Very early implementation for HTMLMediaElement / Web Audio API integration

content/renderer/render_audiosourceprovider.cc

+// Copyright (c) 2010 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 "content/renderer/render_audiosourceprovider.h"
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+using namespace std;
+using WebKit::WebVector;
+
+RenderAudioSourceProvider::RenderAudioSourceProvider(
+    media::AudioRendererSink::RenderCallback* callback)
+    : is_running_(false),
+      volume_(1.0),
+      callback_(callback) {
+  callback->SetAudioRendererSink(this);
+}
+
+bool RenderAudioSourceProvider::Start() {
+  if (!is_running_) {
+    is_running_ = true;
+  }
+  return true;
+}
+
+bool RenderAudioSourceProvider::Stop() {
+  if (is_running_) {
+    is_running_ = false;
+  }
+  return true;
+}
+
+bool RenderAudioSourceProvider::SetVolume(double volume) {
+  volume_ = volume;
+  return true;
+}
+
+void RenderAudioSourceProvider::provideInput(
+    const WebVector<float*>& audio_data, size_t number_of_frames) {
+  DCHECK(callback_);
+  if (callback_ && is_running_) {
+    // Wrap WebVector as regular std::vector.
+    vector<float*> v(audio_data.size());
+    for (size_t i = 0; i < audio_data.size(); ++i)
+      v[i] = audio_data[i];
+
+    // TODO(crogers): figure out if we should volume scale here or in common
+    // WebAudio code.
+    callback_->Render(v, number_of_frames, 0);
+  } else {
+    // Provide silence if the source is not running.
+    for (size_t i = 0; i < audio_data.size(); ++i) {
+      memset(audio_data[i], 0, sizeof(float) * number_of_frames);
+    }
+  }
+}