Added an "enable-audio-processor" flag and WebRtcAudioProcessor class

content/renderer/media/webrtc_audio_processor.h

Index: content/renderer/media/webrtc_audio_processor.h
diff --git a/content/renderer/media/webrtc_audio_processor.h b/content/renderer/media/webrtc_audio_processor.h
new file mode 100644
index 0000000000000000000000000000000000000000..604cf4e156771cd913db0a86b8e963acfadf8344
--- /dev/null
+++ b/content/renderer/media/webrtc_audio_processor.h
@@ -0,0 +1,135 @@
+// Copyright 2013 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.
+
+#ifndef CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_H_
+#define CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_H_
+
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "content/common/content_export.h"
+#include "media/base/audio_converter.h"
+#include "third_party/libjingle/source/talk/app/webrtc/mediaconstraintsinterface.h"
+#include "third_party/webrtc/modules/audio_processing/include/audio_processing.h"
+#include "third_party/webrtc/modules/interface/module_common_types.h"
+
+namespace media {
+class AudioBus;
+class AudioFifo;
+class AudioParameters;
+}  // namespace media
+
+namespace webrtc {
+class AudioFrame;
+}
+
+namespace content {
+
+// This class owns an object of webrtc::AudioProcessing which contains signal
+// processing components like AGC, AEC and NS. It enables the components based
+// on the constraints, processes the data and outputs it in a unit of 10 ms
+// data chunk.
+class CONTENT_EXPORT WebRtcAudioProcessor {
+ public:
+  explicit WebRtcAudioProcessor(
+      const webrtc::MediaConstraintsInterface* constraints);
+  ~WebRtcAudioProcessor();
+
+  // Pushes capture data in |audio_source| to the internal FIFO.
+  // Called on the capture audio thread.
+  void PushCaptureData(media::AudioBus* audio_source);
+
+  // Processes a block of 10 ms data from the internal FIFO and outputs it via
+  // |out|. |out| is the address of the pointer that will be pointed to
+  // the post-processed data if the method is returning a true.

[Jói, 2013/11/08 16:44:22]

What about ownership? Is the data allocated by this object and ownership passed
to the caller?

[no longer working on chromium, 2013/11/11 14:35:25]

This processor still owns the pointer, |out| just gets a pointer to the data and
the data is guaranteed to outlive the method call.

I added a comment to explain this.

+  // Returns true if the internal FIFO has at least 10ms data for processing,
+  // otherwise false.
+  // Called on the capture audio thread.
+  bool ProcessAndConsumeData(const base::TimeDelta& capture_delay,

[DaleCurtis, 2013/11/08 21:00:48]

base::TimeDelta can be passed by value efficiently instead.  See
base/time/time.h

[no longer working on chromium, 2013/11/11 14:35:25]

Done with passing the value.

+                             int volume,
+                             bool key_pressed,
+                             int16** out);
+
+  // Called when the format of the capture data has changed.
+  // Called on the main render thread.
+  void SetCaptureFormat(const media::AudioParameters& source_params);
+
+  // Push the render audio to WebRtc::AudioProcessing for analysis. This is
+  // needed iff echo processing is enabled.
+  // |render_audio| is the pointer to the render audio data, its format
+  // is specified by |sample_rate|, |number_of_channels| and |number_of_frames|.
+  // Called on the render audio thread.
+  void PushRenderData(const int16* render_audio,
+                      int sample_rate,
+                      int number_of_channels,
+                      int number_of_frames,
+                      const base::TimeDelta& render_delay);
+
+  // The audio format of the output from the processor.
+  const media::AudioParameters& OutputFormat() const;
+
+  // Accessor to check if the audio processing is enabled or not.
+  bool has_audio_processing() const { return audio_processing_.get() != NULL; }
+
+ private:
+  class WebRtcAudioConverter;
+
+  // Helper to initialize the WebRtc AudioProcessing.
+  void InitializeAudioProcessingModule(
+      const webrtc::MediaConstraintsInterface* constraints);
+
+  // Helper to initialize the render converter.
+  void InitializeRenderConverterIfNeeded(int sample_rate,
+                                         int number_of_channels,
+                                         int frames_per_buffer);
+
+  // Called by ProcessAndConsumeData().
+  void ProcessData(webrtc::AudioFrame* audio_frame,
+                   const base::TimeDelta& capture_delay,
+                   int volume,
+                   bool key_pressed);
+
+  // Called when the processor is going away.
+  void StopAudioProcessing();
+
+  // Cached value for the render delay latency.
+  base::TimeDelta render_delay_;
+
+  // Protects |render_delay_|.
+  // TODO(xians): Can we get rid of the lock?
+  mutable base::Lock lock_;
+
+  // WebRtc AudioProcessing module which does AEC, AGC, NS, HighPass filter,
+  // ..etc.
+  scoped_ptr<webrtc::AudioProcessing> audio_processing_;
+
+  // Converter used for the down-mixing and resampling of the capture data.
+  scoped_ptr<WebRtcAudioConverter> capture_converter_;
+
+  // AudioFrame used to hold the output of |capture_converter_|.
+  webrtc::AudioFrame capture_frame_;
+
+  // Converter used for the down-mixing and resampling of the render data when
+  // the AEC is enabled.
+  scoped_ptr<WebRtcAudioConverter> render_converter_;
+
+  // AudioFrame used to hold the output of |render_converter_|.
+  webrtc::AudioFrame render_frame_;
+
+  // Data bus to help converting interleaved data to an AudioBus.
+  scoped_ptr<media::AudioBus> render_data_bus_;
+
+  // Used to DCHECK that some methods are called on the main render thread.
+  base::ThreadChecker main_thread_checker_;
+
+  // Used to DCHECK that some methods are called on the capture audio thread.
+  base::ThreadChecker capture_thread_checker_;
+
+  // Used to DCHECK that PushRenderData() is called on the render audio thread.
+  base::ThreadChecker render_thread_checker_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_WEBRTC_AUDIO_PROCESSOR_H_