❖ Simplified V1 ❖

util/conversion.go

@@ -7,8 +7,8 @@ import (
 )
 
 // Decodes given byte into integer
-func ByteToInt(gByte byte) (int64, error) {
+func ByteToInt(gByte byte) (int, error) {
-	integer, err := strconv.ParseInt(fmt.Sprintf("%d", gByte), 10, 64)
+	integer, err := strconv.Atoi(fmt.Sprintf("%d", gByte))
 	if err != nil {
 		return 0, err
 	}

v1/constants.go

@@ -3,3 +3,6 @@ package v1
 const ID3v1IDENTIFIER string = "TAG"
 const ID3v1SIZE int = 128 // bytes
 const ID3v1INVALIDGENRE int = 255
+
+const V1_0 string = "ID3v1.0"
+const V1_1 string = "ID3v1.1"

v1/id3v11_test.go

@@ -1,85 +0,0 @@
-package v1
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"testing"
-)
-
-var TESTV11TAG = &ID3v11Tag{
-	SongName: "testsong",
-	Artist:   "testartist",
-	Album:    "testalbum",
-	Year:     727,
-	Comment:  "testcomment",
-	Track:    5,
-	Genre:    "Blues",
-}
-
-func TestGetID3v11Tags(t *testing.T) {
-	testfile, err := os.Open(filepath.Join(TESTDATAPATH, "testreadv1.mp3"))
-	if err != nil {
-		t.Errorf("could not open file for testing: %s", err)
-	}
-	mp3tags, err := Getv11Tag(testfile)
-	if err != nil {
-		t.Errorf("GetID3v11Tag failed: %s", err)
-	}
-
-	if mp3tags.Artist != "Artist" {
-		fmt.Printf("%v", mp3tags.Artist)
-		t.Errorf("GetID3v11Tag failed:  expected artist %s; got %s", "Artist", mp3tags.Artist)
-	}
-
-	if mp3tags.Track != 8 {
-		t.Errorf("GetID3v11Tag failed: expected track %d; got %d", 8, mp3tags.Track)
-	}
-}
-
-// WILL ADD NEW "TAG" WITHOUT REMOVING THE OLD ONE !!!
-func TestWriteID3v11Tags(t *testing.T) {
-	f, err := os.OpenFile(filepath.Join(TESTDATAPATH, "testwritev1.mp3"), os.O_CREATE|os.O_RDWR, os.ModePerm)
-	if err != nil {
-		t.Errorf("%s", err)
-	}
-	defer f.Close()
-
-	tag := TESTV11TAG
-
-	err = tag.Write(f)
-	if err != nil {
-		t.Errorf("WriteID3v1Tags failed: %s", err)
-	}
-
-	readTags, err := Getv11Tag(f)
-	if err != nil {
-		t.Errorf("%s", err)
-	}
-
-	if readTags.Album != "testalbum" {
-		t.Errorf("WriteID3v11Tag failed: expected album %s; got %s", "testalbum", readTags.Album)
-	}
-
-	if readTags.Year != 727 {
-		t.Errorf("WriteID3v11Tag failed: expected year %d; got %d", 727, readTags.Year)
-	}
-
-	if readTags.Track != 10 {
-		t.Errorf("WriteID3v11Tag failed: expected track %d; got %d", 10, readTags.Track)
-	}
-}
-
-func TestWriteID3v11ToFile(t *testing.T) {
-	f, err := os.OpenFile(filepath.Join(TESTDATAPATH, "testwritev1.mp3"), os.O_CREATE|os.O_RDWR, os.ModePerm)
-	if err != nil {
-		t.Errorf("%s", err)
-	}
-
-	tag := TESTV11TAG
-
-	err = tag.WriteToFile(f)
-	if err != nil {
-		t.Errorf("WriteID3v1ToFile failed: %s", err)
-	}
-}

v1/read.go

@@ -9,14 +9,17 @@ import (
 	"github.com/Unbewohnte/id3ed/util"
 )
 
-// Retrieves ID3v1.1 field values of provided io.ReadSeeker
+// Retrieves ID3v1 field values of provided io.ReadSeeker (usually a file)
-func Getv11Tag(rs io.ReadSeeker) (*ID3v11Tag, error) {
+func Getv1Tag(rs io.ReadSeeker) (*ID3v1Tag, error) {
+	var tag ID3v1Tag
+
 	// set reader to the last 128 bytes
 	_, err := rs.Seek(-int64(ID3v1SIZE), io.SeekEnd)
 	if err != nil {
 		return nil, fmt.Errorf("could not seek: %s", err)
 	}
 
+	// ID
 	identifier, err := util.Read(rs, 3)
 	if err != nil {
 		return nil, err
@@ -27,21 +30,28 @@ func Getv11Tag(rs io.ReadSeeker) (*ID3v11Tag, error) {
 		return nil, fmt.Errorf("does not use ID3v1: expected %s; got %s", ID3v1IDENTIFIER, identifier)
 	}
 
+	// Songname
 	songname, err := util.ReadToString(rs, 30)
 	if err != nil {
 		return nil, err
 	}
+	tag.SongName = songname
 
+	// Artist
 	artist, err := util.ReadToString(rs, 30)
 	if err != nil {
 		return nil, err
 	}
+	tag.Artist = artist
 
+	// Album name
 	album, err := util.ReadToString(rs, 30)
 	if err != nil {
 		return nil, err
 	}
+	tag.Album = album
 
+	// Year
 	yearStr, err := util.ReadToString(rs, 4)
 	if err != nil {
 		return nil, err
@@ -50,28 +60,31 @@ func Getv11Tag(rs io.ReadSeeker) (*ID3v11Tag, error) {
 	if err != nil {
 		return nil, fmt.Errorf("could not convert yearbytes into int: %s", err)
 	}
+	tag.Year = year
 
-	comment, err := util.ReadToString(rs, 28)
+	// Comment and Track
-	if err != nil {
+	comment, err := util.Read(rs, 30)
-		return nil, err
-	}
-
-	// skip 1 null byte
-	_, err = util.Read(rs, 1)
 	if err != nil {
 		return nil, err
 	}
+	tag.Comment = util.ToString(comment)
+	tag.Track = 0
 
-	trackByte, err := util.Read(rs, 1)
+	var track int = 0
+	// check if 29th byte is null byte (v1.0 or v1.1)
+	if comment[28] == 0 {
+		// it is v1.1, track number exists
+		track, err = util.ByteToInt(comment[29])
 		if err != nil {
-		return nil, err
+			return nil, fmt.Errorf("could not get int from byte: %s", err)
 		}
+		tag.Track = uint8(track)
 
-	track, err := util.ByteToInt(trackByte[0])
+		comment = comment[0:28]
-	if err != nil {
+		tag.Comment = util.ToString(comment)
-		return nil, fmt.Errorf("cannot convert bytes to int: %s", err)
 	}
 
+	// Genre
 	genreByte, err := util.Read(rs, 1)
 	if err != nil {
 		return nil, err
@@ -84,14 +97,13 @@ func Getv11Tag(rs io.ReadSeeker) (*ID3v11Tag, error) {
 	if !exists {
 		genre = ""
 	}
+	tag.Genre = genre
+
+	if track == 0 {
+		tag.Version = V1_0
+	} else {
+		tag.Version = V1_1
+	}
 
-	return &ID3v11Tag{
+	return &tag, nil
-		SongName: songname,
-		Artist:   artist,
-		Album:    album,
-		Year:     year,
-		Comment:  comment,
-		Track:    int(track),
-		Genre:    genre,
-	}, nil
 }

v1/tag.go

@@ -3,14 +3,12 @@ package v1
 // https://id3.org/ID3v1 - documentation
 
 type ID3v1Tag struct {
+	Version  string
 	SongName string
 	Artist   string
 	Album    string
 	Year     int
 	Comment  string
+	Track    uint8 // basically a byte, but converted to int for convenience
 	Genre    string
 }
-
-func (*ID3v1Tag) Version() int {
-	return 10
-}

v1/v11tag.go

@@ -1,15 +0,0 @@
-package v1
-
-type ID3v11Tag struct {
-	SongName string
-	Artist   string
-	Album    string
-	Year     int
-	Comment  string
-	Track    int
-	Genre    string
-}
-
-func (*ID3v11Tag) Version() int {
-	return 11
-}

v1/v11write.go

@@ -1,129 +0,0 @@
-package v1
-
-import (
-	"bytes"
-	"encoding/binary"
-	"fmt"
-	"io"
-	"os"
-
-	"github.com/Unbewohnte/id3ed/util"
-)
-
-// Writes given ID3v1.1 tag to dst
-// NOTE: will not remove already existing ID3v1.1 tag if it`s present,
-// use ⁕WriteToFile⁕ method if you`re working with REAL mp3 files !!!
-func (tag *ID3v11Tag) Write(dst io.WriteSeeker) error {
-	dst.Seek(0, io.SeekEnd)
-
-	// TAG
-	_, err := dst.Write([]byte(ID3v1IDENTIFIER))
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Song name
-	err = util.WriteToExtent(dst, []byte(tag.SongName), 30)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Artist
-	err = util.WriteToExtent(dst, []byte(tag.Artist), 30)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Album
-	err = util.WriteToExtent(dst, []byte(tag.Album), 30)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Year
-	err = util.WriteToExtent(dst, []byte(fmt.Sprint(tag.Year)), 4)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Comment
-	err = util.WriteToExtent(dst, []byte(tag.Comment), 28)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	_, err = dst.Write([]byte{0})
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	// Track
-	trackBytes := make([]byte, 1)
-	binary.PutVarint(trackBytes, int64(tag.Track))
-	_, err = dst.Write(trackBytes)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	//Genre
-	genreCode := util.GetKey(id3v1genres, tag.Genre)
-	if genreCode == -1 {
-		// if no genre found - encode genre code as 255
-		genreCode = ID3v1INVALIDGENRE
-	}
-	genrebyte := make([]byte, 1)
-	binary.PutVarint(genrebyte, int64(genreCode))
-
-	err = util.WriteToExtent(dst, genrebyte, 1)
-	if err != nil {
-		return fmt.Errorf("could not write to dst: %s", err)
-	}
-
-	return nil
-}
-
-// Checks for existing ID3v1.1 tag in file, if present - removes it and replaces with provided tag
-func (tag *ID3v11Tag) WriteToFile(f *os.File) error {
-	defer f.Close()
-
-	// check for existing ID3v1.1 tag
-	_, err := f.Seek(-int64(ID3v1SIZE), io.SeekEnd)
-	if err != nil {
-		return fmt.Errorf("could not seek: %s", err)
-	}
-
-	identifier, err := util.Read(f, 3)
-	if err != nil {
-		// return err
-		return err
-
-	}
-
-	if !bytes.Equal(identifier, []byte(ID3v1IDENTIFIER)) {
-		// no existing identifier, just write given tag
-		err = tag.Write(f)
-		if err != nil {
-			return fmt.Errorf("could not write to writer: %s", err)
-		}
-		return nil
-	}
-
-	// does contain ID3v1.1 tag. Removing it
-	fStats, err := f.Stat()
-	if err != nil {
-		return fmt.Errorf("cannot get file stats: %s", err)
-	}
-
-	err = f.Truncate(fStats.Size() - int64(ID3v1SIZE))
-	if err != nil {
-		return fmt.Errorf("could not truncate file %s", err)
-	}
-
-	// writing new tag
-	err = tag.Write(f)
-	if err != nil {
-		return fmt.Errorf("could not write to writer: %s", err)
-	}
-
-	return nil
-}

v1/v1_test.go

@@ -27,8 +27,20 @@ func TestGetv1Tags(t *testing.T) {
 		t.Errorf("GetID3v1Tag failed: %s", err)
 	}
 
+	if tag.Version != V1_1 {
+		t.Errorf("GetID3v1Tag failed: expected version to be %s; got %s", V1_1, tag.Version)
+	}
+
 	if tag.Comment != "Comment here " {
-		t.Errorf("GetID3v1Tag failed: expected %s; got %s", "Comment here ", tag.Comment)
+		t.Errorf("GetID3v1Tag failed: expected comment to be %s; got %s", "Comment here ", tag.Comment)
+	}
+
+	if tag.Genre != "Soundtrack" {
+		t.Errorf("GetID3v1Tag failed: expected genre to be %s; got %s", "Soundtrack", tag.Genre)
+	}
+
+	if tag.Track != 8 {
+		t.Errorf("GetID3v1Tag failed: expected track number to be %d; got %d", 8, tag.Track)
 	}
 }
 
@@ -42,23 +54,23 @@ func TestWritev1Tags(t *testing.T) {
 	tag := TESTv1TAG
 
 	// writing a tag
-	err = tag.Write(f)
+	err = tag.write(f)
 	if err != nil {
 		t.Errorf("WriteID3v1Tag failed: %s", err)
 	}
 
 	// reading a tag
-	readTags, err := Getv1Tag(f)
+	readTag, err := Getv1Tag(f)
 	if err != nil {
 		t.Errorf("%s", err)
 	}
 
-	if readTags.Album != "testalbum" {
+	if readTag.Album != "testalbum" {
-		t.Errorf("WriteID3v1Tag failed: expected %s; got %s", "testalbum", readTags.Album)
+		t.Errorf("WriteID3v1Tag failed: expected %s; got %s", "testalbum", readTag.Album)
 	}
 
-	if readTags.Year != 727 {
+	if readTag.Year != 727 {
-		t.Errorf("WriteID3v1Tag failed: expected %d; got %d", 727, readTags.Year)
+		t.Errorf("WriteID3v1Tag failed: expected %d; got %d", 727, readTag.Year)
 	}
 }
 

v1/v1read.go

@@ -1,80 +0,0 @@
-package v1
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"strconv"
-
-	"github.com/Unbewohnte/id3ed/util"
-)
-
-// Retrieves ID3v1 field values of provided io.ReadSeeker (usually a file)
-func Getv1Tag(rs io.ReadSeeker) (*ID3v1Tag, error) {
-	// set reader to the last 128 bytes
-	_, err := rs.Seek(-int64(ID3v1SIZE), io.SeekEnd)
-	if err != nil {
-		return nil, fmt.Errorf("could not seek: %s", err)
-	}
-
-	tag, err := util.Read(rs, 3)
-	if err != nil {
-		return nil, err
-	}
-
-	if !bytes.Equal(tag, []byte(ID3v1IDENTIFIER)) {
-		// no TAG, given file does not use ID3v1
-		return nil, fmt.Errorf("does not use ID3v1: expected %s; got %s", ID3v1IDENTIFIER, tag)
-	}
-
-	songname, err := util.ReadToString(rs, 30)
-	if err != nil {
-		return nil, err
-	}
-
-	artist, err := util.ReadToString(rs, 30)
-	if err != nil {
-		return nil, err
-	}
-
-	album, err := util.ReadToString(rs, 30)
-	if err != nil {
-		return nil, err
-	}
-
-	yearStr, err := util.ReadToString(rs, 4)
-	if err != nil {
-		return nil, err
-	}
-	year, err := strconv.Atoi(yearStr)
-	if err != nil {
-		return nil, fmt.Errorf("could not convert yearbytes into int: %s", err)
-	}
-
-	comment, err := util.ReadToString(rs, 30)
-	if err != nil {
-		return nil, err
-	}
-
-	genreByte, err := util.Read(rs, 1)
-	if err != nil {
-		return nil, err
-	}
-	genreInt, err := util.ByteToInt(genreByte[0])
-	if err != nil {
-		return nil, fmt.Errorf("cannot convert bytes to int: %s", err)
-	}
-	genre, exists := id3v1genres[int(genreInt)]
-	if !exists {
-		genre = ""
-	}
-
-	return &ID3v1Tag{
-		SongName: songname,
-		Artist:   artist,
-		Album:    album,
-		Year:     year,
-		Comment:  comment,
-		Genre:    genre,
-	}, nil
-}

v1/write.go

@@ -10,10 +10,10 @@ import (
 	"github.com/Unbewohnte/id3ed/util"
 )
 
-// Writes given ID3v1.0 tag to given io.WriteSeeker.
+// Writes given ID3v1.0 or ID3v1.1 tag to given io.WriteSeeker.
 // NOTE: will not remove already existing ID3v1 tag if it`s present,
 // use ⁕WriteToFile⁕ method if you`re working with REAL mp3 files !!!
-func (tag *ID3v1Tag) Write(dst io.WriteSeeker) error {
+func (tag *ID3v1Tag) write(dst io.WriteSeeker) error {
 	dst.Seek(0, io.SeekEnd)
 
 	// ID
@@ -46,11 +46,35 @@ func (tag *ID3v1Tag) Write(dst io.WriteSeeker) error {
 		return fmt.Errorf("could not write to writer: %s", err)
 	}
 
-	// Comment
+	// Comment and Track
+
+	// check for track number, if specified and valid - comment must be shrinked to 28 bytes and 29th
+	// byte must be 0 byte (use ID3v1.1 instead of v1.0)
+	if tag.Track == 0 {
+		// write only 30 bytes long comment without track
 		err = util.WriteToExtent(dst, []byte(tag.Comment), 30)
 		if err != nil {
 			return fmt.Errorf("could not write to writer: %s", err)
 		}
+	} else {
+		// write 28 bytes long shrinked comment
+		err = util.WriteToExtent(dst, []byte(tag.Comment), 28)
+		if err != nil {
+			return fmt.Errorf("could not write to writer: %s", err)
+		}
+
+		// write 0 byte as padding
+		_, err = dst.Write([]byte{0})
+		if err != nil {
+			return fmt.Errorf("could not write to writer: %s", err)
+		}
+
+		// write track byte
+		_, err = dst.Write([]byte{byte(tag.Track)})
+		if err != nil {
+			return fmt.Errorf("could not write to writer: %s", err)
+		}
+	}
 
 	// Genre
 	genreCode := util.GetKey(id3v1genres, tag.Genre)
@@ -69,7 +93,7 @@ func (tag *ID3v1Tag) Write(dst io.WriteSeeker) error {
 	return nil
 }
 
-// Checks for existing ID3v1 tag in file, if present - removes it and replaces with provided tag
+// Checks for existing ID3v1 or ID3v1.1 tag in file, if present - removes it and replaces with provided tag
 func (tag *ID3v1Tag) WriteToFile(f *os.File) error {
 	defer f.Close()
 
@@ -83,7 +107,7 @@ func (tag *ID3v1Tag) WriteToFile(f *os.File) error {
 
 	if !bytes.Equal(identifier, []byte(ID3v1IDENTIFIER)) {
 		// no existing identifier, just write given tag
-		err = tag.Write(f)
+		err = tag.write(f)
 		if err != nil {
 			return err
 		}
@@ -101,8 +125,8 @@ func (tag *ID3v1Tag) WriteToFile(f *os.File) error {
 		return fmt.Errorf("could not truncate file %s", err)
 	}
 
-	// writing new tag
+	// writing a new tag
-	err = tag.Write(f)
+	err = tag.write(f)
 	if err != nil {
 		return fmt.Errorf("could not write to writer: %s", err)
 	}

v2/constants.go

@@ -7,6 +7,6 @@ const V2_2 string = "ID3v2.2"
 const V2_3 string = "ID3v2.3"
 const V2_4 string = "ID3v2.4"
 
-const V2_2FrameNameSize uint = 3
+const V2_2FrameIDSize uint = 3
-const V2_3FrameNameSize uint = 4
+const V2_3FrameIDSize uint = 4
-const V2_4FrameNameSize uint = 4
+const V2_4FrameIDSize uint = 4

v2/v2tag.go

@@ -1,34 +1,6 @@
 package v2
 
-// type ID3v2Tag struct {
+type ID3v2Tag struct {
-// 	Header Header
+	Header Header
-// 	Frames []Frame
+	Frames []Frame
-// }
+}
-
-// type V2TagReader interface {
-// 	ReadFrames(io.ReadSeeker) ([]*Frame, error)
-// 	GetHeader(io.ReadSeeker) (*Header, error)
-// 	HasPadding(io.ReadSeeker) (bool, error)
-// }
-
-// type V2TagWriter interface {
-// 	Write(*os.File) error
-// }
-
-// func Get(f *os.File) (*ID3v2Tag, error) {
-// 	var tag ID3v2Tag
-
-// 	header, err := GetHeader(f)
-// 	if err != nil {
-// 		return nil, err
-// 	}
-// 	frames, err := GetFrames(f)
-// 	if err != nil {
-// 		return nil, err
-// 	}
-
-// 	tag.Header = header
-// 	tag.Frames = frames
-
-// 	return &tag, nil
-// }