From 4134ea3c23db6a5d9d7624237dcb382a91c4bbd4 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sat, 10 Jun 2017 15:42:51 -0700
Subject: [PATCH] Prevent the depacketizer from receiving parity packets

---
 src/RtpFecQueue.c | 24 +++++++++++++++++++++---
 src/RtpFecQueue.h |  1 +
 src/VideoStream.c |  1 -
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/RtpFecQueue.c b/src/RtpFecQueue.c
index 07eebf9..8066e4d 100644
--- a/src/RtpFecQueue.c
+++ b/src/RtpFecQueue.c
@@ -28,7 +28,7 @@ void RtpfCleanupQueue(PRTP_FEC_QUEUE queue) {
 }
 
 // newEntry is contained within the packet buffer so we free the whole entry by freeing entry->packet
-static int queuePacket(PRTP_FEC_QUEUE queue, PRTPFEC_QUEUE_ENTRY newEntry, int head, PRTP_PACKET packet, int length) {
+static int queuePacket(PRTP_FEC_QUEUE queue, PRTPFEC_QUEUE_ENTRY newEntry, int head, PRTP_PACKET packet, int length, int isParity) {
     PRTPFEC_QUEUE_ENTRY entry;
     
     LC_ASSERT(!isBefore(packet->sequenceNumber, queue->nextRtpSequenceNumber));
@@ -45,6 +45,7 @@ static int queuePacket(PRTP_FEC_QUEUE queue, PRTPFEC_QUEUE_ENTRY newEntry, int h
     
     newEntry->packet = packet;
     newEntry->length = length;
+    newEntry->isParity = isParity;
     newEntry->prev = NULL;
     newEntry->next = NULL;
 
@@ -170,7 +171,8 @@ cleanup_packets:
                 // discarded by decoders. It's not safe to strip all zero padding because
                 // it may be a legitimate part of the H.264 bytestream.
 
-                queuePacket(queue, queueEntry, 0, rtpPacket, StreamConfig.packetSize + dataOffset);
+                LC_ASSERT(isBefore(rtpPacket->sequenceNumber, queue->bufferFirstParitySequenceNumber));                
+                queuePacket(queue, queueEntry, 0, rtpPacket, StreamConfig.packetSize + dataOffset, 0);
             } else if (packets[i] != NULL) {
                 free(packets[i]);
             }
@@ -264,7 +266,7 @@ int RtpfAddPacket(PRTP_FEC_QUEUE queue, PRTP_PACKET packet, int length, PRTPFEC_
         queue->bufferHighestSequenceNumber = packet->sequenceNumber;
     }
     
-    if (!queuePacket(queue, packetEntry, 0, packet, length)) {
+    if (!queuePacket(queue, packetEntry, 0, packet, length, !isBefore(packet->sequenceNumber, queue->bufferFirstParitySequenceNumber))) {
         return RTPF_RET_REJECTED;
     }
     else {
@@ -307,6 +309,22 @@ PRTPFEC_QUEUE_ENTRY RtpfGetQueuedPacket(PRTP_FEC_QUEUE queue) {
     unsigned int lowestRtpSequenceNumber = UINT16_MAX;
     
     while (entry != NULL) {
+        // Never return parity packets
+        if (entry->isParity) {
+            PRTPFEC_QUEUE_ENTRY parityEntry = entry;
+            
+            // Skip this entry
+            entry = parityEntry->next;
+            
+            // Remove this entry
+            removeEntry(queue, parityEntry);
+            
+            // Free the entry and packet
+            free(parityEntry->packet);
+            
+            continue;
+        }
+        
         if (queuedEntry == NULL || isBefore(entry->packet->sequenceNumber, lowestRtpSequenceNumber)) {
             lowestRtpSequenceNumber = entry->packet->sequenceNumber;
             queuedEntry = entry;
diff --git a/src/RtpFecQueue.h b/src/RtpFecQueue.h
index 2bcf0a5..93044e4 100644
--- a/src/RtpFecQueue.h
+++ b/src/RtpFecQueue.h
@@ -5,6 +5,7 @@
 typedef struct _RTPFEC_QUEUE_ENTRY {
     PRTP_PACKET packet;
     int length;
+    int isParity;
 
     struct _RTPFEC_QUEUE_ENTRY* next;
     struct _RTPFEC_QUEUE_ENTRY* prev;
diff --git a/src/VideoStream.c b/src/VideoStream.c
index f49ef09..bd14cdb 100644
--- a/src/VideoStream.c
+++ b/src/VideoStream.c
@@ -65,7 +65,6 @@ static void ReceiveThreadProc(void* context) {
     int bufferSize, receiveSize;
     char* buffer;
     int queueStatus;
-    int length;
     PRTPFEC_QUEUE_ENTRY queueEntry;
 
     receiveSize = StreamConfig.packetSize + MAX_RTP_HEADER_SIZE;