tor-browser

rtp_fec_unittest.cc (46198B)

---

/*
*  Copyright (c) 2012 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 <cstddef>
#include <cstdint>
#include <cstring>
#include <list>
#include <memory>
#include <utility>
#include <vector>

#include "absl/algorithm/container.h"
#include "modules/include/module_fec_types.h"
#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/fec_test_helper.h"
#include "modules/rtp_rtcp/source/flexfec_03_header_reader_writer.h"
#include "modules/rtp_rtcp/source/forward_error_correction.h"
#include "modules/rtp_rtcp/source/forward_error_correction_internal.h"
#include "modules/rtp_rtcp/source/ulpfec_header_reader_writer.h"
#include "rtc_base/checks.h"
#include "rtc_base/random.h"
#include "test/gtest.h"

namespace webrtc {

namespace {

// Transport header size in bytes. Assume UDP/IPv4 as a reasonable minimum.
constexpr size_t kTransportOverhead = 28;

constexpr uint32_t kMediaSsrc = 83542;
constexpr uint32_t kFlexfecSsrc = 43245;

constexpr size_t kMaxMediaPackets = 48;

// Deep copies `src` to `dst`, but only keeps every Nth packet.
void DeepCopyEveryNthPacket(const ForwardErrorCorrection::PacketList& src,
                           int n,
                           ForwardErrorCorrection::PacketList* dst) {
 RTC_DCHECK_GT(n, 0);
 int i = 0;
 for (const auto& packet : src) {
   if (i % n == 0) {
     dst->emplace_back(new ForwardErrorCorrection::Packet(*packet));
   }
   ++i;
 }
}

}  // namespace

using ::testing::Types;

template <typename ForwardErrorCorrectionType>
class RtpFecTest : public ::testing::Test {
protected:
 RtpFecTest()
     : random_(0xabcdef123456),
       media_packet_generator_(
           kRtpHeaderSize,  // Minimum packet size.
           IP_PACKET_SIZE - kRtpHeaderSize - kTransportOverhead -
               fec_.MaxPacketOverhead(),  // Maximum packet size.
           kMediaSsrc,
           &random_) {}

 // Construct `received_packets_`: a subset of the media and FEC packets.
 //
 // Media packet "i" is lost if media_loss_mask_[i] = 1, received if
 // media_loss_mask_[i] = 0.
 // FEC packet "i" is lost if fec_loss_mask_[i] = 1, received if
 // fec_loss_mask_[i] = 0.
 void NetworkReceivedPackets(int* media_loss_mask, int* fec_loss_mask);

 // Add packet from `packet_list` to list of received packets, using the
 // `loss_mask`.
 // The `packet_list` may be a media packet list (is_fec = false), or a
 // FEC packet list (is_fec = true).
 template <typename T>
 void ReceivedPackets(const T& packet_list, int* loss_mask, bool is_fec);

 // Check for complete recovery after FEC decoding.
 bool IsRecoveryComplete();

 ForwardErrorCorrectionType fec_;

 Random random_;
 test::fec::MediaPacketGenerator media_packet_generator_;

 ForwardErrorCorrection::PacketList media_packets_;
 std::list<ForwardErrorCorrection::Packet*> generated_fec_packets_;
 std::vector<std::unique_ptr<ForwardErrorCorrection::ReceivedPacket>>
     received_packets_;
 ForwardErrorCorrection::RecoveredPacketList recovered_packets_;

 int media_loss_mask_[kUlpfecMaxMediaPackets];
 int fec_loss_mask_[kUlpfecMaxMediaPackets];
};

template <typename ForwardErrorCorrectionType>
void RtpFecTest<ForwardErrorCorrectionType>::NetworkReceivedPackets(
   int* media_loss_mask,
   int* fec_loss_mask) {
 constexpr bool kFecPacket = true;
 this->received_packets_.clear();
 ReceivedPackets(media_packets_, media_loss_mask, !kFecPacket);
 ReceivedPackets(generated_fec_packets_, fec_loss_mask, kFecPacket);
}

template <typename ForwardErrorCorrectionType>
template <typename PacketListType>
void RtpFecTest<ForwardErrorCorrectionType>::ReceivedPackets(
   const PacketListType& packet_list,
   int* loss_mask,
   bool is_fec) {
 uint16_t fec_seq_num = ForwardErrorCorrectionType::GetFirstFecSeqNum(
     media_packet_generator_.GetNextSeqNum());
 int packet_idx = 0;

 for (const auto& packet : packet_list) {
   if (loss_mask[packet_idx] == 0) {
     std::unique_ptr<ForwardErrorCorrection::ReceivedPacket> received_packet(
         new ForwardErrorCorrection::ReceivedPacket());
     received_packet->pkt = new ForwardErrorCorrection::Packet();
     received_packet->pkt->data = packet->data;
     received_packet->is_fec = is_fec;
     if (!is_fec) {
       received_packet->ssrc = kMediaSsrc;
       // For media packets, the sequence number is obtained from the
       // RTP header as written by MediaPacketGenerator::ConstructMediaPackets.
       received_packet->seq_num =
           ByteReader<uint16_t>::ReadBigEndian(packet->data.data() + 2);
     } else {
       received_packet->ssrc = ForwardErrorCorrectionType::kFecSsrc;
       // For FEC packets, we simulate the sequence numbers differently
       // depending on if ULPFEC or FlexFEC is used. See the definition of
       // ForwardErrorCorrectionType::GetFirstFecSeqNum.
       received_packet->seq_num = fec_seq_num;
     }
     received_packets_.push_back(std::move(received_packet));
   }
   packet_idx++;
   // Sequence number of FEC packets are defined as increment by 1 from
   // last media packet in frame.
   if (is_fec)
     fec_seq_num++;
 }
}

template <typename ForwardErrorCorrectionType>
bool RtpFecTest<ForwardErrorCorrectionType>::IsRecoveryComplete() {
 // We must have equally many recovered packets as original packets and all
 // recovered packets must be identical to the corresponding original packets.
 return absl::c_equal(
     media_packets_, recovered_packets_,
     [](const std::unique_ptr<ForwardErrorCorrection::Packet>& media_packet,
        const std::unique_ptr<ForwardErrorCorrection::RecoveredPacket>&
            recovered_packet) {
       if (media_packet->data.size() != recovered_packet->pkt->data.size()) {
         return false;
       }
       if (memcmp(media_packet->data.cdata(),
                  recovered_packet->pkt->data.cdata(),
                  media_packet->data.size()) != 0) {
         return false;
       }
       return true;
     });
}

// Define gTest typed test to loop over both ULPFEC and FlexFEC.
// Since the tests now are parameterized, we need to access
// member variables using `this`, thereby enforcing runtime
// resolution.

class FlexfecForwardErrorCorrection : public ForwardErrorCorrection {
public:
 static constexpr uint32_t kFecSsrc = kFlexfecSsrc;

 FlexfecForwardErrorCorrection()
     : ForwardErrorCorrection(
           std::unique_ptr<FecHeaderReader>(new Flexfec03HeaderReader()),
           std::unique_ptr<FecHeaderWriter>(new Flexfec03HeaderWriter()),
           kFecSsrc,
           kMediaSsrc) {}

 // For FlexFEC we let the FEC packet sequence numbers be independent of
 // the media packet sequence numbers.
 static uint16_t GetFirstFecSeqNum(uint16_t /* next_media_seq_num */) {
   Random random(0xbe110);
   return random.Rand<uint16_t>();
 }
};

class UlpfecForwardErrorCorrection : public ForwardErrorCorrection {
public:
 static constexpr uint32_t kFecSsrc = kMediaSsrc;

 UlpfecForwardErrorCorrection()
     : ForwardErrorCorrection(
           std::unique_ptr<FecHeaderReader>(new UlpfecHeaderReader()),
           std::unique_ptr<FecHeaderWriter>(new UlpfecHeaderWriter()),
           kFecSsrc,
           kMediaSsrc) {}

 // For ULPFEC we assume that the FEC packets are subsequent to the media
 // packets in terms of sequence number.
 static uint16_t GetFirstFecSeqNum(uint16_t next_media_seq_num) {
   return next_media_seq_num;
 }
};

using FecTypes =
   Types<FlexfecForwardErrorCorrection, UlpfecForwardErrorCorrection>;
TYPED_TEST_SUITE(RtpFecTest, FecTypes);

TYPED_TEST(RtpFecTest, WillProtectMediaPacketsWithLargeSequenceNumberGap) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 2;
 constexpr uint8_t kProtectionFactor = 127;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 // Create |kMaxMediaPackets - 1| sequence number difference.
 ByteWriter<uint16_t>::WriteBigEndian(
     this->media_packets_.front()->data.MutableData() + 2, 1);
 ByteWriter<uint16_t>::WriteBigEndian(
     this->media_packets_.back()->data.MutableData() + 2, kMaxMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));
 EXPECT_EQ(1u, this->generated_fec_packets_.size());
}

TYPED_TEST(RtpFecTest,
          WillNotProtectMediaPacketsWithTooLargeSequenceNumberGap) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 2;
 constexpr uint8_t kProtectionFactor = 127;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 // Create `kMaxMediaPackets` sequence number difference.
 ByteWriter<uint16_t>::WriteBigEndian(
     this->media_packets_.front()->data.MutableData() + 2, 1);
 ByteWriter<uint16_t>::WriteBigEndian(
     this->media_packets_.back()->data.MutableData() + 2,
     kMaxMediaPackets + 1);

 EXPECT_EQ(
     -1, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                              kNumImportantPackets, kUseUnequalProtection,
                              kFecMaskBursty, &this->generated_fec_packets_));
 EXPECT_TRUE(this->generated_fec_packets_.empty());
}

TYPED_TEST(RtpFecTest, FecRecoveryNoLoss) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 60;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // No packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // No packets lost, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryWithLoss) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 60;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // 1 media packet lost
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // One packet lost, one FEC packet, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 2 media packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // 2 packets lost, one FEC packet, cannot get complete recovery.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

// Verify that we don't use an old FEC packet for FEC decoding.
TYPED_TEST(RtpFecTest, NoFecRecoveryWithOldFecPacket) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 20;

 // Two frames: first frame (old) with two media packets and 1 FEC packet.
 // Third frame (new) with 3 media packets, and no FEC packets.
 //
 //  #0(media) #1(media) #2(FEC)              ----Frame 1-----
 //  #32767(media) 32768(media) 32769(media)  ----Frame 2-----
 //  #65535(media) #0(media) #1(media).       ----Frame 3-----
 // If we lose either packet 0 or 1 of third frame, FEC decoding should not
 // try to decode using "old" FEC packet #2.

 // Construct media packets for first frame, starting at sequence number 0.
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(2, 0);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));
 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());
 // Add FEC packet (seq#2) of this first frame to received list (i.e., assume
 // the two media packet were lost).
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->ReceivedPackets(this->generated_fec_packets_, this->fec_loss_mask_,
                       true);

 // Construct media packets for second frame, with sequence number wrap.
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 32767);

 // Expect 3 media packets for this frame.
 EXPECT_EQ(3u, this->media_packets_.size());

 // No packets lost
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);

 // Construct media packets for third frame, with sequence number wrap.
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 65535);

 // Expect 3 media packets for this frame.
 EXPECT_EQ(3u, this->media_packets_.size());

 // Second media packet lost (seq#0).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 this->media_loss_mask_[1] = 1;
 // Add packets #65535, and #1 to received list.
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect that no decoding is done to get missing packet (seq#0) of third
 // frame, using old FEC packet (seq#2) from first (old) frame. So number of
 // recovered packets is 5 (0 from first frame, three from second frame, and 2
 // for the third frame, with no packets recovered via FEC).
 EXPECT_EQ(5u, this->recovered_packets_.size());
 EXPECT_TRUE(this->recovered_packets_.size() != this->media_packets_.size());
}

// Verify we can still recover frame if sequence number wrap occurs within
// the frame and FEC packet following wrap is received after media packets.
TYPED_TEST(RtpFecTest, FecRecoveryWithSeqNumGapOneFrameRecovery) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 20;

 // One frame, with sequence number wrap in media packets.
 //         -----Frame 1----
 //  #65534(media) #65535(media) #0(media) #1(FEC).
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 65534);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // Lose one media packet (seq# 65535).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);
 // Add FEC packet to received list following the media packets.
 this->ReceivedPackets(this->generated_fec_packets_, this->fec_loss_mask_,
                       true);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect 3 media packets in recovered list, and complete recovery.
 // Wrap-around won't remove FEC packet, as it follows the wrap.
 EXPECT_EQ(3u, this->recovered_packets_.size());
 EXPECT_TRUE(this->IsRecoveryComplete());
}

// Sequence number wrap occurs within the ULPFEC packets for the frame.
// Same problem will occur if wrap is within media packets but ULPFEC packet is
// received before the media packets. This may be improved if timing information
// is used to detect old ULPFEC packets.

// TODO(nisse): There's some logic to discard ULPFEC packets at wrap-around,
// however, that is not actually exercised by this test: When the first FEC
// packet is processed, it results in full recovery of one media packet and the
// FEC packet is forgotten. And then the wraparound isn't noticed when the next
// FEC packet is received. We should fix wraparound handling, which currently
// appears broken, and then figure out how to test it properly.
using RtpFecTestUlpfecOnly = RtpFecTest<UlpfecForwardErrorCorrection>;
TEST_F(RtpFecTestUlpfecOnly, FecRecoveryWithSeqNumGapOneFrameRecovery) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 200;

 // 1 frame: 3 media packets and 2 FEC packets.
 // Sequence number wrap in FEC packets.
 //           -----Frame 1----
 // #65532(media) #65533(media) #65534(media) #65535(FEC) #0(FEC).
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 65532);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 2 FEC packets.
 EXPECT_EQ(2u, this->generated_fec_packets_.size());

 // Lose the last two media packets (seq# 65533, 65534).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);
 this->ReceivedPackets(this->generated_fec_packets_, this->fec_loss_mask_,
                       true);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // The two FEC packets are received and should allow for complete recovery,
 // but because of the wrap the first FEC packet will be discarded, and only
 // one media packet is recoverable. So expect 2 media packets on recovered
 // list and no complete recovery.
 EXPECT_EQ(3u, this->recovered_packets_.size());
 EXPECT_EQ(this->recovered_packets_.size(), this->media_packets_.size());
 EXPECT_TRUE(this->IsRecoveryComplete());
}

// TODO(brandtr): This test mimics the one above, ensuring that the recovery
// strategy of FlexFEC matches the recovery strategy of ULPFEC. Since FlexFEC
// does not share the sequence number space with the media, however, having a
// matching recovery strategy may be suboptimal. Study this further.
// TODO(nisse): In this test, recovery based on the first FEC packet fails with
// the log message "The recovered packet had a length larger than a typical IP
// packet, and is thus dropped." This is probably not intended, and needs
// investigation.
using RtpFecTestFlexfecOnly = RtpFecTest<FlexfecForwardErrorCorrection>;
TEST_F(RtpFecTestFlexfecOnly, FecRecoveryWithSeqNumGapOneFrameNoRecovery) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 200;

 // 1 frame: 3 media packets and 2 FEC packets.
 // Sequence number wrap in FEC packets.
 //           -----Frame 1----
 // #65532(media) #65533(media) #65534(media) #65535(FEC) #0(FEC).
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 65532);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 2 FEC packets.
 EXPECT_EQ(2u, this->generated_fec_packets_.size());

 // Overwrite the sequence numbers generated by ConstructMediaPackets,
 // to make sure that we do have a wrap.
 auto it = this->generated_fec_packets_.begin();
 ByteWriter<uint16_t>::WriteBigEndian(&(*it)->data.MutableData()[2], 65535);
 ++it;
 ByteWriter<uint16_t>::WriteBigEndian(&(*it)->data.MutableData()[2], 0);

 // Lose the last two media packets (seq# 65533, 65534).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);
 this->ReceivedPackets(this->generated_fec_packets_, this->fec_loss_mask_,
                       true);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // The two FEC packets are received and should allow for complete recovery,
 // but because of the wrap the first FEC packet will be discarded, and only
 // one media packet is recoverable. So expect 2 media packets on recovered
 // list and no complete recovery.
 EXPECT_EQ(2u, this->recovered_packets_.size());
 EXPECT_TRUE(this->recovered_packets_.size() != this->media_packets_.size());
 EXPECT_FALSE(this->IsRecoveryComplete());
}

// Verify we can still recover frame if media packets are reordered.
TYPED_TEST(RtpFecTest, FecRecoveryWithMediaOutOfOrder) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 20;

 // One frame: 3 media packets, 1 FEC packet.
 //         -----Frame 1----
 //  #0(media) #1(media) #2(media) #3(FEC).
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 0);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // Lose one media packet (seq# 1).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 // Reorder received media packets.
 auto it0 = this->received_packets_.begin();
 auto it1 = this->received_packets_.begin();
 it1++;
 std::swap(*it0, *it1);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect 3 media packets in recovered list, and complete recovery.
 EXPECT_EQ(3u, this->recovered_packets_.size());
 EXPECT_TRUE(this->IsRecoveryComplete());
}

// Verify we can still recover frame if FEC is received before media packets.
TYPED_TEST(RtpFecTest, FecRecoveryWithFecOutOfOrder) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr uint8_t kProtectionFactor = 20;

 // One frame: 3 media packets, 1 FEC packet.
 //         -----Frame 1----
 //  #0(media) #1(media) #2(media) #3(FEC).
 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(3, 0);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // Lose one media packet (seq# 1).
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 // Add FEC packet to received list before the media packets.
 this->ReceivedPackets(this->generated_fec_packets_, this->fec_loss_mask_,
                       true);
 // Add media packets to received list.
 this->ReceivedPackets(this->media_packets_, this->media_loss_mask_, false);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect 3 media packets in recovered list, and complete recovery.
 EXPECT_EQ(3u, this->recovered_packets_.size());
 EXPECT_TRUE(this->IsRecoveryComplete());
}

// Test 50% protection with random mask type: Two cases are considered:
// a 50% non-consecutive loss which can be fully recovered, and a 50%
// consecutive loss which cannot be fully recovered.
TYPED_TEST(RtpFecTest, FecRecoveryWithLoss50percRandomMask) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 255;

 // Packet Mask for (4,4,0) code, from random mask table.
 // (kNumMediaPackets = 4; num_fec_packets = 4, kNumImportantPackets = 0)

 //         media#0   media#1  media#2    media#3
 // fec#0:    1          1        0          0
 // fec#1:    1          0        1          0
 // fec#2:    0          0        1          1
 // fec#3:    0          1        0          1
 //

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskRandom, &this->generated_fec_packets_));

 // Expect 4 FEC packets.
 EXPECT_EQ(4u, this->generated_fec_packets_.size());

 // 4 packets lost: 3 media packets (0, 2, 3), and one FEC packet (0) lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->fec_loss_mask_[0] = 1;
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // With media packet#1 and FEC packets #1, #2, #3, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 4 consecutive packets lost: media packets 0, 1, 2, 3.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Cannot get complete recovery for this loss configuration with random mask.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

// Test 50% protection with bursty type: Three cases are considered:
// two 50% consecutive losses which can be fully recovered, and one
// non-consecutive which cannot be fully recovered.
TYPED_TEST(RtpFecTest, FecRecoveryWithLoss50percBurstyMask) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 255;

 // Packet Mask for (4,4,0) code, from bursty mask table.
 // (kNumMediaPackets = 4; num_fec_packets = 4, kNumImportantPackets = 0)

 //         media#0   media#1  media#2    media#3
 // fec#0:    1          0        0          0
 // fec#1:    1          1        0          0
 // fec#2:    0          1        1          0
 // fec#3:    0          0        1          1
 //

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 4 FEC packets.
 EXPECT_EQ(4u, this->generated_fec_packets_.size());

 // 4 consecutive packets lost: media packets 0,1,2,3.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect complete recovery for consecutive packet loss <= 50%.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 4 consecutive packets lost: media packets 1,2, 3, and FEC packet 0.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->fec_loss_mask_[0] = 1;
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Expect complete recovery for consecutive packet loss <= 50%.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 4 packets lost (non-consecutive loss): media packets 0, 3, and FEC# 0, 3.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->fec_loss_mask_[0] = 1;
 this->fec_loss_mask_[3] = 1;
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Cannot get complete recovery for this loss configuration.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryNoLossUep) {
 constexpr int kNumImportantPackets = 2;
 constexpr bool kUseUnequalProtection = true;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 60;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // No packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // No packets lost, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryWithLossUep) {
 constexpr int kNumImportantPackets = 2;
 constexpr bool kUseUnequalProtection = true;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 60;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // 1 media packet lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // One packet lost, one FEC packet, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 2 media packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // 2 packets lost, one FEC packet, cannot get complete recovery.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

// Test 50% protection with random mask type for UEP on.
TYPED_TEST(RtpFecTest, FecRecoveryWithLoss50percUepRandomMask) {
 constexpr int kNumImportantPackets = 1;
 constexpr bool kUseUnequalProtection = true;
 constexpr int kNumMediaPackets = 4;
 constexpr uint8_t kProtectionFactor = 255;

 // Packet Mask for (4,4,1) code, from random mask table.
 // (kNumMediaPackets = 4; num_fec_packets = 4, kNumImportantPackets = 1)

 //         media#0   media#1  media#2    media#3
 // fec#0:    1          0        0          0
 // fec#1:    1          1        0          0
 // fec#2:    1          0        1          1
 // fec#3:    0          1        1          0
 //

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(this->media_packets_, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskRandom, &this->generated_fec_packets_));

 // Expect 4 FEC packets.
 EXPECT_EQ(4u, this->generated_fec_packets_.size());

 // 4 packets lost: 3 media packets and FEC packet#1 lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->fec_loss_mask_[1] = 1;
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // With media packet#3 and FEC packets #0, #1, #3, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 5 packets lost: 4 media packets and one FEC packet#2 lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->fec_loss_mask_[2] = 1;
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[1] = 1;
 this->media_loss_mask_[2] = 1;
 this->media_loss_mask_[3] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Cannot get complete recovery for this loss configuration.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryNonConsecutivePackets) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 5;
 constexpr uint8_t kProtectionFactor = 60;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 // Create a new temporary packet list for generating FEC packets.
 // This list should have every other packet removed.
 ForwardErrorCorrection::PacketList protected_media_packets;
 DeepCopyEveryNthPacket(this->media_packets_, 2, &protected_media_packets);

 EXPECT_EQ(
     0, this->fec_.EncodeFec(protected_media_packets, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 1 FEC packet.
 EXPECT_EQ(1u, this->generated_fec_packets_.size());

 // 1 protected media packet lost
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[2] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // One packet lost, one FEC packet, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // Unprotected packet lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Unprotected packet lost. Recovery not possible.
 EXPECT_FALSE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 2 media packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[0] = 1;
 this->media_loss_mask_[2] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // 2 protected packets lost, one FEC packet, cannot get complete recovery.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryNonConsecutivePacketsExtension) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 21;
 uint8_t kProtectionFactor = 127;

 this->media_packets_ =
     this->media_packet_generator_.ConstructMediaPackets(kNumMediaPackets);

 // Create a new temporary packet list for generating FEC packets.
 // This list should have every other packet removed.
 ForwardErrorCorrection::PacketList protected_media_packets;
 DeepCopyEveryNthPacket(this->media_packets_, 2, &protected_media_packets);

 // Zero column insertion will have to extend the size of the packet
 // mask since the number of actual packets are 21, while the number
 // of protected packets are 11.
 EXPECT_EQ(
     0, this->fec_.EncodeFec(protected_media_packets, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 5 FEC packet.
 EXPECT_EQ(5u, this->generated_fec_packets_.size());

 // Last protected media packet lost
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // One packet lost, one FEC packet, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // Last unprotected packet lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 2] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Unprotected packet lost. Recovery not possible.
 EXPECT_FALSE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 6 media packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 11] = 1;
 this->media_loss_mask_[kNumMediaPackets - 9] = 1;
 this->media_loss_mask_[kNumMediaPackets - 7] = 1;
 this->media_loss_mask_[kNumMediaPackets - 5] = 1;
 this->media_loss_mask_[kNumMediaPackets - 3] = 1;
 this->media_loss_mask_[kNumMediaPackets - 1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // 5 protected packets lost, one FEC packet, cannot get complete recovery.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

TYPED_TEST(RtpFecTest, FecRecoveryNonConsecutivePacketsWrap) {
 constexpr int kNumImportantPackets = 0;
 constexpr bool kUseUnequalProtection = false;
 constexpr int kNumMediaPackets = 21;
 uint8_t kProtectionFactor = 127;

 this->media_packets_ = this->media_packet_generator_.ConstructMediaPackets(
     kNumMediaPackets, 0xFFFF - 5);

 // Create a new temporary packet list for generating FEC packets.
 // This list should have every other packet removed.
 ForwardErrorCorrection::PacketList protected_media_packets;
 DeepCopyEveryNthPacket(this->media_packets_, 2, &protected_media_packets);

 // Zero column insertion will have to extend the size of the packet
 // mask since the number of actual packets are 21, while the number
 // of protected packets are 11.
 EXPECT_EQ(
     0, this->fec_.EncodeFec(protected_media_packets, kProtectionFactor,
                             kNumImportantPackets, kUseUnequalProtection,
                             kFecMaskBursty, &this->generated_fec_packets_));

 // Expect 5 FEC packet.
 EXPECT_EQ(5u, this->generated_fec_packets_.size());

 // Last protected media packet lost
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // One packet lost, one FEC packet, expect complete recovery.
 EXPECT_TRUE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // Last unprotected packet lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 2] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // Unprotected packet lost. Recovery not possible.
 EXPECT_FALSE(this->IsRecoveryComplete());
 this->recovered_packets_.clear();

 // 6 media packets lost.
 memset(this->media_loss_mask_, 0, sizeof(this->media_loss_mask_));
 memset(this->fec_loss_mask_, 0, sizeof(this->fec_loss_mask_));
 this->media_loss_mask_[kNumMediaPackets - 11] = 1;
 this->media_loss_mask_[kNumMediaPackets - 9] = 1;
 this->media_loss_mask_[kNumMediaPackets - 7] = 1;
 this->media_loss_mask_[kNumMediaPackets - 5] = 1;
 this->media_loss_mask_[kNumMediaPackets - 3] = 1;
 this->media_loss_mask_[kNumMediaPackets - 1] = 1;
 this->NetworkReceivedPackets(this->media_loss_mask_, this->fec_loss_mask_);

 for (const auto& received_packet : this->received_packets_) {
   this->fec_.DecodeFec(*received_packet, &this->recovered_packets_);
 }

 // 5 protected packets lost, one FEC packet, cannot get complete recovery.
 EXPECT_FALSE(this->IsRecoveryComplete());
}

}  // namespace webrtc