Thu Jul 9 13:40:36 2009

Asterisk developer's documentation


jitterbuf.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2004-2005, Horizon Wimba, Inc.
00005  *
00006  * Contributors:
00007  * Steve Kann <stevek@stevek.com>
00008  *
00009  * A license has been granted to Digium (via disclaimer) for the use of
00010  * this code.
00011  *
00012  * See http://www.asterisk.org for more information about
00013  * the Asterisk project. Please do not directly contact
00014  * any of the maintainers of this project for assistance;
00015  * the project provides a web site, mailing lists and IRC
00016  * channels for your use.
00017  *
00018  * This program is free software, distributed under the terms of
00019  * the GNU General Public License Version 2. See the LICENSE file
00020  * at the top of the source tree.
00021  */
00022 
00023 /*! \file
00024  *
00025  * \brief jitterbuf: an application-independent jitterbuffer
00026  * \author Steve Kann <stevek@stevek.com>
00027  *
00028  */
00029 
00030 #include "asterisk.h"
00031 
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 174596 $")
00033 
00034 #include "jitterbuf.h"
00035 #include "asterisk/utils.h"
00036 
00037 /*! define these here, just for ancient compiler systems */
00038 #define JB_LONGMAX 2147483647L
00039 #define JB_LONGMIN (-JB_LONGMAX - 1L)
00040 
00041 #define jb_warn(...) (warnf ? warnf(__VA_ARGS__) : (void)0)
00042 #define jb_err(...) (errf ? errf(__VA_ARGS__) : (void)0)
00043 #define jb_dbg(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
00044 
00045 #ifdef DEEP_DEBUG
00046 #define jb_dbg2(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
00047 #else
00048 #define jb_dbg2(...) ((void)0)
00049 #endif
00050 
00051 static jb_output_function_t warnf, errf, dbgf;
00052 
00053 void jb_setoutput(jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg) 
00054 {
00055    errf = err;
00056    warnf = warn;
00057    dbgf = dbg;
00058 }
00059 
00060 static void increment_losspct(jitterbuf *jb) 
00061 {
00062    jb->info.losspct = (100000 + 499 * jb->info.losspct)/500;    
00063 }
00064 
00065 static void decrement_losspct(jitterbuf *jb) 
00066 {
00067    jb->info.losspct = (499 * jb->info.losspct)/500;    
00068 }
00069 
00070 void jb_reset(jitterbuf *jb) 
00071 {
00072    /* only save settings */
00073    jb_conf s = jb->info.conf;
00074    memset(jb, 0, sizeof(*jb));
00075    jb->info.conf = s;
00076 
00077    /* initialize length, using the default value */
00078    jb->info.current = jb->info.target = jb->info.conf.target_extra = JB_TARGET_EXTRA;
00079    jb->info.silence_begin_ts = -1; 
00080 }
00081 
00082 jitterbuf * jb_new() 
00083 {
00084    jitterbuf *jb;
00085 
00086    if (!(jb = ast_malloc(sizeof(*jb)))) 
00087       return NULL;
00088 
00089    jb_reset(jb);
00090 
00091    jb_dbg2("jb_new() = %x\n", jb);
00092    return jb;
00093 }
00094 
00095 void jb_destroy(jitterbuf *jb) 
00096 {
00097    jb_frame *frame; 
00098    jb_dbg2("jb_destroy(%x)\n", jb);
00099 
00100    /* free all the frames on the "free list" */
00101    frame = jb->free;
00102    while (frame != NULL) {
00103       jb_frame *next = frame->next;
00104       ast_free(frame);
00105       frame = next;
00106    }
00107 
00108    /* free ourselves! */ 
00109    ast_free(jb);
00110 }
00111 
00112 
00113 
00114 #if 0
00115 static int longcmp(const void *a, const void *b) 
00116 {
00117    return *(long *)a - *(long *)b;
00118 }
00119 #endif
00120 
00121 /*!   \brief simple history manipulation 
00122    \note maybe later we can make the history buckets variable size, or something? */
00123 /* drop parameter determines whether we will drop outliers to minimize
00124  * delay */
00125 static int history_put(jitterbuf *jb, long ts, long now, long ms) 
00126 {
00127    long delay = now - (ts - jb->info.resync_offset);
00128    long threshold = 2 * jb->info.jitter + jb->info.conf.resync_threshold;
00129    long kicked;
00130 
00131    /* don't add special/negative times to history */
00132    if (ts <= 0) 
00133       return 0;
00134 
00135    /* check for drastic change in delay */
00136    if (jb->info.conf.resync_threshold != -1) {
00137       if (abs(delay - jb->info.last_delay) > threshold) {
00138          jb->info.cnt_delay_discont++;
00139          if (jb->info.cnt_delay_discont > 3) {
00140             /* resync the jitterbuffer */
00141             jb->info.cnt_delay_discont = 0;
00142             jb->hist_ptr = 0;
00143             jb->hist_maxbuf_valid = 0;
00144 
00145             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);
00146             jb->info.resync_offset = ts - now;
00147             jb->info.last_delay = delay = 0; /* after resync, frame is right on time */
00148          } else {
00149             return -1;
00150          }
00151       } else {
00152          jb->info.last_delay = delay;
00153          jb->info.cnt_delay_discont = 0;
00154       }
00155    }
00156 
00157    kicked = jb->history[jb->hist_ptr % JB_HISTORY_SZ];
00158 
00159    jb->history[(jb->hist_ptr++) % JB_HISTORY_SZ] = delay;
00160 
00161    /* optimization; the max/min buffers don't need to be recalculated, if this packet's
00162     * entry doesn't change them.  This happens if this packet is not involved, _and_ any packet
00163     * that got kicked out of the history is also not involved 
00164     * We do a number of comparisons, but it's probably still worthwhile, because it will usually
00165     * succeed, and should be a lot faster than going through all 500 packets in history */
00166    if (!jb->hist_maxbuf_valid)
00167       return 0;
00168 
00169    /* don't do this until we've filled history 
00170     * (reduces some edge cases below) */
00171    if (jb->hist_ptr < JB_HISTORY_SZ)
00172       goto invalidate;
00173 
00174    /* if the new delay would go into min */
00175    if (delay < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])
00176       goto invalidate;
00177 
00178    /* or max.. */
00179    if (delay > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])
00180       goto invalidate;
00181 
00182    /* or the kicked delay would be in min */
00183    if (kicked <= jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1]) 
00184       goto invalidate;
00185 
00186    if (kicked >= jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1]) 
00187       goto invalidate;
00188 
00189    /* if we got here, we don't need to invalidate, 'cause this delay didn't 
00190     * affect things */
00191    return 0;
00192    /* end optimization */
00193 
00194 
00195 invalidate:
00196    jb->hist_maxbuf_valid = 0;
00197    return 0;
00198 }
00199 
00200 static void history_calc_maxbuf(jitterbuf *jb) 
00201 {
00202    int i,j;
00203 
00204    if (jb->hist_ptr == 0) 
00205       return;
00206 
00207 
00208    /* initialize maxbuf/minbuf to the latest value */
00209    for (i=0;i<JB_HISTORY_MAXBUF_SZ;i++) {
00210 /*
00211  * jb->hist_maxbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
00212  * jb->hist_minbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
00213  */
00214       jb->hist_maxbuf[i] = JB_LONGMIN;
00215       jb->hist_minbuf[i] = JB_LONGMAX;
00216    }
00217 
00218    /* use insertion sort to populate maxbuf */
00219    /* we want it to be the top "n" values, in order */
00220 
00221    /* start at the beginning, or JB_HISTORY_SZ frames ago */
00222    i = (jb->hist_ptr > JB_HISTORY_SZ) ? (jb->hist_ptr - JB_HISTORY_SZ) : 0; 
00223 
00224    for (;i<jb->hist_ptr;i++) {
00225       long toins = jb->history[i % JB_HISTORY_SZ];
00226 
00227       /* if the maxbuf should get this */
00228       if (toins > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])  {
00229 
00230          /* insertion-sort it into the maxbuf */
00231          for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
00232             /* found where it fits */
00233             if (toins > jb->hist_maxbuf[j]) {
00234                /* move over */
00235                memmove(jb->hist_maxbuf + j + 1, jb->hist_maxbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_maxbuf[0]));
00236                /* insert */
00237                jb->hist_maxbuf[j] = toins;
00238 
00239                break;
00240             }
00241          }
00242       }
00243 
00244       /* if the minbuf should get this */
00245       if (toins < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])  {
00246 
00247          /* insertion-sort it into the maxbuf */
00248          for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
00249             /* found where it fits */
00250             if (toins < jb->hist_minbuf[j]) {
00251                /* move over */
00252                memmove(jb->hist_minbuf + j + 1, jb->hist_minbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_minbuf[0]));
00253                /* insert */
00254                jb->hist_minbuf[j] = toins;
00255 
00256                break;
00257             }
00258          }
00259       }
00260 
00261       if (0) { 
00262          int k;
00263          fprintf(stderr, "toins = %ld\n", toins);
00264          fprintf(stderr, "maxbuf =");
00265          for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
00266             fprintf(stderr, "%ld ", jb->hist_maxbuf[k]);
00267          fprintf(stderr, "\nminbuf =");
00268          for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
00269             fprintf(stderr, "%ld ", jb->hist_minbuf[k]);
00270          fprintf(stderr, "\n");
00271       }
00272    }
00273 
00274    jb->hist_maxbuf_valid = 1;
00275 }
00276 
00277 static void history_get(jitterbuf *jb) 
00278 {
00279    long max, min, jitter;
00280    int index;
00281    int count;
00282 
00283    if (!jb->hist_maxbuf_valid) 
00284       history_calc_maxbuf(jb);
00285 
00286    /* count is how many items in history we're examining */
00287    count = (jb->hist_ptr < JB_HISTORY_SZ) ? jb->hist_ptr : JB_HISTORY_SZ;
00288 
00289    /* index is the "n"ths highest/lowest that we'll look for */
00290    index = count * JB_HISTORY_DROPPCT / 100;
00291 
00292    /* sanity checks for index */
00293    if (index > (JB_HISTORY_MAXBUF_SZ - 1)) 
00294       index = JB_HISTORY_MAXBUF_SZ - 1;
00295 
00296 
00297    if (index < 0) {
00298       jb->info.min = 0;
00299       jb->info.jitter = 0;
00300       return;
00301    }
00302 
00303    max = jb->hist_maxbuf[index];
00304    min = jb->hist_minbuf[index];
00305 
00306    jitter = max - min;
00307 
00308    /* these debug stmts compare the difference between looking at the absolute jitter, and the
00309     * values we get by throwing away the outliers */
00310    /*
00311    fprintf(stderr, "[%d] min=%d, max=%d, jitter=%d\n", index, min, max, jitter);
00312    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]);
00313    */
00314 
00315    jb->info.min = min;
00316    jb->info.jitter = jitter;
00317 }
00318 
00319 /* returns 1 if frame was inserted into head of queue, 0 otherwise */
00320 static int queue_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts) 
00321 {
00322    jb_frame *frame;
00323    jb_frame *p;
00324    int head = 0;
00325    long resync_ts = ts - jb->info.resync_offset;
00326 
00327    if ((frame = jb->free)) {
00328       jb->free = frame->next;
00329    } else if (!(frame = ast_malloc(sizeof(*frame)))) {
00330       jb_err("cannot allocate frame\n");
00331       return 0;
00332    }
00333 
00334    jb->info.frames_cur++;
00335 
00336    frame->data = data;
00337    frame->ts = resync_ts;
00338    frame->ms = ms;
00339    frame->type = type;
00340 
00341    /* 
00342     * frames are a circular list, jb-frames points to to the lowest ts, 
00343     * jb->frames->prev points to the highest ts
00344     */
00345 
00346    if (!jb->frames) {  /* queue is empty */
00347       jb->frames = frame;
00348       frame->next = frame;
00349       frame->prev = frame;
00350       head = 1;
00351    } else if (resync_ts < jb->frames->ts) {
00352       frame->next = jb->frames;
00353       frame->prev = jb->frames->prev;
00354 
00355       frame->next->prev = frame;
00356       frame->prev->next = frame;
00357 
00358       /* frame is out of order */
00359       jb->info.frames_ooo++;
00360 
00361       jb->frames = frame;
00362       head = 1;
00363    } else { 
00364       p = jb->frames;
00365 
00366       /* frame is out of order */
00367       if (resync_ts < p->prev->ts) jb->info.frames_ooo++;
00368 
00369       while (resync_ts < p->prev->ts && p->prev != jb->frames) 
00370          p = p->prev;
00371 
00372       frame->next = p;
00373       frame->prev = p->prev;
00374 
00375       frame->next->prev = frame;
00376       frame->prev->next = frame;
00377    }
00378    return head;
00379 }
00380 
00381 static long queue_next(jitterbuf *jb) 
00382 {
00383    if (jb->frames) 
00384       return jb->frames->ts;
00385    else 
00386       return -1;
00387 }
00388 
00389 static long queue_last(jitterbuf *jb) 
00390 {
00391    if (jb->frames) 
00392       return jb->frames->prev->ts;
00393    else 
00394       return -1;
00395 }
00396 
00397 static jb_frame *_queue_get(jitterbuf *jb, long ts, int all) 
00398 {
00399    jb_frame *frame;
00400    frame = jb->frames;
00401 
00402    if (!frame)
00403       return NULL;
00404 
00405    /*jb_warn("queue_get: ASK %ld FIRST %ld\n", ts, frame->ts); */
00406 
00407    if (all || ts >= frame->ts) {
00408       /* remove this frame */
00409       frame->prev->next = frame->next;
00410       frame->next->prev = frame->prev;
00411 
00412       if (frame->next == frame)
00413          jb->frames = NULL;
00414       else
00415          jb->frames = frame->next;
00416 
00417 
00418       /* insert onto "free" single-linked list */
00419       frame->next = jb->free;
00420       jb->free = frame;
00421 
00422       jb->info.frames_cur--;
00423 
00424       /* we return the frame pointer, even though it's on free list, 
00425        * but caller must copy data */
00426       return frame;
00427    } 
00428 
00429    return NULL;
00430 }
00431 
00432 static jb_frame *queue_get(jitterbuf *jb, long ts) 
00433 {
00434    return _queue_get(jb,ts,0);
00435 }
00436 
00437 static jb_frame *queue_getall(jitterbuf *jb) 
00438 {
00439    return _queue_get(jb,0,1);
00440 }
00441 
00442 #if 0
00443 /* some diagnostics */
00444 static void jb_dbginfo(jitterbuf *jb) 
00445 {
00446    if (dbgf == NULL) 
00447       return;
00448 
00449    jb_dbg("\njb info: fin=%ld fout=%ld flate=%ld flost=%ld fdrop=%ld fcur=%ld\n",
00450       jb->info.frames_in, jb->info.frames_out, jb->info.frames_late, jb->info.frames_lost, jb->info.frames_dropped, jb->info.frames_cur);
00451    
00452    jb_dbg("jitter=%ld current=%ld target=%ld min=%ld sil=%d len=%d len/fcur=%ld\n",
00453       jb->info.jitter, jb->info.current, jb->info.target, jb->info.min, jb->info.silence_begin_ts, jb->info.current - jb->info.min, 
00454       jb->info.frames_cur ? (jb->info.current - jb->info.min)/jb->info.frames_cur : -8);
00455    if (jb->info.frames_in > 0) 
00456       jb_dbg("jb info: Loss PCT = %ld%%, Late PCT = %ld%%\n",
00457          jb->info.frames_lost * 100/(jb->info.frames_in + jb->info.frames_lost), 
00458          jb->info.frames_late * 100/jb->info.frames_in);
00459    jb_dbg("jb info: queue %d -> %d.  last_ts %d (queue len: %d) last_ms %d\n",
00460       queue_next(jb), 
00461       queue_last(jb),
00462       jb->info.next_voice_ts, 
00463       queue_last(jb) - queue_next(jb),
00464       jb->info.last_voice_ms);
00465 }
00466 #endif
00467 
00468 #ifdef DEEP_DEBUG
00469 static void jb_chkqueue(jitterbuf *jb) 
00470 {
00471    int i=0;
00472    jb_frame *p = jb->frames;
00473 
00474    if (!p) {
00475       return;
00476    }
00477 
00478    do {
00479       if (p->next == NULL)  {
00480          jb_err("Queue is BROKEN at item [%d]", i);   
00481       }
00482       i++;
00483       p=p->next;
00484    } while (p->next != jb->frames);
00485 }
00486 
00487 static void jb_dbgqueue(jitterbuf *jb) 
00488 {
00489    int i=0;
00490    jb_frame *p = jb->frames;
00491 
00492    jb_dbg("queue: ");
00493 
00494    if (!p) {
00495       jb_dbg("EMPTY\n");
00496       return;
00497    }
00498 
00499    do {
00500       jb_dbg("[%d]=%ld ", i++, p->ts);
00501       p=p->next;
00502    } while (p->next != jb->frames);
00503 
00504    jb_dbg("\n");
00505 }
00506 #endif
00507 
00508 enum jb_return_code jb_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts, long now) 
00509 {
00510    long numts;
00511 
00512    jb_dbg2("jb_put(%x,%x,%ld,%ld,%ld)\n", jb, data, ms, ts, now);
00513 
00514    numts = 0;
00515    if (jb->frames)
00516       numts = jb->frames->prev->ts - jb->frames->ts;
00517 
00518    if (numts >= jb->info.conf.max_jitterbuf) {
00519       if (!jb->dropem) {
00520          ast_debug(1, "Attempting to exceed Jitterbuf max %ld timeslots\n",
00521             jb->info.conf.max_jitterbuf);
00522          jb->dropem = 1;
00523       }
00524       jb->info.frames_dropped++;
00525       return JB_DROP;
00526    } else {
00527       jb->dropem = 0;
00528    }
00529 
00530    if (type == JB_TYPE_VOICE) {
00531       /* presently, I'm only adding VOICE frames to history and drift calculations; mostly because with the
00532        * IAX integrations, I'm sending retransmitted control frames with their awkward timestamps through */
00533       if (history_put(jb,ts,now,ms)) {
00534          jb->info.frames_dropped++;
00535          return JB_DROP;
00536       }
00537    }
00538 
00539    jb->info.frames_in++;
00540 
00541    /* if put into head of queue, caller needs to reschedule */
00542    if (queue_put(jb,data,type,ms,ts)) {
00543       return JB_SCHED;
00544    }
00545    return JB_OK;
00546 }
00547 
00548 
00549 static enum jb_return_code _jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
00550 {
00551    jb_frame *frame;
00552    long diff;
00553    static int dbg_cnt = 0;
00554 
00555    /*if ((now - jb_next(jb)) > 2 * jb->info.last_voice_ms) jb_warn("SCHED: %ld", (now - jb_next(jb))); */
00556    /* get jitter info */
00557    history_get(jb);
00558 
00559    if (dbg_cnt && dbg_cnt % 50 == 0) {
00560       jb_dbg("\n");
00561    }
00562    dbg_cnt++;
00563 
00564    /* target */
00565    jb->info.target = jb->info.jitter + jb->info.min + jb->info.conf.target_extra; 
00566 
00567    /* if a hard clamp was requested, use it */
00568    if ((jb->info.conf.max_jitterbuf) && ((jb->info.target - jb->info.min) > jb->info.conf.max_jitterbuf)) {
00569       jb_dbg("clamping target from %ld to %ld\n", (jb->info.target - jb->info.min), jb->info.conf.max_jitterbuf);
00570       jb->info.target = jb->info.min + jb->info.conf.max_jitterbuf;
00571    }
00572 
00573    diff = jb->info.target - jb->info.current;
00574 
00575    /* jb_warn("diff = %d lms=%d last = %d now = %d\n", diff,  */
00576    /* jb->info.last_voice_ms, jb->info.last_adjustment, now); */
00577 
00578    /* let's work on non-silent case first */
00579    if (!jb->info.silence_begin_ts) { 
00580       /* we want to grow */
00581       if ((diff > 0) && 
00582          /* we haven't grown in the delay length */
00583          (((jb->info.last_adjustment + JB_ADJUST_DELAY) < now) || 
00584          /* we need to grow more than the "length" we have left */
00585          (diff > queue_last(jb)  - queue_next(jb)) ) ) {
00586          /* grow by interp frame length */
00587          jb->info.current += interpl;
00588          jb->info.next_voice_ts += interpl;
00589          jb->info.last_voice_ms = interpl;
00590          jb->info.last_adjustment = now;
00591          jb->info.cnt_contig_interp++;
00592          if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
00593             jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
00594          }
00595          jb_dbg("G");
00596          return JB_INTERP;
00597       }
00598 
00599       frame = queue_get(jb, jb->info.next_voice_ts - jb->info.current);
00600 
00601       /* not a voice frame; just return it. */
00602       if (frame && frame->type != JB_TYPE_VOICE) {
00603          if (frame->type == JB_TYPE_SILENCE) {
00604             jb->info.silence_begin_ts = frame->ts;
00605             jb->info.cnt_contig_interp = 0;
00606          }
00607 
00608          *frameout = *frame;
00609          jb->info.frames_out++;
00610          jb_dbg("o");
00611          return JB_OK;
00612       }
00613 
00614 
00615       /* voice frame is later than expected */
00616       if (frame && frame->ts + jb->info.current < jb->info.next_voice_ts) {
00617          if (frame->ts + jb->info.current > jb->info.next_voice_ts - jb->info.last_voice_ms) {
00618             /* either we interpolated past this frame in the last jb_get */
00619             /* or the frame is still in order, but came a little too quick */ 
00620             *frameout = *frame;
00621             /* reset expectation for next frame */
00622             jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
00623             jb->info.frames_out++;
00624             decrement_losspct(jb);
00625             jb->info.cnt_contig_interp = 0;
00626             jb_dbg("v");
00627             return JB_OK;
00628          } else {
00629             /* voice frame is late */
00630             *frameout = *frame;
00631             jb->info.frames_out++;
00632             decrement_losspct(jb);
00633             jb->info.frames_late++;
00634             jb->info.frames_lost--;
00635             jb_dbg("l");
00636             /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
00637             jb_warninfo(jb); */
00638             return JB_DROP;
00639          }
00640       }
00641 
00642       /* keep track of frame sizes, to allow for variable sized-frames */
00643       if (frame && frame->ms > 0) {
00644          jb->info.last_voice_ms = frame->ms;
00645       }
00646 
00647       /* we want to shrink; shrink at 1 frame / 500ms */
00648       /* unless we don't have a frame, then shrink 1 frame */
00649       /* every 80ms (though perhaps we can shrink even faster */
00650       /* in this case) */
00651       if (diff < -jb->info.conf.target_extra && 
00652          ((!frame && jb->info.last_adjustment + 80 < now) || 
00653          (jb->info.last_adjustment + 500 < now))) {
00654 
00655          jb->info.last_adjustment = now;
00656          jb->info.cnt_contig_interp = 0;
00657 
00658          if (frame) {
00659             *frameout = *frame;
00660             /* shrink by frame size we're throwing out */
00661             jb->info.current -= frame->ms;
00662             jb->info.frames_out++;
00663             decrement_losspct(jb);
00664             jb->info.frames_dropped++;
00665             jb_dbg("s");
00666             return JB_DROP;
00667          } else {
00668             /* shrink by last_voice_ms */
00669             jb->info.current -= jb->info.last_voice_ms;
00670             jb->info.frames_lost++;
00671             increment_losspct(jb);
00672             jb_dbg("S");
00673             return JB_NOFRAME;
00674          }
00675       }
00676 
00677       /* lost frame */
00678       if (!frame) {
00679          /* this is a bit of a hack for now, but if we're close to
00680           * target, and we find a missing frame, it makes sense to
00681           * grow, because the frame might just be a bit late;
00682           * otherwise, we presently get into a pattern where we return
00683           * INTERP for the lost frame, then it shows up next, and we
00684           * throw it away because it's late */
00685          /* I've recently only been able to replicate this using
00686           * iaxclient talking to app_echo on asterisk.  In this case,
00687           * my outgoing packets go through asterisk's (old)
00688           * jitterbuffer, and then might get an unusual increasing delay 
00689           * there if it decides to grow?? */
00690          /* Update: that might have been a different bug, that has been fixed..
00691           * But, this still seemed like a good idea, except that it ended up making a single actual
00692           * lost frame get interpolated two or more times, when there was "room" to grow, so it might
00693           * be a bit of a bad idea overall */
00694          /*if (diff > -1 * jb->info.last_voice_ms) { 
00695             jb->info.current += jb->info.last_voice_ms;
00696             jb->info.last_adjustment = now;
00697             jb_warn("g");
00698             return JB_INTERP;
00699          } */
00700          jb->info.frames_lost++;
00701          increment_losspct(jb);
00702          jb->info.next_voice_ts += interpl;
00703          jb->info.last_voice_ms = interpl;
00704          jb->info.cnt_contig_interp++;
00705          if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
00706             jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
00707          }
00708          jb_dbg("L");
00709          return JB_INTERP;
00710       }
00711 
00712       /* normal case; return the frame, increment stuff */
00713       *frameout = *frame;
00714       jb->info.next_voice_ts += frame->ms;
00715       jb->info.frames_out++;
00716       jb->info.cnt_contig_interp = 0;
00717       decrement_losspct(jb);
00718       jb_dbg("v");
00719       return JB_OK;
00720    } else {     
00721       /* TODO: after we get the non-silent case down, we'll make the
00722        * silent case -- basically, we'll just grow and shrink faster
00723        * here, plus handle next_voice_ts a bit differently */
00724 
00725       /* to disable silent special case altogether, just uncomment this: */
00726       /* jb->info.silence_begin_ts = 0; */
00727 
00728       /* shrink interpl len every 10ms during silence */
00729       if (diff < -jb->info.conf.target_extra &&
00730          jb->info.last_adjustment + 10 <= now) {
00731          jb->info.current -= interpl;
00732          jb->info.last_adjustment = now;
00733       }
00734 
00735       frame = queue_get(jb, now - jb->info.current);
00736       if (!frame) {
00737          return JB_NOFRAME;
00738       } else if (frame->type != JB_TYPE_VOICE) {
00739          /* normal case; in silent mode, got a non-voice frame */
00740          *frameout = *frame;
00741          jb->info.frames_out++;
00742          return JB_OK;
00743       }
00744       if (frame->ts < jb->info.silence_begin_ts) {
00745          /* voice frame is late */
00746          *frameout = *frame;
00747          jb->info.frames_out++;
00748          decrement_losspct(jb);
00749          jb->info.frames_late++;
00750          jb->info.frames_lost--;
00751          jb_dbg("l");
00752          /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
00753          jb_warninfo(jb); */
00754          return JB_DROP;
00755       } else {
00756          /* voice frame */
00757          /* try setting current to target right away here */
00758          jb->info.current = jb->info.target;
00759          jb->info.silence_begin_ts = 0;
00760          jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
00761          jb->info.last_voice_ms = frame->ms;
00762          jb->info.frames_out++;
00763          decrement_losspct(jb);
00764          *frameout = *frame;
00765          jb_dbg("V");
00766          return JB_OK;
00767       }
00768    }
00769 }
00770 
00771 long jb_next(jitterbuf *jb) 
00772 {
00773    if (jb->info.silence_begin_ts) {
00774       if (jb->frames) {
00775          long next = queue_next(jb);
00776          history_get(jb);
00777          /* shrink during silence */
00778          if (jb->info.target - jb->info.current < -jb->info.conf.target_extra)
00779             return jb->info.last_adjustment + 10;
00780          return next + jb->info.target;
00781       }
00782       else 
00783          return JB_LONGMAX;
00784    } else {
00785       return jb->info.next_voice_ts;
00786    }
00787 }
00788 
00789 enum jb_return_code jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
00790 {
00791    enum jb_return_code ret = _jb_get(jb, frameout, now, interpl);
00792 #if 0
00793    static int lastts=0;
00794    int thists = ((ret == JB_OK) || (ret == JB_DROP)) ? frameout->ts : 0;
00795    jb_warn("jb_get(%x,%x,%ld) = %d (%d)\n", jb, frameout, now, ret, thists);
00796    if (thists && thists < lastts) jb_warn("XXXX timestamp roll-back!!!\n");
00797    lastts = thists;
00798 #endif
00799    if (ret == JB_INTERP) 
00800       frameout->ms = jb->info.last_voice_ms;
00801    
00802    return ret;
00803 }
00804 
00805 enum jb_return_code jb_getall(jitterbuf *jb, jb_frame *frameout) 
00806 {
00807    jb_frame *frame;
00808    frame = queue_getall(jb);
00809 
00810    if (!frame) {
00811       return JB_NOFRAME;
00812    }
00813 
00814    *frameout = *frame;
00815    return JB_OK;
00816 }
00817 
00818 
00819 enum jb_return_code jb_getinfo(jitterbuf *jb, jb_info *stats) 
00820 {
00821 
00822    history_get(jb);
00823 
00824    *stats = jb->info;
00825 
00826    return JB_OK;
00827 }
00828 
00829 enum jb_return_code jb_setconf(jitterbuf *jb, jb_conf *conf) 
00830 {
00831    /* take selected settings from the struct */
00832 
00833    jb->info.conf.max_jitterbuf = conf->max_jitterbuf;
00834    jb->info.conf.resync_threshold = conf->resync_threshold;
00835    jb->info.conf.max_contig_interp = conf->max_contig_interp;
00836 
00837    /* -1 indicates use of the default JB_TARGET_EXTRA value */
00838    jb->info.conf.target_extra = ( conf->target_extra == -1 )
00839       ? JB_TARGET_EXTRA
00840       : conf->target_extra
00841       ;
00842       
00843    /* update these to match new target_extra setting */
00844    jb->info.current = jb->info.conf.target_extra;
00845    jb->info.target = jb->info.conf.target_extra;
00846 
00847    return JB_OK;
00848 }
00849 
00850 

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