1 files changed, 629 insertions, 245 deletions

diff --git a/toxav/rtp.c b/toxav/rtp.c
index 06bc6df5..c5d940e2 100644
--- a/toxav/rtp.c
+++ b/toxav/rtp.c
@@ -33,11 +33,557 @@
 #include <errno.h>
 #include <stdlib.h>
 
+enum {
+    /**
+     * The number of milliseconds we want to keep a keyframe in the buffer for,
+     * even though there are no free slots for incoming frames.
+     */
+    VIDEO_KEEP_KEYFRAME_IN_BUFFER_FOR_MS = 15,
+};
+
+// allocate_len is NOT including header!
+static struct RTPMessage *new_message(const struct RTPHeader *header, size_t allocate_len, const uint8_t *data,
+                                      uint16_t data_length)
+{
+    assert(allocate_len >= data_length);
+    struct RTPMessage *msg = (struct RTPMessage *)calloc(1, sizeof(struct RTPMessage) + allocate_len);
+
+    if (msg == nullptr) {
+        return nullptr;
+    }
+
+    msg->len = data_length; // result without header
+    msg->header = *header;
+    memcpy(msg->data, data, msg->len);
+    return msg;
+}
+
+enum {
+    /**
+     * Instruct the caller to clear slot 0.
+     */
+    GET_SLOT_RESULT_DROP_OLDEST_SLOT = -1,
+    /**
+     * Instruct the caller to drop the incoming packet.
+     */
+    GET_SLOT_RESULT_DROP_INCOMING = -2,
+};
+
+/**
+ * Find the next free slot in work_buffer for the incoming data packet.
+ *
+ * - If the data packet belongs to a frame thats already in the work_buffer then
+ *   use that slot.
+ * - If there is no free slot return GET_SLOT_RESULT_DROP_OLDEST_SLOT.
+ * - If the data packet is too old return GET_SLOT_RESULT_DROP_INCOMING.
+ *
+ * If there is a keyframe beeing assembled in slot 0, keep it a bit longer and
+ * do not kick it out right away if all slots are full instead kick out the new
+ * incoming interframe.
+ */
+static int8_t get_slot(Logger *log, struct RTPWorkBufferList *wkbl, bool is_keyframe,
+                       const struct RTPHeader *header, bool is_multipart)
+{
+    if (is_multipart) {
+        // This RTP message is part of a multipart frame, so we try to find an
+        // existing slot with the previous parts of the frame in it.
+        for (uint8_t i = 0; i < wkbl->next_free_entry; i++) {
+            const struct RTPWorkBuffer *slot = &wkbl->work_buffer[i];
+
+            if ((slot->buf->header.sequnum == header->sequnum) && (slot->buf->header.timestamp == header->timestamp)) {
+                // Sequence number and timestamp match, so this slot belongs to
+                // the same frame.
+                //
+                // In reality, these will almost certainly either both match or
+                // both not match. Only if somehow there were 65535 frames
+                // between, the timestamp will matter.
+                return i;
+            }
+        }
+    }
+
+    // The message may or may not be part of a multipart frame.
+    //
+    // If it is part of a multipart frame, then this is an entirely new frame
+    // for which we did not have a slot *or* the frame is so old that its slot
+    // has been evicted by now.
+    //
+    //        |----------- time ----------->
+    //        _________________
+    // slot 0 |               |
+    //        -----------------
+    //                     _________________
+    // slot 1              |               |
+    //                     -----------------
+    //                ____________
+    // slot 2         |          | -> frame too old, drop
+    //                ------------
+    //
+    //
+    //
+    //        |----------- time ----------->
+    //        _________________
+    // slot 0 |               |
+    //        -----------------
+    //                     _________________
+    // slot 1              |               |
+    //                     -----------------
+    //                              ____________
+    // slot 2                       |          | -> ok, start filling in a new slot
+    //                              ------------
+
+    // If there is a free slot:
+    if (wkbl->next_free_entry < USED_RTP_WORKBUFFER_COUNT) {
+        // If there is at least one filled slot:
+        if (wkbl->next_free_entry > 0) {
+            // Get the most recently filled slot.
+            const struct RTPWorkBuffer *slot = &wkbl->work_buffer[wkbl->next_free_entry - 1];
+
+            // If the incoming packet is older than our newest slot, drop it.
+            // This is the first situation in the above diagram.
+            if (slot->buf->header.timestamp > header->timestamp) {
+                LOGGER_DEBUG(log, "workbuffer:2:timestamp too old");
+                return GET_SLOT_RESULT_DROP_INCOMING;
+            }
+        }
+
+        // Not all slots are filled, and the packet is newer than our most
+        // recent slot, so it's a new frame we want to start assembling. This is
+        // the second situation in the above diagram.
+        return wkbl->next_free_entry;
+    }
+
+    // If the incoming frame is a key frame, then stop assembling the oldest
+    // slot, regardless of whether there was a keyframe in that or not.
+    if (is_keyframe) {
+        return GET_SLOT_RESULT_DROP_OLDEST_SLOT;
+    }
+
+    // The incoming slot is not a key frame, so we look at slot 0 to see what to
+    // do next.
+    const struct RTPWorkBuffer *slot = &wkbl->work_buffer[0];
+
+    // The incoming frame is not a key frame, but the existing slot 0 is also
+    // not a keyframe, so we stop assembling the existing frame and make space
+    // for the new one.
+    if (!slot->is_keyframe) {
+        return GET_SLOT_RESULT_DROP_OLDEST_SLOT;
+    }
+
+    // If this key frame is fully received, we also stop assembling and clear
+    // slot 0.  This also means sending the frame to the decoder.
+    if (slot->received_len == slot->buf->header.data_length_full) {
+        return GET_SLOT_RESULT_DROP_OLDEST_SLOT;
+    }
+
+    // This is a key frame, not fully received yet, but it's already much older
+    // than the incoming frame, so we stop assembling it and send whatever part
+    // we did receive to the decoder.
+    if (slot->buf->header.timestamp + VIDEO_KEEP_KEYFRAME_IN_BUFFER_FOR_MS <= header->timestamp) {
+        return GET_SLOT_RESULT_DROP_OLDEST_SLOT;
+    }
+
+    // This is a key frame, it's not too old yet, so we keep it in its slot for
+    // a little longer.
+    LOGGER_INFO(log, "keep KEYFRAME in workbuffer");
+    return GET_SLOT_RESULT_DROP_INCOMING;
+}
+
+/**
+ * Returns an assembled frame (as much data as we currently have for this frame,
+ * some pieces may be missing)
+ *
+ * If there are no frames ready, we return NULL. If this function returns
+ * non-NULL, it transfers ownership of the message to the caller, i.e. the
+ * caller is responsible for storing it elsewhere or calling free().
+ */
+static struct RTPMessage *process_frame(Logger *log, struct RTPWorkBufferList *wkbl, uint8_t slot_id)
+{
+    assert(wkbl->next_free_entry >= 0);
+
+    if (wkbl->next_free_entry == 0) {
+        // There are no frames in any slot.
+        return nullptr;
+    }
+
+    // Slot 0 contains a key frame, slot_id points at an interframe that is
+    // relative to that key frame, so we don't use it yet.
+    if (wkbl->work_buffer[0].is_keyframe && slot_id != 0) {
+        LOGGER_DEBUG(log, "process_frame:KEYFRAME waiting in slot 0");
+        return nullptr;
+    }
+
+    // Either slot_id is 0 and slot 0 is a key frame, or there is no key frame
+    // in slot 0 (and slot_id is anything).
+    struct RTPWorkBuffer *const slot = &wkbl->work_buffer[slot_id];
+
+    // Move ownership of the frame out of the slot into m_new.
+    struct RTPMessage *const m_new = slot->buf;
+    slot->buf = nullptr;
+
+    assert(wkbl->next_free_entry >= 1);
+
+    if (slot_id != wkbl->next_free_entry - 1) {
+        // The slot is not the last slot, so we created a gap. We move all the
+        // entries after it one step up.
+        for (uint8_t i = slot_id; i < wkbl->next_free_entry - 1; i++) {
+            // Move entry (i+1) into entry (i).
+            wkbl->work_buffer[i] = wkbl->work_buffer[i + 1];
+        }
+    }
+
+    // We now have a free entry at the end of the array.
+    wkbl->next_free_entry--;
+
+    // Clear the newly freed entry.
+    const struct RTPWorkBuffer empty = {0};
+    wkbl->work_buffer[wkbl->next_free_entry] = empty;
+
+    // Move ownership of the frame to the caller.
+    return m_new;
+}
+
+/**
+ * @param log A logger.
+ * @param wkbl The list of in-progress frames, i.e. all the slots.
+ * @param slot_id The slot we want to fill the data into.
+ * @param is_keyframe Whether the data is part of a key frame.
+ * @param header The RTP header from the incoming packet.
+ * @param incoming_data The pure payload without header.
+ * @param incoming_data_length The length in bytes of the incoming data payload.
+ */
+static bool fill_data_into_slot(Logger *log, struct RTPWorkBufferList *wkbl, const uint8_t slot_id, bool is_keyframe,
+                                const struct RTPHeader *header, const uint8_t *incoming_data, uint16_t incoming_data_length)
+{
+    // We're either filling the data into an existing slot, or in a new one that
+    // is the next free entry.
+    assert(slot_id <= wkbl->next_free_entry);
+    struct RTPWorkBuffer *const slot = &wkbl->work_buffer[slot_id];
+
+    assert(header != nullptr);
+    assert(is_keyframe == (bool)(header->flags & RTP_KEY_FRAME));
+
+    if (slot->received_len == 0) {
+        assert(slot->buf == nullptr);
+
+        // No data for this slot has been received, yet, so we create a new
+        // message for it with enough memory for the entire frame.
+        struct RTPMessage *msg = (struct RTPMessage *)calloc(1, sizeof(struct RTPMessage) + header->data_length_full);
+
+        if (msg == nullptr) {
+            LOGGER_ERROR(log, "Out of memory while trying to allocate for frame of size %u\n",
+                         (unsigned)header->data_length_full);
+            // Out of memory: throw away the incoming data.
+            return false;
+        }
+
+        // Unused in the new video receiving code, as it's 16 bit and can't hold
+        // the full length of large frames. Instead, we use slot->received_len.
+        msg->len = 0;
+        msg->header = *header;
+
+        slot->buf = msg;
+        slot->is_keyframe = is_keyframe;
+        slot->received_len = 0;
+
+        assert(wkbl->next_free_entry < USED_RTP_WORKBUFFER_COUNT);
+        wkbl->next_free_entry++;
+    }
+
+    // We already checked this when we received the packet, but we rely on it
+    // here, so assert again.
+    assert(header->offset_full < header->data_length_full);
+
+    // Copy the incoming chunk of data into the correct position in the full
+    // frame data array.
+    memcpy(
+        slot->buf->data + header->offset_full,
+        incoming_data,
+        incoming_data_length
+    );
+
+    // Update the total received length of this slot.
+    slot->received_len += incoming_data_length;
+
+    // Update received length also in the header of the message, for later use.
+    slot->buf->header.received_length_full = slot->received_len;
+
+    return slot->received_len == header->data_length_full;
+}
+
+static void update_bwc_values(Logger *log, RTPSession *session, const struct RTPMessage *msg)
+{
+    if (session->first_packets_counter < DISMISS_FIRST_LOST_VIDEO_PACKET_COUNT) {
+        session->first_packets_counter++;
+    } else {
+        uint32_t data_length_full = msg->header.data_length_full; // without header
+        uint32_t received_length_full = msg->header.received_length_full; // without header
+        bwc_add_recv(session->bwc, data_length_full);
+
+        if (received_length_full < data_length_full) {
+            LOGGER_DEBUG(log, "BWC: full length=%u received length=%d", data_length_full, received_length_full);
+            bwc_add_lost(session->bwc, (data_length_full - received_length_full));
+        }
+    }
+}
+
+/**
+ * Handle a single RTP video packet.
+ *
+ * The packet may or may not be part of a multipart frame. This function will
+ * find out and handle it appropriately.
+ *
+ * @param session The current RTP session with:
+ *   session->mcb == vc_queue_message() // this function is called from here
+ *   session->mp == struct RTPMessage *
+ *   session->cs == call->video.second // == VCSession created by vc_new() call
+ * @param header The RTP header deserialised from the packet.
+ * @param incoming_data The packet data *not* header, i.e. this is the actual
+ *   payload.
+ * @param incoming_data_length The packet length *not* including header, i.e.
+ *   this is the actual payload length.
+ * @param log A logger.
+ *
+ * @return -1 on error, 0 on success.
+ */
+static int handle_video_packet(RTPSession *session, const struct RTPHeader *header,
+                               const uint8_t *incoming_data, uint16_t incoming_data_length, Logger *log)
+{
+    // Full frame length in bytes. The frame may be split into multiple packets,
+    // but this value is the complete assembled frame size.
+    const uint32_t full_frame_length = header->data_length_full;
+
+    // Current offset in the frame. If this is the first packet of a multipart
+    // frame or it's not a multipart frame, then this value is 0.
+    const uint32_t offset = header->offset_full; // without header
+
+    // The sender tells us whether this is a key frame.
+    const bool is_keyframe = (header->flags & RTP_KEY_FRAME) != 0;
+
+    LOGGER_DEBUG(log, "-- handle_video_packet -- full lens=%u len=%u offset=%u is_keyframe=%s",
+                 (unsigned)incoming_data_length, (unsigned)full_frame_length, (unsigned)offset, is_keyframe ? "K" : ".");
+    LOGGER_DEBUG(log, "wkbl->next_free_entry:003=%d", session->work_buffer_list->next_free_entry);
+
+    const bool is_multipart = full_frame_length != incoming_data_length;
+
+    /* The message was sent in single part */
+    int8_t slot_id = get_slot(log, session->work_buffer_list, is_keyframe, header, is_multipart);
+    LOGGER_DEBUG(log, "slot num=%d", slot_id);
+
+    // get_slot told us to drop the packet, so we ignore it.
+    if (slot_id == GET_SLOT_RESULT_DROP_INCOMING) {
+        return -1;
+    }
+
+    // get_slot said there is no free slot.
+    if (slot_id == GET_SLOT_RESULT_DROP_OLDEST_SLOT) {
+        LOGGER_DEBUG(log, "there was no free slot, so we process the oldest frame");
+        // We now own the frame.
+        struct RTPMessage *m_new = process_frame(log, session->work_buffer_list, 0);
+
+        // The process_frame function returns NULL if there is no slot 0, i.e.
+        // the work buffer list is completely empty. It can't be empty, because
+        // get_slot just told us it's full, so process_frame must return non-null.
+        assert(m_new != nullptr);
+
+        LOGGER_DEBUG(log, "-- handle_video_packet -- CALLBACK-001a b0=%d b1=%d", (int)m_new->data[0], (int)m_new->data[1]);
+        update_bwc_values(log, session, m_new);
+        // Pass ownership of m_new to the callback.
+        session->mcb(session->cs, m_new);
+        // Now we no longer own m_new.
+        m_new = nullptr;
+
+        // Now we must have a free slot, so we either get that slot, i.e. >= 0,
+        // or get told to drop the incoming packet if it's too old.
+        slot_id = get_slot(log, session->work_buffer_list, is_keyframe, header, /* is_multipart */false);
+
+        if (slot_id == GET_SLOT_RESULT_DROP_INCOMING) {
+            // The incoming frame is too old, so we drop it.
+            return -1;
+        }
+    }
+
+    // We must have a valid slot here.
+    assert(slot_id >= 0);
+
+    LOGGER_DEBUG(log, "fill_data_into_slot.1");
+
+    // fill in this part into the slot buffer at the correct offset
+    if (!fill_data_into_slot(
+                log,
+                session->work_buffer_list,
+                slot_id,
+                is_keyframe,
+                header,
+                incoming_data,
+                incoming_data_length)) {
+        // Memory allocation failed. Return error.
+        return -1;
+    }
+
+    struct RTPMessage *m_new = process_frame(log, session->work_buffer_list, slot_id);
+
+    if (m_new) {
+        LOGGER_DEBUG(log, "-- handle_video_packet -- CALLBACK-003a b0=%d b1=%d", (int)m_new->data[0], (int)m_new->data[1]);
+        update_bwc_values(log, session, m_new);
+        session->mcb(session->cs, m_new);
+
+        m_new = nullptr;
+    }
+
+    return 0;
+}
+
+/**
+ * @return -1 on error, 0 on success.
+ */
+static int handle_rtp_packet(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint16_t length, void *object)
+{
+    RTPSession *session = (RTPSession *)object;
+
+    if (!session || length < RTP_HEADER_SIZE + 1) {
+        LOGGER_WARNING(m->log, "No session or invalid length of received buffer!");
+        return -1;
+    }
+
+    // Get the packet type.
+    const uint8_t packet_type = data[0];
+    ++data;
+    --length;
+
+    // Unpack the header.
+    struct RTPHeader header;
+    rtp_header_unpack(data, &header);
+
+    if (header.pt != packet_type % 128) {
+        LOGGER_WARNING(m->log, "RTPHeader packet type and Tox protocol packet type did not agree: %d != %d",
+                       header.pt, packet_type % 128);
+        return -1;
+    }
+
+    if (header.pt != session->payload_type % 128) {
+        LOGGER_WARNING(m->log, "RTPHeader packet type does not match this session's payload type: %d != %d",
+                       header.pt, session->payload_type % 128);
+        return -1;
+    }
+
+    if (header.offset_full >= header.data_length_full) {
+        LOGGER_ERROR(m->log, "Invalid video packet: frame offset (%u) >= full frame length (%u)",
+                     (unsigned)header.offset_full, (unsigned)header.data_length_full);
+        return -1;
+    }
+
+    if (header.offset_lower >= header.data_length_lower) {
+        LOGGER_ERROR(m->log, "Invalid old protocol video packet: frame offset (%u) >= full frame length (%u)",
+                     (unsigned)header.offset_lower, (unsigned)header.data_length_lower);
+        return -1;
+    }
+
+    LOGGER_DEBUG(m->log, "header.pt %d, video %d", (uint8_t)header.pt, (rtp_TypeVideo % 128));
+
+    // The sender uses the new large-frame capable protocol and is sending a
+    // video packet.
+    if ((header.flags & RTP_LARGE_FRAME) && header.pt == (rtp_TypeVideo % 128)) {
+        return handle_video_packet(session, &header, data + RTP_HEADER_SIZE, length - RTP_HEADER_SIZE, m->log);
+    }
+
+    // everything below here is for the old 16 bit protocol ------------------
+
+    if (header.data_length_lower == length - RTP_HEADER_SIZE) {
+        /* The message is sent in single part */
+
+        /* Message is not late; pick up the latest parameters */
+        session->rsequnum = header.sequnum;
+        session->rtimestamp = header.timestamp;
+        bwc_add_recv(session->bwc, length);
+
+        /* Invoke processing of active multiparted message */
+        if (session->mp) {
+            session->mcb(session->cs, session->mp);
+            session->mp = nullptr;
+        }
+
+        /* The message came in the allowed time;
+         */
+
+        return session->mcb(session->cs, new_message(&header, length - RTP_HEADER_SIZE, data + RTP_HEADER_SIZE,
+                            length - RTP_HEADER_SIZE));
+    }
+
+    /* The message is sent in multiple parts */
+
+    if (session->mp) {
+        /* There are 2 possible situations in this case:
+         *      1) being that we got the part of already processing message.
+         *      2) being that we got the part of a new/old message.
+         *
+         * We handle them differently as we only allow a single multiparted
+         * processing message
+         */
+        if (session->mp->header.sequnum == header.sequnum &&
+                session->mp->header.timestamp == header.timestamp) {
+            /* First case */
+
+            /* Make sure we have enough allocated memory */
+            if (session->mp->header.data_length_lower - session->mp->len < length - RTP_HEADER_SIZE ||
+                    session->mp->header.data_length_lower <= header.offset_lower) {
+                /* There happened to be some corruption on the stream;
+                 * continue wihtout this part
+                 */
+                return 0;
+            }
+
+            memcpy(session->mp->data + header.offset_lower, data + RTP_HEADER_SIZE,
+                   length - RTP_HEADER_SIZE);
+            session->mp->len += length - RTP_HEADER_SIZE;
+            bwc_add_recv(session->bwc, length);
+
+            if (session->mp->len == session->mp->header.data_length_lower) {
+                /* Received a full message; now push it for the further
+                 * processing.
+                 */
+                session->mcb(session->cs, session->mp);
+                session->mp = nullptr;
+            }
+        } else {
+            /* Second case */
+            if (session->mp->header.timestamp > header.timestamp) {
+                /* The received message part is from the old message;
+                 * discard it.
+                 */
+                return 0;
+            }
+
+            /* Push the previous message for processing */
+            session->mcb(session->cs, session->mp);
+
+            session->mp = nullptr;
+            goto NEW_MULTIPARTED;
+        }
+    } else {
+        /* In this case threat the message as if it was received in order
+         */
+        /* This is also a point for new multiparted messages */
+NEW_MULTIPARTED:
+
+        /* Message is not late; pick up the latest parameters */
+        session->rsequnum = header.sequnum;
+        session->rtimestamp = header.timestamp;
+        bwc_add_recv(session->bwc, length);
+
+        /* Store message.
+         */
+        session->mp = new_message(&header, header.data_length_lower, data + RTP_HEADER_SIZE, length - RTP_HEADER_SIZE);
+        memmove(session->mp->data + header.offset_lower, session->mp->data, session->mp->len);
+    }
+
+    return 0;
+}
 
 size_t rtp_header_pack(uint8_t *const rdata, const struct RTPHeader *header)
 {
     uint8_t *p = rdata;
-    *p++ = (header->protocol_version & 3) << 6
+    *p++ = (header->ve & 3) << 6
            | (header->pe & 1) << 5
            | (header->xe & 1) << 4
            | (header->cc & 0xf);
@@ -62,11 +608,10 @@ size_t rtp_header_pack(uint8_t *const rdata, const struct RTPHeader *header)
     return p - rdata;
 }
 
-
 size_t rtp_header_unpack(const uint8_t *data, struct RTPHeader *header)
 {
     const uint8_t *p = data;
-    header->protocol_version = (*p >> 6) & 3;
+    header->ve = (*p >> 6) & 3;
     header->pe = (*p >> 5) & 1;
     header->xe = (*p >> 4) & 1;
     header->cc = *p & 0xf;
@@ -93,44 +638,56 @@ size_t rtp_header_unpack(const uint8_t *data, struct RTPHeader *header)
 }
 
 
-int handle_rtp_packet(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint16_t length, void *object);
-
-
 RTPSession *rtp_new(int payload_type, Messenger *m, uint32_t friendnumber,
                     BWController *bwc, void *cs,
                     int (*mcb)(void *, struct RTPMessage *))
 {
-    assert(mcb);
-    assert(cs);
-    assert(m);
+    assert(mcb != nullptr);
+    assert(cs != nullptr);
+    assert(m != nullptr);
 
-    RTPSession *retu = (RTPSession *)calloc(1, sizeof(RTPSession));
+    RTPSession *session = (RTPSession *)calloc(1, sizeof(RTPSession));
 
-    if (!retu) {
+    if (!session) {
         LOGGER_WARNING(m->log, "Alloc failed! Program might misbehave!");
         return nullptr;
     }
 
-    retu->ssrc = random_u32();
-    retu->payload_type = payload_type;
+    session->work_buffer_list = (struct RTPWorkBufferList *)calloc(1, sizeof(struct RTPWorkBufferList));
 
-    retu->m = m;
-    retu->friend_number = friendnumber;
+    if (session->work_buffer_list == nullptr) {
+        LOGGER_ERROR(m->log, "out of memory while allocating work buffer list");
+        free(session);
+        return nullptr;
+    }
 
-    /* Also set payload type as prefix */
+    // First entry is free.
+    session->work_buffer_list->next_free_entry = 0;
+
+    session->ssrc = payload_type == rtp_TypeVideo ? 0 : random_u32();
+    session->payload_type = payload_type;
+    session->m = m;
+    session->friend_number = friendnumber;
 
-    retu->bwc = bwc;
-    retu->cs = cs;
-    retu->mcb = mcb;
+    // set NULL just in case
+    session->mp = nullptr;
+    session->first_packets_counter = 1;
 
-    if (-1 == rtp_allow_receiving(retu)) {
+    /* Also set payload type as prefix */
+    session->bwc = bwc;
+    session->cs = cs;
+    session->mcb = mcb;
+
+    if (-1 == rtp_allow_receiving(session)) {
         LOGGER_WARNING(m->log, "Failed to start rtp receiving mode");
-        free(retu);
+        free(session->work_buffer_list);
+        free(session);
         return nullptr;
     }
 
-    return retu;
+    return session;
 }
+
 void rtp_kill(RTPSession *session)
 {
     if (!session) {
@@ -138,10 +695,15 @@ void rtp_kill(RTPSession *session)
     }
 
     LOGGER_DEBUG(session->m->log, "Terminated RTP session: %p", session);
-
     rtp_stop_receiving(session);
+
+    LOGGER_DEBUG(session->m->log, "Terminated RTP session V3 work_buffer_list->next_free_entry: %d",
+                 (int)session->work_buffer_list->next_free_entry);
+
+    free(session->work_buffer_list);
     free(session);
 }
+
 int rtp_allow_receiving(RTPSession *session)
 {
     if (session == nullptr) {
@@ -157,6 +719,7 @@ int rtp_allow_receiving(RTPSession *session)
     LOGGER_DEBUG(session->m->log, "Started receiving on session: %p", session);
     return 0;
 }
+
 int rtp_stop_receiving(RTPSession *session)
 {
     if (session == nullptr) {
@@ -168,42 +731,76 @@ int rtp_stop_receiving(RTPSession *session)
     LOGGER_DEBUG(session->m->log, "Stopped receiving on session: %p", session);
     return 0;
 }
-int rtp_send_data(RTPSession *session, const uint8_t *data, uint16_t length, Logger *log)
+
+/**
+ * @param input is raw vpx data.
+ * @param length is the length of the raw data.
+ */
+int rtp_send_data(RTPSession *session, const uint8_t *data, uint32_t length,
+                  bool is_keyframe, Logger *log)
 {
     if (!session) {
         LOGGER_ERROR(log, "No session!");
         return -1;
     }
 
-    VLA(uint8_t, rdata, length + RTP_HEADER_SIZE + 1);
-    memset(rdata, 0, SIZEOF_VLA(rdata));
+    uint8_t is_video_payload = 0;
 
-    rdata[0] = session->payload_type;
+    if (session->payload_type == rtp_TypeVideo) {
+        is_video_payload = 1;
+    }
 
     struct RTPHeader header = {0};
 
-    header.protocol_version = 2;
+    header.ve = 2;  // this is unused in toxav
+
     header.pe = 0;
+
     header.xe = 0;
+
     header.cc = 0;
 
     header.ma = 0;
+
     header.pt = session->payload_type % 128;
 
     header.sequnum = session->sequnum;
+
     header.timestamp = current_time_monotonic();
+
     header.ssrc = session->ssrc;
 
     header.offset_lower = 0;
+
+    // here the highest bits gets stripped anyway, no need to do keyframe bit magic here!
     header.data_length_lower = length;
 
-    if (MAX_CRYPTO_DATA_SIZE > length + RTP_HEADER_SIZE + 1) {
+    header.flags = RTP_LARGE_FRAME;
 
+    uint16_t length_safe = (uint16_t)length;
+
+    if (length > UINT16_MAX) {
+        length_safe = UINT16_MAX;
+    }
+
+    header.data_length_lower = length_safe;
+    header.data_length_full = length; // without header
+    header.offset_lower = 0;
+    header.offset_full = 0;
+
+    if (is_keyframe) {
+        header.flags |= RTP_KEY_FRAME;
+    }
+
+    VLA(uint8_t, rdata, length + RTP_HEADER_SIZE + 1);
+    memset(rdata, 0, SIZEOF_VLA(rdata));
+    rdata[0] = session->payload_type;  // packet id == payload_type
+
+    if (MAX_CRYPTO_DATA_SIZE > (length + RTP_HEADER_SIZE + 1)) {
         /**
          * The length is lesser than the maximum allowed length (including header)
          * Send the packet in single piece.
          */
-
         rtp_header_pack(rdata + 1, &header);
         memcpy(rdata + 1 + RTP_HEADER_SIZE, data, length);
 
@@ -211,13 +808,11 @@ int rtp_send_data(RTPSession *session, const uint8_t *data, uint16_t length, Log
             LOGGER_WARNING(session->m->log, "RTP send failed (len: %d)! std error: %s", SIZEOF_VLA(rdata), strerror(errno));
         }
     } else {
-
         /**
          * The length is greater than the maximum allowed length (including header)
          * Send the packet in multiple pieces.
          */
-
-        uint16_t sent = 0;
+        uint32_t sent = 0;
         uint16_t piece = MAX_CRYPTO_DATA_SIZE - (RTP_HEADER_SIZE + 1);
 
         while ((length - sent) + RTP_HEADER_SIZE + 1 > MAX_CRYPTO_DATA_SIZE) {
@@ -232,6 +827,7 @@ int rtp_send_data(RTPSession *session, const uint8_t *data, uint16_t length, Log
 
             sent += piece;
             header.offset_lower = sent;
+            header.offset_full = sent; // raw data offset, without any header
         }
 
         /* Send remaining */
@@ -252,215 +848,3 @@ int rtp_send_data(RTPSession *session, const uint8_t *data, uint16_t length, Log
     session->sequnum ++;
     return 0;
 }
-
-
-static bool chloss(const RTPSession *session, const struct RTPHeader *header)
-{
-    if (header->timestamp < session->rtimestamp) {
-        uint16_t hosq, lost = 0;
-
-        hosq = header->sequnum;
-
-        lost = (hosq > session->rsequnum) ?
-               (session->rsequnum + 65535) - hosq :
-               session->rsequnum - hosq;
-
-        fprintf(stderr, "Lost packet\n");
-
-        while (lost --) {
-            bwc_add_lost(session->bwc, 0);
-        }
-
-        return true;
-    }
-
-    return false;
-}
-static struct RTPMessage *new_message(size_t allocate_len, const uint8_t *data, uint16_t data_length)
-{
-    assert(allocate_len >= data_length);
-
-    struct RTPMessage *msg = (struct RTPMessage *)calloc(sizeof(struct RTPMessage) +
-                             (allocate_len - RTP_HEADER_SIZE), 1);
-
-    if (msg == nullptr) {
-        return nullptr;
-    }
-
-    msg->len = data_length - RTP_HEADER_SIZE;
-    rtp_header_unpack(data, &msg->header);
-    memcpy(msg->data, data + RTP_HEADER_SIZE, allocate_len - RTP_HEADER_SIZE);
-
-    return msg;
-}
-
-int handle_rtp_packet(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint16_t length, void *object)
-{
-    (void) m;
-    (void) friendnumber;
-
-    RTPSession *session = (RTPSession *)object;
-
-    data ++;
-    length--;
-
-    if (!session || length < RTP_HEADER_SIZE) {
-        LOGGER_WARNING(m->log, "No session or invalid length of received buffer!");
-        return -1;
-    }
-
-    struct RTPHeader header;
-
-    rtp_header_unpack(data, &header);
-
-    if (header.pt != session->payload_type % 128) {
-        LOGGER_WARNING(m->log, "Invalid payload type with the session");
-        return -1;
-    }
-
-    if (header.offset_lower >= header.data_length_lower) {
-        /* Never allow this case to happen */
-        return -1;
-    }
-
-    bwc_feed_avg(session->bwc, length);
-
-    if (header.data_length_lower == length - RTP_HEADER_SIZE) {
-        /* The message is sent in single part */
-
-        /* Only allow messages which have arrived in order;
-         * drop late messages
-         */
-        if (chloss(session, &header)) {
-            return 0;
-        }
-
-        /* Message is not late; pick up the latest parameters */
-        session->rsequnum = header.sequnum;
-        session->rtimestamp = header.timestamp;
-
-        bwc_add_recv(session->bwc, length);
-
-        /* Invoke processing of active multiparted message */
-        if (session->mp) {
-            if (session->mcb) {
-                session->mcb(session->cs, session->mp);
-            } else {
-                free(session->mp);
-            }
-
-            session->mp = nullptr;
-        }
-
-        /* The message came in the allowed time;
-         * process it only if handler for the session is present.
-         */
-
-        if (!session->mcb) {
-            return 0;
-        }
-
-        return session->mcb(session->cs, new_message(length, data, length));
-    }
-
-    /* The message is sent in multiple parts */
-
-    if (session->mp) {
-        /* There are 2 possible situations in this case:
-         *      1) being that we got the part of already processing message.
-         *      2) being that we got the part of a new/old message.
-         *
-         * We handle them differently as we only allow a single multiparted
-         * processing message
-         */
-
-        if (session->mp->header.sequnum == header.sequnum &&
-                session->mp->header.timestamp == header.timestamp) {
-            /* First case */
-
-            /* Make sure we have enough allocated memory */
-            if (session->mp->header.data_length_lower - session->mp->len < length - RTP_HEADER_SIZE ||
-                    session->mp->header.data_length_lower <= header.offset_lower) {
-                /* There happened to be some corruption on the stream;
-                 * continue wihtout this part
-                 */
-                return 0;
-            }
-
-            memcpy(session->mp->data + header.offset_lower, data + RTP_HEADER_SIZE,
-                   length - RTP_HEADER_SIZE);
-
-            session->mp->len += length - RTP_HEADER_SIZE;
-
-            bwc_add_recv(session->bwc, length);
-
-            if (session->mp->len == session->mp->header.data_length_lower) {
-                /* Received a full message; now push it for the further
-                 * processing.
-                 */
-                if (session->mcb) {
-                    session->mcb(session->cs, session->mp);
-                } else {
-                    free(session->mp);
-                }
-
-                session->mp = nullptr;
-            }
-        } else {
-            /* Second case */
-
-            if (session->mp->header.timestamp > header.timestamp) {
-                /* The received message part is from the old message;
-                 * discard it.
-                 */
-                return 0;
-            }
-
-            /* Measure missing parts of the old message */
-            bwc_add_lost(session->bwc,
-                         (session->mp->header.data_length_lower - session->mp->len) +
-
-                         /* Must account sizes of rtp headers too */
-                         ((session->mp->header.data_length_lower - session->mp->len) /
-                          MAX_CRYPTO_DATA_SIZE) * RTP_HEADER_SIZE);
-
-            /* Push the previous message for processing */
-            if (session->mcb) {
-                session->mcb(session->cs, session->mp);
-            } else {
-                free(session->mp);
-            }
-
-            session->mp = nullptr;
-            goto NEW_MULTIPARTED;
-        }
-    } else {
-        /* In this case threat the message as if it was received in order
-         */
-
-        /* This is also a point for new multiparted messages */
-NEW_MULTIPARTED:
-
-        /* Only allow messages which have arrived in order;
-         * drop late messages
-         */
-        if (chloss(session, &header)) {
-            return 0;
-        }
-
-        /* Message is not late; pick up the latest parameters */
-        session->rsequnum = header.sequnum;
-        session->rtimestamp = header.timestamp;
-
-        bwc_add_recv(session->bwc, length);
-
-        /* Again, only store message if handler is present
-         */
-        if (session->mcb) {
-            session->mp = new_message(header.data_length_lower + RTP_HEADER_SIZE, data, length);
-            memmove(session->mp->data + header.offset_lower, session->mp->data, session->mp->len);
-        }
-    }
-
-    return 0;
-}