silence_detect.h revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
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*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
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* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
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/*
* Copyright (c) 1990-2001 by Sun Microsystems, Inc.
* All rights reserved.
*/
#ifndef _MULTIMEDIA_SILENCE_DETECT_H
#define _MULTIMEDIA_SILENCE_DETECT_H
#pragma ident "%Z%%M% %I% %E% SMI"
#include <audio_types.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* %M%
*
* Description:
*
* This file contains definitions of the public structures
* used by the silence detection function, 'silence_detect()'.
* There are two structures, one for specifying the start and end
* points of an interval of silence, and a second for maintaining
* the state of the silence detection algorithm between calls to
* 'silence_detect()'.
*/
/* Error returns. */
#define SILENCE_ERR_BUFFER_TOO_SMALL -1
#define SILENCE_ERR_REALLOC_FAILED -2
/*
* The interval in milliseconds over which
* zerocrossings are considered.
*/
#define ZEROCROSS_RANGE 25
/*
* The number of blocks needed for threshold
* determination.
*/
#define DATA_POINTS 10
/*
* The END_POINTS structure holds the index of the first point in
* the silence interval and the first point beyond the end of the
* silence interval.
*/
typedef struct {
int ep_start; /* Index of first point in silence interval. */
int ep_end; /* Index of first point beyond silence interval. */
} END_POINTS;
/*
* The SIL_STATE structure preserves the the state of the silence detection
* algorithm between calls to 'silence_detect'. It is allocated by calling
* 'silence_init_state'; it is initialized by calling 'silence_init_state';
* and it is deallocated by using 'silence_destroy_state'.
*
* The struct should not be directly modified by user programs.
*/
typedef struct {
unsigned int sampling_rate; /* The sampling rate. */
/*
* Length in samples of the algorithms
* analysis block. It should be
* equivalent to 10 msec. of data.
* It is set by 'silence_init'.
*/
int block_size;
/*
* Pointer to leftover data from the
* previous call.
*/
short *leftover;
/* Consolidated buffer. */
short *sbuf;
/*
* Indicates the position of the end of
* the current analysis frame (plus 2)
* relative to the start of the current
* buffer.
*/
int m;
/*
* Keeps track of the number of blocks
* collected for noise floor statistical
* characterization.
*/
int thr_calc_data_pts;
/*
* Records the algorithm's current place
* in the finite state machine governing
* silence interval detection.
*/
int sil_state;
/*
* Records how many consecutive analysis
* blocks have been processed in the
* current detection state.
*/
int state_exit_ind[5];
/*
* Size in samples of the product of
* ZEROCROSS_RANGE * 10 ms of data.
*/
int zerocross_range;
/*
* Stores the indices of the
* first element of the last ZERO_CROSS_RANGE
* blocks in the which the zerocrossing rate
* threshold was exceeded.
*/
int zerocross_ind[ZEROCROSS_RANGE];
/*
* Zerocrossing data for threshold
* calculation.
*/
int zerocross[DATA_POINTS];
/*
* Average absolute value data for
* threshold calculation.
*/
int abs_val[DATA_POINTS];
/*
* Zerocrossing threshold determined by
* 'silence_thrcalc().
*/
int zerocross_thr;
/*
* Absolute value threshold determined by
* 'silence_thrcalc().
*/
int abs_val_thr[2];
/*
* The tenative duration of silence.
* Several decisions made by the algorithm
* are based on whether or not this quanti-
* ty is less than the minimum duration
* of silence.
*/
int tentative_sil_dur;
/* Minimum duration of silence in samples. */
int min_sil_dur;
/*
* Stores the index of the tentative end
* of the most recent interval of speech
* relative to the start of the input
* buffer.
*/
int end_of_speech;
/*
* Stores the index of the tentative end
* of the most recent interval of silence
* relative to the start of the input
* buffer.
*/
int end_of_sil;
/*
* Pointer to the highest index entry of
* 'zerocross_cnt' whose value is less than
* ZEROCROSS_RANGE. It signifies the
* number of blocks since the least
* recent instance when the zerocrossing
* threshold was exceeded during the last
* 250 milliseconds.
*/
int *least_recent;
/*
* Array of structures containing the
* endpoints of silence intervals.
*/
/*
* Number of entries in the array
* of END_POINTS structures.
*/
int end_points_size;
/*
* Index to simplify the synchronization of
* silence end point storage. Whenever the
* indeterminate region stems from silence,
* the region's start is moved back 10 msecs
* to include one block of known silence.
* This variable stores the index of the
* start of that block of silence relative
* to the start of the current input
* buffer.
*/
int next_silence_start;
/*
* default absolute value threshold, used
* when the first 100ms of speech is loud.
*/
double noise;
long min_abs; /* minimum of absolute magnitude */
long max_abs; /* maximum of absolute magnitude */
double thr_scale; /* ratio for adaptive threshold adjustment */
long block_limit_low; /* absolute silence level for block */
long block_limit_high; /* absolute voice level for block */
} SIL_STATE;
(short *, END_POINTS **, unsigned int *, int *, SIL_STATE*));
#ifdef __cplusplus
}
#endif
#endif /* !_MULTIMEDIA_SILENCE_DETECT_H */