media/renderers/renderer_impl.cc

// Copyright 2014 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/renderer_impl.h"

#include "base/bind.h"
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/location.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_number_conversions.h"
#include "media/base/audio_renderer.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/demuxer_stream_provider.h"
#include "media/base/media_switches.h"
#include "media/base/time_source.h"
#include "media/base/video_renderer.h"
#include "media/base/wall_clock_time_source.h"

namespace media {

// See |video_underflow_threshold_|.
static const int kDefaultVideoUnderflowThresholdMs = 3000;

RendererImpl::RendererImpl(
    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
    scoped_ptr<AudioRenderer> audio_renderer,
    scoped_ptr<VideoRenderer> video_renderer)
    : state_(STATE_UNINITIALIZED),
      task_runner_(task_runner),
      audio_renderer_(audio_renderer.Pass()),
      video_renderer_(video_renderer.Pass()),
      time_source_(NULL),
      time_ticking_(false),
      playback_rate_(0.0),
      audio_buffering_state_(BUFFERING_HAVE_NOTHING),
      video_buffering_state_(BUFFERING_HAVE_NOTHING),
      audio_ended_(false),
      video_ended_(false),
      cdm_context_(nullptr),
      underflow_disabled_for_testing_(false),
      clockless_video_playback_enabled_for_testing_(false),
      video_underflow_threshold_(
          base::TimeDelta::FromMilliseconds(kDefaultVideoUnderflowThresholdMs)),
      weak_factory_(this) {
  weak_this_ = weak_factory_.GetWeakPtr();
  DVLOG(1) << __FUNCTION__;

  // TODO(dalecurtis): Remove once experiments for http://crbug.com/470940 are
  // complete.
  int threshold_ms = 0;
  std::string threshold_ms_str(
      base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
          switches::kVideoUnderflowThresholdMs));
  if (base::StringToInt(threshold_ms_str, &threshold_ms) && threshold_ms > 0) {
    video_underflow_threshold_ =
        base::TimeDelta::FromMilliseconds(threshold_ms);
  }
}

RendererImpl::~RendererImpl() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  // Tear down in opposite order of construction as |video_renderer_| can still
  // need |time_source_| (which can be |audio_renderer_|) to be alive.
  video_renderer_.reset();
  audio_renderer_.reset();

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

void RendererImpl::Initialize(
    DemuxerStreamProvider* demuxer_stream_provider,
    const PipelineStatusCB& init_cb,
    const StatisticsCB& statistics_cb,
    const BufferingStateCB& buffering_state_cb,
    const base::Closure& ended_cb,
    const PipelineStatusCB& error_cb,
    const base::Closure& waiting_for_decryption_key_cb) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_UNINITIALIZED);
  DCHECK(!init_cb.is_null());
  DCHECK(!statistics_cb.is_null());
  DCHECK(!buffering_state_cb.is_null());
  DCHECK(!ended_cb.is_null());
  DCHECK(!error_cb.is_null());
  DCHECK(demuxer_stream_provider->GetStream(DemuxerStream::AUDIO) ||
         demuxer_stream_provider->GetStream(DemuxerStream::VIDEO));

  demuxer_stream_provider_ = demuxer_stream_provider;
  statistics_cb_ = statistics_cb;
  buffering_state_cb_ = buffering_state_cb;
  ended_cb_ = ended_cb;
  error_cb_ = error_cb;
  init_cb_ = init_cb;
  waiting_for_decryption_key_cb_ = waiting_for_decryption_key_cb;

  state_ = STATE_INITIALIZING;
  InitializeAudioRenderer();
}

void RendererImpl::SetCdm(CdmContext* cdm_context,
                          const CdmAttachedCB& cdm_attached_cb) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(cdm_context);

  if (cdm_context_) {
    DVLOG(1) << "Switching CDM not supported.";
    cdm_attached_cb.Run(false);
    return;
  }

  cdm_context_ = cdm_context;

  if (decryptor_ready_cb_.is_null()) {
    cdm_attached_cb.Run(true);
    return;
  }

  base::ResetAndReturn(&decryptor_ready_cb_)
      .Run(cdm_context->GetDecryptor(), cdm_attached_cb);
}

void RendererImpl::Flush(const base::Closure& flush_cb) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(flush_cb_.is_null());

  if (state_ != STATE_PLAYING) {
    DCHECK_EQ(state_, STATE_ERROR);
    return;
  }

  flush_cb_ = flush_cb;
  state_ = STATE_FLUSHING;

  if (time_ticking_)
    PausePlayback();

  FlushAudioRenderer();
}

void RendererImpl::StartPlayingFrom(base::TimeDelta time) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (state_ != STATE_PLAYING) {
    DCHECK_EQ(state_, STATE_ERROR);
    return;
  }

  time_source_->SetMediaTime(time);

  if (audio_renderer_)
    audio_renderer_->StartPlaying();
  if (video_renderer_)
    video_renderer_->StartPlayingFrom(time);
}

void RendererImpl::SetPlaybackRate(double playback_rate) {
  DVLOG(1) << __FUNCTION__ << "(" << playback_rate << ")";
  DCHECK(task_runner_->BelongsToCurrentThread());

  // Playback rate changes are only carried out while playing.
  if (state_ != STATE_PLAYING)
    return;

  time_source_->SetPlaybackRate(playback_rate);

  const double old_rate = playback_rate_;
  playback_rate_ = playback_rate;
  if (!time_ticking_ || !video_renderer_)
    return;

  if (old_rate == 0 && playback_rate > 0)
    video_renderer_->OnTimeStateChanged(true);
  else if (old_rate > 0 && playback_rate == 0)
    video_renderer_->OnTimeStateChanged(false);
}

void RendererImpl::SetVolume(float volume) {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (audio_renderer_)
    audio_renderer_->SetVolume(volume);
}

base::TimeDelta RendererImpl::GetMediaTime() {
  // No BelongsToCurrentThread() checking because this can be called from other
  // threads.
  return time_source_->CurrentMediaTime();
}

bool RendererImpl::HasAudio() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  return audio_renderer_ != NULL;
}

bool RendererImpl::HasVideo() {
  DCHECK(task_runner_->BelongsToCurrentThread());
  return video_renderer_ != NULL;
}

void RendererImpl::DisableUnderflowForTesting() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_UNINITIALIZED);

  underflow_disabled_for_testing_ = true;
}

void RendererImpl::EnableClocklessVideoPlaybackForTesting() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_UNINITIALIZED);
  DCHECK(underflow_disabled_for_testing_)
      << "Underflow must be disabled for clockless video playback";

  clockless_video_playback_enabled_for_testing_ = true;
}

bool RendererImpl::GetWallClockTimes(
    const std::vector<base::TimeDelta>& media_timestamps,
    std::vector<base::TimeTicks>* wall_clock_times) {
  // No BelongsToCurrentThread() checking because this can be called from other
  // threads.
  //
  // TODO(scherkus): Currently called from VideoRendererImpl's internal thread,
  // which should go away at some point http://crbug.com/110814
  if (clockless_video_playback_enabled_for_testing_) {
    *wall_clock_times = std::vector<base::TimeTicks>(media_timestamps.size(),
                                                     base::TimeTicks::Now());
    return true;
  }

  return time_source_->GetWallClockTimes(media_timestamps, wall_clock_times);
}

void RendererImpl::SetDecryptorReadyCallback(
    const DecryptorReadyCB& decryptor_ready_cb) {
  // Cancels the previous decryptor request.
  if (decryptor_ready_cb.is_null()) {
    if (!decryptor_ready_cb_.is_null()) {
      base::ResetAndReturn(&decryptor_ready_cb_)
          .Run(nullptr, base::Bind(IgnoreCdmAttached));
    }
    return;
  }

  // We initialize audio and video decoders in sequence.
  DCHECK(decryptor_ready_cb_.is_null());

  if (cdm_context_) {
    decryptor_ready_cb.Run(cdm_context_->GetDecryptor(),
                           base::Bind(IgnoreCdmAttached));
    return;
  }

  decryptor_ready_cb_ = decryptor_ready_cb;
}

void RendererImpl::InitializeAudioRenderer() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_INITIALIZING);
  DCHECK(!init_cb_.is_null());

  PipelineStatusCB done_cb =
      base::Bind(&RendererImpl::OnAudioRendererInitializeDone, weak_this_);

  if (!demuxer_stream_provider_->GetStream(DemuxerStream::AUDIO)) {
    audio_renderer_.reset();
    task_runner_->PostTask(FROM_HERE, base::Bind(done_cb, PIPELINE_OK));
    return;
  }

  // Note: After the initialization of a renderer, error events from it may
  // happen at any time and all future calls must guard against STATE_ERROR.
  audio_renderer_->Initialize(
      demuxer_stream_provider_->GetStream(DemuxerStream::AUDIO), done_cb,
      base::Bind(&RendererImpl::SetDecryptorReadyCallback, weak_this_),
      base::Bind(&RendererImpl::OnUpdateStatistics, weak_this_),
      base::Bind(&RendererImpl::OnBufferingStateChanged, weak_this_,
                 &audio_buffering_state_),
      base::Bind(&RendererImpl::OnAudioRendererEnded, weak_this_),
      base::Bind(&RendererImpl::OnError, weak_this_),
      waiting_for_decryption_key_cb_);
}

void RendererImpl::OnAudioRendererInitializeDone(PipelineStatus status) {
  DVLOG(1) << __FUNCTION__ << ": " << status;
  DCHECK(task_runner_->BelongsToCurrentThread());

  // OnError() may be fired at any time by the renderers, even if they thought
  // they initialized successfully (due to delayed output device setup).
  if (state_ != STATE_INITIALIZING) {
    DCHECK(init_cb_.is_null());
    audio_renderer_.reset();
    return;
  }

  if (status != PIPELINE_OK) {
    base::ResetAndReturn(&init_cb_).Run(status);
    return;
  }

  DCHECK(!init_cb_.is_null());
  InitializeVideoRenderer();
}

void RendererImpl::InitializeVideoRenderer() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_INITIALIZING);
  DCHECK(!init_cb_.is_null());

  PipelineStatusCB done_cb =
      base::Bind(&RendererImpl::OnVideoRendererInitializeDone, weak_this_);

  if (!demuxer_stream_provider_->GetStream(DemuxerStream::VIDEO)) {
    video_renderer_.reset();
    task_runner_->PostTask(FROM_HERE, base::Bind(done_cb, PIPELINE_OK));
    return;
  }

  video_renderer_->Initialize(
      demuxer_stream_provider_->GetStream(DemuxerStream::VIDEO), done_cb,
      base::Bind(&RendererImpl::SetDecryptorReadyCallback, weak_this_),
      base::Bind(&RendererImpl::OnUpdateStatistics, weak_this_),
      base::Bind(&RendererImpl::OnBufferingStateChanged, weak_this_,
                 &video_buffering_state_),
      base::Bind(&RendererImpl::OnVideoRendererEnded, weak_this_),
      base::Bind(&RendererImpl::OnError, weak_this_),
      base::Bind(&RendererImpl::GetWallClockTimes, base::Unretained(this)),
      waiting_for_decryption_key_cb_);
}

void RendererImpl::OnVideoRendererInitializeDone(PipelineStatus status) {
  DVLOG(1) << __FUNCTION__ << ": " << status;
  DCHECK(task_runner_->BelongsToCurrentThread());

  // OnError() may be fired at any time by the renderers, even if they thought
  // they initialized successfully (due to delayed output device setup).
  if (state_ != STATE_INITIALIZING) {
    DCHECK(init_cb_.is_null());
    audio_renderer_.reset();
    video_renderer_.reset();
    return;
  }

  DCHECK(!init_cb_.is_null());

  if (status != PIPELINE_OK) {
    base::ResetAndReturn(&init_cb_).Run(status);
    return;
  }

  if (audio_renderer_) {
    time_source_ = audio_renderer_->GetTimeSource();
  } else if (!time_source_) {
    wall_clock_time_source_.reset(new WallClockTimeSource());
    time_source_ = wall_clock_time_source_.get();
  }

  state_ = STATE_PLAYING;
  DCHECK(time_source_);
  DCHECK(audio_renderer_ || video_renderer_);
  base::ResetAndReturn(&init_cb_).Run(PIPELINE_OK);
}

void RendererImpl::FlushAudioRenderer() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_FLUSHING);
  DCHECK(!flush_cb_.is_null());

  if (!audio_renderer_) {
    OnAudioRendererFlushDone();
    return;
  }

  audio_renderer_->Flush(
      base::Bind(&RendererImpl::OnAudioRendererFlushDone, weak_this_));
}

void RendererImpl::OnAudioRendererFlushDone() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (state_ == STATE_ERROR) {
    DCHECK(flush_cb_.is_null());
    return;
  }

  DCHECK_EQ(state_, STATE_FLUSHING);
  DCHECK(!flush_cb_.is_null());

  // If we had a deferred video renderer underflow prior to the flush, it should
  // have been cleared by the audio renderer changing to BUFFERING_HAVE_NOTHING.
  DCHECK(deferred_underflow_cb_.IsCancelled());

  DCHECK_EQ(audio_buffering_state_, BUFFERING_HAVE_NOTHING);
  audio_ended_ = false;
  FlushVideoRenderer();
}

void RendererImpl::FlushVideoRenderer() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_FLUSHING);
  DCHECK(!flush_cb_.is_null());

  if (!video_renderer_) {
    OnVideoRendererFlushDone();
    return;
  }

  video_renderer_->Flush(
      base::Bind(&RendererImpl::OnVideoRendererFlushDone, weak_this_));
}

void RendererImpl::OnVideoRendererFlushDone() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (state_ == STATE_ERROR) {
    DCHECK(flush_cb_.is_null());
    return;
  }

  DCHECK_EQ(state_, STATE_FLUSHING);
  DCHECK(!flush_cb_.is_null());

  DCHECK_EQ(video_buffering_state_, BUFFERING_HAVE_NOTHING);
  video_ended_ = false;
  state_ = STATE_PLAYING;
  base::ResetAndReturn(&flush_cb_).Run();
}

void RendererImpl::OnUpdateStatistics(const PipelineStatistics& stats) {
  DCHECK(task_runner_->BelongsToCurrentThread());
  statistics_cb_.Run(stats);
}

void RendererImpl::OnBufferingStateChanged(BufferingState* buffering_state,
                                           BufferingState new_buffering_state) {
  const bool is_audio = buffering_state == &audio_buffering_state_;
  DVLOG(1) << __FUNCTION__ << "(" << *buffering_state << ", "
           << new_buffering_state << ") " << (is_audio ? "audio" : "video");
  DCHECK(task_runner_->BelongsToCurrentThread());

  bool was_waiting_for_enough_data = WaitingForEnoughData();

  // When audio is present and has enough data, defer video underflow callbacks
  // for some time to avoid unnecessary glitches in audio; see
  // http://crbug.com/144683#c53.
  if (audio_renderer_ && !is_audio && state_ == STATE_PLAYING) {
    if (video_buffering_state_ == BUFFERING_HAVE_ENOUGH &&
        audio_buffering_state_ == BUFFERING_HAVE_ENOUGH &&
        new_buffering_state == BUFFERING_HAVE_NOTHING &&
        deferred_underflow_cb_.IsCancelled()) {
      deferred_underflow_cb_.Reset(base::Bind(
          &RendererImpl::OnBufferingStateChanged, weak_factory_.GetWeakPtr(),
          buffering_state, new_buffering_state));
      task_runner_->PostDelayedTask(FROM_HERE,
                                    deferred_underflow_cb_.callback(),
                                    video_underflow_threshold_);
      return;
    }

    deferred_underflow_cb_.Cancel();
  } else if (!deferred_underflow_cb_.IsCancelled() && is_audio &&
             new_buffering_state == BUFFERING_HAVE_NOTHING) {
    // If audio underflows while we have a deferred video underflow in progress
    // we want to mark video as underflowed immediately and cancel the deferral.
    deferred_underflow_cb_.Cancel();
    video_buffering_state_ = BUFFERING_HAVE_NOTHING;
  }

  *buffering_state = new_buffering_state;

  // Disable underflow by ignoring updates that renderers have ran out of data.
  if (state_ == STATE_PLAYING && underflow_disabled_for_testing_ &&
      time_ticking_) {
    DVLOG(1) << "Update ignored because underflow is disabled for testing.";
    return;
  }

  // Renderer underflowed.
  if (!was_waiting_for_enough_data && WaitingForEnoughData()) {
    PausePlayback();

    // TODO(scherkus): Fire BUFFERING_HAVE_NOTHING callback to alert clients of
    // underflow state http://crbug.com/144683
    return;
  }

  // Renderer prerolled.
  if (was_waiting_for_enough_data && !WaitingForEnoughData()) {
    StartPlayback();
    buffering_state_cb_.Run(BUFFERING_HAVE_ENOUGH);
    return;
  }
}

bool RendererImpl::WaitingForEnoughData() const {
  DCHECK(task_runner_->BelongsToCurrentThread());
  if (state_ != STATE_PLAYING)
    return false;
  if (audio_renderer_ && audio_buffering_state_ != BUFFERING_HAVE_ENOUGH)
    return true;
  if (video_renderer_ && video_buffering_state_ != BUFFERING_HAVE_ENOUGH)
    return true;
  return false;
}

void RendererImpl::PausePlayback() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK(time_ticking_);
  switch (state_) {
    case STATE_PLAYING:
      DCHECK(PlaybackHasEnded() || WaitingForEnoughData())
          << "Playback should only pause due to ending or underflowing";
      break;

    case STATE_FLUSHING:
      // It's OK to pause playback when flushing.
      break;

    case STATE_UNINITIALIZED:
    case STATE_INITIALIZING:
      NOTREACHED() << "Invalid state: " << state_;
      break;

    case STATE_ERROR:
      // An error state may occur at any time.
      break;
  }

  time_ticking_ = false;
  time_source_->StopTicking();
  if (playback_rate_ > 0 && video_renderer_)
    video_renderer_->OnTimeStateChanged(false);
}

void RendererImpl::StartPlayback() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_EQ(state_, STATE_PLAYING);
  DCHECK(!time_ticking_);
  DCHECK(!WaitingForEnoughData());

  time_ticking_ = true;
  time_source_->StartTicking();
  if (playback_rate_ > 0 && video_renderer_)
    video_renderer_->OnTimeStateChanged(true);
}

void RendererImpl::OnAudioRendererEnded() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (state_ != STATE_PLAYING)
    return;

  DCHECK(!audio_ended_);
  audio_ended_ = true;

  RunEndedCallbackIfNeeded();
}

void RendererImpl::OnVideoRendererEnded() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (state_ != STATE_PLAYING)
    return;

  DCHECK(!video_ended_);
  video_ended_ = true;

  RunEndedCallbackIfNeeded();
}

bool RendererImpl::PlaybackHasEnded() const {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (audio_renderer_ && !audio_ended_)
    return false;

  if (video_renderer_ && !video_ended_)
    return false;

  return true;
}

void RendererImpl::RunEndedCallbackIfNeeded() {
  DVLOG(1) << __FUNCTION__;
  DCHECK(task_runner_->BelongsToCurrentThread());

  if (!PlaybackHasEnded())
    return;

  if (time_ticking_)
    PausePlayback();

  ended_cb_.Run();
}

void RendererImpl::OnError(PipelineStatus error) {
  DVLOG(1) << __FUNCTION__ << "(" << error << ")";
  DCHECK(task_runner_->BelongsToCurrentThread());
  DCHECK_NE(PIPELINE_OK, error) << "PIPELINE_OK isn't an error!";

  // An error has already been delivered.
  if (state_ == STATE_ERROR)
    return;

  const State old_state = state_;
  state_ = STATE_ERROR;

  if (old_state == STATE_INITIALIZING) {
    base::ResetAndReturn(&init_cb_).Run(error);
    return;
  }

  // After OnError() returns, the pipeline may destroy |this|.
  base::ResetAndReturn(&error_cb_).Run(error);

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

}  // namespace media