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Diffstat (limited to 'gst/filter/gstlpwsinc.c')
-rw-r--r-- | gst/filter/gstlpwsinc.c | 311 |
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; + } +} + |