Added basic framework for AEC3 in the audio processing module

webrtc/modules/audio_processing/aec3/echo_canceller3.h

Index: webrtc/modules/audio_processing/aec3/echo_canceller3.h
diff --git a/webrtc/modules/audio_processing/aec3/echo_canceller3.h b/webrtc/modules/audio_processing/aec3/echo_canceller3.h
new file mode 100644
index 0000000000000000000000000000000000000000..b5a2e64c4db3b0dbd94ac962d88e88f58efa7a08
--- /dev/null
+++ b/webrtc/modules/audio_processing/aec3/echo_canceller3.h
@@ -0,0 +1,43 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_CANCELLER3_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_CANCELLER3_H_
+
+#include <string>
+
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/modules/audio_processing/audio_buffer.h"
+
+namespace webrtc {
+
+class EchoCanceller3 {
+ public:
+  EchoCanceller3(int sample_rate_hz, bool use_anti_hum_filter);
+  ~EchoCanceller3();
+  bool AnalyzeRender(AudioBuffer* farend) const;
+  void AnalyzeCapture(AudioBuffer* capture);

[ivoc, 2016/12/09 14:11:09]

Why does AEC3 have both AnalyzeCapture and ProcessCapture? Isn't ProcessCapture
enough?

[peah-webrtc, 2016/12/12 19:46:45]

Both are needed as the capture signal needs to be analyzed before the
band-splitting (in order to properly detect signal saturation) and processed
after the band-splitting.

[ivoc, 2016/12/14 08:54:15]

Acknowledged.

+  void ProcessCapture(AudioBuffer* capture, bool known_echo_path_change);
+
+  // Validates a config.
+  static bool Validate(const AudioProcessing::Config::EchoCanceller3& config);
+  // Dumps a config to a string.
+  static std::string ToString(
+      const AudioProcessing::Config::EchoCanceller3& config);
+
+ private:
+  static int instance_count_;
+  size_t frame_length_;
+
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(EchoCanceller3);
+};
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_ECHO_CANCELLER3_H_