)
//register the type on init
func init() {
core.RegisterType("image/jpeg", func() core.Inspecter {
return &JpegPhoto{}
})
}
//This is what dates look like in EXIF tags.
const ExifDateFormat = "2006:01:02 15:04:05"
//apparently some phones/cameras have a bug which sets some of the exif values
//to 2002-12-08 12:00:00 +0000 UTC.
//so we need to ensure we ignore that date.
var exifDateBug = core.TimeMustParse(time.RFC3339, "2002-12-08T12:00:00Z")
//these fields might contain exif date-time strings (in "most-likely-to-be-correct" order)
var possibleExifDateTimeFields = []exif.FieldName{exif.DateTimeDigitized, exif.DateTime, exif.DateTimeOriginal}
//exif orientation flag
type ExifOrientation uint
//we define the angles in degrees clockwise.
//normal means no transform before rotation
//mirror means flip along a vertical axis before
//rotation, Undefined should be treated as Normal
const (
OrientedUndefined ExifOrientation = iota
OrientedNormal //1
OrientedMirror //2
if timescale == 0 {
return 0, fmt.Errorf("invalid timescale in mp4")
}
_, err = f.Read(buff)
if err != nil {
err = fmt.Errorf("read error: %s", err)
return 0, err
}
durationRaw := binary.BigEndian.Uint32(buff)
//real duration is raw/timescale
duration = int64((float64(durationRaw) / float64(timescale)) + 0.5)
return
}
//now that is seconds since 1904-01-01 00:00:00
var mp4DateEpoch = core.TimeMustParse(time.RFC3339, "1904-01-01T00:00:00Z")
//to find the creation date from the "mvhd" atom, take bytes 5-8 as
//a Big Endian uint32, as the number of seconds since
// 1904-01-01 00:00:00 (?)
func getMp4CreationTimeFromMvhdAtom(f io.ReadSeeker) (time.Time, error) {
//now we have it! bytes 5-8
f.Seek(4, 1)
buff := make([]byte, 4, 4)
_, err := f.Read(buff)
if err != nil {
err = fmt.Errorf("read error: %s", err)
return time.Time{}, err
}
createdUint := binary.BigEndian.Uint32(buff)
//and add our seconds