jitterbuf.c

ppciaxclient softphone

/*
 * jitterbuf: an application-independent jitterbuffer
 *
 * Copyrights:
 * Copyright (C) 2004-2005, Horizon Wimba, Inc.
 *
 * Contributors:
 * Steve Kann <[e-mail]>
 *
 * This program is free software, distributed under the terms of
 * the GNU Lesser (Library) General Public License
 *
 * Copyright on this file is disclaimed to Digium for inclusion in Asterisk
 */

#include "jitterbuf.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* define these here, just for ancient compiler systems */
#define JB_LONGMAX 2147483647L
#define JB_LONGMIN (-JB_LONGMAX - 1L)
#if defined(_MSC_VER)
#define jb_warn(x) ((void)0)
#define jb_err(x) ((void)0)
#define jb_dbg(x) ((void)0)
#else
#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)
#endif

#ifdef DEEP_DEBUG
#define jb_dbg2(...) (dbgf ? dbgf(__VA_ARGS__) : (void)0)
#else
#define jb_dbg2(x) ((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(jitterbuf));
	jb->info.conf = s;

	/* initialize length */
	jb->info.current = jb->info.target = JB_TARGET_EXTRA; 
	jb->info.silence_begin_ts = -1; 
}

jitterbuf * jb_new() 
{
    jitterbuf *jb;


    jb = malloc(sizeof(jitterbuf));
    if(!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;
      free(frame);
      frame = next;
    }

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



/* simple history manipulation */
/* maybe later we can make the history buckets variable size, or something? */
/* drop parameter determines whether we will drop outliers to minimize
 * delay */
#if 0
static int longcmp(const void *a, const void *b) 
{
    return *(long *)a - *(long *)b;
}
#endif

static int history_put(jitterbuf *jb, long ts, long now, long ms) 
{
	long delay = now - (ts - jb->info.resync_offset);
	long threshold = 2 * jb->info.jitter + jb->info.conf.resync_threshold;
	long kicked;

	/* don't add special/negative times to history */
	if (ts <= 0) 
		return 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++;
			if (jb->info.cnt_delay_discont > 3) {
				/* resync the jitterbuffer */
				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 {
				return -1;
			}
		} else {
			jb->info.last_delay = delay;
			jb->info.cnt_delay_discont = 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(long));
		    /* 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(long));
		    /* 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 index;
    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;

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

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


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

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

    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, int type, long ms, long ts) 
{
    jb_frame *frame;
    jb_frame *p;
	int head = 0;
	long resync_ts = ts - jb->info.resync_offset;

    frame = jb->free;
    if(frame) {
	jb->free = frame->next;
    } else {
	frame = malloc(sizeof(jb_frame));
    }

    if(!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(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;