gstreamer/gst/equalizer/gstiirequalizer.c

/* GStreamer
 * Copyright (C) <2004> Benjamin Otte <otte@gnome.org>
 *               <2007> Stefan Kost <ensonic@users.sf.net>
 *               <2007> Sebastian Dröge <slomo@circular-chaos.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <math.h>
#include <string.h>

#include "gstiirequalizer.h"
#include "gstiirequalizernbands.h"
#include "gstiirequalizer3bands.h"
#include "gstiirequalizer10bands.h"

GST_DEBUG_CATEGORY (equalizer_debug);
#define GST_CAT_DEFAULT equalizer_debug

#define BANDS_LOCK(equ) g_mutex_lock(equ->bands_lock)
#define BANDS_UNLOCK(equ) g_mutex_unlock(equ->bands_lock)

static void gst_iir_equalizer_child_proxy_interface_init (gpointer g_iface,
    gpointer iface_data);

static void gst_iir_equalizer_finalize (GObject * object);

static gboolean gst_iir_equalizer_setup (GstAudioFilter * filter,
    const GstAudioInfo * info);
static GstFlowReturn gst_iir_equalizer_transform_ip (GstBaseTransform * btrans,
    GstBuffer * buf);

#define ALLOWED_CAPS \
    "audio/x-raw,"                                                \
    " format=(string) {"GST_AUDIO_NE(S16)","GST_AUDIO_NE(F32)","  \
                        GST_AUDIO_NE(F64)" }, "                   \
    " rate=(int)[1000,MAX],"                                      \
    " channels=(int)[1,MAX]"

#define gst_iir_equalizer_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstIirEqualizer, gst_iir_equalizer,
    GST_TYPE_AUDIO_FILTER,
    G_IMPLEMENT_INTERFACE (GST_TYPE_CHILD_PROXY,
        gst_iir_equalizer_child_proxy_interface_init));


/* child object */

enum
{
  PROP_GAIN = 1,
  PROP_FREQ,
  PROP_BANDWIDTH,
  PROP_TYPE
};

typedef enum
{
  BAND_TYPE_PEAK = 0,
  BAND_TYPE_LOW_SHELF,
  BAND_TYPE_HIGH_SHELF
} GstIirEqualizerBandType;

#define GST_TYPE_IIR_EQUALIZER_BAND_TYPE (gst_iir_equalizer_band_type_get_type ())
static GType
gst_iir_equalizer_band_type_get_type (void)
{
  static GType gtype = 0;

  if (gtype == 0) {
    static const GEnumValue values[] = {
      {BAND_TYPE_PEAK, "Peak filter (default for inner bands)", "peak"},
      {BAND_TYPE_LOW_SHELF, "Low shelf filter (default for first band)",
          "low-shelf"},
      {BAND_TYPE_HIGH_SHELF, "High shelf filter (default for last band)",
          "high-shelf"},
      {0, NULL, NULL}
    };

    gtype = g_enum_register_static ("GstIirEqualizerBandType", values);
  }
  return gtype;
}


typedef struct _GstIirEqualizerBandClass GstIirEqualizerBandClass;

#define GST_TYPE_IIR_EQUALIZER_BAND \
  (gst_iir_equalizer_band_get_type())
#define GST_IIR_EQUALIZER_BAND(obj) \
  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_IIR_EQUALIZER_BAND,GstIirEqualizerBand))
#define GST_IIR_EQUALIZER_BAND_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_IIR_EQUALIZER_BAND,GstIirEqualizerBandClass))
#define GST_IS_IIR_EQUALIZER_BAND(obj) \
  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_IIR_EQUALIZER_BAND))
#define GST_IS_IIR_EQUALIZER_BAND_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_IIR_EQUALIZER_BAND))

struct _GstIirEqualizerBand
{
  GstObject object;

  /*< private > */
  /* center frequency and gain */
  gdouble freq;
  gdouble gain;
  gdouble width;
  GstIirEqualizerBandType type;

  /* second order iir filter */
  gdouble b1, b2;               /* IIR coefficients for outputs */
  gdouble a0, a1, a2;           /* IIR coefficients for inputs */
};

struct _GstIirEqualizerBandClass
{
  GstObjectClass parent_class;
};

static GType gst_iir_equalizer_band_get_type (void);

static void
gst_iir_equalizer_band_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstIirEqualizerBand *band = GST_IIR_EQUALIZER_BAND (object);
  GstIirEqualizer *equ =
      GST_IIR_EQUALIZER (gst_object_get_parent (GST_OBJECT (band)));

  switch (prop_id) {
    case PROP_GAIN:{
      gdouble gain;

      gain = g_value_get_double (value);
      GST_DEBUG_OBJECT (band, "gain = %lf -> %lf", band->gain, gain);
      if (gain != band->gain) {
        BANDS_LOCK (equ);
        equ->need_new_coefficients = TRUE;
        band->gain = gain;
        BANDS_UNLOCK (equ);
        GST_DEBUG_OBJECT (band, "changed gain = %lf ", band->gain);
      }
      break;
    }
    case PROP_FREQ:{
      gdouble freq;

      freq = g_value_get_double (value);
      GST_DEBUG_OBJECT (band, "freq = %lf -> %lf", band->freq, freq);
      if (freq != band->freq) {
        BANDS_LOCK (equ);
        equ->need_new_coefficients = TRUE;
        band->freq = freq;
        BANDS_UNLOCK (equ);
        GST_DEBUG_OBJECT (band, "changed freq = %lf ", band->freq);
      }
      break;
    }
    case PROP_BANDWIDTH:{
      gdouble width;

      width = g_value_get_double (value);
      GST_DEBUG_OBJECT (band, "width = %lf -> %lf", band->width, width);
      if (width != band->width) {
        BANDS_LOCK (equ);
        equ->need_new_coefficients = TRUE;
        band->width = width;
        BANDS_UNLOCK (equ);
        GST_DEBUG_OBJECT (band, "changed width = %lf ", band->width);
      }
      break;
    }
    case PROP_TYPE:{
      GstIirEqualizerBandType type;

      type = g_value_get_enum (value);
      GST_DEBUG_OBJECT (band, "type = %d -> %d", band->type, type);
      if (type != band->type) {
        BANDS_LOCK (equ);
        equ->need_new_coefficients = TRUE;
        band->type = type;
        BANDS_UNLOCK (equ);
        GST_DEBUG_OBJECT (band, "changed type = %d ", band->type);
      }
      break;
    }
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }

  gst_object_unref (equ);
}

static void
gst_iir_equalizer_band_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstIirEqualizerBand *band = GST_IIR_EQUALIZER_BAND (object);

  switch (prop_id) {
    case PROP_GAIN:
      g_value_set_double (value, band->gain);
      break;
    case PROP_FREQ:
      g_value_set_double (value, band->freq);
      break;
    case PROP_BANDWIDTH:
      g_value_set_double (value, band->width);
      break;
    case PROP_TYPE:
      g_value_set_enum (value, band->type);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_iir_equalizer_band_class_init (GstIirEqualizerBandClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  gobject_class->set_property = gst_iir_equalizer_band_set_property;
  gobject_class->get_property = gst_iir_equalizer_band_get_property;

  g_object_class_install_property (gobject_class, PROP_GAIN,
      g_param_spec_double ("gain", "gain",
          "gain for the frequency band ranging from -24.0 dB to +12.0 dB",
          -24.0, 12.0, 0.0,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | GST_PARAM_CONTROLLABLE));

  g_object_class_install_property (gobject_class, PROP_FREQ,
      g_param_spec_double ("freq", "freq",
          "center frequency of the band",
          0.0, 100000.0, 0.0,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | GST_PARAM_CONTROLLABLE));

  g_object_class_install_property (gobject_class, PROP_BANDWIDTH,
      g_param_spec_double ("bandwidth", "bandwidth",
          "difference between bandedges in Hz",
          0.0, 100000.0, 1.0,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | GST_PARAM_CONTROLLABLE));

  g_object_class_install_property (gobject_class, PROP_TYPE,
      g_param_spec_enum ("type", "Type",
          "Filter type", GST_TYPE_IIR_EQUALIZER_BAND_TYPE,
          BAND_TYPE_PEAK,
          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | GST_PARAM_CONTROLLABLE));
}

static void
gst_iir_equalizer_band_init (GstIirEqualizerBand * band,
    GstIirEqualizerBandClass * klass)
{
  band->freq = 0.0;
  band->gain = 0.0;
  band->width = 1.0;
  band->type = BAND_TYPE_PEAK;
}

static GType
gst_iir_equalizer_band_get_type (void)
{
  static GType type = 0;

  if (G_UNLIKELY (!type)) {
    const GTypeInfo type_info = {
      sizeof (GstIirEqualizerBandClass),
      NULL,
      NULL,
      (GClassInitFunc) gst_iir_equalizer_band_class_init,
      NULL,
      NULL,
      sizeof (GstIirEqualizerBand),
      0,
      (GInstanceInitFunc) gst_iir_equalizer_band_init,
    };
    type =
        g_type_register_static (GST_TYPE_OBJECT, "GstIirEqualizerBand",
        &type_info, 0);
  }
  return (type);
}


/* child proxy iface */
static GstObject *
gst_iir_equalizer_child_proxy_get_child_by_index (GstChildProxy * child_proxy,
    guint index)
{
  GstIirEqualizer *equ = GST_IIR_EQUALIZER (child_proxy);
  GstObject *ret;

  BANDS_LOCK (equ);
  if (G_UNLIKELY (index >= equ->freq_band_count)) {
    BANDS_UNLOCK (equ);
    g_return_val_if_fail (index < equ->freq_band_count, NULL);
  }

  ret = gst_object_ref (equ->bands[index]);
  BANDS_UNLOCK (equ);

  GST_LOG_OBJECT (equ, "return child[%d] %" GST_PTR_FORMAT, index, ret);
  return ret;
}

static guint
gst_iir_equalizer_child_proxy_get_children_count (GstChildProxy * child_proxy)
{
  GstIirEqualizer *equ = GST_IIR_EQUALIZER (child_proxy);

  GST_LOG ("we have %d children", equ->freq_band_count);
  return equ->freq_band_count;
}

static void
gst_iir_equalizer_child_proxy_interface_init (gpointer g_iface,
    gpointer iface_data)
{
  GstChildProxyInterface *iface = g_iface;

  GST_DEBUG ("initializing iface");

  iface->get_child_by_index = gst_iir_equalizer_child_proxy_get_child_by_index;
  iface->get_children_count = gst_iir_equalizer_child_proxy_get_children_count;
}


/* equalizer implementation */

static void
gst_iir_equalizer_class_init (GstIirEqualizerClass * klass)
{
  GstAudioFilterClass *audio_filter_class = (GstAudioFilterClass *) klass;
  GstBaseTransformClass *btrans_class = (GstBaseTransformClass *) klass;
  GObjectClass *gobject_class = (GObjectClass *) klass;
  GstCaps *caps;

  gobject_class->finalize = gst_iir_equalizer_finalize;
  audio_filter_class->setup = gst_iir_equalizer_setup;
  btrans_class->transform_ip = gst_iir_equalizer_transform_ip;

  caps = gst_caps_from_string (ALLOWED_CAPS);
  gst_audio_filter_class_add_pad_templates (audio_filter_class, caps);
  gst_caps_unref (caps);
}

static void
gst_iir_equalizer_init (GstIirEqualizer * eq)
{
  eq->bands_lock = g_mutex_new ();
  eq->need_new_coefficients = TRUE;
}

static void
gst_iir_equalizer_finalize (GObject * object)
{
  GstIirEqualizer *equ = GST_IIR_EQUALIZER (object);
  gint i;

  for (i = 0; i < equ->freq_band_count; i++) {
    if (equ->bands[i])
      gst_object_unparent (GST_OBJECT (equ->bands[i]));
    equ->bands[i] = NULL;
  }
  equ->freq_band_count = 0;

  g_free (equ->bands);
  g_free (equ->history);

  g_mutex_free (equ->bands_lock);

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

/* Filter taken from
 *
 * The Equivalence of Various Methods of Computing
 * Biquad Coefficients for Audio Parametric Equalizers
 *
 * by Robert Bristow-Johnson
 *
 * http://www.aes.org/e-lib/browse.cfm?elib=6326
 * http://www.musicdsp.org/files/EQ-Coefficients.pdf
 * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
 *
 * The bandwidth method that we use here is the preferred
 * one from this article transformed from octaves to frequency
 * in Hz.
 */
static inline gdouble
arg_to_scale (gdouble arg)
{
  return (pow (10.0, arg / 40.0));
}

static gdouble
calculate_omega (gdouble freq, gint rate)
{
  gdouble omega;

  if (freq / rate >= 0.5)
    omega = G_PI;
  else if (freq <= 0.0)
    omega = 0.0;
  else
    omega = 2.0 * G_PI * (freq / rate);

  return omega;
}

static gdouble
calculate_bw (GstIirEqualizerBand * band, gint rate)
{
  gdouble bw = 0.0;

  if (band->width / rate >= 0.5) {
    /* If bandwidth == 0.5 the calculation below fails as tan(G_PI/2)
     * is undefined. So set the bandwidth to a slightly smaller value.
     */
    bw = G_PI - 0.00000001;
  } else if (band->width <= 0.0) {
    /* If bandwidth == 0 this band won't change anything so set
     * the coefficients accordingly. The coefficient calculation
     * below would create coefficients that for some reason amplify
     * the band.
     */
    band->a0 = 1.0;
    band->a1 = 0.0;
    band->a2 = 0.0;
    band->b1 = 0.0;
    band->b2 = 0.0;
  } else {
    bw = 2.0 * G_PI * (band->width / rate);
  }
  return bw;
}

static void
setup_peak_filter (GstIirEqualizer * equ, GstIirEqualizerBand * band)
{
  gint rate = GST_AUDIO_FILTER_RATE (equ);

  g_return_if_fail (rate);

  {
    gdouble gain, omega, bw;
    gdouble alpha, alpha1, alpha2, b0;

    gain = arg_to_scale (band->gain);
    omega = calculate_omega (band->freq, rate);
    bw = calculate_bw (band, rate);
    if (bw == 0.0)
      goto out;

    alpha = tan (bw / 2.0);

    alpha1 = alpha * gain;
    alpha2 = alpha / gain;

    b0 = (1.0 + alpha2);

    band->a0 = (1.0 + alpha1) / b0;
    band->a1 = (-2.0 * cos (omega)) / b0;
    band->a2 = (1.0 - alpha1) / b0;
    band->b1 = (2.0 * cos (omega)) / b0;
    band->b2 = -(1.0 - alpha2) / b0;

  out:
    GST_INFO
        ("gain = %5.1f, width= %7.2f, freq = %7.2f, a0 = %7.5g, a1 = %7.5g, a2=%7.5g b1 = %7.5g, b2 = %7.5g",
        band->gain, band->width, band->freq, band->a0, band->a1, band->a2,
        band->b1, band->b2);
  }
}

static void
setup_low_shelf_filter (GstIirEqualizer * equ, GstIirEqualizerBand * band)
{
  gint rate = GST_AUDIO_FILTER_RATE (equ);

  g_return_if_fail (rate);

  {
    gdouble gain, omega, bw;
    gdouble alpha, delta, b0;
    gdouble egp, egm;

    gain = arg_to_scale (band->gain);
    omega = calculate_omega (band->freq, rate);
    bw = calculate_bw (band, rate);
    if (bw == 0.0)
      goto out;

    egm = gain - 1.0;
    egp = gain + 1.0;
    alpha = tan (bw / 2.0);

    delta = 2.0 * sqrt (gain) * alpha;
    b0 = egp + egm * cos (omega) + delta;

    band->a0 = ((egp - egm * cos (omega) + delta) * gain) / b0;
    band->a1 = ((egm - egp * cos (omega)) * 2.0 * gain) / b0;
    band->a2 = ((egp - egm * cos (omega) - delta) * gain) / b0;
    band->b1 = ((egm + egp * cos (omega)) * 2.0) / b0;
    band->b2 = -((egp + egm * cos (omega) - delta)) / b0;


  out:
    GST_INFO
        ("gain = %5.1f, width= %7.2f, freq = %7.2f, a0 = %7.5g, a1 = %7.5g, a2=%7.5g b1 = %7.5g, b2 = %7.5g",
        band->gain, band->width, band->freq, band->a0, band->a1, band->a2,
        band->b1, band->b2);
  }
}

static void
setup_high_shelf_filter (GstIirEqualizer * equ, GstIirEqualizerBand * band)
{
  gint rate = GST_AUDIO_FILTER_RATE (equ);

  g_return_if_fail (rate);

  {
    gdouble gain, omega, bw;
    gdouble alpha, delta, b0;
    gdouble egp, egm;

    gain = arg_to_scale (band->gain);
    omega = calculate_omega (band->freq, rate);
    bw = calculate_bw (band, rate);
    if (bw == 0.0)
      goto out;

    egm = gain - 1.0;
    egp = gain + 1.0;
    alpha = tan (bw / 2.0);

    delta = 2.0 * sqrt (gain) * alpha;
    b0 = egp - egm * cos (omega) + delta;

    band->a0 = ((egp + egm * cos (omega) + delta) * gain) / b0;
    band->a1 = ((egm + egp * cos (omega)) * -2.0 * gain) / b0;
    band->a2 = ((egp + egm * cos (omega) - delta) * gain) / b0;
    band->b1 = ((egm - egp * cos (omega)) * -2.0) / b0;
    band->b2 = -((egp - egm * cos (omega) - delta)) / b0;


  out:
    GST_INFO
        ("gain = %5.1f, width= %7.2f, freq = %7.2f, a0 = %7.5g, a1 = %7.5g, a2=%7.5g b1 = %7.5g, b2 = %7.5g",
        band->gain, band->width, band->freq, band->a0, band->a1, band->a2,
        band->b1, band->b2);
  }
}

/* Must be called with bands_lock and transform lock! */
static void
set_passthrough (GstIirEqualizer * equ)
{
  gint i;
  gboolean passthrough = TRUE;

  for (i = 0; i < equ->freq_band_count; i++) {
    passthrough = passthrough && (equ->bands[i]->gain == 0.0);
  }

  gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (equ), passthrough);
  GST_DEBUG ("Passthrough mode: %d\n", passthrough);
}

/* Must be called with bands_lock and transform lock! */
static void
update_coefficients (GstIirEqualizer * equ)
{
  gint i, n = equ->freq_band_count;

  for (i = 0; i < n; i++) {
    if (equ->bands[i]->type == BAND_TYPE_PEAK)
      setup_peak_filter (equ, equ->bands[i]);
    else if (equ->bands[i]->type == BAND_TYPE_LOW_SHELF)
      setup_low_shelf_filter (equ, equ->bands[i]);
    else
      setup_high_shelf_filter (equ, equ->bands[i]);
  }

  equ->need_new_coefficients = FALSE;
}

/* Must be called with transform lock! */
static void
alloc_history (GstIirEqualizer * equ)
{
  /* free + alloc = no memcpy */
  g_free (equ->history);
  equ->history =
      g_malloc0 (equ->history_size * GST_AUDIO_FILTER_CHANNELS (equ) *
      equ->freq_band_count);
}

void
gst_iir_equalizer_compute_frequencies (GstIirEqualizer * equ, guint new_count)
{
  guint old_count, i;
  gdouble freq0, freq1, step;
  gchar name[20];

  if (equ->freq_band_count == new_count)
    return;

  BANDS_LOCK (equ);

  if (G_UNLIKELY (equ->freq_band_count == new_count)) {
    BANDS_UNLOCK (equ);
    return;
  }

  old_count = equ->freq_band_count;
  equ->freq_band_count = new_count;
  GST_DEBUG ("bands %u -> %u", old_count, new_count);

  if (old_count < new_count) {
    /* add new bands */
    equ->bands = g_realloc (equ->bands, sizeof (GstObject *) * new_count);
    for (i = old_count; i < new_count; i++) {
      equ->bands[i] = g_object_new (GST_TYPE_IIR_EQUALIZER_BAND, NULL);
      /* otherwise they get names like 'iirequalizerband5' */
      sprintf (name, "band%u", i);
      gst_object_set_name (GST_OBJECT (equ->bands[i]), name);
      GST_DEBUG ("adding band[%d]=%p", i, equ->bands[i]);

      gst_object_set_parent (GST_OBJECT (equ->bands[i]), GST_OBJECT (equ));
      gst_child_proxy_child_added (GST_OBJECT (equ),
          GST_OBJECT (equ->bands[i]));
    }
  } else {
    /* free unused bands */
    for (i = new_count; i < old_count; i++) {
      GST_DEBUG ("removing band[%d]=%p", i, equ->bands[i]);
      gst_child_proxy_child_removed (GST_OBJECT (equ),
          GST_OBJECT (equ->bands[i]));
      gst_object_unparent (GST_OBJECT (equ->bands[i]));
      equ->bands[i] = NULL;
    }
  }

  alloc_history (equ);

  /* set center frequencies and name band objects
   * FIXME: arg! we can't change the name of parented objects :(
   *   application should read band->freq to get the name
   */

  step = pow (HIGHEST_FREQ / LOWEST_FREQ, 1.0 / new_count);
  freq0 = LOWEST_FREQ;
  for (i = 0; i < new_count; i++) {
    freq1 = freq0 * step;

    if (i == 0)
      equ->bands[i]->type = BAND_TYPE_LOW_SHELF;
    else if (i == new_count - 1)
      equ->bands[i]->type = BAND_TYPE_HIGH_SHELF;
    else
      equ->bands[i]->type = BAND_TYPE_PEAK;

    equ->bands[i]->freq = freq0 + ((freq1 - freq0) / 2.0);
    equ->bands[i]->width = freq1 - freq0;
    GST_DEBUG ("band[%2d] = '%lf'", i, equ->bands[i]->freq);

    g_object_notify (G_OBJECT (equ->bands[i]), "bandwidth");
    g_object_notify (G_OBJECT (equ->bands[i]), "freq");
    g_object_notify (G_OBJECT (equ->bands[i]), "type");

    /*
       if(equ->bands[i]->freq<10000.0)
       sprintf (name,"%dHz",(gint)equ->bands[i]->freq);
       else
       sprintf (name,"%dkHz",(gint)(equ->bands[i]->freq/1000.0));
       gst_object_set_name( GST_OBJECT (equ->bands[i]), name);
       GST_DEBUG ("band[%2d] = '%s'",i,name);
     */
    freq0 = freq1;
  }

  equ->need_new_coefficients = TRUE;
  BANDS_UNLOCK (equ);
}

/* start of code that is type specific */

#define CREATE_OPTIMIZED_FUNCTIONS_INT(TYPE,BIG_TYPE,MIN_VAL,MAX_VAL)   \
typedef struct {                                                        \
  BIG_TYPE x1, x2;          /* history of input values for a filter */  \
  BIG_TYPE y1, y2;          /* history of output values for a filter */ \
} SecondOrderHistory ## TYPE;                                           \
                                                                        \
static inline BIG_TYPE                                                  \
one_step_ ## TYPE (GstIirEqualizerBand *filter,                         \
    SecondOrderHistory ## TYPE *history, BIG_TYPE input)                \
{                                                                       \
  /* calculate output */                                                \
  BIG_TYPE output = filter->a0 * input +                                \
      filter->a1 * history->x1 + filter->a2 * history->x2 +             \
      filter->b1 * history->y1 + filter->b2 * history->y2;              \
  /* update history */                                                  \
  history->y2 = history->y1;                                            \
  history->y1 = output;                                                 \
  history->x2 = history->x1;                                            \
  history->x1 = input;                                                  \
                                                                        \
  return output;                                                        \
}                                                                       \
                                                                        \
static const guint                                                      \
history_size_ ## TYPE = sizeof (SecondOrderHistory ## TYPE);            \
                                                                        \
static void                                                             \
gst_iir_equ_process_ ## TYPE (GstIirEqualizer *equ, guint8 *data,       \
guint size, guint channels)                                             \
{                                                                       \
  guint frames = size / channels / sizeof (TYPE);                       \
  guint i, c, f, nf = equ->freq_band_count;                             \
  BIG_TYPE cur;                                                         \
  GstIirEqualizerBand **filters = equ->bands;                           \
                                                                        \
  for (i = 0; i < frames; i++) {                                        \
    SecondOrderHistory ## TYPE *history = equ->history;                 \
    for (c = 0; c < channels; c++) {                                    \
      cur = *((TYPE *) data);                                           \
      for (f = 0; f < nf; f++) {                                        \
        cur = one_step_ ## TYPE (filters[f], history, cur);             \
        history++;                                                      \
      }                                                                 \
      cur = CLAMP (cur, MIN_VAL, MAX_VAL);                              \
      *((TYPE *) data) = (TYPE) floor (cur);                            \
      data += sizeof (TYPE);                                            \
    }                                                                   \
  }                                                                     \
}

#define CREATE_OPTIMIZED_FUNCTIONS(TYPE)                                \
typedef struct {                                                        \
  TYPE x1, x2;          /* history of input values for a filter */  \
  TYPE y1, y2;          /* history of output values for a filter */ \
} SecondOrderHistory ## TYPE;                                           \
                                                                        \
static inline TYPE                                                      \
one_step_ ## TYPE (GstIirEqualizerBand *filter,                         \
    SecondOrderHistory ## TYPE *history, TYPE input)                    \
{                                                                       \
  /* calculate output */                                                \
  TYPE output = filter->a0 * input + filter->a1 * history->x1 +         \
      filter->a2 * history->x2 + filter->b1 * history->y1 +             \
      filter->b2 * history->y2;                                         \
  /* update history */                                                  \
  history->y2 = history->y1;                                            \
  history->y1 = output;                                                 \
  history->x2 = history->x1;                                            \
  history->x1 = input;                                                  \
                                                                        \
  return output;                                                        \
}                                                                       \
                                                                        \
static const guint                                                      \
history_size_ ## TYPE = sizeof (SecondOrderHistory ## TYPE);            \
                                                                        \
static void                                                             \
gst_iir_equ_process_ ## TYPE (GstIirEqualizer *equ, guint8 *data,       \
guint size, guint channels)                                             \
{                                                                       \
  guint frames = size / channels / sizeof (TYPE);                       \
  guint i, c, f, nf = equ->freq_band_count;                             \
  TYPE cur;                                                             \
  GstIirEqualizerBand **filters = equ->bands;                           \
                                                                        \
  for (i = 0; i < frames; i++) {                                        \
    SecondOrderHistory ## TYPE *history = equ->history;                 \
    for (c = 0; c < channels; c++) {                                    \
      cur = *((TYPE *) data);                                           \
      for (f = 0; f < nf; f++) {                                        \
        cur = one_step_ ## TYPE (filters[f], history, cur);             \
        history++;                                                      \
      }                                                                 \
      *((TYPE *) data) = (TYPE) cur;                                    \
      data += sizeof (TYPE);                                            \
    }                                                                   \
  }                                                                     \
}

CREATE_OPTIMIZED_FUNCTIONS_INT (gint16, gfloat, -32768.0, 32767.0);
CREATE_OPTIMIZED_FUNCTIONS (gfloat);
CREATE_OPTIMIZED_FUNCTIONS (gdouble);

static GstFlowReturn
gst_iir_equalizer_transform_ip (GstBaseTransform * btrans, GstBuffer * buf)
{
  GstAudioFilter *filter = GST_AUDIO_FILTER (btrans);
  GstIirEqualizer *equ = GST_IIR_EQUALIZER (btrans);
  GstClockTime timestamp;
  guint8 *data;
  gsize size;
  gint channels = GST_AUDIO_FILTER_CHANNELS (filter);

  if (G_UNLIKELY (channels < 1 || equ->process == NULL))
    return GST_FLOW_NOT_NEGOTIATED;

  BANDS_LOCK (equ);
  if (equ->need_new_coefficients) {
    update_coefficients (equ);
    set_passthrough (equ);
  }
  BANDS_UNLOCK (equ);

  if (gst_base_transform_is_passthrough (btrans))
    return GST_FLOW_OK;

  timestamp = GST_BUFFER_TIMESTAMP (buf);
  timestamp =
      gst_segment_to_stream_time (&btrans->segment, GST_FORMAT_TIME, timestamp);

  if (GST_CLOCK_TIME_IS_VALID (timestamp))
    gst_object_sync_values (G_OBJECT (equ), timestamp);

  data = gst_buffer_map (buf, &size, NULL, GST_MAP_WRITE);
  equ->process (equ, data, size, channels);
  gst_buffer_unmap (buf, data, size);

  return GST_FLOW_OK;
}

static gboolean
gst_iir_equalizer_setup (GstAudioFilter * audio, const GstAudioInfo * info)
{
  GstIirEqualizer *equ = GST_IIR_EQUALIZER (audio);

  switch (GST_AUDIO_INFO_FORMAT (info)) {
    case GST_AUDIO_FORMAT_S16:
      equ->history_size = history_size_gint16;
      equ->process = gst_iir_equ_process_gint16;
      break;
    case GST_AUDIO_FORMAT_F32:
      equ->history_size = history_size_gfloat;
      equ->process = gst_iir_equ_process_gfloat;
      break;
    case GST_AUDIO_FORMAT_F64:
      equ->history_size = history_size_gdouble;
      equ->process = gst_iir_equ_process_gdouble;
      break;
    default:
      return FALSE;
  }

  alloc_history (equ);
  return TRUE;
}


static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (equalizer_debug, "equalizer", 0, "equalizer");

  if (!(gst_element_register (plugin, "equalizer-nbands", GST_RANK_NONE,
              GST_TYPE_IIR_EQUALIZER_NBANDS)))
    return FALSE;

  if (!(gst_element_register (plugin, "equalizer-3bands", GST_RANK_NONE,
              GST_TYPE_IIR_EQUALIZER_3BANDS)))
    return FALSE;

  if (!(gst_element_register (plugin, "equalizer-10bands", GST_RANK_NONE,
              GST_TYPE_IIR_EQUALIZER_10BANDS)))
    return FALSE;

  return TRUE;
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    "equalizer",
    "GStreamer audio equalizers",
    plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)