1 /* GStreamer

     2  *

     3  * volume.c: sample application to change the volume of a pipeline

     4  *

     5  * Copyright (C) <2004> Thomas Vander Stichele <thomas at apestaart dot org>

     6  *

     7  * This library is free software; you can redistribute it and/or

     8  * modify it under the terms of the GNU Library General Public

     9  * License as published by the Free Software Foundation; either

    10  * version 2 of the License, or (at your option) any later version.

    11  *

    12  * This library is distributed in the hope that it will be useful,

    13  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    15  * Library General Public License for more details.

    16  *

    17  * You should have received a copy of the GNU Library General Public

    18  * License along with this library; if not, write to the

    19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    20  * Boston, MA 02111-1307, USA.

    21  */

    22 

    23 #ifdef HAVE_CONFIG_H

    24 #include "config.h"

    25 #endif

    26 

    27 #include <math.h>

    28 

    29 #include <gst/gst.h>

    30 #include <gtk/gtk.h>

    31 

    32 /* global pointer for the scale widget */

    33 GtkWidget *elapsed;

    34 GtkWidget *scale;

    35 

    36 #ifndef M_LN10

    37 #define M_LN10 (log(10.0))

    38 #endif

    39 

    40 static void

    41 value_changed_callback (GtkWidget * widget, GstElement * volume)

    42 {

    43   gdouble value;

    44   gdouble level;

    45 

    46   value = gtk_range_get_value (GTK_RANGE (widget));

    47   level = exp (value / 20.0 * M_LN10);

    48   g_print ("Value: %f dB, level: %f\n", value, level);

    49   g_object_set (volume, "volume", level, NULL);

    50 }

    51 

    52 static void

    53 setup_gui (GstElement * volume)

    54 {

    55   GtkWidget *window;

    56   GtkWidget *vbox;

    57   GtkWidget *label, *hbox;

    58 

    59   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

    60   g_signal_connect (window, "destroy", gtk_main_quit, NULL);

    61 

    62   vbox = gtk_vbox_new (TRUE, 0);

    63   gtk_container_add (GTK_CONTAINER (window), vbox);

    64 

    65   /* elapsed widget */

    66   hbox = gtk_hbox_new (TRUE, 0);

    67   label = gtk_label_new ("Elapsed");

    68   elapsed = gtk_label_new ("0.000");

    69   gtk_container_add (GTK_CONTAINER (hbox), label);

    70   gtk_container_add (GTK_CONTAINER (hbox), elapsed);

    71   gtk_container_add (GTK_CONTAINER (vbox), hbox);

    72 

    73   /* volume */

    74   hbox = gtk_hbox_new (TRUE, 0);

    75   label = gtk_label_new ("volume");

    76   gtk_container_add (GTK_CONTAINER (hbox), label);

    77   scale = gtk_hscale_new_with_range (-90.0, 10.0, 0.2);

    78   gtk_range_set_value (GTK_RANGE (scale), 0.0);

    79   gtk_widget_set_size_request (scale, 100, -1);

    80   gtk_container_add (GTK_CONTAINER (hbox), scale);

    81   gtk_container_add (GTK_CONTAINER (vbox), hbox);

    82   g_signal_connect (scale, "value-changed",

    83       G_CALLBACK (value_changed_callback), volume);

    84 

    85   gtk_widget_show_all (GTK_WIDGET (window));

    86 }

    87 

    88 static void

    89 message_received (GstBus * bus, GstMessage * message, GstPipeline * pipeline)

    90 {

    91   const GstStructure *s;

    92 

    93   s = gst_message_get_structure (message);

    94   g_print ("message from \"%s\" (%s): ",

    95       GST_STR_NULL (GST_ELEMENT_NAME (GST_MESSAGE_SRC (message))),

    96       gst_message_type_get_name (GST_MESSAGE_TYPE (message)));

    97   if (s) {

    98     gchar *sstr;

    99 

   100     sstr = gst_structure_to_string (s);

   101     g_print ("%s\n", sstr);

   102     g_free (sstr);

   103   } else {

   104     g_print ("no message details\n");

   105   }

   106 }

   107 

   108 static void

   109 eos_message_received (GstBus * bus, GstMessage * message,

   110     GstPipeline * pipeline)

   111 {

   112   message_received (bus, message, pipeline);

   113   gtk_main_quit ();

   114 }

   115 

   116 int

   117 main (int argc, char *argv[])

   118 {

   119 

   120   GstElement *pipeline = NULL;

   121 

   122 #ifndef GST_DISABLE_PARSE

   123   GError *error = NULL;

   124 #endif

   125   GstElement *volume;

   126   GstBus *bus;

   127 

   128 #ifdef GST_DISABLE_PARSE

   129   g_print ("GStreamer was built without pipeline parsing capabilities.\n");

   130   g_print

   131       ("Please rebuild GStreamer with pipeline parsing capabilities activated to use this example.\n");

   132   return 1;

   133 #else

   134   gst_init (&argc, &argv);

   135   gtk_init (&argc, &argv);

   136 

   137   pipeline = gst_parse_launchv ((const gchar **) &argv[1], &error);

   138   if (error) {

   139     g_print ("pipeline could not be constructed: %s\n", error->message);

   140     g_print ("Please give a complete pipeline  with a 'volume' element.\n");

   141     g_print ("Example: audiotestsrc ! volume ! %s\n", DEFAULT_AUDIOSINK);

   142     g_error_free (error);

   143     return 1;

   144   }

   145 #endif

   146   volume = gst_bin_get_by_name (GST_BIN (pipeline), "volume0");

   147   if (volume == NULL) {

   148     g_print ("Please give a pipeline with a 'volume' element in it\n");

   149     return 1;

   150   }

   151 

   152   /* setup message handling */

   153   bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));

   154   gst_bus_add_signal_watch_full (bus, G_PRIORITY_HIGH);

   155   g_signal_connect (bus, "message::error", (GCallback) message_received,

   156       pipeline);

   157   g_signal_connect (bus, "message::warning", (GCallback) message_received,

   158       pipeline);

   159   g_signal_connect (bus, "message::eos", (GCallback) eos_message_received,

   160       pipeline);

   161 

   162   /* setup GUI */

   163   setup_gui (volume);

   164 

   165   /* go to main loop */

   166   gst_element_set_state (pipeline, GST_STATE_PLAYING);

   167   gtk_main ();

   168   gst_element_set_state (pipeline, GST_STATE_NULL);

   169   gst_object_unref (pipeline);

   170 

   171   return 0;

   172 }