meta data for this page
  •  

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision 		Previous revision
maemo:gsthello [2009/08/19 16:07]
mgynther 		maemo:gsthello [2009/08/21 11:36] (current)
kallonen
Line 1: Line 1:
-====== Gstreamer hello world ======+===== Gstreamer hello world =====
  
-This example plays a sound file given as parameter with GStreamer. It uses decodebin element so it can play any sound file that can be decoded with installed GStreamer plugins.+On this page there are two simple GStreamer examples. The first uses only one element, playbin which does all the work. The second uses multiple elements to show how elements are linked.
  
 +===== Gstreamer hello world with single element =====
 +
 +This example plays a sound file given as parameter with GStreamer. It uses playbin element so it can play any sound file that can be decoded with installed GStreamer plugins.
 +
 +
 +
 +Compiling: 
 +<code>
 +gcc -Wall $(pkg-config --cflags --libs gstreamer-0.10) filename.c -o filename
 +</code>
 +
 +<code c>
 +#include <gst/gst.h>
 +#include <glib.h>
 +#include <string.h>
 +
 +static gboolean
 +bus_call (GstBus     *bus,
 +          GstMessage *msg,
 +          gpointer    data)
 +{
 +  GMainLoop *loop = (GMainLoop *) data;
 +
 +  switch (GST_MESSAGE_TYPE (msg)) {
 +
 +    case GST_MESSAGE_EOS:
 +      g_print ("End of stream\n");
 +      g_main_loop_quit (loop);
 +      break;
 +
 +    case GST_MESSAGE_ERROR: {
 +      gchar  *debug;
 +      GError *error;
 +
 +      gst_message_parse_error (msg, &error, &debug);
 +      g_free (debug);
 +
 +      g_printerr ("Error: %s\n", error->message);
 +      g_error_free (error);
 +
 +      g_main_loop_quit (loop);
 +      break;
 +    }
 +    default:
 +      break;
 +  }
 +
 +  return TRUE;
 +}
 +
 +int
 +main (int   argc,
 +      char *argv[])
 +{
 +  GMainLoop *loop;
 +
 +  GstElement *pipeline, *bin;
 +  GstBus *bus;
 +
 + gchar path[100];
 +
 +  /* Initialisation */
 +  gst_init (&argc, &argv);
 +
 +  loop = g_main_loop_new (NULL, FALSE);
 +
 +
 +  /* Check input arguments */
 +  if (argc != 2) {
 +    g_printerr ("Usage: %s <filename>\n", argv[0]);
 +    return -1;
 +  }
 +
 +
 +  /* Create gstreamer elements */
 +  pipeline = gst_pipeline_new ("audio-player");
 +  bin   = gst_element_factory_make ("playbin",       "file-source");
 +
 +  if (!pipeline || !bin) {
 +    g_printerr ("One element could not be created. Exiting.\n");
 +    return -1;
 +  }
 +
 +  /* Set up the pipeline */
 +
 +  /* we set the input filename to the source element */
 + /* string functions can be removed. then the parameter has to contain
 +        file:/// in the beginning to play a file */
 +  strcpy(path, "file:///");
 +  strcat(path, argv[1]);
 +  g_object_set (G_OBJECT (bin), "uri", path, NULL);
 +
 +  /* we add a message handler */
 +  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
 +  gst_bus_add_watch (bus, bus_call, loop);
 +  gst_object_unref (bus);
 +
 +  /* we add all elements into the pipeline */
 +  gst_bin_add_many (GST_BIN (pipeline),
 +                    bin, NULL);
 +
 +  /* Set the pipeline to "playing" state*/
 +  g_print ("Now playing: %s\n", argv[1]);
 +  gst_element_set_state (pipeline, GST_STATE_PLAYING);
 +
 +  /* Iterate */
 +  g_print ("Running...\n");
 +  g_main_loop_run (loop);
 +
 +  /* Out of the main loop, clean up nicely */
 +  g_print ("Returned, stopping playback\n");
 +  gst_element_set_state (pipeline, GST_STATE_NULL);
 +
 +  g_print ("Deleting pipeline\n");
 +  gst_object_unref (GST_OBJECT (pipeline));
 +
 +  return 0;
 +}
 +
 +</code>
 +
 +
 +===== Gstreamer hello world with multiple elements =====
 +
 +This example plays a sound file given as parameter with GStreamer. It uses decodebin element so it can play any sound file that can be decoded with installed GStreamer plugins. Used elements are filesrc, decodebin and autoaudiosink. Elements are linked and file is played.
 +
 +
 +
 +Compiling: 
 +<code>
 +gcc -Wall $(pkg-config --cflags --libs gstreamer-0.10) filename.c -o filename
 +</code>
 <code c> <code c>
  
Line 52: Line 184:
   GstElement *decoder = (GstElement *) data;   GstElement *decoder = (GstElement *) data;
  
-  /* We can now link this pad with the vorbis-decoder sink pad */ +  g_print ("Dynamic pad created, linking \n");
-  g_print ("Dynamic pad created, linking demuxer/decoder\n");+
  
   sinkpad = gst_element_get_static_pad (decoder, "sink");   sinkpad = gst_element_get_static_pad (decoder, "sink");