monopred.c

MPEG2/MPEG4编解码参考程序(实现了MPEG4的部分功能)

/************************* MPEG-2 NBC Audio Decoder **************************
 *                                                                           *
"This software module was originally developed by 
Bernd Edler and Hendrik Fuchs, University of Hannover in the course of 
development of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 
14496-1,2 and 3. This software module is an implementation of a part of one or more 
MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 
Audio standard. ISO/IEC  gives users of the MPEG-2 NBC/MPEG-4 Audio 
standards free license to this software module or modifications thereof for use in 
hardware or software products claiming conformance to the MPEG-2 NBC/MPEG-4
Audio  standards. Those intending to use this software module in hardware or 
software products are advised that this use may infringe existing patents. 
The original developer of this software module and his/her company, the subsequent 
editors and their companies, and ISO/IEC have no liability for use of this software 
module or modifications thereof in an implementation. Copyright is not released for 
non MPEG-2 NBC/MPEG-4 Audio conforming products.The original developer
retains full right to use the code for his/her  own purpose, assign or donate the 
code to a third party and to inhibit third party from using the code for non 
MPEG-2 NBC/MPEG-4 Audio conforming products. This copyright notice must
be included in all copies or derivative works." 
Copyright(c)1996.
 *                                                                           *
 ****************************************************************************/

/* Minor modifications by Pierre Lauber, Fraunhofer Institute Erlangen */

/***********************************************************************************
 * MONOPRED									   *
 *										   *
 *	Contains the core functions for an intra channel (or mono) predictor	   *
 *	using a backward adaptive lattice predictor.				   *
 *										   *
 *	init_pred_stat():	initialisation of all predictor parameters	   *
 *	monopred():		calculation of a predicted value from		   *
 *				preceeding (quantised) samples		 	   *
 *	predict():		carry out prediction for all spectral lines	   *
 *	predict_reset():	carry out cyclic predictor reset mechanism	   *
 *				(long blocks) resp. full reset (short blocks)	   *
 *										   *
 *	Internal Functions:							   *
 *	  reset_pred_state():	reset the predictor state variables		   *
 *										   *
 **********************************************************************************/

#include <math.h>
#include <stdio.h>

#include "block.h"               /* handler, defines, enums */
#include "buffersHandle.h"       /* handler, defines, enums */
#include "concealmentHandle.h"   /* handler, defines, enums */
#include "interface.h"           /* handler, defines, enums */
#include "mod_bufHandle.h"       /* handler, defines, enums */
#include "monopredHandle.h"      /* handler, defines, enums */
#include "resilienceHandle.h"    /* handler, defines, enums */
#include "reorderspecHandle.h"   /* handler, defines, enums */
#include "tf_mainHandle.h"       /* handler, defines, enums */

#include "all.h"                 /* structs */
#include "monopredStruct.h"      /* structs */
#include "nok_ltp_common.h"      /* structs */
#include "nok_prediction.h"      /* structs */
#include "tf_mainStruct.h"       /* structs */
#include "tns.h"                 /* structs */

#include "allVariables.h"        /* variables */

#include "port.h"
#include "common_m4a.h"

#define GRAD	PRED_ORDER
static	float	ALPHA;
static	float	A;
static	float	B;
static	float	mnt_table[128];
static	float	exp_table[256];
static  int     last_rstgrp_num = 0;

#ifdef	NOT_USED
static void
flt_trunc(float *pf)
{
    ulong tmp;
    float *pt = (float *)&tmp;
    *pt = *pf;
    tmp &= (ulong)0xffff0000;
    *pf = *pt;
}
#endif

/* this works for all float values, 
 * but does not conform to IEEE conventions of
 * round to nearest, even
 */

/* Schuyler's bug fix */
static void
flt_round(float *pf)
{
    int flg;
    ulong tmp;
    float *pt = (float *)&tmp;
    *pt = *pf;
    flg = tmp & (ulong)0x00008000;
    tmp &= (ulong)0xffff0000;
    *pf = *pt;
    /* round 1/2 lsb toward infinity */
    if (flg) {
        tmp &= (ulong)0xff800000;       /* extract exponent and sign */
        tmp |= (ulong)0x00010000;       /* insert 1 lsb */
        *pf += *pt;                     /* add 1 lsb and elided one */
        tmp &= (ulong)0xff800000;       /* extract exponent and sign */
        *pf -= *pt;                     /* subtract elided one */
    }
}


/* This only works for 1.0 < float < 2.0 - 2^-24 !
 * 
 * Comparison of the performance of the two rounding routines:
 *		old (above)	new (below)
 * Max error	0.00385171	0.00179992
 * RMS error	0.00194603	0.00109221
 */

/* New bug fixed version */
static void
inv_table_flt_round(float *ftmp)
{
  int exp;
  double mnt;
  float descale;

    mnt = frexp((double)*ftmp, &exp);
    descale = (float)ldexp(1.0, exp + 15);
    *ftmp += descale;
    *ftmp -= descale;
}

static void
make_inv_tables(void)
{
    int i;
    ulong tmp1, tmp;
    float *pf = (float *)&tmp;
    float ftmp;

    *pf = 1.0;
    tmp1 = tmp;				/* float 1.0 */
    for (i=0; i<128; i++) {
	tmp = tmp1 + (i<<16);		/* float 1.m, 7 msb only */
    	ftmp = B / *pf;
    	inv_table_flt_round(&ftmp);	/* round to 16 bits */
	mnt_table[i] = ftmp;
	/* printf("%3d %08x %f\n", i, tmp, ftmp); */
    }
    for (i=0; i<256; i++) {
	tmp = (i<<23);			/* float 1.0 * 2^exp */
       	if (*pf > MINVAR) {
    	    ftmp = 1.0 / *pf;
            }
	else {
	    ftmp = 0;
        }
	exp_table[i] = ftmp;
	/* printf("%3d %08x %g\n", i, tmp, ftmp); */
    }
}

/* Bug-fixed version (big-little endian problem) */
void
inv_quant_pred_state(TMP_PRED_STATUS *tmp_psp, PRED_STATUS *psp)
{
    int i;
    short *p2;
    ulong *p1_tmp;


    p1_tmp = (ulong *)tmp_psp;
    p2 = (short *) psp;
    
    for (i=0; i<MAX_PRED_BINS*6; i++)
	    p1_tmp[i] = ((ulong)p2[i])<<16;

}

static void InverseQuantisationPredictorState(TMP_PRED_STATUS *tmp_psp, PRED_STATUS *psp)
{
  int i;
  short *p;
  ulong *p_tmp;

  p_tmp = (ulong *) tmp_psp;
  p     = (short *) psp;
  for (i = 0; i < 6; i++)
    p_tmp[i] = ((ulong)p[i]) << 16;
}

#define FAST_QUANT

/* Bug-fixed version (big-little endian problem) */
static void
quant_pred_state(PRED_STATUS *psp, TMP_PRED_STATUS *tmp_psp)
{
    int i;
    short *p1;
    ulong *p2_tmp;

#ifdef	FAST_QUANT
    p1 = (short *) psp;
    p2_tmp = (ulong *)tmp_psp;

    for (i=0; i<MAX_PRED_BINS*6;i++)
      p1[i] = (short) (p2_tmp[i]>>16);
	    
#else
    for (i=0; i<MAX_PRED_BINS; i++) {
      p1 = (short *) &psp[i];
      p2_tmp = (ulong *)tmp_psp;
      {
        int j
          for (j=0; j<6; j++)
            p1[j] = (short) (p2_tmp[i]>>16); /* Is this a bug?!: p2_tmp[i] is wrong. p2_tmp[i][j] is right. P. Lauber */
      }
    }
#endif
}

static void QuantisationPredictorState(PRED_STATUS *psp, TMP_PRED_STATUS *tmp_psp)
{
  int i;
  short *p;
  ulong *p_tmp;

  p_tmp = (ulong *) tmp_psp;
  p     = (short *) psp;
  for (i = 0; i < 6; i++)
    p[i] = (short) (p_tmp[i] >> 16);
}

/********************************************************************************
 *** FUNCTION: reset_pred_state()						*
 ***										*
 ***    reset predictor state variables						*
 ***										*
 ********************************************************************************/
void
reset_pred_state(PRED_STATUS *psp)
{
    psp->r[0] = Q_ZERO;
    psp->r[1] = Q_ZERO;
    psp->kor[0] = Q_ZERO;
    psp->kor[1] = Q_ZERO;
    psp->var[0] = Q_ONE;
    psp->var[1] = Q_ONE;
}


/********************************************************************************
 *** FUNCTION: init_pred_stat()							*
 ***										*
 ***    initialisation of all predictor parameter				*
 ***										*
 ********************************************************************************/
void
init_pred_stat(PRED_STATUS *psp, int grad, float alpha, float a, float b)
{
    static int first_time = 1;

    /* Test of parameters */

    if(grad<0 || grad>MAX_PGRAD) {
	fprintf(stderr,"\n\n ****** error in routine init_pred_stat ******\n");
	fprintf(stderr,"\nwrong predictor order: %d\n",grad);
	fprintf(stderr,"range of allowed values: 0 ... %d (=MAX_PGRAD)\n\n",MAX_PGRAD);
	CommonExit(1,"");
    }
    if(alpha<0 || alpha>=1) {
	fprintf(stderr,"\n\n ****** error in routine init_pred_stat ******\n");
	fprintf(stderr,"\nwrong time constant alpha: %e\n",alpha);
	fprintf(stderr,"range of allowed values: 0 ... 1\n\n");
	CommonExit(1,"");
    }
    if(a<0 || a>1) {