/* * GStreamer * Copyright (C) 2009 Sebastian Dröge * * 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. * */ /** * SECTION:element-audiofirfilter * * audiofirfilter implements a generic audio FIR filter. Before usage the * "kernel" property has to be set to the filter kernel that should be * used and the "latency" property has to be set to the latency (in samples) * that is introduced by the filter kernel. Setting a latency of n samples * will lead to the first n samples being dropped from the output and * n samples added to the end. * * The filter kernel describes the impulse response of the filter. To * calculate the frequency response of the filter you have to calculate * the Fourier Transform of the impulse response. * * To change the filter kernel whenever the sampling rate changes the * "rate-changed" signal can be used. This should be done for most * FIR filters as they're depending on the sampling rate. * * * Example application * |[ * * ]| * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include "audiofirfilter.h" #define GST_CAT_DEFAULT gst_audio_fir_filter_debug GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT); enum { SIGNAL_RATE_CHANGED, LAST_SIGNAL }; enum { PROP_0, PROP_KERNEL, PROP_LATENCY }; static guint gst_audio_fir_filter_signals[LAST_SIGNAL] = { 0, }; #define DEBUG_INIT(bla) \ GST_DEBUG_CATEGORY_INIT (gst_audio_fir_filter_debug, "audiofirfilter", 0, \ "Generic audio FIR filter plugin"); GST_BOILERPLATE_FULL (GstAudioFIRFilter, gst_audio_fir_filter, GstAudioFilter, GST_TYPE_AUDIO_FX_BASE_FIR_FILTER, DEBUG_INIT); static void gst_audio_fir_filter_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void gst_audio_fir_filter_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static void gst_audio_fir_filter_finalize (GObject * object); static gboolean gst_audio_fir_filter_setup (GstAudioFilter * base, GstRingBufferSpec * format); /* Element class */ static void gst_audio_fir_filter_base_init (gpointer g_class) { GstElementClass *element_class = GST_ELEMENT_CLASS (g_class); gst_element_class_set_details_simple (element_class, "Audio FIR filter", "Filter/Effect/Audio", "Generic audio FIR filter with custom filter kernel", "Sebastian Dröge "); } static void gst_audio_fir_filter_class_init (GstAudioFIRFilterClass * klass) { GObjectClass *gobject_class = (GObjectClass *) klass; GstAudioFilterClass *filter_class = (GstAudioFilterClass *) klass; gobject_class->set_property = gst_audio_fir_filter_set_property; gobject_class->get_property = gst_audio_fir_filter_get_property; gobject_class->finalize = gst_audio_fir_filter_finalize; g_object_class_install_property (gobject_class, PROP_KERNEL, g_param_spec_value_array ("kernel", "Filter Kernel", "Filter kernel for the FIR filter", g_param_spec_double ("Element", "Filter Kernel Element", "Element of the filter kernel", -G_MAXDOUBLE, G_MAXDOUBLE, 0.0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS), G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); g_object_class_install_property (gobject_class, PROP_LATENCY, g_param_spec_uint64 ("latency", "Latecy", "Filter latency in samples", 0, G_MAXUINT64, 0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)); filter_class->setup = GST_DEBUG_FUNCPTR (gst_audio_fir_filter_setup); /** * GstAudioFIRFilter::rate-changed: * @filter: the filter on which the signal is emitted * @rate: the new sampling rate * * Will be emitted when the sampling rate changes. The callbacks * will be called from the streaming thread and processing will * stop until the event is handled. */ gst_audio_fir_filter_signals[SIGNAL_RATE_CHANGED] = g_signal_new ("rate-changed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstAudioFIRFilterClass, rate_changed), NULL, NULL, gst_marshal_VOID__INT, G_TYPE_NONE, 1, G_TYPE_INT); } static void gst_audio_fir_filter_update_kernel (GstAudioFIRFilter * self, GValueArray * va) { gdouble *kernel; guint i; gst_audio_fx_base_fir_filter_push_residue (GST_AUDIO_FX_BASE_FIR_FILTER (self)); if (va) { if (self->kernel) g_value_array_free (self->kernel); self->kernel = va; } kernel = g_new (gdouble, self->kernel->n_values); for (i = 0; i < self->kernel->n_values; i++) { GValue *v = g_value_array_get_nth (self->kernel, i); kernel[i] = g_value_get_double (v); } gst_audio_fx_base_fir_filter_set_kernel (GST_AUDIO_FX_BASE_FIR_FILTER (self), kernel, self->kernel->n_values, self->latency); } static void gst_audio_fir_filter_init (GstAudioFIRFilter * self, GstAudioFIRFilterClass * g_class) { GValue v = { 0, }; GValueArray *va; self->latency = 0; va = g_value_array_new (1); g_value_init (&v, G_TYPE_DOUBLE); g_value_set_double (&v, 1.0); g_value_array_append (va, &v); g_value_unset (&v); gst_audio_fir_filter_update_kernel (self, va); self->lock = g_mutex_new (); } /* GstAudioFilter vmethod implementations */ /* get notified of caps and plug in the correct process function */ static gboolean gst_audio_fir_filter_setup (GstAudioFilter * base, GstRingBufferSpec * format) { GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (base); if (self->rate != format->rate) { g_signal_emit (G_OBJECT (self), gst_audio_fir_filter_signals[SIGNAL_RATE_CHANGED], 0, format->rate); self->rate = format->rate; } return GST_AUDIO_FILTER_CLASS (parent_class)->setup (base, format); } static void gst_audio_fir_filter_finalize (GObject * object) { GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object); g_mutex_free (self->lock); self->lock = NULL; if (self->kernel) g_value_array_free (self->kernel); self->kernel = NULL; G_OBJECT_CLASS (parent_class)->finalize (object); } static void gst_audio_fir_filter_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object); g_return_if_fail (GST_IS_AUDIO_FIR_FILTER (self)); switch (prop_id) { case PROP_KERNEL: g_mutex_lock (self->lock); gst_audio_fx_base_fir_filter_push_residue (GST_AUDIO_FX_BASE_FIR_FILTER (self)); gst_audio_fir_filter_update_kernel (self, g_value_dup_boxed (value)); g_mutex_unlock (self->lock); break; case PROP_LATENCY: g_mutex_lock (self->lock); self->latency = g_value_get_uint64 (value); gst_audio_fir_filter_update_kernel (self, NULL); g_mutex_unlock (self->lock); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void gst_audio_fir_filter_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstAudioFIRFilter *self = GST_AUDIO_FIR_FILTER (object); switch (prop_id) { case PROP_KERNEL: g_value_set_boxed (value, self->kernel); break; case PROP_LATENCY: g_value_set_uint64 (value, self->latency); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } }