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
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/*
* Copyright (C) 2010, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "DelayDSPKernel.h"
#include "AudioUtilities.h"
#include <algorithm>
using namespace std;
namespace WebCore {
const float SmoothingTimeConstant = 0.020f; // 20ms
DelayDSPKernel::DelayDSPKernel(DelayProcessor* processor)
: AudioDSPKernel(processor)
, m_writeIndex(0)
, m_firstTime(true)
, m_delayTimes(AudioNode::ProcessingSizeInFrames)
{
ASSERT(processor && processor->sampleRate() > 0);
if (!(processor && processor->sampleRate() > 0))
return;
m_maxDelayTime = processor->maxDelayTime();
ASSERT(m_maxDelayTime >= 0);
if (m_maxDelayTime < 0)
return;
m_buffer.allocate(bufferLengthForDelay(m_maxDelayTime, processor->sampleRate()));
m_buffer.zero();
m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, processor->sampleRate());
}
DelayDSPKernel::DelayDSPKernel(double maxDelayTime, float sampleRate)
: AudioDSPKernel(sampleRate)
, m_maxDelayTime(maxDelayTime)
, m_writeIndex(0)
, m_firstTime(true)
{
ASSERT(maxDelayTime > 0.0);
if (maxDelayTime <= 0.0)
return;
size_t bufferLength = bufferLengthForDelay(maxDelayTime, sampleRate);
ASSERT(bufferLength);
if (!bufferLength)
return;
m_buffer.allocate(bufferLength);
m_buffer.zero();
m_smoothingRate = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate);
}
size_t DelayDSPKernel::bufferLengthForDelay(double maxDelayTime, double sampleRate) const
{
// Compute the length of the buffer needed to handle a max delay of |maxDelayTime|. One is
// added to handle the case where the actual delay equals the maximum delay.
return 1 + AudioUtilities::timeToSampleFrame(maxDelayTime, sampleRate);
}
void DelayDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
{
size_t bufferLength = m_buffer.size();
float* buffer = m_buffer.data();
ASSERT(bufferLength);
if (!bufferLength)
return;
ASSERT(source && destination);
if (!source || !destination)
return;
float sampleRate = this->sampleRate();
double delayTime = 0;
float* delayTimes = m_delayTimes.data();
double maxTime = maxDelayTime();
bool sampleAccurate = delayProcessor() && delayProcessor()->delayTime()->hasSampleAccurateValues();
if (sampleAccurate)
delayProcessor()->delayTime()->calculateSampleAccurateValues(delayTimes, framesToProcess);
else {
delayTime = delayProcessor() ? delayProcessor()->delayTime()->finalValue() : m_desiredDelayFrames / sampleRate;
// Make sure the delay time is in a valid range.
delayTime = min(maxTime, delayTime);
delayTime = max(0.0, delayTime);
if (m_firstTime) {
m_currentDelayTime = delayTime;
m_firstTime = false;
}
}
for (unsigned i = 0; i < framesToProcess; ++i) {
if (sampleAccurate) {
delayTime = delayTimes[i];
delayTime = std::min(maxTime, delayTime);
delayTime = std::max(0.0, delayTime);
m_currentDelayTime = delayTime;
} else {
// Approach desired delay time.
m_currentDelayTime += (delayTime - m_currentDelayTime) * m_smoothingRate;
}
double desiredDelayFrames = m_currentDelayTime * sampleRate;
double readPosition = m_writeIndex + bufferLength - desiredDelayFrames;
if (readPosition >= bufferLength)
readPosition -= bufferLength;
// Linearly interpolate in-between delay times.
int readIndex1 = static_cast<int>(readPosition);
int readIndex2 = (readIndex1 + 1) % bufferLength;
double interpolationFactor = readPosition - readIndex1;
double input = static_cast<float>(*source++);
buffer[m_writeIndex] = static_cast<float>(input);
m_writeIndex = (m_writeIndex + 1) % bufferLength;
double sample1 = buffer[readIndex1];
double sample2 = buffer[readIndex2];
double output = (1.0 - interpolationFactor) * sample1 + interpolationFactor * sample2;
*destination++ = static_cast<float>(output);
}
}
void DelayDSPKernel::reset()
{
m_firstTime = true;
m_buffer.zero();
}
double DelayDSPKernel::tailTime() const
{
return m_maxDelayTime;
}
double DelayDSPKernel::latencyTime() const
{
return 0;
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
|
