/**
* Retransmits a packet to {@link #channel}. If the destination supports the RTX format, the
* packet will be encapsulated in RTX, otherwise, the packet will be retransmitted as-is.
*
* @param pkt the packet to retransmit.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
public boolean retransmit(RawPacket pkt, TransformEngine after) {
boolean destinationSupportsRtx = channel.getRtxPayloadType() != -1;
boolean retransmitPlain;
if (destinationSupportsRtx) {
long rtxSsrc = getPairedSsrc(pkt.getSSRC());
if (rtxSsrc == -1) {
logger.warn("Cannot find SSRC for RTX, retransmitting plain.");
retransmitPlain = true;
} else {
retransmitPlain = !encapsulateInRtxAndTransmit(pkt, rtxSsrc);
}
} else {
retransmitPlain = true;
}
if (retransmitPlain) {
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
try {
mediaStream.injectPacket(pkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to retransmit a packet.");
return false;
}
}
}
return true;
}
/**
* Tries to find an SSRC paired with {@code ssrc} in an FID group in one of the channels from
* {@link #channel}'s {@code Content}. Returns -1 on failure.
*
* @param pkt the {@code RawPacket} that holds the RTP packet for which to find a paired SSRC.
* @return An SSRC paired with {@code ssrc} in an FID group, or -1.
*/
private long getRtxSsrc(RawPacket pkt) {
StreamRTPManager receiveRTPManager =
channel.getStream().getRTPTranslator().findStreamRTPManagerByReceiveSSRC(pkt.getSSRC());
MediaStreamTrackReceiver receiver = null;
if (receiveRTPManager != null) {
MediaStream receiveStream = receiveRTPManager.getMediaStream();
if (receiveStream != null) {
receiver = receiveStream.getMediaStreamTrackReceiver();
}
}
if (receiver == null) {
return -1;
}
RTPEncoding encoding = receiver.resolveRTPEncoding(pkt);
if (encoding == null) {
logger.warn(
"encoding_not_found"
+ ",stream_hash="
+ channel.getStream().hashCode()
+ " ssrc="
+ pkt.getSSRCAsLong());
return -1;
}
return encoding.getRTXSSRC();
}
/**
* Removes the RTX encapsulation from a packet.
*
* @param pkt the packet to remove the RTX encapsulation from.
* @return the original media packet represented by {@code pkt}, or null if we couldn't
* reconstruct the original packet.
*/
private RawPacket deRtx(RawPacket pkt) {
boolean success = false;
if (pkt.getPayloadLength() - pkt.getPaddingSize() < 2) {
// We need at least 2 bytes to read the OSN field.
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet with padding only: " + pkt);
}
return null;
}
long mediaSsrc = getPrimarySsrc(pkt);
if (mediaSsrc != -1) {
if (rtxAssociatedPayloadType != -1) {
int osn = pkt.getOriginalSequenceNumber();
// Remove the RTX header by moving the RTP header two bytes
// right.
byte[] buf = pkt.getBuffer();
int off = pkt.getOffset();
System.arraycopy(buf, off, buf, off + 2, pkt.getHeaderLength());
pkt.setOffset(off + 2);
pkt.setLength(pkt.getLength() - 2);
pkt.setSSRC((int) mediaSsrc);
pkt.setSequenceNumber(osn);
pkt.setPayloadType(rtxAssociatedPayloadType);
success = true;
} else {
logger.warn(
"RTX packet received, but no APT is defined. Packet "
+ "SSRC "
+ pkt.getSSRCAsLong()
+ ", associated media"
+ " SSRC "
+ mediaSsrc);
}
}
// If we failed to handle the RTX packet, drop it.
return success ? pkt : null;
}
/**
* Returns the SSRC paired with <tt>ssrc</tt> in an FID source-group, if any. If none is found,
* returns -1.
*
* @return the SSRC paired with <tt>ssrc</tt> in an FID source-group, if any. If none is found,
* returns -1.
*/
private long getPrimarySsrc(RawPacket pkt) {
MediaStreamTrackReceiver receiver = channel.getStream().getMediaStreamTrackReceiver();
if (receiver == null) {
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet from an unknown source.");
}
return -1;
}
RTPEncoding encoding = receiver.resolveRTPEncoding(pkt);
if (encoding == null) {
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet from an unknown source.");
}
return -1;
}
return encoding.getPrimarySSRC();
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = buf;
if (buf.length < len + 2) {
// FIXME The byte array newly allocated and assigned to newBuf must
// be made known to pkt eventually.
newBuf = new byte[len + 2];
}
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = len - headerLength;
System.arraycopy(buf, off, newBuf, 0, headerLength);
// FIXME If newBuf is actually buf, then we will override the first two
// bytes of the payload bellow.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
// FIXME We tried to extend the payload of pkt by two bytes above but
// we never told pkt that its length has increased by these two bytes.
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
pkt.setSSRC((int) rtxSsrc);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
pkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(pkt, /* data */ true, /* after */ null);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc, TransformEngine after) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = new byte[len + 2];
RawPacket rtxPkt = new RawPacket(newBuf, 0, len + 2);
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = pkt.getPayloadLength();
// Copy the header.
System.arraycopy(buf, off, newBuf, 0, headerLength);
// Set the OSN field.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
// Copy the payload.
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
rtxPkt.setSSRC((int) rtxSsrc);
rtxPkt.setPayloadType(rtxPayloadType);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
rtxPkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(rtxPkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
/**
* Sets the simulcast layers for this receiver and fires an event about it.
*
* @param simulcastLayers the simulcast layers for this receiver.
*/
public void setSimulcastLayers(SimulcastLayer[] simulcastLayers) {
this.simulcastLayers = simulcastLayers;
if (logger.isInfoEnabled()) {
if (simulcastLayers == null) {
logInfo("Simulcast disabled.");
} else {
for (SimulcastLayer l : simulcastLayers) {
logInfo(l.getOrder() + ": " + l.getPrimarySSRC());
}
}
}
executorService.execute(
new Runnable() {
public void run() {
firePropertyChange(SIMULCAST_LAYERS_PNAME, null, null);
}
});
// TODO If simulcastLayers has changed, then simulcastLayerFrameHistory
// has very likely become irrelevant. In other words, clear
// simulcastLayerFrameHistory.
}
/**
* Intercepts and handles outgoing RTX (RFC-4588) packets for an <tt>RtpChannel</tt>. Depending on
* whether the destination supports the RTX format (RFC-4588) either removes the RTX encapsulation
* (thus effectively retransmitting packets bit-by-bit) or updates the sequence number and SSRC
* fields taking into account the data sent to the particular <tt>RtpChannel</tt>.
*
* @author Boris Grozev
*/
public class RtxTransformer extends SinglePacketTransformerAdapter implements TransformEngine {
/**
* The <tt>Logger</tt> used by the <tt>RtxTransformer</tt> class and its instances to print debug
* information.
*/
private static final Logger logger = Logger.getLogger(RtxTransformer.class);
/** The <tt>RtpChannel</tt> for the transformer. */
private RtpChannel channel;
/** Maps an RTX SSRC to the last RTP sequence number sent with that SSRC. */
private final Map<Long, Integer> rtxSequenceNumbers = new HashMap<>();
/**
* Initializes a new <tt>RtxTransformer</tt> with a specific <tt>RtpChannel</tt>.
*
* @param channel the <tt>RtpChannel</tt> for the transformer.
*/
RtxTransformer(RtpChannel channel) {
this.channel = channel;
}
/** Implements {@link PacketTransformer#transform(RawPacket[])}. {@inheritDoc} */
@Override
public RawPacket transform(RawPacket pkt) {
byte rtxPt;
if (pkt != null
&& (rtxPt = channel.getRtxPayloadType()) != -1
&& pkt.getPayloadType() == rtxPt) {
pkt = handleRtxPacket(pkt);
}
return pkt;
}
/**
* Handles an RTX packet and returns it.
*
* @param pkt the packet to handle.
* @return the packet
*/
private RawPacket handleRtxPacket(RawPacket pkt) {
boolean destinationSupportsRtx = channel.getRtxPayloadType() != -1;
RawPacket mediaPacket = createMediaPacket(pkt);
if (mediaPacket != null) {
RawPacketCache cache = channel.getStream().getPacketCache();
if (cache != null) {
cache.cachePacket(mediaPacket);
}
}
if (destinationSupportsRtx) {
pkt.setSequenceNumber(
getNextRtxSequenceNumber(pkt.getSSRC() & 0xffffffffL, pkt.getSequenceNumber()));
} else {
// If the media packet was not reconstructed, drop the RTX packet
// (by returning null).
return mediaPacket;
}
return pkt;
}
/**
* Creates a {@code RawPacket} which represents the original packet encapsulated in {@code pkt}
* using the RTX format.
*
* @param pkt the packet from which to extract a media packet.
* @return the extracted media packet.
*/
private RawPacket createMediaPacket(RawPacket pkt) {
RawPacket mediaPacket = null;
long rtxSsrc = pkt.getSSRC() & 0xffffffffL;
// We need to know the SSRC paired with rtxSsrc *as seen by the
// receiver (i.e. this.channel)*. However, we only store SSRCs
// that endpoints *send* with.
// We therefore assume that SSRC re-writing has not introduced any
// new SSRCs and therefor the FID mappings known to the senders
// also apply to receivers.
RtpChannel sourceChannel = channel.getContent().findChannelByFidSsrc(rtxSsrc);
if (sourceChannel != null) {
long mediaSsrc = sourceChannel.getFidPairedSsrc(rtxSsrc);
if (mediaSsrc != -1) {
byte apt = sourceChannel.getRtxAssociatedPayloadType();
if (apt != -1) {
mediaPacket = new RawPacket(pkt.getBuffer().clone(), pkt.getOffset(), pkt.getLength());
// Remove the RTX header by moving the RTP header two bytes
// right.
byte[] buf = mediaPacket.getBuffer();
int off = mediaPacket.getOffset();
System.arraycopy(buf, off, buf, off + 2, mediaPacket.getHeaderLength());
mediaPacket.setOffset(off + 2);
mediaPacket.setLength(pkt.getLength() - 2);
mediaPacket.setSSRC((int) mediaSsrc);
mediaPacket.setSequenceNumber(pkt.getOriginalSequenceNumber());
mediaPacket.setPayloadType(apt);
}
}
}
return mediaPacket;
}
/** Implements {@link TransformEngine#getRTPTransformer()}. */
@Override
public PacketTransformer getRTPTransformer() {
return this;
}
/** Implements {@link TransformEngine#getRTCPTransformer()}. */
@Override
public PacketTransformer getRTCPTransformer() {
return null;
}
/**
* Returns the sequence number to use for a specific RTX packet, which is based on the packet's
* original sequence number.
*
* <p>Because we terminate the RTX format, and with simulcast we might translate RTX packets from
* multiple SSRCs into the same SSRC, we keep count of the RTX packets (and their sequence
* numbers) which we sent for each SSRC.
*
* @param ssrc the SSRC of the RTX stream for the packet.
* @param defaultSeq the default sequence number to use in case we don't (yet) have any
* information about <tt>ssrc</tt>.
* @return the sequence number which should be used for the next RTX packet sent using SSRC
* <tt>ssrc</tt>.
*/
private int getNextRtxSequenceNumber(long ssrc, int defaultSeq) {
Integer seq;
synchronized (rtxSequenceNumbers) {
seq = rtxSequenceNumbers.get(ssrc);
if (seq == null) seq = defaultSeq;
else seq++;
rtxSequenceNumbers.put(ssrc, seq);
}
return seq;
}
/**
* Returns the next RTP sequence number to use for the RTX stream for a particular SSRC.
*
* @param ssrc the SSRC.
* @return the next sequence number to use for SSRC <tt>ssrc</tt>.
*/
private int getNextRtxSequenceNumber(long ssrc) {
return getNextRtxSequenceNumber(ssrc, new Random().nextInt(1 << 16));
}
/**
* Tries to find an SSRC paired with {@code ssrc} in an FID group in one of the channels from
* {@link #channel}'s {@code Content}. Returns -1 on failure.
*
* @param ssrc the SSRC for which to find a paired SSRC.
* @return An SSRC paired with {@code ssrc} in an FID group, or -1.
*/
private long getPairedSsrc(long ssrc) {
RtpChannel sourceChannel = channel.getContent().findChannelByFidSsrc(ssrc);
if (sourceChannel != null) {
return sourceChannel.getFidPairedSsrc(ssrc);
}
return -1;
}
/**
* Retransmits a packet to {@link #channel}. If the destination supports the RTX format, the
* packet will be encapsulated in RTX, otherwise, the packet will be retransmitted as-is.
*
* @param pkt the packet to retransmit.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
public boolean retransmit(RawPacket pkt, TransformEngine after) {
boolean destinationSupportsRtx = channel.getRtxPayloadType() != -1;
boolean retransmitPlain;
if (destinationSupportsRtx) {
long rtxSsrc = getPairedSsrc(pkt.getSSRC());
if (rtxSsrc == -1) {
logger.warn("Cannot find SSRC for RTX, retransmitting plain.");
retransmitPlain = true;
} else {
retransmitPlain = !encapsulateInRtxAndTransmit(pkt, rtxSsrc);
}
} else {
retransmitPlain = true;
}
if (retransmitPlain) {
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
try {
mediaStream.injectPacket(pkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to retransmit a packet.");
return false;
}
}
}
return true;
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = buf;
if (buf.length < len + 2) {
// FIXME The byte array newly allocated and assigned to newBuf must
// be made known to pkt eventually.
newBuf = new byte[len + 2];
}
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = len - headerLength;
System.arraycopy(buf, off, newBuf, 0, headerLength);
// FIXME If newBuf is actually buf, then we will override the first two
// bytes of the payload bellow.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
// FIXME We tried to extend the payload of pkt by two bytes above but
// we never told pkt that its length has increased by these two bytes.
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
pkt.setSSRC((int) rtxSsrc);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
pkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(pkt, /* data */ true, /* after */ null);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
}
private void logInfo(String msg) {
if (logger.isInfoEnabled()) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.info(msg);
}
}
private void logError(String msg, Throwable e) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.error(msg, e);
}
private void logDebug(String msg) {
if (logger.isDebugEnabled()) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.debug(msg);
}
}
/**
* The <tt>SimulcastReceiver</tt> of a <tt>SimulcastEngine</tt> receives the simulcast streams from
* a simulcast enabled participant and manages 1 or more <tt>SimulcastLayer</tt>s. It fires a
* property change event whenever the simulcast layers that it manages change.
*
* <p>This class is thread safe.
*
* @author George Politis
* @author Lyubomir Marinov
*/
public class SimulcastReceiver extends PropertyChangeNotifier {
/**
* The <tt>Logger</tt> used by the <tt>ReceivingLayers</tt> class and its instances to print debug
* information.
*/
private static final Logger logger = Logger.getLogger(SimulcastReceiver.class);
/**
* The name of the property that gets fired when there's a change in the simulcast layers that
* this receiver manages.
*/
public static final String SIMULCAST_LAYERS_PNAME =
SimulcastReceiver.class.getName() + ".simulcastLayers";
/**
* The number of (video) frames which defines the interval of time (indirectly) during which a
* {@code SimulcastLayer} needs to receive data from its remote peer or it will be declared
* paused/stopped/not streaming by its {@code SimulcastReceiver}.
*/
static final int TIMEOUT_ON_FRAME_COUNT = 5;
/** The pool of threads utilized by this class. */
private static final ExecutorService executorService =
ExecutorUtils.newCachedThreadPool(true, SimulcastReceiver.class.getName());
/** Helper object that <tt>SwitchingSimulcastSender</tt> instances use to build JSON messages. */
private static final SimulcastMessagesMapper mapper = new SimulcastMessagesMapper();
/** The <tt>SimulcastEngine</tt> that owns this receiver. */
private final SimulcastEngine simulcastEngine;
/** The simulcast layers of this <tt>VideoChannel</tt>. */
private SimulcastLayer[] simulcastLayers;
/**
* Indicates whether we're receiving native or non-native simulcast from the associated endpoint.
* It determines whether the bridge should send messages over the data channels to manage the
* non-native simulcast. In the case of native simulcast, there's nothing to do for the bridge.
*
* <p>NOTE that at the time of this writing we only support native simulcast. Last time we tried
* non-native simulcast there was no way to limit the bitrate of lower layer streams and thus
* there was no point in implementing non-native simulcast.
*
* <p>NOTE^2 This has changed recently with the webrtc stack automatically limiting the stream
* bitrate based on its resolution (see commit 1c7d48d431e098ba42fa6bd9f1cfe69a703edee5 in the
* webrtc git repository). So it might be something that we will want to implement in the future
* for browsers that don't support native simulcast (Temasys).
*/
private boolean nativeSimulcast = true;
/**
* The history of the order/sequence of receipt of (video) frames by {@link #simulcastLayers}.
* Used in an attempt to speed up the detection of paused/stopped {@code SimulcastLayer}s by
* counting (video) frames.
*/
private final List<SimulcastLayer> simulcastLayerFrameHistory = new LinkedList<SimulcastLayer>();
/**
* Ctor.
*
* @param simulcastEngine the <tt>SimulcastEngine</tt> that owns this receiver.
*/
public SimulcastReceiver(SimulcastEngine simulcastEngine) {
this.simulcastEngine = simulcastEngine;
}
/**
* Gets the <tt>SimulcastEngine</tt> that owns this receiver.
*
* @return the <tt>SimulcastEngine</tt> that owns this receiver.
*/
public SimulcastEngine getSimulcastEngine() {
return this.simulcastEngine;
}
/**
* Returns true if the endpoint has signaled two or more simulcast layers.
*
* @return true if the endpoint has signaled two or more simulcast layers, false otherwise.
*/
public boolean hasLayers() {
SimulcastLayer[] sl = simulcastLayers;
return sl != null && sl.length != 0;
}
/**
* Returns a <tt>SimulcastLayer</tt> that is the closest match to the target order, or null if
* simulcast hasn't been configured for this receiver.
*
* @param targetOrder the simulcast layer target order.
* @return a <tt>SimulcastLayer</tt> that is the closest match to the target order, or null.
*/
public SimulcastLayer getSimulcastLayer(int targetOrder) {
SimulcastLayer[] layers = getSimulcastLayers();
if (layers == null || layers.length == 0) {
return null;
}
// Iterate through the simulcast layers that we own and return the one
// that matches best the targetOrder parameter.
SimulcastLayer next = layers[0];
for (int i = 1; i < Math.min(targetOrder + 1, layers.length); i++) {
if (!layers[i].isStreaming()) {
break;
}
next = layers[i];
}
return next;
}
/**
* Gets the simulcast layers of this simulcast manager in a new <tt>SortedSet</tt> so that the
* caller won't have to worry about the structure changing by some other thread.
*
* @return the simulcast layers of this receiver in a new sorted set if simulcast is signaled, or
* null.
*/
public SimulcastLayer[] getSimulcastLayers() {
return simulcastLayers;
}
/**
* Sets the simulcast layers for this receiver and fires an event about it.
*
* @param simulcastLayers the simulcast layers for this receiver.
*/
public void setSimulcastLayers(SimulcastLayer[] simulcastLayers) {
this.simulcastLayers = simulcastLayers;
if (logger.isInfoEnabled()) {
if (simulcastLayers == null) {
logInfo("Simulcast disabled.");
} else {
for (SimulcastLayer l : simulcastLayers) {
logInfo(l.getOrder() + ": " + l.getPrimarySSRC());
}
}
}
executorService.execute(
new Runnable() {
public void run() {
firePropertyChange(SIMULCAST_LAYERS_PNAME, null, null);
}
});
// TODO If simulcastLayers has changed, then simulcastLayerFrameHistory
// has very likely become irrelevant. In other words, clear
// simulcastLayerFrameHistory.
}
/**
* Notifies this instance that a <tt>DatagramPacket</tt> packet received on the data
* <tt>DatagramSocket</tt> of this <tt>Channel</tt> has been accepted for further processing
* within Jitsi Videobridge.
*
* @param pkt the accepted <tt>RawPacket</tt>.
*/
public void accepted(RawPacket pkt) {
// With native simulcast we don't have a notification when a stream
// has started/stopped. The simulcast manager implements a timeout
// for the high quality stream and it needs to be notified when
// the channel has accepted a datagram packet for the timeout to
// function correctly.
if (!hasLayers() || pkt == null) {
return;
}
// Find the layer that corresponds to this packet.
int acceptedSSRC = pkt.getSSRC();
SimulcastLayer[] layers = getSimulcastLayers();
SimulcastLayer acceptedLayer = null;
for (SimulcastLayer layer : layers) {
// We only care about the primary SSRC and not the RTX ssrc (or
// future FEC ssrc).
if ((int) layer.getPrimarySSRC() == acceptedSSRC) {
acceptedLayer = layer;
break;
}
}
// If this is not an RTP packet or if we can't find an accepted
// layer, log and return as it makes no sense to continue in this
// situation.
if (acceptedLayer == null) {
return;
}
// There are sequences of packets with increasing timestamps but without
// the marker bit set. Supposedly, they are probes to detect whether the
// bandwidth may increase. We think that they should cause neither the
// start nor the stop of any SimulcastLayer.
// XXX There's RawPacket#getPayloadLength() but the implementation
// includes pkt.paddingSize at the time of this writing and we do not
// know whether that's going to stay that way.
int pktPayloadLength = pkt.getLength() - pkt.getHeaderLength();
int pktPaddingSize = pkt.getPaddingSize();
if (pktPayloadLength <= pktPaddingSize) {
if (logger.isTraceEnabled()) {
logger.trace(
"pkt.payloadLength= "
+ pktPayloadLength
+ " <= pkt.paddingSize= "
+ pktPaddingSize
+ "("
+ pkt.getSequenceNumber()
+ ")");
}
return;
}
// NOTE(gp) we expect the base layer to be always on, so we never touch
// it or starve it.
// XXX Refer to the implementation of
// SimulcastLayer#touch(boolean, RawPacket) for an explanation of why we
// chose to use a return value.
boolean frameStarted = acceptedLayer.touch(pkt);
if (frameStarted) simulcastLayerFrameStarted(acceptedLayer, pkt, layers);
}
/**
* Maybe send a data channel command to the associated <tt>Endpoint</tt> to make it start
* streaming its hq stream, if it's being watched by some receiver.
*/
public void maybeSendStartHighQualityStreamCommand() {
if (nativeSimulcast || !hasLayers()) {
// In native simulcast the client adjusts its layers autonomously so
// we don't need (nor we can) to control it with data channel
// messages.
return;
}
Endpoint newEndpoint = getSimulcastEngine().getVideoChannel().getEndpoint();
SimulcastLayer[] newSimulcastLayers = getSimulcastLayers();
SctpConnection sctpConnection;
if (newSimulcastLayers == null
|| newSimulcastLayers.length <= 1
/* newEndpoint != null is implied */
|| (sctpConnection = newEndpoint.getSctpConnection()) == null
|| !sctpConnection.isReady()
|| sctpConnection.isExpired()) {
return;
}
// we have a new endpoint and it has an SCTP connection that is
// ready and not expired. if somebody else is watching the new
// endpoint, start its hq stream.
boolean startHighQualityStream = false;
for (Endpoint e :
getSimulcastEngine().getVideoChannel().getContent().getConference().getEndpoints()) {
// TODO(gp) need some synchronization here. What if the
// selected endpoint changes while we're in the loop?
if (e == newEndpoint) continue;
Endpoint eSelectedEndpoint = e.getEffectivelySelectedEndpoint();
if (newEndpoint == eSelectedEndpoint) {
// somebody is watching the new endpoint or somebody has not
// yet signaled its selected endpoint to the bridge, start
// the hq stream.
if (logger.isDebugEnabled()) {
Map<String, Object> map = new HashMap<String, Object>(3);
map.put("e", e);
map.put("newEndpoint", newEndpoint);
map.put("maybe", eSelectedEndpoint == null ? "(maybe) " : "");
StringCompiler sc =
new StringCompiler(map).c("{e.id} is {maybe} watching {newEndpoint.id}.");
logDebug(sc.toString().replaceAll("\\s+", " "));
}
startHighQualityStream = true;
break;
}
}
if (startHighQualityStream) {
// TODO(gp) this assumes only a single hq stream.
logDebug(
getSimulcastEngine().getVideoChannel().getEndpoint().getID()
+ " notifies "
+ newEndpoint.getID()
+ " to start its HQ stream.");
SimulcastLayer hqLayer = newSimulcastLayers[newSimulcastLayers.length - 1];
;
StartSimulcastLayerCommand command = new StartSimulcastLayerCommand(hqLayer);
String json = mapper.toJson(command);
try {
newEndpoint.sendMessageOnDataChannel(json);
} catch (IOException e) {
logError(newEndpoint.getID() + " failed to send message on data channel.", e);
}
}
}
/**
* Maybe send a data channel command to he associated simulcast sender to make it stop streaming
* its hq stream, if it's not being watched by any participant.
*/
public void maybeSendStopHighQualityStreamCommand() {
if (nativeSimulcast || !hasLayers()) {
// In native simulcast the client adjusts its layers autonomously so
// we don't need (nor we can) to control it with data channel
// messages.
return;
}
Endpoint oldEndpoint = getSimulcastEngine().getVideoChannel().getEndpoint();
SimulcastLayer[] oldSimulcastLayers = getSimulcastLayers();
SctpConnection sctpConnection;
if (oldSimulcastLayers != null
&& oldSimulcastLayers.length > 1
/* oldEndpoint != null is implied*/
&& (sctpConnection = oldEndpoint.getSctpConnection()) != null
&& sctpConnection.isReady()
&& !sctpConnection.isExpired()) {
// we have an old endpoint and it has an SCTP connection that is
// ready and not expired. if nobody else is watching the old
// endpoint, stop its hq stream.
boolean stopHighQualityStream = true;
for (Endpoint e :
getSimulcastEngine().getVideoChannel().getContent().getConference().getEndpoints()) {
// TODO(gp) need some synchronization here. What if the selected
// endpoint changes while we're in the loop?
if (oldEndpoint != e && (oldEndpoint == e.getEffectivelySelectedEndpoint())
|| e.getEffectivelySelectedEndpoint() == null) {
// somebody is watching the old endpoint or somebody has not
// yet signaled its selected endpoint to the bridge, don't
// stop the hq stream.
stopHighQualityStream = false;
break;
}
}
if (stopHighQualityStream) {
// TODO(gp) this assumes only a single hq stream.
logDebug(
getSimulcastEngine().getVideoChannel().getEndpoint().getID()
+ " notifies "
+ oldEndpoint.getID()
+ " to stop "
+ "its HQ stream.");
SimulcastLayer hqLayer = oldSimulcastLayers[oldSimulcastLayers.length - 1];
StopSimulcastLayerCommand command = new StopSimulcastLayerCommand(hqLayer);
String json = mapper.toJson(command);
try {
oldEndpoint.sendMessageOnDataChannel(json);
} catch (IOException e1) {
logError(oldEndpoint.getID() + " failed to send " + "message on data channel.", e1);
}
}
}
}
private void logDebug(String msg) {
if (logger.isDebugEnabled()) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.debug(msg);
}
}
private void logWarn(String msg) {
if (logger.isWarnEnabled()) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.warn(msg);
}
}
private void logError(String msg, Throwable e) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.error(msg, e);
}
private void logInfo(String msg) {
if (logger.isInfoEnabled()) {
msg = getSimulcastEngine().getVideoChannel().getEndpoint().getID() + ": " + msg;
logger.info(msg);
}
}
/**
* Notifies this {@code SimulcastReceiver} that a specific {@code SimulcastReceiver} has detected
* the start of a new video frame in the RTP stream that it represents. Determines whether any of
* {@link #simulcastLayers} other than {@code source} have been paused/stopped by the remote peer.
* The determination is based on counting (video) frames.
*
* @param source the {@code SimulcastLayer} which is the source of the event i.e. which has
* detected the start of a new video frame in the RTP stream that it represents
* @param pkt the {@code RawPacket} which was received by {@code source} and possibly influenced
* the decision that a new view frame was started in the RTP stream represented by {@code
* source}
* @param layers the set of {@code SimulcastLayer}s managed by this {@code SimulcastReceiver}.
* Explicitly provided to the method in order to avoid invocations of {@link
* #getSimulcastLayers()} because the latter makes a copy at the time of this writing.
*/
private void simulcastLayerFrameStarted(
SimulcastLayer source, RawPacket pkt, SimulcastLayer[] layers) {
// Allow the value of the constant TIMEOUT_ON_FRAME_COUNT to disable (at
// compile time) the frame-based approach to the detection of layer
// drops.
if (TIMEOUT_ON_FRAME_COUNT <= 1) return;
// Timeouts in layers caused by source may occur only based on the span
// (of time or received frames) during which source has received
// TIMEOUT_ON_FRAME_COUNT number of frames. The current method
// invocation signals the receipt of 1 frame by source.
int indexOfLastSourceOccurrenceInHistory = -1;
int sourceFrameCount = 0;
int ix = 0;
for (Iterator<SimulcastLayer> it = simulcastLayerFrameHistory.iterator(); it.hasNext(); ++ix) {
if (it.next() == source) {
if (indexOfLastSourceOccurrenceInHistory != -1) {
// Prune simulcastLayerFrameHistory so that it does not
// become unnecessarily long.
it.remove();
} else if (++sourceFrameCount >= TIMEOUT_ON_FRAME_COUNT - 1) {
// The span of TIMEOUT_ON_FRAME_COUNT number of frames
// received by source only is to be examined for the
// purposes of timeouts. The current method invocations
// signals the receipt of 1 frame by source so
// TIMEOUT_ON_FRAME_COUNT - 1 occurrences of source in
// simulcastLayerFrameHistory is enough.
indexOfLastSourceOccurrenceInHistory = ix;
}
}
}
if (indexOfLastSourceOccurrenceInHistory != -1) {
// Presumably, if a SimulcastLayer is active, all SimulcastLayers
// before it (according to SimulcastLayer's order) are active as
// well. Consequently, timeouts may occur in SimulcastLayers which
// are after source.
boolean maybeTimeout = false;
for (SimulcastLayer layer : layers) {
if (maybeTimeout) {
// There's no point in timing layer out if it's timed out
// already.
if (layer.isStreaming()) {
maybeTimeout(source, pkt, layer, indexOfLastSourceOccurrenceInHistory);
}
} else if (layer == source) {
maybeTimeout = true;
}
}
}
// As previously stated, the current method invocation signals the
// receipt of 1 frame by source.
simulcastLayerFrameHistory.add(0, source);
// TODO Prune simulcastLayerFrameHistory by forgetting so that it does
// not become too long.
}
/**
* Determines whether {@code effect} has been paused/stopped by the remote peer. The determination
* is based on counting frames and is triggered by the receipt of (a piece of) a new (video) frame
* by {@code cause}.
*
* @param cause the {@code SimulcastLayer} which has received (a piece of) a new (video) frame and
* has thus triggered a check on {@code effect}
* @param pkt the {@code RawPacket} which was received by {@code cause} and possibly influenced
* the decision to trigger a check on {@code effect}
* @param effect the {@code SimulcastLayer} which is to be checked whether it looks like it has
* been paused/stopped by the remote peer
* @param endIndexInSimulcastLayerFrameHistory
*/
private void maybeTimeout(
SimulcastLayer cause,
RawPacket pkt,
SimulcastLayer effect,
int endIndexInSimulcastLayerFrameHistory) {
Iterator<SimulcastLayer> it = simulcastLayerFrameHistory.iterator();
boolean timeout = true;
for (int ix = 0; it.hasNext() && ix < endIndexInSimulcastLayerFrameHistory; ++ix) {
if (it.next() == effect) {
timeout = false;
break;
}
}
if (timeout) {
effect.maybeTimeout(pkt);
if (!effect.isStreaming()) {
// Since effect has been determined to have been paused/stopped
// by the remote peer, its possible presence in
// simulcastLayerFrameHistory is irrelevant now. In other words,
// remove effect from simulcastLayerFrameHistory.
while (it.hasNext()) {
if (it.next() == effect) it.remove();
}
}
}
}
}
/**
* Maybe send a data channel command to the associated <tt>Endpoint</tt> to make it start
* streaming its hq stream, if it's being watched by some receiver.
*/
public void maybeSendStartHighQualityStreamCommand() {
if (nativeSimulcast || !hasLayers()) {
// In native simulcast the client adjusts its layers autonomously so
// we don't need (nor we can) to control it with data channel
// messages.
return;
}
Endpoint newEndpoint = getSimulcastEngine().getVideoChannel().getEndpoint();
SimulcastLayer[] newSimulcastLayers = getSimulcastLayers();
SctpConnection sctpConnection;
if (newSimulcastLayers == null
|| newSimulcastLayers.length <= 1
/* newEndpoint != null is implied */
|| (sctpConnection = newEndpoint.getSctpConnection()) == null
|| !sctpConnection.isReady()
|| sctpConnection.isExpired()) {
return;
}
// we have a new endpoint and it has an SCTP connection that is
// ready and not expired. if somebody else is watching the new
// endpoint, start its hq stream.
boolean startHighQualityStream = false;
for (Endpoint e :
getSimulcastEngine().getVideoChannel().getContent().getConference().getEndpoints()) {
// TODO(gp) need some synchronization here. What if the
// selected endpoint changes while we're in the loop?
if (e == newEndpoint) continue;
Endpoint eSelectedEndpoint = e.getEffectivelySelectedEndpoint();
if (newEndpoint == eSelectedEndpoint) {
// somebody is watching the new endpoint or somebody has not
// yet signaled its selected endpoint to the bridge, start
// the hq stream.
if (logger.isDebugEnabled()) {
Map<String, Object> map = new HashMap<String, Object>(3);
map.put("e", e);
map.put("newEndpoint", newEndpoint);
map.put("maybe", eSelectedEndpoint == null ? "(maybe) " : "");
StringCompiler sc =
new StringCompiler(map).c("{e.id} is {maybe} watching {newEndpoint.id}.");
logDebug(sc.toString().replaceAll("\\s+", " "));
}
startHighQualityStream = true;
break;
}
}
if (startHighQualityStream) {
// TODO(gp) this assumes only a single hq stream.
logDebug(
getSimulcastEngine().getVideoChannel().getEndpoint().getID()
+ " notifies "
+ newEndpoint.getID()
+ " to start its HQ stream.");
SimulcastLayer hqLayer = newSimulcastLayers[newSimulcastLayers.length - 1];
;
StartSimulcastLayerCommand command = new StartSimulcastLayerCommand(hqLayer);
String json = mapper.toJson(command);
try {
newEndpoint.sendMessageOnDataChannel(json);
} catch (IOException e) {
logError(newEndpoint.getID() + " failed to send message on data channel.", e);
}
}
}
/**
* Notifies this instance that a <tt>DatagramPacket</tt> packet received on the data
* <tt>DatagramSocket</tt> of this <tt>Channel</tt> has been accepted for further processing
* within Jitsi Videobridge.
*
* @param pkt the accepted <tt>RawPacket</tt>.
*/
public void accepted(RawPacket pkt) {
// With native simulcast we don't have a notification when a stream
// has started/stopped. The simulcast manager implements a timeout
// for the high quality stream and it needs to be notified when
// the channel has accepted a datagram packet for the timeout to
// function correctly.
if (!hasLayers() || pkt == null) {
return;
}
// Find the layer that corresponds to this packet.
int acceptedSSRC = pkt.getSSRC();
SimulcastLayer[] layers = getSimulcastLayers();
SimulcastLayer acceptedLayer = null;
for (SimulcastLayer layer : layers) {
// We only care about the primary SSRC and not the RTX ssrc (or
// future FEC ssrc).
if ((int) layer.getPrimarySSRC() == acceptedSSRC) {
acceptedLayer = layer;
break;
}
}
// If this is not an RTP packet or if we can't find an accepted
// layer, log and return as it makes no sense to continue in this
// situation.
if (acceptedLayer == null) {
return;
}
// There are sequences of packets with increasing timestamps but without
// the marker bit set. Supposedly, they are probes to detect whether the
// bandwidth may increase. We think that they should cause neither the
// start nor the stop of any SimulcastLayer.
// XXX There's RawPacket#getPayloadLength() but the implementation
// includes pkt.paddingSize at the time of this writing and we do not
// know whether that's going to stay that way.
int pktPayloadLength = pkt.getLength() - pkt.getHeaderLength();
int pktPaddingSize = pkt.getPaddingSize();
if (pktPayloadLength <= pktPaddingSize) {
if (logger.isTraceEnabled()) {
logger.trace(
"pkt.payloadLength= "
+ pktPayloadLength
+ " <= pkt.paddingSize= "
+ pktPaddingSize
+ "("
+ pkt.getSequenceNumber()
+ ")");
}
return;
}
// NOTE(gp) we expect the base layer to be always on, so we never touch
// it or starve it.
// XXX Refer to the implementation of
// SimulcastLayer#touch(boolean, RawPacket) for an explanation of why we
// chose to use a return value.
boolean frameStarted = acceptedLayer.touch(pkt);
if (frameStarted) simulcastLayerFrameStarted(acceptedLayer, pkt, layers);
}
/**
* Initializes a new <tt>RtxTransformer</tt> with a specific <tt>RtpChannel</tt>.
*
* @param channel the <tt>RtpChannel</tt> for the transformer.
*/
RtxTransformer(RtpChannel channel) {
super(RTPPacketPredicate.INSTANCE);
this.channel = channel;
this.logger = Logger.getLogger(classLogger, channel.getContent().getConference().getLogger());
}
/**
* Intercepts RTX (RFC-4588) packets coming from an {@link RtpChannel}, and removes their RTX
* encapsulation. Allows packets to be retransmitted to a channel (using the RTX format if the
* destination supports it).
*
* @author Boris Grozev
* @author George Politis
*/
public class RtxTransformer extends SinglePacketTransformerAdapter implements TransformEngine {
/**
* The {@link Logger} used by the {@link RtxTransformer} class to print debug information. Note
* that {@link Conference} instances should use {@link #logger} instead.
*/
private static final Logger classLogger = Logger.getLogger(RtxTransformer.class);
/** The <tt>RtpChannel</tt> for the transformer. */
private RtpChannel channel;
/** Maps an RTX SSRC to the last RTP sequence number sent with that SSRC. */
private final Map<Long, Integer> rtxSequenceNumbers = new HashMap<>();
/** The {@link Logger} to be used by this instance to print debug information. */
private final Logger logger;
/**
* The payload type number configured for RTX (RFC-4588), or -1 if none is configured (the other
* end does not support rtx).
*/
private byte rtxPayloadType = -1;
/** The "associated payload type" number for RTX. */
private byte rtxAssociatedPayloadType = -1;
/**
* Initializes a new <tt>RtxTransformer</tt> with a specific <tt>RtpChannel</tt>.
*
* @param channel the <tt>RtpChannel</tt> for the transformer.
*/
RtxTransformer(RtpChannel channel) {
super(RTPPacketPredicate.INSTANCE);
this.channel = channel;
this.logger = Logger.getLogger(classLogger, channel.getContent().getConference().getLogger());
}
/** Implements {@link PacketTransformer#transform(RawPacket[])}. {@inheritDoc} */
@Override
public RawPacket reverseTransform(RawPacket pkt) {
if (isRtx(pkt)) {
pkt = deRtx(pkt);
}
return pkt;
}
/**
* Determines whether {@code pkt} is an RTX packet.
*
* @param pkt the packet to check.
* @return {@code true} iff {@code pkt} is an RTX packet.
*/
private boolean isRtx(RawPacket pkt) {
byte rtxPt = rtxPayloadType;
return rtxPt != -1 && rtxPt == pkt.getPayloadType();
}
/**
* Removes the RTX encapsulation from a packet.
*
* @param pkt the packet to remove the RTX encapsulation from.
* @return the original media packet represented by {@code pkt}, or null if we couldn't
* reconstruct the original packet.
*/
private RawPacket deRtx(RawPacket pkt) {
boolean success = false;
if (pkt.getPayloadLength() - pkt.getPaddingSize() < 2) {
// We need at least 2 bytes to read the OSN field.
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet with padding only: " + pkt);
}
return null;
}
long mediaSsrc = getPrimarySsrc(pkt);
if (mediaSsrc != -1) {
if (rtxAssociatedPayloadType != -1) {
int osn = pkt.getOriginalSequenceNumber();
// Remove the RTX header by moving the RTP header two bytes
// right.
byte[] buf = pkt.getBuffer();
int off = pkt.getOffset();
System.arraycopy(buf, off, buf, off + 2, pkt.getHeaderLength());
pkt.setOffset(off + 2);
pkt.setLength(pkt.getLength() - 2);
pkt.setSSRC((int) mediaSsrc);
pkt.setSequenceNumber(osn);
pkt.setPayloadType(rtxAssociatedPayloadType);
success = true;
} else {
logger.warn(
"RTX packet received, but no APT is defined. Packet "
+ "SSRC "
+ pkt.getSSRCAsLong()
+ ", associated media"
+ " SSRC "
+ mediaSsrc);
}
}
// If we failed to handle the RTX packet, drop it.
return success ? pkt : null;
}
/** Implements {@link TransformEngine#getRTPTransformer()}. */
@Override
public PacketTransformer getRTPTransformer() {
return this;
}
/** Implements {@link TransformEngine#getRTCPTransformer()}. */
@Override
public PacketTransformer getRTCPTransformer() {
return null;
}
/**
* Returns the sequence number to use for a specific RTX packet, which is based on the packet's
* original sequence number.
*
* <p>Because we terminate the RTX format, and with simulcast we might translate RTX packets from
* multiple SSRCs into the same SSRC, we keep count of the RTX packets (and their sequence
* numbers) which we sent for each SSRC.
*
* @param ssrc the SSRC of the RTX stream for the packet.
* @return the sequence number which should be used for the next RTX packet sent using SSRC
* <tt>ssrc</tt>.
*/
private int getNextRtxSequenceNumber(long ssrc) {
Integer seq;
synchronized (rtxSequenceNumbers) {
seq = rtxSequenceNumbers.get(ssrc);
if (seq == null) seq = new Random().nextInt(0xffff);
else seq++;
rtxSequenceNumbers.put(ssrc, seq);
}
return seq;
}
/**
* Tries to find an SSRC paired with {@code ssrc} in an FID group in one of the channels from
* {@link #channel}'s {@code Content}. Returns -1 on failure.
*
* @param pkt the {@code RawPacket} that holds the RTP packet for which to find a paired SSRC.
* @return An SSRC paired with {@code ssrc} in an FID group, or -1.
*/
private long getRtxSsrc(RawPacket pkt) {
StreamRTPManager receiveRTPManager =
channel.getStream().getRTPTranslator().findStreamRTPManagerByReceiveSSRC(pkt.getSSRC());
MediaStreamTrackReceiver receiver = null;
if (receiveRTPManager != null) {
MediaStream receiveStream = receiveRTPManager.getMediaStream();
if (receiveStream != null) {
receiver = receiveStream.getMediaStreamTrackReceiver();
}
}
if (receiver == null) {
return -1;
}
RTPEncoding encoding = receiver.resolveRTPEncoding(pkt);
if (encoding == null) {
logger.warn(
"encoding_not_found"
+ ",stream_hash="
+ channel.getStream().hashCode()
+ " ssrc="
+ pkt.getSSRCAsLong());
return -1;
}
return encoding.getRTXSSRC();
}
/**
* Retransmits a packet to {@link #channel}. If the destination supports the RTX format, the
* packet will be encapsulated in RTX, otherwise, the packet will be retransmitted as-is.
*
* @param pkt the packet to retransmit.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
public boolean retransmit(RawPacket pkt, TransformEngine after) {
boolean destinationSupportsRtx = rtxPayloadType != -1;
boolean retransmitPlain;
if (destinationSupportsRtx) {
long rtxSsrc = getRtxSsrc(pkt);
if (rtxSsrc == -1) {
logger.warn(
"Cannot find SSRC for RTX, retransmitting plain. " + "SSRC=" + pkt.getSSRCAsLong());
retransmitPlain = true;
} else {
retransmitPlain = !encapsulateInRtxAndTransmit(pkt, rtxSsrc, after);
}
} else {
retransmitPlain = true;
}
if (retransmitPlain) {
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
try {
mediaStream.injectPacket(pkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to retransmit a packet.");
return false;
}
}
}
return true;
}
/**
* Notifies this instance that the dynamic payload types of the associated {@link MediaStream}
* have changed.
*/
public void onDynamicPayloadTypesChanged() {
rtxPayloadType = -1;
rtxAssociatedPayloadType = -1;
MediaStream mediaStream = channel.getStream();
Map<Byte, MediaFormat> mediaFormatMap = mediaStream.getDynamicRTPPayloadTypes();
Iterator<Map.Entry<Byte, MediaFormat>> it = mediaFormatMap.entrySet().iterator();
while (it.hasNext() && rtxPayloadType == -1) {
Map.Entry<Byte, MediaFormat> entry = it.next();
MediaFormat format = entry.getValue();
if (!Constants.RTX.equalsIgnoreCase(format.getEncoding())) {
continue;
}
// XXX(gp) we freak out if multiple codecs with RTX support are
// present.
rtxPayloadType = entry.getKey();
rtxAssociatedPayloadType = Byte.parseByte(format.getFormatParameters().get("apt"));
}
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc, TransformEngine after) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = new byte[len + 2];
RawPacket rtxPkt = new RawPacket(newBuf, 0, len + 2);
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = pkt.getPayloadLength();
// Copy the header.
System.arraycopy(buf, off, newBuf, 0, headerLength);
// Set the OSN field.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
// Copy the payload.
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
rtxPkt.setSSRC((int) rtxSsrc);
rtxPkt.setPayloadType(rtxPayloadType);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
rtxPkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(rtxPkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
/**
* Returns the SSRC paired with <tt>ssrc</tt> in an FID source-group, if any. If none is found,
* returns -1.
*
* @return the SSRC paired with <tt>ssrc</tt> in an FID source-group, if any. If none is found,
* returns -1.
*/
private long getPrimarySsrc(RawPacket pkt) {
MediaStreamTrackReceiver receiver = channel.getStream().getMediaStreamTrackReceiver();
if (receiver == null) {
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet from an unknown source.");
}
return -1;
}
RTPEncoding encoding = receiver.resolveRTPEncoding(pkt);
if (encoding == null) {
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet from an unknown source.");
}
return -1;
}
return encoding.getPrimarySSRC();
}
}