/*
* jitterbuf: an application-independent jitterbuffer
*
* Copyrights:
* Copyright (C) 2004-2005, Horizon Wimba, Inc.
*
* Contributors:
* Steve Kann <stevek@stevek.com>
*
* 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
*/
/*! \file
* \brief
* jitterbuf: an application-independent jitterbuffer
* \ref jitterbuf.c
*/
#ifndef _JITTERBUF_H_
#define _JITTERBUF_H_
#ifdef __cplusplus
extern "C" {
#endif
/*! \name configuration constants
* @{
*/
/*! Number of historical timestamps to use in calculating jitter and drift */
#define JB_HISTORY_SZ 500
/*! what percentage of timestamps should we drop from the history when we examine it;
* this might eventually be something made configurable */
#define JB_HISTORY_DROPPCT 3
/*! the maximum droppct we can handle (say it was configurable). */
#define JB_HISTORY_DROPPCT_MAX 4
/*! the size of the buffer we use to keep the top and botton timestamps for dropping */
#define JB_HISTORY_MAXBUF_SZ JB_HISTORY_SZ * JB_HISTORY_DROPPCT_MAX / 100
/*! amount of additional jitterbuffer adjustment */
#define JB_TARGET_EXTRA 40
/*! ms between growing and shrinking; may not be honored if jitterbuffer runs out of space */
#define JB_ADJUST_DELAY 40
/*! @} */
enum jb_return_code {
/* return codes */
JB_OK, /* 0 */
JB_EMPTY, /* 1 */
JB_NOFRAME, /* 2 */
JB_INTERP, /* 3 */
JB_DROP, /* 4 */
JB_SCHED /* 5 */
};
enum jb_frame_type {
/* frame types */
JB_TYPE_CONTROL, /*!< 0 */
JB_TYPE_VOICE, /*!< 1 */
JB_TYPE_VIDEO, /*!< 2 - reserved */
JB_TYPE_SILENCE /*!< 3 */
};
typedef struct jb_conf {
/* settings */
long max_jitterbuf; /*!< defines a hard clamp to use in setting the jitter buffer delay */
long resync_threshold; /*!< the jb will resync when delay increases to (2 * jitter) + this param */
long max_contig_interp; /*!< the max interp frames to return in a row */
long target_extra ; /*!< amount of additional jitterbuffer adjustment, overrides JB_TARGET_EXTRA */
} jb_conf;
typedef struct jb_info {
jb_conf conf;
/* statistics */
long frames_in; /*!< number of frames input to the jitterbuffer.*/
long frames_out; /*!< number of frames output from the jitterbuffer.*/
long frames_late; /*!< number of frames which were too late, and dropped.*/
long frames_lost; /*!< number of missing frames.*/
long frames_dropped; /*!< number of frames dropped (shrinkage) */
long frames_ooo; /*!< number of frames received out-of-order */
long frames_cur; /*!< number of frames presently in jb, awaiting delivery.*/
long jitter; /*!< jitter measured within current history interval*/
long min; /*!< minimum lateness within current history interval */
long current; /*!< the present jitterbuffer adjustment */
long target; /*!< the target jitterbuffer adjustment */
long losspct; /*!< recent lost frame percentage (* 1000) */
long next_voice_ts; /*!< the ts of the next frame to be read from the jb - in receiver's time */
long last_voice_ms; /*!< the duration of the last voice frame */
long silence_begin_ts; /*!< the time of the last CNG frame, when in silence */
long last_adjustment; /*!< the time of the last adjustment */
long last_delay; /*!< the last now added to history */
long cnt_delay_discont; /*!< the count of discontinuous delays */
long resync_offset; /*!< the amount to offset ts to support resyncs */
long cnt_contig_interp; /*!< the number of contiguous interp frames returned */
} jb_info;
typedef struct jb_frame {
void *data; /* the frame data */
long ts; /* the relative delivery time expected */
long ms; /* the time covered by this frame, in sec/8000 */
enum jb_frame_type type; /* the type of frame */
struct jb_frame *next, *prev;
} jb_frame;
typedef struct jitterbuf {
jb_info info;
/* history */
long history[JB_HISTORY_SZ]; /*!< history */
int hist_ptr; /*!< points to index in history for next entry */
long hist_maxbuf[JB_HISTORY_MAXBUF_SZ]; /*!< a sorted buffer of the max delays (highest first) */
long hist_minbuf[JB_HISTORY_MAXBUF_SZ]; /*!< a sorted buffer of the min delays (lowest first) */
int hist_maxbuf_valid; /*!< are the "maxbuf"/minbuf valid? */
unsigned int dropem:1; /*!< flag to indicate dropping frames (overload) */
jb_frame *frames; /*!< queued frames */
jb_frame *free; /*!< free frames (avoid malloc?) */
} jitterbuf;
/*! \brief new jitterbuf */
jitterbuf * jb_new(void);
/*! \brief destroy jitterbuf */
void jb_destroy(jitterbuf *jb);
/*! \brief reset jitterbuf
* \note The jitterbuffer should be empty before you call this, otherwise
* you will leak queued frames, and some internal structures */
void jb_reset(jitterbuf *jb);
/*!\brief 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
*/
enum jb_return_code jb_put(jitterbuf *jb, void *data, const enum jb_frame_type type, long ms, long ts, long now);
/*! \brief 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_get(jitterbuf *jb, jb_frame *frame, long now, long interpl);
/*! \brief unconditionally get frames from jitterbuf until empty */
enum jb_return_code jb_getall(jitterbuf *jb, jb_frame *frameout);
/*! \brief 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) */
long jb_next(jitterbuf *jb);
/*! \brief get jitterbuf info: only "statistics" may be valid */
enum jb_return_code jb_getinfo(jitterbuf *jb, jb_info *stats);
/*! \brief set jitterbuf conf */
enum jb_return_code jb_setconf(jitterbuf *jb, jb_conf *conf);
typedef void __attribute__((format(printf, 1, 2))) (*jb_output_function_t)(const char *fmt, ...);
void jb_setoutput(jb_output_function_t err, jb_output_function_t warn, jb_output_function_t dbg);
/*! \brief Checks if the given time stamp is late */
int jb_is_late(jitterbuf *jb, long ts);
#ifdef __cplusplus
}
#endif
#endif