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---
title: Initializing GStreamer
...
# Initializing GStreamer
When writing a GStreamer application, you can simply include `gst/gst.h`
to get access to the library functions. Besides that, you will also need
to initialize the GStreamer library.
# Simple initialization
Before the GStreamer libraries can be used, `gst_init` has to be called
from the main application. This call will perform the necessary
initialization of the library as well as parse the GStreamer-specific
command line options.
A typical program \[1\] would have code to initialize GStreamer that
looks like this:
```
#include <stdio.h>
#include <gst/gst.h>
int
main (int argc,
char *argv[])
{
const gchar *nano_str;
guint major, minor, micro, nano;
gst_init (&argc, &argv);
gst_version (&major, &minor, µ, &nano);
if (nano == 1)
nano_str = "(CVS)";
else if (nano == 2)
nano_str = "(Prerelease)";
else
nano_str = "";
printf ("This program is linked against GStreamer %d.%d.%d %s\n",
major, minor, micro, nano_str);
return 0;
}
```
Use the `GST_VERSION_MAJOR`, `GST_VERSION_MINOR` and `GST_VERSION_MICRO`
macros to get the GStreamer version you are building against, or use the
function `gst_version` to get the version your application is linked
against. GStreamer currently uses a scheme where versions with the same
major and minor versions are API-/ and ABI-compatible.
It is also possible to call the `gst_init` function with two `NULL`
arguments, in which case no command line options will be parsed by
GStreamer.
# The GOption interface
You can also use a GOption table to initialize your own parameters as
shown in the next example:
```
#include <gst/gst.h>
int
main (int argc,
char *argv[])
{
gboolean silent = FALSE;
gchar *savefile = NULL;
GOptionContext *ctx;
GError *err = NULL;
GOptionEntry entries[] = {
{ "silent", 's', 0, G_OPTION_ARG_NONE, &silent,
"do not output status information", NULL },
{ "output", 'o', 0, G_OPTION_ARG_STRING, &savefile,
"save xml representation of pipeline to FILE and exit", "FILE" },
{ NULL }
};
ctx = g_option_context_new ("- Your application");
g_option_context_add_main_entries (ctx, entries, NULL);
g_option_context_add_group (ctx, gst_init_get_option_group ());
if (!g_option_context_parse (ctx, &argc, &argv, &err)) {
g_print ("Failed to initialize: %s\n", err->message);
g_clear_error (&err);
g_option_context_free (ctx);
return 1;
}
g_option_context_free (ctx);
printf ("Run me with --help to see the Application options appended.\n");
return 0;
}
```
As shown in this fragment, you can use a
[GOption](http://developer.gnome.org/glib/stable/glib-Commandline-option-parser.html)
table to define your application-specific command line options, and pass
this table to the GLib initialization function along with the option
group returned from the function `gst_init_get_option_group`. Your
application options will be parsed in addition to the standard GStreamer
options.
1. The code for this example is automatically extracted from the
documentation and built under `tests/examples/manual` in the
GStreamer tarball.
|
