Support for AudioContextOptions latencyHint.

third_party/WebKit/Source/modules/webaudio/DefaultAudioDestinationNode.cpp

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 13 matching lines @@
  */
 
 #include "modules/webaudio/DefaultAudioDestinationNode.h"
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/dom/ExceptionCode.h"
 #include "modules/webaudio/BaseAudioContext.h"
 
 namespace blink {
 
-DefaultAudioDestinationHandler::DefaultAudioDestinationHandler(AudioNode& node)
-    : AudioDestinationHandler(node, AudioDestination::hardwareSampleRate()),
-      m_numberOfInputChannels(0) {
+DefaultAudioDestinationHandler::DefaultAudioDestinationHandler(
+    AudioNode& node,
+    const WebAudioLatencyHint& latencyHint)
+    : AudioDestinationHandler(node),
+      m_numberOfInputChannels(0),
+      m_latencyHint(latencyHint) {
   // Node-specific default mixing rules.
   m_channelCount = 2;
   setInternalChannelCountMode(Explicit);
   setInternalChannelInterpretation(AudioBus::Speakers);
 }
 
 PassRefPtr<DefaultAudioDestinationHandler>
-DefaultAudioDestinationHandler::create(AudioNode& node) {
-  return adoptRef(new DefaultAudioDestinationHandler(node));
+DefaultAudioDestinationHandler::create(AudioNode& node,
+                                       const WebAudioLatencyHint& latencyHint) {
+  return adoptRef(new DefaultAudioDestinationHandler(node, latencyHint));
 }
 
 DefaultAudioDestinationHandler::~DefaultAudioDestinationHandler() {
   DCHECK(!isInitialized());
 }
 
 void DefaultAudioDestinationHandler::dispose() {
   uninitialize();
   AudioDestinationHandler::dispose();
 }
@@ skipping 12 matching lines @@
   if (!isInitialized())
     return;
 
   m_destination->stop();
   m_numberOfInputChannels = 0;
 
   AudioHandler::uninitialize();
 }
 
 void DefaultAudioDestinationHandler::createDestination() {
-  float hardwareSampleRate = AudioDestination::hardwareSampleRate();
-  VLOG(1) << ">>>> hardwareSampleRate = " << hardwareSampleRate;
-
   m_destination = AudioDestination::create(
       *this, m_inputDeviceId, m_numberOfInputChannels, channelCount(),
-      hardwareSampleRate, context()->getSecurityOrigin());
+      m_latencyHint, context()->getSecurityOrigin());
 }
 
 void DefaultAudioDestinationHandler::startRendering() {
   DCHECK(isInitialized());
   if (isInitialized()) {
     DCHECK(!m_destination->isPlaying());
     m_destination->start();
   }
 }
 
@@ skipping 32 matching lines @@
 
   if (!exceptionState.hadException() &&
       this->channelCount() != oldChannelCount && isInitialized()) {
     // Re-create destination.
     m_destination->stop();
     createDestination();
     m_destination->start();
   }
 }
 
+double DefaultAudioDestinationHandler::sampleRate() const {
+  return m_destination ? m_destination->sampleRate() : 0;

[o1ka, 2016/12/02 12:02:13]

How valid is the case when |m_destination| is null?
There are quite a lot of places where we divide by sample rate.
Do we really want to defer the crash?

+}
+
+int DefaultAudioDestinationHandler::framesPerBuffer() const {
+  return m_destination ? m_destination->framesPerBuffer() : 0;
+}
+
 // ----------------------------------------------------------------
 
 DefaultAudioDestinationNode::DefaultAudioDestinationNode(
-    BaseAudioContext& context)
+    BaseAudioContext& context,
+    const WebAudioLatencyHint& latencyHint)
     : AudioDestinationNode(context) {
-  setHandler(DefaultAudioDestinationHandler::create(*this));
+  setHandler(DefaultAudioDestinationHandler::create(*this, latencyHint));
 }
 
 DefaultAudioDestinationNode* DefaultAudioDestinationNode::create(
-    BaseAudioContext* context) {
-  return new DefaultAudioDestinationNode(*context);
+    BaseAudioContext* context,
+    const WebAudioLatencyHint& latencyHint) {
+  return new DefaultAudioDestinationNode(*context, latencyHint);
 }
 
 }  // namespace blink