content/browser/renderer_host/media/desktop_capture_device.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/renderer_host/media/desktop_capture_device.h"
   6
   7 #include "base/bind.h"
   8 #include "base/location.h"
   9 #include "base/logging.h"
  10 #include "base/sequenced_task_runner.h"
  11 #include "base/strings/string_number_conversions.h"
  12 #include "base/synchronization/lock.h"
  13 #include "base/threading/sequenced_worker_pool.h"
  14 #include "content/public/browser/browser_thread.h"
  15 #include "content/public/browser/desktop_media_id.h"
  16 #include "media/base/video_util.h"
  17 #include "third_party/libyuv/include/libyuv/scale_argb.h"
  18 #include "third_party/webrtc/modules/desktop_capture/desktop_and_cursor_composer.h"
  19 #include "third_party/webrtc/modules/desktop_capture/desktop_capture_options.h"
  20 #include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"
  21 #include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
  22 #include "third_party/webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
  23 #include "third_party/webrtc/modules/desktop_capture/screen_capturer.h"
  24 #include "third_party/webrtc/modules/desktop_capture/window_capturer.h"
  25
  26 namespace content {
  27
  28 namespace {
  29
  30 // Maximum CPU time percentage of a single core that can be consumed for desktop
  31 // capturing. This means that on systems where screen scraping is slow we may
  32 // need to capture at frame rate lower than requested. This is necessary to keep
  33 // UI responsive.
  34 const int kMaximumCpuConsumptionPercentage = 50;
  35
  36 webrtc::DesktopRect ComputeLetterboxRect(
  37     const webrtc::DesktopSize& max_size,
  38     const webrtc::DesktopSize& source_size) {
  39   gfx::Rect result = media::ComputeLetterboxRegion(
  40       gfx::Rect(0, 0, max_size.width(), max_size.height()),
  41       gfx::Size(source_size.width(), source_size.height()));
  42   return webrtc::DesktopRect::MakeLTRB(
  43       result.x(), result.y(), result.right(), result.bottom());
  44 }
  45
  46 }  // namespace
  47
  48 class DesktopCaptureDevice::Core
  49     : public base::RefCountedThreadSafe<Core>,
  50       public webrtc::DesktopCapturer::Callback {
  51  public:
  52   Core(scoped_refptr<base::SequencedTaskRunner> task_runner,
  53        scoped_ptr<webrtc::DesktopCapturer> capturer);
  54
  55   // Implementation of VideoCaptureDevice methods.
  56   void AllocateAndStart(const media::VideoCaptureParams& params,
  57                         scoped_ptr<Client> client);
  58   void StopAndDeAllocate();
  59
  60  private:
  61   friend class base::RefCountedThreadSafe<Core>;
  62   virtual ~Core();
  63
  64   // webrtc::DesktopCapturer::Callback interface
  65   virtual webrtc::SharedMemory* CreateSharedMemory(size_t size) OVERRIDE;
  66   virtual void OnCaptureCompleted(webrtc::DesktopFrame* frame) OVERRIDE;
  67
  68   // Helper methods that run on the |task_runner_|. Posted from the
  69   // corresponding public methods.
  70   void DoAllocateAndStart(const media::VideoCaptureParams& params,
  71                           scoped_ptr<Client> client);
  72   void DoStopAndDeAllocate();
  73
  74   // Chooses new output properties based on the supplied source size and the
  75   // properties requested to Allocate(), and dispatches OnFrameInfo[Changed]
  76   // notifications.
  77   void RefreshCaptureFormat(const webrtc::DesktopSize& frame_size);
  78
  79   // Method that is scheduled on |task_runner_| to be called on regular interval
  80   // to capture a frame.
  81   void OnCaptureTimer();
  82
  83   // Captures a frame and schedules timer for the next one.
  84   void CaptureFrameAndScheduleNext();
  85
  86   // Captures a single frame.
  87   void DoCapture();
  88
  89   // Task runner used for capturing operations.
  90   scoped_refptr<base::SequencedTaskRunner> task_runner_;
  91
  92   // The underlying DesktopCapturer instance used to capture frames.
  93   scoped_ptr<webrtc::DesktopCapturer> desktop_capturer_;
  94
  95   // The device client which proxies device events to the controller. Accessed
  96   // on the task_runner_ thread.
  97   scoped_ptr<Client> client_;
  98
  99   // Requested video capture format (width, height, frame rate, etc).
 100   media::VideoCaptureParams requested_params_;
 101
 102   // Actual video capture format being generated.
 103   media::VideoCaptureFormat capture_format_;
 104
 105   // Size of frame most recently captured from the source.
 106   webrtc::DesktopSize previous_frame_size_;
 107
 108   // DesktopFrame into which captured frames are down-scaled and/or letterboxed,
 109   // depending upon the caller's requested capture capabilities. If frames can
 110   // be returned to the caller directly then this is NULL.
 111   scoped_ptr<webrtc::DesktopFrame> output_frame_;
 112
 113   // Sub-rectangle of |output_frame_| into which the source will be scaled
 114   // and/or letterboxed.
 115   webrtc::DesktopRect output_rect_;
 116
 117   // True when we have delayed OnCaptureTimer() task posted on
 118   // |task_runner_|.
 119   bool capture_task_posted_;
 120
 121   // True when waiting for |desktop_capturer_| to capture current frame.
 122   bool capture_in_progress_;
 123
 124   DISALLOW_COPY_AND_ASSIGN(Core);
 125 };
 126
 127 DesktopCaptureDevice::Core::Core(
 128     scoped_refptr<base::SequencedTaskRunner> task_runner,
 129     scoped_ptr<webrtc::DesktopCapturer> capturer)
 130     : task_runner_(task_runner),
 131       desktop_capturer_(capturer.Pass()),
 132       capture_task_posted_(false),
 133       capture_in_progress_(false) {}
 134
 135 DesktopCaptureDevice::Core::~Core() {
 136 }
 137
 138 void DesktopCaptureDevice::Core::AllocateAndStart(
 139     const media::VideoCaptureParams& params,
 140     scoped_ptr<Client> client) {
 141   DCHECK_GT(params.requested_format.frame_size.GetArea(), 0);
 142   DCHECK_GT(params.requested_format.frame_rate, 0);
 143
 144   task_runner_->PostTask(
 145       FROM_HERE,
 146       base::Bind(
 147           &Core::DoAllocateAndStart, this, params, base::Passed(&client)));
 148 }
 149
 150 void DesktopCaptureDevice::Core::StopAndDeAllocate() {
 151   task_runner_->PostTask(FROM_HERE,
 152                          base::Bind(&Core::DoStopAndDeAllocate, this));
 153 }
 154
 155 webrtc::SharedMemory*
 156 DesktopCaptureDevice::Core::CreateSharedMemory(size_t size) {
 157   return NULL;
 158 }
 159
 160 void DesktopCaptureDevice::Core::OnCaptureCompleted(
 161     webrtc::DesktopFrame* frame) {
 162   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 163   DCHECK(capture_in_progress_);
 164
 165   capture_in_progress_ = false;
 166
 167   if (!frame) {
 168     LOG(ERROR) << "Failed to capture a frame.";
 169     client_->OnError();
 170     return;
 171   }
 172
 173   if (!client_)
 174     return;
 175
 176   scoped_ptr<webrtc::DesktopFrame> owned_frame(frame);
 177
 178   // Handle initial frame size and size changes.
 179   RefreshCaptureFormat(frame->size());
 180
 181   webrtc::DesktopSize output_size(capture_format_.frame_size.width(),
 182                                   capture_format_.frame_size.height());
 183   size_t output_bytes = output_size.width() * output_size.height() *
 184       webrtc::DesktopFrame::kBytesPerPixel;
 185   const uint8_t* output_data = NULL;
 186   scoped_ptr<uint8_t[]> flipped_frame_buffer;
 187
 188   if (frame->size().equals(output_size)) {
 189     // If the captured frame matches the output size, we can return the pixel
 190     // data directly, without scaling.
 191     output_data = frame->data();
 192
 193     // If the |frame| generated by the screen capturer is inverted then we need
 194     // to flip |frame|.
 195     // This happens only on a specific platform. Refer to crbug.com/306876.
 196     if (frame->stride() < 0) {
 197       int height = frame->size().height();
 198       int bytes_per_row =
 199           frame->size().width() * webrtc::DesktopFrame::kBytesPerPixel;
 200       flipped_frame_buffer.reset(new uint8_t[output_bytes]);
 201       uint8_t* dest = flipped_frame_buffer.get();
 202       for (int row = 0; row < height; ++row) {
 203         memcpy(dest, output_data, bytes_per_row);
 204         dest += bytes_per_row;
 205         output_data += frame->stride();
 206       }
 207       output_data = flipped_frame_buffer.get();
 208     }
 209   } else {
 210     // Otherwise we need to down-scale and/or letterbox to the target format.
 211
 212     // Allocate a buffer of the correct size to scale the frame into.
 213     // |output_frame_| is cleared whenever |output_rect_| changes, so we don't
 214     // need to worry about clearing out stale pixel data in letterboxed areas.
 215     if (!output_frame_) {
 216       output_frame_.reset(new webrtc::BasicDesktopFrame(output_size));
 217       memset(output_frame_->data(), 0, output_bytes);
 218     }
 219     DCHECK(output_frame_->size().equals(output_size));
 220
 221     // TODO(wez): Optimize this to scale only changed portions of the output,
 222     // using ARGBScaleClip().
 223     uint8_t* output_rect_data = output_frame_->data() +
 224         output_frame_->stride() * output_rect_.top() +
 225         webrtc::DesktopFrame::kBytesPerPixel * output_rect_.left();
 226     libyuv::ARGBScale(frame->data(), frame->stride(),
 227                       frame->size().width(), frame->size().height(),
 228                       output_rect_data, output_frame_->stride(),
 229                       output_rect_.width(), output_rect_.height(),
 230                       libyuv::kFilterBilinear);
 231     output_data = output_frame_->data();
 232   }
 233
 234   client_->OnIncomingCapturedFrame(
 235       output_data, output_bytes, base::TimeTicks::Now(), 0, capture_format_);
 236 }
 237
 238 void DesktopCaptureDevice::Core::DoAllocateAndStart(
 239     const media::VideoCaptureParams& params,
 240     scoped_ptr<Client> client) {
 241   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 242   DCHECK(desktop_capturer_);
 243   DCHECK(client.get());
 244   DCHECK(!client_.get());
 245
 246   client_ = client.Pass();
 247   requested_params_ = params;
 248
 249   capture_format_ = requested_params_.requested_format;
 250
 251   // This capturer always outputs ARGB, non-interlaced.
 252   capture_format_.pixel_format = media::PIXEL_FORMAT_ARGB;
 253
 254   desktop_capturer_->Start(this);
 255
 256   CaptureFrameAndScheduleNext();
 257 }
 258
 259 void DesktopCaptureDevice::Core::DoStopAndDeAllocate() {
 260   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 261   client_.reset();
 262   output_frame_.reset();
 263   previous_frame_size_.set(0, 0);
 264   desktop_capturer_.reset();
 265 }
 266
 267 void DesktopCaptureDevice::Core::RefreshCaptureFormat(
 268     const webrtc::DesktopSize& frame_size) {
 269   if (previous_frame_size_.equals(frame_size))
 270     return;
 271
 272   // Clear the output frame, if any, since it will either need resizing, or
 273   // clearing of stale data in letterbox areas, anyway.
 274   output_frame_.reset();
 275
 276   if (previous_frame_size_.is_empty() ||
 277       requested_params_.allow_resolution_change) {
 278     // If this is the first frame, or the receiver supports variable resolution
 279     // then determine the output size by treating the requested width & height
 280     // as maxima.
 281     if (frame_size.width() >
 282             requested_params_.requested_format.frame_size.width() ||
 283         frame_size.height() >
 284             requested_params_.requested_format.frame_size.height()) {
 285       output_rect_ = ComputeLetterboxRect(
 286           webrtc::DesktopSize(
 287               requested_params_.requested_format.frame_size.width(),
 288               requested_params_.requested_format.frame_size.height()),
 289           frame_size);
 290       output_rect_.Translate(-output_rect_.left(), -output_rect_.top());
 291     } else {
 292       output_rect_ = webrtc::DesktopRect::MakeSize(frame_size);
 293     }
 294     capture_format_.frame_size.SetSize(output_rect_.width(),
 295                                        output_rect_.height());
 296   } else {
 297     // Otherwise the output frame size cannot change, so just scale and
 298     // letterbox.
 299     output_rect_ = ComputeLetterboxRect(
 300         webrtc::DesktopSize(capture_format_.frame_size.width(),
 301                             capture_format_.frame_size.height()),
 302         frame_size);
 303   }
 304
 305   previous_frame_size_ = frame_size;
 306 }
 307
 308 void DesktopCaptureDevice::Core::OnCaptureTimer() {
 309   DCHECK(capture_task_posted_);
 310   capture_task_posted_ = false;
 311
 312   if (!client_)
 313     return;
 314
 315   CaptureFrameAndScheduleNext();
 316 }
 317
 318 void DesktopCaptureDevice::Core::CaptureFrameAndScheduleNext() {
 319   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 320   DCHECK(!capture_task_posted_);
 321
 322   base::TimeTicks started_time = base::TimeTicks::Now();
 323   DoCapture();
 324   base::TimeDelta last_capture_duration = base::TimeTicks::Now() - started_time;
 325
 326   // Limit frame-rate to reduce CPU consumption.
 327   base::TimeDelta capture_period = std::max(
 328     (last_capture_duration * 100) / kMaximumCpuConsumptionPercentage,
 329     base::TimeDelta::FromSeconds(1) / capture_format_.frame_rate);
 330
 331   // Schedule a task for the next frame.
 332   capture_task_posted_ = true;
 333   task_runner_->PostDelayedTask(
 334       FROM_HERE, base::Bind(&Core::OnCaptureTimer, this),
 335       capture_period - last_capture_duration);
 336 }
 337
 338 void DesktopCaptureDevice::Core::DoCapture() {
 339   DCHECK(task_runner_->RunsTasksOnCurrentThread());
 340   DCHECK(!capture_in_progress_);
 341
 342   capture_in_progress_ = true;
 343   desktop_capturer_->Capture(webrtc::DesktopRegion());
 344
 345   // Currently only synchronous implementations of DesktopCapturer are
 346   // supported.
 347   DCHECK(!capture_in_progress_);
 348 }
 349
 350 // static
 351 scoped_ptr<media::VideoCaptureDevice> DesktopCaptureDevice::Create(
 352     const DesktopMediaID& source) {
 353   scoped_refptr<base::SequencedWorkerPool> blocking_pool =
 354       BrowserThread::GetBlockingPool();
 355   scoped_refptr<base::SequencedTaskRunner> task_runner =
 356       blocking_pool->GetSequencedTaskRunner(
 357           blocking_pool->GetSequenceToken());
 358
 359   webrtc::DesktopCaptureOptions options =
 360       webrtc::DesktopCaptureOptions::CreateDefault();
 361   // Leave desktop effects enabled during WebRTC captures.
 362   options.set_disable_effects(false);
 363
 364   scoped_ptr<webrtc::DesktopCapturer> capturer;
 365
 366   switch (source.type) {
 367     case DesktopMediaID::TYPE_SCREEN: {
 368       scoped_ptr<webrtc::DesktopCapturer> screen_capturer;
 369       screen_capturer.reset(webrtc::ScreenCapturer::Create(options));
 370       if (screen_capturer) {
 371         capturer.reset(new webrtc::DesktopAndCursorComposer(
 372             screen_capturer.release(),
 373             webrtc::MouseCursorMonitor::CreateForScreen(options)));
 374       }
 375       break;
 376     }
 377
 378     case DesktopMediaID::TYPE_WINDOW: {
 379       scoped_ptr<webrtc::WindowCapturer> window_capturer(
 380           webrtc::WindowCapturer::Create(options));
 381       if (window_capturer && window_capturer->SelectWindow(source.id)) {
 382         capturer.reset(new webrtc::DesktopAndCursorComposer(
 383             window_capturer.release(),
 384             webrtc::MouseCursorMonitor::CreateForWindow(options, source.id)));
 385       }
 386       break;
 387     }
 388
 389     default: {
 390       NOTREACHED();
 391     }
 392   }
 393
 394   scoped_ptr<media::VideoCaptureDevice> result;
 395   if (capturer)
 396     result.reset(new DesktopCaptureDevice(task_runner, capturer.Pass()));
 397
 398   return result.Pass();
 399 }
 400
 401 DesktopCaptureDevice::DesktopCaptureDevice(
 402     scoped_refptr<base::SequencedTaskRunner> task_runner,
 403     scoped_ptr<webrtc::DesktopCapturer> capturer)
 404     : core_(new Core(task_runner, capturer.Pass())) {}
 405
 406 DesktopCaptureDevice::~DesktopCaptureDevice() {
 407   StopAndDeAllocate();
 408 }
 409
 410 void DesktopCaptureDevice::AllocateAndStart(
 411     const media::VideoCaptureParams& params,
 412     scoped_ptr<Client> client) {
 413   core_->AllocateAndStart(params, client.Pass());
 414 }
 415
 416 void DesktopCaptureDevice::StopAndDeAllocate() {
 417   core_->StopAndDeAllocate();
 418 }
 419
 420 }  // namespace content