Finalization of the first version of EchoCanceller 3

webrtc/modules/audio_processing/aec3/delay_handler.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/delay_handler.h"
+
+#include "webrtc/base/checks.h"
+#include "webrtc/modules/audio_processing/aec3/aec3_constants.h"
+
+namespace webrtc {
+namespace {
+
+// Compute the delay of the adaptive filter as the partition with a distinct
+// peak.
+rtc::Optional<size_t> IdentifyFilterDelay(
+    const std::vector<std::array<float, kFftLengthBy2Plus1>>&
+        filter_frequency_response) {
+  const std::vector<std::array<float, kFftLengthBy2Plus1>>& H2 =

[ivoc, 2017/02/10 13:52:34]

I would prefer const auto& here.

[peah-webrtc, 2017/02/20 07:37:15]

Done.

+      filter_frequency_response;
+
+  size_t reliable_delays_sum = 0;
+  size_t num_reliable_delays = 0;
+
+  for (size_t k = 1; k < kFftLengthBy2 - 5; ++k) {

[ivoc, 2017/02/10 13:52:34]

Why is the "- 5" here?

[peah-webrtc, 2017/02/20 07:37:15]

The intention is that there is no point computing this for upper frequencies due
to the anti-aliasing filter. I changed it into a constant.

+    int peak = 0;
+    for (size_t j = 0; j < H2.size(); ++j) {
+      if (H2[j][k] > H2[peak][k]) {
+        peak = j;
+      }
+    }
+
+    if (5 * H2[H2.size() - 1][k] < H2[peak][k]) {

[ivoc, 2017/02/10 13:52:34]

Please define the 5 as a constexpr.

[peah-webrtc, 2017/02/20 07:37:15]

Done.

+      reliable_delays_sum += peak;
+      ++num_reliable_delays;
+    }
+  }
+
+  return num_reliable_delays > 5

[ivoc, 2017/02/10 13:52:34]

This 5 as well.

[peah-webrtc, 2017/02/20 07:37:15]

Done.

+             ? rtc::Optional<size_t>(reliable_delays_sum / num_reliable_delays)
+             : rtc::Optional<size_t>();
+}
+
+}  // namespace
+
+DelayHandler::DelayHandler() = default;
+
+DelayHandler::~DelayHandler() = default;
+
+void DelayHandler::UpdateDelays(
+    const std::vector<std::array<float, kFftLengthBy2Plus1>>&
+        filter_frequency_response,
+    const rtc::Optional<size_t>& external_delay_samples) {
+  filter_delay_ = IdentifyFilterDelay(filter_frequency_response);
+
+  // Compute the externally provided delay in partitions. The truncation is
+  // intended here.
+  external_delay_ =
+      external_delay_samples
+          ? rtc::Optional<size_t>(*external_delay_samples / kBlockSize)
+          : rtc::Optional<size_t>();
+}
+
+}  // namespace webrtc