Home | History | Annotate | Download | only in bitrate_controller
      1 /*
      2  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #include "testing/gtest/include/gtest/gtest.h"
     12 
     13 #include <algorithm>
     14 #include <vector>
     15 
     16 #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h"
     17 #include "webrtc/modules/rtp_rtcp/interface/rtp_rtcp_defines.h"
     18 
     19 using webrtc::RtcpBandwidthObserver;
     20 using webrtc::BitrateObserver;
     21 using webrtc::BitrateController;
     22 
     23 uint8_t WeightedLoss(int num_packets1, uint8_t fraction_loss1,
     24                      int num_packets2, uint8_t fraction_loss2) {
     25   int weighted_sum = num_packets1 * fraction_loss1 +
     26       num_packets2 * fraction_loss2;
     27   int total_num_packets = num_packets1 + num_packets2;
     28   return (weighted_sum + total_num_packets / 2) / total_num_packets;
     29 }
     30 
     31 webrtc::RTCPReportBlock CreateReportBlock(
     32     uint32_t remote_ssrc, uint32_t source_ssrc,
     33     uint8_t fraction_lost, uint32_t extended_high_sequence_number) {
     34   return webrtc::RTCPReportBlock(remote_ssrc, source_ssrc, fraction_lost, 0,
     35                                  extended_high_sequence_number, 0, 0, 0);
     36 }
     37 
     38 class TestBitrateObserver: public BitrateObserver {
     39  public:
     40   TestBitrateObserver()
     41       : last_bitrate_(0),
     42         last_fraction_loss_(0),
     43         last_rtt_(0) {
     44   }
     45 
     46   virtual void OnNetworkChanged(const uint32_t bitrate,
     47                                 const uint8_t fraction_loss,
     48                                 const uint32_t rtt) {
     49     last_bitrate_ = bitrate;
     50     last_fraction_loss_ = fraction_loss;
     51     last_rtt_ = rtt;
     52   }
     53   uint32_t last_bitrate_;
     54   uint8_t last_fraction_loss_;
     55   uint32_t last_rtt_;
     56 };
     57 
     58 class BitrateControllerTest : public ::testing::Test {
     59  protected:
     60   BitrateControllerTest() : clock_(0), enforce_min_bitrate_(true) {}
     61   ~BitrateControllerTest() {}
     62 
     63   virtual void SetUp() {
     64     controller_ = BitrateController::CreateBitrateController(
     65         &clock_, enforce_min_bitrate_);
     66     bandwidth_observer_ = controller_->CreateRtcpBandwidthObserver();
     67   }
     68 
     69   virtual void TearDown() {
     70     delete bandwidth_observer_;
     71     delete controller_;
     72   }
     73 
     74   webrtc::SimulatedClock clock_;
     75   bool enforce_min_bitrate_;
     76   BitrateController* controller_;
     77   RtcpBandwidthObserver* bandwidth_observer_;
     78 };
     79 
     80 TEST_F(BitrateControllerTest, Basic) {
     81   TestBitrateObserver bitrate_observer;
     82   controller_->SetBitrateObserver(&bitrate_observer, 200000, 100000, 300000);
     83   controller_->RemoveBitrateObserver(&bitrate_observer);
     84 }
     85 
     86 TEST_F(BitrateControllerTest, UpdatingBitrateObserver) {
     87   TestBitrateObserver bitrate_observer;
     88   controller_->SetBitrateObserver(&bitrate_observer, 200000, 100000, 1500000);
     89   clock_.AdvanceTimeMilliseconds(25);
     90   controller_->Process();
     91   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
     92 
     93   controller_->SetBitrateObserver(&bitrate_observer, 1500000, 100000, 1500000);
     94   clock_.AdvanceTimeMilliseconds(25);
     95   controller_->Process();
     96   EXPECT_EQ(1500000u, bitrate_observer.last_bitrate_);
     97 
     98   controller_->SetBitrateObserver(&bitrate_observer, 500000, 100000, 1500000);
     99   clock_.AdvanceTimeMilliseconds(25);
    100   controller_->Process();
    101   EXPECT_EQ(1500000u, bitrate_observer.last_bitrate_);
    102 }
    103 
    104 TEST_F(BitrateControllerTest, OneBitrateObserverOneRtcpObserver) {
    105   TestBitrateObserver bitrate_observer;
    106   controller_->SetBitrateObserver(&bitrate_observer, 200000, 100000, 300000);
    107 
    108   // Receive a high remb, test bitrate inc.
    109   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    110   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
    111   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    112   EXPECT_EQ(0u, bitrate_observer.last_rtt_);
    113 
    114   // Test bitrate increase 8% per second.
    115   webrtc::ReportBlockList report_blocks;
    116   report_blocks.push_back(CreateReportBlock(1, 2, 0, 1));
    117   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 1);
    118   EXPECT_EQ(217000u, bitrate_observer.last_bitrate_);
    119   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    120   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    121 
    122   report_blocks.clear();
    123   report_blocks.push_back(CreateReportBlock(1, 2, 0, 21));
    124   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 1001);
    125   EXPECT_EQ(235360u, bitrate_observer.last_bitrate_);
    126   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    127   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    128 
    129   report_blocks.clear();
    130   report_blocks.push_back(CreateReportBlock(1, 2, 0, 41));
    131   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 2001);
    132   EXPECT_EQ(255189u, bitrate_observer.last_bitrate_);
    133 
    134   report_blocks.clear();
    135   report_blocks.push_back(CreateReportBlock(1, 2, 0, 61));
    136   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 3001);
    137   EXPECT_EQ(276604u, bitrate_observer.last_bitrate_);
    138 
    139   report_blocks.clear();
    140   report_blocks.push_back(CreateReportBlock(1, 2, 0, 801));
    141   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 4001);
    142   EXPECT_EQ(299732u, bitrate_observer.last_bitrate_);
    143 
    144   // Reach max cap.
    145   report_blocks.clear();
    146   report_blocks.push_back(CreateReportBlock(1, 2, 0, 101));
    147   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 5001);
    148   EXPECT_EQ(300000u, bitrate_observer.last_bitrate_);
    149 
    150   report_blocks.clear();
    151   report_blocks.push_back(CreateReportBlock(1, 2, 0, 141));
    152   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 7001);
    153   EXPECT_EQ(300000u, bitrate_observer.last_bitrate_);
    154 
    155   // Test that a low REMB trigger immediately.
    156   bandwidth_observer_->OnReceivedEstimatedBitrate(250000);
    157   EXPECT_EQ(250000u, bitrate_observer.last_bitrate_);
    158   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    159   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    160 
    161   bandwidth_observer_->OnReceivedEstimatedBitrate(1000);
    162   EXPECT_EQ(100000u, bitrate_observer.last_bitrate_);  // Min cap.
    163   controller_->RemoveBitrateObserver(&bitrate_observer);
    164 }
    165 
    166 TEST_F(BitrateControllerTest, OneBitrateObserverTwoRtcpObservers) {
    167   TestBitrateObserver bitrate_observer;
    168   controller_->SetBitrateObserver(&bitrate_observer, 200000, 100000, 300000);
    169 
    170   RtcpBandwidthObserver* second_bandwidth_observer =
    171       controller_->CreateRtcpBandwidthObserver();
    172 
    173   // Receive a high remb, test bitrate inc.
    174   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    175   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
    176   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    177   EXPECT_EQ(0u, bitrate_observer.last_rtt_);
    178 
    179   // Test start bitrate.
    180   webrtc::ReportBlockList report_blocks;
    181   report_blocks.push_back(CreateReportBlock(1, 2, 0, 1));
    182   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 1);
    183   second_bandwidth_observer->OnReceivedRtcpReceiverReport(
    184       report_blocks, 100, 1);
    185   EXPECT_EQ(217000u, bitrate_observer.last_bitrate_);
    186   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    187   EXPECT_EQ(100u, bitrate_observer.last_rtt_);
    188 
    189   // Test bitrate increase 8% per second.
    190   report_blocks.clear();
    191   report_blocks.push_back(CreateReportBlock(1, 2, 0, 21));
    192   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 501);
    193   second_bandwidth_observer->OnReceivedRtcpReceiverReport(report_blocks, 100,
    194                                                           1001);
    195   EXPECT_EQ(235360u, bitrate_observer.last_bitrate_);
    196   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    197   EXPECT_EQ(100u, bitrate_observer.last_rtt_);
    198 
    199   // Extra report should not change estimate.
    200   report_blocks.clear();
    201   report_blocks.push_back(CreateReportBlock(1, 2, 0, 31));
    202   second_bandwidth_observer->OnReceivedRtcpReceiverReport(report_blocks, 100,
    203                                                           1501);
    204   EXPECT_EQ(235360u, bitrate_observer.last_bitrate_);
    205 
    206   report_blocks.clear();
    207   report_blocks.push_back(CreateReportBlock(1, 2, 0, 41));
    208   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 2001);
    209   EXPECT_EQ(255189u, bitrate_observer.last_bitrate_);
    210 
    211   // Second report should not change estimate.
    212   report_blocks.clear();
    213   report_blocks.push_back(CreateReportBlock(1, 2, 0, 41));
    214   second_bandwidth_observer->OnReceivedRtcpReceiverReport(report_blocks, 100,
    215                                                           2001);
    216   EXPECT_EQ(255189u, bitrate_observer.last_bitrate_);
    217 
    218   // Reports from only one bandwidth observer is ok.
    219   report_blocks.clear();
    220   report_blocks.push_back(CreateReportBlock(1, 2, 0, 61));
    221   second_bandwidth_observer->OnReceivedRtcpReceiverReport(report_blocks, 50,
    222                                                           3001);
    223   EXPECT_EQ(276604u, bitrate_observer.last_bitrate_);
    224 
    225   report_blocks.clear();
    226   report_blocks.push_back(CreateReportBlock(1, 2, 0, 81));
    227   second_bandwidth_observer->OnReceivedRtcpReceiverReport(report_blocks, 50,
    228                                                           4001);
    229   EXPECT_EQ(299732u, bitrate_observer.last_bitrate_);
    230 
    231   // Reach max cap.
    232   report_blocks.clear();
    233   report_blocks.push_back(CreateReportBlock(1, 2, 0, 121));
    234   second_bandwidth_observer->OnReceivedRtcpReceiverReport(
    235       report_blocks, 50, 5001);
    236   EXPECT_EQ(300000u, bitrate_observer.last_bitrate_);
    237 
    238   report_blocks.clear();
    239   report_blocks.push_back(CreateReportBlock(1, 2, 0, 141));
    240   second_bandwidth_observer->OnReceivedRtcpReceiverReport(
    241       report_blocks, 50, 6001);
    242   EXPECT_EQ(300000u, bitrate_observer.last_bitrate_);
    243 
    244   // Test that a low REMB trigger immediately.
    245   // We don't care which bandwidth observer that delivers the REMB.
    246   second_bandwidth_observer->OnReceivedEstimatedBitrate(250000);
    247   EXPECT_EQ(250000u, bitrate_observer.last_bitrate_);
    248   EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    249   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    250 
    251   // Min cap.
    252   bandwidth_observer_->OnReceivedEstimatedBitrate(1000);
    253   EXPECT_EQ(100000u, bitrate_observer.last_bitrate_);
    254   controller_->RemoveBitrateObserver(&bitrate_observer);
    255   delete second_bandwidth_observer;
    256 }
    257 
    258 TEST_F(BitrateControllerTest, OneBitrateObserverMultipleReportBlocks) {
    259   TestBitrateObserver bitrate_observer;
    260   uint32_t sequence_number[2] = {0, 0xFF00};
    261   const uint32_t kStartBitrate = 200000;
    262   const uint32_t kMinBitrate = 100000;
    263   const uint32_t kMaxBitrate = 300000;
    264   controller_->SetBitrateObserver(&bitrate_observer, kStartBitrate, kMinBitrate,
    265                                   kMaxBitrate);
    266 
    267   // Receive a high REMB, test bitrate increase.
    268   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    269 
    270   webrtc::ReportBlockList report_blocks;
    271   int64_t time_ms = 1001;
    272   uint32_t last_bitrate = 0;
    273   // Ramp up to max bitrate.
    274   for (int i = 0; i < 6; ++i) {
    275     report_blocks.push_back(CreateReportBlock(1, 2, 0, sequence_number[0]));
    276     report_blocks.push_back(CreateReportBlock(1, 3, 0, sequence_number[1]));
    277     bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50,
    278                                                       time_ms);
    279     EXPECT_GT(bitrate_observer.last_bitrate_, last_bitrate);
    280     EXPECT_EQ(0, bitrate_observer.last_fraction_loss_);
    281     EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    282     last_bitrate = bitrate_observer.last_bitrate_;
    283     time_ms += 1000;
    284     sequence_number[0] += 20;
    285     sequence_number[1] += 1;
    286     report_blocks.clear();
    287   }
    288 
    289   EXPECT_EQ(kMaxBitrate, bitrate_observer.last_bitrate_);
    290 
    291   // Packet loss on the first stream. Verify that bitrate decreases.
    292   report_blocks.push_back(CreateReportBlock(1, 2, 50, sequence_number[0]));
    293   report_blocks.push_back(CreateReportBlock(1, 3, 0, sequence_number[1]));
    294   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, time_ms);
    295   EXPECT_LT(bitrate_observer.last_bitrate_, last_bitrate);
    296   EXPECT_EQ(WeightedLoss(20, 50, 1, 0), bitrate_observer.last_fraction_loss_);
    297   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    298   last_bitrate = bitrate_observer.last_bitrate_;
    299   sequence_number[0] += 20;
    300   sequence_number[1] += 20;
    301   time_ms += 1000;
    302   report_blocks.clear();
    303 
    304   // Packet loss on the second stream. Verify that bitrate decreases.
    305   report_blocks.push_back(CreateReportBlock(1, 2, 0, sequence_number[0]));
    306   report_blocks.push_back(CreateReportBlock(1, 3, 75, sequence_number[1]));
    307   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, time_ms);
    308   EXPECT_LT(bitrate_observer.last_bitrate_, last_bitrate);
    309   EXPECT_EQ(WeightedLoss(20, 0, 20, 75), bitrate_observer.last_fraction_loss_);
    310   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    311   last_bitrate = bitrate_observer.last_bitrate_;
    312   sequence_number[0] += 20;
    313   sequence_number[1] += 1;
    314   time_ms += 1000;
    315   report_blocks.clear();
    316 
    317   // All packets lost on stream with few packets, no back-off.
    318   report_blocks.push_back(CreateReportBlock(1, 2, 1, sequence_number[0]));
    319   report_blocks.push_back(CreateReportBlock(1, 3, 255, sequence_number[1]));
    320   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, time_ms);
    321   EXPECT_EQ(bitrate_observer.last_bitrate_, last_bitrate);
    322   EXPECT_EQ(WeightedLoss(20, 1, 1, 255), bitrate_observer.last_fraction_loss_);
    323   EXPECT_EQ(50u, bitrate_observer.last_rtt_);
    324   last_bitrate = bitrate_observer.last_bitrate_;
    325   sequence_number[0] += 20;
    326   sequence_number[1] += 1;
    327   report_blocks.clear();
    328 }
    329 
    330 TEST_F(BitrateControllerTest, TwoBitrateObserversOneRtcpObserver) {
    331   TestBitrateObserver bitrate_observer_1;
    332   TestBitrateObserver bitrate_observer_2;
    333   controller_->SetBitrateObserver(&bitrate_observer_2, 200000, 200000, 300000);
    334   controller_->SetBitrateObserver(&bitrate_observer_1, 200000, 100000, 300000);
    335 
    336   // Receive a high remb, test bitrate inc.
    337   // Test too low start bitrate, hence lower than sum of min.
    338   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    339   EXPECT_EQ(100000u, bitrate_observer_1.last_bitrate_);
    340   EXPECT_EQ(0, bitrate_observer_1.last_fraction_loss_);
    341   EXPECT_EQ(0u, bitrate_observer_1.last_rtt_);
    342 
    343   // Test bitrate increase 8% per second, distributed equally.
    344   webrtc::ReportBlockList report_blocks;
    345   report_blocks.push_back(CreateReportBlock(1, 2, 0, 1));
    346   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 1001);
    347   EXPECT_EQ(112500u, bitrate_observer_1.last_bitrate_);
    348   EXPECT_EQ(0, bitrate_observer_1.last_fraction_loss_);
    349   EXPECT_EQ(50u, bitrate_observer_1.last_rtt_);
    350 
    351   EXPECT_EQ(212500u, bitrate_observer_2.last_bitrate_);
    352   EXPECT_EQ(0, bitrate_observer_2.last_fraction_loss_);
    353   EXPECT_EQ(50u, bitrate_observer_2.last_rtt_);
    354 
    355   report_blocks.clear();
    356   report_blocks.push_back(CreateReportBlock(1, 2, 0, 41));
    357   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 2001);
    358   EXPECT_EQ(126000u, bitrate_observer_1.last_bitrate_);
    359   EXPECT_EQ(226000u, bitrate_observer_2.last_bitrate_);
    360 
    361   report_blocks.clear();
    362   report_blocks.push_back(CreateReportBlock(1, 2, 0, 61));
    363   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 3001);
    364   EXPECT_EQ(140580u, bitrate_observer_1.last_bitrate_);
    365   EXPECT_EQ(240580u, bitrate_observer_2.last_bitrate_);
    366 
    367   // Check that the bitrate sum honor our REMB.
    368   report_blocks.clear();
    369   report_blocks.push_back(CreateReportBlock(1, 2, 0, 101));
    370   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 5001);
    371   EXPECT_EQ(150000u, bitrate_observer_1.last_bitrate_);
    372   EXPECT_EQ(250000u, bitrate_observer_2.last_bitrate_);
    373 
    374   // Remove REMB cap, higher than sum of max.
    375   bandwidth_observer_->OnReceivedEstimatedBitrate(700000);
    376 
    377   report_blocks.clear();
    378   report_blocks.push_back(CreateReportBlock(1, 2, 0, 121));
    379   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 6001);
    380   EXPECT_EQ(166500u, bitrate_observer_1.last_bitrate_);
    381   EXPECT_EQ(266500u, bitrate_observer_2.last_bitrate_);
    382 
    383   report_blocks.clear();
    384   report_blocks.push_back(CreateReportBlock(1, 2, 0, 141));
    385   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 7001);
    386   EXPECT_EQ(184320u, bitrate_observer_1.last_bitrate_);
    387   EXPECT_EQ(284320u, bitrate_observer_2.last_bitrate_);
    388 
    389   report_blocks.clear();
    390   report_blocks.push_back(CreateReportBlock(1, 2, 0, 161));
    391   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 8001);
    392   EXPECT_EQ(207130u, bitrate_observer_1.last_bitrate_);
    393   EXPECT_EQ(300000u, bitrate_observer_2.last_bitrate_);  // Max cap.
    394 
    395   report_blocks.clear();
    396   report_blocks.push_back(CreateReportBlock(1, 2, 0, 181));
    397   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 9001);
    398   EXPECT_EQ(248700u, bitrate_observer_1.last_bitrate_);
    399   EXPECT_EQ(300000u, bitrate_observer_2.last_bitrate_);
    400 
    401   report_blocks.clear();
    402   report_blocks.push_back(CreateReportBlock(1, 2, 0, 201));
    403   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 10001);
    404   EXPECT_EQ(293596u, bitrate_observer_1.last_bitrate_);
    405   EXPECT_EQ(300000u, bitrate_observer_2.last_bitrate_);
    406 
    407   report_blocks.clear();
    408   report_blocks.push_back(CreateReportBlock(1, 2, 0, 221));
    409   bandwidth_observer_->OnReceivedRtcpReceiverReport(report_blocks, 50, 11001);
    410   EXPECT_EQ(300000u, bitrate_observer_1.last_bitrate_);  // Max cap.
    411   EXPECT_EQ(300000u, bitrate_observer_2.last_bitrate_);
    412 
    413   // Test that a low REMB trigger immediately.
    414   bandwidth_observer_->OnReceivedEstimatedBitrate(350000);
    415   EXPECT_EQ(125000u, bitrate_observer_1.last_bitrate_);
    416   EXPECT_EQ(0, bitrate_observer_1.last_fraction_loss_);
    417   EXPECT_EQ(50u, bitrate_observer_1.last_rtt_);
    418   EXPECT_EQ(225000u, bitrate_observer_2.last_bitrate_);
    419   EXPECT_EQ(0, bitrate_observer_2.last_fraction_loss_);
    420   EXPECT_EQ(50u, bitrate_observer_2.last_rtt_);
    421 
    422   bandwidth_observer_->OnReceivedEstimatedBitrate(1000);
    423   EXPECT_EQ(100000u, bitrate_observer_1.last_bitrate_);  // Min cap.
    424   EXPECT_EQ(200000u, bitrate_observer_2.last_bitrate_);  // Min cap.
    425   controller_->RemoveBitrateObserver(&bitrate_observer_1);
    426   controller_->RemoveBitrateObserver(&bitrate_observer_2);
    427 }
    428 
    429 TEST_F(BitrateControllerTest, SetReservedBitrate) {
    430   TestBitrateObserver bitrate_observer;
    431   controller_->SetBitrateObserver(&bitrate_observer, 200000, 100000, 300000);
    432 
    433   // Receive successively lower REMBs, verify the reserved bitrate is deducted.
    434 
    435   controller_->SetReservedBitrate(0);
    436   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    437   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
    438   controller_->SetReservedBitrate(50000);
    439   bandwidth_observer_->OnReceivedEstimatedBitrate(400000);
    440   EXPECT_EQ(150000u, bitrate_observer.last_bitrate_);
    441 
    442   controller_->SetReservedBitrate(0);
    443   bandwidth_observer_->OnReceivedEstimatedBitrate(250000);
    444   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
    445   controller_->SetReservedBitrate(50000);
    446   bandwidth_observer_->OnReceivedEstimatedBitrate(250000);
    447   EXPECT_EQ(150000u, bitrate_observer.last_bitrate_);
    448 
    449   controller_->SetReservedBitrate(0);
    450   bandwidth_observer_->OnReceivedEstimatedBitrate(200000);
    451   EXPECT_EQ(200000u, bitrate_observer.last_bitrate_);
    452   controller_->SetReservedBitrate(30000);
    453   bandwidth_observer_->OnReceivedEstimatedBitrate(200000);
    454   EXPECT_EQ(170000u, bitrate_observer.last_bitrate_);
    455 
    456   controller_->SetReservedBitrate(0);
    457   bandwidth_observer_->OnReceivedEstimatedBitrate(160000);
    458   EXPECT_EQ(160000u, bitrate_observer.last_bitrate_);
    459   controller_->SetReservedBitrate(30000);
    460   bandwidth_observer_->OnReceivedEstimatedBitrate(160000);
    461   EXPECT_EQ(130000u, bitrate_observer.last_bitrate_);
    462 
    463   controller_->SetReservedBitrate(0);
    464   bandwidth_observer_->OnReceivedEstimatedBitrate(120000);
    465   EXPECT_EQ(120000u, bitrate_observer.last_bitrate_);
    466   controller_->SetReservedBitrate(10000);
    467   bandwidth_observer_->OnReceivedEstimatedBitrate(120000);
    468   EXPECT_EQ(110000u, bitrate_observer.last_bitrate_);
    469 
    470   controller_->SetReservedBitrate(0);
    471   bandwidth_observer_->OnReceivedEstimatedBitrate(120000);
    472   EXPECT_EQ(120000u, bitrate_observer.last_bitrate_);
    473   controller_->SetReservedBitrate(50000);
    474   bandwidth_observer_->OnReceivedEstimatedBitrate(120000);
    475   EXPECT_EQ(100000u, bitrate_observer.last_bitrate_);
    476 
    477   controller_->SetReservedBitrate(10000);
    478   bandwidth_observer_->OnReceivedEstimatedBitrate(0);
    479   EXPECT_EQ(100000u, bitrate_observer.last_bitrate_);
    480 
    481   controller_->RemoveBitrateObserver(&bitrate_observer);
    482 }
    483 
    484 class BitrateControllerTestNoEnforceMin : public BitrateControllerTest {
    485  protected:
    486   BitrateControllerTestNoEnforceMin() : BitrateControllerTest() {
    487     enforce_min_bitrate_ = false;
    488   }
    489 };
    490 
    491 // The following three tests verify that the EnforceMinBitrate() method works
    492 // as intended.
    493 TEST_F(BitrateControllerTestNoEnforceMin, OneBitrateObserver) {
    494   TestBitrateObserver bitrate_observer_1;
    495   controller_->SetBitrateObserver(&bitrate_observer_1, 200000, 100000, 400000);
    496 
    497   // High REMB.
    498   bandwidth_observer_->OnReceivedEstimatedBitrate(150000);
    499   EXPECT_EQ(150000u, bitrate_observer_1.last_bitrate_);
    500 
    501   // Low REMB.
    502   bandwidth_observer_->OnReceivedEstimatedBitrate(10000);
    503   EXPECT_EQ(10000u, bitrate_observer_1.last_bitrate_);
    504 
    505   // Keeps at least 10 kbps.
    506   bandwidth_observer_->OnReceivedEstimatedBitrate(9000);
    507   EXPECT_EQ(10000u, bitrate_observer_1.last_bitrate_);
    508 
    509   controller_->RemoveBitrateObserver(&bitrate_observer_1);
    510 }
    511 
    512 TEST_F(BitrateControllerTestNoEnforceMin, SetReservedBitrate) {
    513   TestBitrateObserver bitrate_observer_1;
    514   controller_->SetBitrateObserver(&bitrate_observer_1, 200000, 100000, 400000);
    515   controller_->SetReservedBitrate(10000);
    516 
    517   // High REMB.
    518   bandwidth_observer_->OnReceivedEstimatedBitrate(150000);
    519   EXPECT_EQ(140000u, bitrate_observer_1.last_bitrate_);
    520 
    521   // Low REMB.
    522   bandwidth_observer_->OnReceivedEstimatedBitrate(15000);
    523   EXPECT_EQ(5000u, bitrate_observer_1.last_bitrate_);
    524 
    525   // Keeps at least 10 kbps.
    526   bandwidth_observer_->OnReceivedEstimatedBitrate(9000);
    527   EXPECT_EQ(0u, bitrate_observer_1.last_bitrate_);
    528 
    529   controller_->RemoveBitrateObserver(&bitrate_observer_1);
    530 }
    531 
    532 TEST_F(BitrateControllerTestNoEnforceMin, ThreeBitrateObservers) {
    533   TestBitrateObserver bitrate_observer_1;
    534   TestBitrateObserver bitrate_observer_2;
    535   TestBitrateObserver bitrate_observer_3;
    536   // Set up the observers with min bitrates at 100000, 200000, and 300000.
    537   // Note: The start bitrate of bitrate_observer_1 (700000) is used as the
    538   // overall start bitrate.
    539   controller_->SetBitrateObserver(&bitrate_observer_1, 700000, 100000, 400000);
    540   controller_->SetBitrateObserver(&bitrate_observer_2, 200000, 200000, 400000);
    541   controller_->SetBitrateObserver(&bitrate_observer_3, 200000, 300000, 400000);
    542 
    543   // High REMB. Make sure the controllers get a fair share of the surplus
    544   // (i.e., what is left after each controller gets its min rate).
    545   bandwidth_observer_->OnReceivedEstimatedBitrate(690000);
    546   // Verify that each observer gets its min rate (sum of min rates is 600000),
    547   // and that the remaining 90000 is divided equally among the three.
    548   EXPECT_EQ(130000u, bitrate_observer_1.last_bitrate_);
    549   EXPECT_EQ(230000u, bitrate_observer_2.last_bitrate_);
    550   EXPECT_EQ(330000u, bitrate_observer_3.last_bitrate_);
    551 
    552   // High REMB, but below the sum of min bitrates.
    553   bandwidth_observer_->OnReceivedEstimatedBitrate(500000);
    554   // Verify that the first and second observers get their min bitrates, and the
    555   // third gets the remainder.
    556   EXPECT_EQ(100000u, bitrate_observer_1.last_bitrate_);  // Min bitrate.
    557   EXPECT_EQ(200000u, bitrate_observer_2.last_bitrate_);  // Min bitrate.
    558   EXPECT_EQ(200000u, bitrate_observer_3.last_bitrate_);  // Remainder.
    559 
    560   // Low REMB.
    561   bandwidth_observer_->OnReceivedEstimatedBitrate(10000);
    562   // Verify that the first observer gets all the rate, and the rest get zero.
    563   EXPECT_EQ(10000u, bitrate_observer_1.last_bitrate_);
    564   EXPECT_EQ(0u, bitrate_observer_2.last_bitrate_);
    565   EXPECT_EQ(0u, bitrate_observer_3.last_bitrate_);
    566 
    567   // Verify it keeps an estimate of at least 10kbps.
    568   bandwidth_observer_->OnReceivedEstimatedBitrate(9000);
    569   EXPECT_EQ(10000u, bitrate_observer_1.last_bitrate_);
    570   EXPECT_EQ(0u, bitrate_observer_2.last_bitrate_);
    571   EXPECT_EQ(0u, bitrate_observer_3.last_bitrate_);
    572 
    573   controller_->RemoveBitrateObserver(&bitrate_observer_1);
    574   controller_->RemoveBitrateObserver(&bitrate_observer_2);
    575   controller_->RemoveBitrateObserver(&bitrate_observer_3);
    576 }
    577 
    578 TEST_F(BitrateControllerTest, ThreeBitrateObserversLowRembEnforceMin) {
    579   TestBitrateObserver bitrate_observer_1;
    580   TestBitrateObserver bitrate_observer_2;
    581   TestBitrateObserver bitrate_observer_3;
    582   controller_->SetBitrateObserver(&bitrate_observer_1, 200000, 100000, 300000);
    583   controller_->SetBitrateObserver(&bitrate_observer_2, 200000, 200000, 300000);
    584   controller_->SetBitrateObserver(&bitrate_observer_3, 200000, 300000, 300000);
    585 
    586   // Low REMB. Verify that all observers still get their respective min bitrate.
    587   bandwidth_observer_->OnReceivedEstimatedBitrate(1000);
    588   EXPECT_EQ(100000u, bitrate_observer_1.last_bitrate_);  // Min cap.
    589   EXPECT_EQ(200000u, bitrate_observer_2.last_bitrate_);  // Min cap.
    590   EXPECT_EQ(300000u, bitrate_observer_3.last_bitrate_);  // Min cap.
    591 
    592   controller_->RemoveBitrateObserver(&bitrate_observer_1);
    593   controller_->RemoveBitrateObserver(&bitrate_observer_2);
    594   controller_->RemoveBitrateObserver(&bitrate_observer_3);
    595 }
    596