1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
/*
* Copyright (c) 2012 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 "modules/audio_processing/high_pass_filter.h"
#include "api/array_view.h"
#include "modules/audio_processing/audio_buffer.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
// [B,A] = butter(2,100/8000,'high')
constexpr CascadedBiQuadFilter::BiQuadCoefficients
kHighPassFilterCoefficients16kHz = {{0.97261f, -1.94523f, 0.97261f},
{-1.94448f, 0.94598f}};
// [B,A] = butter(2,100/16000,'high')
constexpr CascadedBiQuadFilter::BiQuadCoefficients
kHighPassFilterCoefficients32kHz = {{0.98621f, -1.97242f, 0.98621f},
{-1.97223f, 0.97261f}};
// [B,A] = butter(2,100/24000,'high')
constexpr CascadedBiQuadFilter::BiQuadCoefficients
kHighPassFilterCoefficients48kHz = {{0.99079f, -1.98157f, 0.99079f},
{-1.98149f, 0.98166f}};
constexpr size_t kNumberOfHighPassBiQuads = 1;
const CascadedBiQuadFilter::BiQuadCoefficients& ChooseCoefficients(
int sample_rate_hz) {
switch (sample_rate_hz) {
case 16000:
return kHighPassFilterCoefficients16kHz;
case 32000:
return kHighPassFilterCoefficients32kHz;
case 48000:
return kHighPassFilterCoefficients48kHz;
default:
RTC_DCHECK_NOTREACHED();
}
RTC_DCHECK_NOTREACHED();
return kHighPassFilterCoefficients16kHz;
}
} // namespace
HighPassFilter::HighPassFilter(int sample_rate_hz, size_t num_channels)
: sample_rate_hz_(sample_rate_hz) {
filters_.resize(num_channels);
const auto& coefficients = ChooseCoefficients(sample_rate_hz_);
for (size_t k = 0; k < filters_.size(); ++k) {
filters_[k].reset(
new CascadedBiQuadFilter(coefficients, kNumberOfHighPassBiQuads));
}
}
HighPassFilter::~HighPassFilter() = default;
void HighPassFilter::Process(AudioBuffer* audio, bool use_split_band_data) {
RTC_DCHECK(audio);
RTC_DCHECK_EQ(filters_.size(), audio->num_channels());
if (use_split_band_data) {
for (size_t k = 0; k < audio->num_channels(); ++k) {
rtc::ArrayView<float> channel_data = rtc::ArrayView<float>(
audio->split_bands(k)[0], audio->num_frames_per_band());
filters_[k]->Process(channel_data);
}
} else {
for (size_t k = 0; k < audio->num_channels(); ++k) {
rtc::ArrayView<float> channel_data =
rtc::ArrayView<float>(&audio->channels()[k][0], audio->num_frames());
filters_[k]->Process(channel_data);
}
}
}
void HighPassFilter::Process(std::vector<std::vector<float>>* audio) {
RTC_DCHECK_EQ(filters_.size(), audio->size());
for (size_t k = 0; k < audio->size(); ++k) {
filters_[k]->Process((*audio)[k]);
}
}
void HighPassFilter::Reset() {
for (size_t k = 0; k < filters_.size(); ++k) {
filters_[k]->Reset();
}
}
void HighPassFilter::Reset(size_t num_channels) {
const size_t old_num_channels = filters_.size();
filters_.resize(num_channels);
if (filters_.size() < old_num_channels) {
Reset();
} else {
for (size_t k = 0; k < old_num_channels; ++k) {
filters_[k]->Reset();
}
const auto& coefficients = ChooseCoefficients(sample_rate_hz_);
for (size_t k = old_num_channels; k < filters_.size(); ++k) {
filters_[k].reset(
new CascadedBiQuadFilter(coefficients, kNumberOfHighPassBiQuads));
}
}
}
} // namespace webrtc
|
