align PacketPTS() and PacketNTP(); add example (#374)

server_stream_format.go

@@ -1,11 +1,54 @@
 package gortsplib
 
 import (
+	"time"
+
+	"github.com/pion/rtcp"
+	"github.com/pion/rtp"
+
 	"github.com/bluenviron/gortsplib/v4/pkg/format"
 	"github.com/bluenviron/gortsplib/v4/pkg/rtcpsender"
 )
 
 type serverStreamFormat struct {
+	sm         *serverStreamMedia
 	format     format.Format
 	rtcpSender *rtcpsender.RTCPSender
 }
+
+func newServerStreamFormat(sm *serverStreamMedia, forma format.Format) *serverStreamFormat {
+	sf := &serverStreamFormat{
+		sm:     sm,
+		format: forma,
+	}
+
+	sf.rtcpSender = rtcpsender.New(
+		forma.ClockRate(),
+		sm.st.s.senderReportPeriod,
+		sm.st.s.timeNow,
+		func(pkt rtcp.Packet) {
+			if !sm.st.s.DisableRTCPSenderReports {
+				sm.st.WritePacketRTCP(sm.media, pkt) //nolint:errcheck
+			}
+		},
+	)
+
+	return sf
+}
+
+func (sf *serverStreamFormat) writePacketRTP(byts []byte, pkt *rtp.Packet, ntp time.Time) {
+	sf.rtcpSender.ProcessPacket(pkt, ntp, sf.format.PTSEqualsDTS(pkt))
+
+	// send unicast
+	for r := range sf.sm.st.activeUnicastReaders {
+		sm, ok := r.setuppedMedias[sf.sm.media]
+		if ok {
+			sm.writePacketRTP(byts)
+		}
+	}
+
+	// send multicast
+	if sf.sm.multicastWriter != nil {
+		sf.sm.multicastWriter.writePacketRTP(byts)
+	}
+}