/**
* Updates this <tt>RTPStatsMap</tt> with information it gets from the <tt>RawPacket</tt>.
*
* @param pkt the <tt>RawPacket</tt> that is being transmitted.
*/
public void apply(RawPacket pkt) {
int ssrc = pkt.getSSRC();
if (this.containsKey(ssrc)) {
RTPStatsEntry oldRtpStatsEntry = this.get(ssrc);
// Replace whatever was in there before. A feature of the two's
// complement encoding (which is used by Java integers) is that
// the bitwise results for add, subtract, and multiply are the
// same if both inputs are interpreted as signed values or both
// inputs are interpreted as unsigned values. (Other encodings
// like one's complement and signed magnitude don't have this
// properly.)
this.put(
ssrc,
new RTPStatsEntry(
ssrc,
oldRtpStatsEntry.getBytesSent()
+ pkt.getLength()
- pkt.getHeaderLength()
- pkt.getPaddingSize(),
oldRtpStatsEntry.getPacketsSent() + 1));
} else {
// Add a new <tt>RTPStatsEntry</tt> in this map.
this.put(
ssrc,
new RTPStatsEntry(
ssrc, pkt.getLength() - pkt.getHeaderLength() - pkt.getPaddingSize(), 1));
}
}
/**
* 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;
}
/**
* 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;
}
/**
* 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;
}
/**
* 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);
}
