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

     2  * 

     3  * GStreamer

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

     5  *               2006 Dreamlab Technologies Ltd. <mathis.hofer@dreamlab.net>

     6  *               2007-2009 Sebastian Dröge <sebastian.droege@collabora.co.uk>

     7  *

     8  * This library is free software; you can redistribute it and/or

     9  * modify it under the terms of the GNU Library General Public

    10  * License as published by the Free Software Foundation; either

    11  * version 2 of the License, or (at your option) any later version.

    12  *

    13  * This library is distributed in the hope that it will be useful,

    14  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    16  * Library General Public License for more details.

    17  *

    18  * You should have received a copy of the GNU Library General Public

    19  * License along with this library; if not, write to the

    20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    21  * Boston, MA 02111-1307, USA.

    22  * 

    23  * 

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

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

    26  * chapter 16

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

    28  *

    29  */

    30 

    31 /**

    32  * SECTION:element-audiowsinclimit

    33  *

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

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

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

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

    38  *

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

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

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

    42  *

    43  * <refsect2>

    44  * <title>Example launch line</title>

    45  * |[

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

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

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

    49  * ]|

    50  * </refsect2>

    51  */

    52 

    53 #ifdef HAVE_CONFIG_H

    54 #include "config.h"

    55 #endif

    56 

    57 #include <string.h>

    58 #include <math.h>

    59 #include <gst/gst.h>

    60 #include <gst/audio/gstaudiofilter.h>

    61 #include <gst/controller/gstcontroller.h>

    62 

    63 #include "audiowsinclimit.h"

    64 

    65 #define GST_CAT_DEFAULT gst_audio_wsinclimit_debug

    66 GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);

    67 

    68 enum

    69 {

    70   PROP_0,

    71   PROP_LENGTH,

    72   PROP_FREQUENCY,

    73   PROP_MODE,

    74   PROP_WINDOW

    75 };

    76 

    77 enum

    78 {

    79   MODE_LOW_PASS = 0,

    80   MODE_HIGH_PASS

    81 };

    82 

    83 #define GST_TYPE_AUDIO_WSINC_LIMIT_MODE (gst_audio_wsinclimit_mode_get_type ())

    84 static GType

    85 gst_audio_wsinclimit_mode_get_type (void)

    86 {

    87   static GType gtype = 0;

    88 

    89   if (gtype == 0) {

    90     static const GEnumValue values[] = {

    91       {MODE_LOW_PASS, "Low pass (default)",

    92           "low-pass"},

    93       {MODE_HIGH_PASS, "High pass",

    94           "high-pass"},

    95       {0, NULL, NULL}

    96     };

    97 

    98     gtype = g_enum_register_static ("GstAudioWSincLimitMode", values);

    99   }

   100   return gtype;

   101 }

   102 

   103 enum

   104 {

   105   WINDOW_HAMMING = 0,

   106   WINDOW_BLACKMAN

   107 };

   108 

   109 #define GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW (gst_audio_wsinclimit_window_get_type ())

   110 static GType

   111 gst_audio_wsinclimit_window_get_type (void)

   112 {

   113   static GType gtype = 0;

   114 

   115   if (gtype == 0) {

   116     static const GEnumValue values[] = {

   117       {WINDOW_HAMMING, "Hamming window (default)",

   118           "hamming"},

   119       {WINDOW_BLACKMAN, "Blackman window",

   120           "blackman"},

   121       {0, NULL, NULL}

   122     };

   123 

   124     gtype = g_enum_register_static ("GstAudioWSincLimitWindow", values);

   125   }

   126   return gtype;

   127 }

   128 

   129 #define DEBUG_INIT(bla) \

   130   GST_DEBUG_CATEGORY_INIT (gst_audio_wsinclimit_debug, "audiowsinclimit", 0, \

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

   132 

   133 GST_BOILERPLATE_FULL (GstAudioWSincLimit, gst_audio_wsinclimit, GstAudioFilter,

   134     GST_TYPE_AUDIO_FX_BASE_FIR_FILTER, DEBUG_INIT);

   135 

   136 static void gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,

   137     const GValue * value, GParamSpec * pspec);

   138 static void gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,

   139     GValue * value, GParamSpec * pspec);

   140 static void gst_audio_wsinclimit_finalize (GObject * object);

   141 

   142 static gboolean gst_audio_wsinclimit_setup (GstAudioFilter * base,

   143     GstRingBufferSpec * format);

   144 

   145 /* Element class */

   146 

   147 static void

   148 gst_audio_wsinclimit_base_init (gpointer g_class)

   149 {

   150   GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

   151 

   152   gst_element_class_set_details_simple (element_class,

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

   154       "Low pass and high pass windowed sinc filter",

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

   156       "Steven W. Smith, "

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

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

   159 }

   160 

   161 static void

   162 gst_audio_wsinclimit_class_init (GstAudioWSincLimitClass * klass)

   163 {

   164   GObjectClass *gobject_class = (GObjectClass *) klass;

   165   GstAudioFilterClass *filter_class = (GstAudioFilterClass *) klass;

   166 

   167   gobject_class->set_property = gst_audio_wsinclimit_set_property;

   168   gobject_class->get_property = gst_audio_wsinclimit_get_property;

   169   gobject_class->finalize = gst_audio_wsinclimit_finalize;

   170 

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

   172    * so automatically generated UIs can use a slider */

   173   g_object_class_install_property (gobject_class, PROP_FREQUENCY,

   174       g_param_spec_float ("cutoff", "Cutoff",

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

   176           G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

   177   g_object_class_install_property (gobject_class, PROP_LENGTH,

   178       g_param_spec_int ("length", "Length",

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

   180           3, 50000, 101,

   181           G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

   182 

   183   g_object_class_install_property (gobject_class, PROP_MODE,

   184       g_param_spec_enum ("mode", "Mode",

   185           "Low pass or high pass mode", GST_TYPE_AUDIO_WSINC_LIMIT_MODE,

   186           MODE_LOW_PASS,

   187           G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

   188 

   189   g_object_class_install_property (gobject_class, PROP_WINDOW,

   190       g_param_spec_enum ("window", "Window",

   191           "Window function to use", GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW,

   192           WINDOW_HAMMING,

   193           G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));

   194 

   195   filter_class->setup = GST_DEBUG_FUNCPTR (gst_audio_wsinclimit_setup);

   196 }

   197 

   198 static void

   199 gst_audio_wsinclimit_init (GstAudioWSincLimit * self,

   200     GstAudioWSincLimitClass * g_class)

   201 {

   202   self->mode = MODE_LOW_PASS;

   203   self->window = WINDOW_HAMMING;

   204   self->kernel_length = 101;

   205   self->cutoff = 0.0;

   206 

   207   self->lock = g_mutex_new ();

   208 }

   209 

   210 static void

   211 gst_audio_wsinclimit_build_kernel (GstAudioWSincLimit * self)

   212 {

   213   gint i = 0;

   214   gdouble sum = 0.0;

   215   gint len = 0;

   216   gdouble w;

   217   gdouble *kernel = NULL;

   218 

   219   len = self->kernel_length;

   220 

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

   222     GST_DEBUG ("rate not set yet");

   223     return;

   224   }

   225 

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

   227     GST_DEBUG ("channels not set yet");

   228     return;

   229   }

   230 

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

   232   self->cutoff =

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

   234 

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

   236       "with cutoff %.2lf Hz "

   237       "for mode %s",

   238       len, self->cutoff,

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

   240 

   241   /* fill the kernel */

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

   243 

   244   kernel = g_new (gdouble, len);

   245 

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

   247     if (i == len / 2)

   248       kernel[i] = w;

   249     else

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

   251     /* windowing */

   252     if (self->window == WINDOW_HAMMING)

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

   254     else

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

   256           0.08 * cos (4 * M_PI * i / len));

   257   }

   258 

   259   /* normalize for unity gain at DC */

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

   261     sum += kernel[i];

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

   263     kernel[i] /= sum;

   264 

   265   /* convert to highpass if specified */

   266   if (self->mode == MODE_HIGH_PASS) {

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

   268       kernel[i] = -kernel[i];

   269     kernel[len / 2] += 1.0;

   270   }

   271 

   272   gst_audio_fx_base_fir_filter_set_kernel (GST_AUDIO_FX_BASE_FIR_FILTER (self),

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

   274 }

   275 

   276 /* GstAudioFilter vmethod implementations */

   277 

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

   279 static gboolean

   280 gst_audio_wsinclimit_setup (GstAudioFilter * base, GstRingBufferSpec * format)

   281 {

   282   GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (base);

   283 

   284   gst_audio_wsinclimit_build_kernel (self);

   285 

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

   287 }

   288 

   289 static void

   290 gst_audio_wsinclimit_finalize (GObject * object)

   291 {

   292   GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

   293 

   294   g_mutex_free (self->lock);

   295   self->lock = NULL;

   296 

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

   298 }

   299 

   300 static void

   301 gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,

   302     const GValue * value, GParamSpec * pspec)

   303 {

   304   GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

   305 

   306   g_return_if_fail (GST_IS_AUDIO_WSINC_LIMIT (self));

   307 

   308   switch (prop_id) {

   309     case PROP_LENGTH:{

   310       gint val;

   311 

   312       g_mutex_lock (self->lock);

   313       val = g_value_get_int (value);

   314       if (val % 2 == 0)

   315         val++;

   316 

   317       if (val != self->kernel_length) {

   318         gst_audio_fx_base_fir_filter_push_residue (GST_AUDIO_FX_BASE_FIR_FILTER

   319             (self));

   320         self->kernel_length = val;

   321         gst_audio_wsinclimit_build_kernel (self);

   322       }

   323       g_mutex_unlock (self->lock);

   324       break;

   325     }

   326     case PROP_FREQUENCY:

   327       g_mutex_lock (self->lock);

   328       self->cutoff = g_value_get_float (value);

   329       gst_audio_wsinclimit_build_kernel (self);

   330       g_mutex_unlock (self->lock);

   331       break;

   332     case PROP_MODE:

   333       g_mutex_lock (self->lock);

   334       self->mode = g_value_get_enum (value);

   335       gst_audio_wsinclimit_build_kernel (self);

   336       g_mutex_unlock (self->lock);

   337       break;

   338     case PROP_WINDOW:

   339       g_mutex_lock (self->lock);

   340       self->window = g_value_get_enum (value);

   341       gst_audio_wsinclimit_build_kernel (self);

   342       g_mutex_unlock (self->lock);

   343       break;

   344     default:

   345       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

   346       break;

   347   }

   348 }

   349 

   350 static void

   351 gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,

   352     GValue * value, GParamSpec * pspec)

   353 {

   354   GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);

   355 

   356   switch (prop_id) {

   357     case PROP_LENGTH:

   358       g_value_set_int (value, self->kernel_length);

   359       break;

   360     case PROP_FREQUENCY:

   361       g_value_set_float (value, self->cutoff);

   362       break;

   363     case PROP_MODE:

   364       g_value_set_enum (value, self->mode);

   365       break;

   366     case PROP_WINDOW:

   367       g_value_set_enum (value, self->window);

   368       break;

   369     default:

   370       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

   371       break;

   372   }

   373 }