Add empty residual echo detector.

webrtc/modules/audio_processing/residual_echo_detector.h

+/*
+ *  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_RESIDUAL_ECHO_DETECTOR_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_RESIDUAL_ECHO_DETECTOR_H_
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/swap_queue.h"
+#include "webrtc/modules/audio_processing/include/audio_processing.h"
+#include "webrtc/modules/audio_processing/render_queue_item_verifier.h"
+
+namespace webrtc {
+
+class AudioBuffer;
+class EchoDetector;
+
+class ResidualEchoDetector {
+ public:
+  ResidualEchoDetector();
+  ~ResidualEchoDetector();
+
+  // This function should be called while holding the render lock.
+  // Returns 0 on success and -1 when the render buffer is full. In that case,
+  // ReadQueuedRenderData() should be called before calling this function again.
+  int AnalyzeRenderAudio(const AudioBuffer* audio) const;

[hlundin-webrtc, 2016/10/14 12:36:21]

Make this return true or false instead.

[ivoc, 2016/10/14 14:45:35]

Good idea, done.

+
+  // This function should be called while holding the capture lock.
+  void AnalyzeCaptureAudio(const AudioBuffer* audio);
+
+  // This function should be called while holding the capture lock.
+  void Initialize(int sample_rate_hz);
+
+  // Reads render side data that has been queued on the render call.
+  // This function should be called while holding the capture lock.
+  void ReadQueuedRenderData();
+
+  // This function should be called while holding the capture lock.
+  float get_echo_likelihood() const;
+
+ private:
+  mutable std::vector<float> render_queue_buffer_;
+  std::vector<float> capture_queue_buffer_;
+
+  // Lock protection not needed.
+  mutable std::unique_ptr<
+      SwapQueue<std::vector<float>, RenderQueueItemVerifier<float>>>
+      render_signal_queue_;
+
+  std::unique_ptr<EchoDetector> detector_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_RESIDUAL_ECHO_DETECTOR_H_