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::TimeTicks::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   // Ensure that all mixer inputs have removed themselves prior to destruction.
  33   DCHECK(audio_converter_.empty());
  34   DCHECK_EQ(error_callbacks_.size(), 0U);
  35 }
  36
  37 void AudioRendererMixer::AddMixerInput(AudioConverter::InputCallback* input) {
  38   base::AutoLock auto_lock(lock_);
  39   if (!playing_) {
  40     playing_ = true;
  41     last_play_time_ = base::TimeTicks::Now();
  42     audio_sink_->Play();
  43   }
  44
  45   audio_converter_.AddInput(input);
  46 }
  47
  48 void AudioRendererMixer::RemoveMixerInput(
  49     AudioConverter::InputCallback* input) {
  50   base::AutoLock auto_lock(lock_);
  51   audio_converter_.RemoveInput(input);
  52 }
  53
  54 void AudioRendererMixer::AddErrorCallback(const base::Closure& error_cb) {
  55   base::AutoLock auto_lock(lock_);
  56   error_callbacks_.push_back(error_cb);
  57 }
  58
  59 void AudioRendererMixer::RemoveErrorCallback(const base::Closure& error_cb) {
  60   base::AutoLock auto_lock(lock_);
  61   for (ErrorCallbackList::iterator it = error_callbacks_.begin();
  62        it != error_callbacks_.end();
  63        ++it) {
  64     if (it->Equals(error_cb)) {
  65       error_callbacks_.erase(it);
  66       return;
  67     }
  68   }
  69
  70   // An error callback should always exist when called.
  71   NOTREACHED();
  72 }
  73
  74 int AudioRendererMixer::Render(AudioBus* audio_bus,
  75                                int audio_delay_milliseconds) {
  76   base::AutoLock auto_lock(lock_);
  77
  78   // If there are no mixer inputs and we haven't seen one for a while, pause the
  79   // sink to avoid wasting resources when media elements are present but remain
  80   // in the pause state.
  81   const base::TimeTicks now = base::TimeTicks::Now();
  82   if (!audio_converter_.empty()) {
  83     last_play_time_ = now;
  84   } else if (now - last_play_time_ >= pause_delay_ && playing_) {
  85     audio_sink_->Pause();
  86     playing_ = false;
  87   }
  88
  89   audio_converter_.ConvertWithDelay(
  90       base::TimeDelta::FromMilliseconds(audio_delay_milliseconds), audio_bus);
  91   return audio_bus->frames();
  92 }
  93
  94 void AudioRendererMixer::OnRenderError() {
  95   // Call each mixer input and signal an error.
  96   base::AutoLock auto_lock(lock_);
  97   for (const auto& cb : error_callbacks_)
  98     cb.Run();
  99 }
 100
 101 }  // namespace media