New ProbingCalculator class.

The ProbingCalculator class calculates and validates the results from
probing attempts.

BUG=webrtc:5859

Review-Url: https://codereview.webrtc.org/2121183002
Cr-Commit-Position: refs/heads/master@{#13589}

webrtc/modules/congestion_controller/BUILD.gn

@@ -14,6 +14,8 @@ source_set("congestion_controller") {
     "delay_based_bwe.cc",
     "delay_based_bwe.h",
     "include/congestion_controller.h",
+    "probe_bitrate_estimator.cc",
+    "probe_bitrate_estimator.h",
   ]
 
   configs += [ "../..:common_config" ]

webrtc/modules/congestion_controller/congestion_controller.gypi

@@ -18,9 +18,11 @@
       ],
       'sources': [
         'congestion_controller.cc',
-        'include/congestion_controller.h',
         'delay_based_bwe.cc',
         'delay_based_bwe.h',
+        'include/congestion_controller.h',
+        'probe_bitrate_estimator.cc',
+        'probe_bitrate_estimator.h',
       ],
       # TODO(jschuh): Bug 1348: fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],

webrtc/modules/congestion_controller/probe_bitrate_controller_unittest.cc

@@ -0,0 +1,127 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/congestion_controller/probe_bitrate_estimator.h"
+
+#include <vector>
+#include <utility>
+
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
+
+namespace webrtc {
+
+class TestProbeBitrateEstimator : public ::testing::Test {
+ public:
+  TestProbeBitrateEstimator() : probe_bitrate_estimator_() {}
+
+  void AddPacketFeedback(int probe_cluster_id,
+                         size_t size,
+                         int64_t send_time_ms,
+                         int64_t arrival_time_ms) {
+    PacketInfo info(arrival_time_ms, send_time_ms, 0, size, probe_cluster_id);
+    ProbingResult res = probe_bitrate_estimator_.PacketFeedback(info);
+    if (res.bps != ProbingResult::kNoEstimate)
+      results_.emplace_back(res.bps, res.timestamp);
+  }
+
+  void CheckResult(size_t index, int bps, int max_diff, int64_t timestamp) {
+    ASSERT_GT(results_.size(), index);
+    EXPECT_NEAR(results_[index].first, bps, max_diff);
+    EXPECT_EQ(results_[index].second, timestamp);
+  }
+
+ protected:
+  std::vector<std::pair<int, int64_t>> results_;
+  ProbeBitrateEstimator probe_bitrate_estimator_;
+};
+
+TEST_F(TestProbeBitrateEstimator, OneCluster) {
+  AddPacketFeedback(0, 1000, 0, 10);
+  AddPacketFeedback(0, 1000, 10, 20);
+  AddPacketFeedback(0, 1000, 20, 30);
+  AddPacketFeedback(0, 1000, 40, 50);
+
+  CheckResult(0, 100000, 10, 50);
+}
+
+TEST_F(TestProbeBitrateEstimator, FastReceive) {
+  AddPacketFeedback(0, 1000, 0, 15);
+  AddPacketFeedback(0, 1000, 10, 30);
+  AddPacketFeedback(0, 1000, 20, 40);
+  AddPacketFeedback(0, 1000, 40, 50);
+
+  CheckResult(0, 100000, 10, 50);
+}
+
+TEST_F(TestProbeBitrateEstimator, TooFastReceive) {
+  AddPacketFeedback(0, 1000, 0, 19);
+  AddPacketFeedback(0, 1000, 10, 30);
+  AddPacketFeedback(0, 1000, 20, 40);
+  AddPacketFeedback(0, 1000, 40, 50);
+
+  EXPECT_TRUE(results_.empty());
+}
+
+TEST_F(TestProbeBitrateEstimator, SlowReceive) {
+  AddPacketFeedback(0, 1000, 0, 10);
+  AddPacketFeedback(0, 1000, 10, 40);
+  AddPacketFeedback(0, 1000, 20, 70);
+  AddPacketFeedback(0, 1000, 40, 110);
+
+  CheckResult(0, 40000, 10, 110);
+}
+
+TEST_F(TestProbeBitrateEstimator, BurstReceive) {
+  AddPacketFeedback(0, 1000, 0, 50);
+  AddPacketFeedback(0, 1000, 10, 50);
+  AddPacketFeedback(0, 1000, 20, 50);
+  AddPacketFeedback(0, 1000, 40, 50);
+
+  EXPECT_TRUE(results_.empty());
+}
+
+TEST_F(TestProbeBitrateEstimator, MultipleClusters) {
+  AddPacketFeedback(0, 1000, 0, 10);
+  AddPacketFeedback(0, 1000, 10, 20);
+  AddPacketFeedback(0, 1000, 20, 30);
+  AddPacketFeedback(0, 1000, 40, 60);
+  AddPacketFeedback(0, 1000, 50, 60);
+
+  CheckResult(0, 80000, 10, 60);
+  CheckResult(1, 100000, 10, 60);
+
+  AddPacketFeedback(1, 1000, 60, 70);
+  AddPacketFeedback(1, 1000, 65, 77);
+  AddPacketFeedback(1, 1000, 70, 84);
+  AddPacketFeedback(1, 1000, 75, 90);
+
+  CheckResult(2, 200000, 10, 90);
+}
+
+TEST_F(TestProbeBitrateEstimator, OldProbe) {
+  AddPacketFeedback(0, 1000, 0, 10);
+  AddPacketFeedback(0, 1000, 10, 20);
+  AddPacketFeedback(0, 1000, 20, 30);
+
+  AddPacketFeedback(1, 1000, 60, 70);
+  AddPacketFeedback(1, 1000, 65, 77);
+  AddPacketFeedback(1, 1000, 70, 84);
+  AddPacketFeedback(1, 1000, 75, 90);
+
+  CheckResult(0, 200000, 10, 90);
+
+  AddPacketFeedback(0, 1000, 40, 60);
+
+  EXPECT_EQ(1ul, results_.size());
+}
+
+}  // namespace webrtc

webrtc/modules/congestion_controller/probe_bitrate_estimator.cc

@@ -0,0 +1,109 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/congestion_controller/probe_bitrate_estimator.h"
+
+#include <algorithm>
+
+#include "webrtc/base/logging.h"
+
+namespace {
+// Max number of saved clusters.
+constexpr size_t kMaxNumSavedClusters = 5;
+
+// The minumum number of probes we need for a valid cluster.
+constexpr int kMinNumProbesValidCluster = 4;
+
+// The maximum (receive rate)/(send rate) ratio for a valid estimate.
+constexpr float kValidRatio = 1.2f;
+}
+
+namespace webrtc {
+
+ProbingResult::ProbingResult() : bps(kNoEstimate), timestamp(0) {}
+
+ProbingResult::ProbingResult(int bps, int64_t timestamp)
+    : bps(bps), timestamp(timestamp) {}
+
+ProbeBitrateEstimator::ProbeBitrateEstimator() : last_valid_cluster_id_(0) {}
+
+ProbingResult ProbeBitrateEstimator::PacketFeedback(
+    const PacketInfo& packet_info) {
+  // If this is not a probing packet or if this probing packet
+  // belongs to an old cluster, do nothing.
+  if (packet_info.probe_cluster_id == PacketInfo::kNotAProbe ||
+      packet_info.probe_cluster_id < last_valid_cluster_id_) {
+    return ProbingResult();
+  }
+
+  AggregatedCluster* cluster = &clusters_[packet_info.probe_cluster_id];
+  cluster->first_send_ms =
+      std::min(cluster->first_send_ms, packet_info.send_time_ms);
+  cluster->last_send_ms =
+      std::max(cluster->last_send_ms, packet_info.send_time_ms);
+  cluster->first_receive_ms =
+      std::min(cluster->first_receive_ms, packet_info.arrival_time_ms);
+  cluster->last_receive_ms =
+      std::max(cluster->last_receive_ms, packet_info.arrival_time_ms);
+  cluster->size += packet_info.payload_size;
+  cluster->num_probes += 1;
+
+  // Clean up old clusters.
+  while (clusters_.size() > kMaxNumSavedClusters)
+    clusters_.erase(clusters_.begin());
+
+  if (cluster->num_probes < kMinNumProbesValidCluster)
+    return ProbingResult();
+
+  int send_interval_ms = cluster->last_send_ms - cluster->first_send_ms;
+  int receive_interval_ms =
+      cluster->last_receive_ms - cluster->first_receive_ms;
+
+  if (send_interval_ms == 0 || receive_interval_ms == 0) {
+    LOG(LS_INFO) << "Probing unsuccessful, invalid send/receive interval"
+                 << " [cluster id: " << packet_info.probe_cluster_id
+                 << "] [send interval: " << send_interval_ms << " ms]"
+                 << " [receive interval: " << receive_interval_ms << " ms]";
+
+    return ProbingResult();
+  }
+
+  float send_bps = static_cast<float>(cluster->size) / send_interval_ms * 1000;
+  float receive_bps =
+      static_cast<float>(cluster->size) / receive_interval_ms * 1000;
+  float ratio = receive_bps / send_bps;
+  if (ratio > kValidRatio) {
+    LOG(LS_INFO) << "Probing unsuccessful, receive/send ratio too high"
+                 << " [cluster id: " << packet_info.probe_cluster_id
+                 << "] [send: " << cluster->size << " bytes / "
+                 << send_interval_ms << " ms = " << send_bps / 1000 << " kb/s]"
+                 << " [receive: " << cluster->size << " bytes / "
+                 << receive_interval_ms << " ms = " << receive_bps / 1000
+                 << " kb/s]"
+                 << " [ratio: " << receive_bps / 1000 << " / "
+                 << send_bps / 1000 << " = " << ratio << " > kValidRatio ("
+                 << kValidRatio << ")]";
+
+    return ProbingResult();
+  }
+  // We have a valid estimate.
+  int result_bps = std::min(send_bps, receive_bps);
+  last_valid_cluster_id_ = packet_info.probe_cluster_id;
+  LOG(LS_INFO) << "Probing successful"
+               << " [cluster id: " << packet_info.probe_cluster_id
+               << "] [send: " << cluster->size << " bytes / "
+               << send_interval_ms << " ms = " << send_bps / 1000 << " kb/s]"
+               << " [receive: " << cluster->size << " bytes / "
+               << receive_interval_ms << " ms = " << receive_bps / 1000
+               << " kb/s]";
+
+  return ProbingResult(result_bps, packet_info.arrival_time_ms);
+}
+}  // namespace webrtc

webrtc/modules/congestion_controller/probe_bitrate_estimator.h

@@ -0,0 +1,56 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_BITRATE_ESTIMATOR_H_
+#define WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_BITRATE_ESTIMATOR_H_
+
+#include <map>
+#include <limits>
+
+#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+
+namespace webrtc {
+
+struct ProbingResult {
+  static constexpr int kNoEstimate = -1;
+
+  ProbingResult();
+  ProbingResult(int bps, int64_t timestamp);
+
+  int bps;
+  int64_t timestamp;
+};
+
+class ProbeBitrateEstimator {
+ public:
+  ProbeBitrateEstimator();
+
+  // Should be called for every packet we receive feedback about. If the
+  // packet was used for probing it will validate/calculate the resulting
+  // bitrate and return the result.
+  ProbingResult PacketFeedback(const PacketInfo& packet_info);
+
+ private:
+  struct AggregatedCluster {
+    int num_probes = 0;
+    int64_t first_send_ms = std::numeric_limits<int64_t>::max();
+    int64_t last_send_ms = 0;
+    int64_t first_receive_ms = std::numeric_limits<int64_t>::max();
+    int64_t last_receive_ms = 0;
+    size_t size = 0;
+  };
+
+  std::map<int, AggregatedCluster> clusters_;
+  int last_valid_cluster_id_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_BITRATE_ESTIMATOR_H_

webrtc/modules/modules.gyp

@@ -277,6 +277,7 @@
             'congestion_controller/delay_based_bwe_unittest.cc',
             'congestion_controller/delay_based_bwe_unittest_helper.cc',
             'congestion_controller/delay_based_bwe_unittest_helper.h',
+            'congestion_controller/probe_bitrate_controller_unittest.cc',
             'media_file/media_file_unittest.cc',
             'module_common_types_unittest.cc',
             'pacing/bitrate_prober_unittest.cc',