www.pudn.com > CryptoPhone-src-031122.zip > postfilt.c

/* Copyright 2001,2002,2003 NAH6 
 * All Rights Reserved 
 * 
 * Parts Copyright DoD, Parts Copyright Starium 
 * 
 */ 
          /*LINTLIBRARY*/ 
          /*PROTOLIB1*/ 
 
#include "main.h" 
#include "filter.h" 
#include  
#include "bwexp.h" 
#include "lsftopc.h" 
#include "movarray.h" 
#include "pctorc.h" 
#include "postfilt.h" 
 
#define TC	0.01 
 
FILTER	PostP, PostZ, PostZ2; 
 
/************************************************************************** 
*                                                                         * 
* ROUTINE 
*		PostFilter 
* 
* FUNCTION 
*		Filter input signal 
* SYNOPSIS 
*		PostFilter(speech_in, lsf, frame_num, speech_out) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	speech_in	float	 i	input speech 
*	lsf		float	 i	input line spectral frequencies 
*	frame_num	int	 i	frame number 
*	speech		float	 o	output speech 
* 
*************************************************************************** 
* 
* CALLED BY 
* 
*	Synthesis 
* 
* CALLS 
* 
*	BWExpand do_zfilt_dynamic do_pfilt_dynamic PCtoRC MoveArray 
* 
**************************************************************************/ 
void PostFilter( 
float	speech_in[], 
float	lsf[], 
int	frame_num, 
float	speech_out[]) 
{ 
int		n; 
static float 	powerin=0.0; 
static float	powerout=0.0; 
float 		ast[2]; 
float 		pcexp1[ORDER + 1], pcexp2[ORDER + 1], rcexp2[ORDER]; 
float		alpha = 0.8; 
float		beta = 0.5; 
float		pc[ORDER+1]; 
 
#ifdef POSTFIL2 
float 		scale; 
#else 
float 		newpowerin[MAX_CW_VEC_LEN + 1], newpowerout[MAX_CW_VEC_LEN + 1]; 
#endif 
 
/*  estimate input power */ 
 
#ifdef POSTFIL2 
	for (n = 0; n < SF_LEN; n++) 
	  powerin = powerin * (1.0 - TC) + TC * speech_in[n] * speech_in[n]; 
#else 
	newpowerin[0] = powerin; 
	for (n = 0; n < SF_LEN; n++) 
	  newpowerin[n + 1] = (1.0 - TC) * newpowerin[n] +  
		TC * speech_in[n] * speech_in[n]; 
	powerin = newpowerin[SF_LEN]; 
#endif 
 
/*  Convert input LSFs to PCs */ 
	LSFtoPC(lsf, pc, frame_num); 
 
/*  BW expansion */ 
	BWExpand(beta, pc, pcexp1); 
	BWExpand(alpha, pc, pcexp2); 
 
/*  pole-zero postfilter */ 
	MoveArray(SF_LEN, speech_in, speech_out); 
	do_zfilt_dynamic(&PostZ, pcexp1, speech_out); 
	do_pfilt_dynamic(&PostP, pcexp2, speech_out); 
 
/*  find spectral tilt (1st order fit) of postfilter 
      (denominator dominates the tilt)			*/ 
	PCtoRC(pcexp2, rcexp2); 
 
/*  tilt compensation by a scaled zero 
      (don't allow hF roll-off)				*/ 
	ast[0] = 1.0; 
	ast[1] = (rcexp2[0] > 0.) ? -0.5 * rcexp2[0] : 0; 
	do_zfilt_dynamic(&PostZ2, ast, speech_out); 
 
/*  estimate output power	*/ 
 
#ifdef POSTFIL2 
	for (n = 0; n < SF_LEN; n++) 
	  powerout = powerout * (1.0 - TC) + TC * speech_out[n] * speech_out[n]; 
 
/*  block wise automatic gain control	*/ 
 
	if (powerout > 0.0) 
	  for (scale = sqrt(powerin / powerout), n = 0; n < SF_LEN; n++) 
      	    speech_out[n] *= scale; 
#else 
	newpowerout[0] = powerout; 
	for (n = 0; n < SF_LEN; n++) 
	  newpowerout[n + 1] = (1.0 - TC) * newpowerout[n] +  
		TC * speech_out[n] * speech_out[n]; 
	powerout = newpowerout[SF_LEN]; 
 
/*  sample wise automatic gain control	*/ 
 
	for (n = 0; n < SF_LEN; n++) 
	{ 
	  if (newpowerout[n + 1] > 0.0) 
	    speech_out[n] *= (float)sqrt((double)(newpowerin[n + 1] / newpowerout[n + 1])); 
	} 
#endif 
 
 
}