virtual_audio_output_stream.cc revision 868fa2fe829687343ffae624259930155e16dbd8 
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/message_loop/message_loop_proxy.h"
8#include "media/audio/virtual_audio_input_stream.h"
9
10namespace media {
11
12VirtualAudioOutputStream::VirtualAudioOutputStream(
13    const AudioParameters& params, base::MessageLoopProxy* message_loop,
14    VirtualAudioInputStream* target, const AfterCloseCallback& after_close_cb)
15    : params_(params), message_loop_(message_loop),
16      target_input_stream_(target), after_close_cb_(after_close_cb),
17      callback_(NULL), volume_(1.0f) {
18  DCHECK(params_.IsValid());
19  DCHECK(message_loop_);
20  DCHECK(target);
21}
22
23VirtualAudioOutputStream::~VirtualAudioOutputStream() {
24  DCHECK(!callback_);
25}
26
27bool VirtualAudioOutputStream::Open() {
28  DCHECK(message_loop_->BelongsToCurrentThread());
29  return true;
30}
31
32void VirtualAudioOutputStream::Start(AudioSourceCallback* callback)  {
33  DCHECK(message_loop_->BelongsToCurrentThread());
34  DCHECK(!callback_);
35  callback_ = callback;
36  target_input_stream_->AddOutputStream(this, params_);
37}
38
39void VirtualAudioOutputStream::Stop() {
40  DCHECK(message_loop_->BelongsToCurrentThread());
41  if (callback_) {
42    callback_ = NULL;
43    target_input_stream_->RemoveOutputStream(this, params_);
44  }
45}
46
47void VirtualAudioOutputStream::Close() {
48  DCHECK(message_loop_->BelongsToCurrentThread());
49
50  Stop();
51
52  // If a non-null AfterCloseCallback was provided to the constructor, invoke it
53  // here.  The callback is moved to a stack-local first since |this| could be
54  // destroyed during Run().
55  if (!after_close_cb_.is_null()) {
56    const AfterCloseCallback cb = after_close_cb_;
57    after_close_cb_.Reset();
58    cb.Run(this);
59  }
60}
61
62void VirtualAudioOutputStream::SetVolume(double volume) {
63  DCHECK(message_loop_->BelongsToCurrentThread());
64  volume_ = volume;
65}
66
67void VirtualAudioOutputStream::GetVolume(double* volume) {
68  DCHECK(message_loop_->BelongsToCurrentThread());
69  *volume = volume_;
70}
71
72double VirtualAudioOutputStream::ProvideInput(AudioBus* audio_bus,
73                                              base::TimeDelta buffer_delay) {
74  DCHECK(message_loop_->BelongsToCurrentThread());
75  DCHECK(callback_);
76
77  const int frames = callback_->OnMoreData(audio_bus, AudioBuffersState());
78  if (frames < audio_bus->frames())
79    audio_bus->ZeroFramesPartial(frames, audio_bus->frames() - frames);
80
81  return frames > 0 ? volume_ : 0;
82}
83
84}  // namespace media
85