modules/audio_processing/aec/system_delay_unittest.cc - src/webrtc - Git at Google

 /*
  *  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 "testing/gtest/include/gtest/gtest.h"

 extern "C" {
 #include "webrtc/modules/audio_processing/aec/aec_core.h"
 }
 #include "webrtc/modules/audio_processing/aec/echo_cancellation_internal.h"
 #include "webrtc/modules/audio_processing/aec/include/echo_cancellation.h"
 #include "webrtc/typedefs.h"

 namespace {

 class SystemDelayTest : public ::testing::Test {
  protected:
   SystemDelayTest();
   virtual void SetUp();
   virtual void TearDown();

   // Initialization of AEC handle with respect to |sample_rate_hz|. Since the
   // device sample rate is unimportant we set that value to 48000 Hz.
   void Init(int sample_rate_hz);

   // Makes one render call and one capture call in that specific order.
   void RenderAndCapture(int device_buffer_ms);

   // Fills up the far-end buffer with respect to the default device buffer size.
   int BufferFillUp();

   // Runs and verifies the behavior in a stable startup procedure.
   void RunStableStartup();

   // Maps buffer size in ms into samples, taking the unprocessed frame into
   // account.
   int MapBufferSizeToSamples(int size_in_ms);

   void* handle_;
   aecpc_t* self_;
   int samples_per_frame_;
   // Dummy input/output speech data.
   int16_t far_[160];
   int16_t near_[160];
   int16_t out_[160];
 };

 SystemDelayTest::SystemDelayTest()
     : handle_(NULL), self_(NULL), samples_per_frame_(0) {
   // Dummy input data are set with more or less arbitrary non-zero values.
   memset(far_, 1, sizeof(far_));
   memset(near_, 2, sizeof(near_));
   memset(out_, 0, sizeof(out_));
 }

 void SystemDelayTest::SetUp() {
   ASSERT_EQ(0, WebRtcAec_Create(&handle_));
   self_ = reinterpret_cast<aecpc_t*>(handle_);
 }

 void SystemDelayTest::TearDown() {
   // Free AEC
   ASSERT_EQ(0, WebRtcAec_Free(handle_));
   handle_ = NULL;
 }

 // In SWB mode nothing is added to the buffer handling with respect to
 // functionality compared to WB. We therefore only verify behavior in NB and WB.
 static const int kSampleRateHz[] = {8000, 16000};
 static const size_t kNumSampleRates =
     sizeof(kSampleRateHz) / sizeof(*kSampleRateHz);

 // Default audio device buffer size used.
 static const int kDeviceBufMs = 100;

 // Requirement for a stable device convergence time in ms. Should converge in
 // less than |kStableConvergenceMs|.
 static const int kStableConvergenceMs = 100;

 // Maximum convergence time in ms. This means that we should leave the startup
 // phase after |kMaxConvergenceMs| independent of device buffer stability
 // conditions.
 static const int kMaxConvergenceMs = 500;

 void SystemDelayTest::Init(int sample_rate_hz) {
   // Initialize AEC
   EXPECT_EQ(0, WebRtcAec_Init(handle_, sample_rate_hz, 48000));

   // One frame equals 10 ms of data.
   samples_per_frame_ = sample_rate_hz / 100;
 }

 void SystemDelayTest::RenderAndCapture(int device_buffer_ms) {
   EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
   EXPECT_EQ(0,
             WebRtcAec_Process(handle_,
                               near_,
                               NULL,
                               out_,
                               NULL,
                               samples_per_frame_,
                               device_buffer_ms,
                               0));
 }

 int SystemDelayTest::BufferFillUp() {
   // To make sure we have a full buffer when we verify stability we first fill
   // up the far-end buffer with the same amount as we will report in through
   // Process().
   int buffer_size = 0;
   for (int i = 0; i < kDeviceBufMs / 10; i++) {
     EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
     buffer_size += samples_per_frame_;
     EXPECT_EQ(buffer_size, WebRtcAec_system_delay(self_->aec));
   }
   return buffer_size;
 }

 void SystemDelayTest::RunStableStartup() {
   // To make sure we have a full buffer when we verify stability we first fill
   // up the far-end buffer with the same amount as we will report in through
   // Process().
   int buffer_size = BufferFillUp();
   // A stable device should be accepted and put in a regular process mode within
   // |kStableConvergenceMs|.
   int process_time_ms = 0;
   for (; process_time_ms < kStableConvergenceMs; process_time_ms += 10) {
     RenderAndCapture(kDeviceBufMs);
     buffer_size += samples_per_frame_;
     if (self_->startup_phase == 0) {
       // We have left the startup phase.
       break;
     }
   }
   // Verify convergence time.
   EXPECT_GT(kStableConvergenceMs, process_time_ms);
   // Verify that the buffer has been flushed.
   EXPECT_GE(buffer_size, WebRtcAec_system_delay(self_->aec));
 }

 int SystemDelayTest::MapBufferSizeToSamples(int size_in_ms) {
   // The extra 10 ms corresponds to the unprocessed frame.
   return (size_in_ms + 10) * samples_per_frame_ / 10;
 }

 // The tests should meet basic requirements and not be adjusted to what is
 // actually implemented. If we don't get good code coverage this way we either
 // lack in tests or have unnecessary code.
 // General requirements:
 // 1) If we add far-end data the system delay should be increased with the same
 //    amount we add.
 // 2) If the far-end buffer is full we should flush the oldest data to make room
 //    for the new. In this case the system delay is unaffected.
 // 3) There should exist a startup phase in which the buffer size is to be
 //    determined. In this phase no cancellation should be performed.
 // 4) Under stable conditions (small variations in device buffer sizes) the AEC
 //    should determine an appropriate local buffer size within
 //    |kStableConvergenceMs| ms.
 // 5) Under unstable conditions the AEC should make a decision within
 //    |kMaxConvergenceMs| ms.
 // 6) If the local buffer runs out of data we should stuff the buffer with older
 //    frames.
 // 7) The system delay should within |kMaxConvergenceMs| ms heal from
 //    disturbances like drift, data glitches, toggling events and outliers.
 // 8) The system delay should never become negative.

 TEST_F(SystemDelayTest, CorrectIncreaseWhenBufferFarend) {
   // When we add data to the AEC buffer the internal system delay should be
   // incremented with the same amount as the size of data.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);

     // Loop through a couple of calls to make sure the system delay increments
     // correctly.
     for (int j = 1; j <= 5; j++) {
       EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
       EXPECT_EQ(j * samples_per_frame_, WebRtcAec_system_delay(self_->aec));
     }
   }
 }

 // TODO(bjornv): Add a test to verify behavior if the far-end buffer is full
 // when adding new data.

 TEST_F(SystemDelayTest, CorrectDelayAfterStableStartup) {
   // We run the system in a stable startup. After that we verify that the system
   // delay meets the requirements.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();

     // Verify system delay with respect to requirements, i.e., the
     // |system_delay| is in the interval [75%, 100%] of what's reported on the
     // average.
     int average_reported_delay = kDeviceBufMs * samples_per_frame_ / 10;
     EXPECT_GE(average_reported_delay, WebRtcAec_system_delay(self_->aec));
     EXPECT_LE(average_reported_delay * 3 / 4,
               WebRtcAec_system_delay(self_->aec));
   }
 }

 TEST_F(SystemDelayTest, CorrectDelayAfterUnstableStartup) {
   // In an unstable system we would start processing after |kMaxConvergenceMs|.
   // On the last frame the AEC buffer is adjusted to 60% of the last reported
   // device buffer size.
   // We construct an unstable system by altering the device buffer size between
   // two values |kDeviceBufMs| +- 25 ms.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);

     // To make sure we have a full buffer when we verify stability we first fill
     // up the far-end buffer with the same amount as we will report in on the
     // average through Process().
     int buffer_size = BufferFillUp();

     int buffer_offset_ms = 25;
     int reported_delay_ms = 0;
     int process_time_ms = 0;
     for (; process_time_ms <= kMaxConvergenceMs; process_time_ms += 10) {
       reported_delay_ms = kDeviceBufMs + buffer_offset_ms;
       RenderAndCapture(reported_delay_ms);
       buffer_size += samples_per_frame_;
       buffer_offset_ms = -buffer_offset_ms;
       if (self_->startup_phase == 0) {
         // We have left the startup phase.
         break;
       }
     }
     // Verify convergence time.
     EXPECT_GE(kMaxConvergenceMs, process_time_ms);
     // Verify that the buffer has been flushed.
     EXPECT_GE(buffer_size, WebRtcAec_system_delay(self_->aec));

     // Verify system delay with respect to requirements, i.e., the
     // |system_delay| is in the interval [60%, 100%] of what's last reported.
     EXPECT_GE(reported_delay_ms * samples_per_frame_ / 10,
               WebRtcAec_system_delay(self_->aec));
     EXPECT_LE(reported_delay_ms * samples_per_frame_ / 10 * 3 / 5,
               WebRtcAec_system_delay(self_->aec));
   }
 }

 TEST_F(SystemDelayTest, CorrectDelayAfterStableBufferBuildUp) {
   // In this test we start by establishing the device buffer size during stable
   // conditions, but with an empty internal far-end buffer. Once that is done we
   // verify that the system delay is increased correctly until we have reach an
   // internal buffer size of 75% of what's been reported.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);

     // We assume that running |kStableConvergenceMs| calls will put the
     // algorithm in a state where the device buffer size has been determined. We
     // can make that assumption since we have a separate stability test.
     int process_time_ms = 0;
     for (; process_time_ms < kStableConvergenceMs; process_time_ms += 10) {
       EXPECT_EQ(0,
                 WebRtcAec_Process(handle_,
                                   near_,
                                   NULL,
                                   out_,
                                   NULL,
                                   samples_per_frame_,
                                   kDeviceBufMs,
                                   0));
     }
     // Verify that a buffer size has been established.
     EXPECT_EQ(0, self_->checkBuffSize);

     // We now have established the required buffer size. Let us verify that we
     // fill up before leaving the startup phase for normal processing.
     int buffer_size = 0;
     int target_buffer_size = kDeviceBufMs * samples_per_frame_ / 10 * 3 / 4;
     process_time_ms = 0;
     for (; process_time_ms <= kMaxConvergenceMs; process_time_ms += 10) {
       RenderAndCapture(kDeviceBufMs);
       buffer_size += samples_per_frame_;
       if (self_->startup_phase == 0) {
         // We have left the startup phase.
         break;
       }
     }
     // Verify convergence time.
     EXPECT_GT(kMaxConvergenceMs, process_time_ms);
     // Verify that the buffer has reached the desired size.
     EXPECT_LE(target_buffer_size, WebRtcAec_system_delay(self_->aec));

     // Verify normal behavior (system delay is kept constant) after startup by
     // running a couple of calls to BufferFarend() and Process().
     for (int j = 0; j < 6; j++) {
       int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
       RenderAndCapture(kDeviceBufMs);
       EXPECT_EQ(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));
     }
   }
 }

 TEST_F(SystemDelayTest, CorrectDelayWhenBufferUnderrun) {
   // Here we test a buffer under run scenario. If we keep on calling
   // WebRtcAec_Process() we will finally run out of data, but should
   // automatically stuff the buffer. We verify this behavior by checking if the
   // system delay goes negative.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();

     // The AEC has now left the Startup phase. We now have at most
     // |kStableConvergenceMs| in the buffer. Keep on calling Process() until
     // we run out of data and verify that the system delay is non-negative.
     for (int j = 0; j <= kStableConvergenceMs; j += 10) {
       EXPECT_EQ(0,
                 WebRtcAec_Process(handle_,
                                   near_,
                                   NULL,
                                   out_,
                                   NULL,
                                   samples_per_frame_,
                                   kDeviceBufMs,
                                   0));
       EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
     }
   }
 }

 TEST_F(SystemDelayTest, CorrectDelayDuringDrift) {
   // This drift test should verify that the system delay is never exceeding the
   // device buffer. The drift is simulated by decreasing the reported device
   // buffer size by 1 ms every 100 ms. If the device buffer size goes below 30
   // ms we jump (add) 10 ms to give a repeated pattern.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();

     // We have now left the startup phase and proceed with normal processing.
     int jump = 0;
     for (int j = 0; j < 1000; j++) {
       // Drift = -1 ms per 100 ms of data.
       int device_buf_ms = kDeviceBufMs - (j / 10) + jump;
       int device_buf = MapBufferSizeToSamples(device_buf_ms);

       if (device_buf_ms < 30) {
         // Add 10 ms data, taking affect next frame.
         jump += 10;
       }
       RenderAndCapture(device_buf_ms);

       // Verify that the system delay does not exceed the device buffer.
       EXPECT_GE(device_buf, WebRtcAec_system_delay(self_->aec));

       // Verify that the system delay is non-negative.
       EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
     }
   }
 }

 TEST_F(SystemDelayTest, ShouldRecoverAfterGlitch) {
   // This glitch test should verify that the system delay recovers if there is
   // a glitch in data. The data glitch is constructed as 200 ms of buffering
   // after which the stable procedure continues. The glitch is never reported by
   // the device.
   // The system is said to be in a non-causal state if the difference between
   // the device buffer and system delay is less than a block (64 samples).
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();
     int device_buf = MapBufferSizeToSamples(kDeviceBufMs);
     // Glitch state.
     for (int j = 0; j < 20; j++) {
       EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
       // No need to verify system delay, since that is done in a separate test.
     }
     // Verify that we are in a non-causal state, i.e.,
     // |system_delay| > |device_buf|.
     EXPECT_LT(device_buf, WebRtcAec_system_delay(self_->aec));

     // Recover state. Should recover at least 4 ms of data per 10 ms, hence a
     // glitch of 200 ms will take at most 200 * 10 / 4 = 500 ms to recover from.
     bool non_causal = true;  // We are currently in a non-causal state.
     for (int j = 0; j < 50; j++) {
       int system_delay_before = WebRtcAec_system_delay(self_->aec);
       RenderAndCapture(kDeviceBufMs);
       int system_delay_after = WebRtcAec_system_delay(self_->aec);

       // We have recovered if |device_buf| - |system_delay_after| >= 64 (one
       // block). During recovery |system_delay_after| < |system_delay_before|,
       // otherwise they are equal.
       if (non_causal) {
         EXPECT_LT(system_delay_after, system_delay_before);
         if (device_buf - system_delay_after >= 64) {
           non_causal = false;
         }
       } else {
         EXPECT_EQ(system_delay_before, system_delay_after);
       }
       // Verify that the system delay is non-negative.
       EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
     }
     // Check that we have recovered.
     EXPECT_FALSE(non_causal);
   }
 }

 TEST_F(SystemDelayTest, UnaffectedWhenSpuriousDeviceBufferValues) {
   // This spurious device buffer data test aims at verifying that the system
   // delay is unaffected by large outliers.
   // The system is said to be in a non-causal state if the difference between
   // the device buffer and system delay is less than a block (64 samples).
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();
     int device_buf = MapBufferSizeToSamples(kDeviceBufMs);

     // Normal state. We are currently not in a non-causal state.
     bool non_causal = false;

     // Run 1 s and replace device buffer size with 500 ms every 100 ms.
     for (int j = 0; j < 100; j++) {
       int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
       int device_buf_ms = kDeviceBufMs;
       if (j % 10 == 0) {
         device_buf_ms = 500;
       }
       RenderAndCapture(device_buf_ms);

       // Check for non-causality.
       if (device_buf - WebRtcAec_system_delay(self_->aec) < 64) {
         non_causal = true;
       }
       EXPECT_FALSE(non_causal);
       EXPECT_EQ(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));

       // Verify that the system delay is non-negative.
       EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
     }
   }
 }

 TEST_F(SystemDelayTest, CorrectImpactWhenTogglingDeviceBufferValues) {
   // This test aims at verifying that the system delay is "unaffected" by
   // toggling values reported by the device.
   // The test is constructed such that every other device buffer value is zero
   // and then 2 * |kDeviceBufMs|, hence the size is constant on the average. The
   // zero values will force us into a non-causal state and thereby lowering the
   // system delay until we basically runs out of data. Once that happens the
   // buffer will be stuffed.
   // TODO(bjornv): This test will have a better impact if we verified that the
   // delay estimate goes up when the system delay goes done to meet the average
   // device buffer size.
   for (size_t i = 0; i < kNumSampleRates; i++) {
     Init(kSampleRateHz[i]);
     RunStableStartup();
     int device_buf = MapBufferSizeToSamples(kDeviceBufMs);

     // Normal state. We are currently not in a non-causal state.
     bool non_causal = false;

     // Loop through 100 frames (both render and capture), which equals 1 s of
     // data. Every odd frame we set the device buffer size to 2 * |kDeviceBufMs|
     // and even frames we set the device buffer size to zero.
     for (int j = 0; j < 100; j++) {
       int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
       int device_buf_ms = 2 * (j % 2) * kDeviceBufMs;
       RenderAndCapture(device_buf_ms);

       // Check for non-causality, compared with the average device buffer size.
       non_causal |= (device_buf - WebRtcAec_system_delay(self_->aec) < 64);
       EXPECT_GE(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));

       // Verify that the system delay is non-negative.
       EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
     }
     // Verify we are not in a non-causal state.
     EXPECT_FALSE(non_causal);
   }
 }

 }  // namespace
	/*
	* 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 "testing/gtest/include/gtest/gtest.h"

	extern "C" {
	#include "webrtc/modules/audio_processing/aec/aec_core.h"
	}
	#include "webrtc/modules/audio_processing/aec/echo_cancellation_internal.h"
	#include "webrtc/modules/audio_processing/aec/include/echo_cancellation.h"
	#include "webrtc/typedefs.h"

	namespace {

	class SystemDelayTest : public ::testing::Test {
	protected:
	SystemDelayTest();
	virtual void SetUp();
	virtual void TearDown();

	// Initialization of AEC handle with respect to \|sample_rate_hz\|. Since the
	// device sample rate is unimportant we set that value to 48000 Hz.
	void Init(int sample_rate_hz);

	// Makes one render call and one capture call in that specific order.
	void RenderAndCapture(int device_buffer_ms);

	// Fills up the far-end buffer with respect to the default device buffer size.
	int BufferFillUp();

	// Runs and verifies the behavior in a stable startup procedure.
	void RunStableStartup();

	// Maps buffer size in ms into samples, taking the unprocessed frame into
	// account.
	int MapBufferSizeToSamples(int size_in_ms);

	void* handle_;
	aecpc_t* self_;
	int samples_per_frame_;
	// Dummy input/output speech data.
	int16_t far_[160];
	int16_t near_[160];
	int16_t out_[160];
	};

	SystemDelayTest::SystemDelayTest()
	: handle_(NULL), self_(NULL), samples_per_frame_(0) {
	// Dummy input data are set with more or less arbitrary non-zero values.
	memset(far_, 1, sizeof(far_));
	memset(near_, 2, sizeof(near_));
	memset(out_, 0, sizeof(out_));
	}

	void SystemDelayTest::SetUp() {
	ASSERT_EQ(0, WebRtcAec_Create(&handle_));
	self_ = reinterpret_cast<aecpc_t*>(handle_);
	}

	void SystemDelayTest::TearDown() {
	// Free AEC
	ASSERT_EQ(0, WebRtcAec_Free(handle_));
	handle_ = NULL;
	}

	// In SWB mode nothing is added to the buffer handling with respect to
	// functionality compared to WB. We therefore only verify behavior in NB and WB.
	static const int kSampleRateHz[] = {8000, 16000};
	static const size_t kNumSampleRates =
	sizeof(kSampleRateHz) / sizeof(*kSampleRateHz);

	// Default audio device buffer size used.
	static const int kDeviceBufMs = 100;

	// Requirement for a stable device convergence time in ms. Should converge in
	// less than \|kStableConvergenceMs\|.
	static const int kStableConvergenceMs = 100;

	// Maximum convergence time in ms. This means that we should leave the startup
	// phase after \|kMaxConvergenceMs\| independent of device buffer stability
	// conditions.
	static const int kMaxConvergenceMs = 500;

	void SystemDelayTest::Init(int sample_rate_hz) {
	// Initialize AEC
	EXPECT_EQ(0, WebRtcAec_Init(handle_, sample_rate_hz, 48000));

	// One frame equals 10 ms of data.
	samples_per_frame_ = sample_rate_hz / 100;
	}

	void SystemDelayTest::RenderAndCapture(int device_buffer_ms) {
	EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
	EXPECT_EQ(0,
	WebRtcAec_Process(handle_,
	near_,
	NULL,
	out_,
	NULL,
	samples_per_frame_,
	device_buffer_ms,
	0));
	}

	int SystemDelayTest::BufferFillUp() {
	// To make sure we have a full buffer when we verify stability we first fill
	// up the far-end buffer with the same amount as we will report in through
	// Process().
	int buffer_size = 0;
	for (int i = 0; i < kDeviceBufMs / 10; i++) {
	EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
	buffer_size += samples_per_frame_;
	EXPECT_EQ(buffer_size, WebRtcAec_system_delay(self_->aec));
	}
	return buffer_size;
	}

	void SystemDelayTest::RunStableStartup() {
	// To make sure we have a full buffer when we verify stability we first fill
	// up the far-end buffer with the same amount as we will report in through
	// Process().
	int buffer_size = BufferFillUp();
	// A stable device should be accepted and put in a regular process mode within
	// \|kStableConvergenceMs\|.
	int process_time_ms = 0;
	for (; process_time_ms < kStableConvergenceMs; process_time_ms += 10) {
	RenderAndCapture(kDeviceBufMs);
	buffer_size += samples_per_frame_;
	if (self_->startup_phase == 0) {
	// We have left the startup phase.
	break;
	}
	}
	// Verify convergence time.
	EXPECT_GT(kStableConvergenceMs, process_time_ms);
	// Verify that the buffer has been flushed.
	EXPECT_GE(buffer_size, WebRtcAec_system_delay(self_->aec));
	}

	int SystemDelayTest::MapBufferSizeToSamples(int size_in_ms) {
	// The extra 10 ms corresponds to the unprocessed frame.
	return (size_in_ms + 10) * samples_per_frame_ / 10;
	}

	// The tests should meet basic requirements and not be adjusted to what is
	// actually implemented. If we don't get good code coverage this way we either
	// lack in tests or have unnecessary code.
	// General requirements:
	// 1) If we add far-end data the system delay should be increased with the same
	// amount we add.
	// 2) If the far-end buffer is full we should flush the oldest data to make room
	// for the new. In this case the system delay is unaffected.
	// 3) There should exist a startup phase in which the buffer size is to be
	// determined. In this phase no cancellation should be performed.
	// 4) Under stable conditions (small variations in device buffer sizes) the AEC
	// should determine an appropriate local buffer size within
	// \|kStableConvergenceMs\| ms.
	// 5) Under unstable conditions the AEC should make a decision within
	// \|kMaxConvergenceMs\| ms.
	// 6) If the local buffer runs out of data we should stuff the buffer with older
	// frames.
	// 7) The system delay should within \|kMaxConvergenceMs\| ms heal from
	// disturbances like drift, data glitches, toggling events and outliers.
	// 8) The system delay should never become negative.

	TEST_F(SystemDelayTest, CorrectIncreaseWhenBufferFarend) {
	// When we add data to the AEC buffer the internal system delay should be
	// incremented with the same amount as the size of data.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);

	// Loop through a couple of calls to make sure the system delay increments
	// correctly.
	for (int j = 1; j <= 5; j++) {
	EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
	EXPECT_EQ(j * samples_per_frame_, WebRtcAec_system_delay(self_->aec));
	}
	}
	}

	// TODO(bjornv): Add a test to verify behavior if the far-end buffer is full
	// when adding new data.

	TEST_F(SystemDelayTest, CorrectDelayAfterStableStartup) {
	// We run the system in a stable startup. After that we verify that the system
	// delay meets the requirements.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();

	// Verify system delay with respect to requirements, i.e., the
	// \|system_delay\| is in the interval [75%, 100%] of what's reported on the
	// average.
	int average_reported_delay = kDeviceBufMs * samples_per_frame_ / 10;
	EXPECT_GE(average_reported_delay, WebRtcAec_system_delay(self_->aec));
	EXPECT_LE(average_reported_delay * 3 / 4,
	WebRtcAec_system_delay(self_->aec));
	}
	}

	TEST_F(SystemDelayTest, CorrectDelayAfterUnstableStartup) {
	// In an unstable system we would start processing after \|kMaxConvergenceMs\|.
	// On the last frame the AEC buffer is adjusted to 60% of the last reported
	// device buffer size.
	// We construct an unstable system by altering the device buffer size between
	// two values \|kDeviceBufMs\| +- 25 ms.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);

	// To make sure we have a full buffer when we verify stability we first fill
	// up the far-end buffer with the same amount as we will report in on the
	// average through Process().
	int buffer_size = BufferFillUp();

	int buffer_offset_ms = 25;
	int reported_delay_ms = 0;
	int process_time_ms = 0;
	for (; process_time_ms <= kMaxConvergenceMs; process_time_ms += 10) {
	reported_delay_ms = kDeviceBufMs + buffer_offset_ms;
	RenderAndCapture(reported_delay_ms);
	buffer_size += samples_per_frame_;
	buffer_offset_ms = -buffer_offset_ms;
	if (self_->startup_phase == 0) {
	// We have left the startup phase.
	break;
	}
	}
	// Verify convergence time.
	EXPECT_GE(kMaxConvergenceMs, process_time_ms);
	// Verify that the buffer has been flushed.
	EXPECT_GE(buffer_size, WebRtcAec_system_delay(self_->aec));

	// Verify system delay with respect to requirements, i.e., the
	// \|system_delay\| is in the interval [60%, 100%] of what's last reported.
	EXPECT_GE(reported_delay_ms * samples_per_frame_ / 10,
	WebRtcAec_system_delay(self_->aec));
	EXPECT_LE(reported_delay_ms * samples_per_frame_ / 10 * 3 / 5,
	WebRtcAec_system_delay(self_->aec));
	}
	}

	TEST_F(SystemDelayTest, CorrectDelayAfterStableBufferBuildUp) {
	// In this test we start by establishing the device buffer size during stable
	// conditions, but with an empty internal far-end buffer. Once that is done we
	// verify that the system delay is increased correctly until we have reach an
	// internal buffer size of 75% of what's been reported.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);

	// We assume that running \|kStableConvergenceMs\| calls will put the
	// algorithm in a state where the device buffer size has been determined. We
	// can make that assumption since we have a separate stability test.
	int process_time_ms = 0;
	for (; process_time_ms < kStableConvergenceMs; process_time_ms += 10) {
	EXPECT_EQ(0,
	WebRtcAec_Process(handle_,
	near_,
	NULL,
	out_,
	NULL,
	samples_per_frame_,
	kDeviceBufMs,
	0));
	}
	// Verify that a buffer size has been established.
	EXPECT_EQ(0, self_->checkBuffSize);

	// We now have established the required buffer size. Let us verify that we
	// fill up before leaving the startup phase for normal processing.
	int buffer_size = 0;
	int target_buffer_size = kDeviceBufMs * samples_per_frame_ / 10 * 3 / 4;
	process_time_ms = 0;
	for (; process_time_ms <= kMaxConvergenceMs; process_time_ms += 10) {
	RenderAndCapture(kDeviceBufMs);
	buffer_size += samples_per_frame_;
	if (self_->startup_phase == 0) {
	// We have left the startup phase.
	break;
	}
	}
	// Verify convergence time.
	EXPECT_GT(kMaxConvergenceMs, process_time_ms);
	// Verify that the buffer has reached the desired size.
	EXPECT_LE(target_buffer_size, WebRtcAec_system_delay(self_->aec));

	// Verify normal behavior (system delay is kept constant) after startup by
	// running a couple of calls to BufferFarend() and Process().
	for (int j = 0; j < 6; j++) {
	int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
	RenderAndCapture(kDeviceBufMs);
	EXPECT_EQ(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));
	}
	}
	}

	TEST_F(SystemDelayTest, CorrectDelayWhenBufferUnderrun) {
	// Here we test a buffer under run scenario. If we keep on calling
	// WebRtcAec_Process() we will finally run out of data, but should
	// automatically stuff the buffer. We verify this behavior by checking if the
	// system delay goes negative.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();

	// The AEC has now left the Startup phase. We now have at most
	// \|kStableConvergenceMs\| in the buffer. Keep on calling Process() until
	// we run out of data and verify that the system delay is non-negative.
	for (int j = 0; j <= kStableConvergenceMs; j += 10) {
	EXPECT_EQ(0,
	WebRtcAec_Process(handle_,
	near_,
	NULL,
	out_,
	NULL,
	samples_per_frame_,
	kDeviceBufMs,
	0));
	EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
	}
	}
	}

	TEST_F(SystemDelayTest, CorrectDelayDuringDrift) {
	// This drift test should verify that the system delay is never exceeding the
	// device buffer. The drift is simulated by decreasing the reported device
	// buffer size by 1 ms every 100 ms. If the device buffer size goes below 30
	// ms we jump (add) 10 ms to give a repeated pattern.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();

	// We have now left the startup phase and proceed with normal processing.
	int jump = 0;
	for (int j = 0; j < 1000; j++) {
	// Drift = -1 ms per 100 ms of data.
	int device_buf_ms = kDeviceBufMs - (j / 10) + jump;
	int device_buf = MapBufferSizeToSamples(device_buf_ms);

	if (device_buf_ms < 30) {
	// Add 10 ms data, taking affect next frame.
	jump += 10;
	}
	RenderAndCapture(device_buf_ms);

	// Verify that the system delay does not exceed the device buffer.
	EXPECT_GE(device_buf, WebRtcAec_system_delay(self_->aec));

	// Verify that the system delay is non-negative.
	EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
	}
	}
	}

	TEST_F(SystemDelayTest, ShouldRecoverAfterGlitch) {
	// This glitch test should verify that the system delay recovers if there is
	// a glitch in data. The data glitch is constructed as 200 ms of buffering
	// after which the stable procedure continues. The glitch is never reported by
	// the device.
	// The system is said to be in a non-causal state if the difference between
	// the device buffer and system delay is less than a block (64 samples).
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();
	int device_buf = MapBufferSizeToSamples(kDeviceBufMs);
	// Glitch state.
	for (int j = 0; j < 20; j++) {
	EXPECT_EQ(0, WebRtcAec_BufferFarend(handle_, far_, samples_per_frame_));
	// No need to verify system delay, since that is done in a separate test.
	}
	// Verify that we are in a non-causal state, i.e.,
	// \|system_delay\| > \|device_buf\|.
	EXPECT_LT(device_buf, WebRtcAec_system_delay(self_->aec));

	// Recover state. Should recover at least 4 ms of data per 10 ms, hence a
	// glitch of 200 ms will take at most 200 * 10 / 4 = 500 ms to recover from.
	bool non_causal = true; // We are currently in a non-causal state.
	for (int j = 0; j < 50; j++) {
	int system_delay_before = WebRtcAec_system_delay(self_->aec);
	RenderAndCapture(kDeviceBufMs);
	int system_delay_after = WebRtcAec_system_delay(self_->aec);

	// We have recovered if \|device_buf\| - \|system_delay_after\| >= 64 (one
	// block). During recovery \|system_delay_after\| < \|system_delay_before\|,
	// otherwise they are equal.
	if (non_causal) {
	EXPECT_LT(system_delay_after, system_delay_before);
	if (device_buf - system_delay_after >= 64) {
	non_causal = false;
	}
	} else {
	EXPECT_EQ(system_delay_before, system_delay_after);
	}
	// Verify that the system delay is non-negative.
	EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
	}
	// Check that we have recovered.
	EXPECT_FALSE(non_causal);
	}
	}

	TEST_F(SystemDelayTest, UnaffectedWhenSpuriousDeviceBufferValues) {
	// This spurious device buffer data test aims at verifying that the system
	// delay is unaffected by large outliers.
	// The system is said to be in a non-causal state if the difference between
	// the device buffer and system delay is less than a block (64 samples).
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();
	int device_buf = MapBufferSizeToSamples(kDeviceBufMs);

	// Normal state. We are currently not in a non-causal state.
	bool non_causal = false;

	// Run 1 s and replace device buffer size with 500 ms every 100 ms.
	for (int j = 0; j < 100; j++) {
	int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
	int device_buf_ms = kDeviceBufMs;
	if (j % 10 == 0) {
	device_buf_ms = 500;
	}
	RenderAndCapture(device_buf_ms);

	// Check for non-causality.
	if (device_buf - WebRtcAec_system_delay(self_->aec) < 64) {
	non_causal = true;
	}
	EXPECT_FALSE(non_causal);
	EXPECT_EQ(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));

	// Verify that the system delay is non-negative.
	EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
	}
	}
	}

	TEST_F(SystemDelayTest, CorrectImpactWhenTogglingDeviceBufferValues) {
	// This test aims at verifying that the system delay is "unaffected" by
	// toggling values reported by the device.
	// The test is constructed such that every other device buffer value is zero
	// and then 2 * \|kDeviceBufMs\|, hence the size is constant on the average. The
	// zero values will force us into a non-causal state and thereby lowering the
	// system delay until we basically runs out of data. Once that happens the
	// buffer will be stuffed.
	// TODO(bjornv): This test will have a better impact if we verified that the
	// delay estimate goes up when the system delay goes done to meet the average
	// device buffer size.
	for (size_t i = 0; i < kNumSampleRates; i++) {
	Init(kSampleRateHz[i]);
	RunStableStartup();
	int device_buf = MapBufferSizeToSamples(kDeviceBufMs);

	// Normal state. We are currently not in a non-causal state.
	bool non_causal = false;

	// Loop through 100 frames (both render and capture), which equals 1 s of
	// data. Every odd frame we set the device buffer size to 2 * \|kDeviceBufMs\|
	// and even frames we set the device buffer size to zero.
	for (int j = 0; j < 100; j++) {
	int system_delay_before_calls = WebRtcAec_system_delay(self_->aec);
	int device_buf_ms = 2 * (j % 2) * kDeviceBufMs;
	RenderAndCapture(device_buf_ms);

	// Check for non-causality, compared with the average device buffer size.
	non_causal \|= (device_buf - WebRtcAec_system_delay(self_->aec) < 64);
	EXPECT_GE(system_delay_before_calls, WebRtcAec_system_delay(self_->aec));

	// Verify that the system delay is non-negative.
	EXPECT_LE(0, WebRtcAec_system_delay(self_->aec));
	}
	// Verify we are not in a non-causal state.
	EXPECT_FALSE(non_causal);
	}
	}

	} // namespace