90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
|
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
|
||
|
|
}
|
||
|
|
|
||
|
|
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}
|
||
|
|
}
|