media/blink/webaudiosourceprovider_impl.cc

   1 // Copyright 2013 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/blink/webaudiosourceprovider_impl.h"
   6
   7 #include <vector>
   8
   9 #include "base/bind.h"
  10 #include "base/callback_helpers.h"
  11 #include "base/logging.h"
  12 #include "media/base/bind_to_current_loop.h"
  13 #include "third_party/WebKit/public/platform/WebAudioSourceProviderClient.h"
  14
  15 using blink::WebVector;
  16
  17 namespace media {
  18
  19 namespace {
  20
  21 // Simple helper class for Try() locks.  Lock is Try()'d on construction and
  22 // must be checked via the locked() attribute.  If acquisition was successful
  23 // the lock will be released upon destruction.
  24 // TODO(dalecurtis): This should probably move to base/ if others start using
  25 // this pattern.
  26 class AutoTryLock {
  27  public:
  28   explicit AutoTryLock(base::Lock& lock)
  29       : lock_(lock),
  30         acquired_(lock_.Try()) {}
  31
  32   bool locked() const { return acquired_; }
  33
  34   ~AutoTryLock() {
  35     if (acquired_) {
  36       lock_.AssertAcquired();
  37       lock_.Release();
  38     }
  39   }
  40
  41  private:
  42   base::Lock& lock_;
  43   const bool acquired_;
  44   DISALLOW_COPY_AND_ASSIGN(AutoTryLock);
  45 };
  46
  47 }  // namespace
  48
  49 WebAudioSourceProviderImpl::WebAudioSourceProviderImpl(
  50     const scoped_refptr<AudioRendererSink>& sink)
  51     : channels_(0),
  52       sample_rate_(0),
  53       volume_(1.0),
  54       state_(kStopped),
  55       renderer_(NULL),
  56       client_(NULL),
  57       sink_(sink),
  58       weak_factory_(this) {}
  59
  60 WebAudioSourceProviderImpl::~WebAudioSourceProviderImpl() {
  61 }
  62
  63 void WebAudioSourceProviderImpl::setClient(
  64     blink::WebAudioSourceProviderClient* client) {
  65   base::AutoLock auto_lock(sink_lock_);
  66   if (client && client != client_) {
  67     // Detach the audio renderer from normal playback.
  68     sink_->Stop();
  69
  70     // The client will now take control by calling provideInput() periodically.
  71     client_ = client;
  72
  73     set_format_cb_ = BindToCurrentLoop(base::Bind(
  74         &WebAudioSourceProviderImpl::OnSetFormat, weak_factory_.GetWeakPtr()));
  75
  76     // If |renderer_| is set, then run |set_format_cb_| to send |client_|
  77     // the current format info. If |renderer_| is not set, then |set_format_cb_|
  78     // will get called when Initialize() is called.
  79     // Note: Always using |set_format_cb_| ensures we have the same
  80     // locking order when calling into |client_|.
  81     if (renderer_)
  82       base::ResetAndReturn(&set_format_cb_).Run();
  83   } else if (!client && client_) {
  84     // Restore normal playback.
  85     client_ = NULL;
  86     sink_->SetVolume(volume_);
  87     if (state_ >= kStarted)
  88       sink_->Start();
  89     if (state_ >= kPlaying)
  90       sink_->Play();
  91   }
  92 }
  93
  94 void WebAudioSourceProviderImpl::provideInput(
  95     const WebVector<float*>& audio_data, size_t number_of_frames) {
  96   if (!bus_wrapper_ ||
  97       static_cast<size_t>(bus_wrapper_->channels()) != audio_data.size()) {
  98     bus_wrapper_ = AudioBus::CreateWrapper(static_cast<int>(audio_data.size()));
  99   }
 100
 101   bus_wrapper_->set_frames(static_cast<int>(number_of_frames));
 102   for (size_t i = 0; i < audio_data.size(); ++i)
 103     bus_wrapper_->SetChannelData(static_cast<int>(i), audio_data[i]);
 104
 105   // Use a try lock to avoid contention in the real-time audio thread.
 106   AutoTryLock auto_try_lock(sink_lock_);
 107   if (!auto_try_lock.locked() || state_ != kPlaying) {
 108     // Provide silence if we failed to acquire the lock or the source is not
 109     // running.
 110     bus_wrapper_->Zero();
 111     return;
 112   }
 113
 114   DCHECK(renderer_);
 115   DCHECK(client_);
 116   DCHECK_EQ(channels_, bus_wrapper_->channels());
 117   const int frames = renderer_->Render(bus_wrapper_.get(), 0);
 118   if (frames < static_cast<int>(number_of_frames)) {
 119     bus_wrapper_->ZeroFramesPartial(
 120         frames,
 121         static_cast<int>(number_of_frames - frames));
 122   }
 123
 124   bus_wrapper_->Scale(volume_);
 125 }
 126
 127 void WebAudioSourceProviderImpl::Start() {
 128   base::AutoLock auto_lock(sink_lock_);
 129   DCHECK_EQ(state_, kStopped);
 130   state_ = kStarted;
 131   if (!client_)
 132     sink_->Start();
 133 }
 134
 135 void WebAudioSourceProviderImpl::Stop() {
 136   base::AutoLock auto_lock(sink_lock_);
 137   state_ = kStopped;
 138   if (!client_)
 139     sink_->Stop();
 140 }
 141
 142 void WebAudioSourceProviderImpl::Play() {
 143   base::AutoLock auto_lock(sink_lock_);
 144   DCHECK_EQ(state_, kStarted);
 145   state_ = kPlaying;
 146   if (!client_)
 147     sink_->Play();
 148 }
 149
 150 void WebAudioSourceProviderImpl::Pause() {
 151   base::AutoLock auto_lock(sink_lock_);
 152   DCHECK(state_ == kPlaying || state_ == kStarted);
 153   state_ = kStarted;
 154   if (!client_)
 155     sink_->Pause();
 156 }
 157
 158 bool WebAudioSourceProviderImpl::SetVolume(double volume) {
 159   base::AutoLock auto_lock(sink_lock_);
 160   volume_ = volume;
 161   if (!client_)
 162     sink_->SetVolume(volume);
 163   return true;
 164 }
 165
 166 void WebAudioSourceProviderImpl::Initialize(
 167     const AudioParameters& params,
 168     RenderCallback* renderer) {
 169   base::AutoLock auto_lock(sink_lock_);
 170   CHECK(!renderer_);
 171   renderer_ = renderer;
 172
 173   DCHECK_EQ(state_, kStopped);
 174   sink_->Initialize(params, renderer);
 175
 176   // Keep track of the format in case the client hasn't yet been set.
 177   channels_ = params.channels();
 178   sample_rate_ = params.sample_rate();
 179
 180   if (!set_format_cb_.is_null())
 181     base::ResetAndReturn(&set_format_cb_).Run();
 182 }
 183
 184 void WebAudioSourceProviderImpl::OnSetFormat() {
 185   base::AutoLock auto_lock(sink_lock_);
 186   if (!client_)
 187     return;
 188
 189   // Inform Blink about the audio stream format.
 190   client_->setFormat(channels_, sample_rate_);
 191 }
 192
 193 }  // namespace media