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GStreamer 0.10 Core Reference Manual | ![]() |
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GstGst — Media library supporting arbitrary formats and filter graphs. |
#include <gst/gst.h> void gst_init (int *argc, char **argv[]); gboolean gst_init_check (int *argc, char **argv[], GError **err); GOptionGroup* gst_init_get_option_group (void); void gst_deinit (void); void gst_version (guint *major, guint *minor, guint *micro, guint *nano); gchar* gst_version_string (void);
GStreamer is a framework for constructing graphs of various filters (termed elements here) that will handle streaming media. Any discreet (packetizable) media type is supported, with provisions for automatically determining source type. Formatting/framing information is provided with a powerful negotiation framework. Plugins are heavily used to provide for all elements, allowing one to construct plugins outside of the GST library, even released binary-only if license require (please don't).
GStreamer borrows heavily from both the OGI media pipeline and Microsoft's DirectShow, hopefully taking the best of both and leaving the cruft behind. Its interface is still very fluid and thus can be changed to increase the sanity/noise ratio.
The GStreamer library should be initialized with
gst_init()
before it can be used. You should pass pointers to the main argc
and argv variables so that GStreamer can process its own command line
options, as shown in the following example.
Example 1. Initializing the gstreamer library
int main (int argc, char *argv[]) { // initialize the GStreamer library gst_init (&argc, &argv); ... }
It's allowed to pass two NULL pointers to gst_init()
in case you don't want
to pass the command line args to GStreamer.
You can also use GOption to initialize your own parameters as shown in the next code fragment:
Example 2. Initializing own parameters when initializing gstreamer
static gboolean stats = FALSE;
...
int
main (int argc, char *argv[])
{
GOptionEntry options[] = {
{"tags", 't', 0, G_OPTION_ARG_NONE, &tags,
N_("Output tags (also known as metadata)"), NULL},
{NULL}
};
ctx = g_option_context_new ("gst-launch");
g_option_context_add_main_entries (ctx, options, GETTEXT_PACKAGE);
g_option_context_add_group (ctx, gst_init_get_option_group()
);
if (!g_option_context_parse (ctx, &argc, &argv, &err)) {
g_print ("Error initializing: %s\n", GST_STR_NULL (err->message));
exit (1);
}
g_option_context_free (ctx);
...
}
Use gst_version()
to query the library version at runtime or use the
GST_VERSION_* macros to find the version at compile time. Optionally
gst_version_string()
returns a printable string.
The gst_deinit()
call is used to clean up all internal resources used
by GStreamer. It is mostly used in unit tests
to check for leaks.
Last reviewed on 2005-11-23 (0.9.5)
void gst_init (int *argc, char **argv[]);
Initializes the GStreamer library, setting up internal path lists, registering built-in elements, and loading standard plugins.
This function will terminate your program if it was unable to initialize
GStreamer for some reason. If you want your program to fall back,
use gst_init_check()
instead.
WARNING: This function does not work in the same way as corresponding
functions in other glib-style libraries, such as gtk_init()
. In
particular, unknown command line options cause this function to
abort program execution.
argc : |
pointer to application's argc |
argv : |
pointer to application's argv |
gboolean gst_init_check (int *argc, char **argv[], GError **err);
Initializes the GStreamer library, setting up internal path lists, registering built-in elements, and loading standard plugins.
This function will return FALSE
if GStreamer could not be initialized
for some reason. If you want your program to fail fatally,
use gst_init()
instead.
argc : |
pointer to application's argc |
argv : |
pointer to application's argv |
err : |
pointer to a GError to which a message will be posted on error |
Returns : | TRUE if GStreamer could be initialized.
|
GOptionGroup* gst_init_get_option_group (void);
Returns a GOptionGroup with GStreamer's argument specifications. The group is set up to use standard GOption callbacks, so when using this group in combination with GOption parsing methods, all argument parsing and initialization is automated.
This function is useful if you want to integrate GStreamer with other
libraries that use GOption (see g_option_context_add_group()
).
Returns : | a pointer to GStreamer's option group. Should be dereferenced after use. |
void gst_deinit (void);
Clean up. Call only once, before exiting. After this call GStreamer should not be used anymore.
void gst_version (guint *major, guint *minor, guint *micro, guint *nano);
Gets the version number of the GStreamer library.
major : |
pointer to a guint to store the major version number |
minor : |
pointer to a guint to store the minor version number |
micro : |
pointer to a guint to store the micro version number |
nano : |
pointer to a guint to store the nano version number |
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