1 /* -*- c-basic-offset: 2 -*-
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>
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.
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.
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.
24 * this windowed sinc filter is taken from the freely downloadable DSP book,
25 * "The Scientist and Engineer's Guide to Digital Signal Processing",
27 * available at http://www.dspguide.com/
29 * For the window functions see
30 * http://en.wikipedia.org/wiki/Window_function
34 * SECTION:element-audiowsinclimit
36 * Attenuates all frequencies above the cutoff frequency (low-pass) or all frequencies below the
37 * cutoff frequency (high-pass). The length parameter controls the rolloff, the window parameter
38 * controls rolloff and stopband attenuation. The Hamming window provides a faster rolloff but a bit
39 * worse stopband attenuation, the other way around for the Blackman window.
41 * This element has the advantage over the Chebyshev lowpass and highpass filter that it has
42 * a much better rolloff when using a larger kernel size and almost linear phase. The only
43 * disadvantage is the much slower execution time with larger kernels.
46 * <title>Example launch line</title>
48 * gst-launch audiotestsrc freq=1500 ! audioconvert ! audiowsinclimit mode=low-pass frequency=1000 length=501 ! audioconvert ! alsasink
49 * gst-launch filesrc location="melo1.ogg" ! oggdemux ! vorbisdec ! audioconvert ! audiowsinclimit mode=high-pass frequency=15000 length=501 ! audioconvert ! alsasink
50 * gst-launch audiotestsrc wave=white-noise ! audioconvert ! audiowsinclimit mode=low-pass frequency=1000 length=10001 window=blackman ! audioconvert ! alsasink
62 #include <gst/audio/gstaudiofilter.h>
63 #include <gst/controller/gstcontroller.h>
65 #include "audiowsinclimit.h"
67 #define GST_CAT_DEFAULT gst_audio_wsinclimit_debug
68 GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
85 #define GST_TYPE_AUDIO_WSINC_LIMIT_MODE (gst_audio_wsinclimit_mode_get_type ())
87 gst_audio_wsinclimit_mode_get_type (void)
89 static GType gtype = 0;
92 static const GEnumValue values[] = {
93 {MODE_LOW_PASS, "Low pass (default)",
95 {MODE_HIGH_PASS, "High pass",
100 gtype = g_enum_register_static ("GstAudioWSincLimitMode", values);
114 #define GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW (gst_audio_wsinclimit_window_get_type ())
116 gst_audio_wsinclimit_window_get_type (void)
118 static GType gtype = 0;
121 static const GEnumValue values[] = {
122 {WINDOW_HAMMING, "Hamming window (default)",
124 {WINDOW_BLACKMAN, "Blackman window",
126 {WINDOW_GAUSSIAN, "Gaussian window",
128 {WINDOW_COSINE, "Cosine window",
130 {WINDOW_HANN, "Hann window",
135 gtype = g_enum_register_static ("GstAudioWSincLimitWindow", values);
140 #define gst_audio_wsinclimit_parent_class parent_class
141 G_DEFINE_TYPE (GstAudioWSincLimit, gst_audio_wsinclimit,
142 GST_TYPE_AUDIO_FX_BASE_FIR_FILTER);
144 static void gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,
145 const GValue * value, GParamSpec * pspec);
146 static void gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,
147 GValue * value, GParamSpec * pspec);
148 static void gst_audio_wsinclimit_finalize (GObject * object);
150 static gboolean gst_audio_wsinclimit_setup (GstAudioFilter * base,
151 GstAudioInfo * info);
154 #define POW2(x) (x)*(x)
157 gst_audio_wsinclimit_class_init (GstAudioWSincLimitClass * klass)
159 GObjectClass *gobject_class = (GObjectClass *) klass;
160 GstElementClass *gstelement_class = (GstElementClass *) klass;
161 GstAudioFilterClass *filter_class = (GstAudioFilterClass *) klass;
163 GST_DEBUG_CATEGORY_INIT (gst_audio_wsinclimit_debug, "audiowsinclimit", 0,
164 "Low-pass and High-pass Windowed sinc filter plugin");
166 gobject_class->set_property = gst_audio_wsinclimit_set_property;
167 gobject_class->get_property = gst_audio_wsinclimit_get_property;
168 gobject_class->finalize = gst_audio_wsinclimit_finalize;
170 /* FIXME: Don't use the complete possible range but restrict the upper boundary
171 * so automatically generated UIs can use a slider */
172 g_object_class_install_property (gobject_class, PROP_FREQUENCY,
173 g_param_spec_float ("cutoff", "Cutoff",
174 "Cut-off Frequency (Hz)", 0.0, 100000.0, 0.0,
175 G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
176 g_object_class_install_property (gobject_class, PROP_LENGTH,
177 g_param_spec_int ("length", "Length",
178 "Filter kernel length, will be rounded to the next odd number",
180 G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
182 g_object_class_install_property (gobject_class, PROP_MODE,
183 g_param_spec_enum ("mode", "Mode",
184 "Low pass or high pass mode", GST_TYPE_AUDIO_WSINC_LIMIT_MODE,
186 G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
188 g_object_class_install_property (gobject_class, PROP_WINDOW,
189 g_param_spec_enum ("window", "Window",
190 "Window function to use", GST_TYPE_AUDIO_WSINC_LIMIT_WINDOW,
192 G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE | G_PARAM_STATIC_STRINGS));
194 gst_element_class_set_details_simple (gstelement_class,
195 "Low pass & high pass filter", "Filter/Effect/Audio",
196 "Low pass and high pass windowed sinc filter",
197 "Thomas Vander Stichele <thomas at apestaart dot org>, "
199 "Dreamlab Technologies Ltd. <mathis.hofer@dreamlab.net>, "
200 "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
202 filter_class->setup = GST_DEBUG_FUNCPTR (gst_audio_wsinclimit_setup);
206 gst_audio_wsinclimit_init (GstAudioWSincLimit * self)
208 self->mode = MODE_LOW_PASS;
209 self->window = WINDOW_HAMMING;
210 self->kernel_length = 101;
213 self->lock = g_mutex_new ();
217 gst_audio_wsinclimit_build_kernel (GstAudioWSincLimit * self)
223 gdouble *kernel = NULL;
226 len = self->kernel_length;
228 rate = GST_AUDIO_FILTER_RATE (self);
229 channels = GST_AUDIO_FILTER_CHANNELS (self);
232 GST_DEBUG ("rate not set yet");
237 GST_DEBUG ("channels not set yet");
241 /* Clamp cutoff frequency between 0 and the nyquist frequency */
242 self->cutoff = CLAMP (self->cutoff, 0.0, rate / 2);
244 GST_DEBUG ("gst_audio_wsinclimit_: initializing filter kernel of length %d "
245 "with cutoff %.2lf Hz "
248 (self->mode == MODE_LOW_PASS) ? "low-pass" : "high-pass");
250 /* fill the kernel */
251 w = 2 * G_PI * (self->cutoff / rate);
253 kernel = g_new (gdouble, len);
255 for (i = 0; i < len; ++i) {
256 if (i == (len - 1) / 2.0)
259 kernel[i] = sin (w * (i - (len - 1) / 2)) / (i - (len - 1) / 2.0);
262 switch (self->window) {
264 kernel[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / (len - 1)));
266 case WINDOW_BLACKMAN:
267 kernel[i] *= (0.42 - 0.5 * cos (2 * G_PI * i / (len - 1)) +
268 0.08 * cos (4 * G_PI * i / (len - 1)));
270 case WINDOW_GAUSSIAN:
271 kernel[i] *= exp (-0.5 * POW2 (3.0 / len * (2 * i - (len - 1))));
274 kernel[i] *= cos (G_PI * i / (len - 1) - G_PI / 2);
277 kernel[i] *= 0.5 * (1 - cos (2 * G_PI * i / (len - 1)));
282 /* normalize for unity gain at DC */
283 for (i = 0; i < len; ++i)
285 for (i = 0; i < len; ++i)
288 /* convert to highpass if specified */
289 if (self->mode == MODE_HIGH_PASS) {
290 for (i = 0; i < len; ++i)
291 kernel[i] = -kernel[i];
294 kernel[(len - 1) / 2] += 1.0;
296 kernel[len / 2 - 1] += 0.5;
297 kernel[len / 2] += 0.5;
301 gst_audio_fx_base_fir_filter_set_kernel (GST_AUDIO_FX_BASE_FIR_FILTER (self),
302 kernel, self->kernel_length, (len - 1) / 2);
305 /* GstAudioFilter vmethod implementations */
307 /* get notified of caps and plug in the correct process function */
309 gst_audio_wsinclimit_setup (GstAudioFilter * base, GstAudioInfo * info)
311 GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (base);
313 gst_audio_wsinclimit_build_kernel (self);
315 return GST_AUDIO_FILTER_CLASS (parent_class)->setup (base, info);
319 gst_audio_wsinclimit_finalize (GObject * object)
321 GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);
323 g_mutex_free (self->lock);
326 G_OBJECT_CLASS (parent_class)->finalize (object);
330 gst_audio_wsinclimit_set_property (GObject * object, guint prop_id,
331 const GValue * value, GParamSpec * pspec)
333 GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);
335 g_return_if_fail (GST_IS_AUDIO_WSINC_LIMIT (self));
341 g_mutex_lock (self->lock);
342 val = g_value_get_int (value);
346 if (val != self->kernel_length) {
347 gst_audio_fx_base_fir_filter_push_residue (GST_AUDIO_FX_BASE_FIR_FILTER
349 self->kernel_length = val;
350 gst_audio_wsinclimit_build_kernel (self);
352 g_mutex_unlock (self->lock);
356 g_mutex_lock (self->lock);
357 self->cutoff = g_value_get_float (value);
358 gst_audio_wsinclimit_build_kernel (self);
359 g_mutex_unlock (self->lock);
362 g_mutex_lock (self->lock);
363 self->mode = g_value_get_enum (value);
364 gst_audio_wsinclimit_build_kernel (self);
365 g_mutex_unlock (self->lock);
368 g_mutex_lock (self->lock);
369 self->window = g_value_get_enum (value);
370 gst_audio_wsinclimit_build_kernel (self);
371 g_mutex_unlock (self->lock);
374 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
380 gst_audio_wsinclimit_get_property (GObject * object, guint prop_id,
381 GValue * value, GParamSpec * pspec)
383 GstAudioWSincLimit *self = GST_AUDIO_WSINC_LIMIT (object);
387 g_value_set_int (value, self->kernel_length);
390 g_value_set_float (value, self->cutoff);
393 g_value_set_enum (value, self->mode);
396 g_value_set_enum (value, self->window);
399 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);