1 files changed, 760 insertions, 0 deletions
diff --git a/dom/media/systemservices/video_engine/desktop_capture_impl.cc b/dom/media/systemservices/video_engine/desktop_capture_impl.cc
new file mode 100644
index 0000000000..fd88433cfa
--- /dev/null
+++ b/dom/media/systemservices/video_engine/desktop_capture_impl.cc
@@ -0,0 +1,760 @@
+/*
+ *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/video_capture/video_capture_impl.h"
+
+#include <stdlib.h>
+#include <memory>
+#include <string>
+
+#include "CamerasTypes.h"
+#include "PerformanceRecorder.h"
+
+#include "api/video/i420_buffer.h"
+#include "base/scoped_nsautorelease_pool.h"
+#include "common_video/libyuv/include/webrtc_libyuv.h"
+#include "libyuv.h"  // NOLINT
+#include "modules/include/module_common_types.h"
+#include "modules/video_capture/video_capture_config.h"
+#include "system_wrappers/include/clock.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/ref_counted_object.h"
+#include "rtc_base/time_utils.h"
+#include "rtc_base/trace_event.h"
+#include "video_engine/desktop_capture_impl.h"
+#include "modules/desktop_capture/desktop_frame.h"
+#include "modules/desktop_capture/desktop_capture_options.h"
+#include "modules/video_capture/video_capture.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/StaticPrefs_media.h"
+
+#include "PerformanceRecorder.h"
+
+#if defined(_WIN32)
+#  include "platform_uithread.h"
+#else
+#  include "rtc_base/platform_thread.h"
+#endif
+
+namespace webrtc {
+
+ScreenDeviceInfoImpl::ScreenDeviceInfoImpl(const int32_t id) : _id(id) {}
+
+ScreenDeviceInfoImpl::~ScreenDeviceInfoImpl(void) {}
+
+int32_t ScreenDeviceInfoImpl::Init() {
+  desktop_device_info_ =
+      std::unique_ptr<DesktopDeviceInfo>(DesktopDeviceInfoImpl::Create());
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::Refresh() {
+  desktop_device_info_->Refresh();
+  return 0;
+}
+
+uint32_t ScreenDeviceInfoImpl::NumberOfDevices() {
+  return desktop_device_info_->getDisplayDeviceCount();
+}
+
+int32_t ScreenDeviceInfoImpl::GetDeviceName(
+    uint32_t deviceNumber, char* deviceNameUTF8, uint32_t deviceNameUTF8Size,
+    char* deviceUniqueIdUTF8, uint32_t deviceUniqueIdUTF8Size,
+    char* productUniqueIdUTF8, uint32_t productUniqueIdUTF8Size, pid_t* pid) {
+  DesktopDisplayDevice desktopDisplayDevice;
+
+  // always initialize output
+  if (deviceNameUTF8 && deviceNameUTF8Size > 0) {
+    memset(deviceNameUTF8, 0, deviceNameUTF8Size);
+  }
+
+  if (deviceUniqueIdUTF8 && deviceUniqueIdUTF8Size > 0) {
+    memset(deviceUniqueIdUTF8, 0, deviceUniqueIdUTF8Size);
+  }
+  if (productUniqueIdUTF8 && productUniqueIdUTF8Size > 0) {
+    memset(productUniqueIdUTF8, 0, productUniqueIdUTF8Size);
+  }
+
+  if (desktop_device_info_->getDesktopDisplayDeviceInfo(
+          deviceNumber, desktopDisplayDevice) == 0) {
+    size_t len;
+
+    const char* deviceName = desktopDisplayDevice.getDeviceName();
+    len = deviceName ? strlen(deviceName) : 0;
+    if (len && deviceNameUTF8 && len < deviceNameUTF8Size) {
+      memcpy(deviceNameUTF8, deviceName, len);
+    }
+
+    const char* deviceUniqueId = desktopDisplayDevice.getUniqueIdName();
+    len = deviceUniqueId ? strlen(deviceUniqueId) : 0;
+    if (len && deviceUniqueIdUTF8 && len < deviceUniqueIdUTF8Size) {
+      memcpy(deviceUniqueIdUTF8, deviceUniqueId, len);
+    }
+  }
+
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::DisplayCaptureSettingsDialogBox(
+    const char* deviceUniqueIdUTF8, const char* dialogTitleUTF8,
+    void* parentWindow, uint32_t positionX, uint32_t positionY) {
+  // no device properties to change
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::NumberOfCapabilities(
+    const char* deviceUniqueIdUTF8) {
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::GetCapability(
+    const char* deviceUniqueIdUTF8, const uint32_t deviceCapabilityNumber,
+    VideoCaptureCapability& capability) {
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::GetBestMatchedCapability(
+    const char* deviceUniqueIdUTF8, const VideoCaptureCapability& requested,
+    VideoCaptureCapability& resulting) {
+  return 0;
+}
+
+int32_t ScreenDeviceInfoImpl::GetOrientation(const char* deviceUniqueIdUTF8,
+                                             VideoRotation& orientation) {
+  return 0;
+}
+
+VideoCaptureModule* DesktopCaptureImpl::Create(const int32_t id,
+                                               const char* uniqueId,
+                                               const CaptureDeviceType type) {
+  return new rtc::RefCountedObject<DesktopCaptureImpl>(id, uniqueId, type);
+}
+
+int32_t WindowDeviceInfoImpl::Init() {
+  desktop_device_info_ =
+      std::unique_ptr<DesktopDeviceInfo>(DesktopDeviceInfoImpl::Create());
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::Refresh() {
+  desktop_device_info_->Refresh();
+  return 0;
+}
+
+uint32_t WindowDeviceInfoImpl::NumberOfDevices() {
+  return desktop_device_info_->getWindowCount();
+}
+
+int32_t WindowDeviceInfoImpl::GetDeviceName(
+    uint32_t deviceNumber, char* deviceNameUTF8, uint32_t deviceNameUTF8Size,
+    char* deviceUniqueIdUTF8, uint32_t deviceUniqueIdUTF8Size,
+    char* productUniqueIdUTF8, uint32_t productUniqueIdUTF8Size, pid_t* pid) {
+  DesktopDisplayDevice desktopDisplayDevice;
+
+  // always initialize output
+  if (deviceNameUTF8 && deviceNameUTF8Size > 0) {
+    memset(deviceNameUTF8, 0, deviceNameUTF8Size);
+  }
+  if (deviceUniqueIdUTF8 && deviceUniqueIdUTF8Size > 0) {
+    memset(deviceUniqueIdUTF8, 0, deviceUniqueIdUTF8Size);
+  }
+  if (productUniqueIdUTF8 && productUniqueIdUTF8Size > 0) {
+    memset(productUniqueIdUTF8, 0, productUniqueIdUTF8Size);
+  }
+
+  if (desktop_device_info_->getWindowInfo(deviceNumber, desktopDisplayDevice) ==
+      0) {
+    size_t len;
+
+    const char* deviceName = desktopDisplayDevice.getDeviceName();
+    len = deviceName ? strlen(deviceName) : 0;
+    if (len && deviceNameUTF8 && len < deviceNameUTF8Size) {
+      memcpy(deviceNameUTF8, deviceName, len);
+    }
+
+    const char* deviceUniqueId = desktopDisplayDevice.getUniqueIdName();
+    len = deviceUniqueId ? strlen(deviceUniqueId) : 0;
+    if (len && deviceUniqueIdUTF8 && len < deviceUniqueIdUTF8Size) {
+      memcpy(deviceUniqueIdUTF8, deviceUniqueId, len);
+    }
+    if (pid) {
+      *pid = desktopDisplayDevice.getPid();
+    }
+  }
+
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::DisplayCaptureSettingsDialogBox(
+    const char* deviceUniqueIdUTF8, const char* dialogTitleUTF8,
+    void* parentWindow, uint32_t positionX, uint32_t positionY) {
+  // no device properties to change
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::NumberOfCapabilities(
+    const char* deviceUniqueIdUTF8) {
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::GetCapability(
+    const char* deviceUniqueIdUTF8, const uint32_t deviceCapabilityNumber,
+    VideoCaptureCapability& capability) {
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::GetBestMatchedCapability(
+    const char* deviceUniqueIdUTF8, const VideoCaptureCapability& requested,
+    VideoCaptureCapability& resulting) {
+  return 0;
+}
+
+int32_t WindowDeviceInfoImpl::GetOrientation(const char* deviceUniqueIdUTF8,
+                                             VideoRotation& orientation) {
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::Init() {
+  desktop_device_info_ =
+      std::unique_ptr<DesktopDeviceInfo>(DesktopDeviceInfoImpl::Create());
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::Refresh() {
+  desktop_device_info_->Refresh();
+  return 0;
+}
+
+uint32_t BrowserDeviceInfoImpl::NumberOfDevices() {
+  return desktop_device_info_->getTabCount();
+}
+
+int32_t BrowserDeviceInfoImpl::GetDeviceName(
+    uint32_t deviceNumber, char* deviceNameUTF8, uint32_t deviceNameUTF8Size,
+    char* deviceUniqueIdUTF8, uint32_t deviceUniqueIdUTF8Size,
+    char* productUniqueIdUTF8, uint32_t productUniqueIdUTF8Size, pid_t* pid) {
+  DesktopTab desktopTab;
+
+  // always initialize output
+  if (deviceNameUTF8 && deviceNameUTF8Size > 0) {
+    memset(deviceNameUTF8, 0, deviceNameUTF8Size);
+  }
+  if (deviceUniqueIdUTF8 && deviceUniqueIdUTF8Size > 0) {
+    memset(deviceUniqueIdUTF8, 0, deviceUniqueIdUTF8Size);
+  }
+  if (productUniqueIdUTF8 && productUniqueIdUTF8Size > 0) {
+    memset(productUniqueIdUTF8, 0, productUniqueIdUTF8Size);
+  }
+
+  if (desktop_device_info_->getTabInfo(deviceNumber, desktopTab) == 0) {
+    size_t len;
+
+    const char* deviceName = desktopTab.getTabName();
+    len = deviceName ? strlen(deviceName) : 0;
+    if (len && deviceNameUTF8 && len < deviceNameUTF8Size) {
+      memcpy(deviceNameUTF8, deviceName, len);
+    }
+
+    const char* deviceUniqueId = desktopTab.getUniqueIdName();
+    len = deviceUniqueId ? strlen(deviceUniqueId) : 0;
+    if (len && deviceUniqueIdUTF8 && len < deviceUniqueIdUTF8Size) {
+      memcpy(deviceUniqueIdUTF8, deviceUniqueId, len);
+    }
+  }
+
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::DisplayCaptureSettingsDialogBox(
+    const char* deviceUniqueIdUTF8, const char* dialogTitleUTF8,
+    void* parentWindow, uint32_t positionX, uint32_t positionY) {
+  // no device properties to change
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::NumberOfCapabilities(
+    const char* deviceUniqueIdUTF8) {
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::GetCapability(
+    const char* deviceUniqueIdUTF8, const uint32_t deviceCapabilityNumber,
+    VideoCaptureCapability& capability) {
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::GetBestMatchedCapability(
+    const char* deviceUniqueIdUTF8, const VideoCaptureCapability& requested,
+    VideoCaptureCapability& resulting) {
+  return 0;
+}
+
+int32_t BrowserDeviceInfoImpl::GetOrientation(const char* deviceUniqueIdUTF8,
+                                              VideoRotation& orientation) {
+  return 0;
+}
+
+VideoCaptureModule::DeviceInfo* DesktopCaptureImpl::CreateDeviceInfo(
+    const int32_t id, const CaptureDeviceType type) {
+  if (type == CaptureDeviceType::Screen) {
+    ScreenDeviceInfoImpl* pScreenDeviceInfoImpl = new ScreenDeviceInfoImpl(id);
+    if (!pScreenDeviceInfoImpl || pScreenDeviceInfoImpl->Init()) {
+      delete pScreenDeviceInfoImpl;
+      pScreenDeviceInfoImpl = NULL;
+    }
+    return pScreenDeviceInfoImpl;
+  } else if (type == CaptureDeviceType::Window) {
+    WindowDeviceInfoImpl* pWindowDeviceInfoImpl = new WindowDeviceInfoImpl(id);
+    if (!pWindowDeviceInfoImpl || pWindowDeviceInfoImpl->Init()) {
+      delete pWindowDeviceInfoImpl;
+      pWindowDeviceInfoImpl = NULL;
+    }
+    return pWindowDeviceInfoImpl;
+  } else if (type == CaptureDeviceType::Browser) {
+    BrowserDeviceInfoImpl* pBrowserDeviceInfoImpl =
+        new BrowserDeviceInfoImpl(id);
+    if (!pBrowserDeviceInfoImpl || pBrowserDeviceInfoImpl->Init()) {
+      delete pBrowserDeviceInfoImpl;
+      pBrowserDeviceInfoImpl = NULL;
+    }
+    return pBrowserDeviceInfoImpl;
+  }
+  return NULL;
+}
+
+const char* DesktopCaptureImpl::CurrentDeviceName() const {
+  return _deviceUniqueId.c_str();
+}
+
+static DesktopCaptureOptions CreateDesktopCaptureOptions() {
+  DesktopCaptureOptions options = DesktopCaptureOptions::CreateDefault();
+  // Leave desktop effects enabled during WebRTC captures.
+  options.set_disable_effects(false);
+
+#if defined(WEBRTC_WIN)
+  if (mozilla::StaticPrefs::media_webrtc_capture_allow_directx()) {
+    options.set_allow_directx_capturer(true);
+    options.set_allow_use_magnification_api(false);
+  } else {
+    options.set_allow_use_magnification_api(true);
+  }
+  options.set_allow_cropping_window_capturer(true);
+#  if defined(RTC_ENABLE_WIN_WGC)
+  if (mozilla::StaticPrefs::media_webrtc_capture_allow_wgc()) {
+    options.set_allow_wgc_capturer(true);
+  }
+#  endif
+#endif
+
+#if defined(WEBRTC_MAC)
+  if (mozilla::StaticPrefs::media_webrtc_capture_allow_iosurface()) {
+    options.set_allow_iosurface(true);
+  }
+#endif
+
+#if defined(WEBRTC_USE_PIPEWIRE)
+  if (mozilla::StaticPrefs::media_webrtc_capture_allow_pipewire()) {
+    options.set_allow_pipewire(true);
+  }
+#endif
+
+  return options;
+}
+
+int32_t DesktopCaptureImpl::LazyInitDesktopCapturer() {
+  // Already initialized
+  if (desktop_capturer_cursor_composer_) {
+    return 0;
+  }
+
+  DesktopCaptureOptions options = CreateDesktopCaptureOptions();
+
+  if (_deviceType == CaptureDeviceType::Screen) {
+    std::unique_ptr<DesktopCapturer> pScreenCapturer =
+        DesktopCapturer::CreateScreenCapturer(options);
+    if (!pScreenCapturer.get()) {
+      return -1;
+    }
+
+    DesktopCapturer::SourceId sourceId = atoi(_deviceUniqueId.c_str());
+    pScreenCapturer->SelectSource(sourceId);
+
+    desktop_capturer_cursor_composer_ =
+        std::unique_ptr<DesktopAndCursorComposer>(
+            new DesktopAndCursorComposer(std::move(pScreenCapturer), options));
+  } else if (_deviceType == CaptureDeviceType::Window) {
+#if defined(RTC_ENABLE_WIN_WGC)
+    options.set_allow_wgc_capturer_fallback(true);
+#endif
+    std::unique_ptr<DesktopCapturer> pWindowCapturer =
+        DesktopCapturer::CreateWindowCapturer(options);
+    if (!pWindowCapturer.get()) {
+      return -1;
+    }
+
+    DesktopCapturer::SourceId sourceId = atoi(_deviceUniqueId.c_str());
+    pWindowCapturer->SelectSource(sourceId);
+
+    desktop_capturer_cursor_composer_ =
+        std::unique_ptr<DesktopAndCursorComposer>(
+            new DesktopAndCursorComposer(std::move(pWindowCapturer), options));
+  } else if (_deviceType == CaptureDeviceType::Browser) {
+    // XXX We don't capture cursors, so avoid the extra indirection layer. We
+    // could also pass null for the pMouseCursorMonitor.
+    desktop_capturer_cursor_composer_ =
+        DesktopCapturer::CreateTabCapturer(options);
+    if (!desktop_capturer_cursor_composer_) {
+      return -1;
+    }
+
+    DesktopCapturer::SourceId sourceId = atoi(_deviceUniqueId.c_str());
+    desktop_capturer_cursor_composer_->SelectSource(sourceId);
+  }
+  return 0;
+}
+
+DesktopCaptureImpl::DesktopCaptureImpl(const int32_t id, const char* uniqueId,
+                                       const CaptureDeviceType type)
+    : _id(id),
+      _tracking_id(
+          mozilla::TrackingId(CaptureEngineToTrackingSourceStr([&] {
+                                switch (type) {
+                                  case CaptureDeviceType::Screen:
+                                    return CaptureEngine::ScreenEngine;
+                                  case CaptureDeviceType::Window:
+                                    return CaptureEngine::WinEngine;
+                                  case CaptureDeviceType::Browser:
+                                    return CaptureEngine::BrowserEngine;
+                                  default:
+                                    return CaptureEngine::InvalidEngine;
+                                }
+                              }()),
+                              id)),
+      _deviceUniqueId(uniqueId),
+      _deviceType(type),
+      _requestedCapability(),
+      _rotateFrame(kVideoRotation_0),
+      last_capture_time_ms_(rtc::TimeMillis()),
+      time_event_(EventWrapper::Create()),
+      capturer_thread_(nullptr),
+      started_(false) {
+  _requestedCapability.width = kDefaultWidth;
+  _requestedCapability.height = kDefaultHeight;
+  _requestedCapability.maxFPS = 30;
+  _requestedCapability.videoType = VideoType::kI420;
+  _maxFPSNeeded = 1000 / _requestedCapability.maxFPS;
+  memset(_incomingFrameTimesNanos, 0, sizeof(_incomingFrameTimesNanos));
+}
+
+DesktopCaptureImpl::~DesktopCaptureImpl() {
+  time_event_->Set();
+  if (capturer_thread_) {
+#if defined(_WIN32)
+    capturer_thread_->Stop();
+#else
+    capturer_thread_->Finalize();
+#endif
+  }
+}
+
+void DesktopCaptureImpl::RegisterCaptureDataCallback(
+    rtc::VideoSinkInterface<VideoFrame>* dataCallback) {
+  rtc::CritScope lock(&_apiCs);
+  _dataCallBacks.insert(dataCallback);
+}
+
+void DesktopCaptureImpl::DeRegisterCaptureDataCallback(
+    rtc::VideoSinkInterface<VideoFrame>* dataCallback) {
+  rtc::CritScope lock(&_apiCs);
+  auto it = _dataCallBacks.find(dataCallback);
+  if (it != _dataCallBacks.end()) {
+    _dataCallBacks.erase(it);
+  }
+}
+
+int32_t DesktopCaptureImpl::StopCaptureIfAllClientsClose() {
+  if (_dataCallBacks.empty()) {
+    return StopCapture();
+  } else {
+    return 0;
+  }
+}
+
+int32_t DesktopCaptureImpl::DeliverCapturedFrame(
+    webrtc::VideoFrame& captureFrame) {
+  UpdateFrameCount();  // frame count used for local frame rate callBack.
+
+  // Set the capture time
+  captureFrame.set_timestamp_us(rtc::TimeMicros());
+
+  if (captureFrame.render_time_ms() == last_capture_time_ms_) {
+    // We don't allow the same capture time for two frames, drop this one.
+    return -1;
+  }
+  last_capture_time_ms_ = captureFrame.render_time_ms();
+
+  for (auto dataCallBack : _dataCallBacks) {
+    dataCallBack->OnFrame(captureFrame);
+  }
+
+  return 0;
+}
+
+// Originally copied from VideoCaptureImpl::IncomingFrame, but has diverged
+// somewhat. See Bug 1038324 and bug 1738946.
+int32_t DesktopCaptureImpl::IncomingFrame(
+    uint8_t* videoFrame, size_t videoFrameLength, size_t widthWithPadding,
+    const VideoCaptureCapability& frameInfo) {
+  int64_t startProcessTime = rtc::TimeNanos();
+  rtc::CritScope cs(&_apiCs);
+
+  const int32_t width = frameInfo.width;
+  const int32_t height = frameInfo.height;
+
+  // Not encoded, convert to I420.
+  if (frameInfo.videoType != VideoType::kMJPEG &&
+      CalcBufferSize(frameInfo.videoType, width, abs(height)) !=
+          videoFrameLength) {
+    RTC_LOG(LS_ERROR) << "Wrong incoming frame length.";
+    return -1;
+  }
+
+  int stride_y = width;
+  int stride_uv = (width + 1) / 2;
+
+  // Setting absolute height (in case it was negative).
+  // In Windows, the image starts bottom left, instead of top left.
+  // Setting a negative source height, inverts the image (within LibYuv).
+
+  mozilla::PerformanceRecorder<mozilla::CopyVideoStage> rec(
+      "DesktopCaptureImpl::ConvertToI420"_ns, _tracking_id, width, abs(height));
+  // TODO(nisse): Use a pool?
+  rtc::scoped_refptr<I420Buffer> buffer =
+      I420Buffer::Create(width, abs(height), stride_y, stride_uv, stride_uv);
+
+  const int conversionResult = libyuv::ConvertToI420(
+      videoFrame, videoFrameLength, buffer.get()->MutableDataY(),
+      buffer.get()->StrideY(), buffer.get()->MutableDataU(),
+      buffer.get()->StrideU(), buffer.get()->MutableDataV(),
+      buffer.get()->StrideV(), 0, 0,  // No Cropping
+      static_cast<int>(widthWithPadding), height, width, height,
+      libyuv::kRotate0, ConvertVideoType(frameInfo.videoType));
+  if (conversionResult != 0) {
+    RTC_LOG(LS_ERROR) << "Failed to convert capture frame from type "
+                      << static_cast<int>(frameInfo.videoType) << "to I420.";
+    return -1;
+  }
+  rec.Record();
+
+  VideoFrame captureFrame(buffer, 0, rtc::TimeMillis(), kVideoRotation_0);
+
+  DeliverCapturedFrame(captureFrame);
+
+  const int64_t processTime =
+      (rtc::TimeNanos() - startProcessTime) / rtc::kNumNanosecsPerMillisec;
+
+  if (processTime > 10) {
+    RTC_LOG(LS_WARNING) << "Too long processing time of incoming frame: "
+                        << processTime << " ms";
+  }
+
+  return 0;
+}
+
+int32_t DesktopCaptureImpl::SetCaptureRotation(VideoRotation rotation) {
+  rtc::CritScope lock(&_apiCs);
+  _rotateFrame = rotation;
+  return 0;
+}
+
+bool DesktopCaptureImpl::SetApplyRotation(bool enable) { return true; }
+
+void DesktopCaptureImpl::UpdateFrameCount() {
+  if (_incomingFrameTimesNanos[0] == 0) {
+    // first no shift
+  } else {
+    // shift
+    for (int i = (kFrameRateCountHistorySize - 2); i >= 0; i--) {
+      _incomingFrameTimesNanos[i + 1] = _incomingFrameTimesNanos[i];
+    }
+  }
+  _incomingFrameTimesNanos[0] = rtc::TimeNanos();
+}
+
+uint32_t DesktopCaptureImpl::CalculateFrameRate(int64_t now_ns) {
+  int32_t num = 0;
+  int32_t nrOfFrames = 0;
+  for (num = 1; num < (kFrameRateCountHistorySize - 1); num++) {
+    if (_incomingFrameTimesNanos[num] <= 0 ||
+        (now_ns - _incomingFrameTimesNanos[num]) /
+                rtc::kNumNanosecsPerMillisec >
+            kFrameRateHistoryWindowMs)  // don't use data older than 2sec
+    {
+      break;
+    } else {
+      nrOfFrames++;
+    }
+  }
+  if (num > 1) {
+    int64_t diff = (now_ns - _incomingFrameTimesNanos[num - 1]) /
+                   rtc::kNumNanosecsPerMillisec;
+    if (diff > 0) {
+      return uint32_t((nrOfFrames * 1000.0f / diff) + 0.5f);
+    }
+  }
+
+  return nrOfFrames;
+}
+
+void DesktopCaptureImpl::LazyInitCaptureThread() {
+  MOZ_ASSERT(desktop_capturer_cursor_composer_,
+             "DesktopCapturer must be initialized before the capture thread");
+  if (capturer_thread_) {
+    return;
+  }
+#if defined(_WIN32)
+  capturer_thread_ = std::make_unique<rtc::PlatformUIThread>(
+      std::function([self = (void*)this]() { Run(self); }),
+      "ScreenCaptureThread", rtc::ThreadAttributes{});
+  capturer_thread_->RequestCallbackTimer(_maxFPSNeeded);
+#else
+  auto self = rtc::scoped_refptr<DesktopCaptureImpl>(this);
+  capturer_thread_ =
+      std::make_unique<rtc::PlatformThread>(rtc::PlatformThread::SpawnJoinable(
+          [self] { self->process(); }, "ScreenCaptureThread"));
+#endif
+  started_ = true;
+}
+
+int32_t DesktopCaptureImpl::StartCapture(
+    const VideoCaptureCapability& capability) {
+  rtc::CritScope lock(&_apiCs);
+  // See Bug 1780884 for followup on understanding why multiple calls happen.
+  // MOZ_ASSERT(!started_, "Capture must be stopped before Start() can be
+  // called");
+  if (started_) {
+    return 0;
+  }
+
+  if (uint32_t err = LazyInitDesktopCapturer(); err) {
+    return err;
+  }
+  started_ = true;
+  _requestedCapability = capability;
+  _maxFPSNeeded = _requestedCapability.maxFPS > 0
+                      ? 1000 / _requestedCapability.maxFPS
+                      : 1000;
+  LazyInitCaptureThread();
+
+  return 0;
+}
+
+bool DesktopCaptureImpl::FocusOnSelectedSource() {
+  if (uint32_t err = LazyInitDesktopCapturer(); err) {
+    return false;
+  }
+
+  return desktop_capturer_cursor_composer_->FocusOnSelectedSource();
+}
+
+int32_t DesktopCaptureImpl::StopCapture() {
+  if (started_) {
+    started_ = false;
+    MOZ_ASSERT(capturer_thread_, "Capturer thread should be initialized.");
+
+#if defined(_WIN32)
+    capturer_thread_
+        ->Stop();  // thread is guaranteed stopped before this returns
+#else
+    capturer_thread_
+        ->Finalize();  // thread is guaranteed stopped before this returns
+#endif
+    desktop_capturer_cursor_composer_.reset();
+    cursor_composer_started_ = false;
+    capturer_thread_.reset();
+    return 0;
+  }
+  return -1;
+}
+
+bool DesktopCaptureImpl::CaptureStarted() { return started_; }
+
+int32_t DesktopCaptureImpl::CaptureSettings(VideoCaptureCapability& settings) {
+  return -1;
+}
+
+void DesktopCaptureImpl::OnCaptureResult(DesktopCapturer::Result result,
+                                         std::unique_ptr<DesktopFrame> frame) {
+  if (frame.get() == nullptr) return;
+  uint8_t* videoFrame = frame->data();
+  VideoCaptureCapability frameInfo;
+  frameInfo.width = frame->size().width();
+  frameInfo.height = frame->size().height();
+  frameInfo.videoType = VideoType::kARGB;
+
+  size_t videoFrameLength =
+      frameInfo.width * frameInfo.height * DesktopFrame::kBytesPerPixel;
+  IncomingFrame(videoFrame, videoFrameLength,
+                frame->stride() / DesktopFrame::kBytesPerPixel, frameInfo);
+}
+
+void DesktopCaptureImpl::process() {
+  // We need to call Start on the same thread we call CaptureFrame on.
+  if (!cursor_composer_started_) {
+    desktop_capturer_cursor_composer_->Start(this);
+    cursor_composer_started_ = true;
+  }
+#if defined(WEBRTC_WIN)
+  ProcessIter();
+#else
+  do {
+    ProcessIter();
+  } while (started_);
+#endif
+}
+
+void DesktopCaptureImpl::ProcessIter() {
+// We should deliver at least one frame before stopping
+#if !defined(_WIN32)
+  int64_t startProcessTime = rtc::TimeNanos();
+#endif
+
+  // Don't leak while we're looping
+  base::ScopedNSAutoreleasePool autoreleasepool;
+
+#if defined(WEBRTC_MAC)
+  // Give cycles to the RunLoop so frame callbacks can happen
+  CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.01, true);
+#endif
+
+  desktop_capturer_cursor_composer_->CaptureFrame();
+
+#if !defined(_WIN32)
+  const uint32_t processTime =
+      ((uint32_t)(rtc::TimeNanos() - startProcessTime)) /
+      rtc::kNumNanosecsPerMillisec;
+  // Use at most x% CPU or limit framerate
+  const float sleepTimeFactor = (100.0f / kMaxDesktopCaptureCpuUsage) - 1.0f;
+  const uint32_t sleepTime = sleepTimeFactor * processTime;
+  time_event_->Wait(std::max<uint32_t>(_maxFPSNeeded, sleepTime));
+#endif
+
+#if defined(WEBRTC_WIN)
+// Let the timer events in PlatformUIThread drive process,
+// don't sleep.
+#elif defined(WEBRTC_MAC)
+  sched_yield();
+#else
+  static const struct timespec ts_null = {0};
+  nanosleep(&ts_null, nullptr);
+#endif
+}
+
+}  // namespace webrtc