media/audio/virtual_audio_input_stream.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/audio/virtual_audio_input_stream.h"
   6
   7 #include <algorithm>
   8 #include <utility>
   9
  10 #include "base/bind.h"
  11 #include "base/single_thread_task_runner.h"
  12 #include "media/audio/virtual_audio_output_stream.h"
  13
  14 namespace media {
  15
  16 // LoopbackAudioConverter works similar to AudioConverter and converts input
  17 // streams to different audio parameters. Then, the LoopbackAudioConverter can
  18 // be used as an input to another AudioConverter. This allows us to
  19 // use converted audio from AudioOutputStreams as input to an AudioConverter.
  20 // For example, this allows converting multiple streams into a common format and
  21 // using the converted audio as input to another AudioConverter (i.e. a mixer).
  22 class LoopbackAudioConverter : public AudioConverter::InputCallback {
  23  public:
  24   LoopbackAudioConverter(const AudioParameters& input_params,
  25                          const AudioParameters& output_params)
  26       : audio_converter_(input_params, output_params, false) {}
  27
  28   ~LoopbackAudioConverter() override {}
  29
  30   void AddInput(AudioConverter::InputCallback* input) {
  31     audio_converter_.AddInput(input);
  32   }
  33
  34   void RemoveInput(AudioConverter::InputCallback* input) {
  35     audio_converter_.RemoveInput(input);
  36   }
  37
  38  private:
  39   double ProvideInput(AudioBus* audio_bus,
  40                       base::TimeDelta buffer_delay) override {
  41     audio_converter_.ConvertWithDelay(buffer_delay, audio_bus);
  42     return 1.0;
  43   }
  44
  45   AudioConverter audio_converter_;
  46
  47   DISALLOW_COPY_AND_ASSIGN(LoopbackAudioConverter);
  48 };
  49
  50 VirtualAudioInputStream::VirtualAudioInputStream(
  51     const AudioParameters& params,
  52     const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
  53     const AfterCloseCallback& after_close_cb)
  54     : worker_task_runner_(worker_task_runner),
  55       after_close_cb_(after_close_cb),
  56       callback_(NULL),
  57       buffer_(new uint8[params.GetBytesPerBuffer()]),
  58       params_(params),
  59       mixer_(params_, params_, false),
  60       num_attached_output_streams_(0),
  61       fake_consumer_(worker_task_runner_, params_) {
  62   DCHECK(params_.IsValid());
  63   DCHECK(worker_task_runner_.get());
  64
  65   // VAIS can be constructed on any thread, but will DCHECK that all
  66   // AudioInputStream methods are called from the same thread.
  67   thread_checker_.DetachFromThread();
  68 }
  69
  70 VirtualAudioInputStream::~VirtualAudioInputStream() {
  71   DCHECK(!callback_);
  72
  73   // Sanity-check: Contract for Add/RemoveOutputStream() requires that all
  74   // output streams be removed before VirtualAudioInputStream is destroyed.
  75   DCHECK_EQ(0, num_attached_output_streams_);
  76
  77   for (AudioConvertersMap::iterator it = converters_.begin();
  78        it != converters_.end(); ++it) {
  79     delete it->second;
  80   }
  81 }
  82
  83 bool VirtualAudioInputStream::Open() {
  84   DCHECK(thread_checker_.CalledOnValidThread());
  85   memset(buffer_.get(), 0, params_.GetBytesPerBuffer());
  86   return true;
  87 }
  88
  89 void VirtualAudioInputStream::Start(AudioInputCallback* callback) {
  90   DCHECK(thread_checker_.CalledOnValidThread());
  91   callback_ = callback;
  92   fake_consumer_.Start(base::Bind(
  93       &VirtualAudioInputStream::PumpAudio, base::Unretained(this)));
  94 }
  95
  96 void VirtualAudioInputStream::Stop() {
  97   DCHECK(thread_checker_.CalledOnValidThread());
  98   fake_consumer_.Stop();
  99   callback_ = NULL;
 100 }
 101
 102 void VirtualAudioInputStream::AddOutputStream(
 103     VirtualAudioOutputStream* stream, const AudioParameters& output_params) {
 104   DCHECK(thread_checker_.CalledOnValidThread());
 105
 106   base::AutoLock scoped_lock(converter_network_lock_);
 107
 108   AudioConvertersMap::iterator converter = converters_.find(output_params);
 109   if (converter == converters_.end()) {
 110     std::pair<AudioConvertersMap::iterator, bool> result = converters_.insert(
 111         std::make_pair(output_params,
 112                        new LoopbackAudioConverter(output_params, params_)));
 113     converter = result.first;
 114
 115     // Add to main mixer if we just added a new AudioTransform.
 116     mixer_.AddInput(converter->second);
 117   }
 118   converter->second->AddInput(stream);
 119   ++num_attached_output_streams_;
 120 }
 121
 122 void VirtualAudioInputStream::RemoveOutputStream(
 123     VirtualAudioOutputStream* stream, const AudioParameters& output_params) {
 124   DCHECK(thread_checker_.CalledOnValidThread());
 125
 126   base::AutoLock scoped_lock(converter_network_lock_);
 127
 128   DCHECK(converters_.find(output_params) != converters_.end());
 129   converters_[output_params]->RemoveInput(stream);
 130
 131   --num_attached_output_streams_;
 132   DCHECK_LE(0, num_attached_output_streams_);
 133 }
 134
 135 void VirtualAudioInputStream::PumpAudio(AudioBus* audio_bus) {
 136   DCHECK(worker_task_runner_->BelongsToCurrentThread());
 137
 138   {
 139     base::AutoLock scoped_lock(converter_network_lock_);
 140     // Because the audio is being looped-back, the delay until it will be played
 141     // out is zero.
 142     mixer_.ConvertWithDelay(base::TimeDelta(), audio_bus);
 143   }
 144   // Because the audio is being looped-back, the delay since since it was
 145   // recorded is zero.
 146   callback_->OnData(this, audio_bus, 0, 1.0);
 147 }
 148
 149 void VirtualAudioInputStream::Close() {
 150   DCHECK(thread_checker_.CalledOnValidThread());
 151
 152   Stop();  // Make sure callback_ is no longer being used.
 153
 154   // If a non-null AfterCloseCallback was provided to the constructor, invoke it
 155   // here.  The callback is moved to a stack-local first since |this| could be
 156   // destroyed during Run().
 157   if (!after_close_cb_.is_null()) {
 158     const AfterCloseCallback cb = after_close_cb_;
 159     after_close_cb_.Reset();
 160     cb.Run(this);
 161   }
 162 }
 163
 164 double VirtualAudioInputStream::GetMaxVolume() {
 165   return 1.0;
 166 }
 167
 168 void VirtualAudioInputStream::SetVolume(double volume) {}
 169
 170 double VirtualAudioInputStream::GetVolume() {
 171   return 1.0;
 172 }
 173
 174 bool VirtualAudioInputStream::SetAutomaticGainControl(bool enabled) {
 175   return false;
 176 }
 177
 178 bool VirtualAudioInputStream::GetAutomaticGainControl() {
 179   return false;
 180 }
 181
 182 bool VirtualAudioInputStream::IsMuted() {
 183   return false;
 184 }
 185
 186 }  // namespace media