3 * Copyright (C) 2009 Sebastian Dröge <sebastian.droege@collabora.co.uk>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
23 * SECTION:element-audiofirfilter
25 * audiofirfilter implements a generic audio <ulink url="http://en.wikipedia.org/wiki/Finite_impulse_response">FIR filter</ulink>. Before usage the
26 * "kernel" property has to be set to the filter kernel that should be
27 * used and the "latency" property has to be set to the latency (in samples)
28 * that is introduced by the filter kernel. Setting a latency of n samples
29 * will lead to the first n samples being dropped from the output and
30 * n samples added to the end.
32 * The filter kernel describes the impulse response of the filter. To
33 * calculate the frequency response of the filter you have to calculate
34 * the Fourier Transform of the impulse response.
36 * To change the filter kernel whenever the sampling rate changes the
37 * "rate-changed" signal can be used. This should be done for most
38 * FIR filters as they're depending on the sampling rate.
41 * <title>Example application</title>
43 * <xi:include xmlns:xi="http://www.w3.org/2003/XInclude" parse="text" href="../../../../tests/examples/audiofx/firfilter-example.c" />
55 #include <gst/audio/gstaudiofilter.h>
57 #include "audiofirfilter.h"
59 #define GST_CAT_DEFAULT gst_audio_fir_filter_debug
60 GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
75 static guint gst_audio_fir_filter_signals[LAST_SIGNAL] = { 0, };
77 #define gst_audio_fir_filter_parent_class parent_class
78 G_DEFINE_TYPE (GstAudioFIRFilter, gst_audio_fir_filter,
79 GST_TYPE_AUDIO_FX_BASE_FIR_FILTER);
81 static void gst_audio_fir_filter_set_property (GObject * object, guint prop_id,
82 const GValue * value, GParamSpec * pspec);
83 static void gst_audio_fir_filter_get_property (GObject * object, guint prop_id,
84 GValue * value, GParamSpec * pspec);
85 static void gst_audio_fir_filter_finalize (GObject * object);
87 static gboolean gst_audio_fir_filter_setup (GstAudioFilter * base,
88 const GstAudioInfo * info);
92 gst_audio_fir_filter_class_init (GstAudioFIRFilterClass * klass)
94 GObjectClass *gobject_class = (GObjectClass *) klass;
95 GstElementClass *gstelement_class = (GstElementClass *) klass;
96 GstAudioFilterClass *filter_class = (GstAudioFilterClass *) klass;
98 GST_DEBUG_CATEGORY_INIT (gst_audio_fir_filter_debug, "audiofirfilter", 0,
99 "Generic audio FIR filter plugin");
101 gobject_class->set_property = gst_audio_fir_filter_set_property;
102 gobject_class->get_property = gst_audio_fir_filter_get_property;
103 gobject_class->finalize = gst_audio_fir_filter_finalize;
105 g_object_class_install_property (gobject_class, PROP_KERNEL,
106 g_param_spec_value_array ("kernel", "Filter Kernel",
107 "Filter kernel for the FIR filter",
108 g_param_spec_double ("Element", "Filter Kernel Element",
109 "Element of the filter kernel", -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
110 G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS),
111 G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
112 g_object_class_install_property (gobject_class, PROP_LATENCY,
113 g_param_spec_uint64 ("latency", "Latecy",
114 "Filter latency in samples",
115 0, G_MAXUINT64, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
117 filter_class->setup = GST_DEBUG_FUNCPTR (gst_audio_fir_filter_setup);
120 * GstAudioFIRFilter::rate-changed:
121 * @filter: the filter on which the signal is emitted
122 * @rate: the new sampling rate
124 * Will be emitted when the sampling rate changes. The callbacks
125 * will be called from the streaming thread and processing will
126 * stop until the event is handled.
128 gst_audio_fir_filter_signals[SIGNAL_RATE_CHANGED] =
129 g_signal_new ("rate-changed", G_TYPE_FROM_CLASS (klass),
130 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstAudioFIRFilterClass, rate_changed),
131 NULL, NULL, gst_marshal_VOID__INT, G_TYPE_NONE, 1, G_TYPE_INT);
133 gst_element_class_set_details_simple (gstelement_class,
134 "Audio FIR filter", "Filter/Effect/Audio",
135 "Generic audio FIR filter with custom filter kernel",
136 "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
140 gst_audio_fir_filter_update_kernel (GstAudioFIRFilter * self, GValueArray * va)
147 g_value_array_free (self->kernel);
152 kernel = g_new (gdouble, self->kernel->n_values);
154 for (i = 0; i < self->kernel->n_values; i++) {
155 GValue *v = g_value_array_get_nth (self->kernel, i);
156 kernel[i] = g_value_get_double (v);
159 gst_audio_fx_base_fir_filter_set_kernel (GST_AUDIO_FX_BASE_FIR_FILTER (self),
160 kernel, self->kernel->n_values, self->latency);
164 gst_audio_fir_filter_init (GstAudioFIRFilter * self)
170 va = g_value_array_new (1);
172 g_value_init (&v, G_TYPE_DOUBLE);
173 g_value_set_double (&v, 1.0);
174 g_value_array_append (va, &v);
176 gst_audio_fir_filter_update_kernel (self, va);
178 self->lock = g_mutex_new ();
181 /* GstAudioFilter vmethod implementations */
183 /* get notified of caps and plug in the correct process function */
185 gst_audio_fir_filter_setup (GstAudioFilter * base, const GstAudioInfo * info)
187 GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (base);
188 gint new_rate = GST_AUDIO_INFO_RATE (info);
190 if (GST_AUDIO_FILTER_RATE (self) != new_rate) {
191 g_signal_emit (G_OBJECT (self),
192 gst_audio_fir_filter_signals[SIGNAL_RATE_CHANGED], 0, new_rate);
195 return GST_AUDIO_FILTER_CLASS (parent_class)->setup (base, info);
199 gst_audio_fir_filter_finalize (GObject * object)
201 GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object);
203 g_mutex_free (self->lock);
207 g_value_array_free (self->kernel);
210 G_OBJECT_CLASS (parent_class)->finalize (object);
214 gst_audio_fir_filter_set_property (GObject * object, guint prop_id,
215 const GValue * value, GParamSpec * pspec)
217 GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object);
219 g_return_if_fail (GST_IS_AUDIO_FIR_FILTER (self));
223 g_mutex_lock (self->lock);
224 /* update kernel already pushes residues */
225 gst_audio_fir_filter_update_kernel (self, g_value_dup_boxed (value));
226 g_mutex_unlock (self->lock);
229 g_mutex_lock (self->lock);
230 self->latency = g_value_get_uint64 (value);
231 gst_audio_fir_filter_update_kernel (self, NULL);
232 g_mutex_unlock (self->lock);
235 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
241 gst_audio_fir_filter_get_property (GObject * object, guint prop_id,
242 GValue * value, GParamSpec * pspec)
244 GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object);
248 g_value_set_boxed (value, self->kernel);
251 g_value_set_uint64 (value, self->latency);
254 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);