Switch AudioRenderSink::Callback to use AudioBus.

As titled, switches everything over to using the AudioBus
class instead of const std::vector<float*>.  Allows removal
of lots of crufty allocations and memsets.

BUG=114700
TEST=unit tests, layout tests, try bots.  Nothing should change.


Review URL: https://chromiumcodereview.appspot.com/10823175

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150906 0039d316-1c4b-4281-b951-d872f2087c98

22 files changed, 163 insertions, 259 deletions

diff --git a/media/audio/audio_device_thread.cc b/media/audio/audio_device_thread.cc
index 83eb0c4..3e14d3d 100644
--- a/media/audio/audio_device_thread.cc
+++ b/media/audio/audio_device_thread.cc
@@ -13,6 +13,7 @@
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "media/audio/audio_util.h"
+#include "media/base/audio_bus.h"
 
 using base::PlatformThread;
 
@@ -188,23 +189,17 @@ AudioDeviceThread::Callback::Callback(
   CHECK_NE(samples_per_ms_, 0);
 }
 
-AudioDeviceThread::Callback::~Callback() {
-  for (size_t i = 0; i < audio_data_.size(); ++i)
-    base::AlignedFree(audio_data_[i]);
-}
+AudioDeviceThread::Callback::~Callback() {}
 
 void AudioDeviceThread::Callback::InitializeOnAudioThread() {
-  DCHECK(audio_data_.empty());
+  DCHECK(!audio_bus_.get());
 
   MapSharedMemory();
   DCHECK(shared_memory_.memory() != NULL);
 
-  // Allocate buffer with a 16-byte alignment to allow SSE optimizations.
-  audio_data_.reserve(audio_parameters_.channels());
-  for (int i = 0; i < audio_parameters_.channels(); ++i) {
-    audio_data_.push_back(static_cast<float*>(base::AlignedAlloc(
-        sizeof(float) * audio_parameters_.frames_per_buffer(), 16)));
-  }
+  // TODO(dalecurtis): Instead of creating a new AudioBus and memcpy'ing into
+  // the shared memory we should wrap the shared memory.
+  audio_bus_ = AudioBus::Create(audio_parameters_);
 }
 
 }  // namespace media.
diff --git a/media/audio/audio_device_thread.h b/media/audio/audio_device_thread.h
index a50339a..d229613 100644
--- a/media/audio/audio_device_thread.h
+++ b/media/audio/audio_device_thread.h
@@ -5,10 +5,9 @@
 #ifndef MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
 #define MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
 
-#include <vector>
-
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "base/sync_socket.h"
 #include "base/synchronization/lock.h"
@@ -18,6 +17,7 @@
 class MessageLoop;
 
 namespace media {
+class AudioBus;
 
 // Data transfer between browser and render process uses a combination
 // of sync sockets and shared memory. To read from the socket and render
@@ -60,7 +60,7 @@ class MEDIA_EXPORT AudioDeviceThread {
 
     // Audio buffers that are allocated in InitializeOnAudioThread() based on
     // info from audio_parameters_.
-    std::vector<float*> audio_data_;
+    scoped_ptr<AudioBus> audio_bus_;
     base::SharedMemory shared_memory_;
     const int memory_length_;
 
diff --git a/media/audio/audio_input_device.cc b/media/audio/audio_input_device.cc
index 401042a..b1ab6f8 100644
--- a/media/audio/audio_input_device.cc
+++ b/media/audio/audio_input_device.cc
@@ -10,6 +10,7 @@
 #include "base/time.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/audio/audio_util.h"
+#include "media/base/audio_bus.h"
 
 namespace media {
 
@@ -328,24 +329,23 @@ void AudioInputDevice::AudioThreadCallback::Process(int pending_data) {
 
   int audio_delay_milliseconds = pending_data / bytes_per_ms_;
   int16* memory = reinterpret_cast<int16*>(&buffer->audio[0]);
-  const size_t number_of_frames = audio_parameters_.frames_per_buffer();
   const int bytes_per_sample = sizeof(memory[0]);
 
   // Deinterleave each channel and convert to 32-bit floating-point
   // with nominal range -1.0 -> +1.0.
-  for (int channel_index = 0; channel_index < audio_parameters_.channels();
+  for (int channel_index = 0; channel_index < audio_bus_->channels();
        ++channel_index) {
     DeinterleaveAudioChannel(memory,
-                             audio_data_[channel_index],
-                             audio_parameters_.channels(),
+                             audio_bus_->channel(channel_index),
+                             audio_bus_->channels(),
                              channel_index,
                              bytes_per_sample,
-                             number_of_frames);
+                             audio_bus_->frames());
   }
 
   // Deliver captured data to the client in floating point format
   // and update the audio-delay measurement.
-  capture_callback_->Capture(audio_data_, number_of_frames,
+  capture_callback_->Capture(audio_bus_.get(),
                              audio_delay_milliseconds, volume);
 }
 
diff --git a/media/audio/audio_input_device.h b/media/audio/audio_input_device.h
index 42d6869..ddb2535 100644
--- a/media/audio/audio_input_device.h
+++ b/media/audio/audio_input_device.h
@@ -88,8 +88,7 @@ class MEDIA_EXPORT AudioInputDevice
  public:
   class MEDIA_EXPORT CaptureCallback {
    public:
-    virtual void Capture(const std::vector<float*>& audio_data,
-                         int number_of_frames,
+    virtual void Capture(AudioBus* audio_bus,
                          int audio_delay_milliseconds,
                          double volume) = 0;
     virtual void OnCaptureError() = 0;
diff --git a/media/audio/audio_output_device.cc b/media/audio/audio_output_device.cc
index eff1a0c..994fa40 100644
--- a/media/audio/audio_output_device.cc
+++ b/media/audio/audio_output_device.cc
@@ -266,17 +266,18 @@ void AudioOutputDevice::AudioThreadCallback::Process(int pending_data) {
   TRACE_EVENT0("audio", "AudioOutputDevice::FireRenderCallback");
 
   // Update the audio-delay measurement then ask client to render audio.
-  size_t num_frames = render_callback_->Render(audio_data_,
-      audio_parameters_.frames_per_buffer(), audio_delay_milliseconds);
+  size_t num_frames = render_callback_->Render(
+      audio_bus_.get(), audio_delay_milliseconds);
 
   // Interleave, scale, and clip to int.
-  // TODO(crogers/vrk): Figure out a way to avoid the float -> int -> float
-  // conversions that happen in the <audio> and WebRTC scenarios.
-  InterleaveFloatToInt(audio_data_, shared_memory_.memory(),
-      num_frames, audio_parameters_.bits_per_sample() / 8);
+  // TODO(dalecurtis): Remove this when we have float everywhere.
+  InterleaveFloatToInt(
+      audio_bus_.get(), shared_memory_.memory(), num_frames,
+      audio_parameters_.bits_per_sample() / 8);
 
   // Let the host know we are done.
-  SetActualDataSizeInBytes(&shared_memory_, memory_length_,
+  SetActualDataSizeInBytes(
+      &shared_memory_, memory_length_,
       num_frames * audio_parameters_.GetBytesPerFrame());
 }
 
diff --git a/media/audio/audio_output_device_unittest.cc b/media/audio/audio_output_device_unittest.cc
index 8133f34..152e958 100644
--- a/media/audio/audio_output_device_unittest.cc
+++ b/media/audio/audio_output_device_unittest.cc
@@ -35,9 +35,7 @@ class MockRenderCallback : public AudioRendererSink::RenderCallback {
   MockRenderCallback() {}
   virtual ~MockRenderCallback() {}
 
-  MOCK_METHOD3(Render, int(const std::vector<float*>& audio_data,
-                           int number_of_frames,
-                           int audio_delay_milliseconds));
+  MOCK_METHOD2(Render, int(AudioBus* audio_bus, int audio_delay_milliseconds));
   MOCK_METHOD0(OnRenderError, void());
 };
 
@@ -87,19 +85,6 @@ ACTION_P(QuitLoop, loop) {
   loop->PostTask(FROM_HERE, MessageLoop::QuitClosure());
 }
 
-// Zeros out |number_of_frames| in all channel buffers pointed to by
-// the |audio_data| vector.
-void ZeroAudioData(int number_of_frames,
-                   const std::vector<float*>& audio_data) {
-  std::vector<float*>::const_iterator it = audio_data.begin();
-  for (; it != audio_data.end(); ++it) {
-    float* channel = *it;
-    for (int j = 0; j < number_of_frames; ++j) {
-      channel[j] = 0.0f;
-    }
-  }
-}
-
 }  // namespace.
 
 class AudioOutputDeviceTest : public testing::Test {
@@ -222,21 +207,10 @@ TEST_F(AudioOutputDeviceTest, CreateStream) {
   // So, for the sake of this test, we consider the call to Render a sign
   // of success and quit the loop.
 
-  // A note on the call to ZeroAudioData():
-  // Valgrind caught a bug in AudioOutputDevice::AudioThreadCallback::Process()
-  // whereby we always interleaved all the frames in the buffer regardless
-  // of how many were actually rendered.  So to keep the benefits of that
-  // test, we explicitly pass 0 in here as the number of frames to
-  // ZeroAudioData().  Other tests might want to pass the requested number
-  // by using WithArgs<1, 0>(Invoke(&ZeroAudioData)) and set the return
-  // value accordingly.
   const int kNumberOfFramesToProcess = 0;
 
-  EXPECT_CALL(callback_, Render(_, _, _))
+  EXPECT_CALL(callback_, Render(_, _))
       .WillOnce(DoAll(
-          WithArgs<0>(Invoke(
-              testing::CreateFunctor(&ZeroAudioData,
-                  kNumberOfFramesToProcess))),
           QuitLoop(io_loop_.message_loop_proxy()),
           Return(kNumberOfFramesToProcess)));
 
diff --git a/media/audio/audio_util.cc b/media/audio/audio_util.cc
index a8ce2b5..d54f277 100644
--- a/media/audio/audio_util.cc
+++ b/media/audio/audio_util.cc
@@ -22,6 +22,7 @@
 #include "base/time.h"
 #include "media/audio/audio_parameters.h"
 #include "media/audio/audio_util.h"
+#include "media/base/audio_bus.h"
 
 #if defined(OS_MACOSX)
 #include "media/audio/mac/audio_low_latency_input_mac.h"
@@ -230,7 +231,7 @@ bool DeinterleaveAudioChannel(void* source,
 // |Format| is the destination type, |Fixed| is a type larger than |Format|
 // such that operations can be made without overflowing.
 template<class Format, class Fixed>
-static void InterleaveFloatToInt(const std::vector<float*>& source,
+static void InterleaveFloatToInt(const AudioBus* source,
                                  void* dst_bytes, size_t number_of_frames) {
   Format* destination = reinterpret_cast<Format*>(dst_bytes);
   Fixed max_value = std::numeric_limits<Format>::max();
@@ -243,9 +244,9 @@ static void InterleaveFloatToInt(const std::vector<float*>& source,
     min_value = -(bias - 1);
   }
 
-  int channels = source.size();
+  int channels = source->channels();
   for (int i = 0; i < channels; ++i) {
-    float* channel_data = source[i];
+    const float* channel_data = source->channel(i);
     for (size_t j = 0; j < number_of_frames; ++j) {
       Fixed sample = max_value * channel_data[j];
       if (sample > max_value)
@@ -258,7 +259,7 @@ static void InterleaveFloatToInt(const std::vector<float*>& source,
   }
 }
 
-void InterleaveFloatToInt(const std::vector<float*>& source, void* dst,
+void InterleaveFloatToInt(const AudioBus* source, void* dst,
                           size_t number_of_frames, int bytes_per_sample) {
   switch (bytes_per_sample) {
     case 1:
diff --git a/media/audio/audio_util.h b/media/audio/audio_util.h
index 4ac0ef6..d25fdf9 100644
--- a/media/audio/audio_util.h
+++ b/media/audio/audio_util.h
@@ -6,7 +6,6 @@
 #define MEDIA_AUDIO_AUDIO_UTIL_H_
 
 #include <string>
-#include <vector>
 
 #include "base/basictypes.h"
 #include "media/base/channel_layout.h"
@@ -17,6 +16,7 @@ class SharedMemory;
 }
 
 namespace media {
+class AudioBus;
 
 // For all audio functions 3 audio formats are supported:
 // 8 bits unsigned 0 to 255.
@@ -86,7 +86,7 @@ MEDIA_EXPORT bool DeinterleaveAudioChannel(void* source,
 // The size of the |source| vector determines the number of channels.
 // The |destination| buffer is assumed to be large enough to hold the
 // result. Thus it must be at least size: number_of_frames * source.size()
-MEDIA_EXPORT void InterleaveFloatToInt(const std::vector<float*>& source,
+MEDIA_EXPORT void InterleaveFloatToInt(const AudioBus* audio_bus,
                                        void* destination,
                                        size_t number_of_frames,
                                        int bytes_per_sample);
diff --git a/media/audio/null_audio_sink.cc b/media/audio/null_audio_sink.cc
index d98aa63..eab0479 100644
--- a/media/audio/null_audio_sink.cc
+++ b/media/audio/null_audio_sink.cc
@@ -24,15 +24,11 @@ void NullAudioSink::Initialize(const AudioParameters& params,
   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);
-  }
+  audio_bus_ = AudioBus::Create(params_);
 
   if (hash_audio_for_testing_) {
-    md5_channel_contexts_.reset(new base::MD5Context[params.channels()]);
-    for (int i = 0; i < params.channels(); i++)
+    md5_channel_contexts_.reset(new base::MD5Context[params_.channels()]);
+    for (int i = 0; i < params_.channels(); i++)
       base::MD5Init(&md5_channel_contexts_[i]);
   }
 
@@ -73,8 +69,6 @@ void NullAudioSink::SetPlaying(bool is_playing) {
 
 NullAudioSink::~NullAudioSink() {
   DCHECK(!thread_.IsRunning());
-  for (size_t i = 0; i < audio_data_.size(); ++i)
-    delete [] audio_data_[i];
 }
 
 void NullAudioSink::FillBufferTask() {
@@ -83,16 +77,15 @@ void NullAudioSink::FillBufferTask() {
   base::TimeDelta delay;
   // Only consume buffers when actually playing.
   if (playing_)  {
-    int requested_frames = params_.frames_per_buffer();
-    int frames_received = callback_->Render(audio_data_, requested_frames, 0);
+    int frames_received = callback_->Render(audio_bus_.get(), 0);
     int frames_per_millisecond =
         params_.sample_rate() / base::Time::kMillisecondsPerSecond;
 
     if (hash_audio_for_testing_ && frames_received > 0) {
       DCHECK_EQ(sizeof(float), sizeof(uint32));
-      int channels = audio_data_.size();
+      int channels = audio_bus_->channels();
       for (int channel_idx = 0; channel_idx < channels; ++channel_idx) {
-        float* channel = audio_data_[channel_idx];
+        float* channel = audio_bus_->channel(channel_idx);
         for (int frame_idx = 0; frame_idx < frames_received; frame_idx++) {
           // Convert float to uint32 w/o conversion loss.
           uint32 frame = base::ByteSwapToLE32(
@@ -135,7 +128,7 @@ std::string NullAudioSink::GetAudioHashForTesting() {
 
   // Hash all channels into the first channel.
   base::MD5Digest digest;
-  for (size_t i = 1; i < audio_data_.size(); i++) {
+  for (int i = 1; i < audio_bus_->channels(); i++) {
     base::MD5Final(&digest, &md5_channel_contexts_[i]);
     base::MD5Update(&md5_channel_contexts_[0], base::StringPiece(
         reinterpret_cast<char*>(&digest), sizeof(base::MD5Digest)));
diff --git a/media/audio/null_audio_sink.h b/media/audio/null_audio_sink.h
index db32df0..c528473 100644
--- a/media/audio/null_audio_sink.h
+++ b/media/audio/null_audio_sink.h
@@ -13,13 +13,13 @@
 // audio device or we haven't written an audio implementation for a particular
 // platform yet.
 
-#include <vector>
-
 #include "base/md5.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/threading/thread.h"
 #include "media/base/audio_renderer_sink.h"
 
 namespace media {
+class AudioBus;
 
 class MEDIA_EXPORT NullAudioSink
     : NON_EXPORTED_BASE(public AudioRendererSink) {
@@ -53,7 +53,7 @@ class MEDIA_EXPORT NullAudioSink
   void SetPlaying(bool is_playing);
 
   // A buffer passed to FillBuffer to advance playback.
-  std::vector<float*> audio_data_;
+  scoped_ptr<AudioBus> audio_bus_;
 
   AudioParameters params_;
   bool initialized_;
diff --git a/media/base/audio_renderer_mixer.cc b/media/base/audio_renderer_mixer.cc
index 1ca2f39..503f139 100644
--- a/media/base/audio_renderer_mixer.cc
+++ b/media/base/audio_renderer_mixer.cc
@@ -46,11 +46,6 @@ AudioRendererMixer::~AudioRendererMixer() {
   // AudioRendererSinks must be stopped before being destructed.
   audio_sink_->Stop();
 
-  // Clean up |mixer_input_audio_data_|.
-  for (size_t i = 0; i < mixer_input_audio_data_.size(); ++i)
-    base::AlignedFree(mixer_input_audio_data_[i]);
-  mixer_input_audio_data_.clear();
-
   // Ensures that all mixer inputs have stopped themselves prior to destruction
   // and have called RemoveMixerInput().
   DCHECK_EQ(mixer_inputs_.size(), 0U);
@@ -68,45 +63,40 @@ void AudioRendererMixer::RemoveMixerInput(
   mixer_inputs_.erase(input);
 }
 
-int AudioRendererMixer::Render(const std::vector<float*>& audio_data,
-                               int number_of_frames,
+int AudioRendererMixer::Render(AudioBus* audio_bus,
                                int audio_delay_milliseconds) {
   current_audio_delay_milliseconds_ = audio_delay_milliseconds;
 
   if (resampler_.get())
-    resampler_->Resample(audio_data, number_of_frames);
+    resampler_->Resample(audio_bus, audio_bus->frames());
   else
-    ProvideInput(audio_data, number_of_frames);
+    ProvideInput(audio_bus);
 
   // Always return the full number of frames requested, ProvideInput() will pad
   // with silence if it wasn't able to acquire enough data.
-  return number_of_frames;
+  return audio_bus->frames();
 }
 
-void AudioRendererMixer::ProvideInput(const std::vector<float*>& audio_data,
-                                      int number_of_frames) {
+void AudioRendererMixer::ProvideInput(AudioBus* audio_bus) {
   base::AutoLock auto_lock(mixer_inputs_lock_);
 
   // Allocate staging area for each mixer input's audio data on first call.  We
-  // won't know how much to allocate until here because of resampling.
-  if (mixer_input_audio_data_.size() == 0) {
-    mixer_input_audio_data_.reserve(audio_data.size());
-    for (size_t i = 0; i < audio_data.size(); ++i) {
-      // Allocate audio data with a 16-byte alignment for SSE optimizations.
-      mixer_input_audio_data_.push_back(static_cast<float*>(
-          base::AlignedAlloc(sizeof(float) * number_of_frames, 16)));
-    }
-    mixer_input_audio_data_size_ = number_of_frames;
+  // won't know how much to allocate until here because of resampling.  Ensure
+  // our intermediate AudioBus is sized exactly as the original.  Resize should
+  // only happen once due to the way the resampler works.
+  if (!mixer_input_audio_bus_.get() ||
+      mixer_input_audio_bus_->frames() != audio_bus->frames()) {
+    mixer_input_audio_bus_ =
+        AudioBus::Create(audio_bus->channels(), audio_bus->frames());
   }
 
   // Sanity check our inputs.
-  DCHECK_LE(number_of_frames, mixer_input_audio_data_size_);
-  DCHECK_EQ(audio_data.size(), mixer_input_audio_data_.size());
+  DCHECK_EQ(audio_bus->frames(), mixer_input_audio_bus_->frames());
+  DCHECK_EQ(audio_bus->channels(), mixer_input_audio_bus_->channels());
 
-  // Zero |audio_data| so we're mixing into a clean buffer and return silence if
+  // Zero |audio_bus| so we're mixing into a clean buffer and return silence if
   // we couldn't get enough data from our inputs.
-  for (size_t i = 0; i < audio_data.size(); ++i)
-    memset(audio_data[i], 0, number_of_frames * sizeof(*audio_data[i]));
+  audio_bus->Zero();
 
   // Have each mixer render its data into an output buffer then mix the result.
   for (AudioRendererMixerInputSet::iterator it = mixer_inputs_.begin();
@@ -121,15 +111,14 @@ void AudioRendererMixer::ProvideInput(const std::vector<float*>& audio_data,
       continue;
 
     int frames_filled = input->callback()->Render(
-        mixer_input_audio_data_, number_of_frames,
-        current_audio_delay_milliseconds_);
+        mixer_input_audio_bus_.get(), current_audio_delay_milliseconds_);
     if (frames_filled == 0)
       continue;
 
-    // Volume adjust and mix each mixer input into |audio_data| after rendering.
-    for (size_t j = 0; j < audio_data.size(); ++j) {
-       VectorFMAC(
-           mixer_input_audio_data_[j], volume, frames_filled, audio_data[j]);
+    // Volume adjust and mix each mixer input into |audio_bus| after rendering.
+    for (int i = 0; i < audio_bus->channels(); ++i) {
+       VectorFMAC(mixer_input_audio_bus_->channel(i), volume, frames_filled,
+                  audio_bus->channel(i));
     }
 
     // No need to clamp values as InterleaveFloatToInt() will take care of this
diff --git a/media/base/audio_renderer_mixer.h b/media/base/audio_renderer_mixer.h
index d293799..75b7d85 100644
--- a/media/base/audio_renderer_mixer.h
+++ b/media/base/audio_renderer_mixer.h
@@ -6,7 +6,6 @@
 #define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
 
 #include <set>
-#include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/synchronization/lock.h"
@@ -38,16 +37,14 @@ class MEDIA_EXPORT AudioRendererMixer
   FRIEND_TEST_ALL_PREFIXES(AudioRendererMixerTest, VectorFMACBenchmark);
 
   // AudioRendererSink::RenderCallback implementation.
-  virtual int Render(const std::vector<float*>& audio_data,
-                     int number_of_frames,
+  virtual int Render(AudioBus* audio_bus,
                      int audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;
 
-  // Handles mixing and volume adjustment.  Renders |number_of_frames| into
-  // |audio_data|.  When resampling is necessary, ProvideInput() will be called
+  // Handles mixing and volume adjustment.  Fully fills |audio_bus| with mixed
+  // audio data.  When resampling is necessary, ProvideInput() will be called
   // by MultiChannelResampler when more data is necessary.
-  void ProvideInput(const std::vector<float*>& audio_data,
-                    int number_of_frames);
+  void ProvideInput(AudioBus* audio_bus);
 
   // Multiply each element of |src| (up to |len|) by |scale| and add to |dest|.
   static void VectorFMAC(const float src[], float scale, int len, float dest[]);
@@ -68,8 +65,7 @@ class MEDIA_EXPORT AudioRendererMixer
   base::Lock mixer_inputs_lock_;
 
   // Vector for rendering audio data from each mixer input.
-  int mixer_input_audio_data_size_;
-  std::vector<float*> mixer_input_audio_data_;
+  scoped_ptr<AudioBus> mixer_input_audio_bus_;
 
   // Handles resampling post-mixing.
   scoped_ptr<MultiChannelResampler> resampler_;
diff --git a/media/base/audio_renderer_mixer_unittest.cc b/media/base/audio_renderer_mixer_unittest.cc
index 8394c01..35917b8 100644
--- a/media/base/audio_renderer_mixer_unittest.cc
+++ b/media/base/audio_renderer_mixer_unittest.cc
@@ -191,19 +191,8 @@ class AudioRendererMixerTest
         input_parameters_, output_parameters_, sink_));
     mixer_callback_ = sink_->callback();
 
-    // TODO(dalecurtis): If we switch to AVX/SSE optimization, we'll need to
-    // allocate these on 32-byte boundaries and ensure they're sized % 32 bytes.
-    audio_data_.reserve(output_parameters_.channels());
-    for (int i = 0; i < output_parameters_.channels(); ++i)
-      audio_data_.push_back(new float[output_parameters_.frames_per_buffer()]);
-
-    // TODO(dalecurtis): If we switch to AVX/SSE optimization, we'll need to
-    // allocate these on 32-byte boundaries and ensure they're sized % 32 bytes.
-    expected_audio_data_.reserve(output_parameters_.channels());
-    for (int i = 0; i < output_parameters_.channels(); ++i) {
-      expected_audio_data_.push_back(
-          new float[output_parameters_.frames_per_buffer()]);
-    }
+    audio_bus_ = AudioBus::Create(output_parameters_);
+    expected_audio_bus_ = AudioBus::Create(output_parameters_);
 
     // Allocate one callback for generating expected results.
     double step = kSineCycles / static_cast<double>(
@@ -241,13 +230,13 @@ class AudioRendererMixerTest
   }
 
   bool ValidateAudioData(int index, int frames, float scale) {
-    for (size_t i = 0; i < audio_data_.size(); ++i) {
+    for (int i = 0; i < audio_bus_->channels(); ++i) {
       for (int j = index; j < frames; j++) {
-        double error = fabs(
-            audio_data_[i][j] - expected_audio_data_[i][j] * scale);
+        double error = fabs(audio_bus_->channel(i)[j] -
+            expected_audio_bus_->channel(i)[j] * scale);
         if (error > epsilon_) {
-          EXPECT_NEAR(
-              expected_audio_data_[i][j] * scale, audio_data_[i][j], epsilon_)
+          EXPECT_NEAR(expected_audio_bus_->channel(i)[j] * scale,
+                      audio_bus_->channel(i)[j], epsilon_)
               << " i=" << i << ", j=" << j;
           return false;
         }
@@ -257,8 +246,6 @@ class AudioRendererMixerTest
   }
 
   bool RenderAndValidateAudioData(float scale) {
-    int request_frames = output_parameters_.frames_per_buffer();
-
     // Half fill won't be exactly half when resampling since the resampler
     // will have enough data to fill out more of the buffer based on its
     // internal buffer and kernel size.  So special case some of the checks.
@@ -269,19 +256,16 @@ class AudioRendererMixerTest
       for (size_t i = 0; i < fake_callbacks_.size(); ++i)
         fake_callbacks_[i]->set_half_fill(true);
       expected_callback_->set_half_fill(true);
-      for (size_t i = 0; i < expected_audio_data_.size(); ++i) {
-        memset(expected_audio_data_[i], 0,
-               sizeof(*expected_audio_data_[i]) * request_frames);
-      }
+      expected_audio_bus_->Zero();
     }
 
     // Render actual audio data.
-    int frames = mixer_callback_->Render(audio_data_, request_frames, 0);
-    if (frames != request_frames)
+    int frames = mixer_callback_->Render(audio_bus_.get(), 0);
+    if (frames != audio_bus_->frames())
       return false;
 
     // Render expected audio data (without scaling).
-    expected_callback_->Render(expected_audio_data_, request_frames, 0);
+    expected_callback_->Render(expected_audio_bus_.get(), 0);
 
     if (half_fill_) {
       // Verify first half of audio data for both resampling and non-resampling.
@@ -296,11 +280,12 @@ class AudioRendererMixerTest
     }
   }
 
-  // Fill |audio_data_| fully with |value|.
+  // Fill |audio_bus_| fully with |value|.
   void FillAudioData(float value) {
-    for (size_t i = 0; i < audio_data_.size(); ++i)
-      std::fill(audio_data_[i],
-                audio_data_[i] + output_parameters_.frames_per_buffer(), value);
+    for (int i = 0; i < audio_bus_->channels(); ++i) {
+      std::fill(audio_bus_->channel(i),
+                audio_bus_->channel(i) + audio_bus_->frames(), value);
+    }
   }
 
   // Verify silence when mixer inputs are in pre-Start() and post-Start().
@@ -414,26 +399,21 @@ class AudioRendererMixerTest
       mixer_inputs_[i]->Stop();
     }
 
-    // Verify we get silence back; fill |audio_data_| before hand to be sure.
+    // Verify we get silence back; fill |audio_bus_| before hand to be sure.
     FillAudioData(1.0f);
     EXPECT_TRUE(RenderAndValidateAudioData(0.0f));
   }
 
  protected:
-  virtual ~AudioRendererMixerTest() {
-    for (size_t i = 0; i < audio_data_.size(); ++i)
-      delete [] audio_data_[i];
-    for (size_t i = 0; i < expected_audio_data_.size(); ++i)
-      delete [] expected_audio_data_[i];
-  }
+  virtual ~AudioRendererMixerTest() {}
 
   scoped_refptr<MockAudioRendererSink> sink_;
   scoped_ptr<AudioRendererMixer> mixer_;
   AudioRendererSink::RenderCallback* mixer_callback_;
   AudioParameters input_parameters_;
   AudioParameters output_parameters_;
-  std::vector<float*> audio_data_;
-  std::vector<float*> expected_audio_data_;
+  scoped_ptr<AudioBus> audio_bus_;
+  scoped_ptr<AudioBus> expected_audio_bus_;
   std::vector< scoped_refptr<AudioRendererMixerInput> > mixer_inputs_;
   ScopedVector<FakeAudioRenderCallback> fake_callbacks_;
   scoped_ptr<FakeAudioRenderCallback> expected_callback_;
diff --git a/media/base/audio_renderer_sink.h b/media/base/audio_renderer_sink.h
index 8786fe1..c5f43df 100644
--- a/media/base/audio_renderer_sink.h
+++ b/media/base/audio_renderer_sink.h
@@ -9,6 +9,7 @@
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "media/audio/audio_parameters.h"
+#include "media/base/audio_bus.h"
 #include "media/base/media_export.h"
 
 namespace media {
@@ -22,14 +23,9 @@ class AudioRendererSink
  public:
   class RenderCallback {
    public:
-    // Fills entire buffer of length |number_of_frames| but returns actual
-    // number of frames it got from its source (|number_of_frames| in case of
-    // continuous stream). That actual number of frames is passed to host
-    // together with PCM audio data and host is free to use or ignore it.
-    // TODO(crogers): use base:Callback instead.
-    virtual int Render(const std::vector<float*>& audio_data,
-                       int number_of_frames,
-                       int audio_delay_milliseconds) = 0;
+    // Attempts to completely fill all channels of |audio_bus|, returns actual
+    // number of frames filled.
+    virtual int Render(AudioBus* audio_bus, int audio_delay_milliseconds) = 0;
 
     // Signals an error has occurred.
     virtual void OnRenderError() = 0;
diff --git a/media/base/fake_audio_render_callback.cc b/media/base/fake_audio_render_callback.cc
index 15986fd..6adf569 100644
--- a/media/base/fake_audio_render_callback.cc
+++ b/media/base/fake_audio_render_callback.cc
@@ -19,21 +19,21 @@ FakeAudioRenderCallback::FakeAudioRenderCallback(double step)
 
 FakeAudioRenderCallback::~FakeAudioRenderCallback() {}
 
-int FakeAudioRenderCallback::Render(const std::vector<float*>& audio_data,
-                                    int number_of_frames,
+int FakeAudioRenderCallback::Render(AudioBus* audio_bus,
                                     int audio_delay_milliseconds) {
+  int number_of_frames = audio_bus->frames();
   if (half_fill_)
     number_of_frames /= 2;
 
   // Fill first channel with a sine wave.
   for (int i = 0; i < number_of_frames; ++i)
-    audio_data[0][i] = sin(2 * M_PI * (x_ + step_ * i));
+    audio_bus->channel(0)[i] = sin(2 * M_PI * (x_ + step_ * i));
   x_ += number_of_frames * step_;
 
   // Copy first channel into the rest of the channels.
-  for (size_t i = 1; i < audio_data.size(); ++i)
-    memcpy(audio_data[i], audio_data[0],
-           number_of_frames * sizeof(*audio_data[0]));
+  for (int i = 1; i < audio_bus->channels(); ++i)
+    memcpy(audio_bus->channel(i), audio_bus->channel(0),
+           number_of_frames * sizeof(*audio_bus->channel(i)));
 
   return number_of_frames;
 }
diff --git a/media/base/fake_audio_render_callback.h b/media/base/fake_audio_render_callback.h
index b1a4e44..f6ce104 100644
--- a/media/base/fake_audio_render_callback.h
+++ b/media/base/fake_audio_render_callback.h
@@ -5,8 +5,6 @@
 #ifndef MEDIA_BASE_FAKE_AUDIO_RENDER_CALLBACK_H_
 #define MEDIA_BASE_FAKE_AUDIO_RENDER_CALLBACK_H_
 
-#include <vector>
-
 #include "media/base/audio_renderer_sink.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -24,8 +22,7 @@ class FakeAudioRenderCallback : public AudioRendererSink::RenderCallback {
 
   // Renders a sine wave into the provided audio data buffer.  If |half_fill_|
   // is set, will only fill half the buffer.
-  int Render(const std::vector<float*>& audio_data, int number_of_frames,
-             int audio_delay_milliseconds) OVERRIDE;
+  int Render(AudioBus* audio_bus, int audio_delay_milliseconds) OVERRIDE;
   MOCK_METHOD0(OnRenderError, void());
 
   // Toggles only filling half the requested amount during Render().
diff --git a/media/base/multi_channel_resampler.cc b/media/base/multi_channel_resampler.cc
index 23ab0eb..960a212 100644
--- a/media/base/multi_channel_resampler.cc
+++ b/media/base/multi_channel_resampler.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
+#include "media/base/audio_bus.h"
 
 namespace media {
 
@@ -14,7 +15,6 @@ MultiChannelResampler::MultiChannelResampler(int channels,
                                              double io_sample_rate_ratio,
                                              const ReadCB& read_cb)
     : last_frame_count_(0),
-      first_frame_count_(0),
       read_cb_(read_cb) {
   // Allocate each channel's resampler.
   resamplers_.reserve(channels);
@@ -24,17 +24,10 @@ MultiChannelResampler::MultiChannelResampler(int channels,
   }
 }
 
-MultiChannelResampler::~MultiChannelResampler() {
-  // Clean up |resampler_audio_data_|.  Skip the first channel since we never
-  // allocated that, but just used the destination passed into ProvideInput().
-  for (size_t i = 1; i < resampler_audio_data_.size(); ++i)
-    delete [] resampler_audio_data_[i];
-  resampler_audio_data_.clear();
-}
+MultiChannelResampler::~MultiChannelResampler() {}
 
-void MultiChannelResampler::Resample(const std::vector<float*>& destination,
-                                     int frames) {
-  DCHECK_EQ(destination.size(), resamplers_.size());
+void MultiChannelResampler::Resample(AudioBus* audio_bus, int frames) {
+  DCHECK_EQ(static_cast<size_t>(audio_bus->channels()), resamplers_.size());
 
   // We need to ensure that SincResampler only calls ProvideInput once for each
   // channel.  To ensure this, we chunk the number of requested frames into
@@ -55,7 +48,8 @@ void MultiChannelResampler::Resample(const std::vector<float*>& destination,
       // the first channel, then it will call it for the remaining channels,
       // since they all buffer in the same way and are processing the same
       // number of frames.
-      resamplers_[i]->Resample(destination[i] + frames_done, frames_this_time);
+      resamplers_[i]->Resample(
+          audio_bus->channel(i) + frames_done, frames_this_time);
     }
 
     frames_done += frames_this_time;
@@ -66,32 +60,37 @@ void MultiChannelResampler::ProvideInput(int channel, float* destination,
                                          int frames) {
   // Get the data from the multi-channel provider when the first channel asks
   // for it.  For subsequent channels, we can just dish out the channel data
-  // from that (stored in |resampler_audio_data_|).
+  // from that (stored in |resampler_audio_bus_|).
   if (channel == 0) {
-    // Allocate staging arrays on the first request.
-    if (resampler_audio_data_.size() == 0) {
-      first_frame_count_ = frames;
-      // Skip allocation of the first buffer, since we'll use |destination|
-      // directly for that.
-      resampler_audio_data_.reserve(resamplers_.size());
+    // Allocate staging arrays on the first request and if the frame size or
+    // |destination| changes (should only happen once).
+    if (!resampler_audio_bus_.get() ||
+        resampler_audio_bus_->frames() != frames ||
+        wrapped_resampler_audio_bus_->channel(0) != destination) {
+      resampler_audio_bus_ = AudioBus::Create(resamplers_.size(), frames);
+
+      // Create a channel vector based on |resampler_audio_bus_| but using
+      // |destination| directly for the first channel and then wrap it in a new
+      // AudioBus so we can avoid an extra memcpy later.
+      resampler_audio_data_.clear();
+      resampler_audio_data_.reserve(resampler_audio_bus_->channels());
       resampler_audio_data_.push_back(destination);
-      for (size_t i = 1; i < resamplers_.size(); ++i)
-        resampler_audio_data_.push_back(new float[frames]);
-    } else {
-      DCHECK_LE(frames, first_frame_count_);
-      resampler_audio_data_[0] = destination;
+      for (int i = 1; i < resampler_audio_bus_->channels(); ++i)
+        resampler_audio_data_.push_back(resampler_audio_bus_->channel(i));
+      wrapped_resampler_audio_bus_ = AudioBus::WrapVector(
+          frames, resampler_audio_data_);
     }
 
     last_frame_count_ = frames;
-    read_cb_.Run(resampler_audio_data_, frames);
+    read_cb_.Run(wrapped_resampler_audio_bus_.get());
   } else {
     // All channels must ask for the same amount.  This should always be the
     // case, but let's just make sure.
     DCHECK_EQ(frames, last_frame_count_);
 
     // Copy the channel data from what we received from |read_cb_|.
-    memcpy(destination, resampler_audio_data_[channel],
-           sizeof(*resampler_audio_data_[channel]) * frames);
+    memcpy(destination, resampler_audio_bus_->channel(channel),
+           sizeof(*resampler_audio_bus_->channel(channel)) * frames);
   }
 }
 
diff --git a/media/base/multi_channel_resampler.h b/media/base/multi_channel_resampler.h
index db95bc5..6d65075 100644
--- a/media/base/multi_channel_resampler.h
+++ b/media/base/multi_channel_resampler.h
@@ -13,16 +13,16 @@
 #include "media/base/sinc_resampler.h"
 
 namespace media {
+class AudioBus;
 
 // MultiChannelResampler is a multi channel wrapper for SincResampler; allowing
 // high quality sample rate conversion of multiple channels at once.
 class MEDIA_EXPORT MultiChannelResampler {
  public:
-  // Callback type for providing more data into the resampler.  Expects |frames|
-  // of data for all channels to be rendered into |destination|; zero padded if
-  // not enough frames are available to satisfy the request.
-  typedef base::Callback<void(const std::vector<float*>& destination,
-                              int frames)> ReadCB;
+  // Callback type for providing more data into the resampler.  Expects AudioBus
+  // to be completely filled with data upon return; zero padded if not enough
+  // frames are available to satisfy the request.
+  typedef base::Callback<void(AudioBus* audio_bus)> ReadCB;
 
   // Constructs a MultiChannelResampler with the specified |read_cb|, which is
   // used to acquire audio data for resampling.  |io_sample_rate_ratio| is the
@@ -31,8 +31,8 @@ class MEDIA_EXPORT MultiChannelResampler {
                         const ReadCB& read_cb);
   virtual ~MultiChannelResampler();
 
-  // Resample |frames| of data from |read_cb_| into |destination|.
-  void Resample(const std::vector<float*>& destination, int frames);
+  // Resamples |frames| of data from |read_cb_| into AudioBus.
+  void Resample(AudioBus* audio_bus, int frames);
 
  private:
   // SincResampler::ReadCB implementation.  ProvideInput() will be called for
@@ -43,17 +43,15 @@ class MEDIA_EXPORT MultiChannelResampler {
   // frames for every channel.
   int last_frame_count_;
 
-  // Sanity check to ensure |resampler_audio_data_| is properly allocated.
-  int first_frame_count_;
-
   // Source of data for resampling.
   ReadCB read_cb_;
 
   // Each channel has its own high quality resampler.
   ScopedVector<SincResampler> resamplers_;
 
-  // Buffer for audio data going into SincResampler from ReadCB.  Owned by this
-  // class and only temporarily passed out to ReadCB when data is required.
+  // Buffers for audio data going into SincResampler from ReadCB.
+  scoped_ptr<AudioBus> resampler_audio_bus_;
+  scoped_ptr<AudioBus> wrapped_resampler_audio_bus_;
   std::vector<float*> resampler_audio_data_;
 };
 
diff --git a/media/base/multi_channel_resampler_unittest.cc b/media/base/multi_channel_resampler_unittest.cc
index 0475d76..d32396e 100644
--- a/media/base/multi_channel_resampler_unittest.cc
+++ b/media/base/multi_channel_resampler_unittest.cc
@@ -8,6 +8,7 @@
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "media/base/audio_bus.h"
 #include "media/base/multi_channel_resampler.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -37,33 +38,20 @@ class MultiChannelResamplerTest
     : public testing::TestWithParam<int> {
  public:
   MultiChannelResamplerTest() {}
-  virtual ~MultiChannelResamplerTest() {
-    if (!audio_data_.empty()) {
-      for (size_t i = 0; i < audio_data_.size(); ++i)
-        delete [] audio_data_[i];
-      audio_data_.clear();
-    }
-  }
+  virtual ~MultiChannelResamplerTest() {}
 
   void InitializeAudioData(int channels, int frames) {
     frames_ = frames;
-    audio_data_.reserve(channels);
-    for (int i = 0; i < channels; ++i) {
-      audio_data_.push_back(new float[frames]);
-
-      // Zero initialize so we can be sure every value has been provided.
-      memset(audio_data_[i], 0, sizeof(*audio_data_[i]) * frames);
-    }
+    audio_bus_ = AudioBus::Create(channels, frames);
   }
 
   // MultiChannelResampler::MultiChannelAudioSourceProvider implementation, just
   // fills the provided audio_data with |kFillValue|.
-  virtual void ProvideInput(const std::vector<float*>& audio_data,
-                            int number_of_frames) {
-    EXPECT_EQ(audio_data.size(), audio_data_.size());
-    for (size_t i = 0; i < audio_data.size(); ++i)
-      for (int j = 0; j < number_of_frames; ++j)
-        audio_data[i][j] = kFillValue;
+  virtual void ProvideInput(AudioBus* audio_bus) {
+    EXPECT_EQ(audio_bus->channels(), audio_bus_->channels());
+    for (int i = 0; i < audio_bus->channels(); ++i)
+      for (int j = 0; j < audio_bus->frames(); ++j)
+        audio_bus->channel(i)[j] = kFillValue;
   }
 
   void MultiChannelTest(int channels, int frames, double expected_max_rms_error,
@@ -73,7 +61,7 @@ class MultiChannelResamplerTest
         channels, kScaleFactor, base::Bind(
             &MultiChannelResamplerTest::ProvideInput,
             base::Unretained(this)));
-    resampler.Resample(audio_data_, frames);
+    resampler.Resample(audio_bus_.get(), frames);
     TestValues(expected_max_rms_error, expected_max_error);
   }
 
@@ -91,19 +79,19 @@ class MultiChannelResamplerTest
     // Calculate Root-Mean-Square-Error for the resampling.
     double max_error = 0.0;
     double sum_of_squares = 0.0;
-    for (size_t i = 0; i < audio_data_.size(); ++i) {
+    for (int i = 0; i < audio_bus_->channels(); ++i) {
       for (int j = 0; j < frames_; ++j) {
         // Ensure all values are accounted for.
-        ASSERT_NE(audio_data_[i][j], 0);
+        ASSERT_NE(audio_bus_->channel(i)[j], 0);
 
-        double error = fabs(audio_data_[i][j] - kFillValue);
+        double error = fabs(audio_bus_->channel(i)[j] - kFillValue);
         max_error = std::max(max_error, error);
         sum_of_squares += error * error;
       }
     }
 
     double rms_error = sqrt(
-        sum_of_squares / (frames_ * audio_data_.size()));
+        sum_of_squares / (frames_ * audio_bus_->channels()));
 
     EXPECT_LE(rms_error, expected_max_rms_error);
     EXPECT_LE(max_error, expected_max_error);
@@ -111,7 +99,7 @@ class MultiChannelResamplerTest
 
  protected:
   int frames_;
-  std::vector<float*> audio_data_;
+  scoped_ptr<AudioBus> audio_bus_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiChannelResamplerTest);
 };
diff --git a/media/base/sinc_resampler.h b/media/base/sinc_resampler.h
index 4c55eab..029a38a 100644
--- a/media/base/sinc_resampler.h
+++ b/media/base/sinc_resampler.h
@@ -81,6 +81,8 @@ class MEDIA_EXPORT SincResampler {
   float* const r3_;
   float* const r4_;
   float* const r5_;
+
+  DISALLOW_COPY_AND_ASSIGN(SincResampler);
 };
 
 }  // namespace media
diff --git a/media/filters/audio_renderer_impl.cc b/media/filters/audio_renderer_impl.cc
index 50bf16c..384935e 100644
--- a/media/filters/audio_renderer_impl.cc
+++ b/media/filters/audio_renderer_impl.cc
@@ -325,13 +325,11 @@ bool AudioRendererImpl::IsBeforePrerollTime(
       (buffer->GetTimestamp() + buffer->GetDuration()) < preroll_timestamp_;
 }
 
-int AudioRendererImpl::Render(const std::vector<float*>& audio_data,
-                              int number_of_frames,
+int AudioRendererImpl::Render(AudioBus* audio_bus,
                               int audio_delay_milliseconds) {
   if (stopped_ || GetPlaybackRate() == 0.0f) {
     // Output silence if stopped.
-    for (size_t i = 0; i < audio_data.size(); ++i)
-      memset(audio_data[i], 0, sizeof(float) * number_of_frames);
+    audio_bus->Zero();
     return 0;
   }
 
@@ -348,30 +346,29 @@ int AudioRendererImpl::Render(const std::vector<float*>& audio_data,
 
   int bytes_per_frame = audio_parameters_.GetBytesPerFrame();
 
-  const int buf_size = number_of_frames * bytes_per_frame;
+  const int buf_size = audio_bus->frames() * bytes_per_frame;
   scoped_array<uint8> buf(new uint8[buf_size]);
 
-  int frames_filled = FillBuffer(buf.get(), number_of_frames, request_delay);
+  int frames_filled = FillBuffer(buf.get(), audio_bus->frames(), request_delay);
   int bytes_filled = frames_filled * bytes_per_frame;
   DCHECK_LE(bytes_filled, buf_size);
   UpdateEarliestEndTime(bytes_filled, request_delay, base::Time::Now());
 
   // Deinterleave each audio channel.
-  int channels = audio_data.size();
+  int channels = audio_bus->channels();
   for (int channel_index = 0; channel_index < channels; ++channel_index) {
     media::DeinterleaveAudioChannel(buf.get(),
-                                    audio_data[channel_index],
+                                    audio_bus->channel(channel_index),
                                     channels,
                                     channel_index,
                                     bytes_per_frame / channels,
                                     frames_filled);
 
     // If FillBuffer() didn't give us enough data then zero out the remainder.
-    if (frames_filled < number_of_frames) {
-      int frames_to_zero = number_of_frames - frames_filled;
-      memset(audio_data[channel_index] + frames_filled,
-             0,
-             sizeof(float) * frames_to_zero);
+    if (frames_filled < audio_bus->frames()) {
+      int frames_to_zero = audio_bus->frames() - frames_filled;
+      memset(audio_bus->channel(channel_index) + frames_filled, 0,
+             sizeof(*audio_bus->channel(channel_index)) * frames_to_zero);
     }
   }
   return frames_filled;
diff --git a/media/filters/audio_renderer_impl.h b/media/filters/audio_renderer_impl.h
index f6c72f9..68f3250 100644
--- a/media/filters/audio_renderer_impl.h
+++ b/media/filters/audio_renderer_impl.h
@@ -119,8 +119,7 @@ class MEDIA_EXPORT AudioRendererImpl
   void DoPause();
 
   // media::AudioRendererSink::RenderCallback implementation.
-  virtual int Render(const std::vector<float*>& audio_data,
-                     int number_of_frames,
+  virtual int Render(AudioBus* audio_bus,
                      int audio_delay_milliseconds) OVERRIDE;
   virtual void OnRenderError() OVERRIDE;