Implementation of opuswriter

- Implemented a common "Writer" interface
- Made IVFWriter compliant to the new interface
- Implemented an OGG Opus writer
- Updated the save-file example
- Updated janus-gateway/streaming example
- Wrote a few unit tests for opus-writer
- Wrote a few unit tests for ivf-writer
- Fixed filenames
- Improved API to allow tests using an io.Writer

examples/save-to-disk/main.go

@@ -6,13 +6,33 @@ import (
 
 	"github.com/pions/rtcp"
 	"github.com/pions/webrtc"
+	"github.com/pions/webrtc/pkg/media"
 	"github.com/pions/webrtc/pkg/media/ivfwriter"
+	"github.com/pions/webrtc/pkg/media/opuswriter"
 
 	"github.com/pions/webrtc/examples/internal/signal"
 )
 
-func main() {
+func saveToDisk(i media.Writer, track *webrtc.Track) {
+	defer func() {
+		if err := i.Close(); err != nil {
+			panic(err)
+		}
+	}()
 
+	for {
+		packet, err := track.ReadRTP()
+		if err != nil {
+			panic(err)
+		}
+
+		if err := i.AddPacket(packet); err != nil {
+			panic(err)
+		}
+	}
+}
+
+func main() {
 	// Create a MediaEngine object to configure the supported codec
 	m := webrtc.MediaEngine{}
 
@@ -49,31 +69,28 @@ func main() {
 		go func() {
 			ticker := time.NewTicker(time.Second * 3)
 			for range ticker.C {
-				err := peerConnection.SendRTCP(&rtcp.PictureLossIndication{MediaSSRC: track.SSRC()})
-				if err != nil {
-					fmt.Println(err)
+				errSend := peerConnection.SendRTCP(&rtcp.PictureLossIndication{MediaSSRC: track.SSRC()})
+				if errSend != nil {
+					fmt.Println(errSend)
 				}
 			}
 		}()
 
-		if track.Codec().Name == webrtc.VP8 {
+		codec := track.Codec()
+		if codec.Name == webrtc.Opus {
+			fmt.Println("Got Opus track, saving to disk as output.opus")
+			i, err := opuswriter.New("output.opus", codec.ClockRate, codec.Channels)
+			if err != nil {
+				panic(err)
+			}
+			saveToDisk(i, track)
+		} else if codec.Name == webrtc.VP8 {
 			fmt.Println("Got VP8 track, saving to disk as output.ivf")
 			i, err := ivfwriter.New("output.ivf")
 			if err != nil {
 				panic(err)
 			}
-
-			for {
-				packet, err := track.ReadRTP()
-				if err != nil {
-					panic(err)
-				}
-
-				err = i.AddPacket(packet)
-				if err != nil {
-					panic(err)
-				}
-			}
+			saveToDisk(i, track)
 		}
 	})