psearch.h

g729 coding ipaddressing

/**************************************************************************
*
* ROUTINE
*				psearch
*
* FUNCTION
*				find pitch VQ parameters
*
* SYNOPSIS
*				subroutine psearch(l)
*
*	formal 
*
*						data	I/O
*		name			type	type	function
*		-------------------------------------------------------------------
*		l				int 	i		dimension of s
*
*	external 
*						data	I/O
*		name			type	type	function
*		-------------------------------------------------------------------
*		idb 			int 	i		dimension of d1a and d1b???
*		no				int 	i		filter order  predictor
*		nseg			int 	i		segment counter
*		pindex			int 	i/o 	pitch gain index bb[2]
*		bb				float	i/o 	pitch predictor coefficients
*		d1b[]			float	i/o 	memory 1/P(z)
*		frame			int 	i
*		h[] 			float	i/o 	impulse response
*		ptype[] 		char	i		pitch gain (bb[2]) quantizer type
*		pstype[]		char	i		pitch search type
*		pitch_gain_vid	int 	i
*		pitch_qgain_vid int 	i
*		pitch_match_vid int 	i
*		pitch_ir_vid	int 	i
*		fndpp_v0_vid	int 	i
*		tauptr			int 			pitch delay pointer
*		pdelay			float			pitch delay coding table
*		minptr			int 			minimum delay pointer
*		plevel1 		int 			number of full search pitch delays
*		plevel2 		int 			number of delta search pitch delays
*
***************************************************************************
*		
* DESCRIPTION
*
*  Pitch search is performed by closed-loop analysis using a modification
*  of what is commonly called any one of the following: "self-excited",
*  "adaptive code book" or "VQ" method.  This method was found to be
*  superior to the conventional "filtering approach", especially for high
*  pitched speakers.  The filtering and VQ methods are identical except when
*  the delay is less than the frame length.  The pitch delay ranges from minptr
*  to maxptr (i.e., 20 to 147 including noninteger) lags every odd subframe 
*  while even subframes are searched and coded within 2**pbits[1] (i.e., 32)  
*  lags relative to the previous subframe.	The delta search greatly reduces
*  the computational complexity and data rate while causing no percievable 
*  loss in speech quality.
*
*  The minimum squared prediction error (MSPE) search criteria is modified
*  to check the error at submultiples of the delay to determine if it is
*  within 1 dB of the MSPE.  The submultiple delay is selected if its error
*  satisfies our modified criteria.  This results in a smooth "pitch" delay
*  contour which produces higher quality speech and is crucial to the
*  synthesizer's smoother in the presence of bit errors. 
*		
***************************************************************************
*
* CALLED BY
*
*		csub
*
* CALLS
*
*		 movefr   pitchencode	pgain	save_sg   delay
*
**************************************************************************
*
* REFRENCES
*
*		Tremain, Thomas E., Joseph P. Campbell, Jr and Vanoy C. Welch,
*       "A 4.8 kbps Code Excited Linear Predictive Coder," Proceedings
*		of the Mobile Satellite Conference, 3-5 May 1988, pp. 491-496.
*
*		Campbell, Joseph P. Jr., Vanoy C. Welch and Thomas E. Tremain,
*       "An Expandable Error-Protected 4800 bps CELP Coder (U.S. Federal
*       Standard 4800 bps Voice Coder)," Proceedings of ICASSP, 1989.
*		(and Proceedings of Speech Tech, 1989.)
*
*       Kroon, Peter and Bishnu Atal, "On Improving the Performance of
*       Pitch Predictions in Speech Coding Systems," IEEE Speech Coding
*		Workshop, September 1989.
*
*       Marques, J.S., et al., "Pitch Prediction with Fractional Delays
*       in CELP Coding," European Conference on Speech Communication and
*		Technology, September, 1989.
*
**************************************************************************/
#define LEN 			30	/* *length of truncated impulse response	 */

#define MAXBUFPTR		MMAX + MAXNO + 2  * MAXLP + MAXNP - 1

static const int submult[MAXPD][4] = 
{
#include "submult.h"      /* *load pitch submultiple delay table         */
};

#ifdef CELP_USE_CONTEXT
#define d1b		(ctx->CSUB_d1b)
#endif

static void psearch(int l)
{
  int i, m, lag, start;
  int first, bigptr, subptr, topptr, maxptr, bufptr;
#ifdef CELP_USE_CONTEXT
#define oldptr	(ctx->PSEARCH_oldptr)
#else
  static int oldptr = {1};
#endif
  float g[MAXPD], match[MAXPD], emax;
  int fraction, neigh, whole, sub, nrange = 0;


  /*    See warning below ----------------  \/ max (MAXL, MAXLP)        */

  float v0[MAXBUFPTR], v0shift[MAXLP], frac;

/*																		 */
/* *choose type of pitch delay search:									 */
/*		*two stage hierarchical search of integer and neighboring		 */
/*		*noninteger delays												 */

  if (strcmp(pstype, "hier") == 0) 
  {
	whole = 1;
	fraction = 0;
	sub = 1;
	neigh = 1;
	nrange = 3;
  }

  /*	*integer only search											 */

  else if (strcmp(pstype, "intg") == 0)
  {
	whole = 1;
	fraction = 0;
	sub = 1;
	neigh = 0;
  }

  /*	*full exhaustive search 										 */

  else if (strcmp(pstype, "full") == 0)
  {
	whole = 1;
	fraction = 1;
	sub = 1;
	neigh = 0;
  }
  else
  {
#ifdef CELPDIAG
    fprintf(stderr, "psearch: incorrect pitch search type (pstype)");
#endif
	CELP_ERROR(CELP_ERR_PITCH_TYPE);
	return;
  }

  /* *initialize arrays 												 */

  for (i = 0; i < MAXBUFPTR; i++)
	v0[i] = 0.0;

   for (i = 0; i < MAXLP; i++)
	v0shift[i] = 0.0;

  for (i = 0; i < MAXPD; i++)
	g[i] = match[i] = 0.0;

  if (LEN > l) 
  {
#ifdef CELPDIAG
    fprintf(stderr,"psearch: impulse resp too long\n");
#endif
	CELP_ERROR(CELP_ERR_IMPULSE_LENGTH);
	return;
  }    
  bufptr = MMAX + no + 2*l + MAXNP - 1;
  if (MAXLP < MAXL)
  {
#ifdef CELPDIAG
    fprintf(stderr,"psearch: MAXLP < MAXL\n");
#endif
	CELP_ERROR(CELP_ERR_MAXLP);
	return;
  }

  /* *update adaptive code book (pitch memory)							 */

  movefr(idb, d1b, &v0[bufptr - idb - l]);

  /* *initial conditions												 */

  if (nseg == 1)
  {
	bb[2] = 0.0;
	bb[0] = MMIN;
  }
  else
  {

	/*			*find allowable pointer range (minptr to maxptr)		 */
				
	if ((nseg % 2) == 0)
	{

	/* *delta delay coding on even subframes							 */

	  minptr = oldptr - (plevel2/2 - 1);
	  maxptr = oldptr + (plevel2/2);
	  if (minptr < 0)
	  {
		minptr = 0;
		maxptr = plevel2 - 1;
	  }
	  if (maxptr > plevel1 - 1)
	  {
		  maxptr = plevel1 - 1;
		  minptr = plevel1 - plevel2;
	  }
	}
	else
	{

	/* *full range coding on odd subframes								 */

	  minptr = 0;
	  maxptr = plevel1 - 1;
	}

	start = bufptr - l + 1;


	/* *find gain and match score for integer pitch delays				 */
	/* *(using end-point correction on unity spaced delays) 			 */

	if (whole)
	{
	  first = TRUE;
	  for (i = minptr; i <= maxptr; i++)
	  {
		m = (int) pdelay[i];
		frac = pdelay[i] - m;
		if (fabs(frac) < 1.e-4)
		{
		  lag = start - m;
		  g[i] = pgain(&v0[lag-1], l, first, m, LEN, &match[i]);
		  first = FALSE;
		}
		else
		  match[i] = 0.0;
	  }
	 }
  
	/* *find gain and match score for fractional delays 				 */
	/* *(beware of combining this loop with above loop!)				 */
	/* *(could use end-point correction on unity spaced delays) 		 */

	if (fraction)
	{
	  for (i = minptr; i <= maxptr; i++)
	  {
		m = (int) pdelay[i];
		frac = pdelay[i] - m;
		if (fabs(frac) >= 1.e-4)
		{
		  delay(v0, start, l, frac, m, v0shift);
		  g[i] = pgain(v0shift, l, TRUE, 70, LEN, &match[i]);
		}
	  }
	}

	/* *find pointer to top (MSPE) match score (topptr) 				 */
	/* *search for best match score (max -error term)					 */

	topptr = minptr;
	emax = match[topptr];
	for (i = minptr; i <= maxptr; i++)
	{
	  if (match[i] > emax)
	  {
		topptr = i;
		emax = match[topptr];
	  }
	}

	/* *for full search (odd) subframes:								 */
	/* *select shortest delay of 2, 3, or 4 submultiples. if its match	 */
    /* *is within 1 dB of MSPE to favor smooth "pitch"                   */

	tauptr = topptr;
	if (sub)
	{
	  if ((nseg % 2) != 0)
	  {

	  /* *for each submultiple {2, 3 & 4}								 */
  
		for (i = 1; i <= submult[topptr][0]; i++)
		{

		  /* *find best neighborhood match for given submultiple		 */

		  bigptr = submult[topptr][i];
		  for (subptr = mmax(submult[topptr][i] - 8, minptr); subptr <= 
			   mmin(submult[topptr][i] + 8, maxptr); subptr++)
		  {
			if (match[subptr] > match[bigptr])
			  bigptr = subptr;
		  }

		  /* *select submultiple match if within 1 dB MSPE match		 */

		  if (match[bigptr] >= 0.88 * match[topptr])
		  {
			tauptr = bigptr;
		  }
		}
	  }
	}

    /* *search tauptr's neighboring delays                               */
	/* *(to be used with earlier stages of searching)					 */
	/* *find gain and match score for neighboring delays				 */
	/* *and find best neighborhood match								 */
	/* *(could use end-point correction on unity spaced delays) 		 */

	if (neigh)
	{
	  bigptr = tauptr;
	  for (i = mmax(tauptr - nrange, minptr); i <= mmin(tauptr + nrange, maxptr); i++)
	  {
		if (i != tauptr)
		{
		  m = (int) pdelay[i];
		  frac = pdelay[i] - m;
		  lag = start - m;
		  if (fabs(frac) < 1.e-4)
			g[i] = pgain(&v0[lag - 1], l, TRUE, m, LEN, &match[i]);
		  else
		  {
			delay(v0, start, l, frac, m, v0shift);
			g[i] = pgain(v0shift, l, TRUE, 70, LEN, &match[i]);
		  }
		  if (match[i] > match[tauptr])
			bigptr = i;
		}
	  }
	  tauptr = bigptr;
	}

	/* *OPTIONAL (may be useful for integer DSPs)						 */
	/* *given chosen pointer to delay (tauptr), recompute its			 */
	/* *gain to correct errors accumulated in recursions				 */
	/* *and errors due to truncation									 */

	m = (int) pdelay[tauptr];
	frac = pdelay[tauptr] - m;
	lag = start - m;
	if (fabs(frac) < 1.e-4)

	/* *integer delay:													 */

	  g[tauptr] = pgain(&v0[lag - 1], l, TRUE, m, l, &match[tauptr]);
	else

	/* *fractional delay:												 */

	{
	  delay(v0, start, l, frac, m, v0shift);
	  g[tauptr] = pgain(v0shift, l, TRUE, 70, l, &match[tauptr]);
	}

    /* *place pitch parameters in common bb "structure"                  */

	bb[2] = g[tauptr];
	bb[0] = pdelay[tauptr];

	/* *save pitch pointer to determine delta delay 					 */

	oldptr = tauptr;
  }

  /* *pitch quantization bb[2]											 */

  if (strncmp(ptype, "none", 4) != 0)
	bb[2] = pitchencode(bb[2], &pindex);
  else {
#ifdef CELPDIAG
    fprintf(stderr, "psearch: no pitch quantization!\n");
#endif
  }
}

#undef LEN
#undef MAXBUFPTR

#ifdef CELP_USE_CONTEXT
#undef d1b
#undef oldptr
#endif