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comparison spandsp-0.0.3/spandsp-0.0.3/src/plc.c @ 5:f762bf195c4b

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import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
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4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * plc.c
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2004 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: plc.c,v 1.16 2006/11/19 14:07:24 steveu Exp $
26 */
27
28 /*! \file */
29
30 #ifdef HAVE_CONFIG_H
31 #include <config.h>
32 #endif
33
34 #include <stdio.h>
35 #include <inttypes.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #if defined(HAVE_TGMATH_H)
39 #include <tgmath.h>
40 #endif
41 #if defined(HAVE_MATH_H)
42 #include <math.h>
43 #endif
44 #include <limits.h>
45
46 #include "spandsp/telephony.h"
47 #include "spandsp/dc_restore.h"
48 #include "spandsp/plc.h"
49
50 /* We do a straight line fade to zero volume in 50ms when we are filling in for missing data. */
51 #define ATTENUATION_INCREMENT 0.0025f /* Attenuation per sample */
52
53 #define ms_to_samples(t) (((t)*SAMPLE_RATE)/1000)
54
55 static void save_history(plc_state_t *s, int16_t *buf, int len)
56 {
57 if (len >= PLC_HISTORY_LEN)
58 {
59 /* Just keep the last part of the new data, starting at the beginning of the buffer */
60 memcpy(s->history, buf + len - PLC_HISTORY_LEN, sizeof(int16_t)*PLC_HISTORY_LEN);
61 s->buf_ptr = 0;
62 return;
63 }
64 if (s->buf_ptr + len > PLC_HISTORY_LEN)
65 {
66 /* Wraps around - must break into two sections */
67 memcpy(s->history + s->buf_ptr, buf, sizeof(int16_t)*(PLC_HISTORY_LEN - s->buf_ptr));
68 len -= (PLC_HISTORY_LEN - s->buf_ptr);
69 memcpy(s->history, buf + (PLC_HISTORY_LEN - s->buf_ptr), sizeof(int16_t)*len);
70 s->buf_ptr = len;
71 return;
72 }
73 /* Can use just one section */
74 memcpy(s->history + s->buf_ptr, buf, sizeof(int16_t)*len);
75 s->buf_ptr += len;
76 }
77 /*- End of function --------------------------------------------------------*/
78
79 static __inline__ void normalise_history(plc_state_t *s)
80 {
81 int16_t tmp[PLC_HISTORY_LEN];
82
83 if (s->buf_ptr == 0)
84 return;
85 memcpy(tmp, s->history, sizeof(int16_t)*s->buf_ptr);
86 memcpy(s->history, s->history + s->buf_ptr, sizeof(int16_t)*(PLC_HISTORY_LEN - s->buf_ptr));
87 memcpy(s->history + PLC_HISTORY_LEN - s->buf_ptr, tmp, sizeof(int16_t)*s->buf_ptr);
88 s->buf_ptr = 0;
89 }
90 /*- End of function --------------------------------------------------------*/
91
92 static __inline__ int amdf_pitch(int min_pitch, int max_pitch, int16_t amp[], int len)
93 {
94 int i;
95 int j;
96 int acc;
97 int min_acc;
98 int pitch;
99
100 pitch = min_pitch;
101 min_acc = INT_MAX;
102 for (i = max_pitch; i <= min_pitch; i++)
103 {
104 acc = 0;
105 for (j = 0; j < len; j++)
106 acc += abs(amp[i + j] - amp[j]);
107 if (acc < min_acc)
108 {
109 min_acc = acc;
110 pitch = i;
111 }
112 }
113 return pitch;
114 }
115 /*- End of function --------------------------------------------------------*/
116
117 int plc_rx(plc_state_t *s, int16_t amp[], int len)
118 {
119 int i;
120 int pitch_overlap;
121 float old_step;
122 float new_step;
123 float old_weight;
124 float new_weight;
125 float gain;
126
127 if (s->missing_samples)
128 {
129 /* Although we have a real signal, we need to smooth it to fit well
130 with the synthetic signal we used for the previous block */
131
132 /* The start of the real data is overlapped with the next 1/4 cycle
133 of the synthetic data. */
134 pitch_overlap = s->pitch >> 2;
135 if (pitch_overlap > len)
136 pitch_overlap = len;
137 gain = 1.0f - s->missing_samples*ATTENUATION_INCREMENT;
138 if (gain < 0.0f)
139 gain = 0.0f;
140 new_step = 1.0f/pitch_overlap;
141 old_step = new_step*gain;
142 new_weight = new_step;
143 old_weight = (1.0f - new_step)*gain;
144 for (i = 0; i < pitch_overlap; i++)
145 {
146 amp[i] = fsaturate(old_weight*s->pitchbuf[s->pitch_offset] + new_weight*amp[i]);
147 if (++s->pitch_offset >= s->pitch)
148 s->pitch_offset = 0;
149 new_weight += new_step;
150 old_weight -= old_step;
151 if (old_weight < 0.0f)
152 old_weight = 0.0f;
153 }
154 s->missing_samples = 0;
155 }
156 save_history(s, amp, len);
157 return len;
158 }
159 /*- End of function --------------------------------------------------------*/
160
161 int plc_fillin(plc_state_t *s, int16_t amp[], int len)
162 {
163 int i;
164 int pitch_overlap;
165 float old_step;
166 float new_step;
167 float old_weight;
168 float new_weight;
169 float gain;
170 int16_t *orig_amp;
171 int orig_len;
172
173 orig_amp = amp;
174 orig_len = len;
175 if (s->missing_samples == 0)
176 {
177 /* As the gap in real speech starts we need to assess the last known pitch,
178 and prepare the synthetic data we will use for fill-in */
179 normalise_history(s);
180 s->pitch = amdf_pitch(PLC_PITCH_MIN, PLC_PITCH_MAX, s->history + PLC_HISTORY_LEN - CORRELATION_SPAN - PLC_PITCH_MIN, CORRELATION_SPAN);
181 /* We overlap a 1/4 wavelength */
182 pitch_overlap = s->pitch >> 2;
183 /* Cook up a single cycle of pitch, using a single of the real signal with 1/4
184 cycle OLA'ed to make the ends join up nicely */
185 /* The first 3/4 of the cycle is a simple copy */
186 for (i = 0; i < s->pitch - pitch_overlap; i++)
187 s->pitchbuf[i] = s->history[PLC_HISTORY_LEN - s->pitch + i];
188 /* The last 1/4 of the cycle is overlapped with the end of the previous cycle */
189 new_step = 1.0f/pitch_overlap;
190 new_weight = new_step;
191 for ( ; i < s->pitch; i++)
192 {
193 s->pitchbuf[i] = s->history[PLC_HISTORY_LEN - s->pitch + i]*(1.0f - new_weight) + s->history[PLC_HISTORY_LEN - 2*s->pitch + i]*new_weight;
194 new_weight += new_step;
195 }
196 /* We should now be ready to fill in the gap with repeated, decaying cycles
197 of what is in pitchbuf */
198
199 gain = 1.0f;
200 /* We need to OLA the first 1/4 wavelength of the synthetic data, to smooth
201 it into the previous real data. To avoid the need to introduce a delay
202 in the stream, reverse the last 1/4 wavelength, and OLA with that. */
203 new_step = 1.0f/pitch_overlap;
204 old_step = new_step;
205 new_weight = new_step;
206 old_weight = 1.0f - new_step;
207 for (i = 0; i < pitch_overlap; i++)
208 {
209 amp[i] = fsaturate(old_weight*s->history[PLC_HISTORY_LEN - 1 - i] + new_weight*s->pitchbuf[i]);
210 new_weight += new_step;
211 old_weight -= old_step;
212 if (old_weight < 0.0f)
213 old_weight = 0.0f;
214 }
215 s->pitch_offset = i;
216 }
217 else
218 {
219 gain = 1.0f - s->missing_samples*ATTENUATION_INCREMENT;
220 i = 0;
221 }
222 for ( ; gain > 0.0f && i < len; i++)
223 {
224 amp[i] = (int16_t) (s->pitchbuf[s->pitch_offset]*gain);
225 gain -= ATTENUATION_INCREMENT;
226 if (++s->pitch_offset >= s->pitch)
227 s->pitch_offset = 0;
228 }
229 for ( ; i < len; i++)
230 amp[i] = 0;
231 s->missing_samples += orig_len;
232 save_history(s, amp, len);
233 return len;
234 }
235 /*- End of function --------------------------------------------------------*/
236
237 plc_state_t *plc_init(plc_state_t *s)
238 {
239 if (s == NULL)
240 {
241 if ((s = (plc_state_t *) malloc(sizeof(*s))) == NULL)
242 return NULL;
243 }
244 memset(s, 0, sizeof(*s));
245 return s;
246 }
247 /*- End of function --------------------------------------------------------*/
248
249 int plc_release(plc_state_t *s)
250 {
251 free(s);
252 return 0;
253 }
254 /*- End of function --------------------------------------------------------*/
255 /*- End of file ------------------------------------------------------------*/

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