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package main
import (
"fmt"
"log"
"net"
"time"
"github.com/pion/interceptor"
"github.com/pion/interceptor/pkg/nack"
"github.com/pion/rtcp"
"github.com/pion/rtp"
)
const (
listenPort = 6420
mtu = 1500
ssrc = 5000
)
func main() {
go sendRoutine()
receiveRoutine()
}
func receiveRoutine() {
serverAddr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf("127.0.0.1:%d", listenPort))
if err != nil {
panic(err)
}
conn, err := net.ListenUDP("udp4", serverAddr)
if err != nil {
panic(err)
}
// Create NACK Generator
generatorFactory, err := nack.NewGeneratorInterceptor()
if err != nil {
panic(err)
}
generator, err := generatorFactory.NewInterceptor("")
if err != nil {
panic(err)
}
// Create our interceptor chain with just a NACK Generator
chain := interceptor.NewChain([]interceptor.Interceptor{generator})
// Create the writer just for a single SSRC stream
// this is a callback that is fired everytime a RTP packet is ready to be sent
streamReader := chain.BindRemoteStream(&interceptor.StreamInfo{
SSRC: ssrc,
RTCPFeedback: []interceptor.RTCPFeedback{{Type: "nack", Parameter: ""}},
}, interceptor.RTPReaderFunc(func(b []byte, _ interceptor.Attributes) (int, interceptor.Attributes, error) { return len(b), nil, nil }))
for rtcpBound, buffer := false, make([]byte, mtu); ; {
i, addr, err := conn.ReadFrom(buffer)
if err != nil {
panic(err)
}
log.Println("Received RTP")
if _, _, err := streamReader.Read(buffer[:i], nil); err != nil {
panic(err)
}
// Set the interceptor wide RTCP Writer
// this is a callback that is fired everytime a RTCP packet is ready to be sent
if !rtcpBound {
chain.BindRTCPWriter(interceptor.RTCPWriterFunc(func(pkts []rtcp.Packet, _ interceptor.Attributes) (int, error) {
buf, err := rtcp.Marshal(pkts)
if err != nil {
return 0, err
}
return conn.WriteTo(buf, addr)
}))
rtcpBound = true
}
}
}
func sendRoutine() {
// Dial our UDP listener that we create in receiveRoutine
serverAddr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf("127.0.0.1:%d", listenPort))
if err != nil {
panic(err)
}
conn, err := net.DialUDP("udp4", nil, serverAddr)
if err != nil {
panic(err)
}
// Create NACK Responder
responderFactory, err := nack.NewResponderInterceptor()
if err != nil {
panic(err)
}
responder, err := responderFactory.NewInterceptor("")
if err != nil {
panic(err)
}
// Create our interceptor chain with just a NACK Responder.
chain := interceptor.NewChain([]interceptor.Interceptor{responder})
// Set the interceptor wide RTCP Reader
// this is a handle to send NACKs back into the interceptor.
rtcpReader := chain.BindRTCPReader(interceptor.RTCPReaderFunc(func(in []byte, _ interceptor.Attributes) (int, interceptor.Attributes, error) {
return len(in), nil, nil
}))
// Create the writer just for a single SSRC stream
// this is a callback that is fired everytime a RTP packet is ready to be sent
streamWriter := chain.BindLocalStream(&interceptor.StreamInfo{
SSRC: ssrc,
RTCPFeedback: []interceptor.RTCPFeedback{{Type: "nack", Parameter: ""}},
}, interceptor.RTPWriterFunc(func(header *rtp.Header, payload []byte, attributes interceptor.Attributes) (int, error) {
headerBuf, err := header.Marshal()
if err != nil {
panic(err)
}
return conn.Write(append(headerBuf, payload...))
}))
// Read RTCP packets sent by receiver and pass into Interceptor
go func() {
for rtcpBuf := make([]byte, mtu); ; {
i, err := conn.Read(rtcpBuf)
if err != nil {
panic(err)
}
log.Println("Received NACK")
if _, _, err = rtcpReader.Read(rtcpBuf[:i], nil); err != nil {
panic(err)
}
}
}()
for sequenceNumber := uint16(0); ; sequenceNumber++ {
// Send a RTP packet with a Payload of 0x0, 0x1, 0x2
if _, err := streamWriter.Write(&rtp.Header{
Version: 2,
SSRC: ssrc,
SequenceNumber: sequenceNumber,
}, []byte{0x0, 0x1, 0x2}, nil); err != nil {
fmt.Println(err)
}
time.Sleep(time.Millisecond * 200)
}
}
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