Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

media/audio/null_audio_sink.cc

+// Copyright (c) 2012 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/null_audio_sink.h"
+
+#include "base/bind.h"
+#include "base/threading/platform_thread.h"
+
+namespace media {
+
+NullAudioSink::NullAudioSink()
+    : initialized_(false),
+      playback_rate_(0.0),
+      playing_(false),
+      callback_(NULL),
+      thread_("NullAudioThread") {
+}
+
+NullAudioSink::~NullAudioSink() {
+  DCHECK(!thread_.IsRunning());
+  for (size_t i = 0; i < audio_data_.size(); ++i)
+    delete [] audio_data_[i];
+}
+
+
+void NullAudioSink::Start() {
+  if (!thread_.Start())
+    return;
+
+  thread_.message_loop()->PostTask(FROM_HERE, base::Bind(
+      &NullAudioSink::FillBufferTask, this));
+}
+
+void NullAudioSink::Stop() {
+  SetPlaying(false);
+  thread_.Stop();
+}
+
+void NullAudioSink::Play() {
+  SetPlaying(true);
+}
+
+void NullAudioSink::Pause(bool /* flush */) {
+  SetPlaying(false);
+}
+
+void NullAudioSink::SetPlaybackRate(float rate) {
+  base::AutoLock auto_lock(lock_);
+  playback_rate_ = rate;
+}
+
+bool NullAudioSink::SetVolume(double volume) {
+  // Audio is always muted.
+  return volume == 0.0;
+}
+
+void NullAudioSink::GetVolume(double* volume) {
+  // Audio is always muted.
+  *volume = 0.0;
+}
+
+void NullAudioSink::SetPlaying(bool is_playing) {
+  base::AutoLock auto_lock(lock_);
+  playing_ = is_playing;
+}
+
+void NullAudioSink::Initialize(const AudioParameters& params,
+                               RenderCallback* callback) {
+  DCHECK(!initialized_);
+  params_ = params;
+
+  audio_data_.reserve(params.channels());
+  for (int i = 0; i < params.channels(); ++i) {
+    float* channel_data = new float[params.frames_per_buffer()];
+    audio_data_.push_back(channel_data);
+  }
+
+  callback_ = callback;
+  initialized_ = true;
+}
+
+void NullAudioSink::FillBufferTask() {
+  base::AutoLock auto_lock(lock_);
+
+  base::TimeDelta delay;
+  // Only consume buffers when actually playing.
+  if (playing_)  {
+    DCHECK_GT(playback_rate_, 0.0f);
+    int requested_frames = params_.frames_per_buffer();
+    int frames_received = callback_->Render(audio_data_, requested_frames, 0);
+    int frames_per_millisecond =
+        params_.sample_rate() / base::Time::kMillisecondsPerSecond;
+
+    // Calculate our sleep duration, taking playback rate into consideration.
+    delay = base::TimeDelta::FromMilliseconds(
+        frames_received / (frames_per_millisecond * playback_rate_));
+  } else {
+    // If paused, sleep for 10 milliseconds before polling again.
+    delay = base::TimeDelta::FromMilliseconds(10);
+  }
+
+  // Sleep for at least one millisecond so we don't spin the CPU.
+  MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&NullAudioSink::FillBufferTask, this),
+      std::max(delay, base::TimeDelta::FromMilliseconds(1)));
+}
+
+}  // namespace media