split RTP packet handling from data handling (#2337)

internal/formatprocessor/generic.go

@@ -28,29 +28,32 @@ func newGeneric(
 	}, nil
 }
 
-func (t *formatProcessorGeneric) Process(u unit.Unit, _ bool) error {
-	tunit := u.(*unit.Generic)
-
-	pkt := tunit.RTPPackets[0]
-
-	// remove padding
-	pkt.Header.Padding = false
-	pkt.PaddingSize = 0
-
-	if pkt.MarshalSize() > t.udpMaxPayloadSize {
-		return fmt.Errorf("payload size (%d) is greater than maximum allowed (%d)",
-			pkt.MarshalSize(), t.udpMaxPayloadSize)
-	}
-
-	return nil
+func (t *formatProcessorGeneric) ProcessUnit(_ unit.Unit) error {
+	return fmt.Errorf("using a generic unit without RTP is not supported")
 }
 
-func (t *formatProcessorGeneric) UnitForRTPPacket(pkt *rtp.Packet, ntp time.Time, pts time.Duration) Unit {
-	return &unit.Generic{
+func (t *formatProcessorGeneric) ProcessRTPPacket(
+	pkt *rtp.Packet,
+	ntp time.Time,
+	pts time.Duration,
+	_ bool,
+) (Unit, error) {
+	u := &unit.Generic{
 		Base: unit.Base{
 			RTPPackets: []*rtp.Packet{pkt},
 			NTP:        ntp,
 			PTS:        pts,
 		},
 	}
+
+	// remove padding
+	pkt.Header.Padding = false
+	pkt.PaddingSize = 0
+
+	if pkt.MarshalSize() > t.udpMaxPayloadSize {
+		return nil, fmt.Errorf("payload size (%d) is greater than maximum allowed (%d)",
+			pkt.MarshalSize(), t.udpMaxPayloadSize)
+	}
+
+	return u, nil
 }