media/audio/null_audio_sink.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/null_audio_sink.h"
   6
   7 #include "base/bind.h"
   8 #include "base/message_loop/message_loop_proxy.h"
   9 #include "media/audio/fake_audio_consumer.h"
  10 #include "media/base/audio_hash.h"
  11
  12 namespace media {
  13
  14 NullAudioSink::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
  22 NullAudioSink::~NullAudioSink() {}
  23
  24 void 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
  32 void NullAudioSink::Start() {
  33   DCHECK(message_loop_->BelongsToCurrentThread());
  34   DCHECK(!playing_);
  35 }
  36
  37 void 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
  45 void 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
  57 void NullAudioSink::Pause() {
  58   DCHECK(message_loop_->BelongsToCurrentThread());
  59
  60   if (!playing_)
  61     return;
  62
  63   fake_consumer_->Stop();
  64   playing_ = false;
  65 }
  66
  67 bool NullAudioSink::SetVolume(double volume) {
  68   // Audio is always muted.
  69   return volume == 0.0;
  70 }
  71
  72 void 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
  82 void NullAudioSink::StartAudioHashForTesting() {
  83   DCHECK(!initialized_);
  84   audio_hash_.reset(new AudioHash());
  85 }
  86
  87 std::string NullAudioSink::GetAudioHashForTesting() {
  88   return audio_hash_ ? audio_hash_->ToString() : std::string();
  89 }
  90
  91 }  // namespace media