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@ -4,20 +4,28 @@ 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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type HeaderFlags struct { |
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Unsynchronisated bool |
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HasExtendedHeader bool |
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Experimental bool |
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FooterPresent bool |
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} |
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// ID3v2.x header structure
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type Header struct { |
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Identifier string |
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Version string |
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Unsynchronisated bool |
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Compressed bool |
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Size int64 // size of the whole tag - 10 header bytes
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Identifier string |
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Flags HeaderFlags |
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Version uint |
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Size int64 // size of the whole tag - 10 header bytes
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} |
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// Reads and structuralises ID3v2 header
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// Reads and structuralises ID3v2.3.0 or ID3v2.4.0 header
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func GetHeader(rs io.ReadSeeker) (*Header, error) { |
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var header Header |
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@ -51,23 +59,63 @@ func GetHeader(rs io.ReadSeeker) (*Header, error) {
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if err != nil { |
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return nil, err |
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} |
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header.Version = fmt.Sprintf("%d%d", -majorVersion, revisionNumber) |
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version, err := strconv.Atoi(fmt.Sprintf("%d%d", majorVersion, revisionNumber)) |
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if err != nil { |
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return nil, err |
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} |
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header.Version = uint(version) |
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// flags
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flags, 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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bits := fmt.Sprintf("%08b", flags) // 1 byte is 8 bits
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if bits[0] == 1 { |
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header.Unsynchronisated = true |
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} else { |
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header.Unsynchronisated = false |
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} |
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if bits[1] == 1 { |
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header.Compressed = true |
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} else { |
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header.Compressed = false |
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flagBits := fmt.Sprintf("%08b", flags) // 1 byte is 8 bits
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// v3.0 and v4.0 have different amount of flags
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switch version { |
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case 30: |
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if flagBits[0] == 1 { |
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header.Flags.Unsynchronisated = true |
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} else { |
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header.Flags.Unsynchronisated = false |
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} |
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if flagBits[1] == 1 { |
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header.Flags.HasExtendedHeader = true |
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} else { |
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header.Flags.HasExtendedHeader = false |
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} |
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if flagBits[2] == 1 { |
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header.Flags.Experimental = true |
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} else { |
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header.Flags.Experimental = false |
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} |
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// always false, because ID3v2.3.0 does not support footers
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header.Flags.FooterPresent = false |
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case 40: |
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if flagBits[0] == 1 { |
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header.Flags.Unsynchronisated = true |
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} else { |
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header.Flags.Unsynchronisated = false |
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} |
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if flagBits[1] == 1 { |
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header.Flags.HasExtendedHeader = true |
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} else { |
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header.Flags.HasExtendedHeader = false |
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} |
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if flagBits[2] == 1 { |
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header.Flags.Experimental = true |
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} else { |
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header.Flags.Experimental = false |
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} |
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if flagBits[3] == 1 { |
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header.Flags.FooterPresent = true |
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} else { |
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header.Flags.FooterPresent = false |
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} |
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} |
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// size
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