intanaly.c

语音CELP压缩解压源代码（C语音)

/**************************************************************************
*
* ROUTINE
*		intanaly
*
* FUNCTION
*		Linearly interpolate between transmitted LSPs
*		to generate nn (=4) intermediate sets of LSP
*		frequencies for subframe analysis. 
*		
*
* SYNOPSIS
*		subroutine intanaly(lspnew, nn, lsp)
*
*   formal 
*
*                       data    I/O
*       name            type    type    function
*       -------------------------------------------------------------------
*	lspnew		float	i	new frequency array
*	nn		int	i	number of segments/frame
*	lsp		float	o	interpolated frequency matrix
*
*   external 
*                       data    I/O
*       name            type    type    function
*       -------------------------------------------------------------------
*	no		int	i
*	frame		int	i
*
***************************************************************************
*
* DESCRIPTION
*		This routine linearly interpolates lsp's for analysis in
*	nn (=4) subframes.  This is a combination of inter- and 
*	intra-frame interpolation.  There are two routines, one for the 
*	analyzer and one for the synthesizer.
*
*		The lsps are interpolated from two transmitted frames,
*	 old and new.  The lsp interpolation is calculated as follows:
*
*	superframe:       old	    	       new
*
*		|	      	      |      		    |
*		|---------------------|---------------------|
*		|	      	      |      		    |
*
*	         \		                           /
*                 \                                       /
*
*	subframe:         1       2        3        4
*		     |			       	         |
*	       ...---|--------|--------|--------|--------|
*		     |			                 |
*			  v       v        v        v
*
*	weighting:
*		old:     7/8      5/8      3/8      1/8
*		new:     1/8      3/8      5/8      7/8
*
*	Note: This is dependent on nn = ll/l = 4!
*	
***************************************************************************
*
* CALLED BY
*
*	celp
*
* CALLS
*
*
*
**************************************************************************/
#define TRUE	1
#define FALSE	0
#include "ccsub.h"
extern int no, frame;
static float tempfreq, w[2][4] =   { 0.875, 0.625, 0.375, 0.125,  
                                     0.125, 0.375, 0.625, 0.875};
intanaly(lspnew, nn, lsp)
int nn;
float lspnew[], lsp[][MAXNO];
{
  int i, j, nonmono;
  static float lspold[MAXNO] = {.03, .05, .09, .13, .19,                                           .23, .29, .33, .39, .44};
  static float oldlsp[MAXNO];

  for (i = 0; i < nn; i++)

  /* *interpolate lsp's						 */

  {
    for (j = 0; j < no; j++)
      lsp[i][j] = w[0][i]*lspold[j] + w[1][i]*lspnew[j];

    /* *OPTIONAL bug checker
       *check for monotonically increasing lsp's
       *swap crossed LSPs					*/
  
    for (j = 1; j < no; j++)
    {
      if (lsp[i][j] < lsp[i][j - 1])
      {
        printf("intanaly: Swapping nonmono lsps @ frame %d\n", frame);
        tempfreq = lsp[i][j];
        lsp[i][j] = lsp[i][j - 1];
        lsp[i][j - 1] = tempfreq;
      }
    }

    /* *recheck for monotonically increasing lsp's
       *substitute old LSPs (they must be really messed up!)	*/
  
    nonmono = FALSE;
    for (j = 1; j < no; j++)
    {
      if (lsp[i][j] < lsp[i][j - 1]) 
        nonmono = TRUE;
    }
    if (nonmono)
    {
      printf("intanaly: Resetting interp LSP at frame %d\n", frame);
      for (j = 0; j < no; j++)
      {
        if (i == 0)
          lsp[i][j] = oldlsp[j];
        else
          lsp[i][j] = lsp[i - 1][j];
      }
    }
  }
  
  /*		*save lsp's for next pass				*/
  
  for (j = 0; j < no; j++)
  {
    lspold[j] = lspnew[j];
    oldlsp[j] = lsp[nn][j];
  }
}