 			case bytes.HasPrefix(b, opusTagsPrefix):
 				m := &metadataOGG{
-					newMetadataVorbis(),
+					NewMetadataVorbis(),
 				}
-				err = m.readVorbisComment(bytes.NewReader(b[len(opusTagsPrefix):]))
+				err = m.ReadVorbisComment(bytes.NewReader(b[len(opusTagsPrefix):]))
 				return m, err
 			}
 		}
@@ -166,7 +169,7 @@ func ReadOGGTags(r io.Reader) (Metadata, error) {
 }
 
 type metadataOGG struct {
-	*metadataVorbis
+	*MetadataVorbis
 }
 
 func (m *metadataOGG) FileType() FileType {

vorbis.go

@@ -15,18 +15,18 @@ import (
 	"time"
 )
 
-func newMetadataVorbis() *metadataVorbis {
-	return &metadataVorbis{
+func NewMetadataVorbis() *MetadataVorbis {
+	return &MetadataVorbis{
 		c: make(map[string]string),
 	}
 }
 
-type metadataVorbis struct {
+type MetadataVorbis struct {
 	c map[string]string // the vorbis comments
 	p *Picture
 }
 
-func (m *metadataVorbis) readVorbisComment(r io.Reader) error {
+func (m *MetadataVorbis) ReadVorbisComment(r io.Reader) error {
 	vendorLen, err := readUint32LittleEndian(r)
 	if err != nil {
 		return err
@@ -70,7 +70,7 @@ func (m *metadataVorbis) readVorbisComment(r io.Reader) error {
 	return nil
 }
 
-func (m *metadataVorbis) readPictureBlock(r io.Reader) error {
+func (m *MetadataVorbis) readPictureBlock(r io.Reader) error {
 	b, err := readInt(r, 4)
 	if err != nil {
 		return err
@@ -156,11 +156,11 @@ func parseComment(c string) (k, v string, err error) {
 	return
 }
 
-func (m *metadataVorbis) Format() Format {
+func (m *MetadataVorbis) Format() Format {
 	return VORBIS
 }
 
-func (m *metadataVorbis) Raw() map[string]interface{} {
+func (m *MetadataVorbis) Raw() map[string]interface{} {
 	raw := make(map[string]interface{}, len(m.c))
 	for k, v := range m.c {
 		raw[k] = v
@@ -168,11 +168,32 @@ func (m *metadataVorbis) Raw() map[string]interface{} {
 	return raw
 }
 
-func (m *metadataVorbis) Title() string {
+func (m *MetadataVorbis) Title() string {
 	return m.c["title"]
 }
 
-func (m *metadataVorbis) Artist() string {
+func (m *MetadataVorbis) Artist() string {
+	// ARTIST
+	// The artist generally considered responsible for the work. In popular music
+	// this is usually the performing band or singer. For classical music it would
+	// be the composer. For an audio book it would be the author of the original text.
+	return m.c["artist"]
+}
+
+func (m *MetadataVorbis) Album() string {
+	return m.c["album"]
+}
+
+func (m *MetadataVorbis) AlbumArtist() string {
+	// This field isn't actually included in the standard, though
+	// it is commonly assigned to albumartist.
+	return m.c["albumartist"]
+}
+
+func (m *MetadataVorbis) Composer() string {
+	if m.c["composer"] != "" {
+		return m.c["composer"]
+	}
 	// PERFORMER
 	// The artist(s) who performed the work. In classical music this would be the
 	// conductor, orchestra, soloists. In an audio book it would be the actor who
@@ -184,41 +205,24 @@ func (m *metadataVorbis) Artist() string {
 	return m.c["artist"]
 }
 
-func (m *metadataVorbis) Album() string {
-	return m.c["album"]
-}
-
-func (m *metadataVorbis) AlbumArtist() string {
-	// This field isn't actually included in the standard, though
-	// it is commonly assigned to albumartist.
-	return m.c["albumartist"]
-}
-
-func (m *metadataVorbis) Composer() string {
-	// ARTIST
-	// The artist generally considered responsible for the work. In popular music
-	// this is usually the performing band or singer. For classical music it would
-	// be the composer. For an audio book it would be the author of the original text.
-	if m.c["composer"] != "" {
-		return m.c["composer"]
-	}
-	if m.c["performer"] == "" {
-		return ""
-	}
-	return m.c["artist"]
-}
-
-func (m *metadataVorbis) Genre() string {
+func (m *MetadataVorbis) Genre() string {
 	return m.c["genre"]
 }
 
-func (m *metadataVorbis) Year() int {
+func (m *MetadataVorbis) Year() int {
 	var dateFormat string
 
 	// The date need to follow the international standard https://en.wikipedia.org/wiki/ISO_8601
 	// and obviously the VorbisComment standard https://wiki.xiph.org/VorbisComment#Date_and_time
 	switch len(m.c["date"]) {
 	case 0:
+		// Fallback on year tag as some files use that.
+		if len(m.c["year"]) != 0 {
+			year, err := strconv.Atoi(m.c["year"])
+			if err == nil {
+				return year
+			}
+		}
 		return 0
 	case 4:
 		dateFormat = "2006"
@@ -232,31 +236,31 @@ func (m *metadataVorbis) Year() int {
 	return t.Year()
 }
 
-func (m *metadataVorbis) Track() (int, int) {
+func (m *MetadataVorbis) Track() (int, int) {
 	x, _ := strconv.Atoi(m.c["tracknumber"])
 	// https://wiki.xiph.org/Field_names
 	n, _ := strconv.Atoi(m.c["tracktotal"])
 	return x, n
 }
 
-func (m *metadataVorbis) Disc() (int, int) {
+func (m *MetadataVorbis) Disc() (int, int) {
 	// https://wiki.xiph.org/Field_names
 	x, _ := strconv.Atoi(m.c["discnumber"])
 	n, _ := strconv.Atoi(m.c["disctotal"])
 	return x, n
 }
 
-func (m *metadataVorbis) Lyrics() string {
+func (m *MetadataVorbis) Lyrics() string {
 	return m.c["lyrics"]
 }
 
-func (m *metadataVorbis) Comment() string {
+func (m *MetadataVorbis) Comment() string {
 	if m.c["comment"] != "" {
 		return m.c["comment"]
 	}
 	return m.c["description"]
 }
 
-func (m *metadataVorbis) Picture() *Picture {
+func (m *MetadataVorbis) Picture() *Picture {
 	return m.p
 }