psy.c

MPEG 2的音频编码软件。喜欢多媒体的开发人员可以看看。

/**********************************************************************
 * ISO MPEG Audio Subgroup Software Simulation Group (1996)
 * ISO 13818-3 MPEG-2 Audio Multichannel Encoder
 *
 * $Id: psy.c 1.7 1996/02/12 07:13:35 rowlands Exp $
 *
 * $Log: psy.c $
 * Revision 1.7  1996/02/12 07:13:35  rowlands
 * Release following Munich meeting
 *
 **********************************************************************/

/**********************************************************************
 *   date   programmers         comment                               *
 * 2/25/91  Davis Pan           start of version 1.0 records          *
 * 5/10/91  W. Joseph Carter    Ported to Macintosh and Unix.         *
 * 7/10/91  Earle Jennings      Ported to MsDos.                      *
 *                              replace of floats with FLOAT          *
 * 2/11/92  W. Joseph Carter    Fixed mem_alloc() arg for "absthr".   *
 **********************************************************************/

#include "common.h"
#include "encoder.h"

void
psycho_anal(
	double *buffer,
	short int *savebuf,
	int chn,
	int lay,
	float *snr32,
	double sfreq /* to match prototype : float args are always double */
) {
 unsigned int   i, j, k;
 FLOAT          r_prime, phi_prime;
 FLOAT          freq_mult, bval_lo, minthres, sum_energy;
 double         tb, temp1, temp2, temp3;

/* The static variables "r", "phi_sav", "new", "old" and "oldest" have    */
/* to be remembered for the unpredictability measure.  For "r" and        */
/* "phi_sav", the first index from the left is the channel select and     */
/* the second index is the "age" of the data.                             */

 static int     new = 0, old = 1, oldest = 0;
 static int     init = 0, flush, syncsize, sfreq_idx;

/* The following static variables are constants.                           */

 static double  nmt = 5.5;

 static FLOAT   crit_band[27] = {0,  100,  200, 300, 400, 510, 630,  770,
                               920, 1080, 1270,1480,1720,2000,2320, 2700,
                              3150, 3700, 4400,5300,6400,7700,9500,12000,
                             15500,25000,30000};

 static FLOAT   bmax[27] = {20.0, 20.0, 20.0, 20.0, 20.0, 17.0, 15.0,
                            10.0,  7.0,  4.4,  4.5,  4.5,  4.5,  4.5,
                             4.5,  4.5,  4.5,  4.5,  4.5,  4.5,  4.5,
                             4.5,  4.5,  4.5,  3.5,  3.5,  3.5};

/* The following pointer variables point to large areas of memory         */
/* dynamically allocated by the mem_alloc() function.  Dynamic memory     */
/* allocation is used in order to avoid stack frame or data area          */
/* overflow errors that otherwise would have occurred at compile time     */
/* on the Macintosh computer.                                             */

 FLOAT          *grouped_c, *grouped_e, *nb, *cb, *ecb, *bc;
 FLOAT          *wsamp_r, *wsamp_i, *phi, *energy;
 FLOAT          *c, *fthr;
 F32            *snrtmp;

 static int     *numlines;
 static int     *partition;
 static FLOAT   *cbval, *rnorm;
 static FLOAT   *window;
 static FLOAT   *absthr;
 static double  *tmn;
 static FCB     *s;
 static FHBLK   *lthr;
 static F2HBLK  *r, *phi_sav;

/* These dynamic memory allocations simulate "automatic" variables        */
/* placed on the stack.  For each mem_alloc() call here, there must be    */
/* a corresponding mem_free() call at the end of this function.           */

 grouped_c = (FLOAT *) mem_alloc(sizeof(FCB), "grouped_c");
 grouped_e = (FLOAT *) mem_alloc(sizeof(FCB), "grouped_e");
 nb = (FLOAT *) mem_alloc(sizeof(FCB), "nb");
 cb = (FLOAT *) mem_alloc(sizeof(FCB), "cb");
 ecb = (FLOAT *) mem_alloc(sizeof(FCB), "ecb");
 bc = (FLOAT *) mem_alloc(sizeof(FCB), "bc");
 wsamp_r = (FLOAT *) mem_alloc(sizeof(FBLK), "wsamp_r");
 wsamp_i = (FLOAT *) mem_alloc(sizeof(FBLK), "wsamp_i");
 phi = (FLOAT *) mem_alloc(sizeof(FBLK), "phi");
 energy = (FLOAT *) mem_alloc(sizeof(FBLK), "energy");
 c = (FLOAT *) mem_alloc(sizeof(FHBLK), "c");
 fthr = (FLOAT *) mem_alloc(sizeof(FHBLK), "fthr");
 snrtmp = (F32 *) mem_alloc(sizeof(F2_32), "snrtmp");

 if(init==0){

/* These dynamic memory allocations simulate "static" variables placed    */
/* in the data space.  Each mem_alloc() call here occurs only once at     */
/* initialization time.  The mem_free() function must not be called.      */

     numlines = (int *) mem_alloc(sizeof(ICB), "numlines");
     partition = (int *) mem_alloc(sizeof(IHBLK), "partition");
     cbval = (FLOAT *) mem_alloc(sizeof(FCB), "cbval");
     rnorm = (FLOAT *) mem_alloc(sizeof(FCB), "rnorm");
     window = (FLOAT *) mem_alloc(sizeof(FBLK), "window");
     absthr = (FLOAT *) mem_alloc(sizeof(FHBLK), "absthr");
     tmn = (double *) mem_alloc(sizeof(DCB), "tmn");
     s = (FCB *) mem_alloc(sizeof(FCBCB), "s");
     lthr = (FHBLK *) mem_alloc(sizeof(F2HBLK), "lthr");
     r = (F2HBLK *) mem_alloc(sizeof(F22HBLK), "r");
     phi_sav = (F2HBLK *) mem_alloc(sizeof(F22HBLK), "phi_sav");

     i = sfreq + 0.5;
     switch(i){
        case 32000: sfreq_idx = 0; break;
        case 44100: sfreq_idx = 1; break;
        case 48000: sfreq_idx = 2; break;
        default:    printf("error, invalid sampling frequency: %d Hz\n",i);
        exit(-1);
     }
     if (verbosity >= 2) printf("absthr[][] sampling frequency index: %d\n",sfreq_idx);
     read_absthr(absthr, sfreq_idx);
     if(lay==1){
        flush = 448;
        syncsize = 1024;
     }
     else {
        flush = 384*3.0/2.0;
        syncsize = 1056;
     }
/* calculate HANN window coefficients */
     for(i=0;i<BLKSIZE;i++)window[i]=0.5*(1-cos(2.0*PI*i/(BLKSIZE-1.0)));
/* reset states used in unpredictability measure */
     for(i=0;i<HBLKSIZE;i++){
        r[0][0][i]=r[1][0][i]=r[0][1][i]=r[1][1][i]=0;
        phi_sav[0][0][i]=phi_sav[1][0][i]=0;
        phi_sav[0][1][i]=phi_sav[1][1][i]=0;
        lthr[0][i] = 60802371420160.0;
        lthr[1][i] = 60802371420160.0;
     }
/*****************************************************************************
 * Initialization: Compute the following constants for use later             *
 *    partition[HBLKSIZE] = the partition number associated with each        *
 *                          frequency line                                   *
 *    cbval[CBANDS]       = the center (average) bark value of each          *
 *                          partition                                        *
 *    numlines[CBANDS]    = the number of frequency lines in each partition  *
 *    tmn[CBANDS]         = tone masking noise                               *
 *****************************************************************************/
/* compute fft frequency multiplicand */
     freq_mult = sfreq/BLKSIZE;
 
/* calculate fft frequency, then bval of each line (use fthr[] as tmp storage)*/
     for(i=0;i<HBLKSIZE;i++){
        temp1 = i*freq_mult;
        j = 1;
        while(temp1>crit_band[j])j++;
        fthr[i]=j-1+(temp1-crit_band[j-1])/(crit_band[j]-crit_band[j-1]);
     }
     partition[0] = 0;
/* temp2 is the counter of the number of frequency lines in each partition */
     temp2 = 1;
     cbval[0]=fthr[0];
     bval_lo=fthr[0];
     for(i=1;i<HBLKSIZE;i++){
        if((fthr[i]-bval_lo)>0.33){
           partition[i]=partition[i-1]+1;
           cbval[partition[i-1]] = cbval[partition[i-1]]/temp2;
           cbval[partition[i]] = fthr[i];
           bval_lo = fthr[i];
           numlines[partition[i-1]] = temp2;
           temp2 = 1;
        }
        else {
           partition[i]=partition[i-1];
           cbval[partition[i]] += fthr[i];
           temp2++;
        }
     }
     numlines[partition[i-1]] = temp2;
     cbval[partition[i-1]] = cbval[partition[i-1]]/temp2;
 
/************************************************************************
 * Now compute the spreading function, s[j][i], the value of the spread-*
 * ing function, centered at band j, for band i, store for later use    *
 ************************************************************************/
     for(j=0;j<CBANDS;j++){
        for(i=0;i<CBANDS;i++){
           temp1 = (cbval[i] - cbval[j])*1.05;
           if(temp1>=0.5 && temp1<=2.5){
              temp2 = temp1 - 0.5;
              temp2 = 8.0 * (temp2*temp2 - 2.0 * temp2);
           }
           else temp2 = 0;
           temp1 += 0.474;
           temp3 = 15.811389+7.5*temp1-17.5*sqrt((double) (1.0+temp1*temp1));
           if(temp3 <= -100) s[i][j] = 0;
           else {
              temp3 = (temp2 + temp3)*LN_TO_LOG10;
              s[i][j] = exp(temp3);
           }
        }
     }

  /* Calculate Tone Masking Noise values */
     for(j=0;j<CBANDS;j++){
        temp1 = 15.5 + cbval[j];
        tmn[j] = (temp1>24.5) ? temp1 : 24.5;
  /* Calculate normalization factors for the net spreading functions */
        rnorm[j] = 0;
        for(i=0;i<CBANDS;i++){
           rnorm[j] += s[j][i];