media/audio/virtual_audio_output_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_output_stream.h"
   6
   7 #include "base/logging.h"
   8 #include "media/audio/virtual_audio_input_stream.h"
   9
  10 namespace media {
  11
  12 VirtualAudioOutputStream::VirtualAudioOutputStream(
  13     const AudioParameters& params, VirtualAudioInputStream* target,
  14     const AfterCloseCallback& after_close_cb)
  15     : params_(params), target_input_stream_(target),
  16       after_close_cb_(after_close_cb), callback_(NULL), volume_(1.0f) {
  17   DCHECK(params_.IsValid());
  18   DCHECK(target);
  19
  20   // VAOS can be constructed on any thread, but will DCHECK that all
  21   // AudioOutputStream methods are called from the same thread.
  22   thread_checker_.DetachFromThread();
  23 }
  24
  25 VirtualAudioOutputStream::~VirtualAudioOutputStream() {
  26   DCHECK(!callback_);
  27 }
  28
  29 bool VirtualAudioOutputStream::Open() {
  30   DCHECK(thread_checker_.CalledOnValidThread());
  31   return true;
  32 }
  33
  34 void VirtualAudioOutputStream::Start(AudioSourceCallback* callback)  {
  35   DCHECK(thread_checker_.CalledOnValidThread());
  36   DCHECK(!callback_);
  37   callback_ = callback;
  38   target_input_stream_->AddOutputStream(this, params_);
  39 }
  40
  41 void VirtualAudioOutputStream::Stop() {
  42   DCHECK(thread_checker_.CalledOnValidThread());
  43   if (callback_) {
  44     target_input_stream_->RemoveOutputStream(this, params_);
  45     callback_ = NULL;
  46   }
  47 }
  48
  49 void VirtualAudioOutputStream::Close() {
  50   DCHECK(thread_checker_.CalledOnValidThread());
  51
  52   Stop();
  53
  54   // If a non-null AfterCloseCallback was provided to the constructor, invoke it
  55   // here.  The callback is moved to a stack-local first since |this| could be
  56   // destroyed during Run().
  57   if (!after_close_cb_.is_null()) {
  58     const AfterCloseCallback cb = after_close_cb_;
  59     after_close_cb_.Reset();
  60     cb.Run(this);
  61   }
  62 }
  63
  64 void VirtualAudioOutputStream::SetVolume(double volume) {
  65   DCHECK(thread_checker_.CalledOnValidThread());
  66   volume_ = volume;
  67 }
  68
  69 void VirtualAudioOutputStream::GetVolume(double* volume) {
  70   DCHECK(thread_checker_.CalledOnValidThread());
  71   *volume = volume_;
  72 }
  73
  74 double VirtualAudioOutputStream::ProvideInput(AudioBus* audio_bus,
  75                                               base::TimeDelta buffer_delay) {
  76   // Note: This method may be invoked on any one thread, depending on the
  77   // platform.
  78   DCHECK(callback_);
  79
  80   const int frames = callback_->OnMoreData(audio_bus, AudioBuffersState());
  81   if (frames < audio_bus->frames())
  82     audio_bus->ZeroFramesPartial(frames, audio_bus->frames() - frames);
  83
  84   return frames > 0 ? volume_ : 0;
  85 }
  86
  87 }  // namespace media