Add support for real audio output to mojo.

media/audio/audio_output_stream_sink.cc

+// Copyright 2014 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/audio/audio_output_stream_sink.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/location.h"
+#include "media/audio/audio_manager.h"
+
+namespace media {
+
+AudioOutputStreamSink::AudioOutputStreamSink()
+    : render_callback_(NULL),
+      audio_task_runner_(AudioManager::Get()->GetTaskRunner()),
+      stream_(NULL),
+      active_render_callback_(NULL) {
+}
+
+AudioOutputStreamSink::~AudioOutputStreamSink() {
+}
+
+void AudioOutputStreamSink::Initialize(const AudioParameters& params,
+                                       RenderCallback* callback) {
+  DCHECK(callback);
+  DCHECK(!render_callback_);
+  params_ = params;
+  render_callback_ = callback;
+}
+
+void AudioOutputStreamSink::Start() {
+  audio_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&AudioOutputStreamSink::DoStart, this));
+}
+
+void AudioOutputStreamSink::Stop() {
+  ClearCallback();
+  audio_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&AudioOutputStreamSink::DoStop, this));
+}
+
+void AudioOutputStreamSink::Pause() {
+  ClearCallback();
+  audio_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&AudioOutputStreamSink::DoPause, this));
+}
+
+void AudioOutputStreamSink::Play() {
+  base::AutoLock al(callback_lock_);
+  active_render_callback_ = render_callback_;
+  audio_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&AudioOutputStreamSink::DoPlay, this));
+}
+
+bool AudioOutputStreamSink::SetVolume(double volume) {
+  audio_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&AudioOutputStreamSink::DoSetVolume, this, volume));
+  return true;
+};
+
+int AudioOutputStreamSink::OnMoreData(AudioBus* dest,
+                                      uint32 total_bytes_delay) {
+  // Note: Runs on the audio thread created by the OS.
+  base::AutoLock al(callback_lock_);
+  if (!active_render_callback_)
+    return 0;
+
+  return active_render_callback_->Render(
+      dest, total_bytes_delay * 1000.0 / params_.GetBytesPerSecond());
+}
+
+void AudioOutputStreamSink::OnError(AudioOutputStream* stream) {
+  // Note: Runs on the audio thread created by the OS.
+  base::AutoLock al(callback_lock_);
+  if (active_render_callback_)
+    active_render_callback_->OnRenderError();
+}
+
+void AudioOutputStreamSink::DoStart() {
+  DCHECK(audio_task_runner_->BelongsToCurrentThread());
+
+  // Create an AudioOutputStreamProxy which will handle any and all resampling
+  // necessary to generate a low latency output stream.
+  stream_ =
+      AudioManager::Get()->MakeAudioOutputStreamProxy(params_, std::string());
+  if (!stream_ || !stream_->Open()) {
+    render_callback_->OnRenderError();
+    if (stream_)
+      stream_->Close();
+    stream_ = NULL;
+  }
+}
+
+void AudioOutputStreamSink::DoStop() {
+  DCHECK(audio_task_runner_->BelongsToCurrentThread());
+
+  if (!stream_)
+    return;
+
+  DoPause();
+  stream_->Close();
+  stream_ = NULL;
+}
+
+void AudioOutputStreamSink::DoPause() {
+  DCHECK(audio_task_runner_->BelongsToCurrentThread());
+  stream_->Stop();
+}
+
+void AudioOutputStreamSink::DoPlay() {
+  DCHECK(audio_task_runner_->BelongsToCurrentThread());
+  stream_->Start(this);
+}
+
+void AudioOutputStreamSink::DoSetVolume(double volume) {
+  DCHECK(audio_task_runner_->BelongsToCurrentThread());
+  stream_->SetVolume(volume);
+}
+
+void AudioOutputStreamSink::ClearCallback() {
+  base::AutoLock al(callback_lock_);
+  active_render_callback_ = NULL;
+}
+
+}  // namepace media