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