1
2 /*
3 * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
4 *
5 * Use of this source code is governed by a BSD-style license
6 * that can be found in the LICENSE file in the root of the source
7 * tree. An additional intellectual property rights grant can be found
8 * in the file PATENTS. All contributing project authors may
9 * be found in the AUTHORS file in the root of the source tree.
10 */
11
12 #include "modules/audio_processing/aec3/moving_average.h"
13
14 #include <algorithm>
15 #include <functional>
16
17 #include "rtc_base/checks.h"
18
19 namespace webrtc {
20 namespace aec3 {
21
MovingAverage(size_t num_elem,size_t mem_len)22 MovingAverage::MovingAverage(size_t num_elem, size_t mem_len)
23 : num_elem_(num_elem),
24 mem_len_(mem_len - 1),
25 scaling_(1.0f / static_cast<float>(mem_len)),
26 memory_(num_elem * mem_len_, 0.f),
27 mem_index_(0) {
28 RTC_DCHECK(num_elem_ > 0);
29 RTC_DCHECK(mem_len > 0);
30 }
31
32 MovingAverage::~MovingAverage() = default;
33
Average(rtc::ArrayView<const float> input,rtc::ArrayView<float> output)34 void MovingAverage::Average(rtc::ArrayView<const float> input,
35 rtc::ArrayView<float> output) {
36 RTC_DCHECK(input.size() == num_elem_);
37 RTC_DCHECK(output.size() == num_elem_);
38
39 // Sum all contributions.
40 std::copy(input.begin(), input.end(), output.begin());
41 for (auto i = memory_.begin(); i < memory_.end(); i += num_elem_) {
42 std::transform(i, i + num_elem_, output.begin(), output.begin(),
43 std::plus<float>());
44 }
45
46 // Divide by mem_len_.
47 for (float& o : output) {
48 o *= scaling_;
49 }
50
51 // Update memory.
52 if (mem_len_ > 0) {
53 std::copy(input.begin(), input.end(),
54 memory_.begin() + mem_index_ * num_elem_);
55 mem_index_ = (mem_index_ + 1) % mem_len_;
56 }
57 }
58
59 } // namespace aec3
60 } // namespace webrtc
61