media/base/audio_renderer_mixer.cc

   1 // Copyright (c) 2012 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 #include "media/base/audio_renderer_mixer.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/logging.h"
  10
  11 namespace media {
  12
  13 enum { kPauseDelaySeconds = 10 };
  14
  15 AudioRendererMixer::AudioRendererMixer(
  16     const AudioParameters& input_params, const AudioParameters& output_params,
  17     const scoped_refptr<AudioRendererSink>& sink)
  18     : audio_sink_(sink),
  19       audio_converter_(input_params, output_params, true),
  20       pause_delay_(base::TimeDelta::FromSeconds(kPauseDelaySeconds)),
  21       last_play_time_(base::Time::Now()),
  22       // Initialize |playing_| to true since Start() results in an auto-play.
  23       playing_(true) {
  24   audio_sink_->Initialize(output_params, this);
  25   audio_sink_->Start();
  26 }
  27
  28 AudioRendererMixer::~AudioRendererMixer() {
  29   // AudioRendererSinks must be stopped before being destructed.
  30   audio_sink_->Stop();
  31
  32   // Ensures that all mixer inputs have stopped themselves prior to destruction
  33   // and have called RemoveMixerInput().
  34   DCHECK_EQ(mixer_inputs_.size(), 0U);
  35 }
  36
  37 void AudioRendererMixer::AddMixerInput(AudioConverter::InputCallback* input,
  38                                        const base::Closure& error_cb) {
  39   base::AutoLock auto_lock(mixer_inputs_lock_);
  40
  41   if (!playing_) {
  42     playing_ = true;
  43     last_play_time_ = base::Time::Now();
  44     audio_sink_->Play();
  45   }
  46
  47   DCHECK(mixer_inputs_.find(input) == mixer_inputs_.end());
  48   mixer_inputs_[input] = error_cb;
  49   audio_converter_.AddInput(input);
  50 }
  51
  52 void AudioRendererMixer::RemoveMixerInput(
  53     AudioConverter::InputCallback* input) {
  54   base::AutoLock auto_lock(mixer_inputs_lock_);
  55   audio_converter_.RemoveInput(input);
  56
  57   DCHECK(mixer_inputs_.find(input) != mixer_inputs_.end());
  58   mixer_inputs_.erase(input);
  59 }
  60
  61 int AudioRendererMixer::Render(AudioBus* audio_bus,
  62                                int audio_delay_milliseconds) {
  63   base::AutoLock auto_lock(mixer_inputs_lock_);
  64
  65   // If there are no mixer inputs and we haven't seen one for a while, pause the
  66   // sink to avoid wasting resources when media elements are present but remain
  67   // in the pause state.
  68   base::Time now = base::Time::Now();
  69   if (!mixer_inputs_.empty()) {
  70     last_play_time_ = now;
  71   } else if (now - last_play_time_ >= pause_delay_ && playing_) {
  72     audio_sink_->Pause();
  73     playing_ = false;
  74   }
  75
  76   audio_converter_.ConvertWithDelay(
  77       base::TimeDelta::FromMilliseconds(audio_delay_milliseconds), audio_bus);
  78   return audio_bus->frames();
  79 }
  80
  81 void AudioRendererMixer::OnRenderError() {
  82   base::AutoLock auto_lock(mixer_inputs_lock_);
  83
  84   // Call each mixer input and signal an error.
  85   for (AudioRendererMixerInputSet::iterator it = mixer_inputs_.begin();
  86        it != mixer_inputs_.end(); ++it) {
  87     it->second.Run();
  88   }
  89 }
  90
  91 }  // namespace media