From 75b1e0887483595a35b3abdd75c71ebc51e142c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miroslav=20=C5=A0ediv=C3=BD?= <sedivy.miro@gmail.com>
Date: Sun, 28 Nov 2021 23:16:26 +0100
Subject: [PATCH] virtual microphone OnTrack.

---
 internal/webrtc/manager.go | 68 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/internal/webrtc/manager.go b/internal/webrtc/manager.go
index 9a8da87e..db1a3570 100644
--- a/internal/webrtc/manager.go
+++ b/internal/webrtc/manager.go
@@ -5,10 +5,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/pion/rtcp"
 	"github.com/pion/webrtc/v3"
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 
+	"demodesk/neko/internal/capture/gst"
 	"demodesk/neko/internal/config"
 	"demodesk/neko/internal/types"
 	"demodesk/neko/internal/types/codec"
@@ -155,8 +157,70 @@ func (manager *WebRTCManagerCtx) CreatePeer(session types.Session, videoID strin
 		iceTrickle: manager.config.ICETrickle,
 	}
 
-	connection.OnTrack(func(tr *webrtc.TrackRemote, r *webrtc.RTPReceiver) {
-		logger.Info().Interface("track", tr).Interface("receiver", r).Msg("got remote track")
+	connection.OnTrack(func(track *webrtc.TrackRemote, receiver *webrtc.RTPReceiver) {
+		// if we did not get audio
+		if track.Kind() != webrtc.RTPCodecTypeAudio {
+			logger.Warn().Msg("got remote track, but not audio")
+			return
+		}
+
+		codecName := strings.Split(track.Codec().RTPCodecCapability.MimeType, "/")[1]
+
+		logger.Info().
+			Str("stream-id", track.StreamID()).
+			Str("id", track.ID()).
+			Str("rid", track.RID()).
+			Str("codec", codecName).
+			Uint8("payload-type", uint8(track.PayloadType())).
+			Msgf("received new track")
+
+		pipelineStr := "appsrc format=time is-live=true do-timestamp=true name=src"
+
+		//add appropriate decoder
+		switch strings.ToLower(codecName) {
+		case "opus":
+			pipelineStr += fmt.Sprintf(" ! application/x-rtp, payload=%d, encoding-name=OPUS ! rtpopusdepay ! decodebin", track.PayloadType())
+		case "g722":
+			pipelineStr += " ! application/x-rtp clock-rate=8000 ! rtpg722depay ! decodebin"
+		default:
+			logger.Panic().Msgf("Unhandled codec %s", codecName)
+		}
+
+		pipelineStr += " ! pulsesink device=audio_input"
+		logger.Info().Str("pipeline", pipelineStr).Msg("create pipeline")
+
+		pipeline, err := gst.CreatePipeline(pipelineStr)
+		if err != nil {
+			logger.Err(err).Str("pipeline", pipelineStr).Msg("unable to create pipeline")
+			return
+		}
+
+		pipeline.Play()
+		defer pipeline.Stop()
+
+		// Send a PLI on an interval so that the publisher is pushing a keyframe every rtcpPLIInterval
+		ticker := time.NewTicker(time.Second * 3)
+		defer ticker.Stop()
+
+		go func() {
+			for range ticker.C {
+				rtcpSendErr := connection.WriteRTCP([]rtcp.Packet{&rtcp.PictureLossIndication{MediaSSRC: uint32(track.SSRC())}})
+				if rtcpSendErr != nil {
+					fmt.Println(rtcpSendErr)
+				}
+			}
+		}()
+
+		buf := make([]byte, 1400)
+		for {
+			i, _, err := track.Read(buf)
+			if err != nil {
+				logger.Warn().Err(err).Msg("failed read from pipeline")
+				break
+			}
+
+			pipeline.Push("src", buf[:i])
+		}
 	})
 
 	connection.OnDataChannel(func(dc *webrtc.DataChannel) {