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/* GStreamer
* Copyright (C) 2009 Tiago Katcipis <tiagokatcipis@gmail.com>
* Copyright (C) 2009 Paulo Pizarro <paulo.pizarro@gmail.com>
* Copyright (C) 2009 Rogério Santos <rogerio.santos@digitro.com.br>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <glib.h>
#include "vad_private.h"
#define VAD_POWER_ALPHA 0x0800 /* Q16 */
#define VAD_POWER_THRESHOLD 0x000010C7 /* -60 dB (square wave) */
#define VAD_ZCR_THRESHOLD 0
#define VAD_BUFFER_SIZE 256
union pgen
{
guint64 a;
gpointer v;
guint64 *l;
guchar *b;
guint16 *w;
gint16 *s;
};
struct _cqueue_s
{
union pgen base;
union pgen tail;
union pgen head;
gint size;
};
typedef struct _cqueue_s cqueue_t;
struct _vad_s
{
gint16 vad_buffer[VAD_BUFFER_SIZE];
cqueue_t cqueue;
gint vad_state;
guint64 hysteresis;
guint64 vad_samples;
guint64 vad_power;
long vad_zcr;
};
VADFilter *
vad_new (guint64 hysteresis)
{
VADFilter *vad = malloc (sizeof (VADFilter));
vad_reset (vad);
vad->hysteresis = hysteresis;
return vad;
}
void
vad_reset (VADFilter * vad)
{
memset (vad, 0, sizeof (*vad));
vad->cqueue.base.s = vad->vad_buffer;
vad->cqueue.tail.a = vad->cqueue.head.a = 0;
vad->cqueue.size = VAD_BUFFER_SIZE;
vad->vad_state = VAD_SILENCE;
}
void
vad_destroy (VADFilter * p)
{
free (p);
}
void
vad_set_hysteresis (struct _vad_s *p, guint64 hysteresis)
{
p->hysteresis = hysteresis;
}
guint64
vad_get_hysteresis (struct _vad_s *p)
{
return p->hysteresis;
}
gint
vad_update (struct _vad_s * p, gint16 * data, gint len)
{
guint64 tail;
gint frame_type;
gint16 sample;
gint i;
for (i = 0; i < len; i++) {
p->vad_power = VAD_POWER_ALPHA * ((data[i] * data[i] >> 14) & 0xFFFF) +
(0xFFFF - VAD_POWER_ALPHA) * (p->vad_power >> 16) +
((0xFFFF - VAD_POWER_ALPHA) * (p->vad_power & 0xFFFF) >> 16);
/* Update VAD buffer */
p->cqueue.base.s[p->cqueue.head.a] = data[i];
p->cqueue.head.a = (p->cqueue.head.a + 1) & (p->cqueue.size - 1);
if (p->cqueue.head.a == p->cqueue.tail.a)
p->cqueue.tail.a = (p->cqueue.tail.a + 1) & (p->cqueue.size - 1);
}
tail = p->cqueue.tail.a;
p->vad_zcr = 0;
for (;;) {
sample = p->cqueue.base.s[tail];
tail = (tail + 1) & (p->cqueue.size - 1);
if (tail == p->cqueue.head.a)
break;
p->vad_zcr +=
((sample & 0x8000) != (p->cqueue.base.s[tail] & 0x8000)) ? 1 : -1;
}
frame_type = (p->vad_power > VAD_POWER_THRESHOLD
&& p->vad_zcr < VAD_ZCR_THRESHOLD) ? VAD_VOICE : VAD_SILENCE;
if (p->vad_state != frame_type) {
/* Voice to silence transition */
if (p->vad_state == VAD_VOICE) {
p->vad_samples += len;
if (p->vad_samples >= p->hysteresis) {
p->vad_state = frame_type;
p->vad_samples = 0;
}
} else {
p->vad_state = frame_type;
p->vad_samples = 0;
}
} else {
p->vad_samples = 0;
}
return p->vad_state;
}
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