gstreamer/gst/volume/demo.c

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/* GStreamer
*
* demo.c: sample application to change the volume of a pipeline
*
* Copyright (C) <2004> Thomas Vander Stichele <thomas at apestaart dot org>
*
* 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <math.h>
#include <gst/gst.h>
#include <gtk/gtk.h>
/* global pointer for the scale widget */
GtkWidget *elapsed;
GtkWidget *scale;
#ifndef M_LN10
#define M_LN10 (log(10.0))
#endif
static void
value_changed_callback (GtkWidget * widget, GstElement * volume)
{
gdouble value;
gdouble level;
value = gtk_range_get_value (GTK_RANGE (widget));
level = exp (value / 20.0 * M_LN10);
g_print ("Value: %f dB, level: %f\n", value, level);
g_object_set (volume, "volume", level, NULL);
}
static gboolean
idler (gpointer data)
{
GstElement *pipeline = GST_ELEMENT (data);
g_print ("+");
if (gst_bin_iterate (GST_BIN (pipeline)))
return TRUE;
gtk_main_quit ();
return FALSE;
}
static void
setup_gui (GstElement * volume)
{
GtkWidget *window;
GtkWidget *vbox;
GtkWidget *label, *hbox;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "destroy", gtk_main_quit, NULL);
vbox = gtk_vbox_new (TRUE, 0);
gtk_container_add (GTK_CONTAINER (window), vbox);
/* elapsed widget */
hbox = gtk_hbox_new (TRUE, 0);
label = gtk_label_new ("Elapsed");
elapsed = gtk_label_new ("0.000");
gtk_container_add (GTK_CONTAINER (hbox), label);
gtk_container_add (GTK_CONTAINER (hbox), elapsed);
gtk_container_add (GTK_CONTAINER (vbox), hbox);
/* volume */
hbox = gtk_hbox_new (TRUE, 0);
label = gtk_label_new ("volume");
gtk_container_add (GTK_CONTAINER (hbox), label);
scale = gtk_hscale_new_with_range (-90.0, 10.0, 0.2);
gtk_range_set_value (GTK_RANGE (scale), 0.0);
gtk_widget_set_size_request (scale, 100, -1);
gtk_container_add (GTK_CONTAINER (hbox), scale);
gtk_container_add (GTK_CONTAINER (vbox), hbox);
g_signal_connect (scale, "value-changed",
G_CALLBACK (value_changed_callback), volume);
gtk_widget_show_all (GTK_WIDGET (window));
}
int
main (int argc, char *argv[])
{
GstElement *pipeline = NULL;
GError *error = NULL;
GstElement *volume;
gst_init (&argc, &argv);
gtk_init (&argc, &argv);
pipeline = gst_parse_launchv ((const gchar **) &argv[1], &error);
if (error) {
g_print ("pipeline could not be constructed: %s\n", error->message);
g_print ("Please give a complete pipeline with a 'volume' element.\n");
g_print ("Example: sinesrc ! volume ! osssink\n");
g_error_free (error);
return 1;
}
volume = gst_bin_get_by_name (GST_BIN (pipeline), "volume0");
if (volume == NULL) {
g_print ("Please give a pipeline with a 'volume' element in it\n");
return 1;
}
/* setup GUI */
setup_gui (volume);
/* go to main loop */
gst_element_set_state (pipeline, GST_STATE_PLAYING);
g_idle_add (idler, pipeline);
gtk_main ();
return 0;
}