modules/video_coding/receiver_unittest.cc - src/webrtc - 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 <string.h>

 #include <list>
 #include <memory>
 #include <queue>
 #include <vector>

 #include "webrtc/modules/video_coding/encoded_frame.h"
 #include "webrtc/modules/video_coding/packet.h"
 #include "webrtc/modules/video_coding/receiver.h"
 #include "webrtc/modules/video_coding/test/stream_generator.h"
 #include "webrtc/modules/video_coding/test/test_util.h"
 #include "webrtc/modules/video_coding/timing.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/test/gtest.h"

 namespace webrtc {

 class TestVCMReceiver : public ::testing::Test {
  protected:
   TestVCMReceiver()
       : clock_(new SimulatedClock(0)),
         timing_(clock_.get()),
         receiver_(&timing_, clock_.get(), &event_factory_) {
     stream_generator_.reset(
         new StreamGenerator(0, clock_->TimeInMilliseconds()));
   }

   virtual void SetUp() { receiver_.Reset(); }

   int32_t InsertPacket(int index) {
     VCMPacket packet;
     bool packet_available = stream_generator_->GetPacket(&packet, index);
     EXPECT_TRUE(packet_available);
     if (!packet_available)
       return kGeneralError;  // Return here to avoid crashes below.
     return receiver_.InsertPacket(packet);
   }

   int32_t InsertPacketAndPop(int index) {
     VCMPacket packet;
     bool packet_available = stream_generator_->PopPacket(&packet, index);
     EXPECT_TRUE(packet_available);
     if (!packet_available)
       return kGeneralError;  // Return here to avoid crashes below.
     return receiver_.InsertPacket(packet);
   }

   int32_t InsertFrame(FrameType frame_type, bool complete) {
     int num_of_packets = complete ? 1 : 2;
     stream_generator_->GenerateFrame(
         frame_type, (frame_type != kEmptyFrame) ? num_of_packets : 0,
         (frame_type == kEmptyFrame) ? 1 : 0, clock_->TimeInMilliseconds());
     int32_t ret = InsertPacketAndPop(0);
     if (!complete) {
       // Drop the second packet.
       VCMPacket packet;
       stream_generator_->PopPacket(&packet, 0);
     }
     clock_->AdvanceTimeMilliseconds(kDefaultFramePeriodMs);
     return ret;
   }

   bool DecodeNextFrame() {
     VCMEncodedFrame* frame = receiver_.FrameForDecoding(0, false);
     if (!frame)
       return false;
     receiver_.ReleaseFrame(frame);
     return true;
   }

   std::unique_ptr<SimulatedClock> clock_;
   VCMTiming timing_;
   NullEventFactory event_factory_;
   VCMReceiver receiver_;
   std::unique_ptr<StreamGenerator> stream_generator_;
 };

 TEST_F(TestVCMReceiver, NonDecodableDuration_Empty) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   const int kMinDelayMs = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs);
   EXPECT_TRUE(DecodeNextFrame());
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_FALSE(request_key_frame);
 }

 TEST_F(TestVCMReceiver, NonDecodableDuration_NoKeyFrame) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   const int kNumFrames = kDefaultFrameRate * kMaxNonDecodableDuration / 1000;
   for (int i = 0; i < kNumFrames; ++i) {
     EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
   }
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_TRUE(request_key_frame);
 }

 TEST_F(TestVCMReceiver, NonDecodableDuration_OneIncomplete) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   const int kMaxNonDecodableDurationFrames =
       (kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
   const int kMinDelayMs = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   receiver_.SetMinReceiverDelay(kMinDelayMs);
   int64_t key_frame_inserted = clock_->TimeInMilliseconds();
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Insert an incomplete frame.
   EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
   // Insert enough frames to have too long non-decodable sequence.
   for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
     EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
   }
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
                                   key_frame_inserted);
   EXPECT_TRUE(DecodeNextFrame());
   // Make sure we get a key frame request.
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_TRUE(request_key_frame);
 }

 TEST_F(TestVCMReceiver, NonDecodableDuration_NoTrigger) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   const int kMaxNonDecodableDurationFrames =
       (kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
   const int kMinDelayMs = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   receiver_.SetMinReceiverDelay(kMinDelayMs);
   int64_t key_frame_inserted = clock_->TimeInMilliseconds();
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Insert an incomplete frame.
   EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
   // Insert all but one frame to not trigger a key frame request due to
   // too long duration of non-decodable frames.
   for (int i = 0; i < kMaxNonDecodableDurationFrames - 1; ++i) {
     EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
   }
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
                                   key_frame_inserted);
   EXPECT_TRUE(DecodeNextFrame());
   // Make sure we don't get a key frame request since we haven't generated
   // enough frames.
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_FALSE(request_key_frame);
 }

 TEST_F(TestVCMReceiver, NonDecodableDuration_NoTrigger2) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   const int kMaxNonDecodableDurationFrames =
       (kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
   const int kMinDelayMs = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   receiver_.SetMinReceiverDelay(kMinDelayMs);
   int64_t key_frame_inserted = clock_->TimeInMilliseconds();
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Insert enough frames to have too long non-decodable sequence, except that
   // we don't have any losses.
   for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
     EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
   }
   // Insert an incomplete frame.
   EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
                                   key_frame_inserted);
   EXPECT_TRUE(DecodeNextFrame());
   // Make sure we don't get a key frame request since the non-decodable duration
   // is only one frame.
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_FALSE(request_key_frame);
 }

 TEST_F(TestVCMReceiver, NonDecodableDuration_KeyFrameAfterIncompleteFrames) {
   // Enable NACK and with no RTT thresholds for disabling retransmission delay.
   receiver_.SetNackMode(kNack, -1, -1);
   const size_t kMaxNackListSize = 1000;
   const int kMaxPacketAgeToNack = 1000;
   const int kMaxNonDecodableDuration = 500;
   const int kMaxNonDecodableDurationFrames =
       (kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
   const int kMinDelayMs = 500;
   receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
                             kMaxNonDecodableDuration);
   receiver_.SetMinReceiverDelay(kMinDelayMs);
   int64_t key_frame_inserted = clock_->TimeInMilliseconds();
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Insert an incomplete frame.
   EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
   // Insert enough frames to have too long non-decodable sequence.
   for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
     EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
   }
   EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
   // Advance time until it's time to decode the key frame.
   clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
                                   key_frame_inserted);
   EXPECT_TRUE(DecodeNextFrame());
   // Make sure we don't get a key frame request since we have a key frame
   // in the list.
   bool request_key_frame = false;
   std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
   EXPECT_FALSE(request_key_frame);
 }

 // A simulated clock, when time elapses, will insert frames into the jitter
 // buffer, based on initial settings.
 class SimulatedClockWithFrames : public SimulatedClock {
  public:
   SimulatedClockWithFrames(StreamGenerator* stream_generator,
                            VCMReceiver* receiver)
       : SimulatedClock(0),
         stream_generator_(stream_generator),
         receiver_(receiver) {}
   virtual ~SimulatedClockWithFrames() {}

   // If |stop_on_frame| is true and next frame arrives between now and
   // now+|milliseconds|, the clock will be advanced to the arrival time of next
   // frame.
   // Otherwise, the clock will be advanced by |milliseconds|.
   //
   // For both cases, a frame will be inserted into the jitter buffer at the
   // instant when the clock time is timestamps_.front().arrive_time.
   //
   // Return true if some frame arrives between now and now+|milliseconds|.
   bool AdvanceTimeMilliseconds(int64_t milliseconds, bool stop_on_frame) {
     return AdvanceTimeMicroseconds(milliseconds * 1000, stop_on_frame);
   }

   bool AdvanceTimeMicroseconds(int64_t microseconds, bool stop_on_frame) {
     int64_t start_time = TimeInMicroseconds();
     int64_t end_time = start_time + microseconds;
     bool frame_injected = false;
     while (!timestamps_.empty() &&
            timestamps_.front().arrive_time <= end_time) {
       RTC_DCHECK(timestamps_.front().arrive_time >= start_time);

       SimulatedClock::AdvanceTimeMicroseconds(timestamps_.front().arrive_time -
                                               TimeInMicroseconds());
       GenerateAndInsertFrame((timestamps_.front().render_time + 500) / 1000);
       timestamps_.pop();
       frame_injected = true;

       if (stop_on_frame)
         return frame_injected;
     }

     if (TimeInMicroseconds() < end_time) {
       SimulatedClock::AdvanceTimeMicroseconds(end_time - TimeInMicroseconds());
     }
     return frame_injected;
   }

   // Input timestamps are in unit Milliseconds.
   // And |arrive_timestamps| must be positive and in increasing order.
   // |arrive_timestamps| determine when we are going to insert frames into the
   // jitter buffer.
   // |render_timestamps| are the timestamps on the frame.
   void SetFrames(const int64_t* arrive_timestamps,
                  const int64_t* render_timestamps,
                  size_t size) {
     int64_t previous_arrive_timestamp = 0;
     for (size_t i = 0; i < size; i++) {
       RTC_CHECK(arrive_timestamps[i] >= previous_arrive_timestamp);
       timestamps_.push(TimestampPair(arrive_timestamps[i] * 1000,
                                      render_timestamps[i] * 1000));
       previous_arrive_timestamp = arrive_timestamps[i];
     }
   }

  private:
   struct TimestampPair {
     TimestampPair(int64_t arrive_timestamp, int64_t render_timestamp)
         : arrive_time(arrive_timestamp), render_time(render_timestamp) {}

     int64_t arrive_time;
     int64_t render_time;
   };

   void GenerateAndInsertFrame(int64_t render_timestamp_ms) {
     VCMPacket packet;
     stream_generator_->GenerateFrame(FrameType::kVideoFrameKey,
                                      1,  // media packets
                                      0,  // empty packets
                                      render_timestamp_ms);

     bool packet_available = stream_generator_->PopPacket(&packet, 0);
     EXPECT_TRUE(packet_available);
     if (!packet_available)
       return;  // Return here to avoid crashes below.
     receiver_->InsertPacket(packet);
   }

   std::queue<TimestampPair> timestamps_;
   StreamGenerator* stream_generator_;
   VCMReceiver* receiver_;
 };

 // Use a SimulatedClockWithFrames
 // Wait call will do either of these:
 // 1. If |stop_on_frame| is true, the clock will be turned to the exact instant
 // that the first frame comes and the frame will be inserted into the jitter
 // buffer, or the clock will be turned to now + |max_time| if no frame comes in
 // the window.
 // 2. If |stop_on_frame| is false, the clock will be turn to now + |max_time|,
 // and all the frames arriving between now and now + |max_time| will be
 // inserted into the jitter buffer.
 //
 // This is used to simulate the JitterBuffer getting packets from internet as
 // time elapses.

 class FrameInjectEvent : public EventWrapper {
  public:
   FrameInjectEvent(SimulatedClockWithFrames* clock, bool stop_on_frame)
       : clock_(clock), stop_on_frame_(stop_on_frame) {}

   bool Set() override { return true; }

   EventTypeWrapper Wait(unsigned long max_time) override {  // NOLINT
     if (clock_->AdvanceTimeMilliseconds(max_time, stop_on_frame_) &&
         stop_on_frame_) {
       return EventTypeWrapper::kEventSignaled;
     } else {
       return EventTypeWrapper::kEventTimeout;
     }
   }

  private:
   SimulatedClockWithFrames* clock_;
   bool stop_on_frame_;
 };

 class VCMReceiverTimingTest : public ::testing::Test {
  protected:
   VCMReceiverTimingTest()

       : clock_(&stream_generator_, &receiver_),
         stream_generator_(0, clock_.TimeInMilliseconds()),
         timing_(&clock_),
         receiver_(
             &timing_,
             &clock_,
             std::unique_ptr<EventWrapper>(new FrameInjectEvent(&clock_, false)),
             std::unique_ptr<EventWrapper>(
                 new FrameInjectEvent(&clock_, true))) {}

   virtual void SetUp() { receiver_.Reset(); }

   SimulatedClockWithFrames clock_;
   StreamGenerator stream_generator_;
   VCMTiming timing_;
   VCMReceiver receiver_;
 };

 // Test whether VCMReceiver::FrameForDecoding handles parameter
 // |max_wait_time_ms| correctly:
 // 1. The function execution should never take more than |max_wait_time_ms|.
 // 2. If the function exit before now + |max_wait_time_ms|, a frame must be
 //    returned.
 TEST_F(VCMReceiverTimingTest, FrameForDecoding) {
   const size_t kNumFrames = 100;
   const int kFramePeriod = 40;
   int64_t arrive_timestamps[kNumFrames];
   int64_t render_timestamps[kNumFrames];

   // Construct test samples.
   // render_timestamps are the timestamps stored in the Frame;
   // arrive_timestamps controls when the Frame packet got received.
   for (size_t i = 0; i < kNumFrames; i++) {
     // Preset frame rate to 25Hz.
     // But we add a reasonable deviation to arrive_timestamps to mimic Internet
     // fluctuation.
     arrive_timestamps[i] =
         (i + 1) * kFramePeriod + (i % 10) * ((i % 2) ? 1 : -1);
     render_timestamps[i] = (i + 1) * kFramePeriod;
   }

   clock_.SetFrames(arrive_timestamps, render_timestamps, kNumFrames);

   // Record how many frames we finally get out of the receiver.
   size_t num_frames_return = 0;

   const int64_t kMaxWaitTime = 30;

   // Ideally, we should get all frames that we input in InitializeFrames.
   // In the case that FrameForDecoding kills frames by error, we rely on the
   // build bot to kill the test.
   while (num_frames_return < kNumFrames) {
     int64_t start_time = clock_.TimeInMilliseconds();
     VCMEncodedFrame* frame = receiver_.FrameForDecoding(kMaxWaitTime, false);
     int64_t end_time = clock_.TimeInMilliseconds();

     // In any case the FrameForDecoding should not wait longer than
     // max_wait_time.
     // In the case that we did not get a frame, it should have been waiting for
     // exactly max_wait_time. (By the testing samples we constructed above, we
     // are sure there is no timing error, so the only case it returns with NULL
     // is that it runs out of time.)
     if (frame) {
       receiver_.ReleaseFrame(frame);
       ++num_frames_return;
       EXPECT_GE(kMaxWaitTime, end_time - start_time);
     } else {
       EXPECT_EQ(kMaxWaitTime, end_time - start_time);
     }
   }
 }

 // Test whether VCMReceiver::FrameForDecoding handles parameter
 // |prefer_late_decoding| and |max_wait_time_ms| correctly:
 // 1. The function execution should never take more than |max_wait_time_ms|.
 // 2. If the function exit before now + |max_wait_time_ms|, a frame must be
 //    returned and the end time must be equal to the render timestamp - delay
 //    for decoding and rendering.
 TEST_F(VCMReceiverTimingTest, FrameForDecodingPreferLateDecoding) {
   const size_t kNumFrames = 100;
   const int kFramePeriod = 40;

   int64_t arrive_timestamps[kNumFrames];
   int64_t render_timestamps[kNumFrames];

   int render_delay_ms;
   int max_decode_ms;
   int dummy;
   timing_.GetTimings(&dummy, &max_decode_ms, &dummy, &dummy, &dummy, &dummy,
                      &render_delay_ms);

   // Construct test samples.
   // render_timestamps are the timestamps stored in the Frame;
   // arrive_timestamps controls when the Frame packet got received.
   for (size_t i = 0; i < kNumFrames; i++) {
     // Preset frame rate to 25Hz.
     // But we add a reasonable deviation to arrive_timestamps to mimic Internet
     // fluctuation.
     arrive_timestamps[i] =
         (i + 1) * kFramePeriod + (i % 10) * ((i % 2) ? 1 : -1);
     render_timestamps[i] = (i + 1) * kFramePeriod;
   }

   clock_.SetFrames(arrive_timestamps, render_timestamps, kNumFrames);

   // Record how many frames we finally get out of the receiver.
   size_t num_frames_return = 0;
   const int64_t kMaxWaitTime = 30;
   bool prefer_late_decoding = true;
   while (num_frames_return < kNumFrames) {
     int64_t start_time = clock_.TimeInMilliseconds();

     VCMEncodedFrame* frame =
         receiver_.FrameForDecoding(kMaxWaitTime, prefer_late_decoding);
     int64_t end_time = clock_.TimeInMilliseconds();
     if (frame) {
       EXPECT_EQ(frame->RenderTimeMs() - max_decode_ms - render_delay_ms,
                 end_time);
       receiver_.ReleaseFrame(frame);
       ++num_frames_return;
     } else {
       EXPECT_EQ(kMaxWaitTime, end_time - start_time);
     }
   }
 }

 }  // 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 <string.h>

	#include <list>
	#include <memory>
	#include <queue>
	#include <vector>

	#include "webrtc/modules/video_coding/encoded_frame.h"
	#include "webrtc/modules/video_coding/packet.h"
	#include "webrtc/modules/video_coding/receiver.h"
	#include "webrtc/modules/video_coding/test/stream_generator.h"
	#include "webrtc/modules/video_coding/test/test_util.h"
	#include "webrtc/modules/video_coding/timing.h"
	#include "webrtc/rtc_base/checks.h"
	#include "webrtc/system_wrappers/include/clock.h"
	#include "webrtc/test/gtest.h"

	namespace webrtc {

	class TestVCMReceiver : public ::testing::Test {
	protected:
	TestVCMReceiver()
	: clock_(new SimulatedClock(0)),
	timing_(clock_.get()),
	receiver_(&timing_, clock_.get(), &event_factory_) {
	stream_generator_.reset(
	new StreamGenerator(0, clock_->TimeInMilliseconds()));
	}

	virtual void SetUp() { receiver_.Reset(); }

	int32_t InsertPacket(int index) {
	VCMPacket packet;
	bool packet_available = stream_generator_->GetPacket(&packet, index);
	EXPECT_TRUE(packet_available);
	if (!packet_available)
	return kGeneralError; // Return here to avoid crashes below.
	return receiver_.InsertPacket(packet);
	}

	int32_t InsertPacketAndPop(int index) {
	VCMPacket packet;
	bool packet_available = stream_generator_->PopPacket(&packet, index);
	EXPECT_TRUE(packet_available);
	if (!packet_available)
	return kGeneralError; // Return here to avoid crashes below.
	return receiver_.InsertPacket(packet);
	}

	int32_t InsertFrame(FrameType frame_type, bool complete) {
	int num_of_packets = complete ? 1 : 2;
	stream_generator_->GenerateFrame(
	frame_type, (frame_type != kEmptyFrame) ? num_of_packets : 0,
	(frame_type == kEmptyFrame) ? 1 : 0, clock_->TimeInMilliseconds());
	int32_t ret = InsertPacketAndPop(0);
	if (!complete) {
	// Drop the second packet.
	VCMPacket packet;
	stream_generator_->PopPacket(&packet, 0);
	}
	clock_->AdvanceTimeMilliseconds(kDefaultFramePeriodMs);
	return ret;
	}

	bool DecodeNextFrame() {
	VCMEncodedFrame* frame = receiver_.FrameForDecoding(0, false);
	if (!frame)
	return false;
	receiver_.ReleaseFrame(frame);
	return true;
	}

	std::unique_ptr<SimulatedClock> clock_;
	VCMTiming timing_;
	NullEventFactory event_factory_;
	VCMReceiver receiver_;
	std::unique_ptr<StreamGenerator> stream_generator_;
	};

	TEST_F(TestVCMReceiver, NonDecodableDuration_Empty) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	const int kMinDelayMs = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Advance time until it's time to decode the key frame.
	clock_->AdvanceTimeMilliseconds(kMinDelayMs);
	EXPECT_TRUE(DecodeNextFrame());
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_FALSE(request_key_frame);
	}

	TEST_F(TestVCMReceiver, NonDecodableDuration_NoKeyFrame) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	const int kNumFrames = kDefaultFrameRate * kMaxNonDecodableDuration / 1000;
	for (int i = 0; i < kNumFrames; ++i) {
	EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
	}
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_TRUE(request_key_frame);
	}

	TEST_F(TestVCMReceiver, NonDecodableDuration_OneIncomplete) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	const int kMaxNonDecodableDurationFrames =
	(kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
	const int kMinDelayMs = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	receiver_.SetMinReceiverDelay(kMinDelayMs);
	int64_t key_frame_inserted = clock_->TimeInMilliseconds();
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Insert an incomplete frame.
	EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
	// Insert enough frames to have too long non-decodable sequence.
	for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
	EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
	}
	// Advance time until it's time to decode the key frame.
	clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
	key_frame_inserted);
	EXPECT_TRUE(DecodeNextFrame());
	// Make sure we get a key frame request.
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_TRUE(request_key_frame);
	}

	TEST_F(TestVCMReceiver, NonDecodableDuration_NoTrigger) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	const int kMaxNonDecodableDurationFrames =
	(kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
	const int kMinDelayMs = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	receiver_.SetMinReceiverDelay(kMinDelayMs);
	int64_t key_frame_inserted = clock_->TimeInMilliseconds();
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Insert an incomplete frame.
	EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
	// Insert all but one frame to not trigger a key frame request due to
	// too long duration of non-decodable frames.
	for (int i = 0; i < kMaxNonDecodableDurationFrames - 1; ++i) {
	EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
	}
	// Advance time until it's time to decode the key frame.
	clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
	key_frame_inserted);
	EXPECT_TRUE(DecodeNextFrame());
	// Make sure we don't get a key frame request since we haven't generated
	// enough frames.
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_FALSE(request_key_frame);
	}

	TEST_F(TestVCMReceiver, NonDecodableDuration_NoTrigger2) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	const int kMaxNonDecodableDurationFrames =
	(kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
	const int kMinDelayMs = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	receiver_.SetMinReceiverDelay(kMinDelayMs);
	int64_t key_frame_inserted = clock_->TimeInMilliseconds();
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Insert enough frames to have too long non-decodable sequence, except that
	// we don't have any losses.
	for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
	EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
	}
	// Insert an incomplete frame.
	EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
	// Advance time until it's time to decode the key frame.
	clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
	key_frame_inserted);
	EXPECT_TRUE(DecodeNextFrame());
	// Make sure we don't get a key frame request since the non-decodable duration
	// is only one frame.
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_FALSE(request_key_frame);
	}

	TEST_F(TestVCMReceiver, NonDecodableDuration_KeyFrameAfterIncompleteFrames) {
	// Enable NACK and with no RTT thresholds for disabling retransmission delay.
	receiver_.SetNackMode(kNack, -1, -1);
	const size_t kMaxNackListSize = 1000;
	const int kMaxPacketAgeToNack = 1000;
	const int kMaxNonDecodableDuration = 500;
	const int kMaxNonDecodableDurationFrames =
	(kDefaultFrameRate * kMaxNonDecodableDuration + 500) / 1000;
	const int kMinDelayMs = 500;
	receiver_.SetNackSettings(kMaxNackListSize, kMaxPacketAgeToNack,
	kMaxNonDecodableDuration);
	receiver_.SetMinReceiverDelay(kMinDelayMs);
	int64_t key_frame_inserted = clock_->TimeInMilliseconds();
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Insert an incomplete frame.
	EXPECT_GE(InsertFrame(kVideoFrameDelta, false), kNoError);
	// Insert enough frames to have too long non-decodable sequence.
	for (int i = 0; i < kMaxNonDecodableDurationFrames; ++i) {
	EXPECT_GE(InsertFrame(kVideoFrameDelta, true), kNoError);
	}
	EXPECT_GE(InsertFrame(kVideoFrameKey, true), kNoError);
	// Advance time until it's time to decode the key frame.
	clock_->AdvanceTimeMilliseconds(kMinDelayMs - clock_->TimeInMilliseconds() -
	key_frame_inserted);
	EXPECT_TRUE(DecodeNextFrame());
	// Make sure we don't get a key frame request since we have a key frame
	// in the list.
	bool request_key_frame = false;
	std::vector<uint16_t> nack_list = receiver_.NackList(&request_key_frame);
	EXPECT_FALSE(request_key_frame);
	}

	// A simulated clock, when time elapses, will insert frames into the jitter
	// buffer, based on initial settings.
	class SimulatedClockWithFrames : public SimulatedClock {
	public:
	SimulatedClockWithFrames(StreamGenerator* stream_generator,
	VCMReceiver* receiver)
	: SimulatedClock(0),
	stream_generator_(stream_generator),
	receiver_(receiver) {}
	virtual ~SimulatedClockWithFrames() {}

	// If \|stop_on_frame\| is true and next frame arrives between now and
	// now+\|milliseconds\|, the clock will be advanced to the arrival time of next
	// frame.
	// Otherwise, the clock will be advanced by \|milliseconds\|.
	//
	// For both cases, a frame will be inserted into the jitter buffer at the
	// instant when the clock time is timestamps_.front().arrive_time.
	//
	// Return true if some frame arrives between now and now+\|milliseconds\|.
	bool AdvanceTimeMilliseconds(int64_t milliseconds, bool stop_on_frame) {
	return AdvanceTimeMicroseconds(milliseconds * 1000, stop_on_frame);
	}

	bool AdvanceTimeMicroseconds(int64_t microseconds, bool stop_on_frame) {
	int64_t start_time = TimeInMicroseconds();
	int64_t end_time = start_time + microseconds;
	bool frame_injected = false;
	while (!timestamps_.empty() &&
	timestamps_.front().arrive_time <= end_time) {
	RTC_DCHECK(timestamps_.front().arrive_time >= start_time);

	SimulatedClock::AdvanceTimeMicroseconds(timestamps_.front().arrive_time -
	TimeInMicroseconds());
	GenerateAndInsertFrame((timestamps_.front().render_time + 500) / 1000);
	timestamps_.pop();
	frame_injected = true;

	if (stop_on_frame)
	return frame_injected;
	}

	if (TimeInMicroseconds() < end_time) {
	SimulatedClock::AdvanceTimeMicroseconds(end_time - TimeInMicroseconds());
	}
	return frame_injected;
	}

	// Input timestamps are in unit Milliseconds.
	// And \|arrive_timestamps\| must be positive and in increasing order.
	// \|arrive_timestamps\| determine when we are going to insert frames into the
	// jitter buffer.
	// \|render_timestamps\| are the timestamps on the frame.
	void SetFrames(const int64_t* arrive_timestamps,
	const int64_t* render_timestamps,
	size_t size) {
	int64_t previous_arrive_timestamp = 0;
	for (size_t i = 0; i < size; i++) {
	RTC_CHECK(arrive_timestamps[i] >= previous_arrive_timestamp);
	timestamps_.push(TimestampPair(arrive_timestamps[i] * 1000,
	render_timestamps[i] * 1000));
	previous_arrive_timestamp = arrive_timestamps[i];
	}
	}

	private:
	struct TimestampPair {
	TimestampPair(int64_t arrive_timestamp, int64_t render_timestamp)
	: arrive_time(arrive_timestamp), render_time(render_timestamp) {}

	int64_t arrive_time;
	int64_t render_time;
	};

	void GenerateAndInsertFrame(int64_t render_timestamp_ms) {
	VCMPacket packet;
	stream_generator_->GenerateFrame(FrameType::kVideoFrameKey,
	1, // media packets
	0, // empty packets
	render_timestamp_ms);

	bool packet_available = stream_generator_->PopPacket(&packet, 0);
	EXPECT_TRUE(packet_available);
	if (!packet_available)
	return; // Return here to avoid crashes below.
	receiver_->InsertPacket(packet);
	}

	std::queue<TimestampPair> timestamps_;
	StreamGenerator* stream_generator_;
	VCMReceiver* receiver_;
	};

	// Use a SimulatedClockWithFrames
	// Wait call will do either of these:
	// 1. If \|stop_on_frame\| is true, the clock will be turned to the exact instant
	// that the first frame comes and the frame will be inserted into the jitter
	// buffer, or the clock will be turned to now + \|max_time\| if no frame comes in
	// the window.
	// 2. If \|stop_on_frame\| is false, the clock will be turn to now + \|max_time\|,
	// and all the frames arriving between now and now + \|max_time\| will be
	// inserted into the jitter buffer.
	//
	// This is used to simulate the JitterBuffer getting packets from internet as
	// time elapses.

	class FrameInjectEvent : public EventWrapper {
	public:
	FrameInjectEvent(SimulatedClockWithFrames* clock, bool stop_on_frame)
	: clock_(clock), stop_on_frame_(stop_on_frame) {}

	bool Set() override { return true; }

	EventTypeWrapper Wait(unsigned long max_time) override { // NOLINT
	if (clock_->AdvanceTimeMilliseconds(max_time, stop_on_frame_) &&
	stop_on_frame_) {
	return EventTypeWrapper::kEventSignaled;
	} else {
	return EventTypeWrapper::kEventTimeout;
	}
	}

	private:
	SimulatedClockWithFrames* clock_;
	bool stop_on_frame_;
	};

	class VCMReceiverTimingTest : public ::testing::Test {
	protected:
	VCMReceiverTimingTest()

	: clock_(&stream_generator_, &receiver_),
	stream_generator_(0, clock_.TimeInMilliseconds()),
	timing_(&clock_),
	receiver_(
	&timing_,
	&clock_,
	std::unique_ptr<EventWrapper>(new FrameInjectEvent(&clock_, false)),
	std::unique_ptr<EventWrapper>(
	new FrameInjectEvent(&clock_, true))) {}

	virtual void SetUp() { receiver_.Reset(); }

	SimulatedClockWithFrames clock_;
	StreamGenerator stream_generator_;
	VCMTiming timing_;
	VCMReceiver receiver_;
	};

	// Test whether VCMReceiver::FrameForDecoding handles parameter
	// \|max_wait_time_ms\| correctly:
	// 1. The function execution should never take more than \|max_wait_time_ms\|.
	// 2. If the function exit before now + \|max_wait_time_ms\|, a frame must be
	// returned.
	TEST_F(VCMReceiverTimingTest, FrameForDecoding) {
	const size_t kNumFrames = 100;
	const int kFramePeriod = 40;
	int64_t arrive_timestamps[kNumFrames];
	int64_t render_timestamps[kNumFrames];

	// Construct test samples.
	// render_timestamps are the timestamps stored in the Frame;
	// arrive_timestamps controls when the Frame packet got received.
	for (size_t i = 0; i < kNumFrames; i++) {
	// Preset frame rate to 25Hz.
	// But we add a reasonable deviation to arrive_timestamps to mimic Internet
	// fluctuation.
	arrive_timestamps[i] =
	(i + 1) * kFramePeriod + (i % 10) * ((i % 2) ? 1 : -1);
	render_timestamps[i] = (i + 1) * kFramePeriod;
	}

	clock_.SetFrames(arrive_timestamps, render_timestamps, kNumFrames);

	// Record how many frames we finally get out of the receiver.
	size_t num_frames_return = 0;

	const int64_t kMaxWaitTime = 30;

	// Ideally, we should get all frames that we input in InitializeFrames.
	// In the case that FrameForDecoding kills frames by error, we rely on the
	// build bot to kill the test.
	while (num_frames_return < kNumFrames) {
	int64_t start_time = clock_.TimeInMilliseconds();
	VCMEncodedFrame* frame = receiver_.FrameForDecoding(kMaxWaitTime, false);
	int64_t end_time = clock_.TimeInMilliseconds();

	// In any case the FrameForDecoding should not wait longer than
	// max_wait_time.
	// In the case that we did not get a frame, it should have been waiting for
	// exactly max_wait_time. (By the testing samples we constructed above, we
	// are sure there is no timing error, so the only case it returns with NULL
	// is that it runs out of time.)
	if (frame) {
	receiver_.ReleaseFrame(frame);
	++num_frames_return;
	EXPECT_GE(kMaxWaitTime, end_time - start_time);
	} else {
	EXPECT_EQ(kMaxWaitTime, end_time - start_time);
	}
	}
	}

	// Test whether VCMReceiver::FrameForDecoding handles parameter
	// \|prefer_late_decoding\| and \|max_wait_time_ms\| correctly:
	// 1. The function execution should never take more than \|max_wait_time_ms\|.
	// 2. If the function exit before now + \|max_wait_time_ms\|, a frame must be
	// returned and the end time must be equal to the render timestamp - delay
	// for decoding and rendering.
	TEST_F(VCMReceiverTimingTest, FrameForDecodingPreferLateDecoding) {
	const size_t kNumFrames = 100;
	const int kFramePeriod = 40;

	int64_t arrive_timestamps[kNumFrames];
	int64_t render_timestamps[kNumFrames];

	int render_delay_ms;
	int max_decode_ms;
	int dummy;
	timing_.GetTimings(&dummy, &max_decode_ms, &dummy, &dummy, &dummy, &dummy,
	&render_delay_ms);

	// Construct test samples.
	// render_timestamps are the timestamps stored in the Frame;
	// arrive_timestamps controls when the Frame packet got received.
	for (size_t i = 0; i < kNumFrames; i++) {
	// Preset frame rate to 25Hz.
	// But we add a reasonable deviation to arrive_timestamps to mimic Internet
	// fluctuation.
	arrive_timestamps[i] =
	(i + 1) * kFramePeriod + (i % 10) * ((i % 2) ? 1 : -1);
	render_timestamps[i] = (i + 1) * kFramePeriod;
	}

	clock_.SetFrames(arrive_timestamps, render_timestamps, kNumFrames);

	// Record how many frames we finally get out of the receiver.
	size_t num_frames_return = 0;
	const int64_t kMaxWaitTime = 30;
	bool prefer_late_decoding = true;
	while (num_frames_return < kNumFrames) {
	int64_t start_time = clock_.TimeInMilliseconds();

	VCMEncodedFrame* frame =
	receiver_.FrameForDecoding(kMaxWaitTime, prefer_late_decoding);
	int64_t end_time = clock_.TimeInMilliseconds();
	if (frame) {
	EXPECT_EQ(frame->RenderTimeMs() - max_decode_ms - render_delay_ms,
	end_time);
	receiver_.ReleaseFrame(frame);
	++num_frames_return;
	} else {
	EXPECT_EQ(kMaxWaitTime, end_time - start_time);
	}
	}
	}

	} // namespace webrtc