Interface with webrtc through encoded frames

remoting/protocol/webrtc_video_capturer_adapter.cc

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "remoting/protocol/webrtc_video_capturer_adapter.h"
-
-#include <utility>
-
-#include "remoting/base/constants.h"
-#include "third_party/libyuv/include/libyuv/convert.h"
-#include "third_party/webrtc/media/engine/webrtcvideoframe.h"
-#include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
-
-namespace remoting {
-namespace protocol {
-
-// Number of frames to be captured per second.
-const int kFramesPerSec = 30;
-
-WebrtcVideoCapturerAdapter::WebrtcVideoCapturerAdapter(
-    std::unique_ptr<webrtc::DesktopCapturer> capturer)
-    : desktop_capturer_(std::move(capturer)), weak_factory_(this) {
-  DCHECK(desktop_capturer_);
-
-  // Disable video adaptation since we don't intend to use it.
-  set_enable_video_adapter(false);
-}
-
-WebrtcVideoCapturerAdapter::~WebrtcVideoCapturerAdapter() {
-  DCHECK(!capture_timer_);
-}
-
-void WebrtcVideoCapturerAdapter::SetSizeCallback(
-    const VideoStream::SizeCallback& size_callback) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  size_callback_ = size_callback;
-}
-
-base::WeakPtr<WebrtcVideoCapturerAdapter>
-WebrtcVideoCapturerAdapter::GetWeakPtr() {
-  return weak_factory_.GetWeakPtr();
-}
-
-bool WebrtcVideoCapturerAdapter::GetBestCaptureFormat(
-    const cricket::VideoFormat& desired,
-    cricket::VideoFormat* best_format) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  // The |capture_format| passed to Start() is always ignored, so copy
-  // |best_format| to |desired_format|.
-  *best_format = desired;
-  return true;
-}
-
-cricket::CaptureState WebrtcVideoCapturerAdapter::Start(
-    const cricket::VideoFormat& capture_format) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(!capture_timer_);
-
-  if (!desktop_capturer_) {
-    VLOG(1) << "WebrtcVideoCapturerAdapter failed to start.";
-    return cricket::CS_FAILED;
-  }
-
-  desktop_capturer_->Start(this);
-
-  capture_timer_.reset(new base::RepeatingTimer());
-  capture_timer_->Start(FROM_HERE,
-                        base::TimeDelta::FromSeconds(1) / kFramesPerSec, this,
-                        &WebrtcVideoCapturerAdapter::CaptureNextFrame);
-
-  return cricket::CS_RUNNING;
-}
-
-bool WebrtcVideoCapturerAdapter::PauseCapturer(bool pause) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  if (pause) {
-    if (paused_)
-      return true;
-
-    bool running = capture_state() == cricket::CS_STARTING ||
-                   capture_state() == cricket::CS_RUNNING;
-
-    DCHECK_EQ(running, IsRunning());
-
-    if (!running) {
-      LOG(ERROR)
-          << "Cannot pause WebrtcVideoCapturerAdapter.";
-      return false;
-    }
-
-    capture_timer_->Stop();
-    paused_ = true;
-
-    VLOG(1) << "WebrtcVideoCapturerAdapter paused.";
-
-    return true;
-  } else {  // Unpausing.
-    if (!paused_ || !GetCaptureFormat() || !capture_timer_) {
-      LOG(ERROR) << "Cannot unpause WebrtcVideoCapturerAdapter.";
-      return false;
-    }
-
-    capture_timer_->Start(FROM_HERE,
-                          base::TimeDelta::FromMicroseconds(
-                              GetCaptureFormat()->interval /
-                              (base::Time::kNanosecondsPerMicrosecond)),
-                          this,
-                          &WebrtcVideoCapturerAdapter::CaptureNextFrame);
-    paused_ = false;
-
-    VLOG(1) << "WebrtcVideoCapturerAdapter unpaused.";
-  }
-  return true;
-}
-
-void WebrtcVideoCapturerAdapter::Stop() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK_NE(capture_state(), cricket::CS_STOPPED);
-
-  capture_timer_.reset();
-  desktop_capturer_.reset();
-
-  SetCaptureFormat(nullptr);
-  SetCaptureState(cricket::CS_STOPPED);
-
-  VLOG(1) << "WebrtcVideoCapturerAdapter stopped.";
-}
-
-bool WebrtcVideoCapturerAdapter::IsRunning() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  return capture_timer_->IsRunning();
-}
-
-bool WebrtcVideoCapturerAdapter::IsScreencast() const {
-  return true;
-}
-
-bool WebrtcVideoCapturerAdapter::GetPreferredFourccs(
-    std::vector<uint32_t>* fourccs) {
-  return false;
-}
-
-webrtc::SharedMemory* WebrtcVideoCapturerAdapter::CreateSharedMemory(
-    size_t size) {
-  return nullptr;
-}
-
-void WebrtcVideoCapturerAdapter::OnCaptureCompleted(
-    webrtc::DesktopFrame* frame) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  DCHECK(capture_pending_);
-  capture_pending_ = false;
-
-  if (!frame)
-    return;
-
-  std::unique_ptr<webrtc::DesktopFrame> owned_frame(frame);
-
-  // TODO(sergeyu): Currently the adapter keeps generating frames even when
-  // nothing is changing on the screen. This is necessary because the video
-  // sender drops frames. Obviously this is a suboptimal. The sending code in
-  // WebRTC needs to have some mechanism to notify when the bandwidth is
-  // exceeded, so the capturer can adapt frame rate.
-
-  webrtc::DesktopVector dpi =
-      frame->dpi().is_zero() ? webrtc::DesktopVector(kDefaultDpi, kDefaultDpi)
-                             : frame->dpi();
-  if (!frame_size_.equals(frame->size()) || !frame_dpi_.equals(dpi)) {
-    frame_size_ = frame->size();
-    frame_dpi_ = dpi;
-    if (!size_callback_.is_null())
-      size_callback_.Run(frame_size_, frame_dpi_);
-  }
-
-  if (!yuv_frame_ ||
-      !frame_size_.equals(
-          webrtc::DesktopSize(yuv_frame_->width(), yuv_frame_->height()))) {
-    yuv_frame_ = new rtc::RefCountedObject<webrtc::I420Buffer>(
-        frame_size_.width(), frame_size_.height());
-    // Set updated_region so the whole frame is converted to YUV below.
-    frame->mutable_updated_region()->SetRect(
-        webrtc::DesktopRect::MakeSize(frame_size_));
-  }
-
-  if (!yuv_frame_->HasOneRef()) {
-    // Frame is still used, typically by the encoder. We have to make
-    // a copy before modifying it.
-    // TODO(sergeyu): This will copy the buffer if it's being used.
-    // Optimize it by keeping a queue of frames.
-    yuv_frame_ = webrtc::I420Buffer::Copy(yuv_frame_);
-  }
-
-  for (webrtc::DesktopRegion::Iterator i(frame->updated_region()); !i.IsAtEnd();
-       i.Advance()) {
-    int left = i.rect().left();
-    int top = i.rect().top();
-    int width = i.rect().width();
-    int height = i.rect().height();
-
-    if (left % 2 == 1) {
-      --left;
-      ++width;
-    }
-    if (top % 2 == 1) {
-      --top;
-      ++height;
-    }
-
-    int y_stride = yuv_frame_->stride(webrtc::kYPlane);
-    int u_stride = yuv_frame_->stride(webrtc::kUPlane);
-    int v_stride = yuv_frame_->stride(webrtc::kVPlane);
-    libyuv::ARGBToI420(
-        frame->data() + frame->stride() * top +
-            left * webrtc::DesktopFrame::kBytesPerPixel,
-        frame->stride(),
-        yuv_frame_->MutableData(webrtc::kYPlane) + y_stride * top + left,
-        y_stride, yuv_frame_->MutableData(webrtc::kUPlane) +
-                      u_stride * top / 2 + left / 2,
-        u_stride, yuv_frame_->MutableData(webrtc::kVPlane) +
-                      v_stride * top / 2 + left / 2,
-        v_stride, width, height);
-  }
-
-  cricket::WebRtcVideoFrame video_frame(
-      yuv_frame_, (base::TimeTicks::Now() - base::TimeTicks()) /
-                      base::TimeDelta::FromMicroseconds(1) * 1000,
-      webrtc::kVideoRotation_0);
-
-  OnFrame(this, &video_frame);
-}
-
-void WebrtcVideoCapturerAdapter::CaptureNextFrame() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-
-  if (capture_pending_)
-    return;
-  capture_pending_ = true;
-  desktop_capturer_->Capture(webrtc::DesktopRegion());
-}
-
-}  // namespace protocol
-}  // namespace remoting