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
|
/*
* $Id$
*
* ***** BEGIN LGPL LICENSE BLOCK *****
*
* Copyright 2009 Jörg Hermann Müller
*
* This file is part of AudaSpace.
*
* AudaSpace is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* AudaSpace is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with AudaSpace. If not, see <http://www.gnu.org/licenses/>.
*
* ***** END LGPL LICENSE BLOCK *****
*/
#include "AUD_LowpassReader.h"
#include "AUD_Buffer.h"
#include <cstring>
#include <cmath>
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#define CC channels + channel
AUD_LowpassReader::AUD_LowpassReader(AUD_IReader* reader, float frequency,
float Q) :
AUD_EffectReader(reader)
{
AUD_Specs specs = reader->getSpecs();
int samplesize = AUD_SAMPLE_SIZE(specs);
m_buffer = new AUD_Buffer(); AUD_NEW("buffer")
m_outvalues = new AUD_Buffer(samplesize * AUD_LOWPASS_ORDER);
AUD_NEW("buffer")
memset(m_outvalues->getBuffer(), 0, samplesize * AUD_LOWPASS_ORDER);
m_invalues = new AUD_Buffer(samplesize * AUD_LOWPASS_ORDER);
AUD_NEW("buffer")
memset(m_invalues->getBuffer(), 0, samplesize * AUD_LOWPASS_ORDER);
m_position = 0;
// calculate coefficients
float w0 = 2 * M_PI * frequency / specs.rate;
float alpha = sin(w0) / (2 * Q);
float norm = 1 + alpha;
m_coeff[0][0] = 0;
m_coeff[0][1] = -2 * cos(w0) / norm;
m_coeff[0][2] = (1 - alpha) / norm;
m_coeff[1][2] = m_coeff[1][0] = (1 - cos(w0)) / (2 * norm);
m_coeff[1][1] = (1 - cos(w0)) / norm;
}
AUD_LowpassReader::~AUD_LowpassReader()
{
delete m_buffer; AUD_DELETE("buffer")
delete m_outvalues; AUD_DELETE("buffer")
delete m_invalues; AUD_DELETE("buffer");
}
void AUD_LowpassReader::read(int & length, sample_t* & buffer)
{
sample_t* buf;
sample_t* outvalues;
sample_t* invalues;
outvalues = m_outvalues->getBuffer();
invalues = m_invalues->getBuffer();
AUD_Specs specs = m_reader->getSpecs();
m_reader->read(length, buf);
if(m_buffer->getSize() < length * AUD_SAMPLE_SIZE(specs))
m_buffer->resize(length * AUD_SAMPLE_SIZE(specs));
buffer = m_buffer->getBuffer();
int channels = specs.channels;
for(int channel = 0; channel < channels; channel++)
{
for(int i = 0; i < length; i++)
{
invalues[m_position * CC] = buf[i * CC];
outvalues[m_position * CC] = 0;
for(int j = 0; j < AUD_LOWPASS_ORDER; j++)
{
outvalues[m_position * CC] += m_coeff[1][j] *
invalues[((m_position + j) % AUD_LOWPASS_ORDER) * CC] -
m_coeff[0][j] *
outvalues[((m_position + j) % AUD_LOWPASS_ORDER) * CC];
}
buffer[i * CC] = outvalues[m_position * CC];
m_position = (m_position + AUD_LOWPASS_ORDER-1) % AUD_LOWPASS_ORDER;
}
}
}
|
