/* -*- c-basic-offset: 2 -*- * * GStreamer * Copyright (C) 1999-2001 Erik Walthinsen * 2006 Dreamlab Technologies Ltd. * 2007-2009 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. * * * 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. * * * Example launch line * |[ * 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 * ]| * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #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 , " "Steven W. Smith, " "Dreamlab Technologies Ltd. , " "Sebastian Dröge "); } 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; } }