/* -*- c-basic-offset: 2 -*-

 * 

 * GStreamer

 * Copyright (C) 1999-2001 Erik Walthinsen <omega@cse.ogi.edu>

 *               2006 Dreamlab Technologies Ltd. <mathis.hofer@dreamlab.net>

 *               2007-2009 Sebastian Dröge <sebastian.droege@collabora.co.uk>

 *

 * 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.

 * 

 * 

 * this windowed sinc filter is taken from the freely downloadable DSP book,

 * "The Scientist and Engineer's Guide to Digital Signal Processing",

 * chapter 16

 * available at http://www.dspguide.com/

 *

 */

/**

 * SECTION:element-audiowsinclimit

 *

 * Attenuates all frequencies above the cutoff frequency (low-pass) or all frequencies below the

 * cutoff frequency (high-pass). The length parameter controls the rolloff, the window parameter

 * controls rolloff and stopband attenuation. The Hamming window provides a faster rolloff but a bit

 * worse stopband attenuation, the other way around for the Blackman window.

 *

 * This element has the advantage over the Chebyshev lowpass and highpass filter that it has

 * a much better rolloff when using a larger kernel size and almost linear phase. The only

 * disadvantage is the much slower execution time with larger kernels.

 *

 * <refsect2>

 * <title>Example launch line</title>

 * |[

 * gst-launch audiotestsrc freq=1500 ! audioconvert ! audiowsinclimit mode=low-pass frequency=1000 length=501 ! audioconvert ! alsasink

 * gst-launch filesrc location="melo1.ogg" ! oggdemux ! vorbisdec ! audioconvert ! audiowsinclimit mode=high-pass frequency=15000 length=501 ! audioconvert ! alsasink

 * gst-launch audiotestsrc wave=white-noise ! audioconvert ! audiowsinclimit mode=low-pass frequency=1000 length=10001 window=blackman ! audioconvert ! alsasink

 * ]|

 * </refsect2>

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <string.h>

#include <math.h>

#include <gst/gst.h>

#include <gst/audio/gstaudiofilter.h>

#include <gst/controller/gstcontroller.h>

#include "audiowsinclimit.h"

#define GST_CAT_DEFAULT gst_audio_wsinclimit_debug

GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

enum

{

  PROP_0,

  PROP_LENGTH,

  PROP_FREQUENCY,

  PROP_MODE,

  PROP_WINDOW

};

enum

{

  MODE_LOW_PASS = 0,

  MODE_HIGH_PASS

};

#define GST_TYPE_AUDIO_WSINC_LIMIT_MODE (gst_audio_wsinclimit_mode_get_type ())

static GType

gst_audio_wsinclimit_mode_get_type (void)

{

  static GType gtype = 0;

  if (gtype == 0) {

    static const GEnumValue values[] = {

      {MODE_LOW_PASS, "Low pass (default)",

          "low-pass"},

      {MODE_HIGH_PASS, "High pass",

          "high-pass"},

      {0, NULL, NULL}

    };

    gtype = g_enum_register_static ("GstAudioWSincLimitMode", values);

  }

  return gtype;

}

enum

{

  WINDOW_HAMMING = 0,

  WINDOW_BLACKMAN

};

#define GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW (gst_audio_wsinclimit_window_get_type ())

static GType

gst_audio_wsinclimit_window_get_type (void)

{

  static GType gtype = 0;

  if (gtype == 0) {

    static const GEnumValue values[] = {

      {WINDOW_HAMMING, "Hamming window (default)",

          "hamming"},

      {WINDOW_BLACKMAN, "Blackman window",

          "blackman"},

      {0, NULL, NULL}

    };

    gtype = g_enum_register_static ("GstAudioWSincLimitWindow", values);

  }

  return gtype;

}

#define DEBUG_INIT(bla) \

  GST_DEBUG_CATEGORY_INIT (gst_audio_wsinclimit_debug, "audiowsinclimit", 0, \

      "Low-pass and High-pass Windowed sinc filter plugin");

GST_BOILERPLATE_FULL (GstAudioWSincLimit, gst_audio_wsinclimit, GstAudioFilter,

    GST_TYPE_AUDIO_FX_BASE_FIR_FILTER, DEBUG_INIT);

static void gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec);

static void gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec);

static void gst_audio_wsinclimit_finalize (GObject * object);

static gboolean gst_audio_wsinclimit_setup (GstAudioFilter * base,

    GstRingBufferSpec * format);

/* Element class */

static void

gst_audio_wsinclimit_base_init (gpointer g_class)

{

  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

  gst_element_class_set_details_simple (element_class,

      "Low pass & high pass filter", "Filter/Effect/Audio",

      "Low pass and high pass windowed sinc filter",

      "Thomas Vander Stichele <thomas at apestaart dot org>, "

      "Steven W. Smith, "

      "Dreamlab Technologies Ltd. <mathis.hofer@dreamlab.net>, "

      "Sebastian Dröge <sebastian.droege@collabora.co.uk>");

}

static void

gst_audio_wsinclimit_class_init (GstAudioWSincLimitClass * klass)

{

  GObjectClass *gobject_class = (GObjectClass *) klass;

  GstAudioFilterClass *filter_class = (GstAudioFilterClass *) klass;

  gobject_class->set_property = gst_audio_wsinclimit_set_property;

  gobject_class->get_property = gst_audio_wsinclimit_get_property;

  gobject_class->finalize = gst_audio_wsinclimit_finalize;

  /* FIXME: Don't use the complete possible range but restrict the upper boundary

   * so automatically generated UIs can use a slider */

  g_object_class_install_property (gobject_class, PROP_FREQUENCY,

      g_param_spec_float ("cutoff", "Cutoff",

          "Cut-off Frequency (Hz)", 0.0, 100000.0, 0.0,

          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_LENGTH,

      g_param_spec_int ("length", "Length",

          "Filter kernel length, will be rounded to the next odd number",

          3, 50000, 101,

          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_MODE,

      g_param_spec_enum ("mode", "Mode",

          "Low pass or high pass mode", GST_TYPE_AUDIO_WSINC_LIMIT_MODE,

          MODE_LOW_PASS,

          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_WINDOW,

      g_param_spec_enum ("window", "Window",

          "Window function to use", GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW,

          WINDOW_HAMMING,

          G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

  filter_class->setup = GST_DEBUG_FUNCPTR (gst_audio_wsinclimit_setup);

}

static void

gst_audio_wsinclimit_init (GstAudioWSincLimit * self,

    GstAudioWSincLimitClass * g_class)

{

  self->mode = MODE_LOW_PASS;

  self->window = WINDOW_HAMMING;

  self->kernel_length = 101;

  self->cutoff = 0.0;

  self->lock = g_mutex_new ();

}

static void

gst_audio_wsinclimit_build_kernel (GstAudioWSincLimit * self)

{

  gint i = 0;

  gdouble sum = 0.0;

  gint len = 0;

  gdouble w;

  gdouble *kernel = NULL;

  len = self->kernel_length;

  if (GST_AUDIO_FILTER (self)->format.rate == 0) {

    GST_DEBUG ("rate not set yet");

    return;

  }

  if (GST_AUDIO_FILTER (self)->format.channels == 0) {

    GST_DEBUG ("channels not set yet");

    return;

  }

  /* Clamp cutoff frequency between 0 and the nyquist frequency */

  self->cutoff =

      CLAMP (self->cutoff, 0.0, GST_AUDIO_FILTER (self)->format.rate / 2);

  GST_DEBUG ("gst_audio_wsinclimit_: initializing filter kernel of length %d "

      "with cutoff %.2lf Hz "

      "for mode %s",

      len, self->cutoff,

      (self->mode == MODE_LOW_PASS) ? "low-pass" : "high-pass");

  /* fill the kernel */

  w = 2 * M_PI * (self->cutoff / GST_AUDIO_FILTER (self)->format.rate);

  kernel = g_new (gdouble, len);

  for (i = 0; i < len; ++i) {

    if (i == len / 2)

      kernel[i] = w;

    else

      kernel[i] = sin (w * (i - len / 2)) / (i - len / 2);

    /* windowing */

    if (self->window == WINDOW_HAMMING)

      kernel[i] *= (0.54 - 0.46 * cos (2 * M_PI * i / len));

    else

      kernel[i] *= (0.42 - 0.5 * cos (2 * M_PI * i / len) +

          0.08 * cos (4 * M_PI * i / len));

  }

  /* normalize for unity gain at DC */

  for (i = 0; i < len; ++i)

    sum += kernel[i];

  for (i = 0; i < len; ++i)

    kernel[i] /= sum;

  /* convert to highpass if specified */

  if (self->mode == MODE_HIGH_PASS) {

    for (i = 0; i < len; ++i)

      kernel[i] = -kernel[i];

    kernel[len / 2] += 1.0;

  }

  gst_audio_fx_base_fir_filter_set_kernel (GST_AUDIO_FX_BASE_FIR_FILTER (self),

      kernel, self->kernel_length, (len - 1) / 2);

}

/* GstAudioFilter vmethod implementations */

/* get notified of caps and plug in the correct process function */

static gboolean

gst_audio_wsinclimit_setup (GstAudioFilter * base, GstRingBufferSpec * format)

{

  GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (base);

  gst_audio_wsinclimit_build_kernel (self);

  return GST_AUDIO_FILTER_CLASS (parent_class)->setup (base, format);

}

static void

gst_audio_wsinclimit_finalize (GObject * object)

{

  GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

  g_mutex_free (self->lock);

  self->lock = NULL;

  G_OBJECT_CLASS (parent_class)->finalize (object);

}

static void

gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec)

{

  GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

  g_return_if_fail (GST_IS_AUDIO_WSINC_LIMIT (self));

  switch (prop_id) {

    case PROP_LENGTH:{

      gint val;

      g_mutex_lock (self->lock);

      val = g_value_get_int (value);

      if (val % 2 == 0)

        val++;

      if (val != self->kernel_length) {

        gst_audio_fx_base_fir_filter_push_residue (GST_AUDIO_FX_BASE_FIR_FILTER

            (self));

        self->kernel_length = val;

        gst_audio_wsinclimit_build_kernel (self);

      }

      g_mutex_unlock (self->lock);

      break;

    }

    case PROP_FREQUENCY:

      g_mutex_lock (self->lock);

      self->cutoff = g_value_get_float (value);

      gst_audio_wsinclimit_build_kernel (self);

      g_mutex_unlock (self->lock);

      break;

    case PROP_MODE:

      g_mutex_lock (self->lock);

      self->mode = g_value_get_enum (value);

      gst_audio_wsinclimit_build_kernel (self);

      g_mutex_unlock (self->lock);

      break;

    case PROP_WINDOW:

      g_mutex_lock (self->lock);

      self->window = g_value_get_enum (value);

      gst_audio_wsinclimit_build_kernel (self);

      g_mutex_unlock (self->lock);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}

static void

gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec)

{

  GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

  switch (prop_id) {

    case PROP_LENGTH:

      g_value_set_int (value, self->kernel_length);

      break;

    case PROP_FREQUENCY:

      g_value_set_float (value, self->cutoff);

      break;

    case PROP_MODE:

      g_value_set_enum (value, self->mode);

      break;

    case PROP_WINDOW:

      g_value_set_enum (value, self->window);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}