Merge pull request jitsi#26 from bbaldino/rtx-cleanup

Rtx cleanup

src/main/kotlin/org/jitsi/nlj/rtp/RtxPacket.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright @ 2018 - present 8x8, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jitsi.nlj.rtp
+
+import org.jitsi.nlj.util.shiftPayloadLeft
+import org.jitsi.nlj.util.shiftPayloadRight
+import org.jitsi.rtp.extensions.bytearray.putShort
+import org.jitsi.rtp.rtp.RtpPacket
+import org.jitsi.rtp.util.getShortAsInt
+
+/**
+ * https://tools.ietf.org/html/rfc4588#section-4
+ *
+ *  0                   1                   2                   3
+ *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |                         RTP Header                            |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |            OSN                |                               |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
+ * |                  Original RTP Packet Payload                  |
+ * |                                                               |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+class RtxPacket {
+    companion object {
+        fun getOriginalSequenceNumber(rtxPacket: RtpPacket): Int =
+            rtxPacket.buffer.getShortAsInt(rtxPacket.offset + rtxPacket.headerLength)
+
+        /**
+         * Removes the original sequence number by shifting the payload 2 bytes
+         * to the left and reducing the length of the packet by 2
+         */
+        fun removeOriginalSequenceNumber(rtxPacket: RtpPacket) {
+            rtxPacket.shiftPayloadLeft(2)
+            rtxPacket.length = rtxPacket.length - 2
+        }
+
+        fun addOriginalSequenceNumber(rtpPacket: RtpPacket) {
+            rtpPacket.shiftPayloadRight(2)
+            rtpPacket.length = rtpPacket.length + 2
+            rtpPacket.buffer.putShort(rtpPacket.offset + rtpPacket.headerLength, rtpPacket.sequenceNumber.toShort())
+        }
+    }
+}

src/main/kotlin/org/jitsi/nlj/transform/node/incoming/RtxHandler.kt

@@ -21,6 +21,7 @@ import org.jitsi.nlj.RtpPayloadTypeAddedEvent
 import org.jitsi.nlj.RtpPayloadTypeClearEvent
 import org.jitsi.nlj.SsrcAssociationEvent
 import org.jitsi.nlj.format.RtxPayloadType
+import org.jitsi.nlj.rtp.RtxPacket
 import org.jitsi.nlj.rtp.SsrcAssociationType
 import org.jitsi.nlj.stats.NodeStatsBlock
 import org.jitsi.nlj.transform.node.TransformerNode
@@ -70,13 +71,12 @@ class RtxHandler : TransformerNode("RTX handler") {
                 return null
             }
 
-            val originalSeqNum = rtpPacket.originalSequenceNumber
+            val originalSeqNum = RtxPacket.getOriginalSequenceNumber(rtpPacket)
             val originalPt = associatedPayloadTypes[rtpPacket.payloadType.toPositiveInt()]!!
             val originalSsrc = associatedSsrcs[rtpPacket.ssrc]!!
 
             // Move the payload 2 bytes to the left
-            rtpPacket.shiftPayloadLeft(2)
-            rtpPacket.length = rtpPacket.length - 2
+            RtxPacket.removeOriginalSequenceNumber(rtpPacket)
             rtpPacket.sequenceNumber = originalSeqNum
             rtpPacket.payloadType = originalPt
             rtpPacket.ssrc = originalSsrc

src/main/kotlin/org/jitsi/nlj/transform/node/outgoing/RetransmissionSender.kt

@@ -21,6 +21,7 @@ import org.jitsi.nlj.RtpPayloadTypeAddedEvent
 import org.jitsi.nlj.RtpPayloadTypeClearEvent
 import org.jitsi.nlj.SsrcAssociationEvent
 import org.jitsi.nlj.format.RtxPayloadType
+import org.jitsi.nlj.rtp.RtxPacket
 import org.jitsi.nlj.rtp.SsrcAssociationType
 import org.jitsi.nlj.stats.NodeStatsBlock
 import org.jitsi.nlj.transform.node.TransformerNode
@@ -71,9 +72,7 @@ class RetransmissionSender : TransformerNode("Retransmission sender") {
         // in the map, get the value and increment it by 1
         val rtxSeqNum = rtxStreamSeqNums.merge(rtxSsrc, 1, Integer::sum)!!
 
-        rtpPacket.shiftPayloadRight(2)
-        rtpPacket.length = rtpPacket.length + 2
-        rtpPacket.originalSequenceNumber = rtpPacket.sequenceNumber
+        RtxPacket.addOriginalSequenceNumber(rtpPacket)
 
         rtpPacket.ssrc = rtxSsrc
         rtpPacket.payloadType = rtxPt