main.go

package main

import (
	"fmt"
	"math/rand"
	"os"
	"time"

	"github.com/pion/webrtc/v2"
	"github.com/pion/webrtc/v2/pkg/media"
	"github.com/pion/webrtc/v2/pkg/media/ivfreader"

	"github.com/pion/webrtc/v2/examples/internal/signal"
)

func main() {
	// Wait for the offer to be pasted
	offer := webrtc.SessionDescription{}
	signal.Decode(signal.MustReadStdin(), &offer)

	// We make our own mediaEngine so we can place the sender's codecs in it.  This because we must use the
	// dynamic media type from the sender in our answer. This is not required if we are the offerer
	mediaEngine := webrtc.MediaEngine{}
	err := mediaEngine.PopulateFromSDP(offer)
	if err != nil {
		panic(err)
	}

	// Search for VP8 Payload type. If the offer doesn't support VP8 exit since
	// since they won't be able to decode anything we send them
	var payloadType uint8
	for _, videoCodec := range mediaEngine.GetCodecsByKind(webrtc.RTPCodecTypeVideo) {
		if videoCodec.Name == "VP8" {
			payloadType = videoCodec.PayloadType
			break
		}
	}
	if payloadType == 0 {
		panic("Remote peer does not support VP8")
	}

	// Create a new RTCPeerConnection
	api := webrtc.NewAPI(webrtc.WithMediaEngine(mediaEngine))
	peerConnection, err := api.NewPeerConnection(webrtc.Configuration{
		ICEServers: []webrtc.ICEServer{
			{
				URLs: []string{"stun:stun.l.google.com:19302"},
			},
		},
	})
	if err != nil {
		panic(err)
	}

	// Create a video track
	videoTrack, err := peerConnection.NewTrack(payloadType, rand.Uint32(), "video", "pion")
	if err != nil {
		panic(err)
	}
	if _, err = peerConnection.AddTrack(videoTrack); err != nil {
		panic(err)
	}

	go func() {
		// Open a IVF file and start reading using our IVFReader
		file, ivfErr := os.Open("output.ivf")
		if ivfErr != nil {
			panic(ivfErr)
		}

		ivf, header, ivfErr := ivfreader.NewWith(file)
		if ivfErr != nil {
			panic(ivfErr)
		}

		// Send our video file frame at a time. Pace our sending so we send it at the same speed it should be played back as.
		// This isn't required since the video is timestamped, but we will such much higher loss if we send all at once.
		sleepTime := time.Millisecond * time.Duration((float32(header.TimebaseNumerator)/float32(header.TimebaseDenominator))*1000)
		for {
			frame, _, ivfErr := ivf.ParseNextFrame()
			if ivfErr != nil {
				panic(ivfErr)
			}

			time.Sleep(sleepTime)
			if ivfErr = videoTrack.WriteSample(media.Sample{Data: frame, Samples: 90000}); ivfErr != nil {
				panic(ivfErr)
			}
		}
	}()

	// Set the handler for ICE connection state
	// This will notify you when the peer has connected/disconnected
	peerConnection.OnICEConnectionStateChange(func(connectionState webrtc.ICEConnectionState) {
		fmt.Printf("Connection State has changed %s \n", connectionState.String())
	})

	// Set the remote SessionDescription
	if err = peerConnection.SetRemoteDescription(offer); err != nil {
		panic(err)
	}

	// Create answer
	answer, err := peerConnection.CreateAnswer(nil)
	if err != nil {
		panic(err)
	}

	// Sets the LocalDescription, and starts our UDP listeners
	if err = peerConnection.SetLocalDescription(answer); err != nil {
		panic(err)
	}

	// Output the answer in base64 so we can paste it in browser
	fmt.Println(signal.Encode(answer))

	// Block forever
	select {}
}