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
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/audio/stereo_panner.h"
#include <algorithm>
#include <memory>
#include "base/memory/ptr_util.h"
#include "third_party/blink/renderer/platform/audio/audio_bus.h"
#include "third_party/blink/renderer/platform/audio/audio_utilities.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
#include "third_party/fdlibm/ieee754.h"
namespace blink {
// Implement equal-power panning algorithm for mono or stereo input.
// See: http://webaudio.github.io/web-audio-api/#panning-algorithm
StereoPanner::StereoPanner(float sample_rate) {}
void StereoPanner::PanWithSampleAccurateValues(const AudioBus* input_bus,
AudioBus* output_bus,
const float* pan_values,
uint32_t frames_to_process) {
DCHECK(input_bus);
DCHECK_LE(frames_to_process, input_bus->length());
DCHECK_GE(input_bus->NumberOfChannels(), 1u);
DCHECK_LE(input_bus->NumberOfChannels(), 2u);
unsigned number_of_input_channels = input_bus->NumberOfChannels();
DCHECK(output_bus);
DCHECK_EQ(output_bus->NumberOfChannels(), 2u);
DCHECK_LE(frames_to_process, output_bus->length());
const float* source_l = input_bus->Channel(0)->Data();
const float* source_r =
number_of_input_channels > 1 ? input_bus->Channel(1)->Data() : source_l;
float* destination_l =
output_bus->ChannelByType(AudioBus::kChannelLeft)->MutableData();
float* destination_r =
output_bus->ChannelByType(AudioBus::kChannelRight)->MutableData();
if (!source_l || !source_r || !destination_l || !destination_r)
return;
double gain_l, gain_r, pan_radian;
int n = frames_to_process;
if (number_of_input_channels == 1) { // For mono source case.
while (n--) {
float input_l = *source_l++;
double pan = clampTo(*pan_values++, -1.0, 1.0);
// Pan from left to right [-1; 1] will be normalized as [0; 1].
pan_radian = (pan * 0.5 + 0.5) * kPiOverTwoDouble;
gain_l = fdlibm::cos(pan_radian);
gain_r = fdlibm::sin(pan_radian);
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_l * gain_r);
}
} else { // For stereo source case.
while (n--) {
float input_l = *source_l++;
float input_r = *source_r++;
double pan = clampTo(*pan_values++, -1.0, 1.0);
// Normalize [-1; 0] to [0; 1]. Do nothing when [0; 1].
pan_radian = (pan <= 0 ? pan + 1 : pan) * kPiOverTwoDouble;
gain_l = fdlibm::cos(pan_radian);
gain_r = fdlibm::sin(pan_radian);
if (pan <= 0) {
*destination_l++ = static_cast<float>(input_l + input_r * gain_l);
*destination_r++ = static_cast<float>(input_r * gain_r);
} else {
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_r + input_l * gain_r);
}
}
}
}
void StereoPanner::PanToTargetValue(const AudioBus* input_bus,
AudioBus* output_bus,
float pan_value,
uint32_t frames_to_process) {
DCHECK(input_bus);
DCHECK_LE(frames_to_process, input_bus->length());
DCHECK_GE(input_bus->NumberOfChannels(), 1u);
DCHECK_LE(input_bus->NumberOfChannels(), 2u);
unsigned number_of_input_channels = input_bus->NumberOfChannels();
DCHECK(output_bus);
DCHECK_EQ(output_bus->NumberOfChannels(), 2u);
DCHECK_LE(frames_to_process, output_bus->length());
const float* source_l = input_bus->Channel(0)->Data();
const float* source_r =
number_of_input_channels > 1 ? input_bus->Channel(1)->Data() : source_l;
float* destination_l =
output_bus->ChannelByType(AudioBus::kChannelLeft)->MutableData();
float* destination_r =
output_bus->ChannelByType(AudioBus::kChannelRight)->MutableData();
if (!source_l || !source_r || !destination_l || !destination_r)
return;
float target_pan = clampTo(pan_value, -1.0, 1.0);
int n = frames_to_process;
if (number_of_input_channels == 1) { // For mono source case.
// Pan from left to right [-1; 1] will be normalized as [0; 1].
double pan_radian = (target_pan * 0.5 + 0.5) * kPiOverTwoDouble;
double gain_l = fdlibm::cos(pan_radian);
double gain_r = fdlibm::sin(pan_radian);
// TODO(rtoy): This can be vectorized using vector_math::Vsmul
while (n--) {
float input_l = *source_l++;
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_l * gain_r);
}
} else { // For stereo source case.
// Normalize [-1; 0] to [0; 1] for the left pan position (<= 0), and
// do nothing when [0; 1].
double pan_radian =
(target_pan <= 0 ? target_pan + 1 : target_pan) * kPiOverTwoDouble;
double gain_l = fdlibm::cos(pan_radian);
double gain_r = fdlibm::sin(pan_radian);
// TODO(rtoy): Consider moving the if statement outside the loop
// since |target_pan| is constant inside the loop.
while (n--) {
float input_l = *source_l++;
float input_r = *source_r++;
if (target_pan <= 0) {
// When [-1; 0], keep left channel intact and equal-power pan the
// right channel only.
*destination_l++ = static_cast<float>(input_l + input_r * gain_l);
*destination_r++ = static_cast<float>(input_r * gain_r);
} else {
// When [0; 1], keep right channel intact and equal-power pan the
// left channel only.
*destination_l++ = static_cast<float>(input_l * gain_l);
*destination_r++ = static_cast<float>(input_r + input_l * gain_r);
}
}
}
}
} // namespace blink
|
