From 3641ecfbd05aa115086431808e3358ceef185a65 Mon Sep 17 00:00:00 2001 From: Thomas Vander Stichele Date: Thu, 27 Jun 2002 14:15:51 +0000 Subject: windowed sinc bandpass filter Original commit message from CVS: windowed sinc bandpass filter --- gst/filter/gstbpwsinc.c | 368 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 368 insertions(+) create mode 100644 gst/filter/gstbpwsinc.c (limited to 'gst/filter/gstbpwsinc.c') diff --git a/gst/filter/gstbpwsinc.c b/gst/filter/gstbpwsinc.c new file mode 100644 index 00000000..a6aefc6e --- /dev/null +++ b/gst/filter/gstbpwsinc.c @@ -0,0 +1,368 @@ +/* -*- c-basic-offset: 2 -*- + * GStreamer + * Copyright (C) 1999-2001 Erik Walthinsen + * + * 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 +#include "gstfilter.h" +#include /* M_PI */ +#include /* memmove */ + +GstElementDetails gst_bpwsinc_details = { + "BPWSinc", + "Filter/Audio/Effect", + "Band-Pass Windowed sinc filter", + VERSION, + "Thomas ", + "(C) 2002 Steven W. Smith", +}; + +enum { + /* FILL ME */ + LAST_SIGNAL +}; + +enum { + ARG_0, + ARG_LENGTH, + ARG_LOWER_FREQUENCY, + ARG_UPPER_FREQUENCY, +}; + +#define GST_TYPE_BPWSINC \ + (gst_bpwsinc_get_type()) +#define GST_BPWSINC(obj) \ + (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_BPWSINC,GstBPWSinc)) +#define GST_BPWSINC_CLASS(klass) \ + (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_ULAW,GstBPWSinc)) +#define GST_IS_BPWSINC(obj) \ + (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_BPWSINC)) +#define GST_IS_BPWSINC_CLASS(obj) \ + (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_BPWSINC)) + +typedef struct _GstBPWSinc GstBPWSinc; +typedef struct _GstBPWSincClass GstBPWSincClass; + +struct _GstBPWSinc +{ + GstElement element; + + GstPad *sinkpad, *srcpad; + + double frequency; + double lower_frequency, upper_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 _GstBPWSincClass +{ + GstElementClass parent_class; +}; + +static void gst_bpwsinc_class_init (GstBPWSincClass * klass); +static void gst_bpwsinc_init (GstBPWSinc * filter); + +static void gst_bpwsinc_set_property (GObject * object, guint prop_id, + const GValue * value, + GParamSpec * pspec); +static void gst_bpwsinc_get_property (GObject * object, guint prop_id, + GValue * value, GParamSpec * pspec); + +static void gst_bpwsinc_chain (GstPad * pad, GstBuffer * buf); +static GstPadConnectReturn + gst_bpwsinc_sink_connect (GstPad * pad, GstCaps * caps); + +static GstElementClass *parent_class = NULL; +/*static guint gst_bpwsinc_signals[LAST_SIGNAL] = { 0 }; */ + +GType gst_bpwsinc_get_type (void) +{ + static GType bpwsinc_type = 0; + + if (!bpwsinc_type) { + static const GTypeInfo bpwsinc_info = { + sizeof (GstBPWSincClass), NULL, NULL, + (GClassInitFunc) gst_bpwsinc_class_init, NULL, NULL, + sizeof (GstBPWSinc), 0, + (GInstanceInitFunc) gst_bpwsinc_init, + }; + + bpwsinc_type = g_type_register_static (GST_TYPE_ELEMENT, "GstBPWSinc", + &bpwsinc_info, 0); + } + return bpwsinc_type; +} + +static void +gst_bpwsinc_class_init (GstBPWSincClass * 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_LOWER_FREQUENCY, + g_param_spec_double ("lower-frequency", "Lower Frequency", + "Cut-off lower frequency (relative to sample rate)", + 0.0, 0.5, + 0, G_PARAM_READWRITE)); + g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_UPPER_FREQUENCY, + g_param_spec_double ("upper-frequency", "Upper Frequency", + "Cut-off upper 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_bpwsinc_set_property; + gobject_class->get_property = gst_bpwsinc_get_property; +} + +static void +gst_bpwsinc_init (GstBPWSinc * filter) +{ + filter->sinkpad = gst_pad_new_from_template (gst_filter_sink_factory (), "sink"); + gst_pad_set_chain_function (filter->sinkpad, gst_bpwsinc_chain); + gst_pad_set_connect_function (filter->sinkpad, gst_bpwsinc_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->lower_frequency = 0.25; + filter->upper_frequency = 0.3; + filter->kernel = NULL; +} + +static GstPadConnectReturn +gst_bpwsinc_sink_connect (GstPad * pad, GstCaps * caps) +{ + int i = 0; + double sum = 0.0; + int len = 0; + double *kernel_lp, *kernel_hp; + + GstBPWSinc *filter = GST_BPWSINC (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)) + { + len = filter->wing_size; + /* fill the lp kernel */ + GST_DEBUG (GST_CAT_PLUGIN_INFO, + "bpwsinc: initializing LP kernel of length %d with cut-off %f", + len * 2 + 1, filter->lower_frequency); + kernel_lp = (double *) g_malloc (sizeof (double) * (2 * len + 1)); + for (i = 0; i <= len * 2; ++i) + { + if (i == len) + kernel_lp[i] = 2 * M_PI * filter->lower_frequency; + else + kernel_lp[i] = sin (2 * M_PI * filter->lower_frequency * (i - len)) + / (i - len); + /* Blackman windowing */ + kernel_lp[i] *= (0.42 - 0.5 * cos (M_PI * i / len) + + 0.08 * cos (2 * M_PI * i / len)); + } + + /* normalize for unity gain at DC + * FIXME: sure this is not supposed to be quadratic ? */ + sum = 0.0; + for (i = 0; i <= len * 2; ++i) sum += kernel_lp[i]; + for (i = 0; i <= len * 2; ++i) kernel_lp[i] /= sum; + + /* fill the hp kernel */ + GST_DEBUG (GST_CAT_PLUGIN_INFO, + "bpwsinc: initializing HP kernel of length %d with cut-off %f", + len * 2 + 1, filter->upper_frequency); + kernel_hp = (double *) g_malloc (sizeof (double) * (2 * len + 1)); + for (i = 0; i <= len * 2; ++i) + { + if (i == len) + kernel_hp[i] = 2 * M_PI * filter->upper_frequency; + else + kernel_hp[i] = sin (2 * M_PI * filter->upper_frequency * (i - len)) + / (i - len); + /* Blackman windowing */ + kernel_hp[i] *= (0.42 - 0.5 * cos (M_PI * i / len) + + 0.08 * cos (2 * M_PI * i / len)); + } + + /* normalize for unity gain at DC + * FIXME: sure this is not supposed to be quadratic ? */ + sum = 0.0; + for (i = 0; i <= len * 2; ++i) sum += kernel_hp[i]; + for (i = 0; i <= len * 2; ++i) kernel_hp[i] /= sum; + + /* do spectral inversion to get a HP filter */ + for (i = 0; i <= len * 2; ++i) kernel_hp[i] = -kernel_hp[i]; + kernel_hp[len] += 1; + + /* combine the two filters */ + + filter->kernel = (double *) g_malloc (sizeof (double) * (2 * len + 1)); + + for (i = 0; i <= len * 2; ++i) + filter->kernel[i] = kernel_lp[i] + kernel_hp[i]; + + /* do spectral inversion to go from band reject to bandpass */ + for (i = 0; i <= len * 2; ++i) filter->kernel[i] = -filter->kernel[i]; + filter->kernel[len] += 1; + + /* free the helper kernels */ + g_free (kernel_lp); + g_free (kernel_hp); + + /* 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_bpwsinc_chain (GstPad * pad, GstBuffer * buf) +{ + GstBPWSinc *filter; + gfloat *src; + gfloat *input; + gint residue_samples; + gint input_samples; + gint total_samples; + int i, j; + + filter = GST_BPWSINC (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_bpwsinc_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) +{ + GstBPWSinc *filter; + + /* it's not null if we got it, but it might not be ours */ + g_return_if_fail (GST_IS_BPWSINC (object)); + + filter = GST_BPWSINC (object); + + switch (prop_id) { + case ARG_LENGTH: + filter->wing_size = g_value_get_int (value); + break; + case ARG_LOWER_FREQUENCY: + filter->lower_frequency = g_value_get_double (value); + break; + case ARG_UPPER_FREQUENCY: + filter->upper_frequency = g_value_get_double (value); + break; + default: + break; + } +} + +static void +gst_bpwsinc_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) +{ + GstBPWSinc *filter; + + /* it's not null if we got it, but it might not be ours */ + g_return_if_fail (GST_IS_BPWSINC (object)); + + filter = GST_BPWSINC (object); + + switch (prop_id) { + case ARG_LENGTH: + g_value_set_int (value, filter->wing_size); + break; + case ARG_LOWER_FREQUENCY: + g_value_set_double (value, filter->lower_frequency); + break; + case ARG_UPPER_FREQUENCY: + g_value_set_double (value, filter->upper_frequency); + break; + default: + G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); + break; + } +} + -- cgit v1.2.1