modules/rtp_rtcp/source/flexfec_sender_unittest.cc - src - Git at Google

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "modules/rtp_rtcp/include/flexfec_sender.h"

 #include <vector>

 #include "api/environment/environment.h"
 #include "api/environment/environment_factory.h"
 #include "api/rtp_parameters.h"
 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "modules/rtp_rtcp/source/fec_test_helper.h"
 #include "modules/rtp_rtcp/source/rtp_header_extensions.h"
 #include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
 #include "modules/rtp_rtcp/source/rtp_sender.h"
 #include "system_wrappers/include/clock.h"
 #include "test/gtest.h"

 namespace webrtc {

 namespace {

 using test::fec::AugmentedPacket;
 using test::fec::AugmentedPacketGenerator;

 constexpr int kFlexfecPayloadType = 123;
 constexpr uint32_t kMediaSsrc = 1234;
 constexpr uint32_t kFlexfecSsrc = 5678;
 const char kNoMid[] = "";
 const std::vector<RtpExtension> kNoRtpHeaderExtensions;
 const std::vector<RtpExtensionSize> kNoRtpHeaderExtensionSizes;
 // Assume a single protected media SSRC.
 constexpr size_t kFlexfecMaxHeaderSize = 32;
 constexpr size_t kPayloadLength = 50;

 constexpr int64_t kInitialSimulatedClockTime = 1;
 // These values are deterministically given by the PRNG, due to our fixed seed.
 // They should be updated if the PRNG implementation changes.
 constexpr uint16_t kDeterministicSequenceNumber = 28732;
 constexpr uint32_t kDeterministicTimestamp = 2305613085;

 // Round up to the nearest size that is a multiple of 4.
 size_t Word32Align(size_t size) {
   uint32_t remainder = size % 4;
   if (remainder != 0)
     return size + 4 - remainder;
   return size;
 }

 std::unique_ptr<RtpPacketToSend> GenerateSingleFlexfecPacket(
     FlexfecSender* sender) {
   // Parameters selected to generate a single FEC packet.
   FecProtectionParams params;
   params.fec_rate = 15;
   params.max_fec_frames = 1;
   params.fec_mask_type = kFecMaskRandom;
   constexpr size_t kNumPackets = 4;

   sender->SetProtectionParameters(params, params);
   AugmentedPacketGenerator packet_generator(kMediaSsrc);
   packet_generator.NewFrame(kNumPackets);
   for (size_t i = 0; i < kNumPackets; ++i) {
     std::unique_ptr<AugmentedPacket> packet =
         packet_generator.NextPacket(i, kPayloadLength);
     RtpPacketToSend rtp_packet(nullptr);  // No header extensions.
     rtp_packet.Parse(packet->data);
     sender->AddPacketAndGenerateFec(rtp_packet);
   }
   std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
       sender->GetFecPackets();
   EXPECT_EQ(1U, fec_packets.size());
   EXPECT_TRUE(sender->GetFecPackets().empty());

   return std::move(fec_packets.front());
 }

 }  // namespace

 TEST(FlexfecSenderTest, Ssrc) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

   EXPECT_EQ(kFlexfecSsrc, sender.FecSsrc());
 }

 TEST(FlexfecSenderTest, NoFecAvailableBeforeMediaAdded) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

   EXPECT_TRUE(sender.GetFecPackets().empty());
 }

 TEST(FlexfecSenderTest, ProtectOneFrameWithOneFecPacket) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
   EXPECT_FALSE(fec_packet->Marker());
   EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
   EXPECT_EQ(kDeterministicSequenceNumber, fec_packet->SequenceNumber());
   EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
   EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
   EXPECT_LE(kPayloadLength, fec_packet->payload_size());
 }

 TEST(FlexfecSenderTest, ProtectTwoFramesWithOneFecPacket) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   // FEC parameters selected to generate a single FEC packet per frame.
   FecProtectionParams params;
   params.fec_rate = 15;
   params.max_fec_frames = 2;
   params.fec_mask_type = kFecMaskRandom;
   constexpr size_t kNumFrames = 2;
   constexpr size_t kNumPacketsPerFrame = 2;
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
   sender.SetProtectionParameters(params, params);

   AugmentedPacketGenerator packet_generator(kMediaSsrc);
   for (size_t i = 0; i < kNumFrames; ++i) {
     packet_generator.NewFrame(kNumPacketsPerFrame);
     for (size_t j = 0; j < kNumPacketsPerFrame; ++j) {
       std::unique_ptr<AugmentedPacket> packet =
           packet_generator.NextPacket(i, kPayloadLength);
       RtpPacketToSend rtp_packet(nullptr);
       rtp_packet.Parse(packet->data);
       sender.AddPacketAndGenerateFec(rtp_packet);
     }
   }
   std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
       sender.GetFecPackets();
   ASSERT_EQ(1U, fec_packets.size());
   EXPECT_TRUE(sender.GetFecPackets().empty());

   RtpPacketToSend* fec_packet = fec_packets.front().get();
   EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
   EXPECT_FALSE(fec_packet->Marker());
   EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
   EXPECT_EQ(kDeterministicSequenceNumber, fec_packet->SequenceNumber());
   EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
   EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
 }

 TEST(FlexfecSenderTest, ProtectTwoFramesWithTwoFecPackets) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   // FEC parameters selected to generate a single FEC packet per frame.
   FecProtectionParams params;
   params.fec_rate = 30;
   params.max_fec_frames = 1;
   params.fec_mask_type = kFecMaskRandom;
   constexpr size_t kNumFrames = 2;
   constexpr size_t kNumPacketsPerFrame = 2;
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
   sender.SetProtectionParameters(params, params);

   AugmentedPacketGenerator packet_generator(kMediaSsrc);
   for (size_t i = 0; i < kNumFrames; ++i) {
     packet_generator.NewFrame(kNumPacketsPerFrame);
     for (size_t j = 0; j < kNumPacketsPerFrame; ++j) {
       std::unique_ptr<AugmentedPacket> packet =
           packet_generator.NextPacket(i, kPayloadLength);
       RtpPacketToSend rtp_packet(nullptr);
       rtp_packet.Parse(packet->data);
       sender.AddPacketAndGenerateFec(rtp_packet);
     }
     std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
         sender.GetFecPackets();
     ASSERT_EQ(1U, fec_packets.size());
     EXPECT_TRUE(sender.GetFecPackets().empty());

     RtpPacketToSend* fec_packet = fec_packets.front().get();
     EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
     EXPECT_FALSE(fec_packet->Marker());
     EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
     EXPECT_EQ(static_cast<uint16_t>(kDeterministicSequenceNumber + i),
               fec_packet->SequenceNumber());
     EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
     EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
   }
 }

 // In the tests, we only consider RTP header extensions that are useful for BWE.
 TEST(FlexfecSenderTest, NoRtpHeaderExtensionsForBweByDefault) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{};
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
                        nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
 }

 TEST(FlexfecSenderTest, RegisterAbsoluteSendTimeRtpHeaderExtension) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kAbsSendTimeUri, 1}};
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
                        nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_TRUE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
 }

 TEST(FlexfecSenderTest, RegisterTransmissionOffsetRtpHeaderExtension) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kTimestampOffsetUri, 1}};
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
                        nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_TRUE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
 }

 TEST(FlexfecSenderTest, RegisterTransportSequenceNumberRtpHeaderExtension) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kTransportSequenceNumberUri, 1}};
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
                        nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_TRUE(fec_packet->HasExtension<TransportSequenceNumber>());
 }

 TEST(FlexfecSenderTest, RegisterAllRtpHeaderExtensionsForBwe) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kAbsSendTimeUri, 1},
       {RtpExtension::kTimestampOffsetUri, 2},
       {RtpExtension::kTransportSequenceNumberUri, 3}};
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
                        nullptr /* rtp_state */);
   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   EXPECT_TRUE(fec_packet->HasExtension<AbsoluteSendTime>());
   EXPECT_TRUE(fec_packet->HasExtension<TransmissionOffset>());
   EXPECT_TRUE(fec_packet->HasExtension<TransportSequenceNumber>());
 }

 TEST(FlexfecSenderTest, MaxPacketOverhead) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

   EXPECT_EQ(kFlexfecMaxHeaderSize, sender.MaxPacketOverhead());
 }

 TEST(FlexfecSenderTest, MaxPacketOverheadWithExtensions) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kAbsSendTimeUri, 1},
       {RtpExtension::kTimestampOffsetUri, 2},
       {RtpExtension::kTransportSequenceNumberUri, 3}};
   const size_t kExtensionHeaderLength = 1;
   const size_t kRtpOneByteHeaderLength = 4;
   const size_t kExtensionsTotalSize =
       Word32Align(kRtpOneByteHeaderLength + kExtensionHeaderLength +
                   AbsoluteSendTime::kValueSizeBytes + kExtensionHeaderLength +
                   TransmissionOffset::kValueSizeBytes + kExtensionHeaderLength +
                   TransportSequenceNumber::kValueSizeBytes);
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kRtpHeaderExtensions,
                        RTPSender::FecExtensionSizes(), nullptr /* rtp_state */);

   EXPECT_EQ(kExtensionsTotalSize + kFlexfecMaxHeaderSize,
             sender.MaxPacketOverhead());
 }

 TEST(FlexfecSenderTest, MidIncludedInPacketsWhenSet) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   const std::vector<RtpExtension> kRtpHeaderExtensions{
       {RtpExtension::kMidUri, 1}};
   const char kMid[] = "mid";
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc, kMid,
                        kRtpHeaderExtensions, RTPSender::FecExtensionSizes(),
                        nullptr /* rtp_state */);

   auto fec_packet = GenerateSingleFlexfecPacket(&sender);

   std::string mid;
   ASSERT_TRUE(fec_packet->GetExtension<RtpMid>(&mid));
   EXPECT_EQ(kMid, mid);
 }

 TEST(FlexfecSenderTest, SetsAndGetsRtpState) {
   SimulatedClock clock(kInitialSimulatedClockTime);
   const Environment env = CreateEnvironment(&clock);
   RtpState initial_rtp_state;
   initial_rtp_state.sequence_number = 100;
   initial_rtp_state.start_timestamp = 200;
   FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
                        kNoMid, kNoRtpHeaderExtensions,
                        kNoRtpHeaderExtensionSizes, &initial_rtp_state);

   auto fec_packet = GenerateSingleFlexfecPacket(&sender);
   EXPECT_EQ(initial_rtp_state.sequence_number, fec_packet->SequenceNumber());
   EXPECT_EQ(initial_rtp_state.start_timestamp, fec_packet->Timestamp());

   clock.AdvanceTimeMilliseconds(1000);
   fec_packet = GenerateSingleFlexfecPacket(&sender);
   EXPECT_EQ(initial_rtp_state.sequence_number + 1,
             fec_packet->SequenceNumber());
   EXPECT_EQ(initial_rtp_state.start_timestamp + 1 * kVideoPayloadTypeFrequency,
             fec_packet->Timestamp());

   RtpState updated_rtp_state = sender.GetRtpState().value();
   EXPECT_EQ(initial_rtp_state.sequence_number + 2,
             updated_rtp_state.sequence_number);
   EXPECT_EQ(initial_rtp_state.start_timestamp,
             updated_rtp_state.start_timestamp);
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "modules/rtp_rtcp/include/flexfec_sender.h"

	#include <vector>

	#include "api/environment/environment.h"
	#include "api/environment/environment_factory.h"
	#include "api/rtp_parameters.h"
	#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
	#include "modules/rtp_rtcp/source/fec_test_helper.h"
	#include "modules/rtp_rtcp/source/rtp_header_extensions.h"
	#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
	#include "modules/rtp_rtcp/source/rtp_sender.h"
	#include "system_wrappers/include/clock.h"
	#include "test/gtest.h"

	namespace webrtc {

	namespace {

	using test::fec::AugmentedPacket;
	using test::fec::AugmentedPacketGenerator;

	constexpr int kFlexfecPayloadType = 123;
	constexpr uint32_t kMediaSsrc = 1234;
	constexpr uint32_t kFlexfecSsrc = 5678;
	const char kNoMid[] = "";
	const std::vector<RtpExtension> kNoRtpHeaderExtensions;
	const std::vector<RtpExtensionSize> kNoRtpHeaderExtensionSizes;
	// Assume a single protected media SSRC.
	constexpr size_t kFlexfecMaxHeaderSize = 32;
	constexpr size_t kPayloadLength = 50;

	constexpr int64_t kInitialSimulatedClockTime = 1;
	// These values are deterministically given by the PRNG, due to our fixed seed.
	// They should be updated if the PRNG implementation changes.
	constexpr uint16_t kDeterministicSequenceNumber = 28732;
	constexpr uint32_t kDeterministicTimestamp = 2305613085;

	// Round up to the nearest size that is a multiple of 4.
	size_t Word32Align(size_t size) {
	uint32_t remainder = size % 4;
	if (remainder != 0)
	return size + 4 - remainder;
	return size;
	}

	std::unique_ptr<RtpPacketToSend> GenerateSingleFlexfecPacket(
	FlexfecSender* sender) {
	// Parameters selected to generate a single FEC packet.
	FecProtectionParams params;
	params.fec_rate = 15;
	params.max_fec_frames = 1;
	params.fec_mask_type = kFecMaskRandom;
	constexpr size_t kNumPackets = 4;

	sender->SetProtectionParameters(params, params);
	AugmentedPacketGenerator packet_generator(kMediaSsrc);
	packet_generator.NewFrame(kNumPackets);
	for (size_t i = 0; i < kNumPackets; ++i) {
	std::unique_ptr<AugmentedPacket> packet =
	packet_generator.NextPacket(i, kPayloadLength);
	RtpPacketToSend rtp_packet(nullptr); // No header extensions.
	rtp_packet.Parse(packet->data);
	sender->AddPacketAndGenerateFec(rtp_packet);
	}
	std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
	sender->GetFecPackets();
	EXPECT_EQ(1U, fec_packets.size());
	EXPECT_TRUE(sender->GetFecPackets().empty());

	return std::move(fec_packets.front());
	}

	} // namespace

	TEST(FlexfecSenderTest, Ssrc) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

	EXPECT_EQ(kFlexfecSsrc, sender.FecSsrc());
	}

	TEST(FlexfecSenderTest, NoFecAvailableBeforeMediaAdded) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

	EXPECT_TRUE(sender.GetFecPackets().empty());
	}

	TEST(FlexfecSenderTest, ProtectOneFrameWithOneFecPacket) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
	EXPECT_FALSE(fec_packet->Marker());
	EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
	EXPECT_EQ(kDeterministicSequenceNumber, fec_packet->SequenceNumber());
	EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
	EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
	EXPECT_LE(kPayloadLength, fec_packet->payload_size());
	}

	TEST(FlexfecSenderTest, ProtectTwoFramesWithOneFecPacket) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	// FEC parameters selected to generate a single FEC packet per frame.
	FecProtectionParams params;
	params.fec_rate = 15;
	params.max_fec_frames = 2;
	params.fec_mask_type = kFecMaskRandom;
	constexpr size_t kNumFrames = 2;
	constexpr size_t kNumPacketsPerFrame = 2;
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
	sender.SetProtectionParameters(params, params);

	AugmentedPacketGenerator packet_generator(kMediaSsrc);
	for (size_t i = 0; i < kNumFrames; ++i) {
	packet_generator.NewFrame(kNumPacketsPerFrame);
	for (size_t j = 0; j < kNumPacketsPerFrame; ++j) {
	std::unique_ptr<AugmentedPacket> packet =
	packet_generator.NextPacket(i, kPayloadLength);
	RtpPacketToSend rtp_packet(nullptr);
	rtp_packet.Parse(packet->data);
	sender.AddPacketAndGenerateFec(rtp_packet);
	}
	}
	std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
	sender.GetFecPackets();
	ASSERT_EQ(1U, fec_packets.size());
	EXPECT_TRUE(sender.GetFecPackets().empty());

	RtpPacketToSend* fec_packet = fec_packets.front().get();
	EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
	EXPECT_FALSE(fec_packet->Marker());
	EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
	EXPECT_EQ(kDeterministicSequenceNumber, fec_packet->SequenceNumber());
	EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
	EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
	}

	TEST(FlexfecSenderTest, ProtectTwoFramesWithTwoFecPackets) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	// FEC parameters selected to generate a single FEC packet per frame.
	FecProtectionParams params;
	params.fec_rate = 30;
	params.max_fec_frames = 1;
	params.fec_mask_type = kFecMaskRandom;
	constexpr size_t kNumFrames = 2;
	constexpr size_t kNumPacketsPerFrame = 2;
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);
	sender.SetProtectionParameters(params, params);

	AugmentedPacketGenerator packet_generator(kMediaSsrc);
	for (size_t i = 0; i < kNumFrames; ++i) {
	packet_generator.NewFrame(kNumPacketsPerFrame);
	for (size_t j = 0; j < kNumPacketsPerFrame; ++j) {
	std::unique_ptr<AugmentedPacket> packet =
	packet_generator.NextPacket(i, kPayloadLength);
	RtpPacketToSend rtp_packet(nullptr);
	rtp_packet.Parse(packet->data);
	sender.AddPacketAndGenerateFec(rtp_packet);
	}
	std::vector<std::unique_ptr<RtpPacketToSend>> fec_packets =
	sender.GetFecPackets();
	ASSERT_EQ(1U, fec_packets.size());
	EXPECT_TRUE(sender.GetFecPackets().empty());

	RtpPacketToSend* fec_packet = fec_packets.front().get();
	EXPECT_EQ(kRtpHeaderSize, fec_packet->headers_size());
	EXPECT_FALSE(fec_packet->Marker());
	EXPECT_EQ(kFlexfecPayloadType, fec_packet->PayloadType());
	EXPECT_EQ(static_cast<uint16_t>(kDeterministicSequenceNumber + i),
	fec_packet->SequenceNumber());
	EXPECT_EQ(kDeterministicTimestamp, fec_packet->Timestamp());
	EXPECT_EQ(kFlexfecSsrc, fec_packet->Ssrc());
	}
	}

	// In the tests, we only consider RTP header extensions that are useful for BWE.
	TEST(FlexfecSenderTest, NoRtpHeaderExtensionsForBweByDefault) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{};
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
	nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
	EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
	EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
	}

	TEST(FlexfecSenderTest, RegisterAbsoluteSendTimeRtpHeaderExtension) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kAbsSendTimeUri, 1}};
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
	nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_TRUE(fec_packet->HasExtension<AbsoluteSendTime>());
	EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
	EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
	}

	TEST(FlexfecSenderTest, RegisterTransmissionOffsetRtpHeaderExtension) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kTimestampOffsetUri, 1}};
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
	nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
	EXPECT_TRUE(fec_packet->HasExtension<TransmissionOffset>());
	EXPECT_FALSE(fec_packet->HasExtension<TransportSequenceNumber>());
	}

	TEST(FlexfecSenderTest, RegisterTransportSequenceNumberRtpHeaderExtension) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kTransportSequenceNumberUri, 1}};
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
	nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_FALSE(fec_packet->HasExtension<AbsoluteSendTime>());
	EXPECT_FALSE(fec_packet->HasExtension<TransmissionOffset>());
	EXPECT_TRUE(fec_packet->HasExtension<TransportSequenceNumber>());
	}

	TEST(FlexfecSenderTest, RegisterAllRtpHeaderExtensionsForBwe) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kAbsSendTimeUri, 1},
	{RtpExtension::kTimestampOffsetUri, 2},
	{RtpExtension::kTransportSequenceNumberUri, 3}};
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions, kNoRtpHeaderExtensionSizes,
	nullptr /* rtp_state */);
	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	EXPECT_TRUE(fec_packet->HasExtension<AbsoluteSendTime>());
	EXPECT_TRUE(fec_packet->HasExtension<TransmissionOffset>());
	EXPECT_TRUE(fec_packet->HasExtension<TransportSequenceNumber>());
	}

	TEST(FlexfecSenderTest, MaxPacketOverhead) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, nullptr /* rtp_state */);

	EXPECT_EQ(kFlexfecMaxHeaderSize, sender.MaxPacketOverhead());
	}

	TEST(FlexfecSenderTest, MaxPacketOverheadWithExtensions) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kAbsSendTimeUri, 1},
	{RtpExtension::kTimestampOffsetUri, 2},
	{RtpExtension::kTransportSequenceNumberUri, 3}};
	const size_t kExtensionHeaderLength = 1;
	const size_t kRtpOneByteHeaderLength = 4;
	const size_t kExtensionsTotalSize =
	Word32Align(kRtpOneByteHeaderLength + kExtensionHeaderLength +
	AbsoluteSendTime::kValueSizeBytes + kExtensionHeaderLength +
	TransmissionOffset::kValueSizeBytes + kExtensionHeaderLength +
	TransportSequenceNumber::kValueSizeBytes);
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kRtpHeaderExtensions,
	RTPSender::FecExtensionSizes(), nullptr /* rtp_state */);

	EXPECT_EQ(kExtensionsTotalSize + kFlexfecMaxHeaderSize,
	sender.MaxPacketOverhead());
	}

	TEST(FlexfecSenderTest, MidIncludedInPacketsWhenSet) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	const std::vector<RtpExtension> kRtpHeaderExtensions{
	{RtpExtension::kMidUri, 1}};
	const char kMid[] = "mid";
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc, kMid,
	kRtpHeaderExtensions, RTPSender::FecExtensionSizes(),
	nullptr /* rtp_state */);

	auto fec_packet = GenerateSingleFlexfecPacket(&sender);

	std::string mid;
	ASSERT_TRUE(fec_packet->GetExtension<RtpMid>(&mid));
	EXPECT_EQ(kMid, mid);
	}

	TEST(FlexfecSenderTest, SetsAndGetsRtpState) {
	SimulatedClock clock(kInitialSimulatedClockTime);
	const Environment env = CreateEnvironment(&clock);
	RtpState initial_rtp_state;
	initial_rtp_state.sequence_number = 100;
	initial_rtp_state.start_timestamp = 200;
	FlexfecSender sender(env, kFlexfecPayloadType, kFlexfecSsrc, kMediaSsrc,
	kNoMid, kNoRtpHeaderExtensions,
	kNoRtpHeaderExtensionSizes, &initial_rtp_state);

	auto fec_packet = GenerateSingleFlexfecPacket(&sender);
	EXPECT_EQ(initial_rtp_state.sequence_number, fec_packet->SequenceNumber());
	EXPECT_EQ(initial_rtp_state.start_timestamp, fec_packet->Timestamp());

	clock.AdvanceTimeMilliseconds(1000);
	fec_packet = GenerateSingleFlexfecPacket(&sender);
	EXPECT_EQ(initial_rtp_state.sequence_number + 1,
	fec_packet->SequenceNumber());
	EXPECT_EQ(initial_rtp_state.start_timestamp + 1 * kVideoPayloadTypeFrequency,
	fec_packet->Timestamp());

	RtpState updated_rtp_state = sender.GetRtpState().value();
	EXPECT_EQ(initial_rtp_state.sequence_number + 2,
	updated_rtp_state.sequence_number);
	EXPECT_EQ(initial_rtp_state.start_timestamp,
	updated_rtp_state.start_timestamp);
	}

	} // namespace webrtc