108 lines
2.6 KiB
Go
108 lines
2.6 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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// A FIREntry is a (SSRC, seqno) pair, as carried by FullIntraRequest.
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type FIREntry struct {
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SSRC uint32
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SequenceNumber uint8
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}
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// The FullIntraRequest packet is used to reliably request an Intra frame
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// in a video stream. See RFC 5104 Section 3.5.1. This is not for loss
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// recovery, which should use PictureLossIndication (PLI) instead.
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type FullIntraRequest struct {
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SenderSSRC uint32
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MediaSSRC uint32
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FIR []FIREntry
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}
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const (
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firOffset = 8
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)
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var _ Packet = (*FullIntraRequest)(nil)
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// Marshal encodes the FullIntraRequest
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func (p FullIntraRequest) Marshal() ([]byte, error) {
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rawPacket := make([]byte, firOffset+(len(p.FIR)*8))
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binary.BigEndian.PutUint32(rawPacket, p.SenderSSRC)
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binary.BigEndian.PutUint32(rawPacket[4:], p.MediaSSRC)
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for i, fir := range p.FIR {
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binary.BigEndian.PutUint32(rawPacket[firOffset+8*i:], fir.SSRC)
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rawPacket[firOffset+8*i+4] = fir.SequenceNumber
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}
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h := p.Header()
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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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return append(hData, rawPacket...), nil
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}
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// Unmarshal decodes the TransportLayerNack
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func (p *FullIntraRequest) Unmarshal(rawPacket []byte) error {
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if len(rawPacket) < (headerLength + ssrcLength) {
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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 len(rawPacket) < (headerLength + int(4*h.Length)) {
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return errPacketTooShort
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}
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if h.Type != TypePayloadSpecificFeedback || h.Count != FormatFIR {
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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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for i := headerLength + firOffset; i < (headerLength + int(h.Length*4)); i += 8 {
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p.FIR = append(p.FIR, FIREntry{
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binary.BigEndian.Uint32(rawPacket[i:]),
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rawPacket[i+4],
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})
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}
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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 *FullIntraRequest) Header() Header {
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return Header{
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Count: FormatFIR,
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Type: TypePayloadSpecificFeedback,
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Length: uint16((p.len() / 4) - 1),
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}
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}
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func (p *FullIntraRequest) len() int {
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return headerLength + firOffset + len(p.FIR)*8
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}
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func (p *FullIntraRequest) String() string {
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out := fmt.Sprintf("FullIntraRequest %x %x",
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p.SenderSSRC, p.MediaSSRC)
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for _, e := range p.FIR {
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out += fmt.Sprintf(" (%x %v)", e.SSRC, e.SequenceNumber)
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}
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return out
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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 *FullIntraRequest) DestinationSSRC() []uint32 {
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ssrcs := make([]uint32, 0, len(p.FIR))
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for _, entry := range p.FIR {
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ssrcs = append(ssrcs, entry.SSRC)
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}
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return ssrcs
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}
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