cmn_prior.c

来自「CMU大名鼎鼎的SPHINX－3大词汇量连续语音识别系统」· C语言 代码 · 共 120 行

/* ====================================================================
 * Copyright (c) 1999-2004 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 work was supported in part by funding from the Defense Advanced 
 * Research Projects Agency and the National Science Foundation of the 
 * United States of America, and the CMU Sphinx Speech Consortium.
 *
 * 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, 
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 * 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.
 *
 * ====================================================================
 *
 */
/*************************************************
 * CMU ARPA Speech Project
 *
 * Copyright (c) 2000 Carnegie Mellon University.
 * ALL RIGHTS RESERVED.
 * **********************************************
 * 
 * 30-Dec-2000  Rita Singh ([e-mail]) at Carnegie Mellon University
 * Created
 */


#include "cmn_prior.h"

void cmn_prior(float32 **incep, int32 varnorm, int32 nfr, int32 ceplen, 
							   int32 endutt)
{
  static float32 *cur_mean = NULL; /* the mean subtracted from input frames */
  static float32 *sum = NULL;	     /* the sum over input frames */
  static int32   nframe;	     /* the total number of input frames */
  static int32   initialize=1;
  float32 sf;
  int32   i, j;

  assert(incep!=NULL);
  
  if (varnorm)
    E_FATAL("Variance normalization not implemented in live mode decode\n");
  
  if (initialize){
    cur_mean = (float32 *) ckd_calloc(ceplen, sizeof(float32));
    
    /* A front-end dependent magic number */
    cur_mean[0] = 12.0;
    
    sum      = (float32 *) ckd_calloc(ceplen, sizeof(float32));
    nframe   = 0;
    initialize = 0;
    E_INFO("mean[0]= %.2f, mean[1..%d]= 0.0\n", cur_mean[0], ceplen-1);
  }
  
  if (nfr <= 0)
    return;
  
  for (i = 0; i < nfr; i++){
    for (j = 0; j < ceplen; j++){
      sum[j] += incep[i][j];
      incep[i][j] -= cur_mean[j];
    }
    ++nframe;
  }
  
  /* Shift buffer down if we have more than CMN_WIN_HWM frames */
  if (nframe > CMN_WIN_HWM) {
    sf = (float32) (1.0/nframe);
    for (i = 0; i < ceplen; i++)
      cur_mean[i] = sum[i] * sf;
    
    /* Make the accumulation decay exponentially */
    if (nframe >= CMN_WIN_HWM) {
      sf = CMN_WIN * sf;
      for (i = 0; i < ceplen; i++)
	sum[i] *= sf;
      nframe = CMN_WIN;
    }
  }
  
  if (endutt) {
    /* Update mean buffer */
    
    sf = (float32) (1.0/nframe);
    for (i = 0; i < ceplen; i++)
      cur_mean[i] = sum[i] * sf;
    
    /* Make the accumulation decay exponentially */
    if (nframe > CMN_WIN_HWM) {
      sf = CMN_WIN * sf;
      for (i = 0; i < ceplen; i++)
	sum[i] *= sf;
      nframe = CMN_WIN;
    }
    
  }
}