add new example client-read-format-mpeg4audio-save-to-disk (#235)

examples/client-read-format-mpeg4audio-save-to-disk/main.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"log"
+
+	"github.com/bluenviron/gortsplib/v3"
+	"github.com/bluenviron/gortsplib/v3/pkg/formats"
+	"github.com/bluenviron/gortsplib/v3/pkg/url"
+	"github.com/pion/rtp"
+)
+
+// This example shows how to
+// 1. connect to a RTSP server
+// 2. check if there's an MPEG4-audio media
+// 3. save the content of the media into a file in MPEG-TS format
+
+func main() {
+	c := gortsplib.Client{}
+
+	// parse URL
+	u, err := url.Parse("rtsp://localhost:8554/mystream")
+	if err != nil {
+		panic(err)
+	}
+
+	// connect to the server
+	err = c.Start(u.Scheme, u.Host)
+	if err != nil {
+		panic(err)
+	}
+	defer c.Close()
+
+	// find published medias
+	medias, baseURL, _, err := c.Describe(u)
+	if err != nil {
+		panic(err)
+	}
+
+	// find the MPEG4-audio media and format
+	var forma *formats.MPEG4Audio
+	medi := medias.FindFormat(&forma)
+	if medi == nil {
+		panic("media not found")
+	}
+
+	// setup RTP/MPEG4-audio -> MPEG4-audio decoder
+	rtpDec := forma.CreateDecoder()
+
+	// setup MPEG4-audio -> MPEG-TS muxer
+	mpegtsMuxer, err := newMPEGTSMuxer(forma.Config)
+	if err != nil {
+		panic(err)
+	}
+
+	// setup a single media
+	_, err = c.Setup(medi, baseURL, 0, 0)
+	if err != nil {
+		panic(err)
+	}
+
+	// called when a RTP packet arrives
+	c.OnPacketRTP(medi, forma, func(pkt *rtp.Packet) {
+		// extract access units from RTP packets
+		aus, pts, err := rtpDec.Decode(pkt)
+		if err != nil {
+			log.Printf("ERR: %v", err)
+			return
+		}
+
+		for _, au := range aus {
+			// encode the access unit into MPEG-TS
+			mpegtsMuxer.encode(au, pts)
+		}
+	})
+
+	// start playing
+	_, err = c.Play(nil)
+	if err != nil {
+		panic(err)
+	}
+
+	// wait until a fatal error
+	panic(c.Wait())
+}