path: root/src/limiter~.c

/*
 * limiter~: limit/compress signals
 *
 * (c) 1999-2011 IOhannes m zmölnig, forum::fÌr::umlÀute, institute of electronic music and acoustics (iem)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */



/*
  --------------------------------- limiter/compressor ---------------------------------

  for details on how it works watch out for   "http://iem.kug.ac.at/~zmoelnig/pd"
  ...and search for "limiter"

  mail2me4more!n4m8ion : zmoelnig@iem.kug.ac.at
*/

/*
   this is a limiter/compressor-object
   the limiter is based on Falkner's thesis
   "Entwicklung eines digitalen Stereo-limiters mit Hilfe des Signalprozessors DSP56001" pp.14

   2108:forum::fÌr::umlÀute:1999		all rights reserved and no warranties...

   see GNU-license for details
*/

#define LIMIT0 0
#define LIMIT1 1
#define COMPRESS 2

#include "zexy.h"

/* log2 */
#define LN2 .69314718056


/* hmm, where do these values come from exactly?
   we are doing a 3* oversampling, so we need to calculate the samples that are +-1/3 off the current sample
   sinc([13 10 7 4 1 -2 -5 -8 -11]/3) * window
   window=cosine window

*/

/*
#define SINC[4] .822462987
#define SINC[3] .404460777
#define SINC[5] -.188874003
#define SINC[2] -.143239449
#define SINC[6] .087796546
#define SINC[1] .06917082
#define SINC[7] -.041349667
#define SINC[0] -.030578954
#define SINC[8] .013226276
*/

#define BUFSIZE 128
#define XTRASAMPS 9
#define TABLESIZE 512 /* compressor table */

static t_sample SINC[9];

#define PI  3.1415926535897932384626433832795029L  /* pi */

static void init_sinc(void)
{
  /*  calculate the sinc (windowed with a cosine) */
  int i=0;
  for(i=0; i<9; i++) {
    long double t=(3.*i - 11.)/3.;
    long double v=cos(t*PI/10.)*sin(PI*t)/(PI*t);
    SINC[i]=v;
  }
}

/* ------------------------------------------------------------------------------------ */
/* first define the structs... */

static t_class *limiter_class;

typedef struct _limctl {
  /* variables changed by user */
  t_float limit;
  t_float hold_samples;
  t_float change_of_amplification;
} t_limctl;

typedef struct _cmpctl {
  t_float treshold,
          ratio;		/* uclimit is the very same is the limiter1-limit (decalculated relative to our treshold) */
  t_float uclimit,
          climit_inverse;	/* climit == compressed limit (uclimit == uncompressed limit) */

  t_float limiter_limit;		/* start limiting (stop compressing); == tresh/limit; */

  t_float treshdB, oneminusratio;
} t_cmpctl;

typedef struct _inbuf {
  t_sample*	ringbuf;
  int		buf_position;
} t_inbuf;

typedef struct _limiter {
  t_object	x_obj;

  int		number_of_inlets, s_n;

  /* variables changed by process */
  t_sample	amplification;
  t_float	samples_left, still_left;

  int		mode;

  t_limctl	*val1, *val2;
  t_cmpctl	*cmp;

  /* note :	limit is not the same for val1 & val2 :
   *			at val1 it is the limit of the INPUT_VALUE
   *			at val2 it is the limit for the AMPLIFICATION (in fact it is abs_limit1/abs_limit2)
   */

  t_inbuf*	in;
  int		buf_size;

} t_limiter;

/* ------------------------------------------------------------------------------------ */
/* then do the message - thing */

/* do the user settings */

/* calcs */
static t_float calc_holdsamples(t_float htime, int buf)
{
  /* hold_time must be greater than buffer_time to make sure that any peak_sample is amplified with its own factor */
  t_float min_hold = buf / sys_getsr();
  return (0.001 * sys_getsr() * ((htime > min_hold)?htime:((
                                   min_hold > 50)?min_hold:50)));
}

static t_float calc_coa(t_float hlife)
{
  return (exp(LN2 * 1000 / (((hlife > 0)?hlife:15) * sys_getsr())));
}

static void set_uclimit(t_limiter *x)
{
  t_cmpctl *c = x->cmp;
  t_float limit = x->val1->limit, limitdB = rmstodb(limit), ratio = c->ratio,
          tresh = c->treshold, treshdB = rmstodb(tresh);

  c->climit_inverse  = limit / tresh;
  c->uclimit = tresh / dbtorms(treshdB+(limitdB - treshdB)/ratio);

  c->treshdB = treshdB;
  c->oneminusratio = 1. - ratio;
}

/* settings */

static void set_treshold(t_limiter *x, t_float treshold)
{
  t_cmpctl *c = x->cmp;
  t_float tresh = dbtorms (treshold);
  if (tresh > x->val1->limit) {
    tresh = x->val1->limit;
  }

  c->treshold = tresh;

  set_uclimit(x);
}

static void set_ratio(t_limiter *x, t_float ratio)
{
  if (ratio < 0) {
    ratio = 1;
  }
  x->cmp->ratio = ratio;

  set_uclimit(x);
}

static void set_mode(t_limiter *x, t_float mode)
{
  int modus = mode;

  switch (modus) {
  case LIMIT0:
    x->mode = LIMIT0;
    break;
  case LIMIT1:
    x->mode = LIMIT1;
    break;
  case COMPRESS:
    x->mode = COMPRESS;
    break;
  default:
    x->mode = LIMIT0;
    break;
  }
}

static void set_LIMIT(t_limiter *x)
{
  set_mode(x, LIMIT0);
}

static void set_CRACK(t_limiter *x)
{
  set_mode(x, LIMIT1);
}

static void set_COMPRESS(t_limiter *x)
{
  set_mode(x, COMPRESS);
}

static void set_bufsize(t_limiter *x, int size)
{
  /* this is really unneeded...and for historical reasons only */
  if (size < BUFSIZE) {
    size = BUFSIZE;
  }
  x->buf_size = size + XTRASAMPS;
}

static void set_limit(t_limiter *x, t_floatarg limit)
{
  if (limit < 0.00001) {
    limit = 100;
  }
  x->val1->limit = dbtorms(limit);

  if (x->val1->limit < x->cmp->treshold) {
    x->cmp->treshold = x->val1->limit;
  }
  set_uclimit(x);
}

static void set_limits(t_limiter *x, t_floatarg limit1, t_floatarg limit2)
{
  t_float lim1, lim2;

  if (limit1 < 0.00001) {
    limit1 = 100;
  }

  lim1 = dbtorms(limit1);
  lim2 = dbtorms(limit2);

  if (lim2 < lim1) {
    lim2 = 2*lim1;	/* this is to prevent lim2 (which should trigger the FAST regulation) */
    x->mode = 0;	/* to underrun the SLOW regulation; this would cause distortion */
  }

  x->val1->limit = lim1;
  x->val2->limit = lim1/lim2;

  if (lim1 < x->cmp->treshold) {
    x->cmp->treshold = lim1;
  }
  set_uclimit(x);
}

static void set1(t_limiter *x, t_floatarg limit, t_floatarg hold,
                 t_floatarg release)
{
  t_float lim = dbtorms(limit);

  x->val1->limit = (lim > 0)?lim:1;
  x->val1->hold_samples = calc_holdsamples(hold, x->buf_size);
  x->val1->change_of_amplification = calc_coa(release);

  if (lim < x->cmp->treshold) {
    x->cmp->treshold = lim;
  }
  set_uclimit(x);
}


static void set2(t_limiter *x, t_floatarg limit, t_floatarg hold,
                 t_floatarg release)
{
  t_float lim = dbtorms(limit);
  x->val2->limit = (lim > x->val1->limit)?(x->val1->limit/lim):.5;
  x->val2->hold_samples = calc_holdsamples(hold, x->buf_size);
  x->val2->change_of_amplification = calc_coa(release);
}



static void set_compressor(t_limiter *x, t_floatarg limit,
                           t_floatarg treshold, t_floatarg ratio)
{
  t_cmpctl *c = x->cmp;
  t_float lim = dbtorms(limit);
  t_float tresh = dbtorms(treshold);

  if ((limit == 0) && (treshold == 0) && (ratio == 0)) {
    set_mode(x, COMPRESS);
    return;
  }

  if (tresh > lim) {
    tresh = lim;
  }
  if (ratio < 0.) {
    ratio = 1.;
  }

  c->ratio = ratio;
  x->val1->limit = lim;
  c->treshold = tresh;
  set_uclimit(x);

  set_mode(x, COMPRESS);
}

static void reset(t_limiter *x)
{
  x->amplification = 1.;
}

/* verbose */
static void status(t_limiter *x)
{
  t_limctl *v1 = x->val1;
  t_limctl *v2 = x->val2;
  t_cmpctl *c = x->cmp;

  t_float sr = sys_getsr() / 1000.;

  switch (x->mode) {
  case LIMIT1:
    post("%d-channel crack-limiter @ %fkHz\n"
         "\noutput-limit\t= %fdB\nhold1\t\t= %fms\nrelease1\t= %fms\ncrack-limit\t= %fdB\nhold2\t\t= %fms\nrelease2\t= %fms\n"
         "\namplify\t\t= %fdB\n",
         x->number_of_inlets, sr,
         rmstodb(v1->limit), (v1->hold_samples) / sr,
         LN2 / (log(v1->change_of_amplification) * sr),
         rmstodb(v1->limit / v2->limit), (v2->hold_samples) / sr,
         LN2 / (log(v2->change_of_amplification) * sr),
         x->amplification);
    break;
  case LIMIT0:
    post("%d-channel limiter @ %fkHz\n"
         "\noutput-limit\t= %fdB\nhold\t\t= %fms\nrelease\t\t= %fms\n"
         "\namplify\t\t= %fdB\n",
         x->number_of_inlets, sr,
         rmstodb(v1->limit), (v1->hold_samples) / sr,
         LN2 / (log(v1->change_of_amplification) * sr),
         rmstodb(x->amplification));
    break;
  case COMPRESS:
    post("%d-channel compressor @ %fkHz\n"
         "\noutput-limit\t= %fdB\ntreshold\t= %fdB\ninput-limit\t= %f\nratio\t\t= 1:%f\n"
         "\nhold\t\t= %fms\nrelease\t\t= %fms\n"
         "\namplify\t\t= %fdB\n",
         x->number_of_inlets, sr,
         rmstodb(c->treshold * c->climit_inverse), rmstodb(c->treshold),
         rmstodb(c->treshold / c->uclimit), 1./c->ratio,
         (v1->hold_samples) / sr, LN2 / (log(v1->change_of_amplification) * sr),
         rmstodb(x->amplification));
  }
}

static void limiter_tilde_helper(t_limiter *x)
{
  post("\n\n"HEARTSYMBOL" %d-channel limiter-object: mode %d",
       x->number_of_inlets, x->mode);
  poststring("\n'mode <mode>'\t\t\t: (0_limiter, 1_crack-limiter, 2_compressor)");
  poststring("\n'LIMIT'\t\t\t\t: set to LIMITer");
  poststring("\n'CRACK'\t\t\t\t: set to CRACK-limiter");
  poststring("\n'COMPRESS'\t\t\t\t: set to COMPRESSor");

  switch (x->mode) {
  case LIMIT0:
    poststring("\n'limit <limit>'\t\t\t: set limit (in dB)"
               "\n'set <limit><htime><rtime>'\t: set limiter");
    break;
  case LIMIT1:
    poststring("\n'limits <limit1><limit2>'\t: set limits (in dB)"
               "\n'set  <limit1><htime1><rtime1>'\t: set limiter 1"
               "\n'set2 <limit2><htime2><rtime2>'\t: set crack-limiter");
    break;
  case COMPRESS:
    poststring("\n'ratio <compressratio>'\t\t: set compressratio (Ŝ0.5Ŝ instead of Ŝ1:2Ŝ)"
               "\n'treshold <treshold>'\t\t: set treshold of the compressor"
               "\n'compress <limit><treshold><ratio>'\t: set compressor"
               "\n..........note that <limit> is the same for COMPRESSOR and LIMITER..........");
    break;
  default:
    break;
  }
  poststring("\n'print'\t\t\t\t: view actual settings"
             "\n'help'\t\t\t\t: view this\n");
  poststring("\ncreating arguments are :\n"
             "\"limiter~ [<in1> [<in2> [<in3> [...]]]]\":	<in*> may be anything\n");
  endpost();
}


/* ------------------------------------------------------------------------------------ */
/* now do the dsp - thing							                                                  */
/* ------------------------------------------------------------------------------------ */

static t_int *oversampling_maxima(t_int *w)
{
  t_limiter *x = (t_limiter *)w[1];
  t_inbuf *buf = (t_inbuf *)w[2];
  t_sample *in	 = (t_sample *)w[3];
  t_sample *out = (t_sample *)w[4];

  int n = x->s_n;
  int bufsize = x->buf_size;

  int i = buf->buf_position;

  t_sample *vp = buf->ringbuf, *ep = vp + bufsize, *bp = vp + XTRASAMPS + i;

  i += n;

  while (n--) {
    t_sample os1, os2, max;
    t_sample last4, last3, last2, last1, sinccurrent, current, next1, next2,
             next3, next4;

    if (bp == ep) {
      vp[0] = bp[-9];
      vp[1] = bp[-8];
      vp[2] = bp[-7];
      vp[3] = bp[-6];
      vp[4] = bp[-5];
      vp[5] = bp[-4];
      vp[6] = bp[-3];
      vp[7] = bp[-2];
      vp[8] = bp[-1];

      bp = vp + XTRASAMPS;
      i -= bufsize - XTRASAMPS;
    }


    last4 = bp[-8];
    last3 = bp[-7];
    last2 = bp[-6];
    last1 = bp[-5];
    current = bp[-4];
    next1 = bp[-3];
    next2 = bp[-2];
    next3 = bp[-1];
    next4 = bp[0];

    sinccurrent = SINC[4] * current;

    os1= fabsf(SINC[0] * last4 +
               SINC[1] * last3 +
               SINC[2] * last2 +
               SINC[3] * last1 +
               sinccurrent +
               SINC[5] * next1 +
               SINC[6] * next2 +
               SINC[7] * next3 +
               SINC[8] * next4);

    os2= fabsf(SINC[0] * next4 +
               SINC[1] * next3 +
               SINC[2] * next2 +
               SINC[3] * next1 +
               sinccurrent +
               SINC[5] * last1 +
               SINC[6] * last2 +
               SINC[7] * last3 +
               SINC[8] * last4);

    max = fabsf(current);

#if 0
    if(max>1. || os1>1. || os2>1.)
      post("%f %f %f\t%f %f %f %f %f %f %f %f %f", max, os1, os2,
           last4,
           last3,
           last2,
           last1,
           current,
           next1,
           next2,
           next3,
           next4
          );
#endif
    if (max < os1) {
      max = os1;
    }
    if (max < os2) {
      max = os2;
    }

    *bp++ = *in++;
    if (*out++ < max) {
      *(out-1) = max;
    }
  }
  buf->buf_position = i;

  return (w+5);
}


static t_int *limiter_perform(t_int *w)
{
  t_limiter *x=(t_limiter *)w[1];
  int n = x->s_n;

  t_sample *in	= (t_sample *)w[2];
  t_sample *out= (t_sample *)w[3];

  t_limctl *v1	= (t_limctl *)(x->val1);
  t_limctl *v2	= (t_limctl *)(x->val2);
  t_cmpctl *c     = (t_cmpctl *)(x->cmp);

  /* now let's make things a little bit faster */

  /* these MUST NOT be changed by process */
  const t_float limit		= v1->limit;
  const t_float holdlong	= v1->hold_samples;
  const t_float coa_long	= v1->change_of_amplification;

  const t_float alimit		= v2->limit;
  const t_float holdshort	= v2->hold_samples;
  const t_float coa_short	= v2->change_of_amplification;

  t_float tresh  = c->treshold;
  t_float uclimit = c->uclimit;
  t_float climit_inv = c->climit_inverse;

  t_float oneminusratio = c->oneminusratio;

  /* these will be changed by process */
  t_float amp				= x->amplification;
  t_float samplesleft		= x->samples_left;
  t_float stillleft		= x->still_left;

  /* an intern variable... */
  t_float max_val;

  switch (x->mode) {
  case LIMIT0:
    while (n--) {
      max_val = *in;

      /* the MAIN routine for the 1-treshold-limiter */

      if ((max_val * amp) > limit) {
        amp = limit / max_val;
        samplesleft = holdlong;
      } else {
        if (samplesleft > 0) {
          samplesleft--;
        } else {
          if ((amp *= coa_long) > 1) {
            amp = 1;
          }
        }
      }

      *out++ = amp;
      *in++ = 0;
    }
    break;
  case LIMIT1:
    while (n--) {
      max_val = *in;
      /* the main routine 2 */

      if ((max_val * amp) > limit) {
        samplesleft = ((amp = (limit / max_val)) < alimit)?holdshort:holdlong;
        stillleft = holdlong;
      } else {
        if (samplesleft > 0) {
          samplesleft--;
          stillleft--;
        } else {
          if (amp < alimit) {
            if ((amp *= coa_short) > 1) {
              amp = 1;
            }
          } else {
            if (stillleft > 0) {
              samplesleft = stillleft;
            } else {
              if ((amp *= coa_long) > 1) {
                amp = 1;
              }
            }
          }
        }
      }
      *out++ = amp;
      *in++ = 0;
    }
    x->still_left = stillleft;
    break;
  case COMPRESS:
    while (n--) {
      max_val = *in;

      /* the MAIN routine for the compressor (very similar to the 1-treshold-limiter) */

      if (max_val * amp > tresh) {
        amp = tresh / max_val;
        samplesleft = holdlong;
      } else if (samplesleft > 0) {
        samplesleft--;
      } else if ((amp *= coa_long) > 1) {
        amp = 1;
      }

      if (amp < 1.)
        if (amp > uclimit) { /* amp is still UnCompressed  uclimit==limitIN/tresh; */
          *out++ = pow(amp, oneminusratio);
        } else {
          *out++ = amp *
                   climit_inv;  /* amp must fit for limiting : amp(new) = limit/maxval; = amp(old)*limitOUT/tresh; */
        }
      else {
        *out++ = 1.;
      }

      *in++ = 0.;
    }
    break;
  default:
    while (n--) {
      *out++ = *in++ = 0.;
    }
    break;
  }

  /* now return the goodies */
  x->amplification	= amp;
  x->samples_left		= samplesleft;

  return (w+4);
}


static void limiter_dsp(t_limiter *x, t_signal **sp)
{
  int i = 0;
  t_sample* sig_buf = (t_sample *)getbytes(sizeof(*sig_buf) * sp[0]->s_n);

  x->s_n = sp[0]->s_n;

  if (x->amplification == 0) {
    x->amplification = 0.0000001;
  }

  if (x->val2->limit >= 1) {
    x->mode = 0;
  }

  while (i < x->number_of_inlets) {
    dsp_add(oversampling_maxima, 4, x, &(x->in[i]), sp[i]->s_vec, sig_buf);
    i++;
  }

  dsp_add(limiter_perform, 3, x, sig_buf, sp[i]->s_vec);
}



/* ------------------------------------------------------------------------------------ */
/* finally do the creation - things */

static void *limiter_new(t_symbol *s, int argc, t_atom *argv)
{
  t_limiter *x = (t_limiter *)pd_new(limiter_class);
  int i = 0;

  if (argc) {
    set_bufsize(x, atom_getfloat(argv));
  } else {
    argc = 1;
    set_bufsize(x, 0);
  }

  if (argc > 64)	{
    argc=64;
  }
  if (argc == 0)	{
    argc=1;
  }

  x->number_of_inlets = argc--;

  while (argc--) {
    inlet_new(&x->x_obj, &x->x_obj.ob_pd, gensym("signal"), gensym("signal"));
  }

  outlet_new(&x->x_obj, gensym("signal"));

  x->in = (t_inbuf*)getbytes(sizeof(t_inbuf) * x->number_of_inlets);
  while (i < x->number_of_inlets) {
    int n;
    t_sample* buf = (t_sample *)getbytes(sizeof(*buf) * x->buf_size);
    x->in[i].ringbuf		= buf;
    x->in[i].buf_position	= 0;
    for (n = 0; n < x->buf_size; n++) {
      x->in[i].ringbuf[n] = 0.;
    }
    i++;
  }

  x->val1 = (t_limctl *)getbytes(sizeof(t_limctl));
  x->val2 = (t_limctl *)getbytes(sizeof(t_limctl));
  x->cmp = (t_cmpctl *)getbytes(sizeof(t_cmpctl));

  x->cmp->ratio = 1.;
  x->cmp->treshold = 1;

  set1(x, 100, 30, 139);
  set2(x, 110, 5, 14.2);

  x->amplification= 1;
  x->samples_left	= x->still_left = x->mode = 0;

  return (x);
}

static void limiter_free(t_limiter *x)
{
  int i=0;

  freebytes(x->val1, sizeof(t_limctl));
  freebytes(x->val2, sizeof(t_limctl));
  freebytes(x->cmp , sizeof(t_cmpctl));

  while (i < x->number_of_inlets)	{
    freebytes(x->in[i++].ringbuf, x->buf_size * sizeof(t_sample));
  }

  freebytes(x->in, x->number_of_inlets * sizeof(t_inbuf));
}



/* ------------------------------------------------------------------------------------ */
/* ------------------------------------------------------------------------------------ */



void limiter_tilde_setup(void)
{
  init_sinc();

  limiter_class = class_new(gensym("limiter~"), (t_newmethod)limiter_new,
                            (t_method)limiter_free,
                            sizeof(t_limiter), 0, A_GIMME, 0);

  class_addmethod(limiter_class, nullfn,					gensym("signal"), 0);
  class_addmethod(limiter_class, (t_method)limiter_dsp,	gensym("dsp"), 0);

  class_addmethod(limiter_class, (t_method)limiter_tilde_helper,
                  gensym("help"), 0);
  class_addmethod(limiter_class, (t_method)status,	gensym("print"), 0);

  class_addmethod(limiter_class, (t_method)set_mode,	gensym("mode"), A_FLOAT,
                  0);
  class_addmethod(limiter_class, (t_method)set_LIMIT,	gensym("LIMIT"),  0);
  class_addmethod(limiter_class, (t_method)set_CRACK,	gensym("CRACK"),  0);
  class_addmethod(limiter_class, (t_method)set_COMPRESS,	gensym("COMPRESS"),
                  0);


  class_addmethod(limiter_class, (t_method)set_treshold,	gensym("tresh"),
                  A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set_treshold,	gensym("treshold"),
                  A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set_ratio,	gensym("ratio"),
                  A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set1,		gensym("set"), A_FLOAT,
                  A_FLOAT, A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set2,		gensym("set2"), A_FLOAT,
                  A_FLOAT, A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set_compressor,gensym("compress"),
                  A_FLOAT, A_FLOAT, A_FLOAT, 0);

  class_addmethod(limiter_class, (t_method)set_limits,	gensym("limits"),
                  A_FLOAT, A_FLOAT, 0);
  class_addmethod(limiter_class, (t_method)set_limit,	gensym("limit"),
                  A_FLOAT, 0);
  class_addfloat (limiter_class, set_limit);

  class_addmethod(limiter_class, (t_method)reset,		gensym("reset"), 0);

  zexy_register("limiter~");
}