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
|
/*
Copyright (C) 2000 Jeff Tranter
tranter@pobox.com
Stefan Westerfeld
stefan@space.twc.de
Jens Hahn
Jens.Hahn@t-online.de
2001 Matthias Kretz
kretz@kde.org
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "artsmodulessynth.h"
#include "stdsynthmodule.h"
#include <math.h>
using namespace Arts;
// This delays the input signal for an amount of time. The time
// specification must be between 0 and 1 for a delay between 0 seconds
// and 1 second.
//
// This kind of delay may not be used in feedback structures. This is
// because it's a variable delay. You can modify it's length while it
// is running, and even set it down to zero. But since in a feedback
// structure the own output is needed to calculate the next samples, a
// delay whose value could drop to zero during synthesis could lead to
// a stall situation.
//
// Use CDELAYs in that setup, perhaps combine a small constant delay
// (of 0.001 seconds) with a flexible delay.
//
// You can also combine a CDELAY and a DELAY to achieve a variable
// length delay with a minimum value in a feedback loop. Just make
// sure that you have a CDELAY involved.
class Synth_DELAY_impl : virtual public Synth_DELAY_skel,
virtual public StdSynthModule
{
protected:
unsigned long _buffersize;
unsigned long _bitmask;
float * _buffer;
float _maxdelay;
unsigned int _writepos;
public:
Synth_DELAY_impl() : _buffersize( 0 ), _bitmask( 0 ), _buffer( 0 ), _maxdelay( 0 ), _writepos( 0 )
{
maxdelay( 1 ); // take a one second buffer if nothing else is specified
}
~Synth_DELAY_impl()
{
delete[] _buffer;
}
void streamInit()
{
// initialize buffer to all zeroes
for ( unsigned long i = 0; i < _buffersize; i++ )
_buffer[i] = 0.0;
}
void calculateBlock(unsigned long samples)
{
for( unsigned long i = 0; i <samples; i++ )
{
double int_pos;
double error = modf( time[i] * samplingRateFloat, &int_pos );
unsigned long readpos1 = ( _writepos - (unsigned long)(int_pos) ) & _bitmask;
unsigned long readpos2 = ( readpos1 - 1 ) & _bitmask; // Shouldn't this be +1? (mkretz)
// No, it's right this way:
// ( 1 - error ) needs to be multiplied with the second
// sample; error with the first
_buffer[_writepos] = invalue[i];
outvalue[i] = _buffer[readpos1] * ( 1 - error ) + _buffer[readpos2] * error;
_writepos++;
_writepos &= _bitmask;
}
}
float maxdelay() { return _maxdelay; }
void maxdelay(float newmaxdelay)
{
if( newmaxdelay <= 0 )
return;
_maxdelay = newmaxdelay;
double n = ceil( log( double(_maxdelay * samplingRateFloat) ) / log( 2. ) );
unsigned long newbuffersize = (unsigned long)( pow( 2, n ) );
unsigned long newbitmask = newbuffersize - 1;
if( newbuffersize != _buffersize )
{
float *newbuffer = new float[newbuffersize];
if( newbuffersize > _buffersize ) {
for( unsigned long i = 0; i < _buffersize; i++ ) {
newbuffer[i] = _buffer[_writepos];
_writepos++;
_writepos &= newbitmask;
}
for( unsigned long i = _buffersize; i < newbuffersize; i++ )
newbuffer[i] = 0;
} else {
_writepos -= newbuffersize;
_writepos &= newbitmask;
for( unsigned long i = 0; i < newbuffersize; i++ ) {
newbuffer[i] = _buffer[_writepos];
_writepos++;
_writepos &= newbitmask;
}
}
_buffer = newbuffer;
_buffersize = newbuffersize;
_bitmask = newbitmask;
}
maxdelay_changed( _maxdelay );
}
};
REGISTER_IMPLEMENTATION(Synth_DELAY_impl);
|
