YTSFlix_Go/vendor/github.com/asticode/go-astits/dvb.go

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2018-11-04 14:58:15 +00:00
package astits
import (
"fmt"
"time"
)
// parseDVBTime parses a DVB time
// This field is coded as 16 bits giving the 16 LSBs of MJD followed by 24 bits coded as 6 digits in 4 - bit Binary
// Coded Decimal (BCD). If the start time is undefined (e.g. for an event in a NVOD reference service) all bits of the
// field are set to "1".
// I apologize for the computation which is really messy but details are given in the documentation
// Page: 160 | Annex C | Link: https://www.dvb.org/resources/public/standards/a38_dvb-si_specification.pdf
func parseDVBTime(i []byte, offset *int) (t time.Time) {
// Date
var mjd = uint16(i[*offset])<<8 | uint16(i[*offset+1])
var yt = int((float64(mjd) - 15078.2) / 365.25)
var mt = int((float64(mjd) - 14956.1 - float64(int(float64(yt)*365.25))) / 30.6001)
var d = int(float64(mjd) - 14956 - float64(int(float64(yt)*365.25)) - float64(int(float64(mt)*30.6001)))
var k int
if mt == 14 || mt == 15 {
k = 1
}
var y = yt + k
var m = mt - 1 - k*12
t, _ = time.Parse("06-01-02", fmt.Sprintf("%d-%d-%d", y, m, d))
*offset += 2
// Time
t = t.Add(parseDVBDurationSeconds(i, offset))
return
}
// parseDVBDurationMinutes parses a minutes duration
// 16 bit field containing the duration of the event in hours, minutes. format: 4 digits, 4 - bit BCD = 18 bit
func parseDVBDurationMinutes(i []byte, offset *int) (d time.Duration) {
d = parseDVBDurationByte(i[*offset])*time.Hour + parseDVBDurationByte(i[*offset+1])*time.Minute
*offset += 2
return
}
// parseDVBDurationSeconds parses a seconds duration
// 24 bit field containing the duration of the event in hours, minutes, seconds. format: 6 digits, 4 - bit BCD = 24 bit
func parseDVBDurationSeconds(i []byte, offset *int) (d time.Duration) {
d = parseDVBDurationByte(i[*offset])*time.Hour + parseDVBDurationByte(i[*offset+1])*time.Minute + parseDVBDurationByte(i[*offset+2])*time.Second
*offset += 3
return
}
// parseDVBDurationByte parses a duration byte
func parseDVBDurationByte(i byte) time.Duration {
return time.Duration(uint8(i)>>4*10 + uint8(i)&0xf)
}