ref: 631a9484ffda7cc636b4096041bd0bc4005cb929
dir: /src/silence.c/
/*
* silence - effect to detect periods of silence in audio data and
* use this to clip data before and after.
*
* Written by Chris Bagwell (cbagwell@sprynet.com) - January 10, 1999
*
* Copyright 1999 Chris Bagwell And Sundry Contributors
* This source code is freely redistributable and may be used for
* any purpose. This copyright notice must be maintained.
* Chris Bagwell And Sundry Contributors are not responsible for
* the consequences of using this software.
*/
#include "st.h"
/* Private data for SKEL file */
typedef struct silencestuff {
int threshold;
int threshold_length;
int threshold_count;
int begin;
int begin_skip;
int begin_count;
int end;
int end_skip;
int end_count;
} *silenc_t;
/*
* Process options
*
* Don't do initialization now.
* The 'info' fields are not yet filled in.
*/
int st_silence_getopts(effp, n, argv)
eff_t effp;
int n;
char **argv;
{
if (n)
{
st_fail("Silence effect takes no options.");
return (ST_EOF);
}
}
/*
* Prepare processing.
* Do all initializations.
*/
int st_silence_start(effp)
eff_t effp;
{
silence_t silence = (silence_t) effp->priv;
silence.threshold = 5;
silence.thres_length = 1000;
silence.thres_count = 0;
silence.begin = silence.end = 0;
silence.begin_skip = silence.end_skip = 0;
silence.begin_count = silence.end_count = 0;
return (ST_SUCCESS);
}
/*
* Processed signed long samples from ibuf to obuf.
* Return number of samples processed.
*/
int st_silence_flow(effp, ibuf, obuf, isamp, osamp)
eff_t effp;
LONG *ibuf, *obuf;
LONG *isamp, *osamp;
{
silence_t silence = (silence_t) effp->priv;
int len, done;
len = ((*isamp > *osamp) ? *osamp : *isamp);
for(done = 0; done < len; done++) {
if (silence.threshold_count >= silence.threshold_length) {
if no more samples
break
get a sample
l = sample converted to signed long
*buf++ = l;
}
*isamp =
*osamp =
return (ST_SUCCESS);
}
/*
* Drain out remaining samples if the effect generates any.
*/
int st_skel_drain(effp, obuf, osamp)
LONG *obuf;
LONG *osamp;
{
*osamp = 0;
return (ST_SUCCESS);
}
/*
* Do anything required when you stop reading samples.
* (free allocated memory, etc.)
*/
int st_skel_stop(effp)
eff_t effp;
{
/* nothing to do */
return (ST_SUCCESS);
}