Add interval estimator to remote bitrate estimator

webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc

+/*
+ *  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 <memory>
+
+#include "webrtc/modules/audio_coding/audio_network_adaptor/smoothing_filter.h"
+#include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+namespace {
+
+// constexpr int kTimeConstantMs = 1000;

[minyue-webrtc, 2016/11/14 16:50:42]

can we remove these commented lines

[michaelt, 2016/11/15 09:41:59]

sure :) 

+// constexpr float kMaxAbsError = 0.0001f;
+constexpr int64_t kClockInitialTime = 123456;
+
+struct AimdRateControlStates {
+  std::unique_ptr<AimdRateControl> aimd_rate_control;
+  std::unique_ptr<SimulatedClock> simulated_clock;
+};
+
+AimdRateControlStates CreateAimdRateControlStates() {
+  AimdRateControlStates states;
+  states.aimd_rate_control.reset(new AimdRateControl());
+  states.simulated_clock.reset(new SimulatedClock(kClockInitialTime));
+  return states;
+}
+
+void InitToBitrate(const AimdRateControlStates& states,

[minyue-webrtc, 2016/11/14 16:50:42]

InitBitrate?

[michaelt, 2016/11/15 09:41:59]

Done.

+                   int bitrate,
+                   int64_t now_ms) {
+  // Reduce the bitrate by 1000 to compensate for the Update after SetEstimate.
+  bitrate -= 1000;
+
+  states.aimd_rate_control->SetEstimate(bitrate, now_ms);
+}
+
+void UpdateRateControl(const AimdRateControlStates& states,
+                       const BandwidthUsage& bandwidth_usage,
+                       int bitrate,
+                       int64_t now_ms) {
+  RateControlInput input(bandwidth_usage, rtc::Optional<uint32_t>(bitrate),
+                         now_ms);
+  states.aimd_rate_control->Update(&input, now_ms);
+  states.aimd_rate_control->UpdateBandwidthEstimate(now_ms);
+}
+
+}  // namespace
+
+TEST(AimdRateControlTest, MinNearMaxIncreaseRateOnLowBandwith) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 30000;
+  InitToBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(4000, states.aimd_rate_control->GetNearMaxIncreaseRateBps());
+}
+
+TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn90kbpsAn200msRtt) {

[minyue-webrtc, 2016/11/14 16:50:42]

An->And

[michaelt, 2016/11/15 09:41:59]

Done.

+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 90000;
+  InitToBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(5000, states.aimd_rate_control->GetNearMaxIncreaseRateBps());
+}
+
+TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn60kbpsAn100msRtt) {

[minyue-webrtc, 2016/11/14 16:50:42]

An->And

[michaelt, 2016/11/15 09:41:59]

Done.

+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 60000;
+  InitToBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  states.aimd_rate_control->SetRtt(100);
+  EXPECT_EQ(5000, states.aimd_rate_control->GetNearMaxIncreaseRateBps());
+}
+
+TEST(AimdRateControlTest, UnknownDropHightBeforeFirstOveruse) {

[minyue-webrtc, 2016/11/14 16:50:42]

Hight -> Height or maybe even rename to "UnknownBitrateDecrease..."

[michaelt, 2016/11/15 09:41:59]

Done.

+  auto states = CreateAimdRateControlStates();
+  EXPECT_EQ(rtc::Optional<int>(), states.aimd_rate_control->GetLastDecrease());
+}
+
+TEST(AimdRateControlTest, GetLastBitrateDrop) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 300000;
+  InitToBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  UpdateRateControl(states, kBwOverusing, kBitrate - 2000,
+                    states.simulated_clock->TimeInMilliseconds());
+  EXPECT_EQ(rtc::Optional<int>(46700),
+            states.aimd_rate_control->GetLastDecrease());
+}
+
+}  // namespace webrtc