pitchvq.h

g729 coding ipaddressing

/**************************************************************************
*
* ROUTINE
*				pitchvq
*
* FUNCTION
*				Pitch VQ (n-taps, where n = 0, ..., 3)
*               "self-excited" or "vq" or "adaptive code book"
*
* SYNOPSIS
*				subroutine pitchvq(rar, idim, buf, idimb, b, type)
*
*	formal
*
*						data	I/O
*		name			type	type	function
*		-------------------------------------------------------------------
*		rar 			float	i/o 	Data segement/Filtered data segment
*		idim			int 	i		Dimension of data segement RAR
*		buf 			float	i/o 	Data buffer, dim IDIMB
*		idimb			int 	i		Dimension of data buffer is
*												max(M) + IDIM+1
*		b[0]			float	i		Pitch delay (M)
*		b[1-3]			float	i		pitch predictor coefficients.
*										BETA1=B(2),BETA2=B(3), BETA3=B(4)
*										For a 1-tap predictor B(2)=B(4)=0.0
*       type            char    i       Type "long" calls ldelay.c, the 
*										delay routine using long interpola-
*                                       tion windows.  Type "short" calls
*										delay.c, the short delay routine.
*
***************************************************************************
*
* CALLED BY
*
*		celp   confg
*
* CALLS
*
*		delay
*
*
***************************************************************************
*
* USAGE
*
*	 Adaptive code book (pitch) synthesis routine:
*
*	 1) For lags < frame size:	gain-shape adaptive code book VQ
*
*    2) For lags => frame size this is equivalent to a pitch synthesis "filter"
*
*							   -[b(1)-1]		-b(1)		 -[b(1)+1]
*		H(z) =	1 /  1 + b(2) z 		+ b(3) z	 + b(4) z
*
*		NOTE: largest delay must not exceed the value IDIMB-IDIM
*
*
***************************************************************************
*
* REFERENCES
*
*		Singhal & Atal, Improving Performance of Multi-Pulse LPC Coders at
*		Low Bit Rates, ICASSP, 1984.
*
*		Rose & Barnwell.  The Self Excited Vocoder-An Alternate Approcch 
*		to Toll Quality at 4800 bps, ICASSP, 1986, pp. 453-456.
*
*		Kleijn, Krasinski and Ketchum, Improved Speech Quality and 
*		Efficient Vector Quantization in SELP, ICASSP, 1988.
*
**************************************************************************/

static void pitchvq(float rar[], int idim, float buf[],
	int idimb, float b[], char type[])
{
  int k, m, i, start;
  float buf2[MAXLP], frac;

  k = idimb - idim;
  start = k + 1;
  m = (int) b[0];
  frac = b[0] - m;

  /* *update memory 													 */

  for (i = 0; i < k; i++)
	buf[i] = buf[i + idim];

  /* *update memory with selected pitch memory from selected delay (m)	  */

  if (fabs(frac) < 1.e-4)
  {
	for (i = k; i < idimb; i++) 
	  buf[i] = buf[i - m];
  }

  /* *fractional update if fractional part isn't "zero"                  */

  if (fabs(frac) > 1.e-4)
  {
    if (strcmp(type,"long") == 0)
	  ldelay(buf, start, idim, frac, m, buf2);
	else
	  delay(buf, start, idim, frac, m, buf2);
	for (i = 0; i < idim; i++)	
	  buf[i + k] = buf2[i];
  }

  /* *return "rar" with scaled memory added to stochastic contribution   */
  
	for (i = 0; i < idim; i++)	
	  buf[i + k] = rar[i] += b[2] * buf[i + k]; 
						   
}