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
178
179
180
181
182
183
184
|
/**
* OpenAL cross platform audio library
* Copyright (C) 2009 by Chris Robinson.
* 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; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <math.h>
#include <stdlib.h>
#include "alMain.h"
#include "alFilter.h"
#include "alAuxEffectSlot.h"
#include "alError.h"
#include "alu.h"
typedef struct ALechoState {
// Must be first in all effects!
ALeffectState state;
ALfloat *SampleBuffer;
ALuint BufferLength;
// The echo is two tap. The delay is the number of samples from before the
// current offset
struct {
ALuint delay;
} Tap[2];
ALuint Offset;
/* The panning gains for the two taps */
ALfloat Gain[2][MAXCHANNELS];
ALfloat FeedGain;
FILTER iirFilter;
ALfloat history[2];
} ALechoState;
static ALvoid EchoDestroy(ALeffectState *effect)
{
ALechoState *state = (ALechoState*)effect;
if(state)
{
free(state->SampleBuffer);
state->SampleBuffer = NULL;
free(state);
}
}
static ALboolean EchoDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
{
ALechoState *state = (ALechoState*)effect;
ALuint maxlen, i;
// Use the next power of 2 for the buffer length, so the tap offsets can be
// wrapped using a mask instead of a modulo
maxlen = fastf2u(AL_ECHO_MAX_DELAY * Device->Frequency) + 1;
maxlen += fastf2u(AL_ECHO_MAX_LRDELAY * Device->Frequency) + 1;
maxlen = NextPowerOf2(maxlen);
if(maxlen != state->BufferLength)
{
void *temp;
temp = realloc(state->SampleBuffer, maxlen * sizeof(ALfloat));
if(!temp)
return AL_FALSE;
state->SampleBuffer = temp;
state->BufferLength = maxlen;
}
for(i = 0;i < state->BufferLength;i++)
state->SampleBuffer[i] = 0.0f;
return AL_TRUE;
}
static ALvoid EchoUpdate(ALeffectState *effect, ALCdevice *Device, const ALeffectslot *Slot)
{
ALechoState *state = (ALechoState*)effect;
ALuint frequency = Device->Frequency;
ALfloat lrpan, cw, g, gain;
ALfloat dirGain;
ALuint i;
state->Tap[0].delay = fastf2u(Slot->effect.Echo.Delay * frequency) + 1;
state->Tap[1].delay = fastf2u(Slot->effect.Echo.LRDelay * frequency);
state->Tap[1].delay += state->Tap[0].delay;
lrpan = Slot->effect.Echo.Spread;
state->FeedGain = Slot->effect.Echo.Feedback;
cw = aluCos(F_PI*2.0f * LOWPASSFREQREF / frequency);
g = 1.0f - Slot->effect.Echo.Damping;
state->iirFilter.coeff = lpCoeffCalc(g, cw);
gain = Slot->Gain;
for(i = 0;i < MAXCHANNELS;i++)
{
state->Gain[0][i] = 0.0f;
state->Gain[1][i] = 0.0f;
}
dirGain = aluFabs(lrpan);
/* First tap panning */
ComputeAngleGains(Device, aluAtan2(-lrpan, 0.0f), (1.0f-dirGain)*F_PI, gain, state->Gain[0]);
/* Second tap panning */
ComputeAngleGains(Device, aluAtan2(+lrpan, 0.0f), (1.0f-dirGain)*F_PI, gain, state->Gain[1]);
}
static ALvoid EchoProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[MAXCHANNELS])
{
ALechoState *state = (ALechoState*)effect;
const ALuint mask = state->BufferLength-1;
const ALuint tap1 = state->Tap[0].delay;
const ALuint tap2 = state->Tap[1].delay;
ALuint offset = state->Offset;
ALfloat smp;
ALuint i, k;
for(i = 0;i < SamplesToDo;i++,offset++)
{
/* First tap */
smp = state->SampleBuffer[(offset-tap1) & mask];
for(k = 0;k < MAXCHANNELS;k++)
SamplesOut[i][k] += smp * state->Gain[0][k];
/* Second tap */
smp = state->SampleBuffer[(offset-tap2) & mask];
for(k = 0;k < MAXCHANNELS;k++)
SamplesOut[i][k] += smp * state->Gain[1][k];
// Apply damping and feedback gain to the second tap, and mix in the
// new sample
smp = lpFilter2P(&state->iirFilter, 0, smp+SamplesIn[i]);
state->SampleBuffer[offset&mask] = smp * state->FeedGain;
}
state->Offset = offset;
}
ALeffectState *EchoCreate(void)
{
ALechoState *state;
state = malloc(sizeof(*state));
if(!state)
return NULL;
state->state.Destroy = EchoDestroy;
state->state.DeviceUpdate = EchoDeviceUpdate;
state->state.Update = EchoUpdate;
state->state.Process = EchoProcess;
state->BufferLength = 0;
state->SampleBuffer = NULL;
state->Tap[0].delay = 0;
state->Tap[1].delay = 0;
state->Offset = 0;
state->iirFilter.coeff = 0.0f;
state->iirFilter.history[0] = 0.0f;
state->iirFilter.history[1] = 0.0f;
return &state->state;
}
|
