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/**
* Java RTP Library (jlibrtp)
* Copyright (C) 2006 Arne Kepp
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.jlibrtp;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A PktBuffer stores packets either for buffering purposes,
* or because they need to be assimilated to create a complete frame.
*
* This behavior can be controlled through rtpSession.pktBufBehavior()
*
* It optionally drops duplicate packets.
*
* Note that newest is the most recently received, i.e. highest timeStamp
* Next means new to old (from recently received to previously received)
*
* @author Arne Kepp
*/
public class PktBuffer {
/** Logger instance. */
private static final Logger LOGGER =
Logger.getLogger(PktBuffer.class.getName());
/** The RTPSession holds information common to all packetBuffers, such as max size */
RTPSession rtpSession;
/** SSRC of the the participant that this buffer is for */
long SSRC;
/** The parent participant */
Participant p;
/** The length of the buffer */
int length = 0;
/** The oldest, least recently received, packet */
PktBufNode oldest = null;
/** The newest, most recently received, packet */
PktBufNode newest = null;
/** The last sequence number received */
int lastSeqNumber = -1;
/** The last timestamp */
long lastTimestamp = -1;
/**
* Creates a new PktBuffer, a linked list of PktBufNode
*
* @param rtpSession the parent RTPSession
* @param p the participant to which this packetbuffer belongs.
* @param aPkt The first RTP packet, to be added to the buffer
*/
protected PktBuffer(RTPSession rtpSession, Participant p, RtpPkt aPkt) {
this.rtpSession = rtpSession;
this.p = p;
SSRC = aPkt.getSsrc();
PktBufNode newNode = new PktBufNode(aPkt);
oldest = newNode;
newest = newNode;
//lastSeqNumber = (aPkt.getSeqNumber() - 1);
//lastTimestamp = aPkt.getTimeStamp();
length = 1;
}
/**
* Adds a packet, this happens in constant time if they arrive in order.
* Optimized for the case where each pkt is a complete frame.
*
* @param aPkt the packet to be added to the buffer.
* @return integer, negative if operation failed (see code)
*/
protected synchronized int addPkt(RtpPkt aPkt) {
if(aPkt == null) {
LOGGER.info("! PktBuffer.addPkt(aPkt) aPkt was null");
return -5;
}
long timeStamp = aPkt.getTimeStamp();
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("-> PktBuffer.addPkt() , length:" + length + " , timeStamp of Pkt: " + Long.toString(timeStamp));
}
PktBufNode newNode = new PktBufNode(aPkt);
if(aPkt.getSsrc() != SSRC) {
LOGGER.warning("PktBuffer.addPkt() SSRCs don't match!");
}
int retVal = 0;
if(this.rtpSession.pktBufBehavior > 0) {
retVal = bufferedAddPkt(newNode);
} else if(this.rtpSession.pktBufBehavior == 0) {
retVal = filteredAddPkt(newNode);
} else if(this.rtpSession.pktBufBehavior == -1) {
retVal = unfilteredAddPkt(newNode);
}
if(LOGGER.isLoggable(Level.FINEST)) {
this.debugPrint();
LOGGER.finest("<- PktBuffer.addPkt() , length:" + length + " returning " + retVal);
}
return retVal;
}
/**
* Adds packets in the same order that they arrive,
* doesn't do any filering or processing.
*
* @param newNode the node to add to the packet buffer
* @return 0 if everything is okay, -1 otherwise
*/
private int unfilteredAddPkt(PktBufNode newNode) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("<-> PktBuffer.unfilteredAddPkt()");
}
//No magic, just add to the end
if(oldest != null) {
oldest.nextFrameQueueNode = newNode;
newNode.prevFrameQueueNode = oldest;
oldest = newNode;
} else {
oldest = newNode;
newest = newNode;
}
length++; // add this or no packet will be ever popped out!
return 0;
}
/**
* Takes care of duplicate packets
*
* @param newNode the node to add to the packet buffer
* @return 0 if everything is okay, -1 otherwise
*/
private int filteredAddPkt(PktBufNode newNode) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("<-> PktBuffer.filteredAddPkt()");
}
if(length == 0) {
// The buffer was empty, this packet is the one and only.
newest = newNode;
oldest = newNode;
length = 1;
} else {
// The packetbuffer is not empty.
if(newNode.timeStamp > newest.timeStamp || newNode.seqNum > newest.seqNum && (newNode.seqNum - newest.seqNum) < 10) {
// Packet came in order
newNode.nextFrameQueueNode = newest;
newest.prevFrameQueueNode = newNode;
newest = newNode;
length++;
} else {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("PktBuffer.filteredAddPkt Dropped a packet due to lag! " + newNode.timeStamp + " "
+ newNode.seqNum + " vs "+ oldest.timeStamp + " " + oldest.seqNum);
}
return -1;
}
}
return 0;
}
/**
* Does most of the packet organization for the application.
* Packets are put in order, duplicate packets or late arrivals are discarded
*
* If multiple packets make up a frame, these will also be organized
* by RTP timestamp and sequence number, and returned as a complete frame.
*
* @param newNode the node to add to the packet buffer
* @return 0 if everything is okay, -1 otherwise
*/
private int bufferedAddPkt(PktBufNode newNode) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("<-> PktBuffer.bufferedAddPkt()");
}
if(length == 0) {
// The buffer was empty, this packet is the one and only.
newest = newNode;
oldest = newNode;
} else {
// The packetbuffer is not empty.
if(newNode.timeStamp > newest.timeStamp || newNode.seqNum > newest.seqNum) {
// Packet came in order
newNode.nextFrameQueueNode = newest;
newest.prevFrameQueueNode = newNode;
newest = newNode;
} else {
//There are packets, we need to order this one right.
if(! pktOnTime(newNode.timeStamp, newNode.seqNum) && rtpSession.pktBufBehavior > -1) {
// We got this too late, can't put it in order anymore.
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("PktBuffer.addPkt Dropped a packet due to lag! " + newNode.timeStamp + " "
+ newNode.seqNum + " vs "+ oldest.timeStamp + " " + oldest.seqNum);
}
return -1;
}
//Need to do some real work, find out where it belongs (linear search from the back).
PktBufNode tmpNode = newest;
while(tmpNode.timeStamp > newNode.timeStamp) {
tmpNode = tmpNode.nextFrameQueueNode;
}
if( tmpNode.timeStamp == newNode.timeStamp
&& rtpSession.frameReconstruction
&& newNode.seqNum != tmpNode.seqNum) {
//Packet has same timestamp, presumably belongs to frame. Need to order within frame.
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("Found pkt with existing timeStamp: " + newNode.timeStamp);
}
int ret = addToFrame(tmpNode, newNode);
if(ret != 0) {
return ret;
}
} else {
// Check that it's not a duplicate
if(tmpNode.timeStamp == newNode.timeStamp && newNode.seqNum == tmpNode.seqNum) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("PktBuffer.addPkt Dropped a duplicate packet! "
+ newNode.timeStamp + " " + newNode.seqNum );
}
return -1;
}
// Insert into buffer
newNode.nextFrameQueueNode = tmpNode;
newNode.prevFrameQueueNode = tmpNode.prevFrameQueueNode;
// Update the node behind
if(newNode.prevFrameQueueNode != null) {
newNode.prevFrameQueueNode.nextFrameQueueNode = newNode;
}
tmpNode.prevFrameQueueNode = newNode;
if(newNode.timeStamp > newest.timeStamp) {
newest = newNode;
}
}
}
}
// Update the length of this buffer
length++;
return 0;
}
/**
*
* @param frameNode the node currently representing the frame in the packet buffer
* @param newNode the new node to be added to the frame
* @return 0 if no error, -2 if this is a duplicate packet
*/
private int addToFrame(PktBufNode frameNode, PktBufNode newNode) {
// Node has same timeStamp, assume pkt belongs to frame
if(frameNode.seqNum < newNode.seqNum) {
// this is not the first packet in the frame
frameNode.pktCount++;
// Find the right spot
while( frameNode.nextFrameNode != null
&& frameNode.nextFrameNode.seqNum < newNode.seqNum) {
frameNode = frameNode.nextFrameNode;
}
// Check whether packet is duplicate
if(frameNode.nextFrameNode != null
&& frameNode.nextFrameNode.seqNum == newNode.seqNum) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("PktBuffer.addPkt Dropped a duplicate packet!");
}
return -2;
}
newNode.nextFrameNode = frameNode.nextFrameNode;
frameNode.nextFrameNode = newNode;
} else {
// newNode has the lowest sequence number
newNode.nextFrameNode = frameNode;
newNode.pktCount = frameNode.pktCount + 1;
//Update the queue
if(frameNode.nextFrameQueueNode != null) {
frameNode.nextFrameQueueNode.prevFrameQueueNode = newNode;
newNode.nextFrameQueueNode = frameNode.nextFrameQueueNode;
frameNode.nextFrameQueueNode = null;
}
if(frameNode.prevFrameQueueNode != null) {
frameNode.prevFrameQueueNode.nextFrameQueueNode = newNode;
newNode.prevFrameQueueNode = frameNode.prevFrameQueueNode;
frameNode.prevFrameQueueNode = null;
}
if(newest.timeStamp == newNode.timeStamp) {
newest = newNode;
}
}
return 0;
}
/**
* Checks the oldest frame, if there is one, sees whether it is complete.
* @return Returns null if there are no complete frames available.
*/
protected synchronized DataFrame popOldestFrame() {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("-> PktBuffer.popOldestFrame()");
this.debugPrint();
}
if(this.rtpSession.pktBufBehavior > 0) {
return this.bufferedPopFrame();
} else {
return this.unbufferedPopFrame();
}
}
/**
* Will return the oldest frame without checking whether it is in
* the right order, or whether we should wate for late arrivals.
*
* @return the first frame on the queue, null otherwise
*/
private DataFrame unbufferedPopFrame() {
if(oldest != null) {
PktBufNode retNode = oldest;
popFrameQueueCleanup(retNode, retNode.seqNum);
return new DataFrame(retNode, this.p,
rtpSession.appIntf.frameSize(retNode.pkt.getPayloadType()));
} else {
return null;
}
}
/**
* Only returns if the buffer is full, i.e. length exceeds
* rtpSession.pktBufBehavior, or if the next packet directly
* follows the previous one returned to the application.
*
* @return first frame in order, null otherwise
*/
private DataFrame bufferedPopFrame() {
PktBufNode retNode = oldest;
/**
* Three scenarios:
* 1) There are no packets available
* 2) The first packet is vailable and in order
* 3) The first packet is not the next on in the sequence
* a) We have exceeded the wait buffer
* b) We wait
*/
// Pop it off, null all references.
if( retNode != null && (retNode.seqNum == this.lastSeqNumber + 1 || retNode.seqNum == 0
|| this.length > this.rtpSession.pktBufBehavior || this.lastSeqNumber < 0)) {
//if(tmpNode.pktCount == compLen) {
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("<- PktBuffer.popOldestFrame() returns frame");
}
DataFrame df;
if (rtpSession.isRegistered()) {
df = new DataFrame(retNode, this.p,
rtpSession.appIntf.frameSize(oldest.pkt.getPayloadType()));
} else {
df = new DataFrame(retNode, this.p, 1);
}
popFrameQueueCleanup(retNode, df.lastSeqNum);
return df;
} else {
// If we get here we have little to show for.
if(LOGGER.isLoggable(Level.FINEST)) {
LOGGER.finest("<- PktBuffer.popOldestFrame() returns null " + retNode.seqNum + " " + this.lastSeqNumber);
this.debugPrint();
}
return null;
}
}
/**
* Cleans the packet buffer before returning the frame,
* i.e. making sure the queue has a head etc.
*
* @param retNode the node that is about to be popped
* @param highestSeq the highest sequence number returned to the application
*/
private void popFrameQueueCleanup(PktBufNode retNode, int highestSeq) {
if(1 == length) {
//There's only one frame
newest = null;
oldest = null;
} else {
//There are more frames
oldest = oldest.prevFrameQueueNode;
oldest.nextFrameQueueNode = null;
}
// Update counters
length--;
//Find the highest sequence number associated with this timestamp
this.lastSeqNumber = highestSeq;
this.lastTimestamp = retNode.timeStamp;
}
/**
* Returns the length of the packetbuffer.
* @return number of frames (complete or not) in packetbuffer.
*/
protected int getLength() {
return length;
}
/**
* Checks whether a packet is not too late, i.e. the next packet has already been returned.
* @param timeStamp the RTP timestamp of the packet under consideration
* @param seqNum the sequence number of the packet under consideration
* @return true if newer packets have not been handed to the application
*/
protected boolean pktOnTime(long timeStamp, int seqNum) {
if(this.lastSeqNumber == -1) {
// First packet
return true;
} else {
if(seqNum >= this.lastSeqNumber) {
if(this.lastSeqNumber < 3 && timeStamp < this.lastTimestamp ) {
return false;
}
} else {
if(seqNum > 3 || timeStamp < this.lastTimestamp) {
return false;
}
}
}
return true;
}
/**
* Prints out the packet buffer, oldest node first (on top).
*/
protected void debugPrint() {
LOGGER.finest("PktBuffer.debugPrint() : length "+length+" SSRC "+SSRC+" lastSeqNum:"+lastSeqNumber);
PktBufNode tmpNode = oldest;
int i = 0;
while(tmpNode != null) {
//String str = tmpNode.timeStamp.toString();
LOGGER.finest(" " + i + " seqNum:"+tmpNode.seqNum+" timeStamp: " + tmpNode.timeStamp + " pktCount:" + tmpNode.pktCount );
i++;
tmpNode = tmpNode.prevFrameQueueNode;
}
}
}
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