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/fake_audio_input_stream.h"
6
7#include "base/bind.h"
8#include "base/lazy_instance.h"
9#include "media/audio/audio_manager_base.h"
10#include "media/base/audio_bus.h"
11
12using base::TimeTicks;
13using base::TimeDelta;
14
15namespace media {
16
17namespace {
18
19// These values are based on experiments for local-to-local
20// PeerConnection to demonstrate audio/video synchronization.
21const int kBeepDurationMilliseconds = 20;
22const int kBeepFrequency = 400;
23
24// Intervals between two automatic beeps.
25const int kAutomaticBeepIntervalInMs = 500;
26
27// Automatic beep will be triggered every |kAutomaticBeepIntervalInMs| unless
28// users explicitly call BeepOnce(), which will disable the automatic beep.
29class BeepContext {
30 public:
31  BeepContext() : beep_once_(false), automatic_beep_(true) {}
32
33  void SetBeepOnce(bool enable) {
34    base::AutoLock auto_lock(lock_);
35    beep_once_ = enable;
36
37    // Disable the automatic beep if users explicit set |beep_once_| to true.
38    if (enable)
39      automatic_beep_ = false;
40  }
41  bool beep_once() const {
42    base::AutoLock auto_lock(lock_);
43    return beep_once_;
44  }
45  bool automatic_beep() const {
46    base::AutoLock auto_lock(lock_);
47    return automatic_beep_;
48  }
49
50 private:
51  mutable base::Lock lock_;
52  bool beep_once_;
53  bool automatic_beep_;
54};
55
56static base::LazyInstance<BeepContext> g_beep_context =
57    LAZY_INSTANCE_INITIALIZER;
58
59}  // namespace
60
61AudioInputStream* FakeAudioInputStream::MakeFakeStream(
62    AudioManagerBase* manager,
63    const AudioParameters& params) {
64  return new FakeAudioInputStream(manager, params);
65}
66
67FakeAudioInputStream::FakeAudioInputStream(AudioManagerBase* manager,
68                                           const AudioParameters& params)
69    : audio_manager_(manager),
70      callback_(NULL),
71      buffer_size_((params.channels() * params.bits_per_sample() *
72                    params.frames_per_buffer()) /
73                   8),
74      params_(params),
75      task_runner_(manager->GetTaskRunner()),
76      callback_interval_(base::TimeDelta::FromMilliseconds(
77          (params.frames_per_buffer() * 1000) / params.sample_rate())),
78      beep_duration_in_buffers_(kBeepDurationMilliseconds *
79                                params.sample_rate() /
80                                params.frames_per_buffer() /
81                                1000),
82      beep_generated_in_buffers_(0),
83      beep_period_in_frames_(params.sample_rate() / kBeepFrequency),
84      frames_elapsed_(0),
85      audio_bus_(AudioBus::Create(params)),
86      weak_factory_(this) {
87  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
88}
89
90FakeAudioInputStream::~FakeAudioInputStream() {}
91
92bool FakeAudioInputStream::Open() {
93  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
94  buffer_.reset(new uint8[buffer_size_]);
95  memset(buffer_.get(), 0, buffer_size_);
96  audio_bus_->Zero();
97  return true;
98}
99
100void FakeAudioInputStream::Start(AudioInputCallback* callback)  {
101  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
102  DCHECK(!callback_);
103  callback_ = callback;
104  last_callback_time_ = TimeTicks::Now();
105  task_runner_->PostDelayedTask(
106      FROM_HERE,
107      base::Bind(&FakeAudioInputStream::DoCallback, weak_factory_.GetWeakPtr()),
108      callback_interval_);
109}
110
111void FakeAudioInputStream::DoCallback() {
112  DCHECK(callback_);
113
114  const TimeTicks now = TimeTicks::Now();
115  base::TimeDelta next_callback_time =
116      last_callback_time_ + callback_interval_ * 2 - now;
117
118  // If we are falling behind, try to catch up as much as we can in the next
119  // callback.
120  if (next_callback_time < base::TimeDelta())
121    next_callback_time = base::TimeDelta();
122
123  // Accumulate the time from the last beep.
124  interval_from_last_beep_ += now - last_callback_time_;
125
126  last_callback_time_ = now;
127
128  memset(buffer_.get(), 0, buffer_size_);
129
130  bool should_beep = false;
131  {
132    BeepContext* beep_context = g_beep_context.Pointer();
133    if (beep_context->automatic_beep()) {
134      base::TimeDelta delta = interval_from_last_beep_ -
135          TimeDelta::FromMilliseconds(kAutomaticBeepIntervalInMs);
136      if (delta > base::TimeDelta()) {
137        should_beep = true;
138        interval_from_last_beep_ = delta;
139      }
140    } else {
141      should_beep = beep_context->beep_once();
142      beep_context->SetBeepOnce(false);
143    }
144  }
145
146  // If this object was instructed to generate a beep or has started to
147  // generate a beep sound.
148  if (should_beep || beep_generated_in_buffers_) {
149    // Compute the number of frames to output high value. Then compute the
150    // number of bytes based on channels and bits per channel.
151    int high_frames = beep_period_in_frames_ / 2;
152    int high_bytes = high_frames * params_.bits_per_sample() *
153        params_.channels() / 8;
154
155    // Separate high and low with the same number of bytes to generate a
156    // square wave.
157    int position = 0;
158    while (position + high_bytes <= buffer_size_) {
159      // Write high values first.
160      memset(buffer_.get() + position, 128, high_bytes);
161      // Then leave low values in the buffer with |high_bytes|.
162      position += high_bytes * 2;
163    }
164
165    ++beep_generated_in_buffers_;
166    if (beep_generated_in_buffers_ >= beep_duration_in_buffers_)
167      beep_generated_in_buffers_ = 0;
168  }
169
170  audio_bus_->FromInterleaved(
171      buffer_.get(), audio_bus_->frames(), params_.bits_per_sample() / 8);
172  callback_->OnData(this, audio_bus_.get(), buffer_size_, 1.0);
173  frames_elapsed_ += params_.frames_per_buffer();
174
175  task_runner_->PostDelayedTask(
176      FROM_HERE,
177      base::Bind(&FakeAudioInputStream::DoCallback, weak_factory_.GetWeakPtr()),
178      next_callback_time);
179}
180
181void FakeAudioInputStream::Stop() {
182  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
183  weak_factory_.InvalidateWeakPtrs();
184  callback_ = NULL;
185}
186
187void FakeAudioInputStream::Close() {
188  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
189  audio_manager_->ReleaseInputStream(this);
190}
191
192double FakeAudioInputStream::GetMaxVolume() {
193  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
194  return 1.0;
195}
196
197void FakeAudioInputStream::SetVolume(double volume) {
198  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
199}
200
201double FakeAudioInputStream::GetVolume() {
202  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
203  return 1.0;
204}
205
206bool FakeAudioInputStream::IsMuted() {
207  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
208  return false;
209}
210
211void FakeAudioInputStream::SetAutomaticGainControl(bool enabled) {}
212
213bool FakeAudioInputStream::GetAutomaticGainControl() {
214  return true;
215}
216
217// static
218void FakeAudioInputStream::BeepOnce() {
219  BeepContext* beep_context = g_beep_context.Pointer();
220  beep_context->SetBeepOnce(true);
221}
222
223}  // namespace media
224