path: root/media/renderers/video_renderer_impl.cc

// 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.

#include "media/renderers/video_renderer_impl.h"

#include "base/bind.h"
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/location.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/platform_thread.h"
#include "base/time/default_tick_clock.h"
#include "base/trace_event/trace_event.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/buffers.h"
#include "media/base/limits.h"
#include "media/base/media_switches.h"
#include "media/base/pipeline.h"
#include "media/base/video_frame.h"

namespace media {

VideoRendererImpl::VideoRendererImpl(
    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
    VideoRendererSink* sink,
    ScopedVector<VideoDecoder> decoders,
    bool drop_frames,
    const scoped_refptr<MediaLog>& media_log)
    : task_runner_(task_runner),
      use_new_video_renderering_path_(
          !base::CommandLine::ForCurrentProcess()->HasSwitch(
              switches::kDisableNewVideoRenderer)),
      sink_(sink),
      sink_started_(false),
      video_frame_stream_(
          new VideoFrameStream(task_runner, decoders.Pass(), media_log)),
      low_delay_(false),
      received_end_of_stream_(false),
      rendered_end_of_stream_(false),
      frame_available_(&lock_),
      state_(kUninitialized),
      thread_(),
      pending_read_(false),
      drop_frames_(drop_frames),
      buffering_state_(BUFFERING_HAVE_NOTHING),
      frames_decoded_(0),
      frames_dropped_(0),
      is_shutting_down_(false),
      tick_clock_(new base::DefaultTickClock()),
      was_background_rendering_(false),
      time_progressing_(false),
      render_first_frame_and_stop_(false),
      weak_factory_(this) {
}

VideoRendererImpl::~VideoRendererImpl() {
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (!use_new_video_renderering_path_) {
    base::AutoLock auto_lock(lock_);
    is_shutting_down_ = true;
    frame_available_.Signal();
  }

  if (!thread_.is_null())
    base::PlatformThread::Join(thread_);

  if (!init_cb_.is_null())
    base::ResetAndReturn(&init_cb_).Run(PIPELINE_ERROR_ABORT);

  if (!flush_cb_.is_null())
    base::ResetAndReturn(&flush_cb_).Run();

  if (use_new_video_renderering_path_ && sink_started_)
    StopSink();
}

void VideoRendererImpl::Flush(const base::Closure& callback) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (use_new_video_renderering_path_ && sink_started_)
    StopSink();

  base::AutoLock auto_lock(lock_);
  DCHECK_EQ(state_, kPlaying);
  flush_cb_ = callback;
  state_ = kFlushing;

  // This is necessary if the |video_frame_stream_| has already seen an end of
  // stream and needs to drain it before flushing it.
  ready_frames_.clear();
  if (buffering_state_ != BUFFERING_HAVE_NOTHING) {
    buffering_state_ = BUFFERING_HAVE_NOTHING;
    buffering_state_cb_.Run(BUFFERING_HAVE_NOTHING);
  }
  received_end_of_stream_ = false;
  rendered_end_of_stream_ = false;

  if (use_new_video_renderering_path_)
    algorithm_->Reset();

  video_frame_stream_->Reset(
      base::Bind(&VideoRendererImpl::OnVideoFrameStreamResetDone,
                 weak_factory_.GetWeakPtr()));
}

void VideoRendererImpl::StartPlayingFrom(base::TimeDelta timestamp) {
  DVLOG(1) << __FUNCTION__ << "(" << timestamp.InMicroseconds() << ")";
  DCHECK(task_runner_->BelongsToCurrentThread());
  base::AutoLock auto_lock(lock_);
  DCHECK_EQ(state_, kFlushed);
  DCHECK(!pending_read_);
  DCHECK(ready_frames_.empty());
  DCHECK_EQ(buffering_state_, BUFFERING_HAVE_NOTHING);

  state_ = kPlaying;
  start_timestamp_ = timestamp;
  AttemptRead_Locked();
}

void VideoRendererImpl::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 WallClockTimeCB& wall_clock_time_cb,
    const base::Closure& waiting_for_decryption_key_cb) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  base::AutoLock auto_lock(lock_);
  DCHECK(stream);
  DCHECK_EQ(stream->type(), DemuxerStream::VIDEO);
  DCHECK(!init_cb.is_null());
  DCHECK(!statistics_cb.is_null());
  DCHECK(!buffering_state_cb.is_null());
  DCHECK(!ended_cb.is_null());
  DCHECK(!wall_clock_time_cb.is_null());
  DCHECK_EQ(kUninitialized, state_);
  DCHECK(!render_first_frame_and_stop_);
  DCHECK(!was_background_rendering_);
  DCHECK(!time_progressing_);

  low_delay_ = (stream->liveness() == DemuxerStream::LIVENESS_LIVE);

  // Always post |init_cb_| because |this| could be destroyed if initialization
  // failed.
  init_cb_ = BindToCurrentLoop(init_cb);

  statistics_cb_ = statistics_cb;
  buffering_state_cb_ = buffering_state_cb;
  paint_cb_ = base::Bind(&VideoRendererSink::PaintFrameUsingOldRenderingPath,
                         base::Unretained(sink_));
  ended_cb_ = ended_cb;
  error_cb_ = error_cb;
  wall_clock_time_cb_ = wall_clock_time_cb;
  state_ = kInitializing;

  video_frame_stream_->Initialize(
      stream, base::Bind(&VideoRendererImpl::OnVideoFrameStreamInitialized,
                         weak_factory_.GetWeakPtr()),
      set_decryptor_ready_cb, statistics_cb, waiting_for_decryption_key_cb);
}

scoped_refptr<VideoFrame> VideoRendererImpl::Render(
    base::TimeTicks deadline_min,
    base::TimeTicks deadline_max,
    bool background_rendering) {
  base::AutoLock auto_lock(lock_);
  DCHECK(use_new_video_renderering_path_);
  DCHECK_EQ(state_, kPlaying);

  size_t frames_dropped = 0;
  scoped_refptr<VideoFrame> result =
      algorithm_->Render(deadline_min, deadline_max, &frames_dropped);

  // Due to how the |algorithm_| holds frames, this should never be null if
  // we've had a proper startup sequence.
  DCHECK(result);

  // Declare HAVE_NOTHING if we reach a state where we can't progress playback
  // any further.  We don't want to do this if we've already done so, reached
  // end of stream, or have frames available.  We also don't want to do this in
  // background rendering mode unless this isn't the first background render
  // tick and we haven't seen any decoded frames since the last one.
  const size_t effective_frames = MaybeFireEndedCallback();
  if (buffering_state_ == BUFFERING_HAVE_ENOUGH && !received_end_of_stream_ &&
      !effective_frames && (!background_rendering ||
                            (!frames_decoded_ && was_background_rendering_))) {
    // Do not set |buffering_state_| here as the lock in FrameReady() may be
    // held already and it fire the state changes in the wrong order.
    task_runner_->PostTask(
        FROM_HERE, base::Bind(&VideoRendererImpl::TransitionToHaveNothing,
                              weak_factory_.GetWeakPtr()));
  }

  // We don't count dropped frames in the background to avoid skewing the count
  // and impacting JavaScript visible metrics used by web developers.
  //
  // Just after resuming from background rendering, we also don't count the
  // dropped frames since they are likely just dropped due to being too old.
  if (!background_rendering && !was_background_rendering_)
    frames_dropped_ += frames_dropped;
  UpdateStatsAndWait_Locked(base::TimeDelta());
  was_background_rendering_ = background_rendering;

  // After painting the first frame, if playback hasn't started, we request that
  // the sink be stopped.  OnTimeStateChanged() will clear this flag if time
  // starts before we get here and MaybeStopSinkAfterFirstPaint() will ignore
  // this request if time starts before the call executes.
  if (render_first_frame_and_stop_) {
    task_runner_->PostTask(
        FROM_HERE, base::Bind(&VideoRendererImpl::MaybeStopSinkAfterFirstPaint,
                              weak_factory_.GetWeakPtr()));
  }

  // Always post this task, it will acquire new frames if necessary, reset the
  // background rendering timer, and more.
  task_runner_->PostTask(FROM_HERE, base::Bind(&VideoRendererImpl::AttemptRead,
                                               weak_factory_.GetWeakPtr()));

  return result;
}

void VideoRendererImpl::OnFrameDropped() {
  base::AutoLock auto_lock(lock_);
  DCHECK(use_new_video_renderering_path_);
  algorithm_->OnLastFrameDropped();
}

void VideoRendererImpl::CreateVideoThread() {
  // This may fail and cause a crash if there are too many threads created in
  // the current process. See http://crbug.com/443291
  CHECK(base::PlatformThread::Create(0, this, &thread_));

#if defined(OS_WIN)
  // Bump up our priority so our sleeping is more accurate.
  // TODO(scherkus): find out if this is necessary, but it seems to help.
  ::SetThreadPriority(thread_.platform_handle(), THREAD_PRIORITY_ABOVE_NORMAL);
#endif  // defined(OS_WIN)
}

void VideoRendererImpl::OnVideoFrameStreamInitialized(bool success) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  base::AutoLock auto_lock(lock_);
  DCHECK_EQ(state_, kInitializing);

  if (!success) {
    state_ = kUninitialized;
    base::ResetAndReturn(&init_cb_).Run(DECODER_ERROR_NOT_SUPPORTED);
    return;
  }

  // We're all good!  Consider ourselves flushed. (ThreadMain() should never
  // see us in the kUninitialized state).
  // Since we had an initial Preroll(), we consider ourself flushed, because we
  // have not populated any buffers yet.
  state_ = kFlushed;

  if (use_new_video_renderering_path_) {
    algorithm_.reset(new VideoRendererAlgorithm(wall_clock_time_cb_));
    if (!drop_frames_)
      algorithm_->disable_frame_dropping();
  } else {
    CreateVideoThread();
  }

  base::ResetAndReturn(&init_cb_).Run(PIPELINE_OK);
}

// PlatformThread::Delegate implementation.
void VideoRendererImpl::ThreadMain() {
  DCHECK(!use_new_video_renderering_path_);
  base::PlatformThread::SetName("CrVideoRenderer");

  // The number of milliseconds to idle when we do not have anything to do.
  // Nothing special about the value, other than we're being more OS-friendly
  // than sleeping for 1 millisecond.
  //
  // TODO(scherkus): switch to pure event-driven frame timing instead of this
  // kIdleTimeDelta business http://crbug.com/106874
  const base::TimeDelta kIdleTimeDelta =
      base::TimeDelta::FromMilliseconds(10);

  for (;;) {
    base::AutoLock auto_lock(lock_);

    // Thread exit condition.
    if (is_shutting_down_)
      return;

    // Remain idle as long as we're not playing.
    if (state_ != kPlaying || buffering_state_ != BUFFERING_HAVE_ENOUGH) {
      UpdateStatsAndWait_Locked(kIdleTimeDelta);
      continue;
    }

    base::TimeTicks now = tick_clock_->NowTicks();

    // Remain idle until we have the next frame ready for rendering.
    if (ready_frames_.empty()) {
      base::TimeDelta wait_time = kIdleTimeDelta;
      if (received_end_of_stream_) {
        if (!rendered_end_of_stream_) {
          rendered_end_of_stream_ = true;
          task_runner_->PostTask(FROM_HERE, ended_cb_);
        }
      } else if (now >= latest_possible_paint_time_) {
        // Declare HAVE_NOTHING if we don't have another frame by the time we
        // are ready to paint the next one.
        buffering_state_ = BUFFERING_HAVE_NOTHING;
        task_runner_->PostTask(
            FROM_HERE, base::Bind(buffering_state_cb_, BUFFERING_HAVE_NOTHING));
      } else {
        wait_time = std::min(kIdleTimeDelta, latest_possible_paint_time_ - now);
      }

      UpdateStatsAndWait_Locked(wait_time);
      continue;
    }

    base::TimeTicks target_paint_time =
        wall_clock_time_cb_.Run(ready_frames_.front()->timestamp());

    // If media time has stopped, don't attempt to paint any more frames.
    if (target_paint_time.is_null()) {
      UpdateStatsAndWait_Locked(kIdleTimeDelta);
      continue;
    }

    // Deadline is defined as the duration between this frame and the next
    // frame, using the delta between this frame and the previous frame as the
    // assumption for frame duration.
    //
    // TODO(scherkus): This can be vastly improved. Use a histogram to measure
    // the accuracy of our frame timing code. http://crbug.com/149829
    if (last_media_time_.is_null()) {
      latest_possible_paint_time_ = now;
    } else {
      base::TimeDelta duration = target_paint_time - last_media_time_;
      latest_possible_paint_time_ = target_paint_time + duration;
    }

    // Remain idle until we've reached our target paint window.
    if (now < target_paint_time) {
      UpdateStatsAndWait_Locked(
          std::min(target_paint_time - now, kIdleTimeDelta));
      continue;
    }

    if (ready_frames_.size() > 1 && now > latest_possible_paint_time_ &&
        drop_frames_) {
      DropNextReadyFrame_Locked();
      continue;
    }

    // Congratulations! You've made it past the video frame timing gauntlet.
    //
    // At this point enough time has passed that the next frame that ready for
    // rendering.
    PaintNextReadyFrame_Locked();
  }
}

void VideoRendererImpl::SetTickClockForTesting(
    scoped_ptr<base::TickClock> tick_clock) {
  tick_clock_.swap(tick_clock);
}

void VideoRendererImpl::OnTimeStateChanged(bool time_progressing) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  time_progressing_ = time_progressing;

  // WARNING: Do not attempt to use |lock_| here as this may be a reentrant call
  // in response to callbacks firing above.

  if (!use_new_video_renderering_path_ || sink_started_ == time_progressing_)
    return;

  if (time_progressing_)
    StartSink();
  else
    StopSink();
}

void VideoRendererImpl::PaintNextReadyFrame_Locked() {
  DCHECK(!use_new_video_renderering_path_);
  lock_.AssertAcquired();

  scoped_refptr<VideoFrame> next_frame = ready_frames_.front();
  ready_frames_.pop_front();

  last_media_time_ = wall_clock_time_cb_.Run(next_frame->timestamp());

  paint_cb_.Run(next_frame);

  task_runner_->PostTask(
      FROM_HERE,
      base::Bind(&VideoRendererImpl::AttemptRead, weak_factory_.GetWeakPtr()));
}

void VideoRendererImpl::DropNextReadyFrame_Locked() {
  DCHECK(!use_new_video_renderering_path_);
  TRACE_EVENT0("media", "VideoRendererImpl:frameDropped");

  lock_.AssertAcquired();

  last_media_time_ =
      wall_clock_time_cb_.Run(ready_frames_.front()->timestamp());

  ready_frames_.pop_front();
  frames_dropped_++;

  task_runner_->PostTask(
      FROM_HERE,
      base::Bind(&VideoRendererImpl::AttemptRead, weak_factory_.GetWeakPtr()));
}

void VideoRendererImpl::FrameReady(VideoFrameStream::Status status,
                                   const scoped_refptr<VideoFrame>& frame) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  bool start_sink = false;
  {
    base::AutoLock auto_lock(lock_);
    DCHECK_NE(state_, kUninitialized);
    DCHECK_NE(state_, kFlushed);

    CHECK(pending_read_);
    pending_read_ = false;

    if (status == VideoFrameStream::DECODE_ERROR ||
        status == VideoFrameStream::DECRYPT_ERROR) {
      DCHECK(!frame.get());
      PipelineStatus error = PIPELINE_ERROR_DECODE;
      if (status == VideoFrameStream::DECRYPT_ERROR)
        error = PIPELINE_ERROR_DECRYPT;
      task_runner_->PostTask(FROM_HERE, base::Bind(error_cb_, error));
      return;
    }

    // Already-queued VideoFrameStream ReadCB's can fire after various state
    // transitions have happened; in that case just drop those frames
    // immediately.
    if (state_ == kFlushing)
      return;

    DCHECK_EQ(state_, kPlaying);

    // Can happen when demuxers are preparing for a new Seek().
    if (!frame.get()) {
      DCHECK_EQ(status, VideoFrameStream::DEMUXER_READ_ABORTED);
      return;
    }

    if (frame->end_of_stream()) {
      DCHECK(!received_end_of_stream_);
      received_end_of_stream_ = true;

      // See if we can fire EOS immediately instead of waiting for Render() or
      // to tick.  We also want to fire EOS if we have no frames and received
      // EOS.
      if (use_new_video_renderering_path_ &&
          (time_progressing_ || !algorithm_->frames_queued())) {
        MaybeFireEndedCallback();
      }
    } else {
      // Maintain the latest frame decoded so the correct frame is displayed
      // after prerolling has completed.
      if (frame->timestamp() <= start_timestamp_) {
        if (use_new_video_renderering_path_)
          algorithm_->Reset();
        ready_frames_.clear();
      }
      AddReadyFrame_Locked(frame);
    }

    // Signal buffering state if we've met our conditions for having enough
    // data.
    if (buffering_state_ != BUFFERING_HAVE_ENOUGH && HaveEnoughData_Locked()) {
      TransitionToHaveEnough_Locked();
      if (use_new_video_renderering_path_ && !sink_started_ &&
          !rendered_end_of_stream_) {
        start_sink = true;
        render_first_frame_and_stop_ = true;
      }
    }

    // Background rendering updates may not be ticking fast enough by itself to
    // remove expired frames, so give it a boost here by ensuring we don't exit
    // the decoding cycle too early.
    if (was_background_rendering_) {
      DCHECK(use_new_video_renderering_path_);
      algorithm_->RemoveExpiredFrames(tick_clock_->NowTicks());
    }

    // Always request more decoded video if we have capacity. This serves two
    // purposes:
    //   1) Prerolling while paused
    //   2) Keeps decoding going if video rendering thread starts falling behind
    AttemptRead_Locked();
  }

  // If time is progressing, the sink has already been started; this may be true
  // if we have previously underflowed, yet weren't stopped because of audio.
  if (use_new_video_renderering_path_ && start_sink) {
    DCHECK(!sink_started_);
    StartSink();
  }
}

bool VideoRendererImpl::HaveEnoughData_Locked() {
  DCHECK_EQ(state_, kPlaying);

  if (received_end_of_stream_ || !video_frame_stream_->CanReadWithoutStalling())
    return true;

  if (HaveReachedBufferingCap())
    return true;

  if (use_new_video_renderering_path_ && was_background_rendering_ &&
      frames_decoded_) {
    return true;
  }

  if (!low_delay_)
    return false;

  return ready_frames_.size() > 0 ||
         (use_new_video_renderering_path_ && algorithm_->frames_queued() > 0);
}

void VideoRendererImpl::TransitionToHaveEnough_Locked() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(buffering_state_, BUFFERING_HAVE_NOTHING);

  if (!ready_frames_.empty()) {
    DCHECK(!use_new_video_renderering_path_);
    // Because the clock might remain paused in for an undetermined amount
    // of time (e.g., seeking while paused), paint the first frame.
    PaintNextReadyFrame_Locked();
  }

  buffering_state_ = BUFFERING_HAVE_ENOUGH;
  buffering_state_cb_.Run(BUFFERING_HAVE_ENOUGH);
}

void VideoRendererImpl::TransitionToHaveNothing() {
  DCHECK(task_runner_->BelongsToCurrentThread());

  base::AutoLock auto_lock(lock_);
  if (buffering_state_ != BUFFERING_HAVE_ENOUGH || HaveEnoughData_Locked())
    return;

  buffering_state_ = BUFFERING_HAVE_NOTHING;
  buffering_state_cb_.Run(BUFFERING_HAVE_NOTHING);
}

void VideoRendererImpl::AddReadyFrame_Locked(
    const scoped_refptr<VideoFrame>& frame) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  lock_.AssertAcquired();
  DCHECK(!frame->end_of_stream());

  frames_decoded_++;

  if (use_new_video_renderering_path_) {
    algorithm_->EnqueueFrame(frame);
    return;
  }

  ready_frames_.push_back(frame);
  DCHECK_LE(ready_frames_.size(),
            static_cast<size_t>(limits::kMaxVideoFrames));

  // Avoid needlessly waking up |thread_| unless playing.
  if (state_ == kPlaying)
    frame_available_.Signal();
}

void VideoRendererImpl::AttemptRead() {
  base::AutoLock auto_lock(lock_);
  AttemptRead_Locked();
}

void VideoRendererImpl::AttemptRead_Locked() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  lock_.AssertAcquired();

  if (pending_read_ || received_end_of_stream_)
    return;

  if (HaveReachedBufferingCap())
    return;

  switch (state_) {
    case kPlaying:
      pending_read_ = true;
      video_frame_stream_->Read(base::Bind(&VideoRendererImpl::FrameReady,
                                           weak_factory_.GetWeakPtr()));
      return;

    case kUninitialized:
    case kInitializing:
    case kFlushing:
    case kFlushed:
      return;
  }
}

void VideoRendererImpl::OnVideoFrameStreamResetDone() {
  base::AutoLock auto_lock(lock_);
  DCHECK_EQ(kFlushing, state_);
  DCHECK(!pending_read_);
  DCHECK(ready_frames_.empty());
  DCHECK(!received_end_of_stream_);
  DCHECK(!rendered_end_of_stream_);
  DCHECK_EQ(buffering_state_, BUFFERING_HAVE_NOTHING);

  state_ = kFlushed;
  latest_possible_paint_time_ = last_media_time_ = base::TimeTicks();
  base::ResetAndReturn(&flush_cb_).Run();
}

void VideoRendererImpl::UpdateStatsAndWait_Locked(
    base::TimeDelta wait_duration) {
  lock_.AssertAcquired();
  DCHECK_GE(frames_decoded_, 0);
  DCHECK_GE(frames_dropped_, 0);

  if (frames_decoded_ || frames_dropped_) {
    PipelineStatistics statistics;
    statistics.video_frames_decoded = frames_decoded_;
    statistics.video_frames_dropped = frames_dropped_;
    task_runner_->PostTask(FROM_HERE, base::Bind(statistics_cb_, statistics));

    frames_decoded_ = 0;
    frames_dropped_ = 0;
  }

  if (wait_duration > base::TimeDelta())
    frame_available_.TimedWait(wait_duration);
}

void VideoRendererImpl::MaybeStopSinkAfterFirstPaint() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(use_new_video_renderering_path_);

  {
    base::AutoLock auto_lock(lock_);
    render_first_frame_and_stop_ = false;
  }

  if (!time_progressing_ && sink_started_)
    StopSink();
}

bool VideoRendererImpl::HaveReachedBufferingCap() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  if (use_new_video_renderering_path_) {
    // When the display rate is less than the frame rate, the effective frames
    // queued may be much smaller than the actual number of frames queued.  Here
    // we ensure that frames_queued() doesn't get excessive.
    return algorithm_->EffectiveFramesQueued() >=
               static_cast<size_t>(limits::kMaxVideoFrames) ||
           algorithm_->frames_queued() >=
               static_cast<size_t>(3 * limits::kMaxVideoFrames);
  }

  return ready_frames_.size() >= static_cast<size_t>(limits::kMaxVideoFrames);
}

void VideoRendererImpl::StartSink() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  sink_->Start(this);
  sink_started_ = true;
  was_background_rendering_ = false;
}

void VideoRendererImpl::StopSink() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  sink_->Stop();
  sink_started_ = false;
  was_background_rendering_ = false;
}

size_t VideoRendererImpl::MaybeFireEndedCallback() {
  // If there's only one frame in the video or Render() was never called, the
  // algorithm will have one frame linger indefinitely.  So in cases where the
  // frame duration is unknown and we've received EOS, fire it once we get down
  // to a single frame.
  const size_t effective_frames = algorithm_->EffectiveFramesQueued();

  if ((!effective_frames ||
       (algorithm_->frames_queued() == 1u &&
        algorithm_->average_frame_duration() == base::TimeDelta())) &&
      received_end_of_stream_ && !rendered_end_of_stream_) {
    rendered_end_of_stream_ = true;
    task_runner_->PostTask(FROM_HERE, ended_cb_);
  }

  return effective_frames;
}

}  // namespace media