jitterbuf.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2004-2005, Horizon Wimba, Inc.
 *
 * Contributors:
 * Steve Kann <stevek@stevek.com>
 *
 * A license has been granted to Digium (via disclaimer) for the use of
 * this code.
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief jitterbuf: an application-independent jitterbuffer
 * \author Steve Kann <stevek@stevek.com>
 *
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 359356 $")

#include "jitterbuf.h"
#include "asterisk/utils.h"

/*! define these here, just for ancient compiler systems */
#define JB_LONGMAX 2147483647L
#define JB_LONGMIN (-JB_LONGMAX - 1L)

#define jb_warn(...) (warnf ? warnf(__VA_ARGS__) : (void)0)
#define jb_err(...) (errf ? errf(__VA_ARGS__) : (void)0)
#define jb_dbg(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)

#ifdef DEEP_DEBUG
#define jb_dbg2(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
#else
#define jb_dbg2(...) ((void)0)
#endif

static jb_output_function_t warnf, errf, dbgf;

void jb_setoutput(jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg) 
{
   errf = err;
   warnf = warn;
   dbgf = dbg;
}

static void increment_losspct(jitterbuf *jb) 
{
   jb->info.losspct = (100000 + 499 * jb->info.losspct)/500;    
}

static void decrement_losspct(jitterbuf *jb) 
{
   jb->info.losspct = (499 * jb->info.losspct)/500;    
}

void jb_reset(jitterbuf *jb) 
{
   /* only save settings */
   jb_conf s = jb->info.conf;
   memset(jb, 0, sizeof(*jb));
   jb->info.conf = s;

   /* initialize length, using the default value */
   jb->info.current = jb->info.target = jb->info.conf.target_extra = JB_TARGET_EXTRA;
   jb->info.silence_begin_ts = -1; 
}

jitterbuf * jb_new() 
{
   jitterbuf *jb;

   if (!(jb = ast_malloc(sizeof(*jb)))) 
      return NULL;

   jb_reset(jb);

   jb_dbg2("jb_new() = %x\n", jb);
   return jb;
}

void jb_destroy(jitterbuf *jb) 
{
   jb_frame *frame; 
   jb_dbg2("jb_destroy(%x)\n", jb);

   /* free all the frames on the "free list" */
   frame = jb->free;
   while (frame != NULL) {
      jb_frame *next = frame->next;
      ast_free(frame);
      frame = next;
   }

   /* free ourselves! */ 
   ast_free(jb);
}

static int check_resync(jitterbuf *jb, long ts, long now, long ms, const enum jb_frame_type type, long *delay)
{
   long numts = 0;
   long threshold = 2 * jb->info.jitter + jb->info.conf.resync_threshold;

   /* Check for overfill of the buffer */
   if (jb->frames) {
      numts = jb->frames->prev->ts - jb->frames->ts;
   }

   if (numts >= (jb->info.conf.max_jitterbuf)) {
      if (!jb->dropem) {
         ast_debug(1, "Attempting to exceed Jitterbuf max %ld timeslots\n",
            jb->info.conf.max_jitterbuf);
         jb->dropem = 1;
      }
      jb->info.frames_dropped++;
      return -1;
   } else {
      jb->dropem = 0;
   }

   /* check for drastic change in delay */
   if (jb->info.conf.resync_threshold != -1) {
      if (abs(*delay - jb->info.last_delay) > threshold) {
         jb->info.cnt_delay_discont++;
         /* resync the jitterbuffer on 3 consecutive discontinuities,
          * or immediately if a control frame */
         if ((jb->info.cnt_delay_discont > 3) || (type == JB_TYPE_CONTROL)) {
            jb->info.cnt_delay_discont = 0;
            jb->hist_ptr = 0;
            jb->hist_maxbuf_valid = 0;
            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);
            jb->info.resync_offset = ts - now;
            jb->info.last_delay = *delay = 0; /* after resync, frame is right on time */
         } else {
            jb->info.frames_dropped++;
            return -1;
         }
      } else {
         jb->info.last_delay = *delay;
         jb->info.cnt_delay_discont = 0;
      }
   }
   return 0;
}

static int history_put(jitterbuf *jb, long ts, long now, long ms, long delay)
{
   long kicked;

   /* don't add special/negative times to history */
   if (ts <= 0)
      return 0;

   kicked = jb->history[jb->hist_ptr % JB_HISTORY_SZ];

   jb->history[(jb->hist_ptr++) % JB_HISTORY_SZ] = delay;

   /* optimization; the max/min buffers don't need to be recalculated, if this packet's
    * entry doesn't change them.  This happens if this packet is not involved, _and_ any packet
    * that got kicked out of the history is also not involved 
    * We do a number of comparisons, but it's probably still worthwhile, because it will usually
    * succeed, and should be a lot faster than going through all 500 packets in history */
   if (!jb->hist_maxbuf_valid)
      return 0;

   /* don't do this until we've filled history 
    * (reduces some edge cases below) */
   if (jb->hist_ptr < JB_HISTORY_SZ)
      goto invalidate;

   /* if the new delay would go into min */
   if (delay < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])
      goto invalidate;

   /* or max.. */
   if (delay > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])
      goto invalidate;

   /* or the kicked delay would be in min */
   if (kicked <= jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1]) 
      goto invalidate;

   if (kicked >= jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1]) 
      goto invalidate;

   /* if we got here, we don't need to invalidate, 'cause this delay didn't 
    * affect things */
   return 0;
   /* end optimization */


invalidate:
   jb->hist_maxbuf_valid = 0;
   return 0;
}

static void history_calc_maxbuf(jitterbuf *jb) 
{
   int i,j;

   if (jb->hist_ptr == 0) 
      return;


   /* initialize maxbuf/minbuf to the latest value */
   for (i=0;i<JB_HISTORY_MAXBUF_SZ;i++) {
/*
 * jb->hist_maxbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
 * jb->hist_minbuf[i] = jb->history[(jb->hist_ptr-1) % JB_HISTORY_SZ];
 */
      jb->hist_maxbuf[i] = JB_LONGMIN;
      jb->hist_minbuf[i] = JB_LONGMAX;
   }

   /* use insertion sort to populate maxbuf */
   /* we want it to be the top "n" values, in order */

   /* start at the beginning, or JB_HISTORY_SZ frames ago */
   i = (jb->hist_ptr > JB_HISTORY_SZ) ? (jb->hist_ptr - JB_HISTORY_SZ) : 0; 

   for (;i<jb->hist_ptr;i++) {
      long toins = jb->history[i % JB_HISTORY_SZ];

      /* if the maxbuf should get this */
      if (toins > jb->hist_maxbuf[JB_HISTORY_MAXBUF_SZ-1])  {

         /* insertion-sort it into the maxbuf */
         for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
            /* found where it fits */
            if (toins > jb->hist_maxbuf[j]) {
               /* move over */
               memmove(jb->hist_maxbuf + j + 1, jb->hist_maxbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_maxbuf[0]));
               /* insert */
               jb->hist_maxbuf[j] = toins;

               break;
            }
         }
      }

      /* if the minbuf should get this */
      if (toins < jb->hist_minbuf[JB_HISTORY_MAXBUF_SZ-1])  {

         /* insertion-sort it into the maxbuf */
         for (j=0;j<JB_HISTORY_MAXBUF_SZ;j++) {
            /* found where it fits */
            if (toins < jb->hist_minbuf[j]) {
               /* move over */
               memmove(jb->hist_minbuf + j + 1, jb->hist_minbuf + j, (JB_HISTORY_MAXBUF_SZ - (j + 1)) * sizeof(jb->hist_minbuf[0]));
               /* insert */
               jb->hist_minbuf[j] = toins;

               break;
            }
         }
      }

      if (0) { 
         int k;
         fprintf(stderr, "toins = %ld\n", toins);
         fprintf(stderr, "maxbuf =");
         for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
            fprintf(stderr, "%ld ", jb->hist_maxbuf[k]);
         fprintf(stderr, "\nminbuf =");
         for (k=0;k<JB_HISTORY_MAXBUF_SZ;k++) 
            fprintf(stderr, "%ld ", jb->hist_minbuf[k]);
         fprintf(stderr, "\n");
      }
   }

   jb->hist_maxbuf_valid = 1;
}

static void history_get(jitterbuf *jb) 
{
   long max, min, jitter;
   int idx;
   int count;

   if (!jb->hist_maxbuf_valid) 
      history_calc_maxbuf(jb);

   /* count is how many items in history we're examining */
   count = (jb->hist_ptr < JB_HISTORY_SZ) ? jb->hist_ptr : JB_HISTORY_SZ;

   /* idx is the "n"ths highest/lowest that we'll look for */
   idx = count * JB_HISTORY_DROPPCT / 100;

   /* sanity checks for idx */
   if (idx > (JB_HISTORY_MAXBUF_SZ - 1)) 
      idx = JB_HISTORY_MAXBUF_SZ - 1;

   if (idx < 0) {
      jb->info.min = 0;
      jb->info.jitter = 0;
      return;
   }

   max = jb->hist_maxbuf[idx];
   min = jb->hist_minbuf[idx];

   jitter = max - min;

   /* these debug stmts compare the difference between looking at the absolute jitter, and the
    * values we get by throwing away the outliers */
   /*
   fprintf(stderr, "[%d] min=%d, max=%d, jitter=%d\n", index, min, max, jitter);
   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]);
   */

   jb->info.min = min;
   jb->info.jitter = jitter;
}

/* returns 1 if frame was inserted into head of queue, 0 otherwise */
static int queue_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts) 
{
   jb_frame *frame;
   jb_frame *p;
   int head = 0;
   long resync_ts = ts - jb->info.resync_offset;

   if ((frame = jb->free)) {
      jb->free = frame->next;
   } else if (!(frame = ast_malloc(sizeof(*frame)))) {
      jb_err("cannot allocate frame\n");
      return 0;
   }

   jb->info.frames_cur++;

   frame->data = data;
   frame->ts = resync_ts;
   frame->ms = ms;
   frame->type = type;

   /* 
    * frames are a circular list, jb-frames points to to the lowest ts, 
    * jb->frames->prev points to the highest ts
    */

   if (!jb->frames) {  /* queue is empty */
      jb->frames = frame;
      frame->next = frame;
      frame->prev = frame;
      head = 1;
   } else if (resync_ts < jb->frames->ts) {
      frame->next = jb->frames;
      frame->prev = jb->frames->prev;

      frame->next->prev = frame;
      frame->prev->next = frame;

      /* frame is out of order */
      jb->info.frames_ooo++;

      jb->frames = frame;
      head = 1;
   } else { 
      p = jb->frames;

      /* frame is out of order */
      if (resync_ts < p->prev->ts) jb->info.frames_ooo++;

      while (resync_ts < p->prev->ts && p->prev != jb->frames) 
         p = p->prev;

      frame->next = p;
      frame->prev = p->prev;

      frame->next->prev = frame;
      frame->prev->next = frame;
   }
   return head;
}

static long queue_next(jitterbuf *jb) 
{
   if (jb->frames) 
      return jb->frames->ts;
   else 
      return -1;
}

static long queue_last(jitterbuf *jb) 
{
   if (jb->frames) 
      return jb->frames->prev->ts;
   else 
      return -1;
}

static jb_frame *_queue_get(jitterbuf *jb, long ts, int all) 
{
   jb_frame *frame;
   frame = jb->frames;

   if (!frame)
      return NULL;

   /*jb_warn("queue_get: ASK %ld FIRST %ld\n", ts, frame->ts); */

   if (all || ts >= frame->ts) {
      /* remove this frame */
      frame->prev->next = frame->next;
      frame->next->prev = frame->prev;

      if (frame->next == frame)
         jb->frames = NULL;
      else
         jb->frames = frame->next;


      /* insert onto "free" single-linked list */
      frame->next = jb->free;
      jb->free = frame;

      jb->info.frames_cur--;

      /* we return the frame pointer, even though it's on free list, 
       * but caller must copy data */
      return frame;
   } 

   return NULL;
}

static jb_frame *queue_get(jitterbuf *jb, long ts) 
{
   return _queue_get(jb,ts,0);
}

static jb_frame *queue_getall(jitterbuf *jb) 
{
   return _queue_get(jb,0,1);
}

#if 0
/* some diagnostics */
static void jb_dbginfo(jitterbuf *jb) 
{
   if (dbgf == NULL) 
      return;

   jb_dbg("\njb info: fin=%ld fout=%ld flate=%ld flost=%ld fdrop=%ld fcur=%ld\n",
      jb->info.frames_in, jb->info.frames_out, jb->info.frames_late, jb->info.frames_lost, jb->info.frames_dropped, jb->info.frames_cur);
   
   jb_dbg("jitter=%ld current=%ld target=%ld min=%ld sil=%d len=%d len/fcur=%ld\n",
      jb->info.jitter, jb->info.current, jb->info.target, jb->info.min, jb->info.silence_begin_ts, jb->info.current - jb->info.min, 
      jb->info.frames_cur ? (jb->info.current - jb->info.min)/jb->info.frames_cur : -8);
   if (jb->info.frames_in > 0) 
      jb_dbg("jb info: Loss PCT = %ld%%, Late PCT = %ld%%\n",
         jb->info.frames_lost * 100/(jb->info.frames_in + jb->info.frames_lost), 
         jb->info.frames_late * 100/jb->info.frames_in);
   jb_dbg("jb info: queue %d -> %d.  last_ts %d (queue len: %d) last_ms %d\n",
      queue_next(jb), 
      queue_last(jb),
      jb->info.next_voice_ts, 
      queue_last(jb) - queue_next(jb),
      jb->info.last_voice_ms);
}
#endif

#ifdef DEEP_DEBUG
static void jb_chkqueue(jitterbuf *jb) 
{
   int i=0;
   jb_frame *p = jb->frames;

   if (!p) {
      return;
   }

   do {
      if (p->next == NULL)  {
         jb_err("Queue is BROKEN at item [%d]", i);   
      }
      i++;
      p=p->next;
   } while (p->next != jb->frames);
}

static void jb_dbgqueue(jitterbuf *jb) 
{
   int i=0;
   jb_frame *p = jb->frames;

   jb_dbg("queue: ");

   if (!p) {
      jb_dbg("EMPTY\n");
      return;
   }

   do {
      jb_dbg("[%d]=%ld ", i++, p->ts);
      p=p->next;
   } while (p->next != jb->frames);

   jb_dbg("\n");
}
#endif

enum jb_return_code jb_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts, long now) 
{
   long delay = now - (ts - jb->info.resync_offset);
   jb_dbg2("jb_put(%x,%x,%ld,%ld,%ld)\n", jb, data, ms, ts, now);

   if (check_resync(jb, ts, now, ms, type, &delay)) {
      return JB_DROP;
   }

   if (type == JB_TYPE_VOICE) {
      /* presently, I'm only adding VOICE frames to history and drift calculations; mostly because with the
       * IAX integrations, I'm sending retransmitted control frames with their awkward timestamps through */
      history_put(jb, ts, now, ms, delay);
   }

   jb->info.frames_in++;

   /* if put into head of queue, caller needs to reschedule */
   if (queue_put(jb,data,type,ms,ts)) {
      return JB_SCHED;
   }
   return JB_OK;
}


static enum jb_return_code _jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
{
   jb_frame *frame;
   long diff;
   static int dbg_cnt = 0;

   /* get jitter info */
   history_get(jb);

   if (dbg_cnt && dbg_cnt % 50 == 0) {
      jb_dbg("\n");
   }
   dbg_cnt++;

   /* target */
   jb->info.target = jb->info.jitter + jb->info.min + jb->info.conf.target_extra; 

   /* if a hard clamp was requested, use it */
   if ((jb->info.conf.max_jitterbuf) && ((jb->info.target - jb->info.min) > jb->info.conf.max_jitterbuf)) {
      jb_dbg("clamping target from %ld to %ld\n", (jb->info.target - jb->info.min), jb->info.conf.max_jitterbuf);
      jb->info.target = jb->info.min + jb->info.conf.max_jitterbuf;
   }

   diff = jb->info.target - jb->info.current;

   /* jb_warn("diff = %d lms=%d last = %d now = %d\n", diff,  */
   /* jb->info.last_voice_ms, jb->info.last_adjustment, now); */

   /* let's work on non-silent case first */
   if (!jb->info.silence_begin_ts) { 
      /* we want to grow */
      if ((diff > 0) && 
         /* we haven't grown in the delay length */
         (((jb->info.last_adjustment + JB_ADJUST_DELAY) < now) || 
         /* we need to grow more than the "length" we have left */
         (diff > queue_last(jb)  - queue_next(jb)) ) ) {
         /* grow by interp frame length */
         jb->info.current += interpl;
         jb->info.next_voice_ts += interpl;
         jb->info.last_voice_ms = interpl;
         jb->info.last_adjustment = now;
         jb->info.cnt_contig_interp++;
         if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
            jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
         }
         jb_dbg("G");
         return JB_INTERP;
      }

      frame = queue_get(jb, jb->info.next_voice_ts - jb->info.current);

      /* not a voice frame; just return it. */
      if (frame && frame->type != JB_TYPE_VOICE) {
         if (frame->type == JB_TYPE_SILENCE) {
            jb->info.silence_begin_ts = frame->ts;
            jb->info.cnt_contig_interp = 0;
         }

         *frameout = *frame;
         jb->info.frames_out++;
         jb_dbg("o");
         return JB_OK;
      }


      /* voice frame is later than expected */
      if (frame && frame->ts + jb->info.current < jb->info.next_voice_ts) {
         if (frame->ts + jb->info.current > jb->info.next_voice_ts - jb->info.last_voice_ms) {
            /* either we interpolated past this frame in the last jb_get */
            /* or the frame is still in order, but came a little too quick */ 
            *frameout = *frame;
            /* reset expectation for next frame */
            jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
            jb->info.frames_out++;
            decrement_losspct(jb);
            jb->info.cnt_contig_interp = 0;
            jb_dbg("v");
            return JB_OK;
         } else {
            /* voice frame is late */
            *frameout = *frame;
            jb->info.frames_out++;
            decrement_losspct(jb);
            jb->info.frames_late++;
            jb->info.frames_lost--;
            jb_dbg("l");
            return JB_DROP;
         }
      }

      /* keep track of frame sizes, to allow for variable sized-frames */
      if (frame && frame->ms > 0) {
         jb->info.last_voice_ms = frame->ms;
      }

      /* we want to shrink; shrink at 1 frame / 500ms */
      /* unless we don't have a frame, then shrink 1 frame */
      /* every 80ms (though perhaps we can shrink even faster */
      /* in this case) */
      if (diff < -jb->info.conf.target_extra && 
         ((!frame && jb->info.last_adjustment + 80 < now) || 
         (jb->info.last_adjustment + 500 < now))) {

         jb->info.last_adjustment = now;
         jb->info.cnt_contig_interp = 0;

         if (frame) {
            *frameout = *frame;
            /* shrink by frame size we're throwing out */
            jb->info.current -= frame->ms;
            jb->info.frames_out++;
            decrement_losspct(jb);
            jb->info.frames_dropped++;
            jb_dbg("s");
            return JB_DROP;
         } else {
            /* shrink by last_voice_ms */
            jb->info.current -= jb->info.last_voice_ms;
            jb->info.frames_lost++;
            increment_losspct(jb);
            jb_dbg("S");
            return JB_NOFRAME;
         }
      }

      /* lost frame */
      if (!frame) {
         /* this is a bit of a hack for now, but if we're close to
          * target, and we find a missing frame, it makes sense to
          * grow, because the frame might just be a bit late;
          * otherwise, we presently get into a pattern where we return
          * INTERP for the lost frame, then it shows up next, and we
          * throw it away because it's late */
         /* I've recently only been able to replicate this using
          * iaxclient talking to app_echo on asterisk.  In this case,
          * my outgoing packets go through asterisk's (old)
          * jitterbuffer, and then might get an unusual increasing delay 
          * there if it decides to grow?? */
         /* Update: that might have been a different bug, that has been fixed..
          * But, this still seemed like a good idea, except that it ended up making a single actual
          * lost frame get interpolated two or more times, when there was "room" to grow, so it might
          * be a bit of a bad idea overall */
         /*if (diff > -1 * jb->info.last_voice_ms) { 
            jb->info.current += jb->info.last_voice_ms;
            jb->info.last_adjustment = now;
            jb_warn("g");
            return JB_INTERP;
         } */
         jb->info.frames_lost++;
         increment_losspct(jb);
         jb->info.next_voice_ts += interpl;
         jb->info.last_voice_ms = interpl;
         jb->info.cnt_contig_interp++;
         if (jb->info.conf.max_contig_interp && jb->info.cnt_contig_interp >= jb->info.conf.max_contig_interp) {
            jb->info.silence_begin_ts = jb->info.next_voice_ts - jb->info.current;
         }
         jb_dbg("L");
         return JB_INTERP;
      }

      /* normal case; return the frame, increment stuff */
      *frameout = *frame;
      jb->info.next_voice_ts += frame->ms;
      jb->info.frames_out++;
      jb->info.cnt_contig_interp = 0;
      decrement_losspct(jb);
      jb_dbg("v");
      return JB_OK;
   } else {     
      /* TODO: after we get the non-silent case down, we'll make the
       * silent case -- basically, we'll just grow and shrink faster
       * here, plus handle next_voice_ts a bit differently */

      /* to disable silent special case altogether, just uncomment this: */
      /* jb->info.silence_begin_ts = 0; */

      /* shrink interpl len every 10ms during silence */
      if (diff < -jb->info.conf.target_extra &&
         jb->info.last_adjustment + 10 <= now) {
         jb->info.current -= interpl;
         jb->info.last_adjustment = now;
      }

      frame = queue_get(jb, now - jb->info.current);
      if (!frame) {
         return JB_NOFRAME;
      } else if (frame->type != JB_TYPE_VOICE) {
         /* normal case; in silent mode, got a non-voice frame */
         *frameout = *frame;
         jb->info.frames_out++;
         return JB_OK;
      }
      if (frame->ts < jb->info.silence_begin_ts) {
         /* voice frame is late */
         *frameout = *frame;
         jb->info.frames_out++;
         decrement_losspct(jb);
         jb->info.frames_late++;
         jb->info.frames_lost--;
         jb_dbg("l");
         return JB_DROP;
      } else {
         /* voice frame */
         /* try setting current to target right away here */
         jb->info.current = jb->info.target;
         jb->info.silence_begin_ts = 0;
         jb->info.next_voice_ts = frame->ts + jb->info.current + frame->ms;
         jb->info.last_voice_ms = frame->ms;
         jb->info.frames_out++;
         decrement_losspct(jb);
         *frameout = *frame;
         jb_dbg("V");
         return JB_OK;
      }
   }
}

long jb_next(jitterbuf *jb) 
{
   if (jb->info.silence_begin_ts) {
      if (jb->frames) {
         long next = queue_next(jb);
         history_get(jb);
         /* shrink during silence */
         if (jb->info.target - jb->info.current < -jb->info.conf.target_extra)
            return jb->info.last_adjustment + 10;
         return next + jb->info.target;
      }
      else 
         return JB_LONGMAX;
   } else {
      return jb->info.next_voice_ts;
   }
}

enum jb_return_code jb_get(jitterbuf *jb, jb_frame *frameout, long now, long interpl) 
{
   enum jb_return_code ret = _jb_get(jb, frameout, now, interpl);
#if 0
   static int lastts=0;
   int thists = ((ret == JB_OK) || (ret == JB_DROP)) ? frameout->ts : 0;
   jb_warn("jb_get(%x,%x,%ld) = %d (%d)\n", jb, frameout, now, ret, thists);
   if (thists && thists < lastts) jb_warn("XXXX timestamp roll-back!!!\n");
   lastts = thists;
#endif
   if (ret == JB_INTERP) 
      frameout->ms = jb->info.last_voice_ms;
   
   return ret;
}

enum jb_return_code jb_getall(jitterbuf *jb, jb_frame *frameout) 
{
   jb_frame *frame;
   frame = queue_getall(jb);

   if (!frame) {
      return JB_NOFRAME;
   }

   *frameout = *frame;
   return JB_OK;
}


enum jb_return_code jb_getinfo(jitterbuf *jb, jb_info *stats) 
{

   history_get(jb);

   *stats = jb->info;

   return JB_OK;
}

enum jb_return_code jb_setconf(jitterbuf *jb, jb_conf *conf) 
{
   /* take selected settings from the struct */

   jb->info.conf.max_jitterbuf = conf->max_jitterbuf;
   jb->info.conf.resync_threshold = conf->resync_threshold;
   jb->info.conf.max_contig_interp = conf->max_contig_interp;

   /* -1 indicates use of the default JB_TARGET_EXTRA value */
   jb->info.conf.target_extra = ( conf->target_extra == -1 )
      ? JB_TARGET_EXTRA
      : conf->target_extra
      ;
      
   /* update these to match new target_extra setting */
   jb->info.current = jb->info.conf.target_extra;
   jb->info.target = jb->info.conf.target_extra;

   return JB_OK;
}