loader: Correct overly strict startup checks.
[asterisk/asterisk.git] / main / plc.c
1 /*
2  * Asterisk -- An open source telephony toolkit.
3  *
4  * Written by Steve Underwood <steveu@coppice.org>
5  *
6  * Copyright (C) 2004 Steve Underwood
7  *
8  * All rights reserved.
9  *
10  * See http://www.asterisk.org for more information about
11  * the Asterisk project. Please do not directly contact
12  * any of the maintainers of this project for assistance;
13  * the project provides a web site, mailing lists and IRC
14  * channels for your use.
15  *
16  * This program is free software, distributed under the terms of
17  * the GNU General Public License Version 2. See the LICENSE file
18  * at the top of the source tree.
19  *
20  * This version may be optionally licenced under the GNU LGPL licence.
21  *
22  * A license has been granted to Digium (via disclaimer) for the use of
23  * this code.
24  */
25
26 /*! \file
27  *
28  * \brief SpanDSP - a series of DSP components for telephony
29  *
30  * \author Steve Underwood <steveu@coppice.org>
31  */
32
33 /*** MODULEINFO
34         <support_level>core</support_level>
35  ***/
36
37 #include "asterisk.h"
38
39 #include <math.h>
40
41 #include "asterisk/plc.h"
42
43 #if !defined(FALSE)
44 #define FALSE 0
45 #endif
46 #if !defined(TRUE)
47 #define TRUE (!FALSE)
48 #endif
49
50 #if !defined(INT16_MAX)
51 #define INT16_MAX       (32767)
52 #define INT16_MIN       (-32767-1)
53 #endif
54
55 /* We do a straight line fade to zero volume in 50ms when we are filling in for missing data. */
56 #define ATTENUATION_INCREMENT       0.0025                            /* Attenuation per sample */
57
58 #define ms_to_samples(t)            (((t)*DEFAULT_SAMPLE_RATE)/1000)
59
60 static inline int16_t fsaturate(double damp)
61 {
62         if (damp > 32767.0)
63                 return  INT16_MAX;
64         if (damp < -32768.0)
65                 return  INT16_MIN;
66         return (int16_t) rint(damp);
67 }
68
69 static void save_history(plc_state_t *s, int16_t *buf, int len)
70 {
71         if (len >= PLC_HISTORY_LEN) {
72                 /* Just keep the last part of the new data, starting at the beginning of the buffer */
73                  memcpy(s->history, buf + len - PLC_HISTORY_LEN, sizeof(int16_t) * PLC_HISTORY_LEN);
74                 s->buf_ptr = 0;
75                 return;
76         }
77         if (s->buf_ptr + len > PLC_HISTORY_LEN) {
78                 /* Wraps around - must break into two sections */
79                 memcpy(s->history + s->buf_ptr, buf, sizeof(int16_t) * (PLC_HISTORY_LEN - s->buf_ptr));
80                 len -= (PLC_HISTORY_LEN - s->buf_ptr);
81                 memcpy(s->history, buf + (PLC_HISTORY_LEN - s->buf_ptr), sizeof(int16_t)*len);
82                 s->buf_ptr = len;
83                 return;
84         }
85         /* Can use just one section */
86         memcpy(s->history + s->buf_ptr, buf, sizeof(int16_t)*len);
87         s->buf_ptr += len;
88 }
89
90 /*- End of function --------------------------------------------------------*/
91
92 static void normalise_history(plc_state_t *s)
93 {
94         int16_t tmp[PLC_HISTORY_LEN];
95
96         if (s->buf_ptr == 0)
97                 return;
98         memcpy(tmp, s->history, sizeof(int16_t)*s->buf_ptr);
99         memmove(s->history, s->history + s->buf_ptr, sizeof(int16_t) * (PLC_HISTORY_LEN - s->buf_ptr));
100         memcpy(s->history + PLC_HISTORY_LEN - s->buf_ptr, tmp, sizeof(int16_t) * s->buf_ptr);
101         s->buf_ptr = 0;
102 }
103
104 /*- End of function --------------------------------------------------------*/
105
106 static int __inline__ amdf_pitch(int min_pitch, int max_pitch, int16_t amp[], int len)
107 {
108         int i;
109         int j;
110         int acc;
111         int min_acc;
112         int pitch;
113
114         pitch = min_pitch;
115         min_acc = INT_MAX;
116         for (i = max_pitch; i <= min_pitch; i++) {
117                 acc = 0;
118                 for (j = 0; j < len; j++)
119                         acc += abs(amp[i + j] - amp[j]);
120                 if (acc < min_acc) {
121                         min_acc = acc;
122                         pitch = i;
123                 }
124         }
125         return pitch;
126 }
127
128 /*- End of function --------------------------------------------------------*/
129
130 int plc_rx(plc_state_t *s, int16_t amp[], int len)
131 {
132         int i;
133         int pitch_overlap;
134         float old_step;
135         float new_step;
136         float old_weight;
137         float new_weight;
138         float gain;
139
140         if (s->missing_samples) {
141                 /* Although we have a real signal, we need to smooth it to fit well
142                 with the synthetic signal we used for the previous block */
143
144                 /* The start of the real data is overlapped with the next 1/4 cycle
145                    of the synthetic data. */
146                 pitch_overlap = s->pitch >> 2;
147                 if (pitch_overlap > len)
148                         pitch_overlap = len;
149                 gain = 1.0 - s->missing_samples*ATTENUATION_INCREMENT;
150                 if (gain < 0.0)
151                         gain = 0.0;
152                 new_step = 1.0/pitch_overlap;
153                 old_step = new_step*gain;
154                 new_weight = new_step;
155                 old_weight = (1.0 - new_step)*gain;
156                 for (i = 0; i < pitch_overlap; i++) {
157                         amp[i] = fsaturate(old_weight * s->pitchbuf[s->pitch_offset] + new_weight * amp[i]);
158                         if (++s->pitch_offset >= s->pitch)
159                                 s->pitch_offset = 0;
160                         new_weight += new_step;
161                         old_weight -= old_step;
162                         if (old_weight < 0.0)
163                                 old_weight = 0.0;
164                 }
165                 s->missing_samples = 0;
166         }
167         save_history(s, amp, len);
168         return len;
169 }
170
171 /*- End of function --------------------------------------------------------*/
172
173 int plc_fillin(plc_state_t *s, int16_t amp[], int len)
174 {
175         int i;
176         int pitch_overlap;
177         float old_step;
178         float new_step;
179         float old_weight;
180         float new_weight;
181         float gain;
182         int orig_len;
183
184         orig_len = len;
185         if (s->missing_samples == 0) {
186                 /* As the gap in real speech starts we need to assess the last known pitch,
187                 and prepare the synthetic data we will use for fill-in */
188                 normalise_history(s);
189                 s->pitch = amdf_pitch(PLC_PITCH_MIN, PLC_PITCH_MAX, s->history + PLC_HISTORY_LEN - CORRELATION_SPAN - PLC_PITCH_MIN, CORRELATION_SPAN);
190                 /* We overlap a 1/4 wavelength */
191                 pitch_overlap = s->pitch >> 2;
192                 /* Cook up a single cycle of pitch, using a single of the real signal with 1/4
193                 cycle OLA'ed to make the ends join up nicely */
194                 /* The first 3/4 of the cycle is a simple copy */
195                 for (i = 0;  i < s->pitch - pitch_overlap;  i++)
196                         s->pitchbuf[i] = s->history[PLC_HISTORY_LEN - s->pitch + i];
197                 /* The last 1/4 of the cycle is overlapped with the end of the previous cycle */
198                 new_step = 1.0/pitch_overlap;
199                 new_weight = new_step;
200                 for ( ; i < s->pitch; i++) {
201                         s->pitchbuf[i] = s->history[PLC_HISTORY_LEN - s->pitch + i] * (1.0 - new_weight) + s->history[PLC_HISTORY_LEN - 2 * s->pitch + i]*new_weight;
202                         new_weight += new_step;
203                 }
204                 /* We should now be ready to fill in the gap with repeated, decaying cycles
205                 of what is in pitchbuf */
206
207                 /* We need to OLA the first 1/4 wavelength of the synthetic data, to smooth
208                 it into the previous real data. To avoid the need to introduce a delay
209                 in the stream, reverse the last 1/4 wavelength, and OLA with that. */
210                 gain = 1.0;
211                 new_step = 1.0 / pitch_overlap;
212                 old_step = new_step;
213                 new_weight = new_step;
214                 old_weight = 1.0 - new_step;
215                 for (i = 0; i < pitch_overlap; i++) {
216                         amp[i] = fsaturate(old_weight * s->history[PLC_HISTORY_LEN - 1 - i] + new_weight * s->pitchbuf[i]);
217                         new_weight += new_step;
218                         old_weight -= old_step;
219                         if (old_weight < 0.0)
220                                 old_weight = 0.0;
221                 }
222                 s->pitch_offset = i;
223         } else {
224                 gain = 1.0 - s->missing_samples*ATTENUATION_INCREMENT;
225                 i = 0;
226         }
227         for ( ; gain > 0.0 && i < len; i++) {
228                 amp[i] = s->pitchbuf[s->pitch_offset] * gain;
229                 gain -= ATTENUATION_INCREMENT;
230                 if (++s->pitch_offset >= s->pitch)
231                         s->pitch_offset = 0;
232         }
233         for ( ; i < len; i++)
234                 amp[i] = 0;
235         s->missing_samples += orig_len;
236         save_history(s, amp, len);
237         return len;
238 }
239
240 /*- End of function --------------------------------------------------------*/
241
242 plc_state_t *plc_init(plc_state_t *s)
243 {
244         memset(s, 0, sizeof(*s));
245         return s;
246 }
247 /*- End of function --------------------------------------------------------*/
248 /*- End of file ------------------------------------------------------------*/