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97 lines
1.9 KiB
97 lines
1.9 KiB
package v1 |
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import ( |
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"bytes" |
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"fmt" |
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"io" |
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"strconv" |
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"github.com/Unbewohnte/id3ed/util" |
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) |
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// Retrieves ID3v1.1 field values of provided io.ReadSeeker |
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func Getv11Tag(rs io.ReadSeeker) (*ID3v11Tag, error) { |
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// set reader to the last 128 bytes |
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_, err := rs.Seek(-int64(ID3v1SIZE), io.SeekEnd) |
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if err != nil { |
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return nil, fmt.Errorf("could not seek: %s", err) |
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} |
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identifier, err := util.Read(rs, 3) |
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if err != nil { |
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return nil, err |
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} |
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if !bytes.Equal(identifier, []byte(ID3v1IDENTIFIER)) { |
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// no identifier, given file does not use ID3v1 |
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return nil, fmt.Errorf("does not use ID3v1: expected %s; got %s", ID3v1IDENTIFIER, identifier) |
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} |
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songname, err := util.ReadToString(rs, 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 := util.ReadToString(rs, 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 := util.ReadToString(rs, 30) |
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if err != nil { |
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return nil, err |
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} |
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yearStr, err := util.ReadToString(rs, 4) |
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if err != nil { |
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return nil, err |
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} |
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year, err := strconv.Atoi(yearStr) |
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if err != nil { |
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return nil, fmt.Errorf("could not convert yearbytes into int: %s", err) |
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} |
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comment, err := util.ReadToString(rs, 28) |
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if err != nil { |
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return nil, err |
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} |
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// skip 1 null byte |
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_, err = util.Read(rs, 1) |
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if err != nil { |
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return nil, err |
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} |
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trackByte, err := util.Read(rs, 1) |
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if err != nil { |
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return nil, err |
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} |
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track, err := util.ByteToInt(trackByte[0]) |
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if err != nil { |
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return nil, fmt.Errorf("cannot convert bytes to int: %s", err) |
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} |
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genreByte, err := util.Read(rs, 1) |
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if err != nil { |
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return nil, err |
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} |
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genreInt, err := util.ByteToInt(genreByte[0]) |
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if err != nil { |
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return nil, fmt.Errorf("cannot convert bytes to int: %s", err) |
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} |
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genre, exists := id3v1genres[int(genreInt)] |
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if !exists { |
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genre = "" |
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} |
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return &ID3v11Tag{ |
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SongName: songname, |
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Artist: artist, |
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Album: album, |
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Year: year, |
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Comment: comment, |
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Track: int(track), |
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Genre: genre, |
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}, nil |
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}
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