58 lines
1.2 KiB
Go
58 lines
1.2 KiB
Go
|
package rtp
|
||
|
|
|
||
|
|
import (
|
||
|
|
"math"
|
||
|
|
"sync"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Sequencer generates sequential sequence numbers for building RTP packets
|
||
|
|
type Sequencer interface {
|
||
|
|
NextSequenceNumber() uint16
|
||
|
|
RollOverCount() uint64
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewRandomSequencer returns a new sequencer starting from a random sequence
|
||
|
|
// number
|
||
|
|
func NewRandomSequencer() Sequencer {
|
||
|
|
return &sequencer{
|
||
|
|
sequenceNumber: uint16(globalMathRandomGenerator.Intn(math.MaxUint16)),
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// NewFixedSequencer returns a new sequencer starting from a specific
|
||
|
|
// sequence number
|
||
|
|
func NewFixedSequencer(s uint16) Sequencer {
|
||
|
|
return &sequencer{
|
||
|
|
sequenceNumber: s - 1, // -1 because the first sequence number prepends 1
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
type sequencer struct {
|
||
|
|
sequenceNumber uint16
|
||
|
|
rollOverCount uint64
|
||
|
|
mutex sync.Mutex
|
||
|
|
}
|
||
|
|
|
||
|
|
// NextSequenceNumber increment and returns a new sequence number for
|
||
|
|
// building RTP packets
|
||
|
|
func (s *sequencer) NextSequenceNumber() uint16 {
|
||
|
|
s.mutex.Lock()
|
||
|
|
defer s.mutex.Unlock()
|
||
|
|
|
||
|
|
s.sequenceNumber++
|
||
|
|
if s.sequenceNumber == 0 {
|
||
|
|
s.rollOverCount++
|
||
|
|
}
|
||
|
|
|
||
|
|
return s.sequenceNumber
|
||
|
|
}
|
||
|
|
|
||
|
|
// RollOverCount returns the amount of times the 16bit sequence number
|
||
|
|
// has wrapped
|
||
|
|
func (s *sequencer) RollOverCount() uint64 {
|
||
|
|
s.mutex.Lock()
|
||
|
|
defer s.mutex.Unlock()
|
||
|
|
|
||
|
|
return s.rollOverCount
|
||
|
|
}
|