Fix sequencing errors that lead to drops in audio or video for potentially long periods under the right conditions

moonlight-common/src/com/limelight/nvstream/av/RtpReorderQueue.java

@@ -45,7 +45,7 @@ public class RtpReorderQueue {
 		
 		if (nextRtpSequenceNumber != Short.MAX_VALUE) {
 			// Don't queue packets we're already ahead of
-			if (seq < nextRtpSequenceNumber) {
+			if (SequenceHelper.isBeforeSigned(seq, nextRtpSequenceNumber, false)) {
 				return false;
 			}
 			
@@ -88,11 +88,15 @@ public class RtpReorderQueue {
 	}
 	
 	private RtpQueueEntry getEntryByLowestSeq() {
-		short nextSeq = Short.MAX_VALUE;
-		RtpQueueEntry lowestSeqEntry = null;
+		if (queue.isEmpty()) {
+			return null;
+		}
+		
+		RtpQueueEntry lowestSeqEntry = queue.getFirst();
+		short nextSeq = lowestSeqEntry.sequenceNumber;
 		
 		for (RtpQueueEntry entry : queue) {
-			if (entry.sequenceNumber < nextSeq) {
+			if (SequenceHelper.isBeforeSigned(entry.sequenceNumber, nextSeq, true)) {
 				lowestSeqEntry = entry;
 				nextSeq = entry.sequenceNumber;
 			}
@@ -140,7 +144,7 @@ public class RtpReorderQueue {
 	
 	public RtpQueueStatus addPacket(RtpPacketFields packet) {
 		if (nextRtpSequenceNumber != Short.MAX_VALUE &&
-			packet.getRtpSequenceNumber() < nextRtpSequenceNumber) {
+			SequenceHelper.isBeforeSigned(packet.getRtpSequenceNumber(), nextRtpSequenceNumber, false)) {
 			// Reject packets behind our current sequence number
 			return RtpQueueStatus.REJECTED;
 		}

moonlight-common/src/com/limelight/nvstream/av/SequenceHelper.java

@@ -0,0 +1,20 @@
+package com.limelight.nvstream.av;
+
+public class SequenceHelper {
+	public static boolean isBeforeSigned(int numA, int numB, boolean ambiguousCase) {
+		// This should be the common case for most callers
+		if (numA == numB) {
+			return false;
+		}
+		
+		// If numA and numB have the same signs,
+		// we can just do a regular comparison.
+		if ((numA < 0 && numB < 0) || (numA >= 0 && numB >= 0)) {
+			return numA < numB;
+		}
+		else {
+			// The sign switch is ambiguous
+			return ambiguousCase;
+		}
+	}
+}

moonlight-common/src/com/limelight/nvstream/av/audio/AudioDepacketizer.java

@@ -4,6 +4,7 @@ import com.limelight.LimeLog;
 import com.limelight.nvstream.av.ByteBufferDescriptor;
 import com.limelight.nvstream.av.PopulatedBufferList;
 import com.limelight.nvstream.av.RtpPacket;
+import com.limelight.nvstream.av.SequenceHelper;
 
 public class AudioDepacketizer {
 	
@@ -88,7 +89,7 @@ public class AudioDepacketizer {
 			
 			// Only tell the decoder if we got packets ahead of what we expected
 			// If the packet is behind the current sequence number, drop it
-			if (seq > (short)(lastSequenceNumber + 1)) {
+			if (!SequenceHelper.isBeforeSigned(seq, (short)(lastSequenceNumber + 1), false)) {
 				decodeData(null, 0, 0);
 			}
 			else {

moonlight-common/src/com/limelight/nvstream/av/video/VideoDepacketizer.java

@@ -7,6 +7,7 @@ import com.limelight.nvstream.av.ByteBufferDescriptor;
 import com.limelight.nvstream.av.DecodeUnit;
 import com.limelight.nvstream.av.ConnectionStatusListener;
 import com.limelight.nvstream.av.PopulatedBufferList;
+import com.limelight.nvstream.av.SequenceHelper;
 
 public class VideoDepacketizer {
 	
@@ -232,12 +233,12 @@ public class VideoDepacketizer {
 		
 		// Drop duplicates or re-ordered packets
 		int streamPacketIndex = packet.getStreamPacketIndex();
-		if (streamPacketIndex < (int)(lastPacketInStream + 1)) {
+		if (SequenceHelper.isBeforeSigned((short)streamPacketIndex, (short)(lastPacketInStream + 1), false)) {
 			return;
 		}
 		
 		// Drop packets from a previously completed frame
-		if (frameIndex < nextFrameNumber) {
+		if (SequenceHelper.isBeforeSigned(frameIndex, nextFrameNumber, false)) {
 			return;
 		}
 		
@@ -279,7 +280,7 @@ public class VideoDepacketizer {
 		// miss one in between
 		else if (firstPacket) {
 			// Make sure this is the next consecutive frame
-			if (nextFrameNumber < frameIndex) {
+			if (SequenceHelper.isBeforeSigned(nextFrameNumber, frameIndex, true)) {
 				LimeLog.warning("Network dropped an entire frame");
 				nextFrameNumber = frameIndex;
 				
@@ -287,7 +288,7 @@ public class VideoDepacketizer {
 				waitingForNextSuccessfulFrame = true;
 				dropAvcFrameState();
 			}
-			else if (nextFrameNumber > frameIndex){
+			else if (nextFrameNumber != frameIndex) {
 				// Duplicate packet or FEC dup
 				decodingFrame = false;
 				return;