WebRTC is registering to the audio-transcoded stream

transcoder/audio/audio.go

@@ -4,8 +4,9 @@ package audio
 import (
 	"bufio"
 	"fmt"
-	"io"
 	"log"
+	"math/rand"
+	"net"
 	"os/exec"
 	"strings"
 	"time"
@@ -84,20 +85,37 @@ func transcode(input, output *stream.Stream, cfg *Options) {
 	}
 
 	// Stop transcode
-	ffmpeg.Process.Kill()
+	_ = ffmpeg.Process.Kill()
+	_ = rawvideo.Close()
 }
 
 // Start a ffmpeg instance to convert stream into audio
-func startFFmpeg(in <-chan []byte, cfg *Options) (*exec.Cmd, *io.ReadCloser, error) {
+func startFFmpeg(in <-chan []byte, cfg *Options) (*exec.Cmd, *net.UDPConn, error) {
 	// TODO in a future release: remove FFMPEG dependency and transcode directly using the libopus API
 
 	// FIXME It seems impossible to get a RTP Packet from standard output.
 	// We need to find a clean solution, without waiting on UDP listeners.
+	// FIXME We should also not build RTP packets here.
+
+	port := 0
+	var udpListener *net.UDPConn
+	var err error
+	for {
+		port = rand.Intn(65535)
+		udpListener, err = net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: port})
+		if err != nil {
+			if strings.Contains(fmt.Sprintf("%s", err), "address already in use") {
+				continue
+			}
+			return nil, nil, err
+		}
+		break
+	}
 
 	bitrate := fmt.Sprintf("%dk", cfg.Bitrate)
 	// Use copy audio codec, assume for now that libopus is used by the streamer
 	ffmpegArgs := []string{"-hide_banner", "-loglevel", "error", "-i", "pipe:0",
-		"-vn", "-c:a", "copy", "-b:a", bitrate, "-f", "rtp", "pipe:1"}
+		"-vn", "-c:a", "copy", "-b:a", bitrate, "-f", "rtp", fmt.Sprintf("rtp://127.0.0.1:%d", port)}
 	ffmpeg := exec.Command("ffmpeg", ffmpegArgs...)
 
 	// Handle errors output
@@ -112,12 +130,6 @@ func startFFmpeg(in <-chan []byte, cfg *Options) (*exec.Cmd, *io.ReadCloser, err
 		}
 	}()
 
-	// Handle audio output
-	output, err := ffmpeg.StdoutPipe()
-	if err != nil {
-		return nil, nil, err
-	}
-
 	// Handle stream input
 	input, err := ffmpeg.StdinPipe()
 	if err != nil {
@@ -125,11 +137,11 @@ func startFFmpeg(in <-chan []byte, cfg *Options) (*exec.Cmd, *io.ReadCloser, err
 	}
 	go func() {
 		for data := range in {
-			input.Write(data)
+			_, _ = input.Write(data)
 		}
 	}()
 
 	// Start process
 	err = ffmpeg.Start()
-	return ffmpeg, &output, err
+	return ffmpeg, udpListener, err
 }