blob: 1877c341b1d5df5927f0d0ef7c190610d9dfcaec (
plain)
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
|
/*
* Purpose: Application to local playback buffer resampling routine for vmix
*
* This file is almost the same than playmix.inc but uses simple
* linear interpolation algorithm for sample rate conversion.
*/
/*
*
* This file is part of Open Sound System.
*
* Copyright (C) 4Front Technologies 1996-2008.
*
* This this source file is released under GPL v2 license (no other versions).
* See the COPYING file included in the main directory of this source
* distribution for the license terms and conditions.
*
*/
/*
* Mixing function for virtual devices
*/
vmix_mixer_t *mixer = portc->mixer;
vmix_engine_t *eng = &mixer->play_engine;
dmap_t *dmap = audio_engines[portc->audio_dev]->dmap_out;
int frame_size;
int inptr, inmax;
int used_channels;
int i, ch, nch;
double vol, step;
double tmp;
/*
* Initial setup
*/
step = (double) portc->rate / (double) mixer->play_engine.rate;
#if 1
/*
* TODO:
* For some reason "trivial" conversion rations such as 4:1, 2:1, 1:2 and 1:4
* don't work properly. As a workaround we add a tiny error to break the
* evil ratio. Need to find out why the algorithm doesn't work with such ratios.
*/
if (step==4.0)step=4.0001;
if (step==2.0)step=2.0001;
if (step==0.5)step=0.5001;
if (step==0.25)step=0.25001;
#endif
frame_size = sizeof (*inp);
inmax = dmap->bytes_in_use / frame_size / portc->channels;
inptr = (int)(portc->play_dma_pointer_src / frame_size / portc->channels);
used_channels = portc->channels;
if (used_channels > eng->channels)
used_channels = eng->channels;
/* ignored_channels = portc->channels - used_channels; */
/*
* Handle mono playback by playing the mono stream twice (for left and right ch)
*/
nch=used_channels;
if (nch<2)nch=2;
/*
* Do the mixing
*/
for (ch = 0; ch < nch; ch++)
{
double ip = inptr + (ch%used_channels);
double vu = portc->vu[ch % 2];
float *chbuf = eng->chbufs[ch+portc->play_choffs];
inp = (BUFFER_TYPE) dmap->dmabuf;
inp += ch;
i = portc->volume[ch%2];
vol = vmix_db_table[i / 5];
vu = vu / 255.0;
for (i = 0; i < nsamples; i++)
{
double frag, tmp_next;
int ip_next;
#if 0 && defined(SINE_DEBUG)
if (ch > 1)
tmp = 0.0;
else
tmp = sine_table[sine_phase[ch]];
sine_phase[ch] = (sine_phase[ch] + 1) % SINE_SIZE;
#else
/*
* Convert the sample to right endianess.
*/
tmp = VMIX_BYTESWAP (inp[((int) ip) * portc->channels]);
/* perform linear interpolation */
ip_next = (((int) ip) + 1) % inmax;
tmp_next = VMIX_BYTESWAP (inp[ip_next * portc->channels]);
frag = ip - (int) ip; /* Pointer fraction */
tmp += (tmp_next - tmp) * frag;
tmp /= 2.0;
tmp = tmp * range;
#endif
tmp = tmp * vol;
*chbuf++ += tmp;
ip = ip + step;
if (ip > inmax)
ip -= inmax;
/* VU meter */
if (tmp < 0.0)
tmp = -tmp;
if (tmp > vu)
vu = tmp;
}
if (ch < 2)
{ /* Save left/right VU meters */
vu = vu * 255.0;
portc->vu[ch] = (int)vu;
}
}
/*
* Finally save the state variables
*/
tmp = (nsamples * frame_size * portc->channels);
tmp *= step;
portc->play_dma_pointer_src = portc->play_dma_pointer_src + tmp;
if (portc->play_dma_pointer_src > dmap->bytes_in_use)
portc->play_dma_pointer_src -= dmap->bytes_in_use;
portc->play_dma_pointer = (int)portc->play_dma_pointer_src;
frame_size *= portc->channels;
portc->play_dma_pointer = (portc->play_dma_pointer / frame_size) * frame_size;
|
