modules/audio_coding/neteq/nack_tracker_unittest.cc - src.git - Git at Google

 /*
  *  Copyright (c) 2013 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 "modules/audio_coding/neteq/nack_tracker.h"

 #include <stdint.h>

 #include <algorithm>
 #include <memory>

 #include "modules/audio_coding/include/audio_coding_module_typedefs.h"
 #include "test/field_trial.h"
 #include "test/gtest.h"

 namespace webrtc {
 namespace {

 const int kSampleRateHz = 16000;
 const int kPacketSizeMs = 30;
 const uint32_t kTimestampIncrement = 480;  // 30 ms.
 const int64_t kShortRoundTripTimeMs = 1;

 bool IsNackListCorrect(const std::vector<uint16_t>& nack_list,
                        const uint16_t* lost_sequence_numbers,
                        size_t num_lost_packets) {
   if (nack_list.size() != num_lost_packets)
     return false;

   if (num_lost_packets == 0)
     return true;

   for (size_t k = 0; k < nack_list.size(); ++k) {
     int seq_num = nack_list[k];
     bool seq_num_matched = false;
     for (size_t n = 0; n < num_lost_packets; ++n) {
       if (seq_num == lost_sequence_numbers[n]) {
         seq_num_matched = true;
         break;
       }
     }
     if (!seq_num_matched)
       return false;
   }
   return true;
 }

 }  // namespace

 TEST(NackTrackerTest, EmptyListWhenNoPacketLoss) {
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);

   int seq_num = 1;
   uint32_t timestamp = 0;

   std::vector<uint16_t> nack_list;
   for (int n = 0; n < 100; n++) {
     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     seq_num++;
     timestamp += kTimestampIncrement;
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(nack_list.empty());
   }
 }

 TEST(NackTrackerTest, LatePacketsMovedToNackThenNackListDoesNotChange) {
   const uint16_t kSequenceNumberLostPackets[] = {2, 3, 4, 5, 6, 7, 8, 9};
   static const int kNumAllLostPackets = sizeof(kSequenceNumberLostPackets) /
                                         sizeof(kSequenceNumberLostPackets[0]);

   for (int k = 0; k < 2; k++) {  // Two iteration with/without wrap around.
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);

     uint16_t sequence_num_lost_packets[kNumAllLostPackets];
     for (int n = 0; n < kNumAllLostPackets; n++) {
       sequence_num_lost_packets[n] =
           kSequenceNumberLostPackets[n] +
           k * 65531;  // Have wrap around in sequence numbers for |k == 1|.
     }
     uint16_t seq_num = sequence_num_lost_packets[0] - 1;

     uint32_t timestamp = 0;
     std::vector<uint16_t> nack_list;

     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(nack_list.empty());

     seq_num = sequence_num_lost_packets[kNumAllLostPackets - 1] + 1;
     timestamp += kTimestampIncrement * (kNumAllLostPackets + 1);
     int num_lost_packets = std::max(0, kNumAllLostPackets);

     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(IsNackListCorrect(nack_list, sequence_num_lost_packets,
                                   num_lost_packets));
     seq_num++;
     timestamp += kTimestampIncrement;
     num_lost_packets++;

     for (int n = 0; n < 100; ++n) {
       nack.UpdateLastReceivedPacket(seq_num, timestamp);
       nack_list = nack.GetNackList(kShortRoundTripTimeMs);
       EXPECT_TRUE(IsNackListCorrect(nack_list, sequence_num_lost_packets,
                                     kNumAllLostPackets));
       seq_num++;
       timestamp += kTimestampIncrement;
     }
   }
 }

 TEST(NackTrackerTest, ArrivedPacketsAreRemovedFromNackList) {
   const uint16_t kSequenceNumberLostPackets[] = {2, 3, 4, 5, 6, 7, 8, 9};
   static const int kNumAllLostPackets = sizeof(kSequenceNumberLostPackets) /
                                         sizeof(kSequenceNumberLostPackets[0]);

   for (int k = 0; k < 2; ++k) {  // Two iteration with/without wrap around.
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);

     uint16_t sequence_num_lost_packets[kNumAllLostPackets];
     for (int n = 0; n < kNumAllLostPackets; ++n) {
       sequence_num_lost_packets[n] = kSequenceNumberLostPackets[n] +
                                      k * 65531;  // Wrap around for |k == 1|.
     }

     uint16_t seq_num = sequence_num_lost_packets[0] - 1;
     uint32_t timestamp = 0;

     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(nack_list.empty());

     size_t index_retransmitted_rtp = 0;
     uint32_t timestamp_retransmitted_rtp = timestamp + kTimestampIncrement;

     seq_num = sequence_num_lost_packets[kNumAllLostPackets - 1] + 1;
     timestamp += kTimestampIncrement * (kNumAllLostPackets + 1);
     size_t num_lost_packets = kNumAllLostPackets;
     for (int n = 0; n < kNumAllLostPackets; ++n) {
       // Number of lost packets does not change for the first
       // |kNackThreshold + 1| packets, one is added to the list and one is
       // removed. Thereafter, the list shrinks every iteration.
       if (n >= 1)
         num_lost_packets--;

       nack.UpdateLastReceivedPacket(seq_num, timestamp);
       nack_list = nack.GetNackList(kShortRoundTripTimeMs);
       EXPECT_TRUE(IsNackListCorrect(
           nack_list, &sequence_num_lost_packets[index_retransmitted_rtp],
           num_lost_packets));
       seq_num++;
       timestamp += kTimestampIncrement;

       // Retransmission of a lost RTP.
       nack.UpdateLastReceivedPacket(
           sequence_num_lost_packets[index_retransmitted_rtp],
           timestamp_retransmitted_rtp);
       index_retransmitted_rtp++;
       timestamp_retransmitted_rtp += kTimestampIncrement;

       nack_list = nack.GetNackList(kShortRoundTripTimeMs);
       EXPECT_TRUE(IsNackListCorrect(
           nack_list, &sequence_num_lost_packets[index_retransmitted_rtp],
           num_lost_packets - 1));  // One less lost packet in the list.
     }
     ASSERT_TRUE(nack_list.empty());
   }
 }

 // Assess if estimation of timestamps and time-to-play is correct. Introduce all
 // combinations that timestamps and sequence numbers might have wrap around.
 TEST(NackTrackerTest, EstimateTimestampAndTimeToPlay) {
   const uint16_t kLostPackets[] = {2, 3,  4,  5,  6,  7,  8,
                                    9, 10, 11, 12, 13, 14, 15};
   static const int kNumAllLostPackets =
       sizeof(kLostPackets) / sizeof(kLostPackets[0]);

   for (int k = 0; k < 4; ++k) {
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);

     // Sequence number wrap around if `k` is 2 or 3;
     int seq_num_offset = (k < 2) ? 0 : 65531;

     // Timestamp wrap around if `k` is 1 or 3.
     uint32_t timestamp_offset =
         (k & 0x1) ? static_cast<uint32_t>(0xffffffff) - 6 : 0;

     uint32_t timestamp_lost_packets[kNumAllLostPackets];
     uint16_t seq_num_lost_packets[kNumAllLostPackets];
     for (int n = 0; n < kNumAllLostPackets; ++n) {
       timestamp_lost_packets[n] =
           timestamp_offset + kLostPackets[n] * kTimestampIncrement;
       seq_num_lost_packets[n] = seq_num_offset + kLostPackets[n];
     }

     // We and to push two packets before lost burst starts.
     uint16_t seq_num = seq_num_lost_packets[0] - 2;
     uint32_t timestamp = timestamp_lost_packets[0] - 2 * kTimestampIncrement;

     const uint16_t first_seq_num = seq_num;
     const uint32_t first_timestamp = timestamp;

     // Two consecutive packets to have a correct estimate of timestamp increase.
     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     seq_num++;
     timestamp += kTimestampIncrement;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);

     // A packet after the last one which is supposed to be lost.
     seq_num = seq_num_lost_packets[kNumAllLostPackets - 1] + 1;
     timestamp =
         timestamp_lost_packets[kNumAllLostPackets - 1] + kTimestampIncrement;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);

     NackTracker::NackList nack_list = nack.GetNackList();
     EXPECT_EQ(static_cast<size_t>(kNumAllLostPackets), nack_list.size());

     // Pretend the first packet is decoded.
     nack.UpdateLastDecodedPacket(first_seq_num, first_timestamp);
     nack_list = nack.GetNackList();

     NackTracker::NackList::iterator it = nack_list.begin();
     while (it != nack_list.end()) {
       seq_num = it->first - seq_num_offset;
       int index = seq_num - kLostPackets[0];
       EXPECT_EQ(timestamp_lost_packets[index], it->second.estimated_timestamp);
       EXPECT_EQ((index + 2) * kPacketSizeMs, it->second.time_to_play_ms);
       ++it;
     }
   }
 }

 TEST(NackTrackerTest,
      MissingPacketsPriorToLastDecodedRtpShouldNotBeInNackList) {
   for (int m = 0; m < 2; ++m) {
     uint16_t seq_num_offset = (m == 0) ? 0 : 65531;  // Wrap around if `m` is 1.
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);

     // Two consecutive packets to have a correct estimate of timestamp increase.
     uint16_t seq_num = 0;
     nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
                                   seq_num * kTimestampIncrement);
     seq_num++;
     nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
                                   seq_num * kTimestampIncrement);

     // Skip 10 packets (larger than NACK threshold).
     const int kNumLostPackets = 10;
     seq_num += kNumLostPackets + 1;
     nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
                                   seq_num * kTimestampIncrement);

     const size_t kExpectedListSize = kNumLostPackets;
     std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_EQ(kExpectedListSize, nack_list.size());

     for (int k = 0; k < 2; ++k) {
       // Decoding of the first and the second arrived packets.
       for (int n = 0; n < kPacketSizeMs / 10; ++n) {
         nack.UpdateLastDecodedPacket(seq_num_offset + k,
                                      k * kTimestampIncrement);
         nack_list = nack.GetNackList(kShortRoundTripTimeMs);
         EXPECT_EQ(kExpectedListSize, nack_list.size());
       }
     }

     // Decoding of the last received packet.
     nack.UpdateLastDecodedPacket(seq_num + seq_num_offset,
                                  seq_num * kTimestampIncrement);
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(nack_list.empty());

     // Make sure list of late packets is also empty. To check that, push few
     // packets, if the late list is not empty its content will pop up in NACK
     // list.
     for (int n = 0; n < 10; ++n) {
       seq_num++;
       nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
                                     seq_num * kTimestampIncrement);
       nack_list = nack.GetNackList(kShortRoundTripTimeMs);
       EXPECT_TRUE(nack_list.empty());
     }
   }
 }

 TEST(NackTrackerTest, Reset) {
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);

   // Two consecutive packets to have a correct estimate of timestamp increase.
   uint16_t seq_num = 0;
   nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);
   seq_num++;
   nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);

   // Skip 10 packets (larger than NACK threshold).
   const int kNumLostPackets = 10;
   seq_num += kNumLostPackets + 1;
   nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);

   const size_t kExpectedListSize = kNumLostPackets;
   std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
   EXPECT_EQ(kExpectedListSize, nack_list.size());

   nack.Reset();
   nack_list = nack.GetNackList(kShortRoundTripTimeMs);
   EXPECT_TRUE(nack_list.empty());
 }

 TEST(NackTrackerTest, ListSizeAppliedFromBeginning) {
   const size_t kNackListSize = 10;
   for (int m = 0; m < 2; ++m) {
     uint16_t seq_num_offset = (m == 0) ? 0 : 65525;  // Wrap around if `m` is 1.
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);
     nack.SetMaxNackListSize(kNackListSize);

     uint16_t seq_num = seq_num_offset;
     uint32_t timestamp = 0x12345678;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);

     // Packet lost more than NACK-list size limit.
     uint16_t num_lost_packets = kNackListSize + 5;

     seq_num += num_lost_packets + 1;
     timestamp += (num_lost_packets + 1) * kTimestampIncrement;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);

     std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_EQ(kNackListSize, nack_list.size());
   }
 }

 TEST(NackTrackerTest, ChangeOfListSizeAppliedAndOldElementsRemoved) {
   const size_t kNackListSize = 10;
   for (int m = 0; m < 2; ++m) {
     uint16_t seq_num_offset = (m == 0) ? 0 : 65525;  // Wrap around if `m` is 1.
     NackTracker nack;
     nack.UpdateSampleRate(kSampleRateHz);

     uint16_t seq_num = seq_num_offset;
     uint32_t timestamp = 0x87654321;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);

     // Packet lost more than NACK-list size limit.
     uint16_t num_lost_packets = kNackListSize + 5;

     std::unique_ptr<uint16_t[]> seq_num_lost(new uint16_t[num_lost_packets]);
     for (int n = 0; n < num_lost_packets; ++n) {
       seq_num_lost[n] = ++seq_num;
     }

     ++seq_num;
     timestamp += (num_lost_packets + 1) * kTimestampIncrement;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     size_t expected_size = num_lost_packets;

     std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_EQ(expected_size, nack_list.size());

     nack.SetMaxNackListSize(kNackListSize);
     expected_size = kNackListSize;
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(IsNackListCorrect(
         nack_list, &seq_num_lost[num_lost_packets - kNackListSize],
         expected_size));

     // NACK list should shrink.
     for (size_t n = 1; n < kNackListSize; ++n) {
       ++seq_num;
       timestamp += kTimestampIncrement;
       nack.UpdateLastReceivedPacket(seq_num, timestamp);
       --expected_size;
       nack_list = nack.GetNackList(kShortRoundTripTimeMs);
       EXPECT_TRUE(IsNackListCorrect(
           nack_list, &seq_num_lost[num_lost_packets - kNackListSize + n],
           expected_size));
     }

     // After this packet, NACK list should be empty.
     ++seq_num;
     timestamp += kTimestampIncrement;
     nack.UpdateLastReceivedPacket(seq_num, timestamp);
     nack_list = nack.GetNackList(kShortRoundTripTimeMs);
     EXPECT_TRUE(nack_list.empty());
   }
 }

 TEST(NackTrackerTest, RoudTripTimeIsApplied) {
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);

   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   nack.UpdateLastReceivedPacket(seq_num, timestamp);

   // Packet lost more than NACK-list size limit.
   uint16_t kNumLostPackets = 5;

   seq_num += (1 + kNumLostPackets);
   timestamp += (1 + kNumLostPackets) * kTimestampIncrement;
   nack.UpdateLastReceivedPacket(seq_num, timestamp);

   // Expected time-to-play are:
   // kPacketSizeMs - 10, 2*kPacketSizeMs - 10, 3*kPacketSizeMs - 10, ...
   //
   // sequence number:  1,  2,  3,   4,   5
   // time-to-play:    20, 50, 80, 110, 140
   //
   std::vector<uint16_t> nack_list = nack.GetNackList(100);
   ASSERT_EQ(2u, nack_list.size());
   EXPECT_EQ(4, nack_list[0]);
   EXPECT_EQ(5, nack_list[1]);
 }

 // Set never_nack_multiple_times to true with a field trial and verify that
 // packets are not nacked multiple times.
 TEST(NackTrackerTest, DoNotNackMultipleTimes) {
   test::ScopedFieldTrials field_trials(
       "WebRTC-Audio-NetEqNackTrackerConfig/"
       "packet_loss_forget_factor:0.996,ms_per_loss_percent:20,"
       "never_nack_multiple_times:true/");
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);

   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   nack.UpdateLastReceivedPacket(seq_num, timestamp);

   uint16_t kNumLostPackets = 3;

   seq_num += (1 + kNumLostPackets);
   timestamp += (1 + kNumLostPackets) * kTimestampIncrement;
   nack.UpdateLastReceivedPacket(seq_num, timestamp);

   std::vector<uint16_t> nack_list = nack.GetNackList(10);
   ASSERT_EQ(3u, nack_list.size());
   EXPECT_EQ(1, nack_list[0]);
   EXPECT_EQ(2, nack_list[1]);
   EXPECT_EQ(3, nack_list[2]);
   // When we get the nack list again, it should be empty.
   std::vector<uint16_t> nack_list2 = nack.GetNackList(10);
   EXPECT_TRUE(nack_list2.empty());
 }

 // Test if estimated packet loss rate is correct.
 TEST(NackTrackerTest, PacketLossRateCorrect) {
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);
   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
     if (received) {
       nack.UpdateLastReceivedPacket(seq_num, timestamp);
     }
     seq_num++;
     timestamp += kTimestampIncrement;
   };
   // Add some packets, but every fourth packet is lost.
   for (int i = 0; i < 300; i++) {
     add_packet(true);
     add_packet(true);
     add_packet(true);
     add_packet(false);
   }
   // 1 << 28 is 0.25 in Q30. We expect the packet loss estimate to be within
   // 0.01 of that.
   EXPECT_NEAR(nack.GetPacketLossRateForTest(), 1 << 28, (1 << 30) / 100);
 }

 TEST(NackTrackerTest, DoNotNackAfterDtx) {
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);
   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   nack.UpdateLastReceivedPacket(seq_num, timestamp);
   EXPECT_TRUE(nack.GetNackList(0).empty());
   constexpr int kDtxPeriod = 400;
   nack.UpdateLastReceivedPacket(seq_num + 2,
                                 timestamp + kDtxPeriod * kSampleRateHz / 1000);
   EXPECT_TRUE(nack.GetNackList(0).empty());
 }

 TEST(NackTrackerTest, DoNotNackIfLossRateIsTooHigh) {
   test::ScopedFieldTrials field_trials(
       "WebRTC-Audio-NetEqNackTrackerConfig/max_loss_rate:0.4/");
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);
   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
     if (received) {
       nack.UpdateLastReceivedPacket(seq_num, timestamp);
     }
     seq_num++;
     timestamp += kTimestampIncrement;
   };
   for (int i = 0; i < 500; i++) {
     add_packet(true);
     add_packet(false);
   }
   // Expect 50% loss rate which is higher that the configured maximum 40%.
   EXPECT_NEAR(nack.GetPacketLossRateForTest(), 1 << 29, (1 << 30) / 100);
   EXPECT_TRUE(nack.GetNackList(0).empty());
 }

 TEST(NackTrackerTest, OnlyNackIfRttIsValid) {
   test::ScopedFieldTrials field_trials(
       "WebRTC-Audio-NetEqNackTrackerConfig/require_valid_rtt:true/");
   const int kNackListSize = 200;
   NackTracker nack;
   nack.UpdateSampleRate(kSampleRateHz);
   nack.SetMaxNackListSize(kNackListSize);
   uint16_t seq_num = 0;
   uint32_t timestamp = 0x87654321;
   auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
     if (received) {
       nack.UpdateLastReceivedPacket(seq_num, timestamp);
     }
     seq_num++;
     timestamp += kTimestampIncrement;
   };
   add_packet(true);
   add_packet(false);
   add_packet(true);
   EXPECT_TRUE(nack.GetNackList(0).empty());
   EXPECT_FALSE(nack.GetNackList(10).empty());
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2013 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 "modules/audio_coding/neteq/nack_tracker.h"

	#include <stdint.h>

	#include <algorithm>
	#include <memory>

	#include "modules/audio_coding/include/audio_coding_module_typedefs.h"
	#include "test/field_trial.h"
	#include "test/gtest.h"

	namespace webrtc {
	namespace {

	const int kSampleRateHz = 16000;
	const int kPacketSizeMs = 30;
	const uint32_t kTimestampIncrement = 480; // 30 ms.
	const int64_t kShortRoundTripTimeMs = 1;

	bool IsNackListCorrect(const std::vector<uint16_t>& nack_list,
	const uint16_t* lost_sequence_numbers,
	size_t num_lost_packets) {
	if (nack_list.size() != num_lost_packets)
	return false;

	if (num_lost_packets == 0)
	return true;

	for (size_t k = 0; k < nack_list.size(); ++k) {
	int seq_num = nack_list[k];
	bool seq_num_matched = false;
	for (size_t n = 0; n < num_lost_packets; ++n) {
	if (seq_num == lost_sequence_numbers[n]) {
	seq_num_matched = true;
	break;
	}
	}
	if (!seq_num_matched)
	return false;
	}
	return true;
	}

	} // namespace

	TEST(NackTrackerTest, EmptyListWhenNoPacketLoss) {
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	int seq_num = 1;
	uint32_t timestamp = 0;

	std::vector<uint16_t> nack_list;
	for (int n = 0; n < 100; n++) {
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	seq_num++;
	timestamp += kTimestampIncrement;
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());
	}
	}

	TEST(NackTrackerTest, LatePacketsMovedToNackThenNackListDoesNotChange) {
	const uint16_t kSequenceNumberLostPackets[] = {2, 3, 4, 5, 6, 7, 8, 9};
	static const int kNumAllLostPackets = sizeof(kSequenceNumberLostPackets) /
	sizeof(kSequenceNumberLostPackets[0]);

	for (int k = 0; k < 2; k++) { // Two iteration with/without wrap around.
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	uint16_t sequence_num_lost_packets[kNumAllLostPackets];
	for (int n = 0; n < kNumAllLostPackets; n++) {
	sequence_num_lost_packets[n] =
	kSequenceNumberLostPackets[n] +
	k * 65531; // Have wrap around in sequence numbers for \|k == 1\|.
	}
	uint16_t seq_num = sequence_num_lost_packets[0] - 1;

	uint32_t timestamp = 0;
	std::vector<uint16_t> nack_list;

	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());

	seq_num = sequence_num_lost_packets[kNumAllLostPackets - 1] + 1;
	timestamp += kTimestampIncrement * (kNumAllLostPackets + 1);
	int num_lost_packets = std::max(0, kNumAllLostPackets);

	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(nack_list, sequence_num_lost_packets,
	num_lost_packets));
	seq_num++;
	timestamp += kTimestampIncrement;
	num_lost_packets++;

	for (int n = 0; n < 100; ++n) {
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(nack_list, sequence_num_lost_packets,
	kNumAllLostPackets));
	seq_num++;
	timestamp += kTimestampIncrement;
	}
	}
	}

	TEST(NackTrackerTest, ArrivedPacketsAreRemovedFromNackList) {
	const uint16_t kSequenceNumberLostPackets[] = {2, 3, 4, 5, 6, 7, 8, 9};
	static const int kNumAllLostPackets = sizeof(kSequenceNumberLostPackets) /
	sizeof(kSequenceNumberLostPackets[0]);

	for (int k = 0; k < 2; ++k) { // Two iteration with/without wrap around.
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	uint16_t sequence_num_lost_packets[kNumAllLostPackets];
	for (int n = 0; n < kNumAllLostPackets; ++n) {
	sequence_num_lost_packets[n] = kSequenceNumberLostPackets[n] +
	k * 65531; // Wrap around for \|k == 1\|.
	}

	uint16_t seq_num = sequence_num_lost_packets[0] - 1;
	uint32_t timestamp = 0;

	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());

	size_t index_retransmitted_rtp = 0;
	uint32_t timestamp_retransmitted_rtp = timestamp + kTimestampIncrement;

	seq_num = sequence_num_lost_packets[kNumAllLostPackets - 1] + 1;
	timestamp += kTimestampIncrement * (kNumAllLostPackets + 1);
	size_t num_lost_packets = kNumAllLostPackets;
	for (int n = 0; n < kNumAllLostPackets; ++n) {
	// Number of lost packets does not change for the first
	// \|kNackThreshold + 1\| packets, one is added to the list and one is
	// removed. Thereafter, the list shrinks every iteration.
	if (n >= 1)
	num_lost_packets--;

	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(
	nack_list, &sequence_num_lost_packets[index_retransmitted_rtp],
	num_lost_packets));
	seq_num++;
	timestamp += kTimestampIncrement;

	// Retransmission of a lost RTP.
	nack.UpdateLastReceivedPacket(
	sequence_num_lost_packets[index_retransmitted_rtp],
	timestamp_retransmitted_rtp);
	index_retransmitted_rtp++;
	timestamp_retransmitted_rtp += kTimestampIncrement;

	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(
	nack_list, &sequence_num_lost_packets[index_retransmitted_rtp],
	num_lost_packets - 1)); // One less lost packet in the list.
	}
	ASSERT_TRUE(nack_list.empty());
	}
	}

	// Assess if estimation of timestamps and time-to-play is correct. Introduce all
	// combinations that timestamps and sequence numbers might have wrap around.
	TEST(NackTrackerTest, EstimateTimestampAndTimeToPlay) {
	const uint16_t kLostPackets[] = {2, 3, 4, 5, 6, 7, 8,
	9, 10, 11, 12, 13, 14, 15};
	static const int kNumAllLostPackets =
	sizeof(kLostPackets) / sizeof(kLostPackets[0]);

	for (int k = 0; k < 4; ++k) {
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	// Sequence number wrap around if `k` is 2 or 3;
	int seq_num_offset = (k < 2) ? 0 : 65531;

	// Timestamp wrap around if `k` is 1 or 3.
	uint32_t timestamp_offset =
	(k & 0x1) ? static_cast<uint32_t>(0xffffffff) - 6 : 0;

	uint32_t timestamp_lost_packets[kNumAllLostPackets];
	uint16_t seq_num_lost_packets[kNumAllLostPackets];
	for (int n = 0; n < kNumAllLostPackets; ++n) {
	timestamp_lost_packets[n] =
	timestamp_offset + kLostPackets[n] * kTimestampIncrement;
	seq_num_lost_packets[n] = seq_num_offset + kLostPackets[n];
	}

	// We and to push two packets before lost burst starts.
	uint16_t seq_num = seq_num_lost_packets[0] - 2;
	uint32_t timestamp = timestamp_lost_packets[0] - 2 * kTimestampIncrement;

	const uint16_t first_seq_num = seq_num;
	const uint32_t first_timestamp = timestamp;

	// Two consecutive packets to have a correct estimate of timestamp increase.
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	seq_num++;
	timestamp += kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	// A packet after the last one which is supposed to be lost.
	seq_num = seq_num_lost_packets[kNumAllLostPackets - 1] + 1;
	timestamp =
	timestamp_lost_packets[kNumAllLostPackets - 1] + kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	NackTracker::NackList nack_list = nack.GetNackList();
	EXPECT_EQ(static_cast<size_t>(kNumAllLostPackets), nack_list.size());

	// Pretend the first packet is decoded.
	nack.UpdateLastDecodedPacket(first_seq_num, first_timestamp);
	nack_list = nack.GetNackList();

	NackTracker::NackList::iterator it = nack_list.begin();
	while (it != nack_list.end()) {
	seq_num = it->first - seq_num_offset;
	int index = seq_num - kLostPackets[0];
	EXPECT_EQ(timestamp_lost_packets[index], it->second.estimated_timestamp);
	EXPECT_EQ((index + 2) * kPacketSizeMs, it->second.time_to_play_ms);
	++it;
	}
	}
	}

	TEST(NackTrackerTest,
	MissingPacketsPriorToLastDecodedRtpShouldNotBeInNackList) {
	for (int m = 0; m < 2; ++m) {
	uint16_t seq_num_offset = (m == 0) ? 0 : 65531; // Wrap around if `m` is 1.
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	// Two consecutive packets to have a correct estimate of timestamp increase.
	uint16_t seq_num = 0;
	nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
	seq_num * kTimestampIncrement);
	seq_num++;
	nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
	seq_num * kTimestampIncrement);

	// Skip 10 packets (larger than NACK threshold).
	const int kNumLostPackets = 10;
	seq_num += kNumLostPackets + 1;
	nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
	seq_num * kTimestampIncrement);

	const size_t kExpectedListSize = kNumLostPackets;
	std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_EQ(kExpectedListSize, nack_list.size());

	for (int k = 0; k < 2; ++k) {
	// Decoding of the first and the second arrived packets.
	for (int n = 0; n < kPacketSizeMs / 10; ++n) {
	nack.UpdateLastDecodedPacket(seq_num_offset + k,
	k * kTimestampIncrement);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_EQ(kExpectedListSize, nack_list.size());
	}
	}

	// Decoding of the last received packet.
	nack.UpdateLastDecodedPacket(seq_num + seq_num_offset,
	seq_num * kTimestampIncrement);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());

	// Make sure list of late packets is also empty. To check that, push few
	// packets, if the late list is not empty its content will pop up in NACK
	// list.
	for (int n = 0; n < 10; ++n) {
	seq_num++;
	nack.UpdateLastReceivedPacket(seq_num_offset + seq_num,
	seq_num * kTimestampIncrement);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());
	}
	}
	}

	TEST(NackTrackerTest, Reset) {
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	// Two consecutive packets to have a correct estimate of timestamp increase.
	uint16_t seq_num = 0;
	nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);
	seq_num++;
	nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);

	// Skip 10 packets (larger than NACK threshold).
	const int kNumLostPackets = 10;
	seq_num += kNumLostPackets + 1;
	nack.UpdateLastReceivedPacket(seq_num, seq_num * kTimestampIncrement);

	const size_t kExpectedListSize = kNumLostPackets;
	std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_EQ(kExpectedListSize, nack_list.size());

	nack.Reset();
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());
	}

	TEST(NackTrackerTest, ListSizeAppliedFromBeginning) {
	const size_t kNackListSize = 10;
	for (int m = 0; m < 2; ++m) {
	uint16_t seq_num_offset = (m == 0) ? 0 : 65525; // Wrap around if `m` is 1.
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);

	uint16_t seq_num = seq_num_offset;
	uint32_t timestamp = 0x12345678;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	// Packet lost more than NACK-list size limit.
	uint16_t num_lost_packets = kNackListSize + 5;

	seq_num += num_lost_packets + 1;
	timestamp += (num_lost_packets + 1) * kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_EQ(kNackListSize, nack_list.size());
	}
	}

	TEST(NackTrackerTest, ChangeOfListSizeAppliedAndOldElementsRemoved) {
	const size_t kNackListSize = 10;
	for (int m = 0; m < 2; ++m) {
	uint16_t seq_num_offset = (m == 0) ? 0 : 65525; // Wrap around if `m` is 1.
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);

	uint16_t seq_num = seq_num_offset;
	uint32_t timestamp = 0x87654321;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	// Packet lost more than NACK-list size limit.
	uint16_t num_lost_packets = kNackListSize + 5;

	std::unique_ptr<uint16_t[]> seq_num_lost(new uint16_t[num_lost_packets]);
	for (int n = 0; n < num_lost_packets; ++n) {
	seq_num_lost[n] = ++seq_num;
	}

	++seq_num;
	timestamp += (num_lost_packets + 1) * kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	size_t expected_size = num_lost_packets;

	std::vector<uint16_t> nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_EQ(expected_size, nack_list.size());

	nack.SetMaxNackListSize(kNackListSize);
	expected_size = kNackListSize;
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(
	nack_list, &seq_num_lost[num_lost_packets - kNackListSize],
	expected_size));

	// NACK list should shrink.
	for (size_t n = 1; n < kNackListSize; ++n) {
	++seq_num;
	timestamp += kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	--expected_size;
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(IsNackListCorrect(
	nack_list, &seq_num_lost[num_lost_packets - kNackListSize + n],
	expected_size));
	}

	// After this packet, NACK list should be empty.
	++seq_num;
	timestamp += kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	nack_list = nack.GetNackList(kShortRoundTripTimeMs);
	EXPECT_TRUE(nack_list.empty());
	}
	}

	TEST(NackTrackerTest, RoudTripTimeIsApplied) {
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);

	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	// Packet lost more than NACK-list size limit.
	uint16_t kNumLostPackets = 5;

	seq_num += (1 + kNumLostPackets);
	timestamp += (1 + kNumLostPackets) * kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	// Expected time-to-play are:
	// kPacketSizeMs - 10, 2kPacketSizeMs - 10, 3kPacketSizeMs - 10, ...
	//
	// sequence number: 1, 2, 3, 4, 5
	// time-to-play: 20, 50, 80, 110, 140
	//
	std::vector<uint16_t> nack_list = nack.GetNackList(100);
	ASSERT_EQ(2u, nack_list.size());
	EXPECT_EQ(4, nack_list[0]);
	EXPECT_EQ(5, nack_list[1]);
	}

	// Set never_nack_multiple_times to true with a field trial and verify that
	// packets are not nacked multiple times.
	TEST(NackTrackerTest, DoNotNackMultipleTimes) {
	test::ScopedFieldTrials field_trials(
	"WebRTC-Audio-NetEqNackTrackerConfig/"
	"packet_loss_forget_factor:0.996,ms_per_loss_percent:20,"
	"never_nack_multiple_times:true/");
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);

	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	uint16_t kNumLostPackets = 3;

	seq_num += (1 + kNumLostPackets);
	timestamp += (1 + kNumLostPackets) * kTimestampIncrement;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);

	std::vector<uint16_t> nack_list = nack.GetNackList(10);
	ASSERT_EQ(3u, nack_list.size());
	EXPECT_EQ(1, nack_list[0]);
	EXPECT_EQ(2, nack_list[1]);
	EXPECT_EQ(3, nack_list[2]);
	// When we get the nack list again, it should be empty.
	std::vector<uint16_t> nack_list2 = nack.GetNackList(10);
	EXPECT_TRUE(nack_list2.empty());
	}

	// Test if estimated packet loss rate is correct.
	TEST(NackTrackerTest, PacketLossRateCorrect) {
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);
	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
	if (received) {
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	}
	seq_num++;
	timestamp += kTimestampIncrement;
	};
	// Add some packets, but every fourth packet is lost.
	for (int i = 0; i < 300; i++) {
	add_packet(true);
	add_packet(true);
	add_packet(true);
	add_packet(false);
	}
	// 1 << 28 is 0.25 in Q30. We expect the packet loss estimate to be within
	// 0.01 of that.
	EXPECT_NEAR(nack.GetPacketLossRateForTest(), 1 << 28, (1 << 30) / 100);
	}

	TEST(NackTrackerTest, DoNotNackAfterDtx) {
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);
	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	EXPECT_TRUE(nack.GetNackList(0).empty());
	constexpr int kDtxPeriod = 400;
	nack.UpdateLastReceivedPacket(seq_num + 2,
	timestamp + kDtxPeriod * kSampleRateHz / 1000);
	EXPECT_TRUE(nack.GetNackList(0).empty());
	}

	TEST(NackTrackerTest, DoNotNackIfLossRateIsTooHigh) {
	test::ScopedFieldTrials field_trials(
	"WebRTC-Audio-NetEqNackTrackerConfig/max_loss_rate:0.4/");
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);
	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
	if (received) {
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	}
	seq_num++;
	timestamp += kTimestampIncrement;
	};
	for (int i = 0; i < 500; i++) {
	add_packet(true);
	add_packet(false);
	}
	// Expect 50% loss rate which is higher that the configured maximum 40%.
	EXPECT_NEAR(nack.GetPacketLossRateForTest(), 1 << 29, (1 << 30) / 100);
	EXPECT_TRUE(nack.GetNackList(0).empty());
	}

	TEST(NackTrackerTest, OnlyNackIfRttIsValid) {
	test::ScopedFieldTrials field_trials(
	"WebRTC-Audio-NetEqNackTrackerConfig/require_valid_rtt:true/");
	const int kNackListSize = 200;
	NackTracker nack;
	nack.UpdateSampleRate(kSampleRateHz);
	nack.SetMaxNackListSize(kNackListSize);
	uint16_t seq_num = 0;
	uint32_t timestamp = 0x87654321;
	auto add_packet = [&nack, &seq_num, &timestamp](bool received) {
	if (received) {
	nack.UpdateLastReceivedPacket(seq_num, timestamp);
	}
	seq_num++;
	timestamp += kTimestampIncrement;
	};
	add_packet(true);
	add_packet(false);
	add_packet(true);
	EXPECT_TRUE(nack.GetNackList(0).empty());
	EXPECT_FALSE(nack.GetNackList(10).empty());
	}

	} // namespace webrtc