1 files changed, 140 insertions, 0 deletions
diff --git a/jitterbuf.h b/jitterbuf.h
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--- /dev/null
+++ b/jitterbuf.h
@@ -0,0 +1,140 @@
+/*
+ * 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