mirror of
https://github.com/cnotch/ipchub.git
synced 2025-09-26 19:41:18 +08:00
69 lines
2.0 KiB
Go
69 lines
2.0 KiB
Go
// Copyright (c) 2019,CAOHONGJU All rights reserved.
|
||
// Use of this source code is governed by a MIT-style
|
||
// license that can be found in the LICENSE file.
|
||
|
||
package rtp
|
||
|
||
import (
|
||
"encoding/binary"
|
||
"time"
|
||
)
|
||
|
||
const jan1970 = 0x83aa7e80
|
||
|
||
// SyncClock .
|
||
type SyncClock struct {
|
||
// NTP Timestamp（Network time protocol）SR包发送时的绝对时间值。
|
||
// NTP的作用是同步不同的RTP媒体流。
|
||
// NTP时间戳，它的前32位是从1900 年1 月1 日0 时开始到现在的以秒为单位的整数部，
|
||
// 后32 位是此时间的小数部，因此，它可以肯定的表示了数据发送出去的绝对时间。
|
||
NTPTime int64 // 此处转换成自 January 1, year 1 以来的纳秒数
|
||
// RTP Timestamp：与NTP时间戳对应，
|
||
// 与RTP数据包中的RTP时间戳具有相同的单位和随机初始值。
|
||
RTPTime uint32
|
||
RTPTimeUnit float64 // RTP时间单位，每个RTP时间的纳秒数
|
||
|
||
initOn time.Time // 初始化时间
|
||
}
|
||
|
||
// Init 初始化同步时钟
|
||
func (sc *SyncClock) Init(clockRate int) {
|
||
sc.initOn = time.Now()
|
||
sc.NTPTime = sc.initOn.UnixNano()
|
||
sc.RTPTimeUnit = float64(time.Second) / float64(clockRate)
|
||
}
|
||
|
||
// LocalTime 本地时间
|
||
func (sc *SyncClock) LocalTime() time.Time {
|
||
return time.Unix(0, sc.NTPTime).In(time.Local)
|
||
}
|
||
|
||
// Decode .
|
||
func (sc *SyncClock) Decode(data []byte) (ok bool) {
|
||
if data[1] == 200 {
|
||
msw := binary.BigEndian.Uint32(data[8:])
|
||
lsw := binary.BigEndian.Uint32(data[12:])
|
||
sc.RTPTime = binary.BigEndian.Uint32(data[16:])
|
||
sc.NTPTime = int64(msw-jan1970)*int64(time.Second) + (int64(lsw)*1000_000_000)>>32
|
||
ok = true
|
||
}
|
||
return
|
||
}
|
||
|
||
// GetRelativeNtp .
|
||
func (sc *SyncClock) RelativeNtpNow() int64 {
|
||
return int64(time.Now().Sub(sc.initOn))
|
||
}
|
||
|
||
// RelativeNtp .
|
||
func (sc *SyncClock) RelativeNtp(rtptime uint32) int64 {
|
||
diff := int64(rtptime) - int64(sc.RTPTime)
|
||
return int64(float64(diff) * sc.RTPTimeUnit)
|
||
}
|
||
|
||
// AbsoluteNtp .
|
||
func (sc *SyncClock) AbsoluteNtp(rtptime uint32) int64 {
|
||
diff := int64(rtptime) - int64(sc.RTPTime)
|
||
return sc.NTPTime + int64(float64(diff)*sc.RTPTimeUnit)
|
||
}
|