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