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>
 *
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#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 and free list */
    jb_conf s = jb->info.conf;
    jb_frame *fr = jb->free;
    memset(jb, 0, sizeof(*jb));
    jb->info.conf = s;
    jb->free = fr;
 
    /* 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_calloc(1, 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 (labs(*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 */
                    if (j != JB_HISTORY_MAXBUF_SZ - 1) {
                        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 */
                    if (j != JB_HISTORY_MAXBUF_SZ - 1) {
                        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 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;
}
 
int jb_is_late(jitterbuf *jb, long ts)
{
    return ts + jb->info.current < jb->info.next_voice_ts;
}