diff --git a/srtcore/buffer_snd.cpp b/srtcore/buffer_snd.cpp
index 26f885dd6..39e476271 100644
--- a/srtcore/buffer_snd.cpp
+++ b/srtcore/buffer_snd.cpp
@@ -355,7 +355,11 @@ int CSndBuffer::readData(CPacket& w_packet, steady_clock::time_point& w_srctime,
             continue;
         }
 
-        HLOGC(bslog.Debug, log << CONID() << "CSndBuffer: extracting packet size=" << readlen << " to send");
+        HLOGC(bslog.Debug, log << CONID() << "CSndBuffer: picked up packet to send: size=" << readlen
+                << " #" << w_packet.getMsgSeq()
+                << " %" << w_packet.m_iSeqNo
+                << " !" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));
+
         break;
     }
 
diff --git a/srtcore/common.h b/srtcore/common.h
index de42a7d83..bfc0c1d96 100644
--- a/srtcore/common.h
+++ b/srtcore/common.h
@@ -1430,6 +1430,23 @@ inline bool checkMappedIPv4(const sockaddr_in6& sa)
     return checkMappedIPv4(addr);
 }
 
+inline std::string FormatLossArray(const std::vector< std::pair<int32_t, int32_t> >& lra)
+{
+    std::ostringstream os;
+
+    os << "[ ";
+    for (std::vector< std::pair<int32_t, int32_t> >::const_iterator i = lra.begin(); i != lra.end(); ++i)
+    {
+        int len = CSeqNo::seqoff(i->first, i->second);
+        os << "%" << i->first;
+        if (len > 1)
+            os << "+" << len;
+        os << " ";
+    }
+
+    os << "]";
+    return os.str();
+}
 
 } // namespace srt
 
diff --git a/srtcore/core.cpp b/srtcore/core.cpp
index 084cad670..38d59876f 100644
--- a/srtcore/core.cpp
+++ b/srtcore/core.cpp
@@ -11338,7 +11338,7 @@ bool srt::CUDT::checkExpTimer(const steady_clock::time_point& currtime, int chec
         // Application will detect this when it calls any UDT methods next time.
         //
         HLOGC(xtlog.Debug,
-              log << CONID() << "CONNECTION EXPIRED after " << count_milliseconds(currtime - last_rsp_time) << "ms");
+              log << CONID() << "CONNECTION EXPIRED after " << FormatDuration<DUNIT_MS>(currtime - last_rsp_time) << " - BREAKING");
         m_bClosing       = true;
         m_bBroken        = true;
         m_iBrokenCounter = 30;
@@ -11566,6 +11566,7 @@ void srt::CUDT::completeBrokenConnectionDependencies(int errorcode)
     {
         // XXX This somehow can cause a deadlock
         // uglobal()->close(m_parent);
+        LOGC(smlog.Debug, log << "updateBrokenConnection...: BROKEN SOCKET @" << m_SocketID << " - CLOSING, to be removed from group.");
         m_parent->setBrokenClosed();
     }
 #endif
diff --git a/srtcore/core.h b/srtcore/core.h
index 1d48436fb..2fdbe4d12 100644
--- a/srtcore/core.h
+++ b/srtcore/core.h
@@ -389,6 +389,11 @@ class CUDT
         return (int32_t) sync::count_microseconds(from_time - tsStartTime);
     }
 
+    static void setPacketTS(CPacket& p, const time_point& start_time, const time_point& ts)
+    {
+        p.m_iTimeStamp = makeTS(ts, start_time);
+    }
+
     /// @brief Set the timestamp field of the packet using the provided value (no check)
     /// @param p the packet structure to set the timestamp on.
     /// @param ts timestamp to use as a source for packet timestamp.
diff --git a/srtcore/group.cpp b/srtcore/group.cpp
index 001dd4802..c6b92a0ff 100644
--- a/srtcore/group.cpp
+++ b/srtcore/group.cpp
@@ -278,8 +278,8 @@ CUDTGroup::CUDTGroup(SRT_GROUP_TYPE gtype)
     , m_iLastSchedMsgNo(SRT_MSGNO_NONE)
 {
     setupMutex(m_GroupLock, "Group");
-    setupMutex(m_RcvDataLock, "RcvData");
-    setupCond(m_RcvDataCond, "RcvData");
+    setupMutex(m_RcvDataLock, "G/RcvData");
+    setupCond(m_RcvDataCond, "G/RcvData");
     m_RcvEID = m_Global.m_EPoll.create(&m_RcvEpolld);
     m_SndEID = m_Global.m_EPoll.create(&m_SndEpolld);
 
@@ -861,7 +861,7 @@ void CUDTGroup::syncWithSocket(const CUDT& core, const HandshakeSide side)
     // Get the latency (possibly fixed against the opposite side)
     // from the first socket (core.m_iTsbPdDelay_ms),
     // and set it on the current socket.
-    set_latency(core.m_iTsbPdDelay_ms * int64_t(1000));
+    set_latency_us(core.m_iTsbPdDelay_ms * int64_t(1000));
 }
 
 void CUDTGroup::close()
diff --git a/srtcore/group.h b/srtcore/group.h
index c2863b44e..247423da3 100644
--- a/srtcore/group.h
+++ b/srtcore/group.h
@@ -611,7 +611,7 @@ class CUDTGroup
 
 private:
     // Fields required for SRT_GTYPE_BACKUP groups.
-    senderBuffer_t        m_SenderBuffer;
+    senderBuffer_t        m_SenderBuffer; // This mechanism is to be removed on group-common sndbuf
     int32_t               m_iSndOldestMsgNo; // oldest position in the sender buffer
     sync::atomic<int32_t> m_iSndAckedMsgNo;
     uint32_t              m_uOPT_MinStabilityTimeout_us;
@@ -800,7 +800,7 @@ class CUDTGroup
     SRTU_PROPERTY_RW_CHAIN(CUDTGroup, SRT_GROUP_TYPE, type, m_type);
     SRTU_PROPERTY_RW_CHAIN(CUDTGroup, int32_t, currentSchedSequence, m_iLastSchedSeqNo);
     SRTU_PROPERTY_RRW(std::set<int>&, epollset, m_sPollID);
-    SRTU_PROPERTY_RW_CHAIN(CUDTGroup, int64_t, latency, m_iTsbPdDelay_us);
+    SRTU_PROPERTY_RW_CHAIN(CUDTGroup, int64_t, latency_us, m_iTsbPdDelay_us);
     SRTU_PROPERTY_RO(bool, closing, m_bClosing);
 };
 
diff --git a/srtcore/handshake.h b/srtcore/handshake.h
index 93a351f39..c6a5731e4 100644
--- a/srtcore/handshake.h
+++ b/srtcore/handshake.h
@@ -311,6 +311,8 @@ class CHandShake
     // Applicable only when m_iVersion == HS_VERSION_SRT1
     int32_t flags() { return m_iType; }
 
+    bool v5orHigher() { return m_iVersion > 4; }
+
 public:
     int32_t m_iVersion;          // UDT version (HS_VERSION_* symbols)
     int32_t m_iType;             // UDT4: socket type (only UDT_DGRAM is valid); SRT1: extension flags
diff --git a/srtcore/list.cpp b/srtcore/list.cpp
index b6e70d39d..0a175ee9d 100644
--- a/srtcore/list.cpp
+++ b/srtcore/list.cpp
@@ -99,16 +99,7 @@ srt::CSndLossList::~CSndLossList()
 
 void srt::CSndLossList::traceState() const
 {
-    int pos = m_iHead;
-    while (pos != SRT_SEQNO_NONE)
-    {
-        std::cout << pos << ":[" << m_caSeq[pos].seqstart;
-        if (m_caSeq[pos].seqend != SRT_SEQNO_NONE)
-            std::cout << ", " << m_caSeq[pos].seqend;
-        std::cout << "], ";
-        pos = m_caSeq[pos].inext;
-    }
-    std::cout << "\n";
+    traceState(std::cout) << "\n";
 }
 
 int srt::CSndLossList::insert(int32_t seqno1, int32_t seqno2)
@@ -508,6 +499,10 @@ srt::CRcvLossList::~CRcvLossList()
 
 int srt::CRcvLossList::insert(int32_t seqno1, int32_t seqno2)
 {
+    SRT_ASSERT(seqno1 != SRT_SEQNO_NONE && seqno2 != SRT_SEQNO_NONE);
+    // Make sure that seqno2 isn't earlier than seqno1.
+    SRT_ASSERT(CSeqNo::seqcmp(seqno1, seqno2) <= 0);
+
     // Data to be inserted must be larger than all those in the list
     if (m_iLargestSeq != SRT_SEQNO_NONE && CSeqNo::seqcmp(seqno1, m_iLargestSeq) <= 0)
     {
diff --git a/srtcore/list.h b/srtcore/list.h
index 8f921c698..40b8ee0c9 100644
--- a/srtcore/list.h
+++ b/srtcore/list.h
@@ -84,6 +84,25 @@ class CSndLossList
     /// @return The seq. no. or -1 if the list is empty.
     int32_t popLostSeq();
 
+    template <class Stream>
+    Stream& traceState(Stream& sout) const
+    {
+        int pos = m_iHead;
+        while (pos != SRT_SEQNO_NONE)
+        {
+            sout << "[" << pos << "]:" << m_caSeq[pos].seqstart;
+            if (m_caSeq[pos].seqend != SRT_SEQNO_NONE)
+                sout << ":" << m_caSeq[pos].seqend;
+            if (m_caSeq[pos].inext == -1)
+                sout << "=|";
+            else
+                sout << "->[" << m_caSeq[pos].inext << "]";
+            sout << ", ";
+            pos = m_caSeq[pos].inext;
+        }
+        sout << " {len:" << m_iLength << " head:" << m_iHead << " last:" << m_iLastInsertPos << "}";
+        return sout;
+    }
     void traceState() const;
 
     // Debug/unittest support.
diff --git a/srtcore/logging.h b/srtcore/logging.h
index e90ad4ac2..5867c41ae 100644
--- a/srtcore/logging.h
+++ b/srtcore/logging.h
@@ -75,7 +75,7 @@ written by
 #define HLOGP LOGP
 #define HLOGF LOGF
 
-#define IF_HEAVY_LOGGING(instr) instr
+#define IF_HEAVY_LOGGING(instr,...) instr,##__VA_ARGS__
 
 #else
 
diff --git a/srtcore/socketconfig.cpp b/srtcore/socketconfig.cpp
index 5c5b8e090..bd76ccc19 100644
--- a/srtcore/socketconfig.cpp
+++ b/srtcore/socketconfig.cpp
@@ -52,6 +52,27 @@ written by
 #include "srt.h"
 #include "socketconfig.h"
 
+namespace srt
+{
+int RcvBufferSizeOptionToValue(int val, int flightflag, int mss)
+{
+    // Mimimum recv buffer size is 32 packets
+    const int mssin_size = mss - CPacket::UDP_HDR_SIZE;
+
+    int bufsize;
+    if (val > mssin_size * CSrtConfig::DEF_MIN_FLIGHT_PKT)
+        bufsize = val / mssin_size;
+    else
+        bufsize = CSrtConfig::DEF_MIN_FLIGHT_PKT;
+
+    // recv buffer MUST not be greater than FC size
+    if (bufsize > flightflag)
+        bufsize = flightflag;
+
+    return bufsize;
+}
+}
+
 using namespace srt;
 extern const int32_t SRT_DEF_VERSION = SrtParseVersion(SRT_VERSION);
 
@@ -122,17 +143,7 @@ struct CSrtConfigSetter<SRTO_RCVBUF>
         if (val <= 0)
             throw CUDTException(MJ_NOTSUP, MN_INVAL, 0);
 
-        // Mimimum recv buffer size is 32 packets
-        const int mssin_size = co.iMSS - CPacket::UDP_HDR_SIZE;
-
-        if (val > mssin_size * co.DEF_MIN_FLIGHT_PKT)
-            co.iRcvBufSize = val / mssin_size;
-        else
-            co.iRcvBufSize = co.DEF_MIN_FLIGHT_PKT;
-
-        // recv buffer MUST not be greater than FC size
-        if (co.iRcvBufSize > co.iFlightFlagSize)
-            co.iRcvBufSize = co.iFlightFlagSize;
+        co.iRcvBufSize = srt::RcvBufferSizeOptionToValue(val, co.iFlightFlagSize, co.iMSS);
     }
 };
 
diff --git a/srtcore/socketconfig.h b/srtcore/socketconfig.h
index 403616edf..52e6101d4 100644
--- a/srtcore/socketconfig.h
+++ b/srtcore/socketconfig.h
@@ -379,6 +379,9 @@ inline bool cast_optval(const void* optval, int optlen)
     return false;
 }
 
+
+int RcvBufferSizeOptionToValue(int optval, int flightflag, int mss);
+
 } // namespace srt
 
 struct SRT_SocketOptionObject
diff --git a/srtcore/sync.h b/srtcore/sync.h
index 87be6f458..c5a247f87 100644
--- a/srtcore/sync.h
+++ b/srtcore/sync.h
@@ -771,7 +771,7 @@ struct DurationUnitName<DUNIT_S>
 template<eDurationUnit UNIT>
 inline std::string FormatDuration(const steady_clock::duration& dur)
 {
-    return Sprint(DurationUnitName<UNIT>::count(dur)) + DurationUnitName<UNIT>::name();
+    return Sprint(std::fixed, DurationUnitName<UNIT>::count(dur)) + DurationUnitName<UNIT>::name();
 }
 
 inline std::string FormatDuration(const steady_clock::duration& dur)
diff --git a/srtcore/tsbpd_time.cpp b/srtcore/tsbpd_time.cpp
index 046c90b74..162fc7ac7 100644
--- a/srtcore/tsbpd_time.cpp
+++ b/srtcore/tsbpd_time.cpp
@@ -220,7 +220,16 @@ CTsbpdTime::time_point CTsbpdTime::getTsbPdTimeBase(uint32_t timestamp_us) const
 
 CTsbpdTime::time_point CTsbpdTime::getPktTsbPdTime(uint32_t usPktTimestamp) const
 {
-    return getPktTsbPdBaseTime(usPktTimestamp) + m_tdTsbPdDelay + microseconds_from(m_DriftTracer.drift());
+    time_point value = getPktTsbPdBaseTime(usPktTimestamp) + m_tdTsbPdDelay + microseconds_from(m_DriftTracer.drift());
+
+    /*
+    HLOGC(brlog.Debug, log << "getPktTsbPdTime:"
+            << " BASE=" << FormatTime(m_tsTsbPdTimeBase)
+            << " TS=" << usPktTimestamp << "us, lat=" << FormatDuration<DUNIT_US>(m_tdTsbPdDelay)
+            << " DRF=" << m_DriftTracer.drift() << "us = " << FormatTime(value));
+            */
+
+    return value;
 }
 
 CTsbpdTime::time_point CTsbpdTime::getPktTsbPdBaseTime(uint32_t usPktTimestamp) const
diff --git a/srtcore/utilities.h b/srtcore/utilities.h
index 31e05b205..5f9d62898 100644
--- a/srtcore/utilities.h
+++ b/srtcore/utilities.h
@@ -432,7 +432,7 @@ class FixedArray
     const T& operator[](size_t index) const
     {
         if (index >= m_size)
-            raise_expection(index);
+            throw_invalid_index(index);
 
         return m_entries[index];
     }
@@ -440,7 +440,7 @@ class FixedArray
     T& operator[](size_t index)
     {
         if (index >= m_size)
-            raise_expection(index);
+            throw_invalid_index(index);
 
         return m_entries[index];
     }
@@ -448,7 +448,7 @@ class FixedArray
     const T& operator[](int index) const
     {
         if (index < 0 || static_cast<size_t>(index) >= m_size)
-            raise_expection(index);
+            throw_invalid_index(index);
 
         return m_entries[index];
     }
@@ -456,7 +456,7 @@ class FixedArray
     T& operator[](int index)
     {
         if (index < 0 || static_cast<size_t>(index) >= m_size)
-            raise_expection(index);
+            throw_invalid_index(index);
 
         return m_entries[index];
     }
@@ -478,7 +478,7 @@ class FixedArray
     FixedArray(const FixedArray<T>& );
     FixedArray<T>& operator=(const FixedArray<T>&);
 
-    void raise_expection(int i) const
+    void throw_invalid_index(int i) const
     {
         std::stringstream ss;
         ss << "Index " << i << "out of range";
@@ -534,6 +534,34 @@ namespace srt_pair_op
     }
 }
 
+namespace any_op
+{
+    template <class T>
+    struct AnyProxy
+    {
+        const T& value;
+        bool result;
+
+        AnyProxy(const T& x, bool res): value(x), result(res) {}
+
+        AnyProxy<T>& operator,(const T& val)
+        {
+            if (result)
+                return *this;
+            result = value == val;
+            return *this;
+        }
+
+        operator bool() { return result; }
+    };
+
+    template <class T> inline
+    AnyProxy<T> EqualAny(const T& checked_val)
+    {
+        return AnyProxy<T>(checked_val, false);
+    }
+}
+
 #if HAVE_CXX11
 
 template <class In>
@@ -666,6 +694,15 @@ inline std::string Sprint(const Arg1& arg)
     return sout.str();
 }
 
+// Ok, let it be 2-arg, in case when a manipulator is needed
+template <class Arg1, class Arg2>
+inline std::string Sprint(const Arg1& arg1, const Arg2& arg2)
+{
+    std::ostringstream sout;
+    sout << arg1 << arg2;
+    return sout.str();
+}
+
 template <class Container> inline
 std::string Printable(const Container& in)
 {
@@ -748,6 +785,32 @@ inline void insert_uniq(std::vector<Value>& v, const ArgValue& val)
     v.push_back(val);
 }
 
+template <class Type1, class Type2>
+inline std::pair<Type1&, Type2&> Tie(Type1& var1, Type2& var2)
+{
+    return std::pair<Type1&, Type2&>(var1, var2);
+}
+
+// This can be used in conjunction with Tie to simplify the code
+// in loops around a whole container:
+// list<string>::const_iterator it, end;
+// Tie(it, end) = All(list_container);
+template<class Container>
+std::pair<typename Container::iterator, typename Container::iterator>
+inline All(Container& c) { return std::make_pair(c.begin(), c.end()); }
+
+template<class Container>
+std::pair<typename Container::const_iterator, typename Container::const_iterator>
+inline All(const Container& c) { return std::make_pair(c.begin(), c.end()); }
+
+
+template <class Container, class Value>
+inline void FringeValues(const Container& from, std::map<Value, size_t>& out)
+{
+    for (typename Container::const_iterator i = from.begin(); i != from.end(); ++i)
+        ++out[*i];
+}
+
 template <class Signature>
 struct CallbackHolder
 {
@@ -1058,11 +1121,11 @@ inline ValueType avg_iir_w(ValueType old_value, ValueType new_value, size_t new_
 // This relies only on a convention, which is the following:
 //
 // V x = object.prop(); <-- get the property's value
-// object.prop(x); <-- set the property a value
+// object.set_prop(x); <-- set the property a value
 //
 // Properties might be also chained when setting:
 //
-// object.prop1(v1).prop2(v2).prop3(v3);
+// object.set_prop1(v1).set_prop2(v2).set_prop3(v3);
 //
 // Properties may be defined various even very complicated
 // ways, which is simply providing a method with body. In order
diff --git a/testing/testmedia.cpp b/testing/testmedia.cpp
index 6fd22e468..2d6635288 100755
--- a/testing/testmedia.cpp
+++ b/testing/testmedia.cpp
@@ -963,16 +963,36 @@ void TransmitGroupSocketConnect(void* srtcommon, SRTSOCKET sock, int error, cons
     Verb() << " IPE: LINK NOT FOUND???]";
 }
 
-void SrtCommon::OpenGroupClient()
+SRT_GROUP_TYPE ResolveGroupType(const string& name)
 {
-    SRT_GROUP_TYPE type = SRT_GTYPE_UNDEFINED;
+    static struct
+    {
+        string name;
+        SRT_GROUP_TYPE type;
+    } table [] {
+#define E(n) {#n, SRT_GTYPE_##n}
+        E(BROADCAST),
+        E(BACKUP)
 
-    // Resolve group type.
-    if (m_group_type == "broadcast")
-        type = SRT_GTYPE_BROADCAST;
-    else if (m_group_type == "backup")
-        type = SRT_GTYPE_BACKUP;
-    else
+#undef E
+    };
+
+    typedef int charxform(int c);
+
+    string uname;
+    transform(name.begin(), name.end(), back_inserter(uname), (charxform*)(&toupper));
+
+    for (auto& x: table)
+        if (x.name == uname)
+            return x.type;
+
+    return SRT_GTYPE_UNDEFINED;
+}
+
+void SrtCommon::OpenGroupClient()
+{
+    SRT_GROUP_TYPE type = ResolveGroupType(m_group_type);
+    if (type == SRT_GTYPE_UNDEFINED)
     {
         Error("With //group, type='" + m_group_type + "' undefined");
     }