141 lines
4.9 KiB
C
Executable File
141 lines
4.9 KiB
C
Executable File
/*
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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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#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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/* configuration constants */
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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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/* return codes */
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#define JB_OK 0
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#define JB_EMPTY 1
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#define JB_NOFRAME 2
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#define JB_INTERP 3
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#define JB_DROP 4
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/* frame types */
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#define JB_TYPE_CONTROL 0
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#define JB_TYPE_VOICE 1
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#define JB_TYPE_VIDEO 2 /* reserved */
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#define JB_TYPE_SILENCE 3
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typedef struct jb_info {
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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 last_voice_ts; /* the last ts that was 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; /* we are presently playing out silence */
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long last_adjustment; /* the time of the last adjustment */
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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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} 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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int 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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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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/* new jitterbuf */
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jitterbuf * jb_new(void);
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/* destroy jitterbuf */
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void jb_destroy(jitterbuf *jb);
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/* 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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/* queue a frame 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)*/
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int jb_put(jitterbuf *jb, void *data, int type, long ms, long ts, long now);
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/* 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 audio 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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int jb_get(jitterbuf *jb, jb_frame *frame, long now);
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/* unconditionally get frames from jitterbuf until empty */
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int jb_getall(jitterbuf *jb, jb_frame *frameout);
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/* 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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/* get jitterbuf info: only "statistics" may be valid */
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int jb_getinfo(jitterbuf *jb, jb_info *stats);
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/* set jitterbuf info: only "settings" may be honored */
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int jb_setinfo(jitterbuf *jb, jb_info *settings);
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typedef void (*jb_output_function_t)(const char *fmt, ...);
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void jb_setoutput(jb_output_function_t warn, jb_output_function_t err, 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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