Put receiver dropped packets into ring buffer

src/internal_modules/roc_pipeline/config.cpp

@@ -45,16 +45,21 @@ void ReceiverCommonConfig::deduce_defaults() {
 
 ReceiverSessionConfig::ReceiverSessionConfig()
     : payload_type(0)
+    , prebuf_len(0)
     , enable_beeping(false) {
 }
 
 void ReceiverSessionConfig::deduce_defaults() {
+    if (prebuf_len == 0) {
+        prebuf_len = latency.target_latency;
+    }
     latency.deduce_defaults(DefaultLatency, true);
     watchdog.deduce_defaults(latency.target_latency);
     resampler.deduce_defaults(latency.tuner_backend, latency.tuner_profile);
 }
 
-ReceiverSourceConfig::ReceiverSourceConfig() {
+ReceiverSourceConfig::ReceiverSourceConfig()
+    : max_session_packets(0) {
 }
 
 void ReceiverSourceConfig::deduce_defaults() {

src/internal_modules/roc_pipeline/config.h

@@ -152,6 +152,9 @@ struct ReceiverSessionConfig {
     //! Packet payload type.
     unsigned int payload_type;
 
+    //! Packet prebuffer length, nanoseconds.
+    core::nanoseconds_t prebuf_len;
+
     //! FEC reader parameters.
     fec::BlockReaderConfig fec_reader;
 
@@ -188,6 +191,9 @@ struct ReceiverSourceConfig {
     //! Default parameters for a session.
     ReceiverSessionConfig session_defaults;
 
+    //! Maximum number of packets per session.
+    size_t max_session_packets;
+
     //! Initialize config.
     ReceiverSourceConfig();
 

src/internal_modules/roc_pipeline/receiver_session_group.cpp

@@ -328,6 +328,7 @@ ReceiverSessionGroup::route_transport_packet_(const packet::PacketPtr& packet) {
     }
 
     if (sess) {
+        enqueue_prebuf_packet_(packet);
         // Session found, route packet to it.
         return sess->route_packet(packet);
     }
@@ -340,6 +341,48 @@ ReceiverSessionGroup::route_transport_packet_(const packet::PacketPtr& packet) {
     return status::StatusNoRoute;
 }
 
+void ReceiverSessionGroup::enqueue_prebuf_packet_(const packet::PacketPtr& packet_ptr) {
+    prebuf_packets_.push_back(*packet_ptr.get());
+
+    core::nanoseconds_t now = core::timestamp(core::ClockMonotonic);
+
+    while (prebuf_packets_.size() > 0) {
+        core::nanoseconds_t received = prebuf_packets_.front()->udp()->receive_timestamp;
+        if (now - received > source_config_.session_defaults.prebuf_len) {
+            prebuf_packets_.remove(*prebuf_packets_.front());
+        } else {
+            break;
+        }
+    }
+}
+
+void ReceiverSessionGroup::dequeue_prebuf_packets_(ReceiverSession& sess) {
+    packet::PacketPtr curr, next;
+
+    if (prebuf_packets_.size() == 0) {
+        return;
+    }
+
+    core::nanoseconds_t now = core::timestamp(core::ClockMonotonic);
+
+    for (curr = prebuf_packets_.front(); curr; curr = next) {
+        next = prebuf_packets_.nextof(*curr);
+
+        // if packet is too old, remove it from the queue
+        core::nanoseconds_t received = curr->udp()->receive_timestamp;
+        if (now - received > source_config_.session_defaults.prebuf_len) {
+            prebuf_packets_.remove(*curr);
+            continue;
+        }
+
+        // if session handles the packet, remove it from the queue
+        const status::StatusCode code = sess.route_packet(curr);
+        if (code == status::StatusOK) {
+            prebuf_packets_.remove(*curr);
+        }
+    }
+}
+
 status::StatusCode
 ReceiverSessionGroup::route_control_packet_(const packet::PacketPtr& packet,
                                             core::nanoseconds_t current_time) {
@@ -431,6 +474,8 @@ ReceiverSessionGroup::create_session_(const packet::PacketPtr& packet) {
     sessions_.push_back(*sess);
     state_tracker_.register_session();
 
+    dequeue_prebuf_packets_(*sess);
+
     return status::StatusOK;
 }
 

src/internal_modules/roc_pipeline/receiver_session_group.h

@@ -128,6 +128,8 @@ class ReceiverSessionGroup : public core::NonCopyable<>, private rtcp::IParticip
     status::StatusCode route_transport_packet_(const packet::PacketPtr& packet);
     status::StatusCode route_control_packet_(const packet::PacketPtr& packet,
                                              core::nanoseconds_t current_time);
+    void enqueue_prebuf_packet_(const packet::PacketPtr& packet);
+    void dequeue_prebuf_packets_(ReceiverSession& sess);
 
     bool can_create_session_(const packet::PacketPtr& packet);
 
@@ -159,6 +161,8 @@ class ReceiverSessionGroup : public core::NonCopyable<>, private rtcp::IParticip
             sessions_;
     ReceiverSessionRouter session_router_;
 
+    core::List<packet::Packet> prebuf_packets_;
+
     status::StatusCode init_status_;
 };
 

src/public_api/include/roc/config.h

@@ -910,6 +910,14 @@ typedef struct roc_receiver_config {
      * If zero, default value is used. If negative, the check is disabled.
      */
     long long choppy_playback_timeout;
+
+    /** Packet prebuffer length, in nanoseconds.
+     * Packets received for sessions that have not yet been created
+     * will be buffered. Any packets older than the prebuf_len
+     * will be discarded.
+     * If zero, default value is used.
+     */
+    unsigned long long prebuf_len;
 } roc_receiver_config;
 
 /** Interface configuration.

src/tests/roc_pipeline/test_receiver_source.cpp

@@ -2181,6 +2181,61 @@ TEST(receiver_source, timestamp_mapping_remixing) {
     CHECK(first_ts);
 }
 
+TEST(receiver_source, packet_buffer) {
+    enum { Rate = SampleRate, Chans = Chans_Stereo, MaxPackets = 10 };
+
+    init(Rate, Chans, Rate, Chans);
+
+    ReceiverSourceConfig config = make_default_config();
+    config.session_defaults.prebuf_len = 0;
+    ReceiverSource receiver(config, encoding_map, packet_pool, packet_buffer_pool,
+                            frame_pool, frame_buffer_pool, arena);
+    LONGS_EQUAL(status::StatusOK, receiver.init_status());
+
+    ReceiverSlot* slot = create_slot(receiver);
+    CHECK(slot);
+
+    packet::FifoQueue queue;
+    packet::FifoQueue source_queue;
+    packet::FifoQueue repair_queue;
+
+    packet::IWriter* source_endpoint_writer = create_transport_endpoint(
+        slot, address::Iface_AudioSource, address::Proto_RTP_RS8M_Source, dst_addr1);
+
+    packet::IWriter* repair_endpoint_writer = create_transport_endpoint(
+        slot, address::Iface_AudioRepair, address::Proto_RS8M_Repair, dst_addr2);
+
+    fec::BlockWriterConfig fec_config;
+
+    test::PacketWriter packet_writer(
+        arena, *source_endpoint_writer, *repair_endpoint_writer, encoding_map,
+        packet_factory, src_id1, src_addr1, dst_addr1, dst_addr2, PayloadType_Ch2,
+        packet::FEC_ReedSolomon_M8, fec_config);
+
+    // setup reader
+    test::FrameReader frame_reader(receiver, frame_factory);
+
+    packet_writer.write_packets(fec_config.n_source_packets, SamplesPerPacket,
+                                output_sample_spec);
+
+    for (int i = 0; i < ManyPackets; ++i) {
+        packet::PacketPtr pp;
+        LONGS_EQUAL(status::StatusOK, queue.read(pp, packet::ModeFetch));
+        CHECK(pp);
+
+        if (pp->flags() & packet::Packet::FlagAudio) {
+            UNSIGNED_LONGS_EQUAL(status::StatusOK, source_queue.write(pp));
+        }
+        if (pp->flags() & packet::Packet::FlagRepair) {
+            UNSIGNED_LONGS_EQUAL(status::StatusOK, repair_queue.write(pp));
+        }
+    }
+
+    LONGS_EQUAL(status::StatusOK, receiver.refresh(frame_reader.refresh_ts(), NULL));
+    frame_reader.read_nonzero_samples(SamplesPerFrame, output_sample_spec);
+    UNSIGNED_LONGS_EQUAL(1, receiver.num_sessions());
+}
+
 // Check receiver metrics for multiple remote participants (senders).
 TEST(receiver_source, metrics_participants) {
     enum { Rate = SampleRate, Chans = Chans_Stereo, MaxParties = 10 };

src/tools/roc_recv/cmdline.ggo

@@ -41,6 +41,9 @@ section "Options"
     option "no-play-timeout" - "No playback timeout, TIME units"
         string optional
 
+    option "prebuf-len" - "Length of packet prebuffer, TIME units"
+        string optional
+
     option "choppy-play-timeout" - "Choppy playback timeout, TIME units"
         string optional
 

src/tools/roc_recv/main.cpp

@@ -143,6 +143,19 @@ int main(int argc, char** argv) {
         }
     }
 
+    if (args.prebuf_len_given) {
+        core::nanoseconds_t prebuf_len = 0;
+        if (!core::parse_duration(args.prebuf_len_arg, prebuf_len)) {
+            roc_log(LogError, "invalid --prebuf-len");
+            return 1;
+        }
+        receiver_config.session_defaults.prebuf_len =
+            (core::nanoseconds_t)args.prebuf_len_arg;
+    } else {
+        receiver_config.session_defaults.prebuf_len =
+            receiver_config.session_defaults.latency.target_latency;
+    }
+
     if (args.choppy_play_timeout_given) {
         if (!core::parse_duration(
                 args.choppy_play_timeout_arg,