18 files changed, 219 insertions, 42 deletions
diff --git a/Swiften/Network/BoostUDPSocket.cpp b/Swiften/Network/BoostUDPSocket.cpp
index 0f66b92..cd86990 100644
--- a/Swiften/Network/BoostUDPSocket.cpp
+++ b/Swiften/Network/BoostUDPSocket.cpp
@@ -137,7 +137,7 @@ void BoostUDPSocket::doRead()
 
 void BoostUDPSocket::handleSocketRead(const boost::system::error_code& error, size_t bytesTransferred)
 {
-	SWIFT_LOG(debug) << "Socket read " << error << std::endl;
+//	SWIFT_LOG(debug) << "Socket read " << error << std::endl;
 	if (!error) {
 		readBuffer_->resize(bytesTransferred);
 		eventLoop->postEvent(boost::bind(boost::ref(onDataRead), readBuffer_), shared_from_this());
@@ -161,7 +161,7 @@ void BoostUDPSocket::handleFirstRead(const boost::system::error_code &error, std
 
 void BoostUDPSocket::handleDataWritten(const boost::system::error_code& error)
 {
-	SWIFT_LOG(debug) << "Data written " << error << std::endl;
+//	SWIFT_LOG(debug) << "Data written " << error << std::endl;
 
 	//	if (!error) {
 	//		eventLoop->postEvent(boost::ref(onDataWritten), shared_from_this());
diff --git a/Swiften/ScreenSharing/IncomingScreenSharing.cpp b/Swiften/ScreenSharing/IncomingScreenSharing.cpp
index fbd4b16..43e3fbc 100644
--- a/Swiften/ScreenSharing/IncomingScreenSharing.cpp
+++ b/Swiften/ScreenSharing/IncomingScreenSharing.cpp
@@ -82,7 +82,8 @@ void IncomingScreenSharing::accept()
 		decoder = new VP8Decoder;
 		parser = new VP8RTPParser(decoder);
 		rtpSession->onIncomingPacket.connect(boost::bind(&VP8RTPParser::newPayloadReceived, parser, _1, _2, _3));
-		decoder->onNewImageDecoded.connect(boost::bind(&IncomingScreenSharing::handleNewImageDecoded, this, _1));
+		decoder->onNewFrameDecoded.connect(boost::bind(&IncomingScreenSharing::handleNewFrameDecoded, this, _1, _2));
+		decoder->onNewImageAvailable.connect(boost::bind(&IncomingScreenSharing::handleNewImageAvailable, this, _1));
 	}
 
 	onStateChange(ScreenSharing::Connecting);
@@ -115,7 +116,16 @@ JingleContentID IncomingScreenSharing::getContentID() const
 	return JingleContentID(initialContent->getName(), initialContent->getCreator());
 }
 
-void IncomingScreenSharing::handleNewImageDecoded(const Image& image)
+void IncomingScreenSharing::handleNewFrameDecoded(int pictureID, bool success)
+{
+	if (success) {
+		rtpSession->sendRPSIFeedback(pictureID);
+	} else {
+		rtpSession->sendSLIFeedback(pictureID);
+	}
+}
+
+void IncomingScreenSharing::handleNewImageAvailable(const Image& image)
 {
 	onStateChange(ScreenSharing::Receiving);
 	onNewImageReceived(image);
diff --git a/Swiften/ScreenSharing/IncomingScreenSharing.h b/Swiften/ScreenSharing/IncomingScreenSharing.h
index c46a6f8..d5dd817 100644
--- a/Swiften/ScreenSharing/IncomingScreenSharing.h
+++ b/Swiften/ScreenSharing/IncomingScreenSharing.h
@@ -44,7 +44,8 @@ namespace Swift {
 
 		private:
 			JingleContentID getContentID() const;
-			void handleNewImageDecoded(const Image& image);
+			void handleNewFrameDecoded(int pictureID, bool success);
+			void handleNewImageAvailable(const Image& image);
 			void handleEventSendingTimerTick();
 			void addLastMouseMoveIfDifferent();
 
diff --git a/Swiften/ScreenSharing/OutgoingScreenSharing.cpp b/Swiften/ScreenSharing/OutgoingScreenSharing.cpp
index 363b23c..6700a32 100644
--- a/Swiften/ScreenSharing/OutgoingScreenSharing.cpp
+++ b/Swiften/ScreenSharing/OutgoingScreenSharing.cpp
@@ -136,6 +136,7 @@ void OutgoingScreenSharing::startRTPSession()
 		packetizer = new VP8RTPPacketizer;
 		encoder = new VP8Encoder(packetizer, width, height);
 		packetizer->onNewPayloadReady.connect(boost::bind(&OutgoingScreenSharing::handleNewPayloadReady, this, _1, _2));
+		rtpSession->onRPSIFeedback.connect(boost::bind(&VP8Encoder::handleRPSIFeedback, static_cast<VP8Encoder*>(encoder), _1));
 		onReady();
 		onStateChange(ScreenSharing::BroadCasting);
 	}
diff --git a/Swiften/ScreenSharing/RTPSession.h b/Swiften/ScreenSharing/RTPSession.h
index e4aa9c1..c9c6ae8 100644
--- a/Swiften/ScreenSharing/RTPSession.h
+++ b/Swiften/ScreenSharing/RTPSession.h
@@ -29,9 +29,14 @@ namespace Swift {
 			virtual void injectData(const SafeByteArray& data) = 0;
 			virtual void stop(int maxWaitMs = 100) = 0;
 
+			virtual void sendSLIFeedback(int pictureID) = 0;
+			virtual void sendRPSIFeedback(int pictureID) = 0;
+
 			virtual size_t getMaxRTPPayloadSize() const = 0;
 
 		public:
 			boost::signal<void (uint8_t* data, size_t len, bool marker)> onIncomingPacket;
+			boost::signal<void (int sixLeastBitsPictureID)> onSLIFeedback;
+			boost::signal<void (int pictureID)> onRPSIFeedback;
 	};
 }
diff --git a/Swiften/ScreenSharing/RTPSessionImpl.cpp b/Swiften/ScreenSharing/RTPSessionImpl.cpp
index 922ffa2..33b9c2e 100644
--- a/Swiften/ScreenSharing/RTPSessionImpl.cpp
+++ b/Swiften/ScreenSharing/RTPSessionImpl.cpp
@@ -10,6 +10,7 @@
 #include <Swiften/Network/BoostUDPSocket.h>
 #include <Swiften/Base/boost_bsignals.h>
 #include <Swiften/Network/UDPSocket.h>
+#include <Swiften/Base/Log.h>
 
 #include <boost/algorithm/string/split.hpp>
 #include <boost/algorithm/string/classification.hpp>
@@ -63,9 +64,9 @@ RTPSessionImpl::RTPSessionImpl(boost::shared_ptr<UDPSocket> udpSocket, const RTP
 	// IMPORTANT: The local timestamp unit MUST be set, otherwise RTCP Sender Report info will be calculated wrong
 	sessparams.SetOwnTimestampUnit(1.0 / payloadType.getClockrate());
 
-	checkError(session.Create(sessparams, &transparams, jrtplib::RTPTransmitter::ExternalProto));
+	checkError(Create(sessparams, &transparams, jrtplib::RTPTransmitter::ExternalProto));
 
-	packetInjecter = static_cast<jrtplib::RTPExternalTransmissionInfo*>(session.GetTransmissionInfo())->GetPacketInjector();
+	packetInjecter = static_cast<jrtplib::RTPExternalTransmissionInfo*>(GetTransmissionInfo())->GetPacketInjector();
 
 	udpSocket->onDataRead.connect(boost::bind(&RTPSessionImpl::handleDataRead, this, _1));
 	udpSocket->listen();
@@ -78,27 +79,27 @@ RTPSessionImpl::~RTPSessionImpl()
 
 void RTPSessionImpl::poll()
 {
-	checkError(session.Poll()); // Required if threading disabled
+	checkError(Poll()); // Required if threading disabled
 }
 
 void RTPSessionImpl::checkIncomingPackets()
 {
 	// session.BeginDataAccess(); // useless without threading
-	if (session.GotoFirstSourceWithData() && session.GetCurrentSourceInfo()->GetRTPDataAddress()->IsSameAddress(jRTPRemotePeer)) {
+	if (GotoFirstSourceWithData() && GetCurrentSourceInfo()->GetRTPDataAddress()->IsSameAddress(jRTPRemotePeer)) {
 		do {
 			jrtplib::RTPPacket *pack;
-			while ((pack = session.GetNextPacket()) != NULL) {
+			while ((pack = GetNextPacket()) != NULL) {
 				onIncomingPacket(pack->GetPayloadData(), pack->GetPayloadLength(), pack->HasMarker());
-				session.DeletePacket(pack);
+				DeletePacket(pack);
 			}
-		} while (session.GotoNextSourceWithData());
+		} while (GotoNextSourceWithData());
 	}
 	// session.EndDataAccess(); // useless without threading
 }
 
 void RTPSessionImpl::sendPacket(const SafeByteArray& data, int timestampinc, bool marker)
 {
-	checkError(session.SendPacket((void*)(data.data()), data.size(), payloadType.getID(), marker, timestampinc));
+	checkError(SendPacket((void*)(data.data()), data.size(), payloadType.getID(), marker, timestampinc));
 	poll();
 }
 
@@ -111,16 +112,69 @@ void RTPSessionImpl::injectData(const SafeByteArray& data)
 
 void RTPSessionImpl::stop(int maxWaitMs)
 {
-	session.BYEDestroy(jrtplib::RTPTime(0, maxWaitMs * 1000), "", 0);
+	BYEDestroy(jrtplib::RTPTime(0, maxWaitMs * 1000), "", 0);
 	udpSocket->close();
 }
 
+void RTPSessionImpl::sendSLIFeedback(int pictureID)
+{
+	// Send an SLI as negative feedback. VP8: 0, total number of macroblocks, pictureID (6 bits)
+	int first = 0; // 13 bits
+	int number = 0; // 13 bits // TODO : Find the total	number of macroblocks per frame
+
+	uint32_t data = 0;
+	data |= first << 19;
+	data |= (number & 2047) << 6;
+	data |= (pictureID & 63);
+
+	SendUnknownPacket(false, PSFB, PSFB_SLI, (void*)&data, sizeof(uint32_t));
+}
+
+void RTPSessionImpl::sendRPSIFeedback(int pictureID)
+{
+	// Send an RPSI as positive feedback. With VP8, it only contains the picture ID (7 bits)
+	int pb = 9; // trailing padding bits
+	int pt = payloadType.getID(); // payload type (7 bits)
+
+	uint32_t data = 0;
+	data |= pb << 24;
+	data |= (pt & 127) << 16;
+	data |= (pictureID & 127) << 9;
+
+	SendUnknownPacket(false, PSFB, PSFB_RPSI, (void*)&data, sizeof(uint32_t));
+}
+
 size_t RTPSessionImpl::getMaxRTPPayloadSize() const
 {
 	jrtplib::RTPSessionParams sessparams;
 	return sessparams.GetMaximumPacketSize();
 }
 
+void RTPSessionImpl::OnUnknownPacketType(jrtplib::RTCPPacket* rtcpPack, const jrtplib::RTPTime& /*receivetime*/, const jrtplib::RTPAddress* senderAddress)
+{
+	if (!senderAddress->IsSameAddress(jRTPRemotePeer))
+		return;
+
+	uint8_t* data = rtcpPack->GetPacketData();
+	size_t len = rtcpPack->GetPacketLength();
+	jrtplib::RTCPCommonHeader* rtcpHdr = (jrtplib::RTCPCommonHeader*)data;
+	int type = rtcpHdr->packettype;
+	if (type != PSFB)
+		return;
+
+	int subtype = rtcpHdr->count;
+	switch (subtype) {
+		case PSFB_SLI:
+			parseSLIFeedBack(data + 8, len - 8);
+			break;
+		case PSFB_RPSI:
+			parseRPSIFeedBack(data + 8, len - 8);
+			break;
+		default:
+			break;
+	}
+}
+
 void RTPSessionImpl::checkError(int rtperr) const
 {
 	if (rtperr < 0)
@@ -132,6 +186,30 @@ void RTPSessionImpl::handleDataRead(boost::shared_ptr<SafeByteArray> data)
 	injectData(*data);
 }
 
+void RTPSessionImpl::parseSLIFeedBack(uint8_t* data, size_t len)
+{
+	SWIFT_LOG(debug) << "Got SLI feedback (negative)" << std::endl;
+
+	if (len < 4)
+		return;
+	int pictureID = data[len - 1] & 63; // pictureID correspond to the 6 last bits
+	onSLIFeedback(pictureID);
+}
+
+void RTPSessionImpl::parseRPSIFeedBack(uint8_t* data, size_t len)
+{
+	SWIFT_LOG(debug) << "Got RPSI feedback (postive)" << std::endl;
+
+	if (len < 4)
+		return;
+	int pb = data[0]; // First byte : trailing padding bits
+	uint32_t intData = *((uint32_t*)(data));
+	intData >>= pb; // remove padding bits
+	int pictureID = (intData & 127); // pictureID correspond to the 7 last bits
+	onRPSIFeedback(pictureID);
+
+}
+
 jrtplib::RTPAddress* RTPSessionImpl::nativeAddressToJRTPAddress(const HostAddressPort& hostAddressPort)
 {
 	jrtplib::RTPAddress* jrtpAddress = 0;
diff --git a/Swiften/ScreenSharing/RTPSessionImpl.h b/Swiften/ScreenSharing/RTPSessionImpl.h
index 47af60b..2736605 100644
--- a/Swiften/ScreenSharing/RTPSessionImpl.h
+++ b/Swiften/ScreenSharing/RTPSessionImpl.h
@@ -34,10 +34,7 @@ namespace Swift {
 			jrtplib::RTPAddress* jRTPLocalAddress;
 	};
 
-	class RTPSessionImpl : public RTPSession {
-		public:
-			typedef boost::shared_ptr<RTPSession> ref;
-
+	class RTPSessionImpl : public RTPSession, jrtplib::RTPSession {
 		public:
 			RTPSessionImpl(boost::shared_ptr<UDPSocket> udpSocket, const RTPPayloadType& payloadType);
 			virtual ~RTPSessionImpl();
@@ -48,21 +45,38 @@ namespace Swift {
 			virtual void injectData(const SafeByteArray &data);
 			virtual void stop(int maxWaitMs = 100);
 
+			virtual void sendSLIFeedback(int pictureID);
+			virtual void sendRPSIFeedback(int pictureID);
+
 			virtual size_t getMaxRTPPayloadSize() const;
 
 		public:
 			static jrtplib::RTPAddress* nativeAddressToJRTPAddress(const HostAddressPort& hostAddressPort);
 
+		protected:
+			void OnUnknownPacketType(jrtplib::RTCPPacket* rtcpPack, const jrtplib::RTPTime& /*receivetime*/, const jrtplib::RTPAddress* senderAddress);
+
+		private:
+			enum PacketType {
+				PSFB = 206,
+			};
+
+			enum SubPacketType {
+				PSFB_SLI = 2,
+				PSFB_RPSI = 3,
+			};
+
 		private:
 			void checkError(int rtperr) const;
 			void handleDataRead(boost::shared_ptr<SafeByteArray> data);
+			void parseSLIFeedBack(uint8_t* data, size_t len);
+			void parseRPSIFeedBack(uint8_t* data, size_t len);
 
 		private:
 			boost::shared_ptr<UDPSocket> udpSocket;
 			RTPPayloadType payloadType;
 			jrtplib::RTPAddress* jRTPRemotePeer;
 			Sender sender;
-			jrtplib::RTPSession session;
 			jrtplib::RTPExternalPacketInjecter *packetInjecter;
 	};
 }
diff --git a/Swiften/ScreenSharing/ScreenSharing.cpp b/Swiften/ScreenSharing/ScreenSharing.cpp
index f1b7ebf..7fb1280 100644
--- a/Swiften/ScreenSharing/ScreenSharing.cpp
+++ b/Swiften/ScreenSharing/ScreenSharing.cpp
@@ -65,11 +65,27 @@ bool ScreenSharing::addBestCandidate(boost::shared_ptr<JingleRawUDPTransportPayl
 		}
 	}*/
 
+	SWIFT_LOG(debug) << "Screen sharing: Addresses available: " << std::endl;
+	foreach (const NetworkInterface& interface, interfaces) {
+		SWIFT_LOG(debug) << "\tInterface: " << interface.getName() << std::endl;
+		foreach (const HostAddress& addr, interface.getAddresses()) {
+			SWIFT_LOG(debug) << "\t\t" << addr.getRawAddress().to_string() << std::endl;
+		}
+	}
+
+	std::string scopeLinkBeginning("fe80");
 	foreach (const NetworkInterface& interface, interfaces) {
 		if (!interface.isLoopback()) { // exclude loopback
 			foreach (const HostAddress& addr, interface.getAddresses()) {
-//				int port = serverSocket->bindOnAvailablePort(addr);
-				int port = serverSocket->bind(HostAddressPort(addr, 29999));
+				// Disable ipv6 for now
+				if (addr.getRawAddress().is_v6())
+					continue;
+				// Ignore link scope ipv6 addr
+				if (addr.getRawAddress().is_v6() && addr.toString().compare(2, scopeLinkBeginning.length(), scopeLinkBeginning) == 0)
+					continue;
+
+				int port = serverSocket->bindOnAvailablePort(addr);
+//				int port = serverSocket->bind(HostAddressPort(addr, 29999));
 				if (!port)
 					continue;
 
@@ -82,6 +98,18 @@ bool ScreenSharing::addBestCandidate(boost::shared_ptr<JingleRawUDPTransportPayl
 		}
 	}
 
+	/*
+	int port = serverSocket->bind(HostAddressPort(HostAddress("0.0.0.0"), 29999));
+	if (!port)
+		return false;
+
+	candidate.hostAddressPort = HostAddressPort(HostAddress("82.225.14.174"), 29999);
+	candidate.type = JingleRawUDPTransportPayload::Candidate::Host;
+	transport->addCandidate(candidate);
+
+	return true;
+*/
+
 	// else loopback for self sharing
 	/*if (!interfaces.empty() && !interfaces.front().getAddresses().empty()) {
 		int port = serverSocket->bindOnAvailablePort(interfaces.front().getAddresses().front());
diff --git a/Swiften/ScreenSharing/VP8Decoder.cpp b/Swiften/ScreenSharing/VP8Decoder.cpp
index 40f631f..2634cc5 100644
--- a/Swiften/ScreenSharing/VP8Decoder.cpp
+++ b/Swiften/ScreenSharing/VP8Decoder.cpp
@@ -40,21 +40,23 @@ void VP8Decoder::updateCodecConfig()
 	}
 }
 
-void VP8Decoder::decodeFrame(const std::vector<uint8_t>& frame)
+void VP8Decoder::decodeFrame(const std::vector<uint8_t>& frame, int pictureID)
 {
 	// Decode the frame
 	vpx_codec_err_t err = vpx_codec_decode(&codecContext, &frame[0], frame.size(), NULL, 0);
 	if (err) {
 		SWIFT_LOG(debug) << "VP8 Decoder: Failed to decode frame, " << vpx_codec_err_to_string(err) << std::endl;
-		// TODO: exception ?
+		onNewFrameDecoded(pictureID, false);
 		return;
+	} else {
+		onNewFrameDecoded(pictureID, true);
 	}
 
 	vpx_codec_iter_t iter = NULL;
 	vpx_image_t* img;
 	while ((img = vpx_codec_get_frame(&codecContext, &iter))) {
 		Image rgbImg = convertYV12toRGB(img);
-		onNewImageDecoded(rgbImg);
+		onNewImageAvailable(rgbImg);
 	}
 }
 
diff --git a/Swiften/ScreenSharing/VP8Decoder.h b/Swiften/ScreenSharing/VP8Decoder.h
index 8b2575a..0bdc664 100644
--- a/Swiften/ScreenSharing/VP8Decoder.h
+++ b/Swiften/ScreenSharing/VP8Decoder.h
@@ -21,7 +21,7 @@ namespace Swift {
 
 			void updateCodecConfig();
 
-			virtual void decodeFrame(const std::vector<uint8_t>& frame);
+			virtual void decodeFrame(const std::vector<uint8_t> &frame, int pictureID);
 
 		private:
 			Image convertYV12toRGB(const vpx_image_t* img);
diff --git a/Swiften/ScreenSharing/VP8Encoder.cpp b/Swiften/ScreenSharing/VP8Encoder.cpp
index 7a88418..c25e153 100644
--- a/Swiften/ScreenSharing/VP8Encoder.cpp
+++ b/Swiften/ScreenSharing/VP8Encoder.cpp
@@ -14,7 +14,7 @@ namespace Swift {
 
 VP8Encoder::VP8Encoder(VP8RTPPacketizer* packetizer, unsigned int  width, unsigned int  height)
 	: VideoEncoder(),
-	  packetizer(packetizer), codecInterface(vpx_codec_vp8_cx()), imageBuffer(0), codecFlags(0), frameFlags(0), frameNumber(0)
+	  packetizer(packetizer), codecInterface(vpx_codec_vp8_cx()), imageBuffer(0), codecFlags(0), frameFlags(0), frameNumber(0), pictureID(0), rpsiReceived(true)
 {
 	SWIFT_LOG(debug) << "VP8 Encoder:" << vpx_codec_iface_name(codecInterface) << std::endl;
 
@@ -60,6 +60,10 @@ void VP8Encoder::updateCodecConfig()
 		SWIFT_LOG(error) << "VP8 Encoder: Failed to allocate image" << std::endl;
 		// TODO: exception
 	}
+
+	frameNumber = 0;
+	pictureID = rand() % 128;
+	rpsiReceived = true;
 }
 
 void VP8Encoder::encodeImage(const Image& frame)
@@ -70,7 +74,12 @@ void VP8Encoder::encodeImage(const Image& frame)
 		return;
 	}
 
-	vpx_codec_err_t err = vpx_codec_encode(&codecContext, imageBuffer, frameNumber, 1, frameFlags, VPX_DL_REALTIME);
+	vpx_enc_frame_flags_t localFrameFlags = frameFlags;
+	if (!rpsiReceived && frameNumber > 1) {
+		localFrameFlags |= VP8_EFLAG_NO_REF_LAST; // VP8_EFLAG_FORCE_GF; // TODO: VP8_EFLAG_NO_REF_LAST;
+	}
+
+	vpx_codec_err_t err = vpx_codec_encode(&codecContext, imageBuffer, frameNumber, 1, localFrameFlags, VPX_DL_REALTIME);
 	if (err) {
 		SWIFT_LOG(error) << "VP8 Encoder: Failed to encode frame, " << vpx_codec_err_to_string(err) << std::endl;
 		// TODO: exception ?
@@ -82,7 +91,7 @@ void VP8Encoder::encodeImage(const Image& frame)
 	while ((pkt = vpx_codec_get_cx_data(&codecContext, &iter))) {
 		switch (pkt->kind) {
 			case VPX_CODEC_CX_FRAME_PKT:
-				packetizer->packetizeFrame(pkt);
+				packetizer->packetizeFrame(pkt, pictureID);
 				break;
 			default:
 				break;
@@ -90,6 +99,13 @@ void VP8Encoder::encodeImage(const Image& frame)
 	}
 
 	++frameNumber;
+	pictureID = (pictureID + 1) % 128;
+	rpsiReceived = false;
+}
+
+void VP8Encoder::handleRPSIFeedback(int /*pictureID*/)
+{
+	rpsiReceived = true;
 }
 
 bool VP8Encoder::convertRGB24toYV12inBuffer(const Image& frame)
diff --git a/Swiften/ScreenSharing/VP8Encoder.h b/Swiften/ScreenSharing/VP8Encoder.h
index 0a343bb..62a6ea8 100644
--- a/Swiften/ScreenSharing/VP8Encoder.h
+++ b/Swiften/ScreenSharing/VP8Encoder.h
@@ -25,6 +25,8 @@ namespace Swift {
 
 			virtual void encodeImage(const Image& frame);
 
+			virtual void handleRPSIFeedback(int /*pictureID*/);
+
 		private:
 			bool convertRGB24toYV12inBuffer(const Image& frame);
 
@@ -37,6 +39,8 @@ namespace Swift {
 			vpx_codec_flags_t codecFlags;
 			vpx_enc_frame_flags_t frameFlags;
 			int frameNumber;
+			int pictureID;
+			bool rpsiReceived;
 	};
 
 }
diff --git a/Swiften/ScreenSharing/VP8RTPPacketizer.cpp b/Swiften/ScreenSharing/VP8RTPPacketizer.cpp
index b88e2171..454f35f 100644
--- a/Swiften/ScreenSharing/VP8RTPPacketizer.cpp
+++ b/Swiften/ScreenSharing/VP8RTPPacketizer.cpp
@@ -12,7 +12,7 @@ VP8RTPPacketizer::VP8RTPPacketizer()
 {
 }
 
-void VP8RTPPacketizer::packetizeFrame(const vpx_codec_cx_pkt_t* pkt)
+void VP8RTPPacketizer::packetizeFrame(const vpx_codec_cx_pkt_t* pkt, int pictureID)
 {
 	if (pkt->kind != VPX_CODEC_CX_FRAME_PKT)
 		return;
@@ -30,10 +30,14 @@ void VP8RTPPacketizer::packetizeFrame(const vpx_codec_cx_pkt_t* pkt)
 		payloadBuffer.clear();
 
 		// Payload descriptor
-		uint8_t req = 0;
+		uint8_t req = XBit;
 		if (firstPacket)
 			req |= SBit;
+		uint8_t optX = IBit;
+		uint8_t optI = (pictureID & 127); // pictureID
 		payloadBuffer.push_back(req);
+		payloadBuffer.push_back(optX);
+		payloadBuffer.push_back(optI);
 
 		// Payload header
 		if (firstPacket) {
diff --git a/Swiften/ScreenSharing/VP8RTPPacketizer.h b/Swiften/ScreenSharing/VP8RTPPacketizer.h
index c56e754..f7858da 100644
--- a/Swiften/ScreenSharing/VP8RTPPacketizer.h
+++ b/Swiften/ScreenSharing/VP8RTPPacketizer.h
@@ -20,12 +20,14 @@ namespace Swift {
 		public:
 			VP8RTPPacketizer();
 
-			void packetizeFrame(const vpx_codec_cx_pkt_t* pkt);
+			void packetizeFrame(const vpx_codec_cx_pkt_t* pkt, int pictureID);
 
 			boost::signal<void (const std::vector<uint8_t>&, bool marker)> onNewPayloadReady;
 
 		private:
 			static const uint8_t SBit = 1 << 4;
+			static const uint8_t XBit = 1 << 7;
+			static const uint8_t IBit = 1 << 7;
 			static const uint8_t HBit = 1 << 4;
 			static const uint8_t Size0BitMask = 7;
 			static const uint8_t Size0BitShift = 5;
diff --git a/Swiften/ScreenSharing/VP8RTPParser.cpp b/Swiften/ScreenSharing/VP8RTPParser.cpp
index 053a50a..d44140b 100644
--- a/Swiften/ScreenSharing/VP8RTPParser.cpp
+++ b/Swiften/ScreenSharing/VP8RTPParser.cpp
@@ -11,37 +11,43 @@
 namespace Swift {
 
 VP8RTPParser::VP8RTPParser(VideoDecoder* decoder)
-	: decoder(decoder), firstPacket(true)
+	: decoder(decoder), firstPacket(true), pictureID(0)
 {
 }
 
 void VP8RTPParser::newPayloadReceived(const uint8_t* data, size_t len, bool hasMarker)
 {
+	size_t headerSize = 1;
+
 	// Payload descriptor
 	uint8_t req = data[0];
 	if (firstPacket && !(req & SBit)) { /* Error */ }
 
-	size_t headerSize;
+	if (req & XBit) { // Extension byte is present
+		uint8_t optX = data[headerSize++];
+		if (optX & IBit) { // PictureID byte is present
+			uint8_t optI = data[headerSize++];
+			pictureID = optI >> 1;
+		}
+	}
+
 	// Payload header
 	if (firstPacket) {
 		firstPacket = false;
-
-		uint8_t o1 = data[1];
+		uint8_t o1 = data[headerSize];
 		showFrame = (o1 & 1);
 		isKeyFrame = (o1 & HBit);
 		o1 >>= Size0BitShift;
-		frameSize = o1 + 8 * data[2] + 2048 * data[3];
+		frameSize = o1 + 8 * data[headerSize + 1] + 2048 * data[headerSize + 2];
 
-		headerSize = 4;
-	} else {
-		headerSize = 1;
+		headerSize += 3;
 	}
 
 	buffer.insert(buffer.end(), data + headerSize, data + len);
 
 	if (hasMarker || buffer.size() >= frameSize) {
 		// Frame received
-		decoder->decodeFrame(buffer);
+		decoder->decodeFrame(buffer, pictureID);
 		buffer.clear();
 		firstPacket = true;
 	}
diff --git a/Swiften/ScreenSharing/VP8RTPParser.h b/Swiften/ScreenSharing/VP8RTPParser.h
index 1594c66..7f6a393 100644
--- a/Swiften/ScreenSharing/VP8RTPParser.h
+++ b/Swiften/ScreenSharing/VP8RTPParser.h
@@ -21,6 +21,8 @@ namespace Swift {
 
 		private:
 			static const uint8_t SBit = 1 << 4;
+			static const uint8_t XBit = 1 << 7;
+			static const uint8_t IBit = 1 << 7;
 			static const uint8_t HBit = 1 << 4;
 			static const uint8_t Size0BitShift = 5;
 
@@ -31,5 +33,6 @@ namespace Swift {
 			size_t frameSize;
 			bool isKeyFrame;
 			bool showFrame;
+			int pictureID;
 	};
 }
diff --git a/Swiften/ScreenSharing/VideoDecoder.h b/Swiften/ScreenSharing/VideoDecoder.h
index 810d5ae..fdec6b3 100644
--- a/Swiften/ScreenSharing/VideoDecoder.h
+++ b/Swiften/ScreenSharing/VideoDecoder.h
@@ -18,9 +18,10 @@ namespace Swift {
 			VideoDecoder() {}
 			virtual ~VideoDecoder() {}
 
-			virtual void decodeFrame(const std::vector<uint8_t>& frame) = 0;
+			virtual void decodeFrame(const std::vector<uint8_t>& frame, int pictureID) = 0;
 
 		public:
-			boost::signal<void (const Image&)> onNewImageDecoded;
+			boost::signal<void (int pictureID, bool success)> onNewFrameDecoded;
+			boost::signal<void (const Image&)> onNewImageAvailable;
 	};
 }
diff --git a/Swiften/ScreenSharing/VideoEncoder.h b/Swiften/ScreenSharing/VideoEncoder.h
index 718b59f..c28b6d1 100644
--- a/Swiften/ScreenSharing/VideoEncoder.h
+++ b/Swiften/ScreenSharing/VideoEncoder.h
@@ -19,5 +19,7 @@ namespace Swift {
 			virtual ~VideoEncoder() {}
 
 			virtual void encodeImage(const Image& frame) = 0;
+
+			virtual void handleRPSIFeedback(int /*pictureID*/) = 0;
 	};
 }