Commit c903e647 authored by Thomas Vander Stichele's avatar Thomas Vander Stichele
Browse files

highly unoptimized windowed sinc filter

Original commit message from CVS:
highly unoptimized windowed sinc filter
parent 6b4bd943
......@@ -2,7 +2,7 @@ plugindir = $(libdir)/gst
plugin_LTLIBRARIES = libgstfilter.la
libgstfilter_la_SOURCES = gstfilter.c gstiir.c iir.c
libgstfilter_la_SOURCES = gstfilter.c gstiir.c iir.c gstwsinc.c
libgstfilter_la_CFLAGS = $(GST_CFLAGS)
libgstfilter_la_LIBADD =
libgstfilter_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
......
......@@ -32,6 +32,7 @@ struct _elements_entry {
static struct _elements_entry _elements[] = {
{ "iir", gst_iir_get_type, &gst_iir_details, NULL },
{ "wsinc", gst_wsinc_get_type, &gst_wsinc_details, NULL },
{ NULL, 0 },
};
......
......@@ -31,4 +31,7 @@ extern GstElementDetails gst_iir_details;
extern GstPadTemplate *gst_filter_sink_factory ();
extern GstPadTemplate *gst_filter_src_factory ();
GType gst_wsinc_get_type (void);
extern GstElementDetails gst_wsinc_details;
#endif /* __GST_FILTER_H__ */
......@@ -136,7 +136,7 @@ gst_iir_class_init (GstIIRClass * klass)
g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_STAGES,
g_param_spec_int ("stages", "Stages", "Number of filter stages",
1, G_MAXINT,
0, G_PARAM_READWRITE));
1, G_PARAM_READWRITE));
gobject_class->set_property = gst_iir_set_property;
gobject_class->get_property = gst_iir_get_property;
......
/* -*- 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
*/
#include <gst/gst.h>
#include "gstfilter.h"
#include <math.h> /* M_PI */
#include <string.h> /* memmove */
GstElementDetails gst_wsinc_details = {
"WSinc",
"Filter/Audio/Effect",
"Windowed sinc filter",
VERSION,
"Thomas <thomas@apestaart.org>",
"(C) 2002 Steven W. Smith",
};
enum {
/* FILL ME */
LAST_SIGNAL
};
enum {
ARG_0,
ARG_LENGTH,
ARG_FREQUENCY,
};
#define GST_TYPE_WSINC \
(gst_wsinc_get_type())
#define GST_WSINC(obj) \
(G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_WSINC,GstWSinc))
#define GST_WSINC_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_ULAW,GstWSinc))
#define GST_IS_WSINC(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_WSINC))
#define GST_IS_WSINC_CLASS(obj) \
(G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_WSINC))
typedef struct _GstWSinc GstWSinc;
typedef struct _GstWSincClass GstWSincClass;
struct _GstWSinc
{
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 _GstWSincClass
{
GstElementClass parent_class;
};
static void gst_wsinc_class_init (GstWSincClass * klass);
static void gst_wsinc_init (GstWSinc * filter);
static void gst_wsinc_set_property (GObject * object, guint prop_id,
const GValue * value,
GParamSpec * pspec);
static void gst_wsinc_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec);
static void gst_wsinc_chain (GstPad * pad, GstBuffer * buf);
static GstPadConnectReturn
gst_wsinc_sink_connect (GstPad * pad, GstCaps * caps);
static GstElementClass *parent_class = NULL;
/*static guint gst_wsinc_signals[LAST_SIGNAL] = { 0 }; */
GType gst_wsinc_get_type (void)
{
static GType wsinc_type = 0;
if (!wsinc_type) {
static const GTypeInfo wsinc_info = {
sizeof (GstWSincClass), NULL, NULL,
(GClassInitFunc) gst_wsinc_class_init, NULL, NULL,
sizeof (GstWSinc), 0,
(GInstanceInitFunc) gst_wsinc_init,
};
wsinc_type = g_type_register_static (GST_TYPE_ELEMENT, "GstWSinc",
&wsinc_info, 0);
}
return wsinc_type;
}
static void
gst_wsinc_class_init (GstWSincClass * 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_wsinc_set_property;
gobject_class->get_property = gst_wsinc_get_property;
}
static void
gst_wsinc_init (GstWSinc * filter)
{
filter->sinkpad = gst_pad_new_from_template (gst_filter_sink_factory (), "sink");
gst_pad_set_chain_function (filter->sinkpad, gst_wsinc_chain);
gst_pad_set_connect_function (filter->sinkpad, gst_wsinc_sink_connect);
gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);
filter->srcpad = gst_pad_new_from_template (gst_filter_src_factory (), "src");
gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);
filter->wing_size = 50;
filter->frequency = 0.25;
filter->kernel = NULL;
}
static GstPadConnectReturn
gst_wsinc_sink_connect (GstPad * pad, GstCaps * caps)
{
int i = 0;
double sum = 0.0;
int len = 0;
GstWSinc *filter = GST_WSINC (gst_pad_get_parent (pad));
g_assert (GST_IS_PAD (pad));
g_assert (caps != NULL);
if (!GST_CAPS_IS_FIXED (caps))
return GST_PAD_CONNECT_DELAYED;
if (gst_pad_try_set_caps (filter->srcpad, caps))
{
/* 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 (GST_CAT_PLUGIN_INFO,
"wsinc: 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 GST_PAD_CONNECT_OK;
}
return GST_PAD_CONNECT_REFUSED;
}
static void
gst_wsinc_chain (GstPad * pad, GstBuffer * buf)
{
GstWSinc *filter;
gfloat *src;
gfloat *input;
gint residue_samples;
gint input_samples;
gint total_samples;
int i, j;
filter = GST_WSINC (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 */
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, buf);
}
static void
gst_wsinc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec)
{
GstWSinc *filter;
/* it's not null if we got it, but it might not be ours */
g_return_if_fail (GST_IS_WSINC (object));
filter = GST_WSINC (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_wsinc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec)
{
GstWSinc *filter;
/* it's not null if we got it, but it might not be ours */
g_return_if_fail (GST_IS_WSINC (object));
filter = GST_WSINC (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;
}
}
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