Reland: MediaCaptureFromElement: add support for audio captureStream().

media/blink/webaudiosourceprovider_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/blink/webaudiosourceprovider_impl.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 32 matching lines @@
  private:
   base::Lock& lock_;
   const bool acquired_;
   DISALLOW_COPY_AND_ASSIGN(AutoTryLock);
 };
 
 }  // namespace
 
 // TeeFilter is a RenderCallback implementation that allows for a client to get
 // a copy of the data being rendered by the |renderer_| on Render(). This class
-// also holds to the necessary audio parameters.
+// also holds on to the necessary audio parameters.
 class WebAudioSourceProviderImpl::TeeFilter
     : public AudioRendererSink::RenderCallback {
  public:
-  TeeFilter(AudioRendererSink::RenderCallback* renderer,
-            int channels,
-            int sample_rate)
-      : renderer_(renderer), channels_(channels), sample_rate_(sample_rate) {
-    DCHECK(renderer_);
+  TeeFilter() : renderer_(nullptr), channels_(0), sample_rate_(0) {}
+  ~TeeFilter() override {}
+
+  void Initialize(AudioRendererSink::RenderCallback* renderer,
+                  int channels,
+                  int sample_rate) {
+    DCHECK(renderer);
+    renderer_ = renderer;
+    channels_ = channels;
+    sample_rate_ = sample_rate;
   }
-  ~TeeFilter() override {}
 
   // AudioRendererSink::RenderCallback implementation.
   // These are forwarders to |renderer_| and are here to allow for a client to
   // get a copy of the rendered audio by SetCopyAudioCallback().
   int Render(AudioBus* audio_bus,
              uint32_t delay_milliseconds,
              uint32_t frames_skipped) override;
   void OnRenderError() override;
 
+  bool IsInitialized() const { return !!renderer_; }
   int channels() const { return channels_; }
   int sample_rate() const { return sample_rate_; }
-  void set_copy_audio_bus_callback(
-      const WebAudioSourceProviderImpl::CopyAudioCB& callback) {
+  void set_copy_audio_bus_callback(const CopyAudioCB& callback) {
     copy_audio_bus_callback_ = callback;
   }
 
  private:
-  AudioRendererSink::RenderCallback* const renderer_;
-  const int channels_;
-  const int sample_rate_;
+  AudioRendererSink::RenderCallback* renderer_;
+  int channels_;
+  int sample_rate_;
 
-  WebAudioSourceProviderImpl::CopyAudioCB copy_audio_bus_callback_;
+  CopyAudioCB copy_audio_bus_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(TeeFilter);
 };
 
 WebAudioSourceProviderImpl::WebAudioSourceProviderImpl(
     const scoped_refptr<SwitchableAudioRendererSink>& sink)
     : volume_(1.0),
       state_(kStopped),
       client_(nullptr),
       sink_(sink),
+      tee_filter_(new TeeFilter()),
       weak_factory_(this) {}
 
 WebAudioSourceProviderImpl::~WebAudioSourceProviderImpl() {
 }
 
 void WebAudioSourceProviderImpl::setClient(
     blink::WebAudioSourceProviderClient* client) {
   base::AutoLock auto_lock(sink_lock_);
   if (client && client != client_) {
     // Detach the audio renderer from normal playback.
     sink_->Stop();
 
     // The client will now take control by calling provideInput() periodically.
     client_ = client;
 
     set_format_cb_ = BindToCurrentLoop(base::Bind(
         &WebAudioSourceProviderImpl::OnSetFormat, weak_factory_.GetWeakPtr()));
 
-    // If |tee_filter_| is set, it means we have been Initialize()d - then run
-    // |set_format_cb_| to send |client_| the current format info. Otherwise
-    // |set_format_cb_| will get called when Initialize() is called.
-    // Note: Always using |set_format_cb_| ensures we have the same locking
-    // order when calling into |client_|.
-    if (tee_filter_)
+    // If |tee_filter_| is Initialize()d - then run |set_format_cb_| to send
+    // |client_| the current format info. Otherwise |set_format_cb_| will get
+    // called when Initialize() is called. Note: Always using |set_format_cb_|
+    // ensures we have the same locking order when calling into |client_|.
+    if (tee_filter_->IsInitialized())  // ???

[DaleCurtis, 2016/05/23 18:37:18]

Remove ???

[mcasas, 2016/05/23 19:00:13]

Done.

       base::ResetAndReturn(&set_format_cb_).Run();
   } else if (!client && client_) {
     // Restore normal playback.
     client_ = nullptr;
     sink_->SetVolume(volume_);
     if (state_ >= kStarted)
       sink_->Start();
     if (state_ >= kPlaying)
       sink_->Play();
   }
@@ skipping 14 matching lines @@
   // Use a try lock to avoid contention in the real-time audio thread.
   AutoTryLock auto_try_lock(sink_lock_);
   if (!auto_try_lock.locked() || state_ != kPlaying) {
     // Provide silence if we failed to acquire the lock or the source is not
     // running.
     bus_wrapper_->Zero();
     return;
   }
 
   DCHECK(client_);
-  DCHECK(tee_filter_);
   DCHECK_EQ(tee_filter_->channels(), bus_wrapper_->channels());
   const int frames = tee_filter_->Render(bus_wrapper_.get(), 0, 0);
   if (frames < incoming_number_of_frames)
     bus_wrapper_->ZeroFramesPartial(frames, incoming_number_of_frames - frames);
 
   bus_wrapper_->Scale(volume_);
 }
 
 void WebAudioSourceProviderImpl::Start() {
   base::AutoLock auto_lock(sink_lock_);
@@ skipping 49 matching lines @@
     callback.Run(media::OUTPUT_DEVICE_STATUS_ERROR_INTERNAL);
   else
     sink_->SwitchOutputDevice(device_id, security_origin, callback);
 }
 
 void WebAudioSourceProviderImpl::Initialize(const AudioParameters& params,
                                             RenderCallback* renderer) {
   base::AutoLock auto_lock(sink_lock_);
   DCHECK_EQ(state_, kStopped);
 
-  tee_filter_ = base::WrapUnique(
-      new TeeFilter(renderer, params.channels(), params.sample_rate()));
+  tee_filter_->Initialize(renderer, params.channels(), params.sample_rate());
 
   sink_->Initialize(params, tee_filter_.get());
 
   if (!set_format_cb_.is_null())
     base::ResetAndReturn(&set_format_cb_).Run();
 }
 
 void WebAudioSourceProviderImpl::SetCopyAudioCallback(
     const CopyAudioCB& callback) {
   DCHECK(!callback.is_null());
+
+  // Use |sink_lock_| to protect |tee_filter_| too since they go in lockstep.
+  base::AutoLock auto_lock(sink_lock_);
+
   DCHECK(tee_filter_);
   tee_filter_->set_copy_audio_bus_callback(callback);
 }
 
 void WebAudioSourceProviderImpl::ClearCopyAudioCallback() {
   DCHECK(tee_filter_);
   tee_filter_->set_copy_audio_bus_callback(CopyAudioCB());
 }
 
+int WebAudioSourceProviderImpl::RenderForTesting(AudioBus* audio_bus) {
+  return tee_filter_->Render(audio_bus, 0, 0);
+}
+
 void WebAudioSourceProviderImpl::OnSetFormat() {
   base::AutoLock auto_lock(sink_lock_);
   if (!client_)
     return;
 
   // Inform Blink about the audio stream format.
   client_->setFormat(tee_filter_->channels(), tee_filter_->sample_rate());
 }
 
-int WebAudioSourceProviderImpl::RenderForTesting(AudioBus* audio_bus) {
-  return tee_filter_->Render(audio_bus, 0, 0);
-}
-
 int WebAudioSourceProviderImpl::TeeFilter::Render(AudioBus* audio_bus,
                                                   uint32_t delay_milliseconds,
                                                   uint32_t frames_skipped) {
+  if (!renderer_)

[DaleCurtis, 2016/05/23 18:37:18]

This should be impossible, no?

[mcasas, 2016/05/23 19:00:13]

It could be possible if we get data before the
|renderer_| has been set, but seeing your reaction
I believe is is enforced in the class contract. 
Changed for a DCHECK.

+    return 0;
+
   const int num_rendered_frames =
       renderer_->Render(audio_bus, delay_milliseconds, frames_skipped);
 
   if (!copy_audio_bus_callback_.is_null()) {
     std::unique_ptr<AudioBus> bus_copy =
         AudioBus::Create(audio_bus->channels(), audio_bus->frames());
     audio_bus->CopyTo(bus_copy.get());
     copy_audio_bus_callback_.Run(std::move(bus_copy), delay_milliseconds,
                                  sample_rate_);
   }
 
   return num_rendered_frames;
 }
 
 void WebAudioSourceProviderImpl::TeeFilter::OnRenderError() {
-  renderer_->OnRenderError();
+  if (renderer_)

[DaleCurtis, 2016/05/23 18:37:18]

Ditto.

[mcasas, 2016/05/23 19:00:13]

Acknowledged.

+    renderer_->OnRenderError();
 }
 
 }  // namespace media