psycho_4.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "common.h"
#include "options.h"
#include "encoder.h"
#include "mem.h"
#include "fft.h"
#include "ath.h"
#include "psycho_4.h"

/****************************************************************
PSYCHO_4 by MFC Feb 2003

This is a cleaned up implementation of psy model 2.
This is basically because I was sick of the inconsistencies between
the notation in the ISO docs and in the sourcecode.

I've nicked a bunch of stuff from LAME to make this a bit easier to grok
- ATH values (this also overcomes the lack of mpeg-2 tables
  which meant that LSF never had proper values)
- freq2bark() to convert frequencies directly to bark values.
- spreading_function() isolated the calculation of the spreading function.
  Basically the same code as before, just isolated in its own function.
  LAME seem to does some extra tweaks to the ISO1117s model.
  Not really sure if they help or hinder, so I've commented them out (#ifdef LAME)

NB: Because of some of the tweaks to bark value calculation etc, it is now possible
to have 64 CBANDS. There's no real limit on the actual number of paritions. 
I wonder if it's worth experimenting with really higher numbers? Probably won't make
that much difference to the final SNR values, but it's something worth trying
    Maybe CBANDS should be a dynamic value, calculated by the psycho_init function
    CBANDS definition has been changed in encoder.h from 63 to 64

****************************************************************/


/* 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;

/* NMT is a constant 5.5dB. ISO11172 Sec D.2.4.h */
static double NMT = 5.5;

/* The index into this array is a bark value 
   This array gives the 'minval' values from ISO11172 Tables D.3.x */
static FLOAT minval[27] = {
  0.0, /* bark = 0 */
  20.0, /* 1 */
  20.0, /* 2 */
  20.0, /* 3 */
  20.0, /* 4 */
  20.0, /* 5 */
  17.0, /* 6 */
  15.0, /* 7 */
  10.0, /* 8 */
  7.0,  /* 9 */
  4.4,  /* 10 */
  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, 4.5,   /* 11 - 25 */
  3.5 /* 26 */
};


static FLOAT *grouped_c, *grouped_e, *nb, *cb, *tb, *ecb, *bc;
static FLOAT *wsamp_r, *phi, *energy;
static FLOAT *c, *bark, *thr;
static F32 *snrtmp;

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

#define TRIGTABLESIZE 3142
#define TRIGTABLESCALE 1000.0
static FLOAT cos_table[TRIGTABLESIZE];
static FLOAT sin_table[TRIGTABLESIZE];
void psycho_4_trigtable_init(void) {

  int i;
  for (i=0;i<TRIGTABLESIZE;i++) {
    cos_table[i] = cos((double)i/TRIGTABLESCALE);
    sin_table[i] = sin((double)i/TRIGTABLESCALE);
  }
}

INLINE FLOAT psycho_4_cos(FLOAT phi) {
  int index;
  int sign=1;

  index = (int)(fabs(phi) * TRIGTABLESCALE);
  while (index>=TRIGTABLESIZE) {
    index -= TRIGTABLESIZE;
    sign*=-1;
  }
  return(sign * cos_table[index]);
}

INLINE FLOAT psycho_4_sin(FLOAT phi) {
  int index;
  int sign=1;

  index = (int)(fabs(phi) * TRIGTABLESCALE);
  while (index>=TRIGTABLESIZE) {
    index -= TRIGTABLESIZE;
    sign*=-1;
  }
  if (phi<0)
    return(-1 * sign * sin_table[index]);
  return(sign * sin_table[index]);
}


void psycho_4 (short int *buffer, short int savebuf[1056], int chn,
		double *smr, double sfreq, options *glopts)
/* to match prototype : FLOAT args are always double */
{
  unsigned int run, i, j, k;
  FLOAT r_prime, phi_prime;
  FLOAT npart, epart;

  if (init == 0) {
    psycho_4_init (sfreq, glopts);
    init++;
  }

  for (run = 0; run < 2; run++) {
    /* Net offset is 480 samples (1056-576) for layer 2; this is because one must
       stagger input data by 256 samples to synchronize psychoacoustic model with
       filter bank outputs, then stagger so that center of 1024 FFT window lines 
       up with center of 576 "new" audio samples.                                
       
       flush = 384*3.0/2.0;  = 576
       syncsize = 1056;
       sync_flush = syncsize - flush;   480
       BLKSIZE = 1024                                              */
    for (j = 0; j < 480; j++) {
      savebuf[j] = savebuf[j + 576];
      wsamp_r[j] = window[j] * ((FLOAT) savebuf[j]);
    }
    for (; j < 1024; j++) {
      savebuf[j] = *buffer++;
      wsamp_r[j] = window[j] * ((FLOAT) savebuf[j]);
    }
    for (; j < 1056; j++)
      savebuf[j] = *buffer++;


    /* Compute FFT */
    psycho_2_fft (wsamp_r, energy, phi);

    /* calculate the unpredictability measure, given energy[f] and phi[f] 
       (the age pointers [new/old/oldest] are reset automatically on the second pass */
    {
      if (new == 0) {
	new = 1;
	oldest = 1;
      } else {
	new = 0;
	oldest = 0;
      }
      if (old == 0)
	old = 1;
      else
	old = 0;
    }

    for (j = 0; j < HBLKSIZE; j++) {
#ifdef NEWATAN
      double temp1, temp2, temp3;
      r_prime = 2.0 * r[chn][old][j] - r[chn][oldest][j];
      phi_prime = 2.0 * phi_sav[chn][old][j] - phi_sav[chn][oldest][j];

      r[chn][new][j] = sqrt ((double) energy[j]);
      phi_sav[chn][new][j] = phi[j];	
  
      {
	temp1 =
	  r[chn][new][j] * psycho_4_cos(phi[j]) -
	  r_prime * psycho_4_cos(phi_prime);
	temp2 =
	  r[chn][new][j] * psycho_4_sin(phi[j]) -
	  r_prime * psycho_4_sin(phi_prime); 
	//fprintf(stdout,"[%5.2f %5.2f] [%5.2f %5.2f]\n",temp1, mytemp1, temp2, mytemp2);

      }


      temp3 = r[chn][new][j] + fabs ((double) r_prime);
      if (temp3 != 0)
	c[j] = sqrt (temp1 * temp1 + temp2 * temp2) / temp3;
      else
	c[j] = 0;
#else
      double temp1, temp2, temp3;
      r_prime = 2.0 * r[chn][old][j] - r[chn][oldest][j];
      phi_prime = 2.0 * phi_sav[chn][old][j] - phi_sav[chn][oldest][j];

      r[chn][new][j] = sqrt ((double) energy[j]);
      phi_sav[chn][new][j] = phi[j];	


      temp1 =
	r[chn][new][j] * cos ((double) phi[j]) -
	r_prime * cos ((double) phi_prime);
      temp2 =
	r[chn][new][j] * sin ((double) phi[j]) -
	r_prime * sin ((double) phi_prime);      

      temp3 = r[chn][new][j] + fabs ((double) r_prime);
      if (temp3 != 0)
	c[j] = sqrt (temp1 * temp1 + temp2 * temp2) / temp3;
      else
	c[j] = 0;
#endif
    }

    /* For each partition, sum all the energy in that partition - grouped_e
       and calculated the energy-weighted unpredictability measure - grouped_c
       ISO 11172 Section D.2.4.e */
    for (j = 1; j < CBANDS; j++) {
      grouped_e[j] = 0;
      grouped_c[j] = 0;
    }
    grouped_e[0] = energy[0];
    grouped_c[0] = energy[0] * c[0];
    for (j = 1; j < HBLKSIZE; j++) {
      grouped_e[partition[j]] += energy[j];
      grouped_c[partition[j]] += energy[j] * c[j];
    }

    /* convolve the grouped energy-weighted unpredictability measure             
       and the grouped energy with the spreading function
       ISO 11172 D.2.4.f */
    for (j = 0; j < CBANDS; j++) {
      ecb[j] = 0;
      cb[j] = 0;
      for (k = 0; k < CBANDS; k++) {
	if (s[j][k] != 0.0) {
	  ecb[j] += s[j][k] * grouped_e[k];
	  cb[j] += s[j][k] * grouped_c[k];
	}
      }
      if (ecb[j] != 0)
	cb[j] = cb[j] / ecb[j];
      else
	cb[j] = 0;
    }

    /* Convert cb to tb (the tonality index) 
       ISO11172 SecD.2.4.g */
    for (i=0;i<CBANDS;i++) {
      if (cb[i] < 0.05)
	cb[i] = 0.05;
      else if (cb[i] > 0.5)
	cb[i] = 0.5;
      tb[i] = -0.301029996 - 0.434294482 * log((double) cb[i]);
    }
      

    /* Calculate the required SNR for each of the frequency partitions 
       ISO 11172 Sect D.2.4.h */
    for (j = 0; j < CBANDS; j++) {
      FLOAT SNR, SNRtemp;
      SNRtemp = tmn[j] * tb[j] + NMT * (1.0 - tb[j]);
      SNR = MAX(SNRtemp, minval[(int)cbval[j]]);
      bc[j] = exp ((double) -SNR * LN_TO_LOG10);
    }

    /* Calculate the permissible noise energy level in each of the frequency     
       partitions. 
       This section used to have pre-echo control but only for LayerI 
       ISO 11172 Sec D.2.4.k - Spread the threshold energy over FFT lines */
    for (j = 0; j < CBANDS; j++) {
      if (rnorm[j] && numlines[j])
	nb[j] = ecb[j] * bc[j] / (rnorm[j] * numlines[j]);
      else
	nb[j] = 0;
    }

    /* ISO11172 Sec D.2.4.l - thr[] the final energy threshold of audibility */
    for (j = 0; j < HBLKSIZE; j++) 
      thr[j] = MAX(nb[partition[j]], ath[j]);

    /* Translate the 512 threshold values to the 32 filter bands of the coder  
       Using ISO 11172 Table D.5 and Section D.2.4.n */
    for (j = 0; j < 193; j += 16) {
      /* WIDTH = 0 */
      npart = 60802371420160.0;
      epart = 0.0;
      for (k = 0; k < 17; k++) {
	if (thr[j + k] < npart)
	  npart = thr[j + k]; /* For WIDTH==0, find the minimum noise, and 
			         later multiply by the number of indexes i.e. 17 */
	epart += energy[j + k];
      }
      snrtmp[run][j / 16] = 4.342944819 * log((double)(epart/(npart*17.0)));
    }
    for (j = 208; j < (HBLKSIZE - 1); j += 16) {
      /* WIDTH = 1 */
      npart = 0.0;
      epart = 0.0;
      for (k = 0; k < 17; k++) {
	npart += thr[j + k]; /* For WIDTH==1, sum the noise */
	epart += energy[j + k];
      }
      snrtmp[run][j / 16] = 4.342944819 * log ((double) (epart/npart));
    }
  }

  /* Pick the maximum value of the two runs ISO 11172 Sect D.2.1 */
  for (i = 0; i < 32; i++) 
    smr[i] = MAX(snrtmp[0][i], snrtmp[1][i]);
  
}

/********************************
 * init psycho model 2
 ********************************/
void psycho_4_init (double sfreq, options *glopts)
{
  int i, j;

  /* Allocate memory for all the static variables */
  psycho_4_allocmem();

  /* Set up the SIN/COS tables */
  psycho_4_trigtable_init();

  /* calculate HANN window coefficients */
  for (i = 0; i < BLKSIZE; i++)
    window[i] = 0.5 * (1 - cos (2.0 * PI * (i - 0.5) / BLKSIZE));

  /* For each FFT line from 0(DC) to 512(Nyquist) calculate
     - bark          : the bark value of this fft line
     - ath        : the absolute threshold of hearing for this line [ATH]  

     Since it is a 1024 point FFT, each line in the fft  corresponds 
     to   1/1024 of the total frequency.    
     Line 0 should correspond to DC - which doesn't really have a ATH afaik
     Line 1 should be 1/1024th of the Sampling Freq
     Line 512 should be the nyquist freq  */
  for (i=0; i<HBLKSIZE; i++) {
    FLOAT freq = i * sfreq/BLKSIZE;
    bark[i] = freq2bark(freq);
    /* The ath tables in the dist10 code seem to be a little out of kilter. 
       they seem to start with index 0 corresponding to (sampling freq)/1024.
       When in doubt, i'm going to assume that the dist10 code is wrong. MFC Feb2003  */
    ath[i] = ATH_energy(freq,glopts->athlevel);
    //fprintf(stdout,"%.2f ",ath[i]);
  }  
 

  /* Work out the partitions
     Starting from line 0, all lines within 0.33 of the starting
     bark are added to the same partition. When a line is greater
     by 0.33 of a bark, start a new partition.  */
  int partition_count = 0; /* keep a count of the partitions */
  int cbase = 0; /* current base index for the bark range calculation */
  for (i=0;i<HBLKSIZE;i++) {
    if ((bark[i] - bark[cbase]) > 0.33) { /* 1/3 critical band? */
      /* this frequency line is too different from the starting line,
	 (in terms of the bark distance)
	 so close that previous partition, and make this line the first
	 member of the next partition */
      cbase = i; /* Start the new partition from this frequency */
      partition_count++;
    } 
    /* partition[i] tells us which partition the i'th frequency line is in */
    partition[i] = partition_count;
    /* keep a count of how many frequency lines are in each partition */
    numlines[partition_count]++;
  }

  /* For each partition within the frequency space, 
     calculate the average bark value - cbval [central bark value] */
  for (i=0;i<HBLKSIZE;i++) 
    cbval[partition[i]] += bark[i]; /* sum up all the bark values */
  for (i=0;i<CBANDS;i++) {
    if (numlines[i] != 0)
      cbval[i] /= numlines[i]; /* divide by the number of values */
    else {
      cbval[i]=0; /* this isn't a partition */
    }
  }
  

  /* Calculate the spreading function. ISO 11172 Section D.2.3 */
  for (i=0;i<CBANDS;i++) {
    for (j=0;j<CBANDS;j++) {
      s[i][j] = psycho_4_spreading_function( 1.05 * (cbval[i] - cbval[j]) );
      rnorm[i] += s[i][j]; /* sum the spreading function values for each partition so that
				they can be normalised later on */
    }
  }
  
  /* Calculate Tone Masking Noise values. ISO 11172 Tables D.3.x */
  for (j = 0; j < CBANDS; j++)
    tmn[j] = MAX(15.5+cbval[j], 24.5);


  if (glopts->verbosity > 10) {
    /* Dump All the Values to STDOUT */
    int wlow, whigh=0;
    int ntot=0;
    fprintf(stdout,"psy model 4 init\n");
    fprintf(stdout,"index \tnlines \twlow \twhigh \tbval \tminval \ttmn\n");
    for (i=0;i<CBANDS;i++) 
      if (numlines[i] != 0) {
      wlow = whigh+1;
      whigh = wlow + numlines[i] - 1;
      fprintf(stdout,"%i \t%i \t%i \t%i \t%5.2f \t%4.2f \t%4.2f\n",i+1, numlines[i],wlow, whigh, cbval[i],minval[(int)cbval[i]],tmn[i]);
      ntot += numlines[i];
      }
    fprintf(stdout,"total lines %i\n",ntot);
    exit(0);
  }
}

/* The spreading function.  Values returned in units of energy
   Argument 'bark' is the difference in bark values between the
   centre of two partitions.
   This has been taken from LAME. MFC Feb 2003 */
FLOAT8 psycho_4_spreading_function(FLOAT8 bark) {

    FLOAT8 tempx,x,tempy,temp;
    tempx = bark;
#ifdef LAME
    /* MP3 standard actually spreads these values a little more */
    if (tempx>=0) tempx *= 3;
    else tempx *=1.5;
#endif

    if(tempx>=0.5 && tempx<=2.5)
        {
            temp = tempx - 0.5;
            x = 8.0 * (temp*temp - 2.0 * temp);
        }
    else x = 0.0;
    tempx += 0.474;
    tempy = 15.811389 + 7.5*tempx - 17.5*sqrt(1.0+tempx*tempx);

    if (tempy <= -60.0) return  0.0;

    tempx = exp( (x + tempy)*LN_TO_LOG10 );

#ifdef LAME
    /* I'm not sure where the magic value of 0.6609193 comes from.
       toolame will just keep using the rnorm to normalise the spreading function
       MFC Feb 2003 */
    /* Normalization.  The spreading function should be normalized so that:
         +inf
           /
           |  s3 [ bark ]  d(bark)   =  1
           /
         -inf
    */
    tempx /= .6609193;
#endif
    return tempx;

}

void psycho_4_allocmem() {
  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");
  tb = (FLOAT *) mem_alloc (sizeof (FCB), "tb");
  ecb = (FLOAT *) mem_alloc (sizeof (FCB), "ecb");
  bc = (FLOAT *) mem_alloc (sizeof (FCB), "bc");
  wsamp_r = (FLOAT *) mem_alloc (sizeof (FBLK), "wsamp_r");
  phi = (FLOAT *) mem_alloc (sizeof (FBLK), "phi");
  energy = (FLOAT *) mem_alloc (sizeof (FBLK), "energy");
  c = (FLOAT *) mem_alloc (sizeof (FHBLK), "c");
  bark = (FLOAT *) mem_alloc (sizeof (FHBLK), "bark");
  thr = (FLOAT *) mem_alloc (sizeof (FHBLK), "thr");
  snrtmp = (F32 *) mem_alloc (sizeof (F2_32), "snrtmp");

  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");
  ath = (FLOAT *) mem_alloc (sizeof (FHBLK), "ath");
  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");

}