137 lines
4.2 KiB
Go
137 lines
4.2 KiB
Go
// Copyright 2015, David Howden
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tag
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import (
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"errors"
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"io"
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"os"
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"strconv"
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"strings"
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)
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// id3v1Genres is a list of genres as given in the ID3v1 specification.
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var id3v1Genres = [...]string{
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"Blues", "Classic Rock", "Country", "Dance", "Disco", "Funk", "Grunge",
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"Hip-Hop", "Jazz", "Metal", "New Age", "Oldies", "Other", "Pop", "R&B",
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"Rap", "Reggae", "Rock", "Techno", "Industrial", "Alternative", "Ska",
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"Death Metal", "Pranks", "Soundtrack", "Euro-Techno", "Ambient",
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"Trip-Hop", "Vocal", "Jazz+Funk", "Fusion", "Trance", "Classical",
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"Instrumental", "Acid", "House", "Game", "Sound Clip", "Gospel",
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"Noise", "AlternRock", "Bass", "Soul", "Punk", "Space", "Meditative",
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"Instrumental Pop", "Instrumental Rock", "Ethnic", "Gothic",
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"Darkwave", "Techno-Industrial", "Electronic", "Pop-Folk",
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"Eurodance", "Dream", "Southern Rock", "Comedy", "Cult", "Gangsta",
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"Top 40", "Christian Rap", "Pop/Funk", "Jungle", "Native American",
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"Cabaret", "New Wave", "Psychadelic", "Rave", "Showtunes", "Trailer",
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"Lo-Fi", "Tribal", "Acid Punk", "Acid Jazz", "Polka", "Retro",
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"Musical", "Rock & Roll", "Hard Rock", "Folk", "Folk-Rock",
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"National Folk", "Swing", "Fast Fusion", "Bebob", "Latin", "Revival",
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"Celtic", "Bluegrass", "Avantgarde", "Gothic Rock", "Progressive Rock",
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"Psychedelic Rock", "Symphonic Rock", "Slow Rock", "Big Band",
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"Chorus", "Easy Listening", "Acoustic", "Humour", "Speech", "Chanson",
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"Opera", "Chamber Music", "Sonata", "Symphony", "Booty Bass", "Primus",
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"Porn Groove", "Satire", "Slow Jam", "Club", "Tango", "Samba",
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"Folklore", "Ballad", "Power Ballad", "Rhythmic Soul", "Freestyle",
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"Duet", "Punk Rock", "Drum Solo", "Acapella", "Euro-House", "Dance Hall",
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}
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// ErrNotID3v1 is an error which is returned when no ID3v1 header is found.
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var ErrNotID3v1 = errors.New("invalid ID3v1 header")
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// ReadID3v1Tags reads ID3v1 tags from the io.ReadSeeker. Returns ErrNotID3v1
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// if there are no ID3v1 tags, otherwise non-nil error if there was a problem.
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func ReadID3v1Tags(r io.ReadSeeker) (Metadata, error) {
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_, err := r.Seek(-128, os.SEEK_END)
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if err != nil {
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return nil, err
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}
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if tag, err := readString(r, 3); err != nil {
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return nil, err
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} else if tag != "TAG" {
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return nil, ErrNotID3v1
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}
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title, err := readString(r, 30)
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if err != nil {
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return nil, err
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}
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artist, err := readString(r, 30)
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if err != nil {
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return nil, err
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}
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album, err := readString(r, 30)
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if err != nil {
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return nil, err
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}
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year, err := readString(r, 4)
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if err != nil {
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return nil, err
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}
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commentBytes, err := readBytes(r, 29)
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if err != nil {
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return nil, err
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}
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var comment string
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var track int
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if commentBytes[27] == 0 {
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comment = strings.TrimSpace(string(commentBytes[:28]))
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track = int(commentBytes[28])
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}
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var genre string
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genreID, err := readBytes(r, 1)
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if err != nil {
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return nil, err
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}
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if int(genreID[0]) < len(id3v1Genres) {
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genre = id3v1Genres[int(genreID[0])]
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}
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m := make(map[string]interface{})
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m["title"] = strings.TrimSpace(title)
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m["artist"] = strings.TrimSpace(artist)
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m["album"] = strings.TrimSpace(album)
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m["year"] = strings.TrimSpace(year)
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m["comment"] = strings.TrimSpace(comment)
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m["track"] = track
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m["genre"] = genre
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return metadataID3v1(m), nil
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}
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// metadataID3v1 is the implementation of Metadata used for ID3v1 tags.
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type metadataID3v1 map[string]interface{}
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func (metadataID3v1) Format() Format { return ID3v1 }
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func (m metadataID3v1) Raw() map[string]interface{} { return m }
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func (m metadataID3v1) Title() string { return m["title"].(string) }
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func (m metadataID3v1) Album() string { return m["album"].(string) }
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func (m metadataID3v1) Artist() string { return m["artist"].(string) }
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func (m metadataID3v1) Genre() string { return m["genre"].(string) }
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func (m metadataID3v1) Year() int {
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y := m["year"].(string)
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n, err := strconv.Atoi(y)
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if err != nil {
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return 0
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}
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return n
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}
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func (m metadataID3v1) Track() (int, int) { return m["track"].(int), 0 }
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func (m metadataID3v1) AlbumArtist() string { return "" }
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func (m metadataID3v1) Composer() string { return "" }
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func (metadataID3v1) Disc() (int, int) { return 0, 0 }
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func (m metadataID3v1) Picture() *Picture { return nil }
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