webrtc之视频捕获模块--video_capture

webrtc的video_capture模块，为我们在不同端设备上采集视频提供了一个跨平台封装的视频采集功能,如下图中的webrtc的video_capture源码，现webrtc的video_capture模块支持android、ios、linux、mac和windows各操作平台下的视频采集，  我们在不同端设备上开发视频直播的时刻，也可以使用该模块进行视频采集。

该视频采集模块的库头文件为：

class VideoCaptureModule: public RefCountedModule {
 public:
  // Interface for receiving information about available camera devices.
  class DeviceInfo {
   public:
    virtual uint32_t NumberOfDevices() = 0;

    // Returns the available capture devices.
    // deviceNumber   - Index of capture device.
    // deviceNameUTF8 - Friendly name of the capture device.
    // deviceUniqueIdUTF8 - Unique name of the capture device if it exist.
    //                      Otherwise same as deviceNameUTF8.
    // productUniqueIdUTF8 - Unique product id if it exist.
    //                       Null terminated otherwise.
    virtual int32_t GetDeviceName(
        uint32_t deviceNumber,
        char* deviceNameUTF8,
        uint32_t deviceNameLength,
        char* deviceUniqueIdUTF8,
        uint32_t deviceUniqueIdUTF8Length,
        char* productUniqueIdUTF8 = 0,
        uint32_t productUniqueIdUTF8Length = 0) = 0;

    // Returns the number of capabilities this device.
    virtual int32_t NumberOfCapabilities(
        const char* deviceUniqueIdUTF8) = 0;

    // Gets the capabilities of the named device.
    virtual int32_t GetCapability(
        const char* deviceUniqueIdUTF8,
        const uint32_t deviceCapabilityNumber,
        VideoCaptureCapability& capability) = 0;

    // Gets clockwise angle the captured frames should be rotated in order
    // to be displayed correctly on a normally rotated display.
    virtual int32_t GetOrientation(
        const char* deviceUniqueIdUTF8,
        VideoCaptureRotation& orientation) = 0;

    // Gets the capability that best matches the requested width, height and
    // frame rate.
    // Returns the deviceCapabilityNumber on success.
    virtual int32_t GetBestMatchedCapability(
        const char* deviceUniqueIdUTF8,
        const VideoCaptureCapability& requested,
        VideoCaptureCapability& resulting) = 0;

     // Display OS /capture device specific settings dialog
    virtual int32_t DisplayCaptureSettingsDialogBox(
        const char* deviceUniqueIdUTF8,
        const char* dialogTitleUTF8,
        void* parentWindow,
        uint32_t positionX,
        uint32_t positionY) = 0;

    virtual ~DeviceInfo() {}
  };

  class VideoCaptureEncodeInterface {
   public:
    virtual int32_t ConfigureEncoder(const VideoCodec& codec,
                                     uint32_t maxPayloadSize) = 0;
    // Inform the encoder about the new target bit rate.
    //  - newBitRate       : New target bit rate in Kbit/s.
    //  - frameRate        : The target frame rate.
    virtual int32_t SetRates(int32_t newBitRate, int32_t frameRate) = 0;
    // Inform the encoder about the packet loss and the round-trip time.
    //   - packetLoss   : Fraction lost
    //                    (loss rate in percent = 100 * packetLoss / 255).
    //   - rtt          : Round-trip time in milliseconds.
    virtual int32_t SetChannelParameters(uint32_t packetLoss, int rtt) = 0;

    // Encode the next frame as key frame.
    virtual int32_t EncodeFrameType(const FrameType type) = 0;
  protected:
    virtual ~VideoCaptureEncodeInterface() {
    }
  };

  //   Register capture data callback
  virtual int32_t RegisterCaptureDataCallback(
      VideoCaptureDataCallback& dataCallback) = 0;

  //  Remove capture data callback
  virtual int32_t DeRegisterCaptureDataCallback() = 0;

  // Register capture callback.
  virtual int32_t RegisterCaptureCallback(
      VideoCaptureFeedBack& callBack) = 0;

  //  Remove capture callback.
  virtual int32_t DeRegisterCaptureCallback() = 0;

  // Start capture device
  virtual int32_t StartCapture(
      const VideoCaptureCapability& capability) = 0;

  virtual int32_t StopCapture() = 0;

  // Returns the name of the device used by this module.
  virtual const char* CurrentDeviceName() const = 0;

  // Returns true if the capture device is running
  virtual bool CaptureStarted() = 0;

  // Gets the current configuration.
  virtual int32_t CaptureSettings(VideoCaptureCapability& settings) = 0;

  virtual int32_t SetCaptureDelay(int32_t delayMS) = 0;

  // Returns the current CaptureDelay. Only valid when the camera is running.
  virtual int32_t CaptureDelay() = 0;

  // Set the rotation of the captured frames.
  // If the rotation is set to the same as returned by
  // DeviceInfo::GetOrientation the captured frames are
  // displayed correctly if rendered.
  virtual int32_t SetCaptureRotation(VideoCaptureRotation rotation) = 0;

  // Gets a pointer to an encode interface if the capture device supports the
  // requested type and size.  NULL otherwise.
  virtual VideoCaptureEncodeInterface* GetEncodeInterface(
      const VideoCodec& codec) = 0;

  virtual int32_t EnableFrameRateCallback(const bool enable) = 0;
  virtual int32_t EnableNoPictureAlarm(const bool enable) = 0;

protected:
  virtual ~VideoCaptureModule() {};
};

　　

其中包括一个设备信息类（class DeviceInfo）和一个采集视频的编码接口类（class VideoCaptureEncodeInterface）：class DeviceInfo是用来管理处理视频设备信息，而class VideoCaptureEncodeInterface是用来配置采集的帧编码格式信息。

类 VideoCaptureModule  中的函数virtual int32_t StartCapture （const VideoCaptureCapability& capability) = 0; 用于启动采集视频，而virtual int32_t StopCapture() = 0;用于停止采集视频。

我们可以看到该模块采用了一个策略的适配器模式，提供视频采集的基本函数封装了几个端的视频采集方式。

关于该模块的单独使用，我们可以参考test下对应文件（.mm是对应mac系统），如下图：

如下为video_capture_unittest.cc 的源码：

/*
 *  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 <stdio.h>

#include "testing/gtest/include/gtest/gtest.h"
#include "webrtc/common_video/interface/i420_video_frame.h"
#include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
#include "webrtc/modules/utility/interface/process_thread.h"
#include "webrtc/modules/video_capture/include/video_capture.h"
#include "webrtc/modules/video_capture/include/video_capture_factory.h"
#include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
#include "webrtc/system_wrappers/interface/scoped_ptr.h"
#include "webrtc/system_wrappers/interface/scoped_refptr.h"
#include "webrtc/system_wrappers/interface/sleep.h"
#include "webrtc/system_wrappers/interface/tick_util.h"

using webrtc::CriticalSectionWrapper;
using webrtc::CriticalSectionScoped;
using webrtc::scoped_ptr;
using webrtc::SleepMs;
using webrtc::TickTime;
using webrtc::VideoCaptureAlarm;
using webrtc::VideoCaptureCapability;
using webrtc::VideoCaptureDataCallback;
using webrtc::VideoCaptureFactory;
using webrtc::VideoCaptureFeedBack;
using webrtc::VideoCaptureModule;

#define WAIT_(ex, timeout, res) \
  do { \
    res = (ex); \
    int64_t start = TickTime::MillisecondTimestamp(); \
    while (!res && TickTime::MillisecondTimestamp() < start + timeout) { \
      SleepMs(5); \
      res = (ex); \
    } \
  } while (0);\

#define EXPECT_TRUE_WAIT(ex, timeout) \
  do { \
    bool res; \
    WAIT_(ex, timeout, res); \
    if (!res) EXPECT_TRUE(ex); \
  } while (0);

static const int kTimeOut = 5000;
static const int kTestHeight = 288;
static const int kTestWidth = 352;
static const int kTestFramerate = 30;

// Compares the content of two video frames.
static bool CompareFrames(const webrtc::I420VideoFrame& frame1,
                          const webrtc::I420VideoFrame& frame2) {
  bool result =
      (frame1.stride(webrtc::kYPlane) == frame2.stride(webrtc::kYPlane)) &&
      (frame1.stride(webrtc::kUPlane) == frame2.stride(webrtc::kUPlane)) &&
      (frame1.stride(webrtc::kVPlane) == frame2.stride(webrtc::kVPlane)) &&
      (frame1.width() == frame2.width()) &&
      (frame1.height() == frame2.height());

  if (!result)
    return false;
  for (int plane = 0; plane < webrtc::kNumOfPlanes; plane ++) {
      webrtc::PlaneType plane_type = static_cast<webrtc::PlaneType>(plane);
      int allocated_size1 = frame1.allocated_size(plane_type);
      int allocated_size2 = frame2.allocated_size(plane_type);
      if (allocated_size1 != allocated_size2)
        return false;
      const uint8_t* plane_buffer1 = frame1.buffer(plane_type);
      const uint8_t* plane_buffer2 = frame2.buffer(plane_type);
      if (memcmp(plane_buffer1, plane_buffer2, allocated_size1))
        return false;
    }
    return true;
}

class TestVideoCaptureCallback : public VideoCaptureDataCallback {
 public:
  TestVideoCaptureCallback()
    : capture_cs_(CriticalSectionWrapper::CreateCriticalSection()),
      capture_delay_(-1),
      last_render_time_ms_(0),
      incoming_frames_(0),
      timing_warnings_(0),
      rotate_frame_(webrtc::kCameraRotate0){
  }

  ~TestVideoCaptureCallback() {
    if (timing_warnings_ > 0)
      printf("No of timing warnings %d\n", timing_warnings_);
  }

  virtual void OnIncomingCapturedFrame(const int32_t id,
                                       webrtc::I420VideoFrame& videoFrame) {
    CriticalSectionScoped cs(capture_cs_.get());

    int height = videoFrame.height();
    int width = videoFrame.width();
    if (rotate_frame_ == webrtc::kCameraRotate90 ||
        rotate_frame_ == webrtc::kCameraRotate270) {
      EXPECT_EQ(width, capability_.height);
      EXPECT_EQ(height, capability_.width);
    } else {
      EXPECT_EQ(height, capability_.height);
      EXPECT_EQ(width, capability_.width);
    }
    // RenderTimstamp should be the time now.
    EXPECT_TRUE(
        videoFrame.render_time_ms() >= TickTime::MillisecondTimestamp()-30 &&
        videoFrame.render_time_ms() <= TickTime::MillisecondTimestamp());

    if ((videoFrame.render_time_ms() >
            last_render_time_ms_ + (1000 * 1.1) / capability_.maxFPS &&
            last_render_time_ms_ > 0) ||
        (videoFrame.render_time_ms() <
            last_render_time_ms_ + (1000 * 0.9) / capability_.maxFPS &&
            last_render_time_ms_ > 0)) {
      timing_warnings_++;
    }

    incoming_frames_++;
    last_render_time_ms_ = videoFrame.render_time_ms();
    last_frame_.CopyFrame(videoFrame);
  }
  virtual void OnIncomingCapturedEncodedFrame(const int32_t id,
                                              webrtc::VideoFrame& videoFrame,
                                              webrtc::VideoCodecType codecType)
 {
     assert(false);
 }

  virtual void OnCaptureDelayChanged(const int32_t id,
                                     const int32_t delay) {
    CriticalSectionScoped cs(capture_cs_.get());
    capture_delay_ = delay;
  }

  void SetExpectedCapability(VideoCaptureCapability capability) {
    CriticalSectionScoped cs(capture_cs_.get());
    capability_= capability;
    incoming_frames_ = 0;
    last_render_time_ms_ = 0;
    capture_delay_ = -1;
  }
  int incoming_frames() {
    CriticalSectionScoped cs(capture_cs_.get());
    return incoming_frames_;
  }

  int capture_delay() {
    CriticalSectionScoped cs(capture_cs_.get());
    return capture_delay_;
  }
  int timing_warnings() {
    CriticalSectionScoped cs(capture_cs_.get());
    return timing_warnings_;
  }
  VideoCaptureCapability capability() {
    CriticalSectionScoped cs(capture_cs_.get());
    return capability_;
  }

  bool CompareLastFrame(const webrtc::I420VideoFrame& frame) {
    CriticalSectionScoped cs(capture_cs_.get());
    return CompareFrames(last_frame_, frame);
  }

  void SetExpectedCaptureRotation(webrtc::VideoCaptureRotation rotation) {
    CriticalSectionScoped cs(capture_cs_.get());
    rotate_frame_ = rotation;
  }

 private:
  scoped_ptr<CriticalSectionWrapper> capture_cs_;
  VideoCaptureCapability capability_;
  int capture_delay_;
  int64_t last_render_time_ms_;
  int incoming_frames_;
  int timing_warnings_;
  webrtc::I420VideoFrame last_frame_;
  webrtc::VideoCaptureRotation rotate_frame_;
};

class TestVideoCaptureFeedBack : public VideoCaptureFeedBack {
 public:
  TestVideoCaptureFeedBack() :
    capture_cs_(CriticalSectionWrapper::CreateCriticalSection()),
    frame_rate_(0),
    alarm_(webrtc::Cleared) {
  }

  virtual void OnCaptureFrameRate(const int32_t id,
                                  const uint32_t frameRate) {
    CriticalSectionScoped cs(capture_cs_.get());
    frame_rate_ = frameRate;
  }

  virtual void OnNoPictureAlarm(const int32_t id,
                                const VideoCaptureAlarm reported_alarm) {
    CriticalSectionScoped cs(capture_cs_.get());
    alarm_ = reported_alarm;
  }
  int frame_rate() {
    CriticalSectionScoped cs(capture_cs_.get());
    return frame_rate_;

  }
  VideoCaptureAlarm alarm() {
    CriticalSectionScoped cs(capture_cs_.get());
    return alarm_;
  }

 private:
  scoped_ptr<CriticalSectionWrapper> capture_cs_;
  unsigned int frame_rate_;
  VideoCaptureAlarm alarm_;
};

class VideoCaptureTest : public testing::Test {
 public:
  VideoCaptureTest() : number_of_devices_(0) {}

  void SetUp() {
    device_info_.reset(VideoCaptureFactory::CreateDeviceInfo(5));
    number_of_devices_ = device_info_->NumberOfDevices();
    ASSERT_GT(number_of_devices_, 0u);
  }

  webrtc::scoped_refptr<VideoCaptureModule> OpenVideoCaptureDevice(
      unsigned int device,
      VideoCaptureDataCallback* callback) {
    char device_name[256];
    char unique_name[256];

    EXPECT_EQ(0, device_info_->GetDeviceName(
        device, device_name, 256, unique_name, 256));

    webrtc::scoped_refptr<VideoCaptureModule> module(
        VideoCaptureFactory::Create(device, unique_name));
    if (module.get() == NULL)
      return NULL;

    EXPECT_FALSE(module->CaptureStarted());

    EXPECT_EQ(0, module->RegisterCaptureDataCallback(*callback));
    return module;
  }

  void StartCapture(VideoCaptureModule* capture_module,
                    VideoCaptureCapability capability) {
    EXPECT_EQ(0, capture_module->StartCapture(capability));
    EXPECT_TRUE(capture_module->CaptureStarted());

    VideoCaptureCapability resulting_capability;
    EXPECT_EQ(0, capture_module->CaptureSettings(resulting_capability));
    EXPECT_EQ(capability.width, resulting_capability.width);
    EXPECT_EQ(capability.height, resulting_capability.height);
  }

  scoped_ptr<VideoCaptureModule::DeviceInfo> device_info_;
  unsigned int number_of_devices_;
};

TEST_F(VideoCaptureTest, CreateDelete) {
  for (int i = 0; i < 5; ++i) {
    int64_t start_time = TickTime::MillisecondTimestamp();
    TestVideoCaptureCallback capture_observer;
    webrtc::scoped_refptr<VideoCaptureModule> module(OpenVideoCaptureDevice(
        0, &capture_observer));
    ASSERT_TRUE(module.get() != NULL);

    VideoCaptureCapability capability;
#ifndef WEBRTC_MAC
    device_info_->GetCapability(module->CurrentDeviceName(), 0, capability);
#else
    capability.width = kTestWidth;
    capability.height = kTestHeight;
    capability.maxFPS = kTestFramerate;
    capability.rawType = webrtc::kVideoUnknown;
#endif
    capture_observer.SetExpectedCapability(capability);
    StartCapture(module.get(), capability);

    // Less than 4s to start the camera.
    EXPECT_LE(TickTime::MillisecondTimestamp() - start_time, 4000);

    // Make sure 5 frames are captured.
    EXPECT_TRUE_WAIT(capture_observer.incoming_frames() >= 5, kTimeOut);

    EXPECT_GE(capture_observer.capture_delay(), 0);

    int64_t stop_time = TickTime::MillisecondTimestamp();
    EXPECT_EQ(0, module->StopCapture());
    EXPECT_FALSE(module->CaptureStarted());

    // Less than 3s to stop the camera.
    EXPECT_LE(TickTime::MillisecondTimestamp() - stop_time, 3000);
  }
}

TEST_F(VideoCaptureTest, Capabilities) {
#ifdef WEBRTC_MAC
  printf("Video capture capabilities are not supported on Mac.\n");
  return;
#endif

  TestVideoCaptureCallback capture_observer;

  webrtc::scoped_refptr<VideoCaptureModule> module(OpenVideoCaptureDevice(
          0, &capture_observer));
  ASSERT_TRUE(module.get() != NULL);

  int number_of_capabilities = device_info_->NumberOfCapabilities(
      module->CurrentDeviceName());
  EXPECT_GT(number_of_capabilities, 0);
  for (int i = 0; i < number_of_capabilities; ++i) {
    VideoCaptureCapability capability;
    EXPECT_EQ(0, device_info_->GetCapability(module->CurrentDeviceName(), i,
                                             capability));
    capture_observer.SetExpectedCapability(capability);
    StartCapture(module.get(), capability);
    // Make sure 5 frames are captured.
    EXPECT_TRUE_WAIT(capture_observer.incoming_frames() >= 5, kTimeOut);

    EXPECT_EQ(0, module->StopCapture());
  }
}

// NOTE: flaky, crashes sometimes.
// http://code.google.com/p/webrtc/issues/detail?id=777
TEST_F(VideoCaptureTest, DISABLED_TestTwoCameras) {
  if (number_of_devices_ < 2) {
    printf("There are not two cameras available. Aborting test. \n");
    return;
  }

  TestVideoCaptureCallback capture_observer1;
  webrtc::scoped_refptr<VideoCaptureModule> module1(OpenVideoCaptureDevice(
          0, &capture_observer1));
  ASSERT_TRUE(module1.get() != NULL);
  VideoCaptureCapability capability1;
#ifndef WEBRTC_MAC
  device_info_->GetCapability(module1->CurrentDeviceName(), 0, capability1);
#else
  capability1.width = kTestWidth;
  capability1.height = kTestHeight;
  capability1.maxFPS = kTestFramerate;
  capability1.rawType = webrtc::kVideoUnknown;
#endif
  capture_observer1.SetExpectedCapability(capability1);

  TestVideoCaptureCallback capture_observer2;
  webrtc::scoped_refptr<VideoCaptureModule> module2(OpenVideoCaptureDevice(
          1, &capture_observer2));
  ASSERT_TRUE(module1.get() != NULL);

  VideoCaptureCapability capability2;
#ifndef WEBRTC_MAC
  device_info_->GetCapability(module2->CurrentDeviceName(), 0, capability2);
#else
  capability2.width = kTestWidth;
  capability2.height = kTestHeight;
  capability2.maxFPS = kTestFramerate;
  capability2.rawType = webrtc::kVideoUnknown;
#endif
  capture_observer2.SetExpectedCapability(capability2);

  StartCapture(module1.get(), capability1);
  StartCapture(module2.get(), capability2);
  EXPECT_TRUE_WAIT(capture_observer1.incoming_frames() >= 5, kTimeOut);
  EXPECT_TRUE_WAIT(capture_observer2.incoming_frames() >= 5, kTimeOut);
}

// Test class for testing external capture and capture feedback information
// such as frame rate and picture alarm.
class VideoCaptureExternalTest : public testing::Test {
 public:
  void SetUp() {
    capture_module_ = VideoCaptureFactory::Create(0, capture_input_interface_);
    process_module_ = webrtc::ProcessThread::CreateProcessThread();
    process_module_->Start();
    process_module_->RegisterModule(capture_module_);

    VideoCaptureCapability capability;
    capability.width = kTestWidth;
    capability.height = kTestHeight;
    capability.rawType = webrtc::kVideoYV12;
    capability.maxFPS = kTestFramerate;
    capture_callback_.SetExpectedCapability(capability);

    test_frame_.CreateEmptyFrame(kTestWidth, kTestHeight, kTestWidth,
                                 ((kTestWidth + 1) / 2), (kTestWidth + 1) / 2);
    SleepMs(1); // Wait 1ms so that two tests can't have the same timestamp.
    memset(test_frame_.buffer(webrtc::kYPlane), 127, kTestWidth * kTestHeight);
    memset(test_frame_.buffer(webrtc::kUPlane), 127,
           ((kTestWidth + 1) / 2) * ((kTestHeight + 1) / 2));
    memset(test_frame_.buffer(webrtc::kVPlane), 127,
           ((kTestWidth + 1) / 2) * ((kTestHeight + 1) / 2));

    EXPECT_EQ(0, capture_module_->RegisterCaptureDataCallback(
        capture_callback_));
    EXPECT_EQ(0, capture_module_->RegisterCaptureCallback(capture_feedback_));
    EXPECT_EQ(0, capture_module_->EnableFrameRateCallback(true));
    EXPECT_EQ(0, capture_module_->EnableNoPictureAlarm(true));
  }

  void TearDown() {
    process_module_->Stop();
    webrtc::ProcessThread::DestroyProcessThread(process_module_);
  }

  webrtc::VideoCaptureExternal* capture_input_interface_;
  webrtc::scoped_refptr<VideoCaptureModule> capture_module_;
  webrtc::ProcessThread* process_module_;
  webrtc::I420VideoFrame test_frame_;
  TestVideoCaptureCallback capture_callback_;
  TestVideoCaptureFeedBack capture_feedback_;
};

// Test input of external video frames.
TEST_F(VideoCaptureExternalTest, TestExternalCapture) {
  unsigned int length = webrtc::CalcBufferSize(webrtc::kI420,
                                               test_frame_.width(),
                                               test_frame_.height());
  webrtc::scoped_array<uint8_t> test_buffer(new uint8_t[length]);
  webrtc::ExtractBuffer(test_frame_, length, test_buffer.get());
  EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
      length, capture_callback_.capability(), 0));
  EXPECT_TRUE(capture_callback_.CompareLastFrame(test_frame_));
}

// Test input of planar I420 frames.
// NOTE: flaky, sometimes fails on the last CompareLastFrame.
// http://code.google.com/p/webrtc/issues/detail?id=777
TEST_F(VideoCaptureExternalTest, DISABLED_TestExternalCaptureI420) {
  webrtc::I420VideoFrame frame_i420;
  frame_i420.CopyFrame(test_frame_);

  EXPECT_EQ(0,
            capture_input_interface_->IncomingI420VideoFrame(&frame_i420, 0));
  EXPECT_TRUE(capture_callback_.CompareLastFrame(frame_i420));

  // Test with a frame with pitch not equal to width
  memset(test_frame_.buffer(webrtc::kYPlane), 0xAA,
         test_frame_.allocated_size(webrtc::kYPlane));
  memset(test_frame_.buffer(webrtc::kUPlane), 0xAA,
         test_frame_.allocated_size(webrtc::kUPlane));
  memset(test_frame_.buffer(webrtc::kVPlane), 0xAA,
         test_frame_.allocated_size(webrtc::kVPlane));
  webrtc::I420VideoFrame aligned_test_frame;
  int y_pitch = kTestWidth + 2;
  int u_pitch = kTestWidth / 2 + 1;
  int v_pitch = u_pitch;
  aligned_test_frame.CreateEmptyFrame(kTestWidth, kTestHeight,
                                      y_pitch, u_pitch, v_pitch);
  memset(aligned_test_frame.buffer(webrtc::kYPlane), 0,
         kTestWidth * kTestHeight);
  memset(aligned_test_frame.buffer(webrtc::kUPlane), 0,
         (kTestWidth + 1) / 2  * (kTestHeight + 1) / 2);
  memset(aligned_test_frame.buffer(webrtc::kVPlane), 0,
         (kTestWidth + 1) / 2  * (kTestHeight + 1) / 2);
  // Copy the test_frame_ to aligned_test_frame.
  int y_width = kTestWidth;
  int uv_width = kTestWidth / 2;
  int y_rows = kTestHeight;
  int uv_rows = kTestHeight / 2;
  unsigned char* y_plane = test_frame_.buffer(webrtc::kYPlane);
  unsigned char* u_plane = test_frame_.buffer(webrtc::kUPlane);
  unsigned char* v_plane = test_frame_.buffer(webrtc::kVPlane);
  // Copy Y
  unsigned char* current_pointer = aligned_test_frame.buffer(webrtc::kYPlane);
  for (int i = 0; i < y_rows; ++i) {
    memcpy(current_pointer, y_plane, y_width);
    // Remove the alignment which ViE doesn't support.
    current_pointer += y_pitch;
    y_plane += y_width;
  }
  // Copy U
  current_pointer = aligned_test_frame.buffer(webrtc::kUPlane);
  for (int i = 0; i < uv_rows; ++i) {
    memcpy(current_pointer, u_plane, uv_width);
    // Remove the alignment which ViE doesn't support.
    current_pointer += u_pitch;
    u_plane += uv_width;
  }
  // Copy V
  current_pointer = aligned_test_frame.buffer(webrtc::kVPlane);
  for (int i = 0; i < uv_rows; ++i) {
    memcpy(current_pointer, v_plane, uv_width);
    // Remove the alignment which ViE doesn't support.
    current_pointer += v_pitch;
    v_plane += uv_width;
  }
  frame_i420.CopyFrame(aligned_test_frame);

  EXPECT_EQ(0,
            capture_input_interface_->IncomingI420VideoFrame(&frame_i420, 0));
  EXPECT_TRUE(capture_callback_.CompareLastFrame(test_frame_));
}

// Test frame rate and no picture alarm.
TEST_F(VideoCaptureExternalTest , FrameRate) {
  int64_t testTime = 3;
  TickTime startTime = TickTime::Now();

  while ((TickTime::Now() - startTime).Milliseconds() < testTime * 1000) {
     unsigned int length = webrtc::CalcBufferSize(webrtc::kI420,
                                                 test_frame_.width(),
                                                 test_frame_.height());
     webrtc::scoped_array<uint8_t> test_buffer(new uint8_t[length]);
     webrtc::ExtractBuffer(test_frame_, length, test_buffer.get());
     EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
       length, capture_callback_.capability(), 0));
    SleepMs(100);
  }
  EXPECT_TRUE(capture_feedback_.frame_rate() >= 8 &&
              capture_feedback_.frame_rate() <= 10);
  SleepMs(500);
  EXPECT_EQ(webrtc::Raised, capture_feedback_.alarm());

  startTime = TickTime::Now();
  while ((TickTime::Now() - startTime).Milliseconds() < testTime * 1000) {
    unsigned int length = webrtc::CalcBufferSize(webrtc::kI420,
                                                 test_frame_.width(),
                                                 test_frame_.height());
    webrtc::scoped_array<uint8_t> test_buffer(new uint8_t[length]);
    webrtc::ExtractBuffer(test_frame_, length, test_buffer.get());
    EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
      length, capture_callback_.capability(), 0));
    SleepMs(1000 / 30);
  }
  EXPECT_EQ(webrtc::Cleared, capture_feedback_.alarm());
  // Frame rate might be less than 33 since we have paused providing
  // frames for a while.
  EXPECT_TRUE(capture_feedback_.frame_rate() >= 25 &&
              capture_feedback_.frame_rate() <= 33);
}

TEST_F(VideoCaptureExternalTest, Rotation) {
  EXPECT_EQ(0, capture_module_->SetCaptureRotation(webrtc::kCameraRotate0));
  unsigned int length = webrtc::CalcBufferSize(webrtc::kI420,
                                               test_frame_.width(),
                                               test_frame_.height());
  webrtc::scoped_array<uint8_t> test_buffer(new uint8_t[length]);
  webrtc::ExtractBuffer(test_frame_, length, test_buffer.get());
  EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
    length, capture_callback_.capability(), 0));
  EXPECT_EQ(0, capture_module_->SetCaptureRotation(webrtc::kCameraRotate90));
  capture_callback_.SetExpectedCaptureRotation(webrtc::kCameraRotate90);
  EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
    length, capture_callback_.capability(), 0));
  EXPECT_EQ(0, capture_module_->SetCaptureRotation(webrtc::kCameraRotate180));
  capture_callback_.SetExpectedCaptureRotation(webrtc::kCameraRotate180);
  EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
    length, capture_callback_.capability(), 0));
  EXPECT_EQ(0, capture_module_->SetCaptureRotation(webrtc::kCameraRotate270));
  capture_callback_.SetExpectedCaptureRotation(webrtc::kCameraRotate270);
  EXPECT_EQ(0, capture_input_interface_->IncomingFrame(test_buffer.get(),
    length, capture_callback_.capability(), 0));
}