jitterbuf.c

来自网络的iaxclient的协议栈源码

		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)
{
	jb_dbg2("jb_put(%x,%x,%ld,%ld,%ld)\n", jb, data, ms, ts, now);

	jb->info.frames_in++;

	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
		 */
		if (history_put(jb,ts,now,ms))
			return JB_DROP;
	}

	/* 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;

	/*if ((now - jb_next(jb)) > 2 * jb->info.last_voice_ms) jb_warn("SCHED: %ld", (now - jb_next(jb))); */
	/* get jitter info */
	history_get(jb);


	/* 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 %d to %d\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++;
			/* assume silence instead of continuing to interpolate */
			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) {
			/* track start of silence */
			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");
				/*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
				  jb_warninfo(jb); */
				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++;
			/* assume silence instead of continuing to interpolate */
			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");
			/*jb_warn("\nlate: wanted=%ld, this=%ld, next=%ld\n", jb->info.next_voice_ts - jb->info.current, frame->ts, queue_next(jb));
			  jb_warninfo(jb); */
			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
	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;
}