media/renderers/video_renderer_impl.h

// Copyright 2013 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.

#ifndef MEDIA_RENDERERS_VIDEO_RENDERER_IMPL_H_
#define MEDIA_RENDERERS_VIDEO_RENDERER_IMPL_H_

#include <deque>

#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/condition_variable.h"
#include "base/synchronization/lock.h"
#include "base/threading/platform_thread.h"
#include "base/timer/timer.h"
#include "media/base/decryptor.h"
#include "media/base/demuxer_stream.h"
#include "media/base/media_log.h"
#include "media/base/pipeline_status.h"
#include "media/base/video_decoder.h"
#include "media/base/video_frame.h"
#include "media/base/video_renderer.h"
#include "media/base/video_renderer_sink.h"
#include "media/filters/decoder_stream.h"
#include "media/filters/video_renderer_algorithm.h"
#include "media/renderers/gpu_video_accelerator_factories.h"
#include "media/video/gpu_memory_buffer_video_frame_pool.h"

namespace base {
class SingleThreadTaskRunner;
class TickClock;
}

namespace media {

// VideoRendererImpl creates its own thread for the sole purpose of timing frame
// presentation.  It handles reading from the VideoFrameStream and stores the
// results in a queue of decoded frames and executing a callback when a frame is
// ready for rendering.
class MEDIA_EXPORT VideoRendererImpl
    : public VideoRenderer,
      public NON_EXPORTED_BASE(VideoRendererSink::RenderCallback),
      public base::PlatformThread::Delegate {
 public:
  // |decoders| contains the VideoDecoders to use when initializing.
  //
  // Implementors should avoid doing any sort of heavy work in this method and
  // instead post a task to a common/worker thread to handle rendering.  Slowing
  // down the video thread may result in losing synchronization with audio.
  //
  // Setting |drop_frames_| to true causes the renderer to drop expired frames.
  VideoRendererImpl(
      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
      VideoRendererSink* sink,
      ScopedVector<VideoDecoder> decoders,
      bool drop_frames,
      const scoped_refptr<GpuVideoAcceleratorFactories>& gpu_factories,
      const scoped_refptr<MediaLog>& media_log);
  ~VideoRendererImpl() override;

  // VideoRenderer implementation.
  void Initialize(DemuxerStream* stream,
                  const PipelineStatusCB& init_cb,
                  const SetDecryptorReadyCB& set_decryptor_ready_cb,
                  const StatisticsCB& statistics_cb,
                  const BufferingStateCB& buffering_state_cb,
                  const base::Closure& ended_cb,
                  const PipelineStatusCB& error_cb,
                  const TimeSource::WallClockTimeCB& wall_clock_time_cb,
                  const base::Closure& waiting_for_decryption_key_cb) override;
  void Flush(const base::Closure& callback) override;
  void StartPlayingFrom(base::TimeDelta timestamp) override;
  void OnTimeStateChanged(bool time_progressing) override;

  // PlatformThread::Delegate implementation.
  void ThreadMain() override;

  void SetTickClockForTesting(scoped_ptr<base::TickClock> tick_clock);

  // VideoRendererSink::RenderCallback implementation.
  scoped_refptr<VideoFrame> Render(base::TimeTicks deadline_min,
                                   base::TimeTicks deadline_max,
                                   bool background_rendering) override;
  void OnFrameDropped() override;

  void disable_new_video_renderer_for_testing() {
    use_new_video_renderering_path_ = false;
  }

 private:
  // Creates a dedicated |thread_| for video rendering.
  void CreateVideoThread();

  // Callback for |video_frame_stream_| initialization.
  void OnVideoFrameStreamInitialized(bool success);

  // Callback for |video_frame_stream_| to deliver decoded video frames and
  // report video decoding status.
  void FrameReady(VideoFrameStream::Status status,
                  const scoped_refptr<VideoFrame>& frame);

  // Helper method for adding a frame to |ready_frames_|.
  void AddReadyFrame_Locked(const scoped_refptr<VideoFrame>& frame);

  // Helper method that schedules an asynchronous read from the
  // |video_frame_stream_| as long as there isn't a pending read and we have
  // capacity.
  void AttemptRead();
  void AttemptRead_Locked();

  // Called when VideoFrameStream::Reset() completes.
  void OnVideoFrameStreamResetDone();

  // Runs |paint_cb_| with the next frame from |ready_frames_|.
  //
  // A read is scheduled to replace the frame.
  void PaintNextReadyFrame_Locked();

  // Drops the next frame from |ready_frames_| and runs |statistics_cb_|.
  //
  // A read is scheduled to replace the frame.
  void DropNextReadyFrame_Locked();

  // Returns true if the renderer has enough data for playback purposes.
  // Note that having enough data may be due to reaching end of stream.
  bool HaveEnoughData_Locked();
  void TransitionToHaveEnough_Locked();
  void TransitionToHaveNothing();

  // Runs |statistics_cb_| with |frames_decoded_| and |frames_dropped_|, resets
  // them to 0, and then waits on |frame_available_| for up to the
  // |wait_duration|.
  void UpdateStatsAndWait_Locked(base::TimeDelta wait_duration);

  // Called after we've painted the first frame.  If |time_progressing_| is
  // false it Stop() on |sink_|.
  void MaybeStopSinkAfterFirstPaint();

  // Returns true if there is no more room for additional buffered frames.
  bool HaveReachedBufferingCap();

  // Starts or stops |sink_| respectively. Do not call while |lock_| is held.
  void StartSink();
  void StopSink();

  // Fires |ended_cb_| if there are no remaining usable frames and
  // |received_end_of_stream_| is true.  Sets |rendered_end_of_stream_| if it
  // does so.  Returns algorithm_->EffectiveFramesQueued().
  size_t MaybeFireEndedCallback();

  // Helper method for converting a single media timestamp to wall clock time.
  base::TimeTicks ConvertMediaTimestamp(base::TimeDelta media_timestamp);

  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;

  // Enables the use of VideoRendererAlgorithm and VideoRendererSink for frame
  // rendering instead of using a thread in a sleep-loop.  Set via the command
  // line flag kEnableNewVideoRenderer or via test methods.
  bool use_new_video_renderering_path_;

  // Sink which calls into VideoRendererImpl via Render() for video frames.  Do
  // not call any methods on the sink while |lock_| is held or the two threads
  // might deadlock. Do not call Start() or Stop() on the sink directly, use
  // StartSink() and StopSink() to ensure background rendering is started.
  VideoRendererSink* const sink_;
  bool sink_started_;

  // Used for accessing data members.
  base::Lock lock_;

  // Provides video frames to VideoRendererImpl.
  scoped_ptr<VideoFrameStream> video_frame_stream_;

  // Pool of GpuMemoryBuffers and resources used to create hardware frames.
  scoped_ptr<GpuMemoryBufferVideoFramePool> gpu_memory_buffer_pool_;

  // Flag indicating low-delay mode.
  bool low_delay_;

  // Queue of incoming frames yet to be painted.
  typedef std::deque<scoped_refptr<VideoFrame>> VideoFrameQueue;
  VideoFrameQueue ready_frames_;

  // Keeps track of whether we received the end of stream buffer and finished
  // rendering.
  bool received_end_of_stream_;
  bool rendered_end_of_stream_;

  // Used to signal |thread_| as frames are added to |frames_|.  Rule of thumb:
  // always check |state_| to see if it was set to STOPPED after waking up!
  base::ConditionVariable frame_available_;

  // Important detail: being in kPlaying doesn't imply that video is being
  // rendered. Rather, it means that the renderer is ready to go. The actual
  // rendering of video is controlled by time advancing via |get_time_cb_|.
  //
  //   kUninitialized
  //         | Initialize()
  //         |
  //         V
  //    kInitializing
  //         | Decoders initialized
  //         |
  //         V            Decoders reset
  //      kFlushed <------------------ kFlushing
  //         | StartPlayingFrom()         ^
  //         |                            |
  //         |                            | Flush()
  //         `---------> kPlaying --------'
  enum State {
    kUninitialized,
    kInitializing,
    kFlushing,
    kFlushed,
    kPlaying
  };
  State state_;

  // Video thread handle.
  base::PlatformThreadHandle thread_;

  // Keep track of the outstanding read on the VideoFrameStream. Flushing can
  // only complete once the read has completed.
  bool pending_read_;

  bool drop_frames_;

  BufferingState buffering_state_;

  // Playback operation callbacks.
  base::Closure flush_cb_;

  // Event callbacks.
  PipelineStatusCB init_cb_;
  StatisticsCB statistics_cb_;
  BufferingStateCB buffering_state_cb_;
  base::Closure ended_cb_;
  PipelineStatusCB error_cb_;
  TimeSource::WallClockTimeCB wall_clock_time_cb_;

  base::TimeDelta start_timestamp_;

  // Embedder callback for notifying a new frame is available for painting.
  PaintCB paint_cb_;

  // The wallclock times of the last frame removed from the |ready_frames_|
  // queue, either for calling |paint_cb_| or for dropping. Set to null during
  // flushing.
  base::TimeTicks last_media_time_;

  // Equivalent to |last_media_time_| + the estimated duration of the frame.
  base::TimeTicks latest_possible_paint_time_;

  // Keeps track of the number of frames decoded and dropped since the
  // last call to |statistics_cb_|. These must be accessed under lock.
  int frames_decoded_;
  int frames_dropped_;

  bool is_shutting_down_;

  scoped_ptr<base::TickClock> tick_clock_;

  // Algorithm for selecting which frame to render; manages frames and all
  // timing related information.
  scoped_ptr<VideoRendererAlgorithm> algorithm_;

  // Indicates that Render() was called with |background_rendering| set to true,
  // so we've entered a background rendering mode where dropped frames are not
  // counted.
  bool was_background_rendering_;

  // Indicates whether or not media time is currently progressing or not.
  bool time_progressing_;

  // Indicates that Render() should only render the first frame and then request
  // that the sink be stopped.  |posted_maybe_stop_after_first_paint_| is used
  // to avoid repeated task posts.
  bool render_first_frame_and_stop_;
  bool posted_maybe_stop_after_first_paint_;

  // NOTE: Weak pointers must be invalidated before all other member variables.
  base::WeakPtrFactory<VideoRendererImpl> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(VideoRendererImpl);
};

}  // namespace media

#endif  // MEDIA_RENDERERS_VIDEO_RENDERER_IMPL_H_