forked from PaulStoffregen/Audio
-
Notifications
You must be signed in to change notification settings - Fork 0
/
filter_variable.h
83 lines (79 loc) · 3.06 KB
/
filter_variable.h
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
/* Audio Library for Teensy 3.X
* Copyright (c) 2014, Paul Stoffregen, [email protected]
*
* Development of this audio library was funded by PJRC.COM, LLC by sales of
* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
* open source software by purchasing Teensy or other PJRC products.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef filter_variable_h_
#define filter_variable_h_
#include "AudioStream.h"
class AudioFilterStateVariable: public AudioStream
{
public:
AudioFilterStateVariable() : AudioStream(2, inputQueueArray) {
frequency(1000);
octaveControl(1.0); // default values
resonance(0.707);
state_inputprev = 0;
state_lowpass = 0;
state_bandpass = 0;
}
void frequency(float freq) {
if (freq < 20.0) freq = 20.0;
else if (freq > AUDIO_SAMPLE_RATE_EXACT/2.5) freq = AUDIO_SAMPLE_RATE_EXACT/2.5;
setting_fcenter = (freq * (3.141592654/(AUDIO_SAMPLE_RATE_EXACT*2.0)))
* 2147483647.0;
// TODO: should we use an approximation when freq is not a const,
// so the sinf() function isn't linked?
setting_fmult = sinf(freq * (3.141592654/(AUDIO_SAMPLE_RATE_EXACT*2.0)))
* 2147483647.0;
}
void resonance(float q) {
if (q < 0.7) q = 0.7;
else if (q > 5.0) q = 5.0;
// TODO: allow lower Q when frequency is lower
setting_damp = (1.0 / q) * 1073741824.0;
}
void octaveControl(float n) {
// filter's corner frequency is Fcenter * 2^(control * N)
// where "control" ranges from -1.0 to +1.0
// and "N" allows the frequency to change from 0 to 7 octaves
if (n < 0.0) n = 0.0;
else if (n > 6.9999) n = 6.9999;
setting_octavemult = n * 4096.0;
}
virtual void update(void);
private:
void update_fixed(const int16_t *in,
int16_t *lp, int16_t *bp, int16_t *hp);
void update_variable(const int16_t *in, const int16_t *ctl,
int16_t *lp, int16_t *bp, int16_t *hp);
int32_t setting_fcenter;
int32_t setting_fmult;
int32_t setting_octavemult;
int32_t setting_damp;
int32_t state_inputprev;
int32_t state_lowpass;
int32_t state_bandpass;
audio_block_t *inputQueueArray[2];
};
#endif