Attach TransportFeedbackPacketLossTracker to ANA (PLR only)

webrtc/voice_engine/channel.cc

Index: webrtc/voice_engine/channel.cc
diff --git a/webrtc/voice_engine/channel.cc b/webrtc/voice_engine/channel.cc
index 2791f7f8b4ed555ed9da3e8d3f45ab6b9fa18171..8e5a4ca30ae12971fc2a981bd59c4150f8ef0885 100644
--- a/webrtc/voice_engine/channel.cc
+++ b/webrtc/voice_engine/channel.cc
@@ -32,6 +32,7 @@
 #include "webrtc/modules/rtp_rtcp/include/receive_statistics.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_receiver.h"
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_receiver_strategy.h"
 #include "webrtc/modules/utility/include/process_thread.h"
 #include "webrtc/system_wrappers/include/trace.h"
@@ -50,6 +51,11 @@ namespace {
 constexpr int64_t kMaxRetransmissionWindowMs = 1000;
 constexpr int64_t kMinRetransmissionWindowMs = 30;
 
+// TODO(elad.alon): Subsequent CL will make these values experiment-dependent.
+constexpr size_t kPacketLossTrackerMinWindowSize = 100;
+constexpr size_t kPacketLossTrackerMaxWindowSize = 200;
+constexpr size_t kPacketLossTrackerMinPairsNumForRplr = 50;
+
 }  // namespace
 
 const int kTelephoneEventAttenuationdB = 10;
@@ -202,13 +208,15 @@ class TransportFeedbackProxy : public TransportFeedbackObserver {
   }
 
   // Implements TransportFeedbackObserver.
-  void AddPacket(uint16_t sequence_number,
+  void AddPacket(uint32_t ssrc,
+                 uint16_t sequence_number,
                  size_t length,
                  int probe_cluster_id) override {
     RTC_DCHECK(pacer_thread_.CalledOnValidThread());
     rtc::CritScope lock(&crit_);
     if (feedback_observer_)
-      feedback_observer_->AddPacket(sequence_number, length, probe_cluster_id);
+      feedback_observer_->AddPacket(ssrc, sequence_number, length,
+                                    probe_cluster_id);
   }
   void OnTransportFeedback(const rtcp::TransportFeedback& feedback) override {
     RTC_DCHECK(network_thread_.CalledOnValidThread());
@@ -934,7 +942,12 @@ Channel::Channel(int32_t channelId,
       rtp_packet_sender_proxy_(new RtpPacketSenderProxy()),
       retransmission_rate_limiter_(new RateLimiter(Clock::GetRealTimeClock(),
                                                    kMaxRetransmissionWindowMs)),
-      decoder_factory_(config.acm_config.decoder_factory) {
+      decoder_factory_(config.acm_config.decoder_factory),
+      // TODO(elad.alon): Subsequent CL experiments with PLR source.
+      use_twcc_plr_for_ana_(false),
+      packet_loss_tracker_(kPacketLossTrackerMaxWindowSize,
+                           kPacketLossTrackerMinWindowSize,
+                           kPacketLossTrackerMinPairsNumForRplr) {
   WEBRTC_TRACE(kTraceMemory, kTraceVoice, VoEId(_instanceId, _channelId),
                "Channel::Channel() - ctor");
   AudioCodingModule::Config acm_config(config.acm_config);
@@ -1347,6 +1360,8 @@ void Channel::SetBitRate(int bitrate_bps, int64_t probing_interval_ms) {
 }
 
 void Channel::OnIncomingFractionLoss(int fraction_lost) {
+  if (use_twcc_plr_for_ana_)
+    return;
   audio_coding_->ModifyEncoder([&](std::unique_ptr<AudioEncoder>* encoder) {
     if (*encoder)
       (*encoder)->OnReceivedUplinkPacketLossFraction(fraction_lost / 255.0f);
@@ -2905,6 +2920,32 @@ void Channel::OnOverheadChanged(size_t overhead_bytes_per_packet) {
   UpdateOverheadForEncoder();
 }
 
+void Channel::HandleTransportFeedback(
+    const std::vector<uint16_t>& packets_sent_since_last_feedback,
+    const rtcp::TransportFeedback& feedback) {
+  for (uint16_t sent_sequence_number : packets_sent_since_last_feedback) {
+    packet_loss_tracker_.OnPacketAdded(sent_sequence_number);
+  }
+
+  // TODO(elad.alon): Needed even when !use_twcc_plr_for_ana_, because
+  // subsequent CLs will introduce pushing RPLR down to ANA, too, and that
+  // would happen unconditionally.
+  // (Rationale for unconditionality: it's cheap enough, and once
+  // experimentation is over, we either always do it or never do it, in which
+  // case the code involved will just be deleted.)
+  packet_loss_tracker_.OnReceivedTransportFeedback(feedback);
+
+  if (use_twcc_plr_for_ana_) {
+    rtc::Optional<float> plr = packet_loss_tracker_.GetPacketLossRate();
+    if (plr) {
+      audio_coding_->ModifyEncoder([&](std::unique_ptr<AudioEncoder>* encoder) {
+        if (*encoder)
+          (*encoder)->OnReceivedUplinkPacketLossFraction(*plr);
+      });
+    }
+  }
+}
+
 int Channel::RegisterExternalMediaProcessing(ProcessingTypes type,
                                              VoEMediaProcess& processObject) {
   WEBRTC_TRACE(kTraceInfo, kTraceVoice, VoEId(_instanceId, _channelId),