Collapse AudioRendererMixer and OnMoreDataResampler into AudioTransform.

Currently we have roughly equivalent functionality in two places, and
the CloudView project will add a third.  As such there's a need for a
single super class which can handle mixing, resampling, and general
conversion from one set of AudioParameters to another.

This change introduces the AudioTransform object which collapses the
key functionality from AudioRendererMixer and OnMoreDataResampler into
a single AudioTransform class which can do everything and is oblivious
to the peculiars of RenderCallback vs AudioSourceCallback.

It also introduces output_frames_ready() methods to the AudioPullFifo
and MultiChannelResampler classes so that buffer delay can be measured
accurately without resorting to input vs output byte counting. 

Due to the bulk of AudioRendererMixer's functionality moving into the
new AudioTransform, it made sense to move some decisions into the
AudioRendererMixerInput class as well.

On my Z600, benchmarking 50000 iterations:
Convert() w/ FIFO took 7030.11ms.
Convert() w/o FIFO took 5218.83ms.

BUG=none
TEST=AudioTransform* unittests.
TBR=sergeyu

Review URL: https://chromiumcodereview.appspot.com/11410012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@168976 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 81 deletions

diff --git a/media/base/audio_renderer_mixer.cc b/media/base/audio_renderer_mixer.cc
index 4df2eea..003f6dd 100644
--- a/media/base/audio_renderer_mixer.cc
+++ b/media/base/audio_renderer_mixer.cc
@@ -7,9 +7,6 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
-#include "media/audio/audio_util.h"
-#include "media/base/limits.h"
-#include "media/base/vector_math.h"
 
 namespace media {
 
@@ -17,26 +14,7 @@ AudioRendererMixer::AudioRendererMixer(
     const AudioParameters& input_params, const AudioParameters& output_params,
     const scoped_refptr<AudioRendererSink>& sink)
     : audio_sink_(sink),
-      current_audio_delay_milliseconds_(0),
-      io_ratio_(1),
-      input_ms_per_frame_(
-          static_cast<double>(base::Time::kMillisecondsPerSecond) /
-          input_params.sample_rate()) {
-  DCHECK(input_params.IsValid());
-  DCHECK(output_params.IsValid());
-
-  // Channel mixing is handled by the browser side currently.
-  DCHECK_EQ(input_params.channels(), output_params.channels());
-
-  // Only resample if necessary since it's expensive.
-  if (input_params.sample_rate() != output_params.sample_rate()) {
-    io_ratio_ = input_params.sample_rate() /
-        static_cast<double>(output_params.sample_rate());
-    resampler_.reset(new MultiChannelResampler(
-        output_params.channels(), io_ratio_,
-        base::Bind(&AudioRendererMixer::ProvideInput, base::Unretained(this))));
-  }
-
+      audio_converter_(input_params, output_params, true) {
   audio_sink_->Initialize(output_params, this);
   audio_sink_->Start();
 }
@@ -53,78 +31,29 @@ AudioRendererMixer::~AudioRendererMixer() {
 void AudioRendererMixer::AddMixerInput(
     const scoped_refptr<AudioRendererMixerInput>& input) {
   base::AutoLock auto_lock(mixer_inputs_lock_);
-  mixer_inputs_.insert(input);
+  mixer_inputs_.push_back(input);
+  audio_converter_.AddInput(input);
 }
 
 void AudioRendererMixer::RemoveMixerInput(
     const scoped_refptr<AudioRendererMixerInput>& input) {
   base::AutoLock auto_lock(mixer_inputs_lock_);
-  mixer_inputs_.erase(input);
+  audio_converter_.RemoveInput(input);
+  mixer_inputs_.remove(input);
 }
 
 int AudioRendererMixer::Render(AudioBus* audio_bus,
                                int audio_delay_milliseconds) {
-  current_audio_delay_milliseconds_ = audio_delay_milliseconds / io_ratio_;
-
-  if (resampler_.get())
-    resampler_->Resample(audio_bus, audio_bus->frames());
-  else
-    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 audio_bus->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.  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_EQ(audio_bus->frames(), mixer_input_audio_bus_->frames());
-  DCHECK_EQ(audio_bus->channels(), mixer_input_audio_bus_->channels());
-
-  // Zero |audio_bus| so we're mixing into a clean buffer and return silence if
-  // we couldn't get enough data from our inputs.
-  audio_bus->Zero();
-
-  // Have each mixer render its data into an output buffer then mix the result.
+  // Set the delay information for each mixer input.
   for (AudioRendererMixerInputSet::iterator it = mixer_inputs_.begin();
        it != mixer_inputs_.end(); ++it) {
-    const scoped_refptr<AudioRendererMixerInput>& input = *it;
-
-    double volume;
-    input->GetVolume(&volume);
-
-    // Nothing to do if the input isn't playing.
-    if (!input->playing())
-      continue;
-
-    int frames_filled = input->callback()->Render(
-        mixer_input_audio_bus_.get(), current_audio_delay_milliseconds_);
-    if (frames_filled == 0)
-      continue;
-
-    // Volume adjust and mix each mixer input into |audio_bus| after rendering.
-    for (int i = 0; i < audio_bus->channels(); ++i) {
-      vector_math::FMAC(
-          mixer_input_audio_bus_->channel(i), volume, frames_filled,
-          audio_bus->channel(i));
-    }
+    (*it)->set_audio_delay_milliseconds(audio_delay_milliseconds);
   }
 
-  // Update the delay estimate.
-  current_audio_delay_milliseconds_ +=
-      audio_bus->frames() * input_ms_per_frame_;
+  audio_converter_.Convert(audio_bus);
+  return audio_bus->frames();
 }
 
 void AudioRendererMixer::OnRenderError() {
@@ -133,7 +62,7 @@ void AudioRendererMixer::OnRenderError() {
   // Call each mixer input and signal an error.
   for (AudioRendererMixerInputSet::iterator it = mixer_inputs_.begin();
        it != mixer_inputs_.end(); ++it) {
-    (*it)->callback()->OnRenderError();
+    (*it)->OnRenderError();
   }
 }