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Correctly parse ID3 2.3 and 2.4 frame flags.

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Note: wasn't causing any know issues, but needed to be made consistent with the spec!
This commit is contained in:
David Howden 2015-06-28 12:34:42 +10:00
parent bda3a1fa8b
commit 6af476df94
1 changed files with 44 additions and 19 deletions
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63
id3v2.go
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@ -57,20 +57,40 @@ func readID3v2Header(r io.Reader) (*ID3v2Header, error) {
// ID3v2FrameFlags is a type which represents the flags which can be set on an ID3v2 frame.
type ID3v2FrameFlags struct {
// Message
// Message (ID3 2.3.0 and 2.4.0)
TagAlterPreservation bool
FileAlterPreservation bool
ReadOnly bool
// Format
GroupIdentity bool
Compression bool
Encryption bool
// Format (ID3 2.3.0 and 2.4.0)
Compression bool
Encryption bool
GroupIdentity bool
// ID3 2.4.0 only (see http://id3.org/id3v2.4.0-structure sec 4.1)
Unsynchronisation bool
DataLengthIndicator bool
}
func readID3v2FrameFlags(r io.Reader) (*ID3v2FrameFlags, error) {
func readID3v23FrameFlags(r io.Reader) (*ID3v2FrameFlags, error) {
b, err := readBytes(r, 2)
if err != nil {
return nil, err
}
msg := b[0]
fmt := b[1]
return &ID3v2FrameFlags{
TagAlterPreservation: getBit(msg, 7),
FileAlterPreservation: getBit(msg, 6),
ReadOnly: getBit(msg, 5),
Compression: getBit(fmt, 7),
Encryption: getBit(fmt, 6),
GroupIdentity: getBit(fmt, 5),
}, nil
}
func readID3v24FrameFlags(r io.Reader) (*ID3v2FrameFlags, error) {
b, err := readBytes(r, 2)
if err != nil {
return nil, err
@ -83,12 +103,13 @@ func readID3v2FrameFlags(r io.Reader) (*ID3v2FrameFlags, error) {
TagAlterPreservation: getBit(msg, 6),
FileAlterPreservation: getBit(msg, 5),
ReadOnly: getBit(msg, 4),
GroupIdentity: getBit(fmt, 7),
GroupIdentity: getBit(fmt, 6),
Compression: getBit(fmt, 3),
Encryption: getBit(fmt, 2),
Unsynchronisation: getBit(fmt, 1),
DataLengthIndicator: getBit(fmt, 0),
}, nil
}
func readID3v2_2FrameHeader(r io.Reader) (name string, size int, headerSize int, err error) {
@ -150,7 +171,7 @@ func readID3v2Frames(r io.Reader, h *ID3v2Header) (map[string]interface{}, error
if err != nil {
return nil, err
}
flags, err = readID3v2FrameFlags(r)
flags, err = readID3v23FrameFlags(r)
headerSize += 2
case ID3v2_4:
@ -158,7 +179,7 @@ func readID3v2Frames(r io.Reader, h *ID3v2Header) (map[string]interface{}, error
if err != nil {
return nil, err
}
flags, err = readID3v2FrameFlags(r)
flags, err = readID3v24FrameFlags(r)
headerSize += 2
}
@ -180,18 +201,22 @@ func readID3v2Frames(r io.Reader, h *ID3v2Header) (map[string]interface{}, error
offset += headerSize + size
// Check this stuff out...
if flags != nil && flags.DataLengthIndicator {
_, err = read7BitChunkedInt(r, 4) // read 4
if err != nil {
return nil, err
if flags != nil {
if flags.Compression {
_, err = read7BitChunkedInt(r, 4) // read 4
if err != nil {
return nil, err
}
size -= 4
}
size -= 4
}
if flags != nil && flags.Unsynchronisation {
// FIXME: Implement this.
continue
if flags.Encryption {
_, err = readBytes(r, 1) // read 1 byte of encryption method
if err != nil {
return nil, err
}
size -= 1
}
}
b, err := readBytes(r, size)