jitterbuf: an application-independent jitterbuffer jitterbuf.c More...

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Data Structures
struct	jb_conf
struct	jb_frame
struct	jb_info
struct	jitterbuf
Defines
configuration constants
#define	JB_HISTORY_SZ 500
#define	JB_HISTORY_DROPPCT 3
#define	JB_HISTORY_DROPPCT_MAX 4
#define	JB_HISTORY_MAXBUF_SZ JB_HISTORY_SZ * JB_HISTORY_DROPPCT_MAX / 100
#define	JB_TARGET_EXTRA 40
#define	JB_ADJUST_DELAY 40
Typedefs
typedef struct jb_conf	jb_conf
typedef struct jb_frame	jb_frame
typedef struct jb_info	jb_info
typedef void(*	jb_output_function_t )(const char *fmt,...)
typedef struct jitterbuf	jitterbuf
Enumerations
enum	jb_frame_type { JB_TYPE_CONTROL, JB_TYPE_VOICE, JB_TYPE_VIDEO, JB_TYPE_SILENCE }
enum	jb_return_code { JB_OK, JB_EMPTY, JB_NOFRAME, JB_INTERP, JB_DROP, JB_SCHED }
Functions
void	jb_destroy (jitterbuf *jb)
	destroy jitterbuf
enum jb_return_code	jb_get (jitterbuf jb, jb_frame frame, long now, long interpl)
	get a frame for time now (receiver's time) return value is one of JB_OK: You've got frame! JB_DROP: Here's an audio frame you should just drop. Ask me again for this time.. JB_NOFRAME: There's no frame scheduled for this time. JB_INTERP: Please interpolate an interpl-length frame for this time (either we need to grow, or there was a lost frame) JB_EMPTY: The jb is empty.
enum jb_return_code	jb_getall (jitterbuf jb, jb_frame frameout)
	unconditionally get frames from jitterbuf until empty
enum jb_return_code	jb_getinfo (jitterbuf jb, jb_info stats)
	get jitterbuf info: only "statistics" may be valid
jitterbuf *	jb_new (void)
	new jitterbuf
long	jb_next (jitterbuf *jb)
	when is the next frame due out, in receiver's time (0=EMPTY) This value may change as frames are added (esp non-audio frames)
enum jb_return_code	jb_put (jitterbuf jb, void data, const enum jb_frame_type type, long ms, long ts, long now)
	queue a frame
void	jb_reset (jitterbuf *jb)
	reset jitterbuf
enum jb_return_code	jb_setconf (jitterbuf jb, jb_conf conf)
	set jitterbuf conf
void	jb_setoutput (jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg)

Detailed Description

jitterbuf: an application-independent jitterbuffer jitterbuf.c

Definition in file jitterbuf.h.

Define Documentation

#define JB_ADJUST_DELAY 40

ms between growing and shrinking; may not be honored if jitterbuffer runs out of space

Definition at line 44 of file jitterbuf.h.

Referenced by _jb_get().

#define JB_HISTORY_DROPPCT 3

what percentage of timestamps should we drop from the history when we examine it; this might eventually be something made configurable

Definition at line 36 of file jitterbuf.h.

Referenced by history_get().

#define JB_HISTORY_DROPPCT_MAX 4

the maximum droppct we can handle (say it was configurable).

Definition at line 38 of file jitterbuf.h.

#define JB_HISTORY_MAXBUF_SZ JB_HISTORY_SZ * JB_HISTORY_DROPPCT_MAX / 100

the size of the buffer we use to keep the top and botton timestamps for dropping

Definition at line 40 of file jitterbuf.h.

Referenced by history_calc_maxbuf(), history_get(), and history_put().

#define JB_HISTORY_SZ 500

Number of historical timestamps to use in calculating jitter and drift

Definition at line 33 of file jitterbuf.h.

Referenced by history_calc_maxbuf(), history_get(), and history_put().

#define JB_TARGET_EXTRA 40

amount of additional jitterbuffer adjustment

Definition at line 42 of file jitterbuf.h.

Referenced by jb_reset(), and jb_setconf().

Typedef Documentation

typedef struct jb_conf jb_conf

typedef struct jb_frame jb_frame

typedef struct jb_info jb_info

typedef void(* jb_output_function_t)(const char *fmt,...)

Definition at line 166 of file jitterbuf.h.

typedef struct jitterbuf jitterbuf

Enumeration Type Documentation

enum jb_frame_type

Enumerator:

JB_TYPE_CONTROL	0
JB_TYPE_VOICE	1
JB_TYPE_VIDEO	2 - reserved
JB_TYPE_SILENCE	3

Definition at line 57 of file jitterbuf.h.

                   {
   /* frame types */
   JB_TYPE_CONTROL,  /*!< 0            */
   JB_TYPE_VOICE,    /*!< 1            */
   JB_TYPE_VIDEO,    /*!< 2 - reserved */
   JB_TYPE_SILENCE   /*!< 3            */
};

enum jb_return_code

Enumerator:

JB_OK
JB_EMPTY
JB_NOFRAME
JB_INTERP
JB_DROP
JB_SCHED

Definition at line 47 of file jitterbuf.h.

                    {
   /* return codes */
   JB_OK,            /* 0 */
   JB_EMPTY,         /* 1 */
   JB_NOFRAME,       /* 2 */
   JB_INTERP,        /* 3 */
   JB_DROP,          /* 4 */
   JB_SCHED          /* 5 */
};

Function Documentation

void jb_destroy ( jitterbuf * jb )

destroy jitterbuf

Definition at line 95 of file jitterbuf.c.

References ast_free, jitterbuf::free, jb_dbg2, and jb_frame::next.

Referenced by jb_destroy_adaptive(), and pvt_destructor().

{
   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);
}

enum jb_return_code jb_get	(	jitterbuf *	jb,
		jb_frame *	frame,
		long	now,
		long	interpl
	)

get a frame for time now (receiver's time) return value is one of JB_OK: You've got frame! JB_DROP: Here's an audio frame you should just drop. Ask me again for this time.. JB_NOFRAME: There's no frame scheduled for this time. JB_INTERP: Please interpolate an interpl-length frame for this time (either we need to grow, or there was a lost frame) JB_EMPTY: The jb is empty.

Definition at line 788 of file jitterbuf.c.

References _jb_get(), jitterbuf::info, JB_DROP, JB_INTERP, JB_OK, jb_warn, jb_info::last_voice_ms, jb_frame::ms, and jb_frame::ts.

Referenced by __get_from_jb(), and jb_get_adaptive().

{
   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
	)

unconditionally get frames from jitterbuf until empty

Definition at line 804 of file jitterbuf.c.

References JB_NOFRAME, JB_OK, and queue_getall().

Referenced by complete_transfer(), jb_empty_and_reset_adaptive(), jb_remove_adaptive(), pvt_destructor(), and schedule_delivery().

{
   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
	)

get jitterbuf info: only "statistics" may be valid

Definition at line 818 of file jitterbuf.c.

References history_get(), jitterbuf::info, and JB_OK.

Referenced by ast_cli_netstats(), construct_rr(), handle_cli_iax2_show_channels(), and log_jitterstats().

{

   history_get(jb);

   *stats = jb->info;

   return JB_OK;
}

jitterbuf* jb_new ( void )

new jitterbuf

Definition at line 82 of file jitterbuf.c.

References ast_malloc, jb_dbg2, and jb_reset().

Referenced by jb_create_adaptive(), and new_iax().

{
   jitterbuf *jb;

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

   jb_reset(jb);

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

long jb_next ( jitterbuf * jb )

when is the next frame due out, in receiver's time (0=EMPTY) This value may change as frames are added (esp non-audio frames)

Definition at line 770 of file jitterbuf.c.

References jb_info::conf, jb_info::current, jitterbuf::frames, history_get(), jitterbuf::info, JB_LONGMAX, jb_info::last_adjustment, jb_info::next_voice_ts, queue_next(), jb_info::silence_begin_ts, jb_info::target, and jb_conf::target_extra.

Referenced by __get_from_jb(), jb_next_adaptive(), and update_jbsched().

{
   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_put	(	jitterbuf *	jb,
		void *	data,
		const enum jb_frame_type	type,
		long	ms,
		long	ts,
		long	now
	)

queue a frame

data=frame data, timings (in ms): ms=length of frame (for voice), ts=ts (sender's time) now=now (in receiver's time) return value is one of JB_OK: Frame added. Last call to jb_next() still valid JB_DROP: Drop this frame immediately JB_SCHED: Frame added. Call jb_next() to get a new time for the next frame

Definition at line 507 of file jitterbuf.c.

References ast_debug, jb_info::conf, jitterbuf::dropem, jitterbuf::frames, jb_info::frames_dropped, jb_info::frames_in, history_put(), jitterbuf::info, jb_dbg2, JB_DROP, JB_OK, JB_SCHED, JB_TYPE_VOICE, jb_conf::max_jitterbuf, jb_frame::prev, queue_put(), and jb_frame::ts.

Referenced by jb_put_adaptive(), and schedule_delivery().

{
   long numts;

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

   numts = 0;
   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 JB_DROP;
   } else {
      jb->dropem = 0;
   }

   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)) {
         jb->info.frames_dropped++;
         return JB_DROP;
      }
   }

   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;
}

void jb_reset ( jitterbuf * jb )

reset jitterbuf

Note:: The jitterbuffer should be empty before you call this, otherwise you will leak queued frames, and some internal structures

Definition at line 70 of file jitterbuf.c.

References jb_info::conf, jb_info::current, jitterbuf::info, JB_TARGET_EXTRA, jb_info::silence_begin_ts, jb_info::target, and jb_conf::target_extra.

Referenced by complete_transfer(), jb_empty_and_reset_adaptive(), jb_new(), and schedule_delivery().

{
   /* 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; 
}

enum jb_return_code jb_setconf	(	jitterbuf *	jb,
		jb_conf *	conf
	)

set jitterbuf conf

Definition at line 828 of file jitterbuf.c.

References jb_info::conf, jb_info::current, jitterbuf::info, JB_OK, JB_TARGET_EXTRA, jb_conf::max_contig_interp, jb_conf::max_jitterbuf, jb_conf::resync_threshold, jb_info::target, and jb_conf::target_extra.

Referenced by jb_create_adaptive(), and new_iax().

{
   /* 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;
}

void jb_setoutput	(	jb_output_function_t	err,
		jb_output_function_t	warn,
		jb_output_function_t	dbg
	)

Definition at line 53 of file jitterbuf.c.

Referenced by handle_cli_iax2_set_debug_jb(), and load_module().

{
   errf = err;
   warnf = warn;
   dbgf = dbg;
}

Asterisk developer's documentation

Data Structures

Defines

Typedefs

Enumerations

Functions

Detailed Description

Define Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation