remoting/host/video_frame_pump.h

   1 // Copyright 2015 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 #ifndef REMOTING_HOST_VIDEO_FRAME_PUMP_H_
   6 #define REMOTING_HOST_VIDEO_FRAME_PUMP_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/threading/thread_checker.h"
  12 #include "base/time/time.h"
  13 #include "base/timer/timer.h"
  14 #include "remoting/codec/video_encoder.h"
  15 #include "remoting/host/capture_scheduler.h"
  16 #include "remoting/proto/video.pb.h"
  17 #include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"
  18
  19 namespace base {
  20 class SingleThreadTaskRunner;
  21 }  // namespace base
  22
  23 namespace remoting {
  24
  25 namespace protocol {
  26 class VideoFeedbackStub;
  27 class VideoStub;
  28 }  // namespace protocol
  29
  30 // Class responsible for scheduling frame captures from a screen capturer.,
  31 // delivering them to a VideoEncoder to encode, and
  32 // finally passing the encoded video packets to the specified VideoStub to send
  33 // on the network.
  34 //
  35 // THREADING
  36 //
  37 // This class is supplied TaskRunners to use for capture, encode and network
  38 // operations.  Capture, encode and network transmission tasks are interleaved
  39 // as illustrated below:
  40 //
  41 // |       CAPTURE       ENCODE     NETWORK
  42 // |    .............
  43 // |    .  Capture  .
  44 // |    .............
  45 // |                  ............
  46 // |                  .          .
  47 // |    ............. .          .
  48 // |    .  Capture  . .  Encode  .
  49 // |    ............. .          .
  50 // |                  .          .
  51 // |                  ............
  52 // |    ............. ............ ..........
  53 // |    .  Capture  . .          . .  Send  .
  54 // |    ............. .          . ..........
  55 // |                  .  Encode  .
  56 // |                  .          .
  57 // |                  .          .
  58 // |                  ............
  59 // | Time
  60 // v
  61 //
  62 // VideoFramePump would ideally schedule captures so as to saturate the slowest
  63 // of the capture, encode and network processes.  However, it also needs to
  64 // rate-limit captures to avoid overloading the host system, either by consuming
  65 // too much CPU, or hogging the host's graphics subsystem.
  66 class VideoFramePump : public webrtc::DesktopCapturer::Callback {
  67  public:
  68   // Enables timestamps for generated frames. Used for testing.
  69   static void EnableTimestampsForTests();
  70
  71   // Creates a VideoFramePump running capture, encode and network tasks on the
  72   // supplied TaskRunners. Video will be pumped to |video_stub|, which must
  73   // outlive the pump..
  74   VideoFramePump(
  75       scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner,
  76       scoped_ptr<webrtc::DesktopCapturer> capturer,
  77       scoped_ptr<VideoEncoder> encoder,
  78       protocol::VideoStub* video_stub);
  79   ~VideoFramePump() override;
  80
  81   // Pauses or resumes scheduling of frame captures.  Pausing/resuming captures
  82   // only affects capture scheduling and does not stop/start the capturer.
  83   void Pause(bool pause);
  84
  85   // Updates event timestamp from the last event received from the client. This
  86   // value is sent back to the client for roundtrip latency estimates.
  87   void SetLatestEventTimestamp(int64 latest_event_timestamp);
  88
  89   // Sets whether the video encoder should be requested to encode losslessly,
  90   // or to use a lossless color space (typically requiring higher bandwidth).
  91   void SetLosslessEncode(bool want_lossless);
  92   void SetLosslessColor(bool want_lossless);
  93
  94   protocol::VideoFeedbackStub* video_feedback_stub() {
  95     return &capture_scheduler_;
  96   }
  97
  98  private:
  99   // webrtc::DesktopCapturer::Callback interface.
 100   webrtc::SharedMemory* CreateSharedMemory(size_t size) override;
 101   void OnCaptureCompleted(webrtc::DesktopFrame* frame) override;
 102
 103   // Callback for CaptureScheduler.
 104   void CaptureNextFrame();
 105
 106   // Sends encoded frame
 107   void SendEncodedFrame(int64 latest_event_timestamp,
 108                         base::TimeTicks timestamp,
 109                         scoped_ptr<VideoPacket> packet);
 110
 111   // Callback passed to |video_stub_|.
 112   void OnVideoPacketSent();
 113
 114   // Called by |keep_alive_timer_|.
 115   void SendKeepAlivePacket();
 116
 117   // Callback for |video_stub_| called after a keep-alive packet is sent.
 118   void OnKeepAlivePacketSent();
 119
 120   // Task runner used to run |encoder_|.
 121   scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner_;
 122
 123   // Capturer used to capture the screen.
 124   scoped_ptr<webrtc::DesktopCapturer> capturer_;
 125
 126   // Used to encode captured frames. Always accessed on the encode thread.
 127   scoped_ptr<VideoEncoder> encoder_;
 128
 129   // Interface through which video frames are passed to the client.
 130   protocol::VideoStub* video_stub_;
 131
 132   // Timer used to ensure that we send empty keep-alive frames to the client
 133   // even when the video stream is paused or encoder is busy.
 134   base::Timer keep_alive_timer_;
 135
 136   // CaptureScheduler calls CaptureNextFrame() whenever a new frame needs to be
 137   // captured.
 138   CaptureScheduler capture_scheduler_;
 139
 140   // Number updated by the caller to trace performance.
 141   int64 latest_event_timestamp_;
 142
 143   base::ThreadChecker thread_checker_;
 144
 145   base::WeakPtrFactory<VideoFramePump> weak_factory_;
 146
 147   DISALLOW_COPY_AND_ASSIGN(VideoFramePump);
 148 };
 149
 150 }  // namespace remoting
 151
 152 #endif  // REMOTING_HOST_VIDEO_FRAME_PUMP_H_