null_audio_sink.cc revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d 
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/null_audio_sink.h"
6
7#include "base/bind.h"
8#include "base/message_loop_proxy.h"
9#include "media/audio/fake_audio_consumer.h"
10#include "media/base/audio_hash.h"
11
12namespace media {
13
14NullAudioSink::NullAudioSink(
15    const scoped_refptr<base::MessageLoopProxy>& message_loop)
16    : initialized_(false),
17      playing_(false),
18      callback_(NULL),
19      message_loop_(message_loop) {
20}
21
22NullAudioSink::~NullAudioSink() {}
23
24void NullAudioSink::Initialize(const AudioParameters& params,
25                               RenderCallback* callback) {
26  DCHECK(!initialized_);
27  fake_consumer_.reset(new FakeAudioConsumer(message_loop_, params));
28  callback_ = callback;
29  initialized_ = true;
30}
31
32void NullAudioSink::Start() {
33  DCHECK(message_loop_->BelongsToCurrentThread());
34  DCHECK(!playing_);
35}
36
37void NullAudioSink::Stop() {
38  DCHECK(message_loop_->BelongsToCurrentThread());
39
40  // Stop may be called at any time, so we have to check before stopping.
41  if (fake_consumer_)
42    fake_consumer_->Stop();
43}
44
45void NullAudioSink::Play() {
46  DCHECK(message_loop_->BelongsToCurrentThread());
47  DCHECK(initialized_);
48
49  if (playing_)
50    return;
51
52  fake_consumer_->Start(base::Bind(
53      &NullAudioSink::CallRender, base::Unretained(this)));
54  playing_ = true;
55}
56
57void NullAudioSink::Pause() {
58  DCHECK(message_loop_->BelongsToCurrentThread());
59
60  if (!playing_)
61    return;
62
63  fake_consumer_->Stop();
64  playing_ = false;
65}
66
67bool NullAudioSink::SetVolume(double volume) {
68  // Audio is always muted.
69  return volume == 0.0;
70}
71
72void NullAudioSink::CallRender(AudioBus* audio_bus) {
73  DCHECK(message_loop_->BelongsToCurrentThread());
74
75  int frames_received = callback_->Render(audio_bus, 0);
76  if (!audio_hash_ || frames_received <= 0)
77    return;
78
79  audio_hash_->Update(audio_bus, frames_received);
80}
81
82void NullAudioSink::StartAudioHashForTesting() {
83  DCHECK(!initialized_);
84  audio_hash_.reset(new AudioHash());
85}
86
87std::string NullAudioSink::GetAudioHashForTesting() {
88  return audio_hash_ ? audio_hash_->ToString() : std::string();
89}
90
91}  // namespace media
92