jitterbuf.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2004-2005, Horizon Wimba, Inc.
   5  *
   6  * Contributors:
   7  * Steve Kann <stevek@stevek.com>
   8  *
   9  * Copyright on this file is disclaimed to Digium for inclusion in Asterisk
  10  *
  11  * See http://www.asterisk.org for more information about
  12  * the Asterisk project. Please do not directly contact
  13  * any of the maintainers of this project for assistance;
  14  * the project provides a web site, mailing lists and IRC
  15  * channels for your use.
  16  *
  17  * This program is free software, distributed under the terms of
  18  * the GNU General Public License Version 2. See the LICENSE file
  19  * at the top of the source tree.
  20  */
  21
  22 /*! \file
  23  *
  24  * \brief jitterbuf: an application-independent jitterbuffer
  25  * \author Steve Kann <stevek@stevek.com>
  26  *
  27  */
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32
  33 #include <sys/types.h>
  34 #include "asterisk.h"
  35
  36 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  37
  38 #include "jitterbuf.h"
  39 #include "asterisk/utils.h"
  40
  41 /*! define these here, just for ancient compiler systems */
  42 #define JB_LONGMAX 2147483647L
  43 #define JB_LONGMIN (-JB_LONGMAX - 1L)
  44
  45 #define jb_warn(...) (warnf ? warnf(__VA_ARGS__) : (void)0)
  46 #define jb_err(...) (errf ? errf(__VA_ARGS__) : (void)0)
  47 #define jb_dbg(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
  48
  49 #ifdef DEEP_DEBUG
  50 #define jb_dbg2(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
  51 #else
  52 #define jb_dbg2(...) ((void)0)
  53 #endif
  54
  55 static jb_output_function_t warnf, errf, dbgf;
  56
  57 void jb_setoutput(jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg)
  58 {
  59         errf = err;
  60         warnf = warn;
  61         dbgf = dbg;
  62 }
  63
  64 static void increment_losspct(jitterbuf *jb)
  65 {
  66         jb->info.losspct = (100000 + 499 * jb->info.losspct)/500;
  67 }
  68
  69 static void decrement_losspct(jitterbuf *jb)
  70 {
  71         jb->info.losspct = (499 * jb->info.losspct)/500;
  72 }
  73
  74 void jb_reset(jitterbuf *jb)
  75 {
  76         /* only save settings */
  77         jb_conf s = jb->info.conf;
  78         memset(jb, 0, sizeof(*jb));
  79         jb->info.conf = s;
  80
  81         /* initialize length */
  82         jb->info.current = jb->info.target = JB_TARGET_EXTRA;
  83         jb->info.silence_begin_ts = -1;
  84 }
  85
  86 jitterbuf * jb_new()
  87 {
  88         jitterbuf *jb;
  89
  90         if (!(jb = ast_malloc(sizeof(*jb))))
  91                 return NULL;
  92
  93         jb_reset(jb);
  94
  95         jb_dbg2("jb_new() = %x\n", jb);
  96         return jb;
  97 }
  98
  99 void jb_destroy(jitterbuf *jb)
 100 {
 101         jb_frame *frame;
 102         jb_dbg2("jb_destroy(%x)\n", jb);
 103
 104         /* free all the frames on the "free list" */
 105         frame = jb->free;
 106         while (frame != NULL) {
 107                 jb_frame *next = frame->next;
 108                 free(frame);
 109                 frame = next;
 110         }
 111
 112         /* free ourselves! */
 113         free(jb);
 114 }
 115
 116
 117
 118 #if 0
 119 static int longcmp(const void *a, const void *b)
 120 {
 121         return *(long *)a - *(long *)b;
 122 }
 123 #endif
 124
 125 /*!     \brief simple history manipulation
 126         \note maybe later we can make the history buckets variable size, or something? */
 127 /* drop parameter determines whether we will drop outliers to minimize
 128  * delay */
 129 static int history_put(jitterbuf *jb, long ts, long now, long ms)
 130 {
 131         long delay = now - (ts - jb->info.resync_offset);
 132         long threshold = 2 * jb->info.jitter + jb->info.conf.resync_threshold;
 133         long kicked;
 134
 135         /* don't add special/negative times to history */
 136         if (ts <= 0)
 137                 return 0;
 138
 139         /* check for drastic change in delay */
 140         if (jb->info.conf.resync_threshold != -1) {
 141                 if (abs(delay - jb->info.last_delay) > threshold) {
 142                         jb->info.cnt_delay_discont++;
 143                         if (jb->info.cnt_delay_discont > 3) {
 144                                 /* resync the jitterbuffer */
 145                                 jb->info.cnt_delay_discont = 0;
 146                                 jb->hist_ptr = 0;
 147                                 jb->hist_maxbuf_valid = 0;
 148
 149                                 jb_warn("Resyncing the jb. last_delay %ld, this delay %ld, threshold %ld, new offset %ld\n", jb->info.last_delay, delay, threshold, ts - now);
 150                                 jb->info.resync_offset = ts - now;
 151                                 jb->info.last_delay = delay = 0; /* after resync, frame is right on time */
 152                         } else {
 153                                 return -1;
 154                         }
 155                 } else {
 156                         jb->info.last_delay = delay;
 157                         jb->info.cnt_delay_discont = 0;
 158                 }
 159         }
 160
 161         kicked = jb->history[jb->hist_ptr % JB_HISTORY_SZ];
 162
 163         jb->history[(jb->hist_ptr++) % JB_HISTORY_SZ] = delay;
 164
 165         /* optimization; the max/min buffers don't need to be recalculated, if this packet's
 166          * entry doesn't change them.  This happens if this packet is not involved, _and_ any packet
 167          * that got kicked out of the history is also not involved
 168          * We do a number of comparisons, but it's probably still worthwhile, because it will usually
 169          * succeed, and should be a lot faster than going through all 500 packets in history */
 170         if (!jb->hist_maxbuf_valid)
 171                 return 0;
 172
 173         /* don't do this until we've filled history
 174          * (reduces some edge cases below) */
 175         if (jb->hist_ptr < JB_HISTORY_SZ)
 176                 goto invalidate;
 177
 178         /* if the new delay would go into min */
 179         if (delay < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])
 180                 goto invalidate;
 181
 182         /* or max.. */
 183         if (delay > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])
 184                 goto invalidate;
 185
 186         /* or the kicked delay would be in min */
 187         if (kicked <= jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])
 188                 goto invalidate;
 189
 190         if (kicked >= jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])
 191                 goto invalidate;
 192
 193         /* if we got here, we don't need to invalidate, 'cause this delay didn't
 194          * affect things */
 195         return 0;
 196         /* end optimization */
 197
 198
 199 invalidate:
 200         jb->hist_maxbuf_valid = 0;
 201         return 0;
 202 }
 203
 204 static void history_calc_maxbuf(jitterbuf *jb)
 205 {
 206         int i,j;
 207
 208         if (jb->hist_ptr == 0)
 209                 return;
 210
 211
 212         /* initialize maxbuf/minbuf to the latest value */
 213         for (i=0;i<JB_HISTORY_MAXBUF_SZ;i++) {
 214 /*
 215  * jb->hist_maxbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
 216  * jb->hist_minbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
 217  */
 218                 jb->hist_maxbuf[i] = JB_LONGMIN;
 219                 jb->hist_minbuf[i] = JB_LONGMAX;
 220         }
 221
 222         /* use insertion sort to populate maxbuf */
 223         /* we want it to be the top "n" values, in order */
 224
 225         /* start at the beginning, or JB_HISTORY_SZ frames ago */
 226         i = (jb->hist_ptr > JB_HISTORY_SZ) ? (jb->hist_ptr - JB_HISTORY_SZ) : 0;
 227
 228         for (;i<jb->hist_ptr;i++) {
 229                 long toins = jb->history[i % JB_HISTORY_SZ];
 230
 231                 /* if the maxbuf should get this */
 232                 if (toins > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])  {
 233
 234                         /* insertion-sort it into the maxbuf */
 235                         for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
 236                                 /* found where it fits */
 237                                 if (toins > jb->hist_maxbuf[j]) {
 238                                         /* move over */
 239                                         memmove(jb->hist_maxbuf + j + 1, jb->hist_maxbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_maxbuf[0]));
 240                                         /* insert */
 241                                         jb->hist_maxbuf[j] = toins;
 242
 243                                         break;
 244                                 }
 245                         }
 246                 }
 247
 248                 /* if the minbuf should get this */
 249                 if (toins < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])  {
 250
 251                         /* insertion-sort it into the maxbuf */
 252                         for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
 253                                 /* found where it fits */
 254                                 if (toins < jb->hist_minbuf[j]) {
 255                                         /* move over */
 256                                         memmove(jb->hist_minbuf + j + 1, jb->hist_minbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_minbuf[0]));
 257                                         /* insert */
 258                                         jb->hist_minbuf[j] = toins;
 259
 260                                         break;
 261                                 }
 262                         }
 263                 }
 264
 265                 if (0) {
 266                         int k;
 267                         fprintf(stderr, "toins = %ld\n", toins);
 268                         fprintf(stderr, "maxbuf =");
 269                         for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++)
 270                                 fprintf(stderr, "%ld ", jb->hist_maxbuf[k]);
 271                         fprintf(stderr, "\nminbuf =");
 272                         for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++)
 273                                 fprintf(stderr, "%ld ", jb->hist_minbuf[k]);
 274                         fprintf(stderr, "\n");
 275                 }
 276         }
 277
 278         jb->hist_maxbuf_valid = 1;
 279 }
 280
 281 static void history_get(jitterbuf *jb)
 282 {
 283         long max, min, jitter;
 284         int index;
 285         int count;
 286
 287         if (!jb->hist_maxbuf_valid)
 288                 history_calc_maxbuf(jb);
 289
 290         /* count is how many items in history we're examining */
 291         count = (jb->hist_ptr < JB_HISTORY_SZ) ? jb->hist_ptr : JB_HISTORY_SZ;
 292
 293         /* index is the "n"ths highest/lowest that we'll look for */
 294         index = count * JB_HISTORY_DROPPCT / 100;
 295
 296         /* sanity checks for index */
 297         if (index > (JB_HISTORY_MAXBUF_SZ - 1))
 298                 index = JB_HISTORY_MAXBUF_SZ - 1;
 299
 300
 301         if (index < 0) {
 302                 jb->info.min = 0;
 303                 jb->info.jitter = 0;
 304                 return;
 305         }
 306
 307         max = jb->hist_maxbuf[index];
 308         min = jb->hist_minbuf[index];
 309
 310         jitter = max - min;
 311
 312         /* these debug stmts compare the difference between looking at the absolute jitter, and the
 313          * values we get by throwing away the outliers */
 314         /*
 315         fprintf(stderr, "[%d] min=%d, max=%d, jitter=%d\n", index, min, max, jitter);
 316         fprintf(stderr, "[%d] min=%d, max=%d, jitter=%d\n", 0, jb->hist_minbuf[0], jb->hist_maxbuf[0], jb->hist_maxbuf[0]-jb->hist_minbuf[0]);
 317         */
 318
 319         jb->info.min = min;
 320         jb->info.jitter = jitter;
 321 }
 322
 323 /* returns 1 if frame was inserted into head of queue, 0 otherwise */
 324 static int queue_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts)
 325 {
 326         jb_frame *frame;
 327         jb_frame *p;
 328         int head = 0;
 329         long resync_ts = ts - jb->info.resync_offset;
 330
 331         if ((frame = jb->free)) {
 332                 jb->free = frame->next;
 333         } else if (!(frame = ast_malloc(sizeof(*frame)))) {
 334                 jb_err("cannot allocate frame\n");
 335                 return 0;
 336         }
 337
 338         jb->info.frames_cur++;
 339
 340         frame->data = data;
 341         frame->ts = resync_ts;
 342         frame->ms = ms;
 343         frame->type = type;
 344
 345         /*
 346          * frames are a circular list, jb-frames points to to the lowest ts,
 347          * jb->frames->prev points to the highest ts
 348          */
 349
 350         if (!jb->frames) {  /* queue is empty */
 351                 jb->frames = frame;
 352                 frame->next = frame;
 353                 frame->prev = frame;
 354                 head = 1;
 355         } else if (resync_ts < jb->frames->ts) {
 356                 frame->next = jb->frames;
 357                 frame->prev = jb->frames->prev;
 358
 359                 frame->next->prev = frame;
 360                 frame->prev->next = frame;
 361
 362                 /* frame is out of order */
 363                 jb->info.frames_ooo++;
 364
 365                 jb->frames = frame;
 366                 head = 1;
 367         } else {
 368                 p = jb->frames;
 369
 370                 /* frame is out of order */
 371                 if (resync_ts < p->prev->ts) jb->info.frames_ooo++;
 372
 373                 while (resync_ts < p->prev->ts && p->prev != jb->frames)
 374                         p = p->prev;
 375
 376                 frame->next = p;
 377                 frame->prev = p->prev;
 378
 379                 frame->next->prev = frame;
 380                 frame->prev->next = frame;
 381         }
 382         return head;
 383 }
 384
 385 static long queue_next(jitterbuf *jb)
 386 {
 387         if (jb->frames)
 388                 return jb->frames->ts;
 389         else
 390                 return -1;
 391 }
 392
 393 static long queue_last(jitterbuf *jb)
 394 {
 395         if (jb->frames)
 396                 return jb->frames->prev->ts;
 397         else
 398                 return -1;
 399 }
 400
 401 static jb_frame *_queue_get(jitterbuf *jb, long ts, int all)
 402 {
 403         jb_frame *frame;
 404         frame = jb->frames;
 405
 406         if (!frame)
 407                 return NULL;
 408
 409         /*jb_warn("queue_get: ASK %ld FIRST %ld\n", ts, frame->ts); */
 410
 411         if (all || ts >= frame->ts) {
 412                 /* remove this frame */
 413                 frame->prev->next = frame->next;
 414                 frame->next->prev = frame->prev;
 415
 416                 if (frame->next == frame)
 417                         jb->frames = NULL;
 418                 else
 419                         jb->frames = frame->next;
 420
 421
 422                 /* insert onto "free" single-linked list */
 423                 frame->next = jb->free;
 424                 jb->free = frame;
 425
 426                 jb->info.frames_cur--;
 427
 428                 /* we return the frame pointer, even though it's on free list,
 429                  * but caller must copy data */
 430                 return frame;
 431         }
 432
 433         return NULL;
 434 }
 435
 436 static jb_frame *queue_get(jitterbuf *jb, long ts)
 437 {
 438         return _queue_get(jb,ts,0);
 439 }
 440
 441 static jb_frame *queue_getall(jitterbuf *jb)
 442 {
 443         return _queue_get(jb,0,1);
 444 }
 445
 446 #if 0
 447 /* some diagnostics */
 448 static void jb_dbginfo(jitterbuf *jb)
 449 {
 450         if (dbgf == NULL)
 451                 return;
 452
 453         jb_dbg("\njb info: fin=%ld fout=%ld flate=%ld flost=%ld fdrop=%ld fcur=%ld\n",
 454                 jb->info.frames_in, jb->info.frames_out, jb->info.frames_late, jb->info.frames_lost, jb->info.frames_dropped, jb->info.frames_cur);
 455
 456         jb_dbg("jitter=%ld current=%ld target=%ld min=%ld sil=%d len=%d len/fcur=%ld\n",
 457                 jb->info.jitter, jb->info.current, jb->info.target, jb->info.min, jb->info.silence_begin_ts, jb->info.current - jb->info.min,
 458                 jb->info.frames_cur ? (jb->info.current - jb->info.min)/jb->info.frames_cur : -8);
 459         if (jb->info.frames_in > 0)
 460                 jb_dbg("jb info: Loss PCT = %ld%%, Late PCT = %ld%%\n",
 461                         jb->info.frames_lost * 100/(jb->info.frames_in + jb->info.frames_lost),
 462                         jb->info.frames_late * 100/jb->info.frames_in);
 463         jb_dbg("jb info: queue %d -> %d.  last_ts %d (queue len: %d) last_ms %d\n",
 464                 queue_next(jb),
 465                 queue_last(jb),
 466                 jb->info.next_voice_ts,
 467                 queue_last(jb) - queue_next(jb),
 468                 jb->info.last_voice_ms);
 469 }
 470 #endif
 471
 472 #ifdef DEEP_DEBUG
 473 static void jb_chkqueue(jitterbuf *jb)
 474 {
 475         int i=0;
 476         jb_frame *p = jb->frames;
 477
 478         if (!p) {
 479                 return;
 480         }
 481
 482         do {
 483                 if (p->next == NULL)  {
 484                         jb_err("Queue is BROKEN at item [%d]", i);
 485                 }
 486                 i++;
 487                 p=p->next;
 488         } while (p->next != jb->frames);
 489 }
 490
 491 static void jb_dbgqueue(jitterbuf *jb)
 492 {
 493         int i=0;
 494         jb_frame *p = jb->frames;
 495
 496         jb_dbg("queue: ");
 497
 498         if (!p) {
 499                 jb_dbg("EMPTY\n");
 500                 return;
 501         }
 502
 503         do {
 504                 jb_dbg("[%d]=%ld ", i++, p->ts);
 505                 p=p->next;
 506         } while (p->next != jb->frames);
 507
 508         jb_dbg("\n");
 509 }
 510 #endif
 511
 512 enum jb_return_code jb_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts, long now)
 513 {
 514         jb_dbg2("jb_put(%x,%x,%ld,%ld,%ld)\n", jb, data, ms, ts, now);
 515
 516         jb->info.frames_in++;
 517
 518         if (type == JB_TYPE_VOICE) {
 519                 /* presently, I'm only adding VOICE frames to history and drift calculations; mostly because with the
 520                  * IAX integrations, I'm sending retransmitted control frames with their awkward timestamps through */
 521                 if (history_put(jb,ts,now,ms))
 522                         return JB_DROP;
 523         }
 524
 525         /* if put into head of queue, caller needs to reschedule */
 526         if (queue_put(jb,data,type,ms,ts)) {
 527                 return JB_SCHED;
 528         }
 529         return JB_OK;
 530 }
 531
 532
 533 static enum jb_return_code _jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl)
 534 {
 535         jb_frame *frame;
 536         long diff;
 537         static int dbg_cnt = 0;
 538
 539         /*if ((now - jb_next(jb)) > 2 * jb->info.last_voice_ms) jb_warn("SCHED: %ld", (now - jb_next(jb))); */
 540         /* get jitter info */
 541         history_get(jb);
 542
 543         if (dbg_cnt && dbg_cnt % 50 == 0) {
 544                 jb_dbg("\n");
 545         }
 546         dbg_cnt++;
 547
 548         /* target */
 549         jb->info.target = jb->info.jitter + jb->info.min + JB_TARGET_EXTRA;
 550
 551         /* if a hard clamp was requested, use it */
 552         if ((jb->info.conf.max_jitterbuf) && ((jb->info.target - jb->info.min) > jb->info.conf.max_jitterbuf)) {
 553                 jb_dbg("clamping target from %d to %d\n", (jb->info.target - jb->info.min), jb->info.conf.max_jitterbuf);
 554                 jb->info.target = jb->info.min + jb->info.conf.max_jitterbuf;
 555         }
 556
 557         diff = jb->info.target - jb->info.current;
 558
 559         /* jb_warn("diff = %d lms=%d last = %d now = %d\n", diff,  */
 560         /*      jb->info.last_voice_ms, jb->info.last_adjustment, now); */
 561
 562         /* let's work on non-silent case first */
 563         if (!jb->info.silence_begin_ts) {
 564                 /* we want to grow */
 565                 if ((diff > 0) &&
 566                         /* we haven't grown in the delay length */
 567                         (((jb->info.last_adjustment + JB_ADJUST_DELAY) < now) ||
 568                         /* we need to grow more than the "length" we have left */
 569                         (diff > queue_last(jb)  - queue_next(jb)) ) ) {
 570                         /* grow by interp frame length */
 571                         jb->info.current += interpl;
 572                         jb->info.next_voice_ts += interpl;
 573                         jb->info.last_voice_ms = interpl;
 574                         jb->info.last_adjustment = now;
 575                         jb->info.cnt_contig_interp++;
 576                         if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
 577                                 jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
 578                         }
 579                         jb_dbg("G");
 580                         return JB_INTERP;
 581                 }
 582
 583                 frame = queue_get(jb, jb->info.next_voice_ts - jb->info.current);
 584
 585                 /* not a voice frame; just return it. */
 586                 if (frame && frame->type != JB_TYPE_VOICE) {
 587                         if (frame->type == JB_TYPE_SILENCE) {
 588                                 jb->info.silence_begin_ts = frame->ts;
 589                                 jb->info.cnt_contig_interp = 0;
 590                         }
 591
 592                         *frameout = *frame;
 593                         jb->info.frames_out++;
 594                         jb_dbg("o");
 595                         return JB_OK;
 596                 }
 597
 598
 599                 /* voice frame is later than expected */
 600                 if (frame && frame->ts + jb->info.current < jb->info.next_voice_ts) {
 601                         if (frame->ts + jb->info.current > jb->info.next_voice_ts - jb->info.last_voice_ms) {
 602                                 /* either we interpolated past this frame in the last jb_get */
 603                                 /* or the frame is still in order, but came a little too quick */
 604                                 *frameout = *frame;
 605                                 /* reset expectation for next frame */
 606                                 jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
 607                                 jb->info.frames_out++;
 608                                 decrement_losspct(jb);
 609                                 jb->info.cnt_contig_interp = 0;
 610                                 jb_dbg("v");
 611                                 return JB_OK;
 612                         } else {
 613                                 /* voice frame is late */
 614                                 *frameout = *frame;
 615                                 jb->info.frames_out++;
 616                                 decrement_losspct(jb);
 617                                 jb->info.frames_late++;
 618                                 jb->info.frames_lost--;
 619                                 jb_dbg("l");
 620                                 /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
 621                                 jb_warninfo(jb); */
 622                                 return JB_DROP;
 623                         }
 624                 }
 625
 626                 /* keep track of frame sizes, to allow for variable sized-frames */
 627                 if (frame && frame->ms > 0) {
 628                         jb->info.last_voice_ms = frame->ms;
 629                 }
 630
 631                 /* we want to shrink; shrink at 1 frame / 500ms */
 632                 /* unless we don't have a frame, then shrink 1 frame */
 633                 /* every 80ms (though perhaps we can shrink even faster */
 634                 /* in this case) */
 635                 if (diff < -JB_TARGET_EXTRA &&
 636                         ((!frame && jb->info.last_adjustment + 80 < now) ||
 637                         (jb->info.last_adjustment + 500 < now))) {
 638
 639                         jb->info.last_adjustment = now;
 640                         jb->info.cnt_contig_interp = 0;
 641
 642                         if (frame) {
 643                                 *frameout = *frame;
 644                                 /* shrink by frame size we're throwing out */
 645                                 jb->info.current -= frame->ms;
 646                                 jb->info.frames_out++;
 647                                 decrement_losspct(jb);
 648                                 jb->info.frames_dropped++;
 649                                 jb_dbg("s");
 650                                 return JB_DROP;
 651                         } else {
 652                                 /* shrink by last_voice_ms */
 653                                 jb->info.current -= jb->info.last_voice_ms;
 654                                 jb->info.frames_lost++;
 655                                 increment_losspct(jb);
 656                                 jb_dbg("S");
 657                                 return JB_NOFRAME;
 658                         }
 659                 }
 660
 661                 /* lost frame */
 662                 if (!frame) {
 663                         /* this is a bit of a hack for now, but if we're close to
 664                          * target, and we find a missing frame, it makes sense to
 665                          * grow, because the frame might just be a bit late;
 666                          * otherwise, we presently get into a pattern where we return
 667                          * INTERP for the lost frame, then it shows up next, and we
 668                          * throw it away because it's late */
 669                         /* I've recently only been able to replicate this using
 670                          * iaxclient talking to app_echo on asterisk.  In this case,
 671                          * my outgoing packets go through asterisk's (old)
 672                          * jitterbuffer, and then might get an unusual increasing delay
 673                          * there if it decides to grow?? */
 674                         /* Update: that might have been a different bug, that has been fixed..
 675                          * But, this still seemed like a good idea, except that it ended up making a single actual
 676                          * lost frame get interpolated two or more times, when there was "room" to grow, so it might
 677                          * be a bit of a bad idea overall */
 678                         /*if (diff > -1 * jb->info.last_voice_ms) {
 679                                 jb->info.current += jb->info.last_voice_ms;
 680                                 jb->info.last_adjustment = now;
 681                                 jb_warn("g");
 682                                 return JB_INTERP;
 683                         } */
 684                         jb->info.frames_lost++;
 685                         increment_losspct(jb);
 686                         jb->info.next_voice_ts += interpl;
 687                         jb->info.last_voice_ms = interpl;
 688                         jb->info.cnt_contig_interp++;
 689                         if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
 690                                 jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
 691                         }
 692                         jb_dbg("L");
 693                         return JB_INTERP;
 694                 }
 695
 696                 /* normal case; return the frame, increment stuff */
 697                 *frameout = *frame;
 698                 jb->info.next_voice_ts += frame->ms;
 699                 jb->info.frames_out++;
 700                 jb->info.cnt_contig_interp = 0;
 701                 decrement_losspct(jb);
 702                 jb_dbg("v");
 703                 return JB_OK;
 704         } else {
 705                 /* TODO: after we get the non-silent case down, we'll make the
 706                  * silent case -- basically, we'll just grow and shrink faster
 707                  * here, plus handle next_voice_ts a bit differently */
 708
 709                 /* to disable silent special case altogether, just uncomment this: */
 710                 /* jb->info.silence_begin_ts = 0; */
 711
 712                 /* shrink interpl len every 10ms during silence */
 713                 if (diff < -JB_TARGET_EXTRA &&
 714                         jb->info.last_adjustment + 10 <= now) {
 715                         jb->info.current -= interpl;
 716                         jb->info.last_adjustment = now;
 717                 }
 718
 719                 frame = queue_get(jb, now - jb->info.current);
 720                 if (!frame) {
 721                         return JB_NOFRAME;
 722                 } else if (frame->type != JB_TYPE_VOICE) {
 723                         /* normal case; in silent mode, got a non-voice frame */
 724                         *frameout = *frame;
 725                         jb->info.frames_out++;
 726                         return JB_OK;
 727                 }
 728                 if (frame->ts < jb->info.silence_begin_ts) {
 729                         /* voice frame is late */
 730                         *frameout = *frame;
 731                         jb->info.frames_out++;
 732                         decrement_losspct(jb);
 733                         jb->info.frames_late++;
 734                         jb->info.frames_lost--;
 735                         jb_dbg("l");
 736                         /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
 737                         jb_warninfo(jb); */
 738                         return JB_DROP;
 739                 } else {
 740                         /* voice frame */
 741                         /* try setting current to target right away here */
 742                         jb->info.current = jb->info.target;
 743                         jb->info.silence_begin_ts = 0;
 744                         jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
 745                         jb->info.last_voice_ms = frame->ms;
 746                         jb->info.frames_out++;
 747                         decrement_losspct(jb);
 748                         *frameout = *frame;
 749                         jb_dbg("V");
 750                         return JB_OK;
 751                 }
 752         }
 753 }
 754
 755 long jb_next(jitterbuf *jb)
 756 {
 757         if (jb->info.silence_begin_ts) {
 758                 long next = queue_next(jb);
 759                 if (next > 0) {
 760                         history_get(jb);
 761                         /* shrink during silence */
 762                         if (jb->info.target - jb->info.current < -JB_TARGET_EXTRA)
 763                                 return jb->info.last_adjustment + 10;
 764                         return next + jb->info.target;
 765                 }
 766                 else
 767                         return JB_LONGMAX;
 768         } else {
 769                 return jb->info.next_voice_ts;
 770         }
 771 }
 772
 773 enum jb_return_code jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl)
 774 {
 775         enum jb_return_code ret = _jb_get(jb, frameout, now, interpl);
 776 #if 0
 777         static int lastts=0;
 778         int thists = ((ret == JB_OK) || (ret == JB_DROP)) ? frameout->ts : 0;
 779         jb_warn("jb_get(%x,%x,%ld) = %d (%d)\n", jb, frameout, now, ret, thists);
 780         if (thists && thists < lastts) jb_warn("XXXX timestamp roll-back!!!\n");
 781         lastts = thists;
 782 #endif
 783         if(ret == JB_INTERP)
 784                 frameout->ms = jb->info.last_voice_ms;
 785
 786         return ret;
 787 }
 788
 789 enum jb_return_code jb_getall(jitterbuf *jb, jb_frame *frameout)
 790 {
 791         jb_frame *frame;
 792         frame = queue_getall(jb);
 793
 794         if (!frame) {
 795                 return JB_NOFRAME;
 796         }
 797
 798         *frameout = *frame;
 799         return JB_OK;
 800 }
 801
 802
 803 enum jb_return_code jb_getinfo(jitterbuf *jb, jb_info *stats)
 804 {
 805
 806         history_get(jb);
 807
 808         *stats = jb->info;
 809
 810         return JB_OK;
 811 }
 812
 813 enum jb_return_code jb_setconf(jitterbuf *jb, jb_conf *conf)
 814 {
 815         /* take selected settings from the struct */
 816
 817         jb->info.conf.max_jitterbuf = conf->max_jitterbuf;
 818         jb->info.conf.resync_threshold = conf->resync_threshold;
 819         jb->info.conf.max_contig_interp = conf->max_contig_interp;
 820
 821         return JB_OK;
 822 }
 823
 824