Merge pull request #24 from wader/skip-extended-header
Read and skip extended header bytes for 2.3 and 2.4
This commit is contained in:
commit
1c1d74b935
56
id3v2.go
56
id3v2.go
@ -52,14 +52,16 @@ type id3v2Header struct {
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}
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// readID3v2Header reads the ID3v2 header from the given io.Reader.
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func readID3v2Header(r io.Reader) (*id3v2Header, error) {
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b, err := readBytes(r, 10)
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// offset it number of bytes of header that was read
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func readID3v2Header(r io.Reader) (h *id3v2Header, offset int, err error) {
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offset = 10
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b, err := readBytes(r, offset)
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if err != nil {
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return nil, fmt.Errorf("expected to read 10 bytes (ID3v2Header): %v", err)
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return nil, 0, fmt.Errorf("expected to read 10 bytes (ID3v2Header): %v", err)
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}
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if string(b[0:3]) != "ID3" {
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return nil, fmt.Errorf("expected to read \"ID3\"")
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return nil, 0, fmt.Errorf("expected to read \"ID3\"")
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}
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b = b[3:]
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@ -74,17 +76,50 @@ func readID3v2Header(r io.Reader) (*id3v2Header, error) {
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case 0, 1:
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fallthrough
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default:
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return nil, fmt.Errorf("ID3 version: %v, expected: 2, 3 or 4", uint(b[0]))
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return nil, 0, fmt.Errorf("ID3 version: %v, expected: 2, 3 or 4", uint(b[0]))
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}
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// NB: We ignore b[1] (the revision) as we don't currently rely on it.
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return &id3v2Header{
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h = &id3v2Header{
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Version: vers,
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Unsynchronisation: getBit(b[2], 7),
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ExtendedHeader: getBit(b[2], 6),
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Experimental: getBit(b[2], 5),
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Size: get7BitChunkedInt(b[3:7]),
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}, nil
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}
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if h.ExtendedHeader {
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switch vers {
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case ID3v2_3:
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b, err := readBytes(r, 4)
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if err != nil {
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return nil, 0, fmt.Errorf("expected to read 4 bytes (ID3v23 extended header len): %v", err)
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}
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// skip header, size is excluding len bytes
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extendedHeaderSize := getInt(b)
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_, err = readBytes(r, extendedHeaderSize)
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if err != nil {
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return nil, 0, fmt.Errorf("expected to read %d bytes (ID3v23 skip extended header): %v", extendedHeaderSize, err)
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}
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offset += extendedHeaderSize
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case ID3v2_4:
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b, err := readBytes(r, 4)
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if err != nil {
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return nil, 0, fmt.Errorf("expected to read 4 bytes (ID3v24 extended header len): %v", err)
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}
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// skip header, size is synchsafe int including len bytes
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extendedHeaderSize := get7BitChunkedInt(b) - 4
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_, err = readBytes(r, extendedHeaderSize)
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if err != nil {
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return nil, 0, fmt.Errorf("expected to read %d bytes (ID3v24 skip extended header): %v", extendedHeaderSize, err)
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}
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offset += extendedHeaderSize
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default:
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// nop, only 2.3 and 2.4 should have extended header
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}
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}
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return h, offset, nil
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}
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// id3v2FrameFlags is a type which represents the flags which can be set on an ID3v2 frame.
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@ -184,8 +219,7 @@ func readID3v2_4FrameHeader(r io.Reader) (name string, size int, headerSize int,
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}
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// readID3v2Frames reads ID3v2 frames from the given reader using the ID3v2Header.
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func readID3v2Frames(r io.Reader, h *id3v2Header) (map[string]interface{}, error) {
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offset := 10 // the size of the header
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func readID3v2Frames(r io.Reader, offset int, h *id3v2Header) (map[string]interface{}, error) {
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result := make(map[string]interface{})
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for offset < h.Size {
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@ -357,7 +391,7 @@ func (r *unsynchroniser) Read(p []byte) (int, error) {
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// ReadID3v2Tags parses ID3v2.{2,3,4} tags from the io.ReadSeeker into a Metadata, returning
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// non-nil error on failure.
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func ReadID3v2Tags(r io.ReadSeeker) (Metadata, error) {
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h, err := readID3v2Header(r)
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h, offset, err := readID3v2Header(r)
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if err != nil {
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return nil, err
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}
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@ -368,7 +402,7 @@ func ReadID3v2Tags(r io.ReadSeeker) (Metadata, error) {
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ur = &unsynchroniser{Reader: r}
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}
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f, err := readID3v2Frames(ur, h)
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f, err := readID3v2Frames(ur, offset, h)
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if err != nil {
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return nil, err
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}
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2
sum.go
2
sum.go
@ -137,7 +137,7 @@ func SumID3v1(r io.ReadSeeker) (string, error) {
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// SumID3v2 constructs a checksum of MP3 audio file data (assumed to have ID3v2 tags) provided by the
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// io.ReadSeeker which is metadata invariant.
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func SumID3v2(r io.ReadSeeker) (string, error) {
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header, err := readID3v2Header(r)
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header, _, err := readID3v2Header(r)
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if err != nil {
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return "", fmt.Errorf("error reading ID3v2 header: %v", err)
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}
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