/* -*- c-basic-offset: 2 -*- * GStreamer * Copyright (C) 1999-2001 Erik Walthinsen <omega@cse.ogi.edu> * * 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/ */ /* FIXME: * - this filter is totally unoptimized ! * - we do not destroy the allocated memory for filters and residue * - this might be improved upon with bytestream */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include <gst/gst.h> #include "gstfilter.h" #include <math.h> /* M_PI */ #include <string.h> /* memmove */ static GstElementDetails gst_lpwsinc_details = GST_ELEMENT_DETAILS ("LPWSinc", "Filter/Effect/Audio", "Low-pass Windowed sinc filter", "Thomas <thomas@apestaart.org>, " "Steven W. Smith"); enum { /* FILL ME */ LAST_SIGNAL }; enum { ARG_0, ARG_LENGTH, ARG_FREQUENCY }; #define GST_TYPE_LPWSINC \ (gst_lpwsinc_get_type()) #define GST_LPWSINC(obj) \ (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_LPWSINC,GstLPWSinc)) #define GST_LPWSINC_CLASS(klass) \ (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_ULAW,GstLPWSinc)) #define GST_IS_LPWSINC(obj) \ (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_LPWSINC)) #define GST_IS_LPWSINC_CLASS(obj) \ (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_LPWSINC)) typedef struct _GstLPWSinc GstLPWSinc; typedef struct _GstLPWSincClass GstLPWSincClass; struct _GstLPWSinc { GstElement element; GstPad *sinkpad, *srcpad; double frequency; int wing_size; /* length of a "wing" of the filter; actual length is 2 * wing_size + 1 */ gfloat *residue; /* buffer for left-over samples from previous buffer */ double *kernel; }; struct _GstLPWSincClass { GstElementClass parent_class; }; static void gst_lpwsinc_base_init (gpointer g_class); static void gst_lpwsinc_class_init (GstLPWSincClass * klass); static void gst_lpwsinc_init (GstLPWSinc * filter); static void gst_lpwsinc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void gst_lpwsinc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static void gst_lpwsinc_chain (GstPad * pad, GstData * _data); static GstPadLinkReturn gst_lpwsinc_sink_connect (GstPad * pad, const GstCaps * caps); static GstElementClass *parent_class = NULL; /*static guint gst_lpwsinc_signals[LAST_SIGNAL] = { 0 }; */ GType gst_lpwsinc_get_type (void) { static GType lpwsinc_type = 0; if (!lpwsinc_type) { static const GTypeInfo lpwsinc_info = { sizeof (GstLPWSincClass), gst_lpwsinc_base_init, NULL, (GClassInitFunc) gst_lpwsinc_class_init, NULL, NULL, sizeof (GstLPWSinc), 0, (GInstanceInitFunc) gst_lpwsinc_init, }; lpwsinc_type = g_type_register_static (GST_TYPE_ELEMENT, "GstLPWSinc", &lpwsinc_info, 0); } return lpwsinc_type; } static void gst_lpwsinc_base_init (gpointer g_class) { GstElementClass *element_class = GST_ELEMENT_CLASS (g_class); /* register src pads */ gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&gst_filter_src_template)); gst_element_class_add_pad_template (element_class, gst_static_pad_template_get (&gst_filter_sink_template)); gst_element_class_set_details (element_class, &gst_lpwsinc_details); } static void gst_lpwsinc_class_init (GstLPWSincClass * klass) { GObjectClass *gobject_class; GstElementClass *gstelement_class; gobject_class = (GObjectClass *) klass; gstelement_class = (GstElementClass *) klass; parent_class = g_type_class_ref (GST_TYPE_ELEMENT); g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_FREQUENCY, g_param_spec_double ("frequency", "Frequency", "Cut-off Frequency relative to sample rate)", 0.0, 0.5, 0, G_PARAM_READWRITE)); g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_LENGTH, g_param_spec_int ("length", "Length", "N such that the filter length = 2N + 1", 1, G_MAXINT, 1, G_PARAM_READWRITE)); gobject_class->set_property = gst_lpwsinc_set_property; gobject_class->get_property = gst_lpwsinc_get_property; } static void gst_lpwsinc_init (GstLPWSinc * filter) { filter->sinkpad = gst_pad_new_from_template (gst_static_pad_template_get (&gst_filter_sink_template), "sink"); gst_pad_set_chain_function (filter->sinkpad, gst_lpwsinc_chain); gst_pad_set_link_function (filter->sinkpad, gst_lpwsinc_sink_connect); gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad); filter->srcpad = gst_pad_new_from_template (gst_static_pad_template_get (&gst_filter_src_template), "src"); gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad); filter->wing_size = 50; filter->frequency = 0.25; filter->kernel = NULL; } static GstPadLinkReturn gst_lpwsinc_sink_connect (GstPad * pad, const GstCaps * caps) { int i = 0; double sum = 0.0; int len = 0; GstLPWSinc *filter = GST_LPWSINC (gst_pad_get_parent (pad)); GstPadLinkReturn set_retval; g_assert (GST_IS_PAD (pad)); g_assert (caps != NULL); set_retval = gst_pad_try_set_caps (filter->srcpad, caps); if (set_retval > 0) { /* connection works, so init the filter */ /* FIXME: remember to free it */ /* fill the kernel */ g_print ("DEBUG: initing filter kernel\n"); len = filter->wing_size; GST_DEBUG ("lpwsinc: initializing filter kernel of length %d", len * 2 + 1); filter->kernel = (double *) g_malloc (sizeof (double) * (2 * len + 1)); for (i = 0; i <= len * 2; ++i) { if (i == len) filter->kernel[i] = 2 * M_PI * filter->frequency; else filter->kernel[i] = sin (2 * M_PI * filter->frequency * (i - len)) / (i - len); /* windowing */ filter->kernel[i] *= (0.54 - 0.46 * cos (M_PI * i / len)); } /* normalize for unity gain at DC * FIXME: sure this is not supposed to be quadratic ? */ for (i = 0; i <= len * 2; ++i) sum += filter->kernel[i]; for (i = 0; i <= len * 2; ++i) filter->kernel[i] /= sum; /* set up the residue memory space */ filter->residue = (gfloat *) g_malloc (sizeof (gfloat) * (len * 2 + 1)); for (i = 0; i <= len * 2; ++i) filter->residue[i] = 0.0; } return set_retval; } static void gst_lpwsinc_chain (GstPad * pad, GstData * _data) { GstBuffer *buf = GST_BUFFER (_data); GstLPWSinc *filter; gfloat *src; gfloat *input; gint residue_samples; gint input_samples; gint total_samples; int i, j; filter = GST_LPWSINC (gst_pad_get_parent (pad)); /* FIXME: out of laziness, we copy the left-over bit from last buffer * together with the incoming buffer to a new buffer to make the loop * easy; this could be a lot more optimized though * to make amends we keep the incoming buffer around and write our * output samples there */ /* get a writable buffer */ buf = gst_buffer_copy_on_write (buf); src = (gfloat *) GST_BUFFER_DATA (buf); residue_samples = filter->wing_size * 2 + 1; input_samples = GST_BUFFER_SIZE (buf) / sizeof (gfloat); total_samples = residue_samples + input_samples; input = (gfloat *) g_malloc (sizeof (gfloat) * total_samples); /* copy the left-over bit */ memcpy (input, filter->residue, sizeof (gfloat) * residue_samples); /* copy the new buffer */ memcpy (&input[residue_samples], src, sizeof (gfloat) * input_samples); /* copy the tail of the current input buffer to the residue */ memcpy (filter->residue, &src[input_samples - residue_samples], sizeof (gfloat) * residue_samples); /* convolution */ /* since we copied the previous set of samples we needed before the actual * input data, we need to add the filter length to our indices for input */ for (i = 0; i < input_samples; ++i) { src[i] = 0.0; for (j = 0; j < residue_samples; ++j) src[i] += input[i - j + residue_samples] * filter->kernel[j]; } g_free (input); gst_pad_push (filter->srcpad, GST_DATA (buf)); } static void gst_lpwsinc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstLPWSinc *filter; g_return_if_fail (GST_IS_LPWSINC (object)); filter = GST_LPWSINC (object); switch (prop_id) { case ARG_LENGTH: filter->wing_size = g_value_get_int (value); break; case ARG_FREQUENCY: filter->frequency = g_value_get_double (value); break; default: break; } } static void gst_lpwsinc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstLPWSinc *filter; g_return_if_fail (GST_IS_LPWSINC (object)); filter = GST_LPWSINC (object); switch (prop_id) { case ARG_LENGTH: g_value_set_int (value, filter->wing_size); break; case ARG_FREQUENCY: g_value_set_double (value, filter->frequency); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } }