Adding full initial version of delay estimation functionality in echo canceller 3

webrtc/modules/audio_processing/aec3/echo_path_delay_estimator.cc

 /*
  *  Copyright (c) 2017 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.
  */
 #include "webrtc/modules/audio_processing/aec3/echo_path_delay_estimator.h"
 
+#include <algorithm>
+#include <array>
+
 #include "webrtc/base/checks.h"
 #include "webrtc/modules/audio_processing/aec3/aec3_constants.h"
+#include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
 
 namespace webrtc {
 
-// TODO(peah): Add functionality.
-EchoPathDelayEstimator::EchoPathDelayEstimator(ApmDataDumper* data_dumper,
-                                               int sample_rate_hz) {
+namespace {
+
+constexpr size_t kNumMatchedFilters = 4;
+constexpr size_t kMatchedFilterWindowSizeSubBlocks = 32;
+constexpr size_t kMatchedFilterAlignmentShiftSizeSubBlocks =
+    kMatchedFilterWindowSizeSubBlocks * 3 / 4;
+
+constexpr int kDownSamplingFactor = 4;
+}  // namespace
+
+EchoPathDelayEstimator::EchoPathDelayEstimator(ApmDataDumper* data_dumper)
+    : data_dumper_(data_dumper),
+      matched_filter_(data_dumper_,
+                      kMatchedFilterWindowSizeSubBlocks,
+                      kNumMatchedFilters,
+                      kMatchedFilterAlignmentShiftSizeSubBlocks),
+      matched_filter_lag_aggregator_(data_dumper_,
+                                     matched_filter_.NumLagEstimates()) {
   RTC_DCHECK(data_dumper);
-  RTC_DCHECK(sample_rate_hz == 8000 || sample_rate_hz == 16000 ||
-             sample_rate_hz == 32000 || sample_rate_hz == 48000);
 }
 
 EchoPathDelayEstimator::~EchoPathDelayEstimator() = default;
 
-// TODO(peah): Add functionality.
 rtc::Optional<size_t> EchoPathDelayEstimator::EstimateDelay(
     rtc::ArrayView<const float> render,
     rtc::ArrayView<const float> capture) {
-  RTC_DCHECK_EQ(render.size(), kBlockSize);
-  RTC_DCHECK_EQ(capture.size(), kBlockSize);
-  return rtc::Optional<size_t>();
+  RTC_DCHECK_EQ(kBlockSize, capture.size());
+  RTC_DCHECK_EQ(render.size(), capture.size());
+
+  std::array<float, kSubBlockSize> downsampled_render;
+  std::array<float, kSubBlockSize> downsampled_capture;
+
+  render_decimator_.Decimate(render, &downsampled_render);
+  capture_decimator_.Decimate(capture, &downsampled_capture);
+
+  matched_filter_.Update(downsampled_render, downsampled_capture);
+
+  rtc::Optional<size_t> aggregated_matched_filter_lag =
+      matched_filter_lag_aggregator_.Aggregate(
+          matched_filter_.GetLagEstimates());
+
+  // TODO(peah): Move this logging outside of this class once EchoCanceller3
+  // development is done.
+  data_dumper_->DumpRaw("aec3_echo_path_delay_estimator_delay",
+                        aggregated_matched_filter_lag
+                            ? static_cast<int>(*aggregated_matched_filter_lag *
+                                               kDownSamplingFactor)
+                            : -1);
+
+  // Return the detected delay in samples as the aggregated matched filter lag
+  // compensated by the down sampling factor for the signal being correlated.
+  return aggregated_matched_filter_lag
+             ? rtc::Optional<size_t>(*aggregated_matched_filter_lag *
+                                     kDownSamplingFactor)
+             : rtc::Optional<size_t>();
 }
 
 }  // namespace webrtc