Add more EDI input improvements

9 files changed, 1725 insertions, 0 deletions

diff --git a/lib/edi/PFT.cpp b/lib/edi/PFT.cpp
new file mode 100644
index 0000000..aff7929
--- /dev/null
+++ b/lib/edi/PFT.cpp
@@ -0,0 +1,574 @@
+/* ------------------------------------------------------------------
+ * Copyright (C) 2017 AVT GmbH - Fabien Vercasson
+ * Copyright (C) 2017 Matthias P. Braendli
+ *                    matthias.braendli@mpb.li
+ *
+ * http://opendigitalradio.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ * -------------------------------------------------------------------
+ */
+
+#include <stdio.h>
+#include <cassert>
+#include <cstring>
+#include <sstream>
+#include <stdexcept>
+#include <algorithm>
+#include "crc.h"
+#include "PFT.hpp"
+#include "Log.h"
+#include "buffer_unpack.hpp"
+extern "C" {
+#include "fec/fec.h"
+}
+
+namespace EdiDecoder {
+namespace PFT {
+
+using namespace std;
+
+const findex_t NUM_AFBUILDERS_TO_KEEP = 10;
+
+static bool checkCRC(const uint8_t *buf, size_t size)
+{
+    const uint16_t crc_from_packet = read_16b(buf + size - 2);
+    uint16_t crc_calc = 0xffff;
+    crc_calc = crc16(crc_calc, buf, size - 2);
+    crc_calc ^= 0xffff;
+
+    return crc_from_packet == crc_calc;
+}
+
+class FECDecoder {
+    public:
+        FECDecoder() {
+            m_rs_handler = init_rs_char(
+                    symsize, gfPoly, firstRoot, primElem, nroots, pad);
+        }
+        FECDecoder(const FECDecoder& other) = delete;
+        FECDecoder& operator=(const FECDecoder& other) = delete;
+        ~FECDecoder() {
+            free_rs_char(m_rs_handler);
+        }
+
+        // return -1 in case of failure, non-negative value if errors
+        // were corrected.
+        // Known positions of erasures should be given in eras_pos to
+        // improve decoding probability. After calling this function
+        // eras_pos will contain the positions of the corrected errors.
+        int decode(vector<uint8_t> &data, vector<int> &eras_pos) {
+            assert(data.size() == N);
+            const size_t no_eras = eras_pos.size();
+
+            eras_pos.resize(nroots);
+            int num_err = decode_rs_char(m_rs_handler, data.data(),
+                    eras_pos.data(), no_eras);
+            if (num_err > 0) {
+                eras_pos.resize(num_err);
+            }
+            return num_err;
+        }
+
+        // return -1 in case of failure, non-negative value if errors
+        // were corrected. No known erasures.
+        int decode(vector<uint8_t> &data) {
+            assert(data.size() == N);
+            int num_err = decode_rs_char(m_rs_handler, data.data(), nullptr, 0);
+            return num_err;
+        }
+
+    private:
+        void* m_rs_handler;
+
+        const int firstRoot = 1; // Discovered by analysing EDI dump
+        const int gfPoly = 0x11d;
+
+        // The encoding has to be 255, 207 always, because the chunk has to
+        // be padded at the end, and not at the beginning as libfec would
+        // do
+        const size_t N = 255;
+        const size_t K = 207;
+        const int primElem = 1;
+        const int symsize = 8;
+        const size_t nroots = N - K; // For EDI PFT, this must be 48
+        const size_t pad = ((1 << symsize) - 1) - N; // is 255-N
+
+};
+
+size_t Fragment::loadData(const std::vector<uint8_t> &buf)
+{
+    const size_t header_len = 14;
+    if (buf.size() < header_len) {
+        return 0;
+    }
+
+    size_t index = 0;
+
+    // Parse PFT Fragment Header (ETSI TS 102 821 V1.4.1 ch7.1)
+    if (not (buf[0] == 'P' and buf[1] == 'F') ) {
+        throw invalid_argument("Invalid PFT SYNC bytes");
+    }
+    index += 2; // Psync
+
+    _Pseq = read_16b(buf.begin()+index); index += 2;
+    _Findex = read_24b(buf.begin()+index); index += 3;
+    _Fcount = read_24b(buf.begin()+index); index += 3;
+    _FEC = unpack1bit(buf[index], 0);
+    _Addr = unpack1bit(buf[index], 1);
+    _Plen = read_16b(buf.begin()+index) & 0x3FFF; index += 2;
+
+    const size_t required_len = header_len +
+        (_FEC ? 1 : 0) +
+        (_Addr ? 2 : 0) +
+        2; // CRC
+    if (buf.size() < required_len) {
+        return 0;
+    }
+
+    // Optional RS Header
+    _RSk = 0;
+    _RSz = 0;
+    if (_FEC) {
+        _RSk = buf[index]; index += 1;
+        _RSz = buf[index]; index += 1;
+    }
+
+    // Optional transport header
+    _Source = 0;
+    _Dest = 0;
+    if (_Addr) {
+        _Source = read_16b(buf.begin()+index); index += 2;
+        _Dest = read_16b(buf.begin()+index); index += 2;
+    }
+
+    index += 2;
+    const bool crc_valid = checkCRC(buf.data(), index);
+    const bool buf_has_enough_data = (buf.size() >= index + _Plen);
+
+    if (not buf_has_enough_data) {
+        return 0;
+    }
+
+    _valid = ((not _FEC) or crc_valid) and buf_has_enough_data;
+
+#if 0
+    if (!_valid) {
+        stringstream ss;
+        ss << "Invalid PF fragment: ";
+        if (_FEC) {
+            ss << " RSk=" << (uint32_t)_RSk << " RSz=" << (uint32_t)_RSz;
+        }
+
+        if (_Addr) {
+            ss << " Source=" << _Source << " Dest=" << _Dest;
+        }
+        etiLog.log(debug, "%s\n", ss.str().c_str());
+    }
+#endif
+
+    _payload.clear();
+    if (_valid) {
+        copy( buf.begin()+index,
+                buf.begin()+index+_Plen,
+                back_inserter(_payload));
+        index += _Plen;
+    }
+
+    return index;
+}
+
+
+AFBuilder::AFBuilder(pseq_t Pseq, findex_t Fcount, size_t lifetime)
+{
+    _Pseq = Pseq;
+    _Fcount = Fcount;
+    assert(lifetime > 0);
+    lifeTime = lifetime;
+}
+
+void AFBuilder::pushPFTFrag(const Fragment &frag)
+{
+    if (_Pseq != frag.Pseq() or _Fcount != frag.Fcount()) {
+        throw invalid_argument("Invalid PFT fragment Pseq or Fcount");
+    }
+    const auto Findex = frag.Findex();
+    const bool fragment_already_received = _fragments.count(Findex);
+
+    if (not fragment_already_received)
+    {
+        _fragments[Findex] = frag;
+    }
+}
+
+bool Fragment::checkConsistency(const Fragment& other) const
+{
+    /* Consistency check, TS 102 821 Clause 7.3.2.
+     *
+     * Every PFT Fragment produced from a single AF or RS Packet shall have
+     * the same values in all of the PFT Header fields except for the Findex,
+     * Plen and HCRC fields.
+     */
+
+    return other._Fcount == _Fcount and
+        other._FEC == _FEC and
+        other._RSk == _RSk and
+        other._RSz == _RSz and
+        other._Addr == _Addr and
+        other._Source == _Source and
+        other._Dest == _Dest and
+
+        /* The Plen field of all fragments shall be the s for the initial f-1
+         * fragments and s - (L%f) for the final fragment.
+         * Note that when Reed Solomon has been used, all fragments will be of
+         * length s.
+         */
+        (_FEC ? other._Plen == _Plen : true);
+}
+
+
+AFBuilder::decode_attempt_result_t AFBuilder::canAttemptToDecode() const
+{
+    if (_fragments.empty()) {
+        return AFBuilder::decode_attempt_result_t::no;
+    }
+
+    if (_fragments.size() == _Fcount) {
+        return AFBuilder::decode_attempt_result_t::yes;
+    }
+
+    /* Check that all fragments are consistent */
+    const Fragment& first = _fragments.begin()->second;
+    if (not std::all_of(_fragments.begin(), _fragments.end(),
+            [&](const pair<int, Fragment>& pair) {
+                const Fragment& frag = pair.second;
+                return first.checkConsistency(frag) and _Pseq == frag.Pseq();
+            }) ) {
+        throw invalid_argument("Inconsistent PFT fragments");
+    }
+
+    // Calculate the minimum number of fragments necessary to apply FEC.
+    // This can't be done with the last fragment that may have a
+    // smaller size
+    // ETSI TS 102 821 V1.4.1 ch 7.4.4
+    auto frag_it = _fragments.begin();
+    if (frag_it->second.Fcount() == _Fcount - 1) {
+        frag_it++;
+
+        if (frag_it == _fragments.end()) {
+            return AFBuilder::decode_attempt_result_t::no;
+        }
+    }
+
+    const Fragment& frag = frag_it->second;
+
+    if ( frag.FEC() )
+    {
+        const uint16_t _Plen = frag.Plen();
+
+        /* max number of RS chunks that may have been sent */
+        const uint32_t _cmax = (_Fcount*_Plen) / (frag.RSk()+48);
+        assert(_cmax > 0);
+
+        /* Receiving _rxmin fragments does not guarantee that decoding
+         * will succeed! */
+        const uint32_t _rxmin = _Fcount - (_cmax*48)/_Plen;
+
+        if (_fragments.size() >= _rxmin) {
+            return AFBuilder::decode_attempt_result_t::maybe;
+        }
+    }
+
+    return AFBuilder::decode_attempt_result_t::no;
+}
+
+std::vector<uint8_t> AFBuilder::extractAF() const
+{
+    if (not _af_packet.empty()) {
+        return _af_packet;
+    }
+
+    bool ok = false;
+
+    if (canAttemptToDecode() != AFBuilder::decode_attempt_result_t::no) {
+
+        auto frag_it = _fragments.begin();
+        if (frag_it->second.Fcount() == _Fcount - 1) {
+            frag_it++;
+
+            if (frag_it == _fragments.end()) {
+                throw std::runtime_error("Invalid attempt at extracting AF");
+            }
+        }
+
+        const Fragment& ref_frag = frag_it->second;
+        const auto RSk = ref_frag.RSk();
+        const auto RSz = ref_frag.RSz();
+        const auto Plen = ref_frag.Plen();
+
+        if ( ref_frag.FEC() )
+        {
+            const uint32_t cmax = (_Fcount*Plen) / (RSk+48);
+
+            // Keep track of erasures (missing fragments) for
+            // every chunk
+            map<int, vector<int> > erasures;
+
+
+            // Assemble fragments into a RS block, immediately
+            // deinterleaving it.
+            vector<uint8_t> rs_block(Plen * _Fcount);
+            for (size_t j = 0; j < _Fcount; j++) {
+                const bool fragment_present = _fragments.count(j);
+                if (fragment_present) {
+                    const auto& fragment = _fragments.at(j).payload();
+
+                    if (j != _Fcount - 1 and fragment.size() != Plen) {
+                        throw runtime_error("Incorrect fragment length " +
+                                to_string(fragment.size()) + " " +
+                                to_string(Plen));
+                    }
+
+                    if (j == _Fcount - 1 and fragment.size() > Plen) {
+                        throw runtime_error("Incorrect last fragment length " +
+                                to_string(fragment.size()) + " " +
+                                to_string(Plen));
+                    }
+
+                    size_t k = 0;
+                    for (; k < fragment.size(); k++) {
+                        rs_block[k * _Fcount + j] = fragment[k];
+                    }
+
+                    for (; k < Plen; k++) {
+                        rs_block[k * _Fcount + j] = 0x00;
+                    }
+                }
+                else {
+                    // fill with zeros if fragment is missing
+                    for (size_t k = 0; k < Plen; k++) {
+                        rs_block[k * _Fcount + j] = 0x00;
+
+                        const size_t chunk_ix = (k * _Fcount + j) / (RSk + 48);
+                        const size_t chunk_offset = (k * _Fcount + j) % (RSk + 48);
+                        erasures[chunk_ix].push_back(chunk_offset);
+                    }
+                }
+            }
+
+            // The RS block is a concatenation of chunks of RSk bytes + 48 parity
+            // followed by RSz padding
+
+            FECDecoder fec;
+            for (size_t i = 0; i < cmax; i++) {
+                // We need to pad the chunk ourself
+                vector<uint8_t> chunk(255);
+                const auto& block_begin = rs_block.begin() + (RSk + 48) * i;
+                copy(block_begin, block_begin + RSk, chunk.begin());
+                // bytes between RSk and 207 are 0x00 already
+                copy(block_begin + RSk, block_begin + RSk + 48,
+                        chunk.begin() + 207);
+
+                int errors_corrected = -1;
+                if (erasures.count(i)) {
+                    errors_corrected = fec.decode(chunk, erasures[i]);
+                }
+                else {
+                    errors_corrected = fec.decode(chunk);
+                }
+
+                if (errors_corrected == -1) {
+                    _af_packet.clear();
+                    return {};
+                }
+
+#if 0
+                if (errors_corrected > 0) {
+                    etiLog.log(debug, "Corrected %d errors at ", errors_corrected);
+                    for (const auto &index : erasures[i]) {
+                        etiLog.log(debug, " %d", index);
+                    }
+                    etiLog.log(debug, "\n");
+                }
+#endif
+
+                _af_packet.insert(_af_packet.end(), chunk.begin(), chunk.begin() + RSk);
+            }
+
+            _af_packet.resize(_af_packet.size() - RSz);
+        }
+        else {
+            // No FEC: just assemble fragments
+
+            for (size_t j = 0; j < _Fcount; ++j) {
+                const bool fragment_present = _fragments.count(j);
+                if (fragment_present)
+                {
+                    const auto& fragment = _fragments.at(j);
+
+                    _af_packet.insert(_af_packet.end(),
+                       fragment.payload().begin(),
+                       fragment.payload().end());
+                }
+                else {
+                    throw logic_error("Missing fragment");
+                }
+            }
+        }
+
+        // EDI specific, must have a CRC.
+        if( _af_packet.size() >= 12 ) {
+            ok = checkCRC(_af_packet.data(), _af_packet.size());
+
+            if (not ok) {
+                etiLog.log(debug, "Too many errors to reconstruct AF from %zu/%u"
+                        " PFT fragments\n", _fragments.size(), _Fcount);
+            }
+        }
+    }
+
+    if (not ok) {
+        _af_packet.clear();
+    }
+
+    return _af_packet;
+}
+
+std::string AFBuilder::visualise() const
+{
+    stringstream ss;
+    ss << "|";
+    for (size_t i = 0; i < _Fcount; i++) {
+        if (_fragments.count(i)) {
+            ss << ".";
+        }
+        else {
+            ss << " ";
+        }
+    }
+    ss << "| " << AFBuilder::dar_to_string(canAttemptToDecode()) << " " << lifeTime;
+    return ss.str();
+}
+
+void PFT::pushPFTFrag(const Fragment &fragment)
+{
+    // Start decoding the first pseq we receive. In normal
+    // operation without interruptions, the map should
+    // never become empty
+    if (m_afbuilders.empty()) {
+        m_next_pseq = fragment.Pseq();
+        etiLog.log(debug,"Initialise next_pseq to %u\n", m_next_pseq);
+    }
+
+    if (m_afbuilders.count(fragment.Pseq()) == 0) {
+        // The AFBuilder wants to know the lifetime in number of fragments,
+        // we know the delay in number of AF packets. Every AF packet
+        // is cut into Fcount fragments.
+        const size_t lifetime = fragment.Fcount() * m_max_delay;
+
+        // Build the afbuilder in the map in-place
+        m_afbuilders.emplace(std::piecewise_construct,
+                /* key */
+                std::forward_as_tuple(fragment.Pseq()),
+                /* builder */
+                std::forward_as_tuple(fragment.Pseq(), fragment.Fcount(), lifetime));
+    }
+
+    auto& p = m_afbuilders.at(fragment.Pseq());
+    p.pushPFTFrag(fragment);
+
+    if (m_verbose) {
+        etiLog.log(debug, "Got frag %u:%u, afbuilders: ",
+                fragment.Pseq(), fragment.Findex());
+        for (const auto &k : m_afbuilders) {
+            const bool isNextPseq = (m_next_pseq == k.first);
+            etiLog.level(debug) << (isNextPseq ? "->" : "  ") <<
+                k.first << " " << k.second.visualise();
+        }
+    }
+}
+
+
+std::vector<uint8_t> PFT::getNextAFPacket()
+{
+    if (m_afbuilders.count(m_next_pseq) == 0) {
+        if (m_afbuilders.size() > m_max_delay) {
+            m_afbuilders.clear();
+            etiLog.level(debug) << " Reinit";
+        }
+
+        return {};
+    }
+
+    auto &builder = m_afbuilders.at(m_next_pseq);
+
+    using dar_t = AFBuilder::decode_attempt_result_t;
+
+    if (builder.canAttemptToDecode() == dar_t::yes) {
+        auto afpacket = builder.extractAF();
+        assert(not afpacket.empty());
+        incrementNextPseq();
+        return afpacket;
+    }
+    else if (builder.canAttemptToDecode() == dar_t::maybe) {
+        if (builder.lifeTime > 0) {
+            builder.lifeTime--;
+        }
+
+        if (builder.lifeTime == 0) {
+            // Attempt Reed-Solomon decoding
+            auto afpacket = builder.extractAF();
+
+            if (afpacket.empty()) {
+                etiLog.log(debug,"pseq %d timed out after RS", m_next_pseq);
+            }
+            incrementNextPseq();
+            return afpacket;
+        }
+    }
+    else {
+        if (builder.lifeTime > 0) {
+            builder.lifeTime--;
+        }
+
+        if (builder.lifeTime == 0) {
+            etiLog.log(debug, "pseq %d timed out\n", m_next_pseq);
+            incrementNextPseq();
+        }
+    }
+
+    return {};
+}
+
+void PFT::setMaxDelay(size_t num_af_packets)
+{
+    m_max_delay = num_af_packets;
+}
+
+void PFT::setVerbose(bool enable)
+{
+    m_verbose = enable;
+}
+
+void PFT::incrementNextPseq()
+{
+    if (m_afbuilders.count(m_next_pseq - NUM_AFBUILDERS_TO_KEEP) > 0) {
+        m_afbuilders.erase(m_next_pseq - NUM_AFBUILDERS_TO_KEEP);
+    }
+
+    m_next_pseq++;
+}
+
+}
+}
diff --git a/lib/edi/PFT.hpp b/lib/edi/PFT.hpp
new file mode 100644
index 0000000..779509b
--- /dev/null
+++ b/lib/edi/PFT.hpp
@@ -0,0 +1,166 @@
+/* ------------------------------------------------------------------
+ * Copyright (C) 2017 AVT GmbH - Fabien Vercasson
+ * Copyright (C) 2017 Matthias P. Braendli
+ *                    matthias.braendli@mpb.li
+ *
+ * http://opendigitalradio.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ * -------------------------------------------------------------------
+ */
+
+#pragma once
+#include <stdio.h>
+#include <vector>
+#include <map>
+#include <stdint.h>
+
+namespace EdiDecoder {
+namespace PFT {
+
+using pseq_t = uint16_t;
+using findex_t = uint32_t; // findex is a 24-bit value
+
+class Fragment
+{
+    public:
+        // Load the data for one fragment from buf into
+        // the Fragment.
+        // \returns the number of bytes of useful data found in buf
+        // A non-zero return value doesn't imply a valid fragment
+        // the isValid() method must be used to verify this.
+        size_t loadData(const std::vector<uint8_t> &buf);
+
+        bool isValid() const { return _valid; }
+        pseq_t Pseq() const { return _Pseq; }
+        findex_t Findex() const { return _Findex; }
+        findex_t Fcount() const { return _Fcount; }
+        bool FEC() const { return _FEC; }
+        uint16_t Plen() const { return _Plen; }
+        uint8_t RSk() const { return _RSk; }
+        uint8_t RSz() const { return _RSz; }
+        const std::vector<uint8_t>& payload() const
+            { return _payload; }
+
+        bool checkConsistency(const Fragment& other) const;
+
+    private:
+        std::vector<uint8_t> _payload;
+
+        pseq_t _Pseq = 0;
+        findex_t _Findex = 0;
+        findex_t _Fcount = 0;
+        bool _FEC = false;
+        bool _Addr = false;
+        uint16_t _Plen = 0;
+        uint8_t _RSk = 0;
+        uint8_t _RSz = 0;
+        uint16_t _Source = 0;
+        uint16_t _Dest = 0;
+        bool _valid = false;
+};
+
+/* The AFBuilder collects Fragments and builds an Application Frame
+ * out of them. It does error correction if necessary
+ */
+class AFBuilder
+{
+    public:
+        enum class decode_attempt_result_t {
+            yes,   // The AF packet can be build because all fragments are present
+            maybe, // RS decoding may correctly decode the AF packet
+            no,    // Not enough fragments present to permit RS
+        };
+
+        static std::string dar_to_string(decode_attempt_result_t dar) {
+            switch (dar) {
+                case decode_attempt_result_t::yes: return "y";
+                case decode_attempt_result_t::no: return "n";
+                case decode_attempt_result_t::maybe: return "m";
+            }
+            return "?";
+        }
+
+        AFBuilder(pseq_t Pseq, findex_t Fcount, size_t lifetime);
+
+        void pushPFTFrag(const Fragment &frag);
+
+        /* Assess if it may be possible to decode this AF packet */
+        decode_attempt_result_t canAttemptToDecode() const;
+
+        /* Try to build the AF with received fragments.
+         * Apply error correction if necessary (missing packets/CRC errors)
+         * \return an empty vector if building the AF is not possible
+         */
+        std::vector<uint8_t> extractAF(void) const;
+
+        std::pair<findex_t, findex_t>
+            numberOfFragments(void) const {
+                return {_fragments.size(), _Fcount};
+            }
+
+        std::string visualise(void) const;
+
+        /* The user of this instance can keep track of the lifetime of this
+         * builder
+         */
+        size_t lifeTime;
+
+    private:
+
+        // A map from fragment index to fragment
+        std::map<findex_t, Fragment> _fragments;
+
+        // cached version of decoded AF packet
+        mutable std::vector<uint8_t> _af_packet;
+
+        pseq_t _Pseq;
+        findex_t _Fcount;
+};
+
+class PFT
+{
+    public:
+        void pushPFTFrag(const Fragment &fragment);
+
+        /* Try to build the AF packet for the next pseq. This might
+         * skip one or more pseq according to the maximum delay setting.
+         *
+         * \return an empty vector if building the AF is not possible
+         */
+        std::vector<uint8_t> getNextAFPacket(void);
+
+        /* Set the maximum delay in number of AF Packets before we
+         * abandon decoding a given pseq.
+         */
+        void setMaxDelay(size_t num_af_packets);
+
+        /* Enable verbose fprintf */
+        void setVerbose(bool enable);
+
+    private:
+        void incrementNextPseq(void);
+
+        pseq_t m_next_pseq;
+        size_t m_max_delay = 10; // in AF packets
+
+        // Keep one AFBuilder for each Pseq
+        std::map<pseq_t, AFBuilder> m_afbuilders;
+
+        bool m_verbose = 0;
+};
+
+}
+
+}
diff --git a/lib/edi/STIDecoder.cpp b/lib/edi/STIDecoder.cpp
new file mode 100644
index 0000000..ca8cead
--- /dev/null
+++ b/lib/edi/STIDecoder.cpp
@@ -0,0 +1,191 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include "STIDecoder.hpp"
+#include "buffer_unpack.hpp"
+#include "crc.h"
+#include "Log.h"
+#include <stdio.h>
+#include <cassert>
+#include <sstream>
+
+namespace EdiDecoder {
+
+using namespace std;
+
+STIDecoder::STIDecoder(STIDataCollector& data_collector, bool verbose) :
+    m_data_collector(data_collector),
+    m_dispatcher(std::bind(&STIDecoder::packet_completed, this), verbose)
+{
+    using std::placeholders::_1;
+    using std::placeholders::_2;
+    m_dispatcher.register_tag("*ptr",
+            std::bind(&STIDecoder::decode_starptr, this, _1, _2));
+    m_dispatcher.register_tag("dsti",
+            std::bind(&STIDecoder::decode_dsti, this, _1, _2));
+    m_dispatcher.register_tag("ss",
+            std::bind(&STIDecoder::decode_ssn, this, _1, _2));
+    m_dispatcher.register_tag("*dmy",
+            std::bind(&STIDecoder::decode_stardmy, this, _1, _2));
+}
+
+void STIDecoder::push_bytes(const vector<uint8_t> &buf)
+{
+    m_dispatcher.push_bytes(buf);
+}
+
+void STIDecoder::push_packet(const vector<uint8_t> &buf)
+{
+    m_dispatcher.push_packet(buf);
+}
+
+void STIDecoder::setMaxDelay(int num_af_packets)
+{
+    m_dispatcher.setMaxDelay(num_af_packets);
+}
+
+#define AFPACKET_HEADER_LEN 10 // includes SYNC
+
+bool STIDecoder::decode_starptr(const vector<uint8_t> &value, uint16_t)
+{
+    if (value.size() != 0x40 / 8) {
+        etiLog.log(warn, "Incorrect length %02lx for *PTR", value.size());
+        return false;
+    }
+
+    char protocol_sz[5];
+    protocol_sz[4] = '\0';
+    copy(value.begin(), value.begin() + 4, protocol_sz);
+    string protocol(protocol_sz);
+
+    uint16_t major = read_16b(value.begin() + 4);
+    uint16_t minor = read_16b(value.begin() + 6);
+
+    m_data_collector.update_protocol(protocol, major, minor);
+
+    return true;
+}
+
+bool STIDecoder::decode_dsti(const vector<uint8_t> &value, uint16_t)
+{
+    size_t offset = 0;
+
+    const uint16_t dstiHeader = read_16b(value.begin() + offset);
+    offset += 2;
+
+    sti_management_data md;
+
+    md.stihf = (dstiHeader >> 15) & 0x1;
+    md.atstf = (dstiHeader >> 14) & 0x1;
+    md.rfadf = (dstiHeader >> 13) & 0x1;
+    uint8_t dfcth = (dstiHeader >> 8) & 0x1F;
+    uint8_t dfctl = dstiHeader & 0xFF;
+
+    md.dflc = dfcth * 250 + dfctl; // modulo 5000 counter
+
+    const size_t expected_length = 2 +
+        (md.stihf ? 3 : 0) +
+        (md.atstf ? 1 + 4 + 3 : 0) +
+        (md.rfadf ? 9 : 0);
+
+    if (value.size() != expected_length) {
+        throw std::logic_error("EDI dsti: Assertion error:"
+                "value.size() != expected_length: " +
+               to_string(value.size()) + " " +
+               to_string(expected_length));
+    }
+
+    if (md.stihf) {
+        const uint8_t stat = value[offset++];
+        const uint16_t spid = read_16b(value.begin() + offset);
+        m_data_collector.update_stat(stat, spid);
+        offset += 2;
+    }
+
+    if (md.atstf) {
+        uint8_t utco = value[offset];
+        offset++;
+
+        uint32_t seconds = read_32b(value.begin() + offset);
+        offset += 4;
+
+        m_data_collector.update_edi_time(utco, seconds);
+
+        md.tsta = read_24b(value.begin() + offset);
+        offset += 3;
+    }
+    else {
+        // Null timestamp, ETSI ETS 300 799, C.2.2
+        md.tsta = 0xFFFFFF;
+    }
+
+
+    if (md.rfadf) {
+        std::array<uint8_t, 9> rfad;
+        copy(value.cbegin() + offset,
+             value.cbegin() + offset + 9,
+             rfad.begin());
+        offset += 9;
+
+        m_data_collector.update_rfad(rfad);
+    }
+
+    m_data_collector.update_sti_management(md);
+
+    return true;
+}
+
+bool STIDecoder::decode_ssn(const vector<uint8_t> &value, uint16_t n)
+{
+    sti_payload_data sti;
+
+    sti.stream_index = n - 1; // n is 1-indexed
+    sti.rfa = value[0] >> 3;
+    sti.tid = value[0] & 0x07;
+
+    uint16_t istc = read_24b(value.begin() + 1);
+    sti.tidext = istc >> 13;
+    sti.crcstf = (istc >> 12) & 0x1;
+    sti.stid = istc & 0xFFF;
+
+    if (sti.rfa != 0) {
+        etiLog.level(warn) << "EDI: rfa field in SSnn tag non-null";
+    }
+
+    copy(   value.cbegin() + 3,
+            value.cend(),
+            back_inserter(sti.istd));
+
+    m_data_collector.add_payload(move(sti));
+
+    return true;
+}
+
+bool STIDecoder::decode_stardmy(const vector<uint8_t>& /*value*/, uint16_t)
+{
+    return true;
+}
+
+void STIDecoder::packet_completed()
+{
+    m_data_collector.assemble();
+}
+
+}
diff --git a/lib/edi/STIDecoder.hpp b/lib/edi/STIDecoder.hpp
new file mode 100644
index 0000000..201a176
--- /dev/null
+++ b/lib/edi/STIDecoder.hpp
@@ -0,0 +1,122 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+#include "common.hpp"
+#include <cstdint>
+#include <deque>
+#include <string>
+#include <vector>
+
+namespace EdiDecoder {
+
+// Information for STI-D Management
+struct sti_management_data {
+    bool stihf;
+    bool atstf;
+    bool rfadf;
+    uint16_t dflc;
+
+    uint32_t tsta;
+};
+
+// Information for a subchannel available in EDI
+struct sti_payload_data {
+    uint16_t stream_index;
+    uint8_t rfa;
+    uint8_t tid;
+    uint8_t tidext;
+    bool crcstf;
+    uint16_t stid;
+    std::vector<uint8_t> istd;
+
+    // Return the length of ISTD in bytes
+    uint16_t stl(void) const { return istd.size(); }
+};
+
+/* A class that receives STI data must implement the interface described
+ * in the STIDataCollector. This can be e.g. a converter to ETI, or something that
+ * prepares data structures for a modulator.
+ */
+class STIDataCollector {
+    public:
+        // Tell the ETIWriter what EDI protocol we receive in *ptr.
+        // This is not part of the ETI data, but is used as check
+        virtual void update_protocol(
+                const std::string& proto,
+                uint16_t major,
+                uint16_t minor) = 0;
+
+        // STAT error field and service provider ID
+        virtual void update_stat(uint8_t stat, uint16_t spid) = 0;
+
+        // In addition to TSTA in ETI, EDI also transports more time
+        // stamp information.
+        virtual void update_edi_time(uint32_t utco, uint32_t seconds) = 0;
+
+        virtual void update_rfad(std::array<uint8_t, 9> rfad) = 0;
+        virtual void update_sti_management(const sti_management_data& data) = 0;
+
+        virtual void add_payload(sti_payload_data&& payload) = 0;
+
+        virtual void assemble() = 0;
+};
+
+/* The STIDecoder takes care of decoding the EDI TAGs related to the transport
+ * of ETI(NI) data inside AF and PF packets.
+ *
+ * PF packets are handed over to the PFT decoder, which will in turn return
+ * AF packets. AF packets are directly handled (TAG extraction) here.
+ */
+class STIDecoder {
+    public:
+        STIDecoder(STIDataCollector& data_collector, bool verbose);
+
+        /* Push bytes into the decoder. The buf can contain more
+         * than a single packet. This is useful when reading from streams
+         * (files, TCP)
+         */
+        void push_bytes(const std::vector<uint8_t> &buf);
+
+        /* Push a complete packet into the decoder. Useful for UDP and other
+         * datagram-oriented protocols.
+         */
+        void push_packet(const std::vector<uint8_t> &buf);
+
+        /* Set the maximum delay in number of AF Packets before we
+         * abandon decoding a given pseq.
+         */
+        void setMaxDelay(int num_af_packets);
+
+    private:
+        bool decode_starptr(const std::vector<uint8_t> &value, uint16_t);
+        bool decode_dsti(const std::vector<uint8_t> &value, uint16_t);
+        bool decode_ssn(const std::vector<uint8_t> &value, uint16_t n);
+        bool decode_stardmy(const std::vector<uint8_t> &value, uint16_t);
+
+        void packet_completed();
+
+        STIDataCollector& m_data_collector;
+        TagDispatcher m_dispatcher;
+
+};
+
+}
diff --git a/lib/edi/STIWriter.cpp b/lib/edi/STIWriter.cpp
new file mode 100644
index 0000000..6964eb1
--- /dev/null
+++ b/lib/edi/STIWriter.cpp
@@ -0,0 +1,138 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include "STIWriter.hpp"
+#include "crc.h"
+#include "Log.h"
+#include <cstdio>
+#include <cassert>
+#include <stdexcept>
+#include <sstream>
+#include <ctime>
+#include <iostream>
+#include <iomanip>
+#include <sstream>
+
+namespace EdiDecoder {
+
+using namespace std;
+
+void STIWriter::update_protocol(
+        const std::string& proto,
+        uint16_t major,
+        uint16_t minor)
+{
+    m_proto_valid = (proto == "DSTI" and major == 0 and minor == 0);
+
+    if (not m_proto_valid) {
+        throw std::invalid_argument("Wrong EDI protocol");
+    }
+}
+
+void STIWriter::reinit()
+{
+    m_proto_valid = false;
+    m_management_data_valid = false;
+    m_stat_valid = false;
+    m_time_valid = false;
+    m_payload_valid = false;
+    m_stiFrame.frame.clear();
+}
+
+void STIWriter::update_stat(uint8_t stat, uint16_t spid)
+{
+    m_stat = stat;
+    m_spid = spid;
+    m_stat_valid = true;
+
+    if (m_stat != 0xFF) {
+        etiLog.log(warn, "STI errorlevel %02x", m_stat);
+    }
+}
+
+void STIWriter::update_rfad(std::array<uint8_t, 9> rfad)
+{
+    (void)rfad;
+}
+
+void STIWriter::update_sti_management(const sti_management_data& data)
+{
+    m_management_data = data;
+    m_management_data_valid = true;
+}
+
+void STIWriter::add_payload(sti_payload_data&& payload)
+{
+    m_payload = move(payload);
+    m_payload_valid = true;
+}
+
+void STIWriter::update_edi_time(
+        uint32_t utco,
+        uint32_t seconds)
+{
+    if (not m_proto_valid) {
+        throw std::logic_error("Cannot update time before protocol");
+    }
+
+    m_utco = utco;
+    m_seconds = seconds;
+
+    // TODO check validity
+    m_time_valid = true;
+}
+
+
+void STIWriter::assemble()
+{
+    if (not m_proto_valid) {
+        throw std::logic_error("Cannot assemble STI before protocol");
+    }
+
+    if (not m_management_data_valid) {
+        throw std::logic_error("Cannot assemble STI before management data");
+    }
+
+    if (not m_payload_valid) {
+        throw std::logic_error("Cannot assemble STI without frame data");
+    }
+
+    // TODO check time validity
+
+    // Do copies so as to preserve existing payload data
+    m_stiFrame.frame = m_payload.istd;
+    m_stiFrame.timestamp.seconds = m_seconds;
+    m_stiFrame.timestamp.utco = m_utco;
+}
+
+sti_frame_t STIWriter::getFrame()
+{
+    if (m_stiFrame.frame.empty()) {
+        return {};
+    }
+
+    sti_frame_t sti;
+    swap(sti, m_stiFrame);
+    reinit();
+    return sti;
+}
+
+}
+
diff --git a/lib/edi/STIWriter.hpp b/lib/edi/STIWriter.hpp
new file mode 100644
index 0000000..a75cb69
--- /dev/null
+++ b/lib/edi/STIWriter.hpp
@@ -0,0 +1,84 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+#include "common.hpp"
+#include "STIDecoder.hpp"
+#include <cstdint>
+#include <string>
+#include <vector>
+#include <list>
+
+namespace EdiDecoder {
+
+struct sti_frame_t {
+    std::vector<uint8_t> frame;
+    frame_timestamp_t timestamp;
+};
+
+class STIWriter : public STIDataCollector {
+    public:
+        // Tell the ETIWriter what EDI protocol we receive in *ptr.
+        // This is not part of the ETI data, but is used as check
+        virtual void update_protocol(
+                const std::string& proto,
+                uint16_t major,
+                uint16_t minor);
+
+        virtual void update_stat(uint8_t stat, uint16_t spid);
+
+        virtual void update_edi_time(
+                uint32_t utco,
+                uint32_t seconds);
+
+        virtual void update_rfad(std::array<uint8_t, 9> rfad);
+        virtual void update_sti_management(const sti_management_data& data);
+        virtual void add_payload(sti_payload_data&& payload);
+
+        virtual void assemble(void);
+
+        // Return the assembled frame or an empty frame if not ready
+        sti_frame_t getFrame();
+
+    private:
+        void reinit(void);
+
+        bool m_proto_valid = false;
+
+        bool m_management_data_valid = false;
+        sti_management_data m_management_data;
+
+        bool m_stat_valid = false;
+        uint8_t m_stat = 0;
+        uint16_t m_spid = 0;
+
+        bool m_time_valid = false;
+        uint32_t m_utco = 0;
+        uint32_t m_seconds = 0;
+
+        bool m_payload_valid = false;
+        sti_payload_data m_payload;
+
+        sti_frame_t m_stiFrame;
+};
+
+}
+
diff --git a/lib/edi/buffer_unpack.hpp b/lib/edi/buffer_unpack.hpp
new file mode 100644
index 0000000..05a1534
--- /dev/null
+++ b/lib/edi/buffer_unpack.hpp
@@ -0,0 +1,62 @@
+/*
+   Copyright (C) 2016
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+#include <stdint.h>
+
+namespace EdiDecoder {
+
+template<class T>
+uint16_t read_16b(T buf)
+{
+    uint16_t value = 0;
+    value = (uint16_t)(buf[0]) << 8;
+    value |= (uint16_t)(buf[1]);
+    return value;
+}
+
+template<class T>
+uint32_t read_24b(T buf)
+{
+    uint32_t value = 0;
+    value = (uint32_t)(buf[0]) << 16;
+    value |= (uint32_t)(buf[1]) << 8;
+    value |= (uint32_t)(buf[2]);
+    return value;
+}
+
+template<class T>
+uint32_t read_32b(T buf)
+{
+    uint32_t value = 0;
+    value = (uint32_t)(buf[0]) << 24;
+    value |= (uint32_t)(buf[1]) << 16;
+    value |= (uint32_t)(buf[2]) << 8;
+    value |= (uint32_t)(buf[3]);
+    return value;
+}
+
+inline uint32_t unpack1bit(uint8_t byte, int bitpos)
+{
+    return (byte & 1 << (7-bitpos)) > (7-bitpos);
+}
+
+}
diff --git a/lib/edi/common.cpp b/lib/edi/common.cpp
new file mode 100644
index 0000000..bc0fa1b
--- /dev/null
+++ b/lib/edi/common.cpp
@@ -0,0 +1,300 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include "common.hpp"
+#include "buffer_unpack.hpp"
+#include "Log.h"
+#include "crc.h"
+#include <iomanip>
+#include <sstream>
+#include <cassert>
+#include <cstdio>
+
+namespace EdiDecoder {
+
+using namespace std;
+
+string frame_timestamp_t::to_string() const
+{
+    const time_t seconds_in_unix_epoch = to_unix_epoch();
+
+    stringstream ss;
+    ss << "Timestamp: " << std::put_time(std::gmtime(&seconds_in_unix_epoch), "%c %Z");
+    return ss.str();
+}
+
+time_t frame_timestamp_t::to_unix_epoch() const
+{
+    // EDI epoch: 2000-01-01T00:00:00Z
+    // Convert using
+    // TZ=UTC python -c 'import datetime; print(datetime.datetime(2000,1,1,0,0,0,0).strftime("%s"))'
+    return 946684800 + seconds - utco;
+}
+
+
+TagDispatcher::TagDispatcher(
+        std::function<void()>&& af_packet_completed, bool verbose) :
+    m_af_packet_completed(move(af_packet_completed))
+{
+    m_pft.setVerbose(verbose);
+}
+
+void TagDispatcher::push_bytes(const vector<uint8_t> &buf)
+{
+    copy(buf.begin(), buf.end(), back_inserter(m_input_data));
+
+    while (m_input_data.size() > 2) {
+        if (m_input_data[0] == 'A' and m_input_data[1] == 'F') {
+            const decode_state_t st = decode_afpacket(m_input_data);
+
+            if (st.num_bytes_consumed == 0 and not st.complete) {
+                // We need to refill our buffer
+                break;
+            }
+
+            if (st.num_bytes_consumed) {
+                vector<uint8_t> remaining_data;
+                copy(m_input_data.begin() + st.num_bytes_consumed,
+                        m_input_data.end(),
+                        back_inserter(remaining_data));
+                m_input_data = remaining_data;
+            }
+
+            if (st.complete) {
+                m_af_packet_completed();
+            }
+        }
+        else if (m_input_data[0] == 'P' and m_input_data[1] == 'F') {
+            PFT::Fragment fragment;
+            const size_t fragment_bytes = fragment.loadData(m_input_data);
+
+            if (fragment_bytes == 0) {
+                // We need to refill our buffer
+                break;
+            }
+
+            vector<uint8_t> remaining_data;
+            copy(m_input_data.begin() + fragment_bytes,
+                    m_input_data.end(),
+                    back_inserter(remaining_data));
+            m_input_data = remaining_data;
+
+            if (fragment.isValid()) {
+                m_pft.pushPFTFrag(fragment);
+            }
+
+            auto af = m_pft.getNextAFPacket();
+            if (not af.empty()) {
+                decode_state_t st = decode_afpacket(af);
+
+                if (st.complete) {
+                    m_af_packet_completed();
+                }
+            }
+        }
+        else {
+            etiLog.log(warn,"Unknown %c!", *m_input_data.data());
+            m_input_data.erase(m_input_data.begin());
+        }
+    }
+}
+
+void TagDispatcher::push_packet(const vector<uint8_t> &buf)
+{
+    if (buf.size() < 2) {
+        throw std::invalid_argument("Not enough bytes to read EDI packet header");
+    }
+
+    if (buf[0] == 'A' and buf[1] == 'F') {
+        const decode_state_t st = decode_afpacket(buf);
+
+        if (st.complete) {
+            m_af_packet_completed();
+        }
+
+    }
+    else if (buf[0] == 'P' and buf[1] == 'F') {
+        PFT::Fragment fragment;
+        fragment.loadData(buf);
+
+        if (fragment.isValid()) {
+            m_pft.pushPFTFrag(fragment);
+        }
+
+        auto af = m_pft.getNextAFPacket();
+        if (not af.empty()) {
+            const decode_state_t st = decode_afpacket(af);
+
+            if (st.complete) {
+                m_af_packet_completed();
+            }
+        }
+    }
+    else {
+        const char packettype[3] = {(char)buf[0], (char)buf[1], '\0'};
+        std::stringstream ss;
+        ss << "Unknown EDI packet ";
+        ss << packettype;
+        throw std::invalid_argument(ss.str());
+    }
+}
+
+void TagDispatcher::setMaxDelay(int num_af_packets)
+{
+    m_pft.setMaxDelay(num_af_packets);
+}
+
+
+#define AFPACKET_HEADER_LEN 10 // includes SYNC
+decode_state_t TagDispatcher::decode_afpacket(
+        const std::vector<uint8_t> &input_data)
+{
+    if (input_data.size() < AFPACKET_HEADER_LEN) {
+        return {false, 0};
+    }
+
+    // read length from packet
+    uint32_t taglength = read_32b(input_data.begin() + 2);
+    uint16_t seq = read_16b(input_data.begin() + 6);
+
+    const size_t crclength = 2;
+    if (input_data.size() < AFPACKET_HEADER_LEN + taglength + crclength) {
+        return {false, 0};
+    }
+
+    if (m_last_seq + 1 != seq) {
+        etiLog.level(warn) << "EDI AF Packet sequence error, " << seq;
+    }
+    m_last_seq = seq;
+
+    bool has_crc = (input_data[8] & 0x80) ? true : false;
+    uint8_t major_revision = (input_data[8] & 0x70) >> 4;
+    uint8_t minor_revision = input_data[8] & 0x0F;
+    if (major_revision != 1 or minor_revision != 0) {
+        throw invalid_argument("EDI AF Packet has wrong revision " +
+                to_string(major_revision) + "." + to_string(minor_revision));
+    }
+    uint8_t pt = input_data[9];
+    if (pt != 'T') {
+        // only support Tag
+        return {false, 0};
+    }
+
+
+    if (not has_crc) {
+        throw invalid_argument("AF packet not supported, has no CRC");
+    }
+
+    uint16_t crc = 0xffff;
+    for (size_t i = 0; i < AFPACKET_HEADER_LEN + taglength; i++) {
+        crc = crc16(crc, &input_data[i], 1);
+    }
+    crc ^= 0xffff;
+
+    uint16_t packet_crc = read_16b(input_data.begin() + AFPACKET_HEADER_LEN + taglength);
+
+    if (packet_crc != crc) {
+        throw invalid_argument(
+                "AF Packet crc wrong");
+    }
+    else {
+        vector<uint8_t> payload(taglength);
+        copy(input_data.begin() + AFPACKET_HEADER_LEN,
+                input_data.begin() + AFPACKET_HEADER_LEN + taglength,
+                payload.begin());
+
+        return {decode_tagpacket(payload),
+            AFPACKET_HEADER_LEN + taglength + 2};
+    }
+}
+
+void TagDispatcher::register_tag(const std::string& tag, tag_handler&& h)
+{
+    m_handlers[tag] = move(h);
+}
+
+
+bool TagDispatcher::decode_tagpacket(const vector<uint8_t> &payload)
+{
+    size_t length = 0;
+
+    bool success = true;
+
+    for (size_t i = 0; i + 8 < payload.size(); i += 8 + length) {
+        char tag_sz[5];
+        tag_sz[4] = '\0';
+        copy(payload.begin() + i, payload.begin() + i + 4, tag_sz);
+
+        string tag(tag_sz);
+
+        uint32_t taglength = read_32b(payload.begin() + i + 4);
+
+        if (taglength % 8 != 0) {
+            etiLog.log(warn, "Invalid tag length!");
+            break;
+        }
+        taglength /= 8;
+
+        length = taglength;
+
+        vector<uint8_t> tag_value(taglength);
+        copy(   payload.begin() + i+8,
+                payload.begin() + i+8+taglength,
+                tag_value.begin());
+
+        bool tagsuccess = false;
+        bool found = false;
+        for (auto tag_handler : m_handlers) {
+            if (tag_handler.first.size() == 4 and tag_handler.first == tag) {
+                found = true;
+                tagsuccess = tag_handler.second(tag_value, 0);
+            }
+            else if (tag_handler.first.size() == 3 and
+                    tag.substr(0, 3) == tag_handler.first) {
+                found = true;
+                uint8_t n = tag_sz[3];
+                tagsuccess = tag_handler.second(tag_value, n);
+            }
+            else if (tag_handler.first.size() == 2 and
+                    tag.substr(0, 2) == tag_handler.first) {
+                found = true;
+                uint16_t n = 0;
+                n = (uint16_t)(tag_sz[2]) << 8;
+                n |= (uint16_t)(tag_sz[3]);
+                tagsuccess = tag_handler.second(tag_value, n);
+            }
+        }
+
+        if (not found) {
+            etiLog.log(warn, "Ignoring unknown TAG %s", tag.c_str());
+            break;
+        }
+
+        if (not tagsuccess) {
+            etiLog.log(warn, "Error decoding TAG %s", tag.c_str());
+            success = tagsuccess;
+            break;
+        }
+    }
+
+    return success;
+}
+
+}
diff --git a/lib/edi/common.hpp b/lib/edi/common.hpp
new file mode 100644
index 0000000..1433004
--- /dev/null
+++ b/lib/edi/common.hpp
@@ -0,0 +1,88 @@
+/*
+   Copyright (C) 2019
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   http://opendigitalradio.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+#include "PFT.hpp"
+#include <functional>
+#include <map>
+#include <string>
+#include <vector>
+#include <cstddef>
+#include <ctime>
+
+namespace EdiDecoder {
+
+struct frame_timestamp_t {
+    uint32_t seconds = 0;
+    uint32_t utco = 0;
+
+    std::string to_string() const;
+    time_t to_unix_epoch() const;
+};
+
+struct decode_state_t {
+    decode_state_t(bool _complete, size_t _num_bytes_consumed) :
+        complete(_complete), num_bytes_consumed(_num_bytes_consumed) {}
+    bool complete;
+    size_t num_bytes_consumed;
+};
+
+/* The TagDispatcher takes care of decoding EDI, with or without PFT, and
+ * will call functions when TAGs are encountered.
+ *
+ * PF packets are handed over to the PFT decoder, which will in turn return
+ * AF packets. AF packets are directly dispatched to the TAG functions.
+ */
+class TagDispatcher {
+    public:
+        TagDispatcher(std::function<void()>&& af_packet_completed, bool verbose);
+
+        /* Push bytes into the decoder. The buf can contain more
+         * than a single packet. This is useful when reading from streams
+         * (files, TCP)
+         */
+        void push_bytes(const std::vector<uint8_t> &buf);
+
+        /* Push a complete packet into the decoder. Useful for UDP and other
+         * datagram-oriented protocols.
+         */
+        void push_packet(const std::vector<uint8_t> &buf);
+
+        /* Set the maximum delay in number of AF Packets before we
+         * abandon decoding a given pseq.
+         */
+        void setMaxDelay(int num_af_packets);
+
+        using tag_handler = std::function<bool(std::vector<uint8_t>, uint16_t)>;
+        void register_tag(const std::string& tag, tag_handler&& h);
+
+    private:
+        decode_state_t decode_afpacket(const std::vector<uint8_t> &input_data);
+        bool decode_tagpacket(const std::vector<uint8_t> &payload);
+
+        PFT::PFT m_pft;
+        uint16_t m_last_seq = 0;
+        std::vector<uint8_t> m_input_data;
+        std::map<std::string, tag_handler> m_handlers;
+        std::function<void()> m_af_packet_completed;
+};
+
+}