fixedjitterbuf.h File Reference

Jitterbuffering algorithm. More...

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Data Structures
struct	fixed_jb_conf
struct	fixed_jb_frame

Macros
#define	FIXED_JB_RESYNCH_THRESHOLD_DEFAULT   1000
#define	FIXED_JB_SIZE_DEFAULT   200

Enumerations
enum	{ FIXED_JB_OK, FIXED_JB_DROP, FIXED_JB_INTERP, FIXED_JB_NOFRAME }

Functions
void	fixed_jb_destroy (struct fixed_jb *jb)
int	fixed_jb_get (struct fixed_jb *jb, struct fixed_jb_frame *frame, long now, long interpl)
int	fixed_jb_is_late (struct fixed_jb *jb, long ts)
	Checks if the given time stamp is late. More...
struct fixed_jb *	fixed_jb_new (struct fixed_jb_conf *conf)
long	fixed_jb_next (struct fixed_jb *jb)
int	fixed_jb_put (struct fixed_jb *jb, void *data, long ms, long ts, long now)
int	fixed_jb_put_first (struct fixed_jb *jb, void *data, long ms, long ts, long now)
int	fixed_jb_remove (struct fixed_jb *jb, struct fixed_jb_frame *frameout)
void	fixed_jb_set_force_resynch (struct fixed_jb *jb)

Detailed Description

Jitterbuffering algorithm.

Definition in file fixedjitterbuf.h.

Macro Definition Documentation

FIXED_JB_RESYNCH_THRESHOLD_DEFAULT

#define FIXED_JB_RESYNCH_THRESHOLD_DEFAULT   1000

Definition at line 45 of file fixedjitterbuf.h.

Referenced by fixed_jb_new().

FIXED_JB_SIZE_DEFAULT

#define FIXED_JB_SIZE_DEFAULT   200

Definition at line 44 of file fixedjitterbuf.h.

Referenced by fixed_jb_new().

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
FIXED_JB_OK
FIXED_JB_DROP
FIXED_JB_INTERP
FIXED_JB_NOFRAME

Definition at line 35 of file fixedjitterbuf.h.

 {
 FIXED_JB_OK,
 FIXED_JB_DROP,
 FIXED_JB_INTERP,
 FIXED_JB_NOFRAME
};

Function Documentation

fixed_jb_destroy()

void fixed_jb_destroy

(

struct fixed_jb *

jb

)

Definition at line 127 of file fixedjitterbuf.c.

References ASSERT, ast_free, fixed_jb::frames, and NULL.

Referenced by jb_destroy_fixed().

{
 /* jitterbuf MUST be empty before it can be destroyed */
 ASSERT(jb->frames == NULL);

 ast_free(jb);
}

fixed_jb_get()

int fixed_jb_get	(	struct fixed_jb *	jb,
		struct fixed_jb_frame *	frame,
		long	now,
		long	interpl
	)

Definition at line 291 of file fixedjitterbuf.c.

References ASSERT, fixed_jb_frame::delivery, FIXED_JB_DROP, FIXED_JB_INTERP, FIXED_JB_NOFRAME, FIXED_JB_OK, fixed_jb::frames, get_jb_head(), fixed_jb_frame::ms, and fixed_jb::next_delivery.

Referenced by jb_get_fixed().

{
 ASSERT(now >= 0);
 ASSERT(interpl >= 2);

 if (now < jb->next_delivery) {
 /* too early for the next frame */
 return FIXED_JB_NOFRAME;
 }

 /* Is the jb empty? */
 if (!jb->frames) {
 /* should interpolate a frame */
 /* update next */
 jb->next_delivery += interpl;

 return FIXED_JB_INTERP;
 }

 /* Isn't it too late for the first frame available in the jb? */
 if (now > jb->frames->delivery + jb->frames->ms) {
 /* yes - should drop this frame and update next to point the next frame (get_jb_head() does it) */
 get_jb_head(jb, frame);

 return FIXED_JB_DROP;
 }

 /* isn't it too early to play the first frame available? */
 if (now < jb->frames->delivery) {
 /* yes - should interpolate one frame */
 /* update next */
 jb->next_delivery += interpl;

 return FIXED_JB_INTERP;
 }

 /* we have a frame for playing now (get_jb_head() updates next) */
 get_jb_head(jb, frame);

 return FIXED_JB_OK;
}

fixed_jb_is_late()

int fixed_jb_is_late	(	struct fixed_jb *	jb,
		long	ts
	)

Checks if the given time stamp is late.

Definition at line 350 of file fixedjitterbuf.c.

References fixed_jb::delay, fixed_jb::next_delivery, and fixed_jb::rxcore.

Referenced by jb_is_late_fixed().

{
 return jb->rxcore + jb->delay + ts < jb->next_delivery;
}

fixed_jb_new()

struct fixed_jb* fixed_jb_new

(

struct fixed_jb_conf *

conf

)

Definition at line 100 of file fixedjitterbuf.c.

References ast_calloc, fixed_jb::conf, fixed_jb::delay, FIXED_JB_RESYNCH_THRESHOLD_DEFAULT, FIXED_JB_SIZE_DEFAULT, fixed_jb_conf::jbsize, NULL, and fixed_jb_conf::resync_threshold.

Referenced by jb_create_fixed().

{
 struct fixed_jb *jb;

 if (!(jb = ast_calloc(1, sizeof(*jb))))
 return NULL;

 /* First copy our config */
 memcpy(&jb->conf, conf, sizeof(struct fixed_jb_conf));

 /* we don't need the passed config anymore - continue working with the saved one */
 conf = &jb->conf;

 /* validate the configuration */
 if (conf->jbsize < 1)
 conf->jbsize = FIXED_JB_SIZE_DEFAULT;

 if (conf->resync_threshold < 1)
 conf->resync_threshold = FIXED_JB_RESYNCH_THRESHOLD_DEFAULT;

 /* Set the constant delay to the jitterbuf */
 jb->delay = conf->jbsize;

 return jb;
}

fixed_jb_next()

long fixed_jb_next

(

struct fixed_jb *

jb

)

Definition at line 334 of file fixedjitterbuf.c.

References fixed_jb::next_delivery.

Referenced by jb_next_fixed().

{
 return jb->next_delivery;
}

fixed_jb_put()

int fixed_jb_put	(	struct fixed_jb *	jb,
		void *	data,
		long	ms,
		long	ts,
		long	now
	)

Definition at line 197 of file fixedjitterbuf.c.

References alloc_jb_frame(), ASSERT, fixed_jb::conf, fixed_jb_frame::data, fixed_jb::delay, fixed_jb_frame::delivery, FIXED_JB_OK, fixed_jb::force_resynch, fixed_jb::frames, fixed_jb_frame::ms, fixed_jb_frame::next, fixed_jb::next_delivery, NULL, fixed_jb_frame::prev, fixed_jb_conf::resync_threshold, resynch_jb(), fixed_jb::rxcore, fixed_jb::tail, and fixed_jb_frame::ts.

Referenced by fixed_jb_put_first(), jb_put_fixed(), and resynch_jb().

{
 struct fixed_jb_frame *frame, *next, *newframe;
 long delivery;

 /* debug check the validity of the input params */
 ASSERT(data != NULL);
 /* do not allow frames shorter than 2 ms */
 ASSERT(ms >= 2);
 ASSERT(ts >= 0);
 ASSERT(now >= 0);

 delivery = jb->rxcore + jb->delay + ts;

 /* check if the new frame is not too late */
 if (delivery < jb->next_delivery) {
 /* should drop the frame, but let first resynch_jb() check if this is not a jump in ts, or
 the force resynch flag was not set. */
 return resynch_jb(jb, data, ms, ts, now);
 }

 /* what if the delivery time is bigger than next + delay? Seems like a frame for the future.
 However, allow more resync_threshold ms in advance */
 if (delivery > jb->next_delivery + jb->delay + jb->conf.resync_threshold) {
 /* should drop the frame, but let first resynch_jb() check if this is not a jump in ts, or
 the force resynch flag was not set. */
 return resynch_jb(jb, data, ms, ts, now);
 }

 /* find the right place in the frames list, sorted by delivery time */
 frame = jb->tail;
 while (frame && frame->delivery > delivery) {
 frame = frame->prev;
 }

 /* Check if the new delivery time is not covered already by the chosen frame */
 if (frame && (frame->delivery == delivery ||
 delivery < frame->delivery + frame->ms ||
 (frame->next && delivery + ms > frame->next->delivery)))
 {
 /* TODO: Should we check for resynch here? Be careful to do not allow threshold smaller than
 the size of the jb */

 /* should drop the frame, but let first resynch_jb() check if this is not a jump in ts, or
 the force resynch flag was not set. */
 return resynch_jb(jb, data, ms, ts, now);
 }

 /* Reset the force resynch flag */
 jb->force_resynch = 0;

 /* Get a new frame */
 newframe = alloc_jb_frame(jb);
 newframe->data = data;
 newframe->ts = ts;
 newframe->ms = ms;
 newframe->delivery = delivery;

 /* and insert it right on place */
 if (frame) {
 next = frame->next;
 frame->next = newframe;
 if (next) {
 newframe->next = next;
 next->prev = newframe;
 } else {
 /* insert after the last frame - should update tail */
 jb->tail = newframe;
 newframe->next = NULL;
 }
 newframe->prev = frame;

 return FIXED_JB_OK;
 } else if (!jb->frames) {
 /* the frame list is empty or thats just the first frame ever */
 /* tail should also be NULL is that case */
 ASSERT(jb->tail == NULL);
 jb->frames = jb->tail = newframe;
 newframe->next = NULL;
 newframe->prev = NULL;

 return FIXED_JB_OK;
 } else {
 /* insert on a first position - should update frames head */
 newframe->next = jb->frames;
 newframe->prev = NULL;
 jb->frames->prev = newframe;
 jb->frames = newframe;

 return FIXED_JB_OK;
 }
}

fixed_jb_put_first()

int fixed_jb_put_first	(	struct fixed_jb *	jb,
		void *	data,
		long	ms,
		long	ts,
		long	now
	)

Definition at line 185 of file fixedjitterbuf.c.

References fixed_jb::delay, fixed_jb_put(), fixed_jb::next_delivery, fixed_jb::rxcore, and fixed_jb_frame::ts.

Referenced by jb_put_first_fixed(), and resynch_jb().

{
 /* this is our first frame - set the base of the receivers time */
 jb->rxcore = now - ts;

 /* init next for a first time - it should be the time the first frame should be played */
 jb->next_delivery = now + jb->delay;

 /* put the frame */
 return fixed_jb_put(jb, data, ms, ts, now);
}

fixed_jb_remove()

int fixed_jb_remove	(	struct fixed_jb *	jb,
		struct fixed_jb_frame *	frameout
	)

Definition at line 340 of file fixedjitterbuf.c.

References FIXED_JB_NOFRAME, FIXED_JB_OK, fixed_jb::frames, and get_jb_head().

Referenced by jb_empty_and_reset_fixed(), and jb_remove_fixed().

{
 if (!jb->frames)
 return FIXED_JB_NOFRAME;

 get_jb_head(jb, frameout);

 return FIXED_JB_OK;
}

fixed_jb_set_force_resynch()

void fixed_jb_set_force_resynch

(

struct fixed_jb *

jb

)

Definition at line 179 of file fixedjitterbuf.c.

References fixed_jb::force_resynch.

Referenced by jb_force_resynch_fixed().

{
 jb->force_resynch = 1;
}