--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/time_scale.c	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,242 @@
+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * time_scale.c - Time scaling for linear speech data
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2004 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * $Id: time_scale.c,v 1.15 2006/11/19 14:07:25 steveu Exp $
+ */
+
+/*! \file */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <inttypes.h>
+#include <string.h>
+#include <fcntl.h>
+#include <time.h>
+#include <limits.h>
+#if defined(HAVE_TGMATH_H)
+#include <tgmath.h>
+#endif
+#if defined(HAVE_MATH_H)
+#include <math.h>
+#endif
+
+#include "spandsp/telephony.h"
+#include "spandsp/time_scale.h"
+
+/*
+    Time scaling for speech, based on the Pointer Interval Controlled
+    OverLap and Add (PICOLA) method, developed by Morita Naotaka.
+ */
+
+static __inline__ int amdf_pitch(int min_pitch, int max_pitch, int16_t amp[], int len)
+{
+    int i;
+    int j;
+    int acc;
+    int min_acc;
+    int pitch;
+
+    pitch = min_pitch;
+    min_acc = INT_MAX;
+    for (i = max_pitch;  i <= min_pitch;  i++)
+    {
+        acc = 0;
+        for (j = 0;  j < len;  j++)
+            acc += abs(amp[i + j] - amp[j]);
+        if (acc < min_acc)
+        {
+            min_acc = acc;
+            pitch = i;
+        }
+    }
+    return pitch;
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ void overlap_add(int16_t amp1[], int16_t amp2[], int len)
+{
+    int i;
+    double weight;
+    double step;
+    
+    step = 1.0/len;
+    weight = 0.0;
+    for (i = 0;  i < len;  i++)
+    {
+        /* TODO: saturate */
+        amp2[i] = (int16_t) ((double) amp1[i]*(1.0 - weight) + (double) amp2[i]*weight);
+        weight += step;
+    }
+}
+/*- End of function --------------------------------------------------------*/
+
+int time_scale_rate(time_scale_t *s, float rate)
+{
+    if (rate <= 0.0)
+        return -1;
+    /*endif*/
+    if (rate >= 0.99  &&  rate <= 1.01)
+    {
+        /* Treat rate close to normal speed as exactly normal speed, and
+           avoid divide by zero, and other numerical problems. */
+        rate = 1.0;
+    }
+    else if (rate < 1.0)
+    {
+        s->rcomp = rate/(1.0 - rate);
+    }
+    else
+    {
+        s->rcomp = 1.0/(rate - 1.0);
+    }
+    /*endif*/
+    s->rate = rate;
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int time_scale_init(time_scale_t *s, float rate)
+{
+    if (time_scale_rate(s, rate))
+        return -1;
+    /*endif*/
+    s->rate_nudge = 0.0;
+    s->fill = 0;
+    s->lcp = 0;
+    return 0;
+}
+/*- End of function --------------------------------------------------------*/
+
+int time_scale(time_scale_t *s, int16_t out[], int16_t in[], int len)
+{
+    double lcpf;
+    int pitch;
+    int out_len;
+    int in_len;
+    int k;
+
+    out_len = 0;
+    in_len = 0;
+
+    /* Top up the buffer */
+    if (s->fill + len < TIME_SCALE_BUF_LEN)
+    {
+        /* Cannot continue without more samples */
+        memcpy(s->buf + s->fill, in, sizeof(int16_t)*len);
+        s->fill += len;
+        return out_len;
+    }
+    k = (TIME_SCALE_BUF_LEN - s->fill);
+    memcpy(s->buf + s->fill, in, sizeof(int16_t)*k);
+    in_len += k;
+    s->fill = TIME_SCALE_BUF_LEN;
+    while (s->fill == TIME_SCALE_BUF_LEN)
+    {
+        while (s->lcp >= TIME_SCALE_BUF_LEN)
+        {
+            memcpy(out + out_len, s->buf, sizeof(int16_t)*TIME_SCALE_BUF_LEN);
+            out_len += TIME_SCALE_BUF_LEN;
+            if (len - in_len < TIME_SCALE_BUF_LEN)
+            {
+                /* Cannot continue without more samples */
+                memcpy(s->buf, in + in_len, sizeof(int16_t)*(len - in_len));
+                s->fill = len - in_len;
+                s->lcp -= TIME_SCALE_BUF_LEN;
+                return out_len;
+            }
+            memcpy(s->buf, in + in_len, sizeof(int16_t)*TIME_SCALE_BUF_LEN);
+            in_len += TIME_SCALE_BUF_LEN;
+            s->lcp -= TIME_SCALE_BUF_LEN;
+        }
+        if (s->lcp > 0)
+        {
+            memcpy(out + out_len, s->buf, sizeof(int16_t)*s->lcp);
+            out_len += s->lcp;
+            memcpy(s->buf, s->buf + s->lcp, sizeof(int16_t)*(TIME_SCALE_BUF_LEN - s->lcp));
+            if (len - in_len < s->lcp)
+            {
+                /* Cannot continue without more samples */
+                memcpy(s->buf + (TIME_SCALE_BUF_LEN - s->lcp), in + in_len, sizeof(int16_t)*(len - in_len));
+                s->fill = TIME_SCALE_BUF_LEN - s->lcp + len - in_len;
+                s->lcp = 0;
+                return out_len;
+            }
+            memcpy(s->buf + (TIME_SCALE_BUF_LEN - s->lcp), in + in_len, sizeof(int16_t)*s->lcp);
+            in_len += s->lcp;
+            s->lcp = 0;
+        }
+        if (s->rate == 1.0)
+        {
+            s->lcp = 0x7FFFFFFF;
+        }
+        else
+        {
+            pitch = amdf_pitch(SAMPLE_RATE/TIME_SCALE_MIN_PITCH, SAMPLE_RATE/TIME_SCALE_MAX_PITCH, s->buf, SAMPLE_RATE/TIME_SCALE_MIN_PITCH);
+            lcpf = (double) pitch*s->rcomp;
+            /* Nudge around to compensate for fractional samples */
+            s->lcp = (int) lcpf;
+            /* Note that s->lcp and lcpf are not the same, as lcpf has a fractional part, and s->lcp doesn't */
+            s->rate_nudge += s->lcp - lcpf;
+            if (s->rate_nudge >= 0.5)
+            {
+                s->lcp--;
+                s->rate_nudge -= 1.0;
+            }
+            else if (s->rate_nudge <= -0.5)
+            {
+                s->lcp++;
+                s->rate_nudge += 1.0;
+            }
+            if (s->rate < 1.0)
+            {
+                /* Speed up - drop a chunk of data */
+                overlap_add(s->buf, s->buf + pitch, pitch);
+                memcpy(&s->buf[pitch], &s->buf[2*pitch], sizeof(int16_t)*(TIME_SCALE_BUF_LEN - 2*pitch));
+                if (len - in_len < pitch)
+                {
+                    /* Cannot continue without more samples */
+                    memcpy(s->buf + TIME_SCALE_BUF_LEN - pitch, in + in_len, sizeof(int16_t)*(len - in_len));
+                    s->fill += (len - in_len - pitch);
+                    return out_len;
+                }
+                memcpy(s->buf + TIME_SCALE_BUF_LEN - pitch, in + in_len, sizeof(int16_t)*pitch);
+                in_len += pitch;
+            }
+            else
+            {
+                /* Slow down - insert a chunk of data */
+                memcpy(out + out_len, s->buf, sizeof(int16_t)*pitch);
+                out_len += pitch;
+                overlap_add(s->buf + pitch, s->buf, pitch);
+            }
+        }
+    }
+    return out_len;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/