Sat Sep 16 07:28:09 2006

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 <stdio.h>
00031 #include <stdlib.h>
00032 #include <string.h>
00033 
00034 #include "asterisk.h"
00035 
00036 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 34087 $")
00037 
00038 #include "jitterbuf.h"
00039 
00040 /*! define these here, just for ancient compiler systems */
00041 #define JB_LONGMAX 2147483647L
00042 #define JB_LONGMIN (-JB_LONGMAX - 1L)
00043 
00044 #define jb_warn(...) (warnf ? warnf(__VA_ARGS__) : (void)0)
00045 #define jb_err(...) (errf ? errf(__VA_ARGS__) : (void)0)
00046 #define jb_dbg(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
00047 
00048 #ifdef DEEP_DEBUG
00049 #define jb_dbg2(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
00050 #else
00051 #define jb_dbg2(...) ((void)0)
00052 #endif
00053 
00054 static jb_output_function_t warnf, errf, dbgf;
00055 
00056 void jb_setoutput(jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg) 
00057 {
00058    errf = err;
00059    warnf = warn;
00060    dbgf = dbg;
00061 }
00062 
00063 static void increment_losspct(jitterbuf *jb) 
00064 {
00065    jb->info.losspct = (100000 + 499 * jb->info.losspct)/500;    
00066 }
00067 
00068 static void decrement_losspct(jitterbuf *jb) 
00069 {
00070    jb->info.losspct = (499 * jb->info.losspct)/500;    
00071 }
00072 
00073 void jb_reset(jitterbuf *jb) 
00074 {
00075    /* only save settings */
00076    jb_conf s = jb->info.conf;
00077    memset(jb,0,sizeof(jitterbuf));
00078    jb->info.conf = s;
00079 
00080    /* initialize length */
00081    jb->info.current = jb->info.target = JB_TARGET_EXTRA; 
00082    jb->info.silence_begin_ts = -1; 
00083 }
00084 
00085 jitterbuf * jb_new() 
00086 {
00087    jitterbuf *jb;
00088 
00089 
00090    jb = malloc(sizeof(jitterbuf));
00091    if (!jb) 
00092       return NULL;
00093 
00094    jb_reset(jb);
00095 
00096    jb_dbg2("jb_new() = %x\n", jb);
00097    return jb;
00098 }
00099 
00100 void jb_destroy(jitterbuf *jb) 
00101 {
00102    jb_frame *frame; 
00103    jb_dbg2("jb_destroy(%x)\n", jb);
00104 
00105    /* free all the frames on the "free list" */
00106    frame = jb->free;
00107    while (frame != NULL) {
00108       jb_frame *next = frame->next;
00109       free(frame);
00110       frame = next;
00111    }
00112 
00113    /* free ourselves! */ 
00114    free(jb);
00115 }
00116 
00117 
00118 
00119 #if 0
00120 static int longcmp(const void *a, const void *b) 
00121 {
00122    return *(long *)a - *(long *)b;
00123 }
00124 #endif
00125 
00126 /*!   \brief simple history manipulation 
00127    \note maybe later we can make the history buckets variable size, or something? */
00128 /* drop parameter determines whether we will drop outliers to minimize
00129  * delay */
00130 static int history_put(jitterbuf *jb, long ts, long now, long ms) 
00131 {
00132    long delay = now - (ts - jb->info.resync_offset);
00133    long threshold = 2 * jb->info.jitter + jb->info.conf.resync_threshold;
00134    long kicked;
00135 
00136    /* don't add special/negative times to history */
00137    if (ts <= 0) 
00138       return 0;
00139 
00140    /* check for drastic change in delay */
00141    if (jb->info.conf.resync_threshold != -1) {
00142       if (abs(delay - jb->info.last_delay) > threshold) {
00143          jb->info.cnt_delay_discont++;
00144          if (jb->info.cnt_delay_discont > 3) {
00145             /* resync the jitterbuffer */
00146             jb->info.cnt_delay_discont = 0;
00147             jb->hist_ptr = 0;
00148             jb->hist_maxbuf_valid = 0;
00149 
00150             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);
00151             jb->info.resync_offset = ts - now;
00152             jb->info.last_delay = delay = 0; /* after resync, frame is right on time */
00153          } else {
00154             return -1;
00155          }
00156       } else {
00157          jb->info.last_delay = delay;
00158          jb->info.cnt_delay_discont = 0;
00159       }
00160    }
00161 
00162    kicked = jb->history[jb->hist_ptr % JB_HISTORY_SZ];
00163 
00164    jb->history[(jb->hist_ptr++) % JB_HISTORY_SZ] = delay;
00165 
00166    /* optimization; the max/min buffers don't need to be recalculated, if this packet's
00167     * entry doesn't change them.  This happens if this packet is not involved, _and_ any packet
00168     * that got kicked out of the history is also not involved 
00169     * We do a number of comparisons, but it's probably still worthwhile, because it will usually
00170     * succeed, and should be a lot faster than going through all 500 packets in history */
00171    if (!jb->hist_maxbuf_valid)
00172       return 0;
00173 
00174    /* don't do this until we've filled history 
00175     * (reduces some edge cases below) */
00176    if (jb->hist_ptr < JB_HISTORY_SZ)
00177       goto invalidate;
00178 
00179    /* if the new delay would go into min */
00180    if (delay < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])
00181       goto invalidate;
00182     
00183    /* or max.. */
00184    if (delay > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])
00185       goto invalidate;
00186 
00187    /* or the kicked delay would be in min */
00188    if (kicked <= jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1]) 
00189       goto invalidate;
00190 
00191    if (kicked >= jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1]) 
00192       goto invalidate;
00193 
00194    /* if we got here, we don't need to invalidate, 'cause this delay didn't 
00195     * affect things */
00196    return 0;
00197    /* end optimization */
00198 
00199 
00200 invalidate:
00201    jb->hist_maxbuf_valid = 0;
00202    return 0;
00203 }
00204 
00205 static void history_calc_maxbuf(jitterbuf *jb) 
00206 {
00207    int i,j;
00208 
00209    if (jb->hist_ptr == 0) 
00210       return;
00211 
00212 
00213    /* initialize maxbuf/minbuf to the latest value */
00214    for (i=0;i<JB_HISTORY_MAXBUF_SZ;i++) {
00215 /*
00216  * jb->hist_maxbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
00217  * jb->hist_minbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
00218  */
00219       jb->hist_maxbuf[i] = JB_LONGMIN;
00220       jb->hist_minbuf[i] = JB_LONGMAX;
00221    }
00222 
00223    /* use insertion sort to populate maxbuf */
00224    /* we want it to be the top "n" values, in order */
00225 
00226    /* start at the beginning, or JB_HISTORY_SZ frames ago */
00227    i = (jb->hist_ptr > JB_HISTORY_SZ) ? (jb->hist_ptr - JB_HISTORY_SZ) : 0; 
00228 
00229    for (;i<jb->hist_ptr;i++) {
00230       long toins = jb->history[i % JB_HISTORY_SZ];
00231 
00232       /* if the maxbuf should get this */
00233       if (toins > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])  {
00234 
00235          /* insertion-sort it into the maxbuf */
00236          for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
00237             /* found where it fits */
00238             if (toins > jb->hist_maxbuf[j]) {
00239                /* move over */
00240                memmove(jb->hist_maxbuf+j+1,jb->hist_maxbuf+j, (JB_HISTORY_MAXBUF_SZ-(j+1)) * sizeof(long));
00241                /* insert */
00242                jb->hist_maxbuf[j] = toins;
00243 
00244                break;
00245             }
00246          }
00247       }
00248 
00249       /* if the minbuf should get this */
00250       if (toins < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])  {
00251 
00252          /* insertion-sort it into the maxbuf */
00253          for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
00254             /* found where it fits */
00255             if (toins < jb->hist_minbuf[j]) {
00256                /* move over */
00257                memmove(jb->hist_minbuf+j+1,jb->hist_minbuf+j, (JB_HISTORY_MAXBUF_SZ-(j+1)) * sizeof(long));
00258                /* insert */
00259                jb->hist_minbuf[j] = toins;
00260 
00261                break;
00262             }
00263          }
00264       }
00265 
00266       if (0) { 
00267          int k;
00268          fprintf(stderr, "toins = %ld\n", toins);
00269          fprintf(stderr, "maxbuf =");
00270          for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
00271             fprintf(stderr, "%ld ", jb->hist_maxbuf[k]);
00272          fprintf(stderr, "\nminbuf =");
00273          for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
00274             fprintf(stderr, "%ld ", jb->hist_minbuf[k]);
00275          fprintf(stderr, "\n");
00276       }
00277    }
00278 
00279    jb->hist_maxbuf_valid = 1;
00280 }
00281 
00282 static void history_get(jitterbuf *jb) 
00283 {
00284    long max, min, jitter;
00285    int index;
00286    int count;
00287 
00288    if (!jb->hist_maxbuf_valid) 
00289       history_calc_maxbuf(jb);
00290 
00291    /* count is how many items in history we're examining */
00292    count = (jb->hist_ptr < JB_HISTORY_SZ) ? jb->hist_ptr : JB_HISTORY_SZ;
00293 
00294    /* index is the "n"ths highest/lowest that we'll look for */
00295    index = count * JB_HISTORY_DROPPCT / 100;
00296 
00297    /* sanity checks for index */
00298    if (index > (JB_HISTORY_MAXBUF_SZ - 1)) 
00299       index = JB_HISTORY_MAXBUF_SZ - 1;
00300 
00301 
00302    if (index < 0) {
00303       jb->info.min = 0;
00304       jb->info.jitter = 0;
00305       return;
00306    }
00307 
00308    max = jb->hist_maxbuf[index];
00309    min = jb->hist_minbuf[index];
00310 
00311    jitter = max - min;
00312 
00313    /* these debug stmts compare the difference between looking at the absolute jitter, and the
00314     * values we get by throwing away the outliers */
00315    /*
00316    fprintf(stderr, "[%d] min=%d, max=%d, jitter=%d\n", index, min, max, jitter);
00317    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]);
00318    */
00319 
00320    jb->info.min = min;
00321    jb->info.jitter = jitter;
00322 }
00323 
00324 /* returns 1 if frame was inserted into head of queue, 0 otherwise */
00325 static int queue_put(jitterbuf *jb, void *data, int type, long ms, long ts) 
00326 {
00327    jb_frame *frame;
00328    jb_frame *p;
00329    int head = 0;
00330    long resync_ts = ts - jb->info.resync_offset;
00331 
00332    frame = jb->free;
00333    if (frame) {
00334       jb->free = frame->next;
00335    } else {
00336       frame = malloc(sizeof(jb_frame));
00337    }
00338 
00339    if (!frame) {
00340       jb_err("cannot allocate frame\n");
00341       return 0;
00342    }
00343 
00344    jb->info.frames_cur++;
00345 
00346    frame->data = data;
00347    frame->ts = resync_ts;
00348    frame->ms = ms;
00349    frame->type = type;
00350 
00351    /* 
00352     * frames are a circular list, jb-frames points to to the lowest ts, 
00353     * jb->frames->prev points to the highest ts
00354     */
00355 
00356    if (!jb->frames) {  /* queue is empty */
00357       jb->frames = frame;
00358       frame->next = frame;
00359       frame->prev = frame;
00360       head = 1;
00361    } else if (resync_ts < jb->frames->ts) {
00362       frame->next = jb->frames;
00363       frame->prev = jb->frames->prev;
00364 
00365       frame->next->prev = frame;
00366       frame->prev->next = frame;
00367 
00368       /* frame is out of order */
00369       jb->info.frames_ooo++;
00370 
00371       jb->frames = frame;
00372       head = 1;
00373    } else { 
00374       p = jb->frames;
00375 
00376       /* frame is out of order */
00377       if (resync_ts < p->prev->ts) jb->info.frames_ooo++;
00378 
00379       while (resync_ts < p->prev->ts && p->prev != jb->frames) 
00380          p = p->prev;
00381 
00382       frame->next = p;
00383       frame->prev = p->prev;
00384 
00385       frame->next->prev = frame;
00386       frame->prev->next = frame;
00387    }
00388    return head;
00389 }
00390 
00391 static long queue_next(jitterbuf *jb) 
00392 {
00393    if (jb->frames) 
00394       return jb->frames->ts;
00395    else 
00396       return -1;
00397 }
00398 
00399 static long queue_last(jitterbuf *jb) 
00400 {
00401    if (jb->frames) 
00402       return jb->frames->prev->ts;
00403    else 
00404       return -1;
00405 }
00406 
00407 static jb_frame *_queue_get(jitterbuf *jb, long ts, int all) 
00408 {
00409    jb_frame *frame;
00410    frame = jb->frames;
00411 
00412    if (!frame)
00413       return NULL;
00414 
00415    /*jb_warn("queue_get: ASK %ld FIRST %ld\n", ts, frame->ts); */
00416 
00417    if (all || ts >= frame->ts) {
00418       /* remove this frame */
00419       frame->prev->next = frame->next;
00420       frame->next->prev = frame->prev;
00421 
00422       if (frame->next == frame)
00423          jb->frames = NULL;
00424       else
00425          jb->frames = frame->next;
00426 
00427 
00428       /* insert onto "free" single-linked list */
00429       frame->next = jb->free;
00430       jb->free = frame;
00431 
00432       jb->info.frames_cur--;
00433 
00434       /* we return the frame pointer, even though it's on free list, 
00435        * but caller must copy data */
00436       return frame;
00437    } 
00438 
00439    return NULL;
00440 }
00441 
00442 static jb_frame *queue_get(jitterbuf *jb, long ts) 
00443 {
00444    return _queue_get(jb,ts,0);
00445 }
00446 
00447 static jb_frame *queue_getall(jitterbuf *jb) 
00448 {
00449    return _queue_get(jb,0,1);
00450 }
00451 
00452 #if 0
00453 /* some diagnostics */
00454 static void jb_dbginfo(jitterbuf *jb) 
00455 {
00456    if (dbgf == NULL) 
00457       return;
00458 
00459    jb_dbg("\njb info: fin=%ld fout=%ld flate=%ld flost=%ld fdrop=%ld fcur=%ld\n",
00460       jb->info.frames_in, jb->info.frames_out, jb->info.frames_late, jb->info.frames_lost, jb->info.frames_dropped, jb->info.frames_cur);
00461    
00462    jb_dbg("jitter=%ld current=%ld target=%ld min=%ld sil=%d len=%d len/fcur=%ld\n",
00463       jb->info.jitter, jb->info.current, jb->info.target, jb->info.min, jb->info.silence_begin_ts, jb->info.current - jb->info.min, 
00464       jb->info.frames_cur ? (jb->info.current - jb->info.min)/jb->info.frames_cur : -8);
00465    if (jb->info.frames_in > 0) 
00466       jb_dbg("jb info: Loss PCT = %ld%%, Late PCT = %ld%%\n",
00467          jb->info.frames_lost * 100/(jb->info.frames_in + jb->info.frames_lost), 
00468          jb->info.frames_late * 100/jb->info.frames_in);
00469    jb_dbg("jb info: queue %d -> %d.  last_ts %d (queue len: %d) last_ms %d\n",
00470       queue_next(jb), 
00471       queue_last(jb),
00472       jb->info.next_voice_ts, 
00473       queue_last(jb) - queue_next(jb),
00474       jb->info.last_voice_ms);
00475 }
00476 #endif
00477 
00478 #ifdef DEEP_DEBUG
00479 static void jb_chkqueue(jitterbuf *jb) 
00480 {
00481    int i=0;
00482    jb_frame *p = jb->frames;
00483 
00484    if (!p) {
00485       return;
00486    }
00487 
00488    do {
00489       if (p->next == NULL)  {
00490          jb_err("Queue is BROKEN at item [%d]", i);   
00491       }
00492       i++;
00493       p=p->next;
00494    } while (p->next != jb->frames);
00495 }
00496 
00497 static void jb_dbgqueue(jitterbuf *jb) 
00498 {
00499    int i=0;
00500    jb_frame *p = jb->frames;
00501 
00502    jb_dbg("queue: ");
00503 
00504    if (!p) {
00505       jb_dbg("EMPTY\n");
00506       return;
00507    }
00508 
00509    do {
00510       jb_dbg("[%d]=%ld ", i++, p->ts);
00511       p=p->next;
00512    } while (p->next != jb->frames);
00513 
00514    jb_dbg("\n");
00515 }
00516 #endif
00517 
00518 int jb_put(jitterbuf *jb, void *data, int type, long ms, long ts, long now) 
00519 {
00520    jb_dbg2("jb_put(%x,%x,%ld,%ld,%ld)\n", jb, data, ms, ts, now);
00521 
00522    jb->info.frames_in++;
00523 
00524    if (type == JB_TYPE_VOICE) {
00525       /* presently, I'm only adding VOICE frames to history and drift calculations; mostly because with the
00526        * IAX integrations, I'm sending retransmitted control frames with their awkward timestamps through */
00527       if (history_put(jb,ts,now,ms))
00528          return JB_DROP;
00529    }
00530 
00531    /* if put into head of queue, caller needs to reschedule */
00532    if (queue_put(jb,data,type,ms,ts)) {
00533       return JB_SCHED;
00534    }
00535    return JB_OK;
00536 }
00537 
00538 
00539 static int _jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
00540 {
00541    jb_frame *frame;
00542    long diff;
00543    static int dbg_cnt = 0;
00544 
00545    /*if ((now - jb_next(jb)) > 2 * jb->info.last_voice_ms) jb_warn("SCHED: %ld", (now - jb_next(jb))); */
00546    /* get jitter info */
00547    history_get(jb);
00548 
00549    if (dbg_cnt && dbg_cnt % 50 == 0) {
00550       jb_dbg("\n");
00551    }
00552    dbg_cnt++;
00553 
00554    /* target */
00555    jb->info.target = jb->info.jitter + jb->info.min + JB_TARGET_EXTRA; 
00556 
00557    /* if a hard clamp was requested, use it */
00558    if ((jb->info.conf.max_jitterbuf) && ((jb->info.target - jb->info.min) > jb->info.conf.max_jitterbuf)) {
00559       jb_dbg("clamping target from %d to %d\n", (jb->info.target - jb->info.min), jb->info.conf.max_jitterbuf);
00560       jb->info.target = jb->info.min + jb->info.conf.max_jitterbuf;
00561    }
00562 
00563    diff = jb->info.target - jb->info.current;
00564 
00565    /* jb_warn("diff = %d lms=%d last = %d now = %d\n", diff,  */
00566    /* jb->info.last_voice_ms, jb->info.last_adjustment, now); */
00567 
00568    /* let's work on non-silent case first */
00569    if (!jb->info.silence_begin_ts) { 
00570       /* we want to grow */
00571       if ((diff > 0) && 
00572          /* we haven't grown in the delay length */
00573          (((jb->info.last_adjustment + JB_ADJUST_DELAY) < now) || 
00574          /* we need to grow more than the "length" we have left */
00575          (diff > queue_last(jb)  - queue_next(jb)) ) ) {
00576          /* grow by interp frame length */
00577          jb->info.current += interpl;
00578          jb->info.next_voice_ts += interpl;
00579          jb->info.last_voice_ms = interpl;
00580          jb->info.last_adjustment = now;
00581          jb->info.cnt_contig_interp++;
00582          if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
00583             jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
00584          }
00585          jb_dbg("G");
00586          return JB_INTERP;
00587       }
00588 
00589       frame = queue_get(jb, jb->info.next_voice_ts - jb->info.current);
00590 
00591       /* not a voice frame; just return it. */
00592       if (frame && frame->type != JB_TYPE_VOICE) {
00593          if (frame->type == JB_TYPE_SILENCE) {
00594             jb->info.silence_begin_ts = frame->ts;
00595             jb->info.cnt_contig_interp = 0;
00596          }
00597 
00598          *frameout = *frame;
00599          jb->info.frames_out++;
00600          jb_dbg("o");
00601          return JB_OK;
00602       }
00603 
00604 
00605       /* voice frame is later than expected */
00606       if (frame && frame->ts + jb->info.current < jb->info.next_voice_ts) {
00607          if (frame->ts + jb->info.current > jb->info.next_voice_ts - jb->info.last_voice_ms) {
00608             /* either we interpolated past this frame in the last jb_get */
00609             /* or the frame is still in order, but came a little too quick */ 
00610             *frameout = *frame;
00611             /* reset expectation for next frame */
00612             jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
00613             jb->info.frames_out++;
00614             decrement_losspct(jb);
00615             jb->info.cnt_contig_interp = 0;
00616             jb_dbg("v");
00617             return JB_OK;
00618          } else {
00619             /* voice frame is late */
00620             *frameout = *frame;
00621             jb->info.frames_out++;
00622             decrement_losspct(jb);
00623             jb->info.frames_late++;
00624             jb->info.frames_lost--;
00625             jb_dbg("l");
00626             /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
00627             jb_warninfo(jb); */
00628             return JB_DROP;
00629          }
00630       }
00631 
00632       /* keep track of frame sizes, to allow for variable sized-frames */
00633       if (frame && frame->ms > 0) {
00634          jb->info.last_voice_ms = frame->ms;
00635       }
00636 
00637       /* we want to shrink; shrink at 1 frame / 500ms */
00638       /* unless we don't have a frame, then shrink 1 frame */
00639       /* every 80ms (though perhaps we can shrink even faster */
00640       /* in this case) */
00641       if (diff < -JB_TARGET_EXTRA && 
00642          ((!frame && jb->info.last_adjustment + 80 < now) || 
00643          (jb->info.last_adjustment + 500 < now))) {
00644 
00645          jb->info.last_adjustment = now;
00646          jb->info.cnt_contig_interp = 0;
00647 
00648          if (frame) {
00649             *frameout = *frame;
00650             /* shrink by frame size we're throwing out */
00651             jb->info.current -= frame->ms;
00652             jb->info.frames_out++;
00653             decrement_losspct(jb);
00654             jb->info.frames_dropped++;
00655             jb_dbg("s");
00656             return JB_DROP;
00657          } else {
00658             /* shrink by last_voice_ms */
00659             jb->info.current -= jb->info.last_voice_ms;
00660             jb->info.frames_lost++;
00661             increment_losspct(jb);
00662             jb_dbg("S");
00663             return JB_NOFRAME;
00664          }
00665       }
00666 
00667       /* lost frame */
00668       if (!frame) {
00669          /* this is a bit of a hack for now, but if we're close to
00670           * target, and we find a missing frame, it makes sense to
00671           * grow, because the frame might just be a bit late;
00672           * otherwise, we presently get into a pattern where we return
00673           * INTERP for the lost frame, then it shows up next, and we
00674           * throw it away because it's late */
00675          /* I've recently only been able to replicate this using
00676           * iaxclient talking to app_echo on asterisk.  In this case,
00677           * my outgoing packets go through asterisk's (old)
00678           * jitterbuffer, and then might get an unusual increasing delay 
00679           * there if it decides to grow?? */
00680          /* Update: that might have been a different bug, that has been fixed..
00681           * But, this still seemed like a good idea, except that it ended up making a single actual
00682           * lost frame get interpolated two or more times, when there was "room" to grow, so it might
00683           * be a bit of a bad idea overall */
00684          /*if (diff > -1 * jb->info.last_voice_ms) { 
00685             jb->info.current += jb->info.last_voice_ms;
00686             jb->info.last_adjustment = now;
00687             jb_warn("g");
00688             return JB_INTERP;
00689          } */
00690          jb->info.frames_lost++;
00691          increment_losspct(jb);
00692          jb->info.next_voice_ts += interpl;
00693          jb->info.last_voice_ms = interpl;
00694          jb->info.cnt_contig_interp++;
00695          if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
00696             jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
00697          }
00698          jb_dbg("L");
00699          return JB_INTERP;
00700       }
00701 
00702       /* normal case; return the frame, increment stuff */
00703       *frameout = *frame;
00704       jb->info.next_voice_ts += frame->ms;
00705       jb->info.frames_out++;
00706       jb->info.cnt_contig_interp = 0;
00707       decrement_losspct(jb);
00708       jb_dbg("v");
00709       return JB_OK;
00710    } else {     
00711       /* TODO: after we get the non-silent case down, we'll make the
00712        * silent case -- basically, we'll just grow and shrink faster
00713        * here, plus handle next_voice_ts a bit differently */
00714       
00715       /* to disable silent special case altogether, just uncomment this: */
00716       /* jb->info.silence_begin_ts = 0; */
00717 
00718       /* shrink interpl len every 10ms during silence */
00719       if (diff < -JB_TARGET_EXTRA &&
00720          jb->info.last_adjustment + 10 <= now) {
00721          jb->info.current -= interpl;
00722          jb->info.last_adjustment = now;
00723       }
00724 
00725       frame = queue_get(jb, now - jb->info.current);
00726       if (!frame) {
00727          return JB_NOFRAME;
00728       } else if (frame->type != JB_TYPE_VOICE) {
00729          /* normal case; in silent mode, got a non-voice frame */
00730          *frameout = *frame;
00731          jb->info.frames_out++;
00732          return JB_OK;
00733       }
00734       if (frame->ts < jb->info.silence_begin_ts) {
00735          /* voice frame is late */
00736          *frameout = *frame;
00737          jb->info.frames_out++;
00738          decrement_losspct(jb);
00739          jb->info.frames_late++;
00740          jb->info.frames_lost--;
00741          jb_dbg("l");
00742          /*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
00743          jb_warninfo(jb); */
00744          return JB_DROP;
00745       } else {
00746          /* voice frame */
00747          /* try setting current to target right away here */
00748          jb->info.current = jb->info.target;
00749          jb->info.silence_begin_ts = 0;
00750          jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
00751          jb->info.last_voice_ms = frame->ms;
00752          jb->info.frames_out++;
00753          decrement_losspct(jb);
00754          *frameout = *frame;
00755          jb_dbg("V");
00756          return JB_OK;
00757       }
00758    }
00759 }
00760 
00761 long jb_next(jitterbuf *jb) 
00762 {
00763    if (jb->info.silence_begin_ts) {
00764       long next = queue_next(jb);
00765       if (next > 0) { 
00766          history_get(jb);
00767          /* shrink during silence */
00768          if (jb->info.target - jb->info.current < -JB_TARGET_EXTRA)
00769             return jb->info.last_adjustment + 10;
00770          return next + jb->info.target;
00771       }
00772       else 
00773          return JB_LONGMAX;
00774    } else {
00775       return jb->info.next_voice_ts;
00776    }
00777 }
00778 
00779 int jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
00780 {
00781    int ret = _jb_get(jb,frameout,now,interpl);
00782 #if 0
00783    static int lastts=0;
00784    int thists = ((ret == JB_OK) || (ret == JB_DROP)) ? frameout->ts : 0;
00785    jb_warn("jb_get(%x,%x,%ld) = %d (%d)\n", jb, frameout, now, ret, thists);
00786    if (thists && thists < lastts) jb_warn("XXXX timestamp roll-back!!!\n");
00787    lastts = thists;
00788 #endif
00789    if(ret == JB_INTERP) 
00790       frameout->ms = jb->info.last_voice_ms;
00791    
00792    return ret;
00793 }
00794 
00795 int jb_getall(jitterbuf *jb, jb_frame *frameout) 
00796 {
00797    jb_frame *frame;
00798    frame = queue_getall(jb);
00799 
00800    if (!frame) {
00801       return JB_NOFRAME;
00802    }
00803 
00804    *frameout = *frame;
00805    return JB_OK;
00806 }
00807 
00808 
00809 int jb_getinfo(jitterbuf *jb, jb_info *stats) 
00810 {
00811 
00812    history_get(jb);
00813 
00814    *stats = jb->info;
00815 
00816    return JB_OK;
00817 }
00818 
00819 int jb_setconf(jitterbuf *jb, jb_conf *conf) 
00820 {
00821    /* take selected settings from the struct */
00822 
00823    jb->info.conf.max_jitterbuf = conf->max_jitterbuf;
00824    jb->info.conf.resync_threshold = conf->resync_threshold;
00825    jb->info.conf.max_contig_interp = conf->max_contig_interp;
00826 
00827    return JB_OK;
00828 }
00829 
00830 

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