Add proxy example (#141) (#175)

* cleanup

* add proxy example

examples/proxy/client.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"log"
+	"sync"
+	"time"
+
+	"github.com/aler9/gortsplib/v2"
+	"github.com/aler9/gortsplib/v2/pkg/format"
+	"github.com/aler9/gortsplib/v2/pkg/media"
+	"github.com/aler9/gortsplib/v2/pkg/url"
+	"github.com/pion/rtp"
+)
+
+const (
+	existingStream = "rtsp://x.x.x.x:8554/mystream"
+	reconnectPause = 2 * time.Second
+)
+
+type client struct {
+	mutex  sync.RWMutex
+	stream *gortsplib.ServerStream
+}
+
+func newClient() *client {
+	c := &client{}
+
+	// start a separated routine
+	go c.run()
+
+	return c
+}
+
+func (c *client) run() {
+	for {
+		err := c.read()
+		log.Printf("ERR: %s\n", err)
+
+		time.Sleep(reconnectPause)
+	}
+}
+
+func (c *client) getStream() *gortsplib.ServerStream {
+	c.mutex.RLock()
+	defer c.mutex.RUnlock()
+	return c.stream
+}
+
+func (c *client) read() error {
+	rc := gortsplib.Client{}
+
+	// parse URL
+	u, err := url.Parse(existingStream)
+	if err != nil {
+		return err
+	}
+
+	// connect to the server
+	err = rc.Start(u.Scheme, u.Host)
+	if err != nil {
+		return err
+	}
+	defer rc.Close()
+
+	// find published medias
+	medias, baseURL, _, err := rc.Describe(u)
+	if err != nil {
+		return err
+	}
+
+	// setup all medias
+	err = rc.SetupAll(medias, baseURL)
+	if err != nil {
+		return err
+	}
+
+	// create a server stream
+	stream := gortsplib.NewServerStream(medias)
+	defer stream.Close()
+
+	log.Printf("stream is ready and can be read from the server at rtsp://localhost:8554/stream\n")
+
+	// make stream available by using getStream()
+	c.mutex.Lock()
+	c.stream = stream
+	c.mutex.Unlock()
+
+	defer func() {
+		// remove stream from getStream()
+		c.mutex.Lock()
+		c.stream = nil
+		c.mutex.Unlock()
+	}()
+
+	// called when a RTP packet arrives
+	rc.OnPacketRTPAny(func(medi *media.Media, forma format.Format, pkt *rtp.Packet) {
+		// route incoming packets to the server stream
+		stream.WritePacketRTP(medi, pkt)
+	})
+
+	// start playing
+	_, err = rc.Play(nil)
+	if err != nil {
+		return err
+	}
+
+	// wait until a fatal error
+	return rc.Wait()
+}