/* ==================================================================== * Copyright (c) 1999-2001 Carnegie Mellon University. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * ==================================================================== * */ /* * cont_ad.h -- Continuous A/D listening and silence filtering module. * * ********************************************** * CMU ARPA Speech Project * * Copyright (c) 1996 Carnegie Mellon University. * ALL RIGHTS RESERVED. * ********************************************** * * HISTORY * * 13-Jul-98 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Added spf and adbufsize to cont_ad_t in order to support variable * frame sizes depending on audio sampling rate. * * 30-Jun-98 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Added FILE* argument to cont_ad_powhist_dump(). * * 16-Jan-98 Paul Placeway (pwp@cs.cmu.edu) at Carnegie Mellon University * Changed to use dB instead of the weird power measure. * Added most system parameters to cont_ad_t instead of hardwiring * them in cont_ad.c. * Added cont_ad_set_params() and cont_ad_get_params(). * * 28-Jul-96 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Added cont_ad_t.siglvl. * * 27-Jun-96 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Added the option for cont_ad_read to return -1 on EOF. * * 21-Jun-96 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Added cont_ad_set_thresh(). * * 20-Jun-96 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Separated thresholds for speech and silence. * * 17-Jun-96 M K Ravishankar (rkm@cs.cmu.edu) at Carnegie Mellon University * Created, based loosely on Steve Reed's original implementation. */ #ifndef _CONT_AD_H_ #define _CONT_AD_H_ /* * This module is intended to be interposed as a filter between any raw A/D source and the * application to remove silence regions. Its main purpose is to remove regions of * silence from the raw input speech. It is initialized with a raw A/D source function * (during the cont_ad_init call). The application is responsible for setting up the A/D * source, turning recording on and off as it desires. Filtered A/D data can be read by * the application using the cont_ad_read function. * * In other words, the application calls cont_ad_read instead of the raw A/D source function * (e.g., ad_read in libad) to obtain filtered A/D data with silence regions removed. This * module itself does not enforce any other structural changes to the application. * * The cont_ad_read function also updates an "absolute" timestamp (see cont_ad_t.read_ts) at * the end of each invocation. The timestamp indicates the total #samples of A/D data read * until this point, including data discarded as silence frames. The application is * responsible for using this timestamp to make any policy decisions regarding utterance * boundaries or whatever. */ #include /* * Data structure for maintaining speech (non-silence) segments not yet consumed by the * application. FOR THE INTERNAL USE OF THIS MODULE. */ typedef struct spseg_s { int32 startfrm; /* Frame-id in adbuf (see below) of start of this segment */ int32 nfrm; /* #frames in segment (may wrap around adbuf) */ struct spseg_s *next; /* Next speech segment (with some intervening silence) */ } spseg_t; /* * Continuous listening module or object. An application can open and maintain several * such objects, if necessary. * FYI: Module always in one of two states: SILENCE or SPEECH. Transitions between the * two detected by sliding a window spanning several frames and looking for some minimum * number of frames of the other type. */ typedef struct { /* Function to be called for obtaining A/D data (see prototype for ad_read in ad.h) */ int32 (*adfunc)(ad_rec_t *ad, int16 *buf, int32 max); ad_rec_t *ad; /* A/D device argument for adfunc. Also, ad->sps used to determine frame size (spf, see below) */ int16 *adbuf; /* Circular buffer for maintaining A/D data read until consumed */ int32 read_ts; /* Timestamp (total no. of raw A/D samples read, silence+speech) at the end of the most recent cont_ad_read call */ int32 siglvl; /* Max signal level for most recently read data (0-16; #bits) */ int32 sps; /* Samples/sec; moved from ad->sps to break dependence on ad by N. Roy.*/ int32 spf; /* Samples/frame; audio level is analyzed within frames */ int32 adbufsize; /* Buffer size (#samples) */ int32 prev_sample; /* For pre-emphasis filter */ int32 headfrm; /* Frame # in adbuf with unconsumed A/D data */ int32 n_frm; /* #Complete frames of unconsumed A/D data in adbuf */ int32 n_sample; /* #Samples of unconsumed data in adbuf */ int32 tot_frm; /* Total #frames of A/D data read, including consumed ones */ int32 noise_level; /* PWP: what we claim as the "current" noise level */ int32 *pow_hist; /* Histogram of frame power, moving window, decayed */ char *frm_pow; /* Frame power */ int32 auto_thresh; /* Do automatic threshold adjustment or not */ int32 delta_sil; /* Max silence power/frame ABOVE noise level */ int32 delta_speech; /* Min speech power/frame ABOVE noise level */ int32 min_noise; /* noise lower than this we ignore */ int32 max_noise; /* noise higher than this signals an error */ int32 winsize; /* how many frames to look at for speech det */ int32 speech_onset; /* start speech on >= these many frames out of winsize, of >= delta_speech */ int32 sil_onset; /* end speech on >= these many frames out of winsize, of <= delta_sil */ int32 leader; /* pad beggining of speech with this many extra frms */ int32 trailer; /* pad end of speech with this many extra frms */ int32 thresh_speech;/* Frame considered to be speech if power >= thresh_speech (for transitioning from SILENCE to SPEECH state) */ int32 thresh_sil; /* Frame considered to be silence if power <= thresh_sil (for transitioning from SPEECH to SILENCE state) */ int32 thresh_update;/* #Frames before next update to pow_hist/thresholds */ int32 state; /* Current state, SILENCE or SPEECH */ int32 win_startfrm; /* Where next analysis window begins */ int32 win_validfrm; /* #Frames currently available from win_startfrm for analysis */ int32 n_other; /* If in SILENCE state, #frames in analysis window considered to be speech; otherwise #frames considered to be silence */ int32 n_in_a_row; /* number of frames sequentially other side of thresh */ spseg_t *spseg_head;/* First of unconsumed speech segments */ spseg_t *spseg_tail;/* Last of unconsumed speech segments */ } cont_ad_t; /* * One time initialization of a continuous listening/silence filtering object/module. * Return value: pointer to a READ-ONLY structure used in other calls to the object. * If any error occurs, the return value is NULL. */ cont_ad_t *cont_ad_init (ad_rec_t *ad, /* In: The A/D source object to be filtered */ int32 (*adfunc)(ad_rec_t *ad, int16 *buf, int32 max)); /* In: adfunc = source function to be invoked to obtain raw A/D data. See ad.h for the required prototype definition. */ /* * Calibration to determine an initial silence threshold. This function can be called * any number of times. It should be called at least once immediately after cont_ad_init. * The silence threshold is also updated internally once in a while, so this function * only needs to be called in the middle if there is a definite change in the recording * environment. * The application is responsible for making sure that the raw audio source is turned on * before the calibration. * Return value: 0 if successful, <0 otherwise. */ int32 cont_ad_calib (cont_ad_t *cont); /* In: object pointer returned by cont_ad_init */ /* * If the application has not passed an audio device into the silence filter * at initialisation, this routine can be used to calibrate the filter. The * buf (of length max samples) should contain audio data for calibration. This * data is assumed to be completely consumed. More than one call may be * necessary to fully calibrate. * Return value: 0 if successful, <0 on failure, >0 if calibration not * complete. */ int32 cont_ad_calib_loop (cont_ad_t *r, int16 *buf, int32 max); /* * Read A/D data pre-filtered to remove silence segments. * Return value: #samples actually read, possibly 0; <0 if EOF on A/D source. * The function also updates r->read_ts and r->siglvl (see above). */ int32 cont_ad_read (cont_ad_t *r, /* In: Object pointer returned by cont_ad_init */ int16 *buf, /* Out: On return, buf contains A/D data returned by this function, if any. NOTE: buf must be at least 256 samples long */ int32 max); /* In: Max #samples to be filled into buf */ /* * Set silence and speech threshold parameters. The silence threshold is the max power * level, RELATIVE to the peak background noise level, in any silence frame. Similarly, * the speech threshold is the min power level, RELATIVE to the peak background noise * level, in any speech frame. In general, silence threshold <= speech threshold. * Increasing the thresholds (say, from the default value of 2 to 3 or 4) reduces the * sensitivity to background noise, but may also increase the chances of clipping actual * speech. * Return value: 0 if successful, <0 otherwise. */ int32 cont_ad_set_thresh (cont_ad_t *cont, /* In: Object ptr from cont_ad_init */ int32 sil, /* In: silence threshold (default 2) */ int32 sp); /* In: speech threshold (default 2) */ /* * PWP 1/14/98 -- set the changable params. * * delta_sil, delta_speech, min_noise, and max_noise are in dB, * winsize, speech_onset, sil_onset, leader and trailer are in frames of * 16 ms length (256 samples @ 16kHz sampling). */ int32 cont_ad_set_params (cont_ad_t *r, int32 delta_sil, int32 delta_speech, int32 min_noise, int32 max_noise, int32 winsize, int32 speech_onset, int32 sil_onset, int32 leader, int32 trailer); /* * PWP 1/14/98 -- get the changable params. * * delta_sil, delta_speech, min_noise, and max_noise are in dB, * winsize, speech_onset, sil_onset, leader and trailer are in frames of * 16 ms length (256 samples @ 16kHz sampling). */ int32 cont_ad_get_params (cont_ad_t *r, int32 *delta_sil, int32 *delta_speech, int32 *min_noise, int32 *max_noise, int32 *winsize, int32 *speech_onset, int32 *sil_onset, int32 *leader, int32 *trailer); /* * Reset, discarding any accumulated speech segments. * Return value: 0 if successful, <0 otherwise. */ int32 cont_ad_reset (cont_ad_t *cont); /* In: Object pointer from cont_ad_init */ /* * Close the continuous listening object. */ int32 cont_ad_close (cont_ad_t *cont); /* In: Object pointer from cont_ad_init */ /* * Dump the power histogram. For debugging... */ void cont_ad_powhist_dump (FILE *fp, cont_ad_t *cont); /* * Detach the given continuous listening module from the associated audio device. * Return 0 if successful, -1 otherwise. */ int32 cont_ad_detach (cont_ad_t *c); /* * Attach the continuous listening module to the given audio device/function. * (Like cont_ad_init, but without the calibration.) * Return 0 if successful, -1 otherwise. */ int32 cont_ad_attach (cont_ad_t *c, ad_rec_t *a, int32 (*func)(ad_rec_t *, int16 *, int32)); void cont_ad_set_logfp (FILE *fp); /* File containing detailed logs (if non-NULL) */ /* * Set the silence and speech thresholds. For this to have any effect, the * auto_thresh field of the continuous listening module should be set to * FALSE. */ int32 cont_set_thresh(cont_ad_t *r, int32 silence, int32 speech); #endif