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141 lines
3.8 KiB
C
141 lines
3.8 KiB
C
/* GStreamer
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* Copyright (C) 2009 Sebastian Droege <sebastian.droege@collabora.co.uk>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/* This small sample application creates a lowpass IIR filter
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* and applies it to white noise.
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* See http://www.dspguide.com/ch19/2.htm for a description
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* of the IIR filter that is used.
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*/
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/* FIXME 0.11: suppress warnings for deprecated API such as GValueArray
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* with newer GLib versions (>= 2.31.0) */
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#define GLIB_DISABLE_DEPRECATION_WARNINGS
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#include <string.h>
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#include <math.h>
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#include <gst/gst.h>
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/* Cutoff of 4000 Hz */
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#define CUTOFF (4000.0)
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static gboolean
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on_message (GstBus * bus, GstMessage * message, gpointer user_data)
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{
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GMainLoop *loop = (GMainLoop *) user_data;
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switch (GST_MESSAGE_TYPE (message)) {
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case GST_MESSAGE_ERROR:
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g_error ("Got ERROR");
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g_main_loop_quit (loop);
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break;
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case GST_MESSAGE_WARNING:
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g_warning ("Got WARNING");
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g_main_loop_quit (loop);
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break;
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case GST_MESSAGE_EOS:
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g_main_loop_quit (loop);
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break;
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default:
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break;
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}
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return TRUE;
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}
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static void
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on_rate_changed (GstElement * element, gint rate, gpointer user_data)
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{
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GValueArray *va;
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GValue v = { 0, };
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gdouble x;
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if (rate / 2.0 > CUTOFF)
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x = exp (-2.0 * G_PI * (CUTOFF / rate));
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else
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x = 0.0;
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va = g_value_array_new (1);
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g_value_init (&v, G_TYPE_DOUBLE);
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g_value_set_double (&v, 1.0 - x);
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g_value_array_append (va, &v);
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g_value_reset (&v);
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g_object_set (G_OBJECT (element), "a", va, NULL);
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g_value_array_free (va);
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va = g_value_array_new (1);
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g_value_set_double (&v, x);
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g_value_array_append (va, &v);
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g_value_reset (&v);
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g_object_set (G_OBJECT (element), "b", va, NULL);
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g_value_array_free (va);
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}
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gint
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main (gint argc, gchar * argv[])
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{
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GstElement *pipeline, *src, *filter, *conv, *sink;
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GstBus *bus;
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GMainLoop *loop;
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gst_init (NULL, NULL);
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pipeline = gst_element_factory_make ("pipeline", NULL);
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src = gst_element_factory_make ("audiotestsrc", NULL);
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g_object_set (G_OBJECT (src), "wave", 5, NULL);
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filter = gst_element_factory_make ("audioiirfilter", NULL);
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g_signal_connect (G_OBJECT (filter), "rate-changed",
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G_CALLBACK (on_rate_changed), NULL);
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conv = gst_element_factory_make ("audioconvert", NULL);
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sink = gst_element_factory_make ("autoaudiosink", NULL);
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g_return_val_if_fail (sink != NULL, -1);
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gst_bin_add_many (GST_BIN (pipeline), src, filter, conv, sink, NULL);
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if (!gst_element_link_many (src, filter, conv, sink, NULL)) {
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g_error ("Failed to link elements");
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return -2;
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}
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loop = g_main_loop_new (NULL, FALSE);
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bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
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gst_bus_add_signal_watch (bus);
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g_signal_connect (G_OBJECT (bus), "message", G_CALLBACK (on_message), loop);
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gst_object_unref (GST_OBJECT (bus));
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if (gst_element_set_state (pipeline,
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GST_STATE_PLAYING) == GST_STATE_CHANGE_FAILURE) {
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g_error ("Failed to go into PLAYING state");
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return -3;
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}
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g_main_loop_run (loop);
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gst_element_set_state (pipeline, GST_STATE_NULL);
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g_main_loop_unref (loop);
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gst_object_unref (pipeline);
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return 0;
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}
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