avoid ReceivedPacketsDropped for first received packet

added firstMessageReceived to the Particpant struct. Set to false when packet is receievd. Only when USE_EXT_CALLBACKS is defined
lathoub · Jan 16, 2021 · 84f3dca · 84f3dca
1 parent 3504cfc
commit 84f3dca
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Showing 2 changed files with 10 additions and 8 deletions.
diff --git a/src/AppleMIDI.hpp b/src/AppleMIDI.hpp
@@ -1011,21 +1011,21 @@ void AppleMIDISession<UdpClass, Settings, Platform>::ReceivedRtp(const Rtp_t& rt
 #ifdef USE_EXT_CALLBACKS
         auto offset = (rtp.timestamp - pParticipant->offsetEstimate);
         auto latency = (int32_t)(rtpMidiClock.Now() - offset);
-#endif
-        if (rtp.sequenceNr - pParticipant->receiveSequenceNr - 1 != 0) {
 
-#ifdef USE_EXT_CALLBACKS
+        if (pParticipant->firstMessageReceived == false 
+        && rtp.sequenceNr - pParticipant->receiveSequenceNr - 1 != 0) {
+             // avoids first message to generate sequence exception
+             // as we do not know the last sequenceNr received.
+            pParticipant->firstMessageReceived = false;
             if (nullptr != _exceptionCallback)
                 _exceptionCallback(ssrc, ReceivedPacketsDropped, rtp.sequenceNr - pParticipant->receiveSequenceNr - 1);
-#endif
         }
 
-        pParticipant->receiveSequenceNr = rtp.sequenceNr;
-
-#ifdef USE_EXT_CALLBACKS
         if (nullptr != _receivedRtpCallback)
             _receivedRtpCallback(pParticipant->ssrc, rtp, latency);
 #endif
+
+        pParticipant->receiveSequenceNr = rtp.sequenceNr;
     }
     else
     {

diff --git a/src/AppleMIDI_Participant.h b/src/AppleMIDI_Participant.h
@@ -18,7 +18,8 @@ struct Participant
     bool            doReceiverFeedback = false;
 
     uint16_t        sendSequenceNr = random(1, UINT16_MAX); // http://www.rfc-editor.org/rfc/rfc6295.txt , 2.1.  RTP Header
-    uint16_t        receiveSequenceNr;
+    uint16_t        receiveSequenceNr = 0;
+
     unsigned long   lastSyncExchangeTime;
 
 #ifdef APPLEMIDI_INITIATOR
@@ -33,6 +34,7 @@ struct Participant
 #endif
 
 #ifdef USE_EXT_CALLBACKS
+    bool            firstMessageReceived = true;
     uint32_t        offsetEstimate;
 #endif