windowed sinc bandpass filter

Original commit message from CVS:
windowed sinc bandpass filter

1 files changed, 311 insertions, 0 deletions

diff --git a/gst/filter/gstlpwsinc.c b/gst/filter/gstlpwsinc.c
new file mode 100644
index 00000000..9a0b65e1
--- /dev/null
+++ b/gst/filter/gstlpwsinc.c
@@ -0,0 +1,311 @@
+/* -*- 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_lpwsinc_details = {
+  "LPWSinc",
+  "Filter/Audio/Effect",
+  "Low-pass 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_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_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, GstBuffer * buf);
+static GstPadConnectReturn
+       gst_lpwsinc_sink_connect 		(GstPad * pad, 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), NULL, 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_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_filter_sink_factory (), "sink");
+  gst_pad_set_chain_function (filter->sinkpad, gst_lpwsinc_chain);
+  gst_pad_set_connect_function (filter->sinkpad, gst_lpwsinc_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_lpwsinc_sink_connect (GstPad * pad, GstCaps * caps)
+{
+  int i = 0;
+  double sum = 0.0;
+  int len = 0;
+  GstLPWSinc *filter = GST_LPWSINC (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, 
+	       "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 GST_PAD_CONNECT_OK;
+  }
+
+  return GST_PAD_CONNECT_REFUSED;
+}
+
+static void
+gst_lpwsinc_chain (GstPad * pad, GstBuffer * buf)
+{
+  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 */
+
+  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_lpwsinc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec)
+{
+  GstLPWSinc *filter;
+
+  /* it's not null if we got it, but it might not be ours */
+  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;
+
+  /* it's not null if we got it, but it might not be ours */
+  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;
+  }
+} 
+