Immediately report a lost frame if we find a discontinuity in the frame indices

src/RtpVideoQueue.c

@@ -13,8 +13,7 @@ void RtpvInitializeQueue(PRTP_VIDEO_QUEUE queue) {
     reed_solomon_init();
     memset(queue, 0, sizeof(*queue));
 
-    queue->currentFrameNumber = UINT16_MAX;
+    queue->currentFrameNumber = 1;
-
     queue->multiFecCapable = APP_VERSION_AT_LEAST(7, 1, 431);
 }
 
@@ -542,7 +541,10 @@ int RtpvAddPacket(PRTP_VIDEO_QUEUE queue, PRTP_PACKET packet, int length, PRTPV_
                     purgeListEntries(&queue->completedFecBlockList);
 
                     // Notify the host of the loss of this frame
+                    if (!queue->reportedLostFrame) {
                         notifyFrameLost(queue->currentFrameNumber);
+                        queue->reportedLostFrame = true;
+                    }
 
                     queue->currentFrameNumber++;
                     queue->multiFecCurrentBlockNumber = 0;
@@ -572,7 +574,10 @@ int RtpvAddPacket(PRTP_VIDEO_QUEUE queue, PRTP_PACKET packet, int length, PRTPV_
             purgeListEntries(&queue->completedFecBlockList);
 
             // Notify the host of the loss of this frame
+            if (!queue->reportedLostFrame) {
                 notifyFrameLost(queue->currentFrameNumber);
+                queue->reportedLostFrame = true;
+            }
 
             // We dropped a block of this frame, so we must skip to the next one.
             queue->currentFrameNumber = nvPacket->frameIndex + 1;
@@ -588,6 +593,22 @@ int RtpvAddPacket(PRTP_VIDEO_QUEUE queue, PRTP_PACKET packet, int length, PRTPV_
             purgeListEntries(&queue->completedFecBlockList);
         }
 
+        // If the frame numbers are not contiguous, the network dropped an entire frame.
+        // The check here looks weird, but that's because we increment the frame number
+        // after successfully processing a frame.
+        if (queue->currentFrameNumber != nvPacket->frameIndex) {
+            LC_ASSERT(queue->currentFrameNumber < nvPacket->frameIndex);
+
+            // If the frame immediately preceding this one was lost, we may have already
+            // reported it using our predictive RFI logic. Don't report it again.
+            if (queue->currentFrameNumber + 1 != nvPacket->frameIndex || !queue->reportedLostFrame) {
+                // NB: We only have to notify for the most recent lost frame, since
+                // the depacketizer will report the RFI range starting at the last
+                // frame it saw.
+                notifyFrameLost(nvPacket->frameIndex - 1);
+            }
+        }
+
         queue->currentFrameNumber = nvPacket->frameIndex;
 
         // Tell the control stream logic about this frame, even if we don't end up