media/base/audio_renderer_mixer_input.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_input.h"
   6
   7 #include "base/bind.h"
   8 #include "base/logging.h"
   9 #include "media/base/audio_renderer_mixer.h"
  10
  11 namespace media {
  12
  13 AudioRendererMixerInput::AudioRendererMixerInput(
  14     const GetMixerCB& get_mixer_cb, const RemoveMixerCB& remove_mixer_cb)
  15     : playing_(false),
  16       initialized_(false),
  17       volume_(1.0f),
  18       get_mixer_cb_(get_mixer_cb),
  19       remove_mixer_cb_(remove_mixer_cb),
  20       mixer_(NULL),
  21       callback_(NULL),
  22       error_cb_(base::Bind(
  23           &AudioRendererMixerInput::OnRenderError, base::Unretained(this))) {
  24 }
  25
  26 AudioRendererMixerInput::~AudioRendererMixerInput() {
  27   DCHECK(!playing_);
  28   DCHECK(!mixer_);
  29 }
  30
  31 void AudioRendererMixerInput::Initialize(
  32     const AudioParameters& params,
  33     AudioRendererSink::RenderCallback* callback) {
  34   DCHECK(callback);
  35   DCHECK(!initialized_);
  36
  37   params_ = params;
  38   callback_ = callback;
  39   initialized_ = true;
  40 }
  41
  42 void AudioRendererMixerInput::Start() {
  43   DCHECK(initialized_);
  44   DCHECK(!playing_);
  45   DCHECK(!mixer_);
  46   mixer_ = get_mixer_cb_.Run(params_);
  47
  48   // Note: OnRenderError() may be called immediately after this call returns.
  49   mixer_->AddErrorCallback(error_cb_);
  50 }
  51
  52 void AudioRendererMixerInput::Stop() {
  53   // Stop() may be called at any time, if Pause() hasn't been called we need to
  54   // remove our mixer input before shutdown.
  55   if (playing_) {
  56     mixer_->RemoveMixerInput(this);
  57     playing_ = false;
  58   }
  59
  60   if (mixer_) {
  61     // TODO(dalecurtis): This is required so that |callback_| isn't called after
  62     // Stop() by an error event since it may outlive this ref-counted object. We
  63     // should instead have sane ownership semantics: http://crbug.com/151051
  64     mixer_->RemoveErrorCallback(error_cb_);
  65     remove_mixer_cb_.Run(params_);
  66     mixer_ = NULL;
  67   }
  68 }
  69
  70 void AudioRendererMixerInput::Play() {
  71   DCHECK(initialized_);
  72   DCHECK(mixer_);
  73
  74   if (playing_)
  75     return;
  76
  77   mixer_->AddMixerInput(this);
  78   playing_ = true;
  79 }
  80
  81 void AudioRendererMixerInput::Pause() {
  82   DCHECK(initialized_);
  83   DCHECK(mixer_);
  84
  85   if (!playing_)
  86     return;
  87
  88   mixer_->RemoveMixerInput(this);
  89   playing_ = false;
  90 }
  91
  92 bool AudioRendererMixerInput::SetVolume(double volume) {
  93   volume_ = volume;
  94   return true;
  95 }
  96
  97 double AudioRendererMixerInput::ProvideInput(AudioBus* audio_bus,
  98                                              base::TimeDelta buffer_delay) {
  99   int frames_filled = callback_->Render(
 100       audio_bus, static_cast<int>(buffer_delay.InMillisecondsF() + 0.5));
 101
 102   // AudioConverter expects unfilled frames to be zeroed.
 103   if (frames_filled < audio_bus->frames()) {
 104     audio_bus->ZeroFramesPartial(
 105         frames_filled, audio_bus->frames() - frames_filled);
 106   }
 107
 108   return frames_filled > 0 ? volume_ : 0;
 109 }
 110
 111 void AudioRendererMixerInput::OnRenderError() {
 112   callback_->OnRenderError();
 113 }
 114
 115 }  // namespace media