1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* 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
*/
#ifndef _JITTERBUF_H_
#define _JITTERBUF_H_
#ifdef __cplusplus
extern "C" {
#endif
/* 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
/* return codes */
#define JB_OK 0
#define JB_EMPTY 1
#define JB_NOFRAME 2
#define JB_INTERP 3
#define JB_DROP 4
/* frame types */
#define JB_TYPE_CONTROL 0
#define JB_TYPE_VOICE 1
#define JB_TYPE_VIDEO 2 /* reserved */
#define JB_TYPE_SILENCE 3
typedef struct jb_info {
/* 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 last_voice_ts; /* the last ts that was read from the jb - in receiver's time */
long last_voice_ms; /* the duration of the last voice frame */
long silence; /* we are presently playing out silence */
long last_adjustment; /* the time of the last adjustment */
/* settings */
long max_jitterbuf; /* defines a hard clamp to use in setting the jitter buffer delay */
} 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 */
int 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? */
jb_frame *frames; /* queued frames */
jb_frame *free; /* free frames (avoid malloc?) */
} jitterbuf;
/* new jitterbuf */
jitterbuf * jb_new(void);
/* destroy jitterbuf */
void jb_destroy(jitterbuf *jb);
/* 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);
/* 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)*/
int jb_put(jitterbuf *jb, void *data, int type, long ms, long ts, long now);
/* 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 audio frame for this time (either we need to grow, or there was a lost frame
* JB_EMPTY: The jb is empty.
*/
int jb_get(jitterbuf *jb, jb_frame *frame, long now);
/* unconditionally get frames from jitterbuf until empty */
int jb_getall(jitterbuf *jb, jb_frame *frameout);
/* 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);
/* get jitterbuf info: only "statistics" may be valid */
int jb_getinfo(jitterbuf *jb, jb_info *stats);
/* set jitterbuf info: only "settings" may be honored */
int jb_setinfo(jitterbuf *jb, jb_info *settings);
typedef void (*jb_output_function_t)(const char *fmt, ...);
void jb_setoutput(jb_output_function_t warn, jb_output_function_t err, jb_output_function_t dbg);
#ifdef __cplusplus
}
#endif
#endif
|
