1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
package rtcp
import (
"encoding/binary"
"fmt"
)
// The PictureLossIndication packet informs the encoder about the loss of an undefined amount of coded video data belonging to one or more pictures
type PictureLossIndication struct {
// SSRC of sender
SenderSSRC uint32
// SSRC where the loss was experienced
MediaSSRC uint32
}
var _ Packet = (*PictureLossIndication)(nil) // assert is a Packet
const (
pliLength = 2
)
// Marshal encodes the PictureLossIndication in binary
func (p PictureLossIndication) Marshal() ([]byte, error) {
/*
* PLI does not require parameters. Therefore, the length field MUST be
* 2, and there MUST NOT be any Feedback Control Information.
*
* The semantics of this FB message is independent of the payload type.
*/
rawPacket := make([]byte, p.len())
packetBody := rawPacket[headerLength:]
binary.BigEndian.PutUint32(packetBody, p.SenderSSRC)
binary.BigEndian.PutUint32(packetBody[4:], p.MediaSSRC)
h := Header{
Count: FormatPLI,
Type: TypePayloadSpecificFeedback,
Length: pliLength,
}
hData, err := h.Marshal()
if err != nil {
return nil, err
}
copy(rawPacket, hData)
return rawPacket, nil
}
// Unmarshal decodes the PictureLossIndication from binary
func (p *PictureLossIndication) Unmarshal(rawPacket []byte) error {
if len(rawPacket) < (headerLength + (ssrcLength * 2)) {
return errPacketTooShort
}
var h Header
if err := h.Unmarshal(rawPacket); err != nil {
return err
}
if h.Type != TypePayloadSpecificFeedback || h.Count != FormatPLI {
return errWrongType
}
p.SenderSSRC = binary.BigEndian.Uint32(rawPacket[headerLength:])
p.MediaSSRC = binary.BigEndian.Uint32(rawPacket[headerLength+ssrcLength:])
return nil
}
// Header returns the Header associated with this packet.
func (p *PictureLossIndication) Header() Header {
return Header{
Count: FormatPLI,
Type: TypePayloadSpecificFeedback,
Length: pliLength,
}
}
func (p *PictureLossIndication) len() int {
return headerLength + ssrcLength*2
}
func (p *PictureLossIndication) String() string {
return fmt.Sprintf("PictureLossIndication %x %x", p.SenderSSRC, p.MediaSSRC)
}
// DestinationSSRC returns an array of SSRC values that this packet refers to.
func (p *PictureLossIndication) DestinationSSRC() []uint32 {
return []uint32{p.MediaSSRC}
}
|
