90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
package rtcp
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import (
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"encoding/binary"
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"fmt"
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)
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// The PictureLossIndication packet informs the encoder about the loss of an undefined amount of coded video data belonging to one or more pictures
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type PictureLossIndication struct {
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// SSRC of sender
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SenderSSRC uint32
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// SSRC where the loss was experienced
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MediaSSRC uint32
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}
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const (
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pliLength = 2
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)
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// Marshal encodes the PictureLossIndication in binary
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func (p PictureLossIndication) Marshal() ([]byte, error) {
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/*
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* PLI does not require parameters. Therefore, the length field MUST be
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* 2, and there MUST NOT be any Feedback Control Information.
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*
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* The semantics of this FB message is independent of the payload type.
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*/
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rawPacket := make([]byte, p.len())
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packetBody := rawPacket[headerLength:]
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binary.BigEndian.PutUint32(packetBody, p.SenderSSRC)
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binary.BigEndian.PutUint32(packetBody[4:], p.MediaSSRC)
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h := Header{
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Count: FormatPLI,
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Type: TypePayloadSpecificFeedback,
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Length: pliLength,
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}
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hData, err := h.Marshal()
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if err != nil {
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return nil, err
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}
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copy(rawPacket, hData)
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return rawPacket, nil
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}
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// Unmarshal decodes the PictureLossIndication from binary
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func (p *PictureLossIndication) Unmarshal(rawPacket []byte) error {
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if len(rawPacket) < (headerLength + (ssrcLength * 2)) {
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return errPacketTooShort
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}
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var h Header
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if err := h.Unmarshal(rawPacket); err != nil {
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return err
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}
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if h.Type != TypePayloadSpecificFeedback || h.Count != FormatPLI {
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return errWrongType
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}
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p.SenderSSRC = binary.BigEndian.Uint32(rawPacket[headerLength:])
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p.MediaSSRC = binary.BigEndian.Uint32(rawPacket[headerLength+ssrcLength:])
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return nil
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}
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// Header returns the Header associated with this packet.
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func (p *PictureLossIndication) Header() Header {
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return Header{
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Count: FormatPLI,
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Type: TypePayloadSpecificFeedback,
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Length: pliLength,
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}
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}
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func (p *PictureLossIndication) len() int {
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return headerLength + ssrcLength*2
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}
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func (p *PictureLossIndication) String() string {
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return fmt.Sprintf("PictureLossIndication %x %x", p.SenderSSRC, p.MediaSSRC)
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}
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// DestinationSSRC returns an array of SSRC values that this packet refers to.
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func (p *PictureLossIndication) DestinationSSRC() []uint32 {
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return []uint32{p.MediaSSRC}
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}
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