83 lines
1.6 KiB
Go
83 lines
1.6 KiB
Go
package mov
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"time"
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)
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const epochAdjust = 2082844800
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// Created attempts to find a created time from the metadata in a .mov file.
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func Created(file io.ReadSeeker) (time.Time, error) {
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c, _, err := times(file)
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return c, err
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}
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// Modified attempts to find a modification time from the metadata in a .mov
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// file.
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func Modified(file io.ReadSeeker) (time.Time, error) {
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_, m, err := times(file)
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return m, err
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}
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// times seeks around in file and finds Created and Modified times.
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//
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// This was transcibed from http://stackoverflow.com/a/21395803
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func times(file io.ReadSeeker) (time.Time, time.Time, error) {
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var c, m time.Time
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var i int64
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var err error
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buf := [8]byte{}
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for {
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_, err := file.Read(buf[:])
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if err != nil {
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return c, m, err
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}
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if bytes.Equal(buf[4:8], []byte("moov")) {
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break
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} else {
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atomSize := binary.BigEndian.Uint32(buf[:])
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file.Seek(int64(atomSize)-8, 1)
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}
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}
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_, err = file.Read(buf[:])
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if err != nil {
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return c, m, err
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}
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s := string(buf[4:8])
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switch s {
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case "mvhd":
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if _, err := file.Seek(4, 1); err != nil {
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return c, m, err
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}
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_, err = file.Read(buf[:4])
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if err != nil {
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return c, m, err
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}
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i = int64(binary.BigEndian.Uint32(buf[:4]))
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c := time.Unix(i-epochAdjust, 0).Local()
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_, err = file.Read(buf[:4])
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if err != nil {
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return c, m, err
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}
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i = int64(binary.BigEndian.Uint32(buf[:4]))
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m := time.Unix(i-epochAdjust, 0).Local()
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return c, m, nil
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case "cmov":
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return c, m, errors.New("moov atom is compressed")
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default:
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return c, m, errors.New("expected to find 'mvhd' header, didn't")
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}
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}
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