#include <stdint.h>
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Defines | |
| #define | _PLC_H_ |
| #define | CORRELATION_SPAN 160 |
| #define | PLC_HISTORY_LEN (CORRELATION_SPAN + PLC_PITCH_MIN) |
| #define | PLC_PITCH_MAX 40 |
| #define | PLC_PITCH_MIN 120 |
| #define | PLC_PITCH_OVERLAP_MAX (PLC_PITCH_MIN >> 2) |
| #define | SAMPLE_RATE 8000 |
Functions | |
| int | plc_fillin (plc_state_t *s, int16_t amp[], int len) |
| Fill-in a block of missing audio samples. | |
| plc_state_t * | plc_init (plc_state_t *s) |
| Process a block of received V.29 modem audio samples. | |
| int | plc_rx (plc_state_t *s, int16_t amp[], int len) |
| Process a block of received audio samples. | |
All rights reserved.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
This version may be optionally licenced under the GNU LGPL licence.
A license has been granted to Digium (via disclaimer) for the use of this code.
Definition in file plc.h.
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The length over which the AMDF function looks for similarity (20 ms) Definition at line 109 of file plc.h. Referenced by plc_fillin(). |
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History buffer length. The buffer much also be at leat 1.25 times PLC_PITCH_MIN, but that is much smaller than the buffer needs to be for the pitch assessment. Definition at line 113 of file plc.h. Referenced by normalise_history(), plc_fillin(), and save_history(). |
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Maximum allowed pitch (200 Hz) Definition at line 105 of file plc.h. Referenced by plc_fillin(). |
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Minimum allowed pitch (66 Hz) Definition at line 103 of file plc.h. Referenced by plc_fillin(). |
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Maximum pitch OLA window |
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Fill-in a block of missing audio samples. Fill-in a block of missing audio samples.
Definition at line 174 of file plc.c. References amdf_pitch(), ATTENUATION_INCREMENT, CORRELATION_SPAN, fsaturate(), plc_state_t::history, plc_state_t::missing_samples, normalise_history(), plc_state_t::pitch, plc_state_t::pitch_offset, plc_state_t::pitchbuf, PLC_HISTORY_LEN, PLC_PITCH_MAX, PLC_PITCH_MIN, and save_history(). Referenced by adpcmtolin_framein(), alawtolin_framein(), g726tolin_framein(), gsmtolin_framein(), lpc10tolin_framein(), and ulawtolin_framein(). 00175 {
00176 int i;
00177 int pitch_overlap;
00178 float old_step;
00179 float new_step;
00180 float old_weight;
00181 float new_weight;
00182 float gain;
00183 int16_t *orig_amp;
00184 int orig_len;
00185
00186 orig_amp = amp;
00187 orig_len = len;
00188 if (s->missing_samples == 0) {
00189 /* As the gap in real speech starts we need to assess the last known pitch,
00190 and prepare the synthetic data we will use for fill-in */
00191 normalise_history(s);
00192 s->pitch = amdf_pitch(PLC_PITCH_MIN, PLC_PITCH_MAX, s->history + PLC_HISTORY_LEN - CORRELATION_SPAN - PLC_PITCH_MIN, CORRELATION_SPAN);
00193 /* We overlap a 1/4 wavelength */
00194 pitch_overlap = s->pitch >> 2;
00195 /* Cook up a single cycle of pitch, using a single of the real signal with 1/4
00196 cycle OLA'ed to make the ends join up nicely */
00197 /* The first 3/4 of the cycle is a simple copy */
00198 for (i = 0; i < s->pitch - pitch_overlap; i++)
00199 s->pitchbuf[i] = s->history[PLC_HISTORY_LEN - s->pitch + i];
00200 /* The last 1/4 of the cycle is overlapped with the end of the previous cycle */
00201 new_step = 1.0/pitch_overlap;
00202 new_weight = new_step;
00203 for ( ; i < s->pitch; i++) {
00204 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;
00205 new_weight += new_step;
00206 }
00207 /* We should now be ready to fill in the gap with repeated, decaying cycles
00208 of what is in pitchbuf */
00209
00210 /* We need to OLA the first 1/4 wavelength of the synthetic data, to smooth
00211 it into the previous real data. To avoid the need to introduce a delay
00212 in the stream, reverse the last 1/4 wavelength, and OLA with that. */
00213 gain = 1.0;
00214 new_step = 1.0/pitch_overlap;
00215 old_step = new_step;
00216 new_weight = new_step;
00217 old_weight = 1.0 - new_step;
00218 for (i = 0; i < pitch_overlap; i++) {
00219 amp[i] = fsaturate(old_weight*s->history[PLC_HISTORY_LEN - 1 - i] + new_weight*s->pitchbuf[i]);
00220 new_weight += new_step;
00221 old_weight -= old_step;
00222 if (old_weight < 0.0)
00223 old_weight = 0.0;
00224 }
00225 s->pitch_offset = i;
00226 } else {
00227 gain = 1.0 - s->missing_samples*ATTENUATION_INCREMENT;
00228 i = 0;
00229 }
00230 for ( ; gain > 0.0 && i < len; i++) {
00231 amp[i] = s->pitchbuf[s->pitch_offset]*gain;
00232 gain -= ATTENUATION_INCREMENT;
00233 if (++s->pitch_offset >= s->pitch)
00234 s->pitch_offset = 0;
00235 }
00236 for ( ; i < len; i++)
00237 amp[i] = 0;
00238 s->missing_samples += orig_len;
00239 save_history(s, amp, len);
00240 return len;
00241 }
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Process a block of received V.29 modem audio samples. Process a block of received V.29 modem audio samples.
Definition at line 245 of file plc.c. Referenced by adpcmtolin_new(), alawtolin_new(), g726tolin_new(), gsm_new(), lpc10_dec_new(), and ulawtolin_new(). 00246 {
00247 memset(s, 0, sizeof(*s));
00248 return s;
00249 }
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Process a block of received audio samples. Process a block of received audio samples.
Definition at line 131 of file plc.c. References ATTENUATION_INCREMENT, fsaturate(), and save_history(). Referenced by adpcmtolin_framein(), alawtolin_framein(), g726tolin_framein(), gsmtolin_framein(), lpc10tolin_framein(), and ulawtolin_framein(). 00132 {
00133 int i;
00134 int pitch_overlap;
00135 float old_step;
00136 float new_step;
00137 float old_weight;
00138 float new_weight;
00139 float gain;
00140
00141 if (s->missing_samples) {
00142 /* Although we have a real signal, we need to smooth it to fit well
00143 with the synthetic signal we used for the previous block */
00144
00145 /* The start of the real data is overlapped with the next 1/4 cycle
00146 of the synthetic data. */
00147 pitch_overlap = s->pitch >> 2;
00148 if (pitch_overlap > len)
00149 pitch_overlap = len;
00150 gain = 1.0 - s->missing_samples*ATTENUATION_INCREMENT;
00151 if (gain < 0.0)
00152 gain = 0.0;
00153 new_step = 1.0/pitch_overlap;
00154 old_step = new_step*gain;
00155 new_weight = new_step;
00156 old_weight = (1.0 - new_step)*gain;
00157 for (i = 0; i < pitch_overlap; i++) {
00158 amp[i] = fsaturate(old_weight*s->pitchbuf[s->pitch_offset] + new_weight*amp[i]);
00159 if (++s->pitch_offset >= s->pitch)
00160 s->pitch_offset = 0;
00161 new_weight += new_step;
00162 old_weight -= old_step;
00163 if (old_weight < 0.0)
00164 old_weight = 0.0;
00165 }
00166 s->missing_samples = 0;
00167 }
00168 save_history(s, amp, len);
00169 return len;
00170 }
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1.4.2