From 884b8d0a950a47496fb96cd5d9a32c6745ba590a Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Wed, 5 Sep 2018 12:04:39 -0700
Subject: [PATCH] Additional fixes for corrupt FEC recovery handling

---
 src/RtpFecQueue.c       |  2 +-
 src/SdpGenerator.c      |  4 ++++
 src/VideoDepacketizer.c | 24 +++++++++++++++++-------
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/RtpFecQueue.c b/src/RtpFecQueue.c
index ff60d70..d3782ab 100644
--- a/src/RtpFecQueue.c
+++ b/src/RtpFecQueue.c
@@ -72,11 +72,11 @@ static int queuePacket(PRTP_FEC_QUEUE queue, PRTPFEC_QUEUE_ENTRY newEntry, int h
 }
 
 #define PACKET_RECOVERY_FAILURE()                     \
-    free(packets[i]);                                 \
     ret = -1;                                         \
     Limelog("FEC recovery returned corrupt packet %d" \
             " (frame %d)", rtpPacket->sequenceNumber, \
             queue->currentFrameNumber);               \
+    free(packets[i]);                                 \
     continue
 
 // Returns 0 if the frame is completely constructed
diff --git a/src/SdpGenerator.c b/src/SdpGenerator.c
index 54b656b..f2d0b39 100644
--- a/src/SdpGenerator.c
+++ b/src/SdpGenerator.c
@@ -162,6 +162,10 @@ static int addGen5Options(PSDP_OPTION* head) {
         err |= addAttributeString(head, "x-nv-vqos[0].fec.repairPercent", "5");
     }
 
+    // Recovery mode can cause the FEC percentage to change mid-frame, which
+    // breaks many assumptions in RTP FEC queue.
+    err |= addAttributeString(head, "x-nv-general.enableRecoveryMode", "0");
+
     return err;
 }
 
diff --git a/src/VideoDepacketizer.c b/src/VideoDepacketizer.c
index bafcd41..91899b0 100644
--- a/src/VideoDepacketizer.c
+++ b/src/VideoDepacketizer.c
@@ -471,9 +471,23 @@ void processRtpPayload(PNV_VIDEO_PACKET videoPacket, int length, unsigned long l
 
     streamPacketIndex = videoPacket->streamPacketIndex;
     
-    // The packets and frames must be in sequence from the FEC queue
-    LC_ASSERT(!isBefore24(streamPacketIndex, U24(lastPacketInStream + 1)));
-    LC_ASSERT(!isBefore32(frameIndex, nextFrameNumber));
+    // Drop packets from a previously corrupt frame
+    if (isBefore32(frameIndex, nextFrameNumber)) {
+        return;
+    }
+
+    // The FEC queue can sometimes recover corrupt frames (see comments in RtpFecQueue).
+    // It almost always detects them before they get to us, but in case it doesn't
+    // the streamPacketIndex not matching correctly should find nearly all of the rest.
+    if (isBefore24(streamPacketIndex, U24(lastPacketInStream + 1)) ||
+            (!firstPacket && streamPacketIndex != U24(lastPacketInStream + 1))) {
+        Limelog("Depacketizer detected corrupt frame: %d", frameIndex);
+        decodingFrame = 0;
+        nextFrameNumber = frameIndex + 1;
+        waitingForNextSuccessfulFrame = 1;
+        dropFrameState();
+        return;
+    }
 
     // Notify the listener of the latest frame we've seen from the PC
     connectionSawFrame(frameIndex);
@@ -502,10 +516,6 @@ void processRtpPayload(PNV_VIDEO_PACKET videoPacket, int length, unsigned long l
         firstPacketReceiveTime = receiveTimeMs;
     }
 
-    // This must be the first packet in a frame or be contiguous with the last
-    // packet received.
-    LC_ASSERT(firstPacket || streamPacketIndex == U24(lastPacketInStream + 1));
-
     lastPacketInStream = streamPacketIndex;
 
     // If this is the first packet, skip the frame header (if one exists)