Add a simple example of inclusion

0.7.9.3 is needed, but it's pushed on pip so it shouldn't
be too complicated.

Need the C extension as well, README updated to reflect
that.

This allowed noticing and fixing two errors in the
link_to_multiplexer snippet, as clang complained,
check the differences between the previous version
and the new one :)
This commit is contained in:
Mathieu Duponchelle 2016-06-04 18:19:38 +02:00
parent 2b89969d95
commit e256a61106
6 changed files with 128 additions and 128 deletions

3
README
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@ -24,6 +24,9 @@ for *stable* automatic formatting.
* Follow [hotdoc's installation guide](https://people.collabora.com/~meh/hotdoc_hotdoc/html/installing.html),
preferably in a virtualenv.
* We *experimentally* use the hotdoc C extension to include functions by
name, follow the steps outlined [here](https://github.com/hotdoc/hotdoc_c_extension)
* Optionally install the `hotdoc_search_extension`:
```

82
examples/bus_example.c Normal file
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@ -0,0 +1,82 @@
#include <gst/gst.h>
static GMainLoop *loop;
static gboolean
my_bus_callback (GstBus *bus,
GstMessage *message,
gpointer data)
{
g_print ("Got %s message\n", GST_MESSAGE_TYPE_NAME (message));
switch (GST_MESSAGE_TYPE (message)) {
case GST_MESSAGE_ERROR: {
GError *err;
gchar *debug;
gst_message_parse_error (message, &err, &debug);
g_print ("Error: %s\n", err->message);
g_error_free (err);
g_free (debug);
g_main_loop_quit (loop);
break;
}
case GST_MESSAGE_EOS:
/* end-of-stream */
g_main_loop_quit (loop);
break;
default:
/* unhandled message */
break;
}
/* we want to be notified again the next time there is a message
* on the bus, so returning TRUE (FALSE means we want to stop watching
* for messages on the bus and our callback should not be called again)
*/
return TRUE;
}
gint
main (gint argc,
gchar *argv[])
{
GstElement *pipeline;
GstBus *bus;
guint bus_watch_id;
/* init */
gst_init (&argc, &argv);
/* create pipeline, add handler */
pipeline = gst_pipeline_new ("my_pipeline");
/* adds a watch for new message on our pipeline's message bus to
* the default GLib main context, which is the main context that our
* GLib main loop is attached to below
*/
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
bus_watch_id = gst_bus_add_watch (bus, my_bus_callback, NULL);
gst_object_unref (bus);
/* [...] */
/* create a mainloop that runs/iterates the default GLib main context
* (context NULL), in other words: makes the context check if anything
* it watches for has happened. When a message has been posted on the
* bus, the default main context will automatically call our
* my_bus_callback() function to notify us of that message.
* The main loop will be run until someone calls g_main_loop_quit()
*/
loop = g_main_loop_new (NULL, FALSE);
g_main_loop_run (loop);
/* clean up */
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
g_source_remove (bus_watch_id);
g_main_loop_unref (loop);
return 0;
}

38
examples/snippets.c Normal file
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@ -0,0 +1,38 @@
#include <gst/gst.h>
static void
link_to_multiplexer (GstPad *tolink_pad,
GstElement *mux)
{
GstPad *pad;
gchar *srcname, *sinkname;
srcname = gst_pad_get_name (tolink_pad);
pad = gst_element_get_compatible_pad (mux, tolink_pad, NULL);
gst_pad_link (tolink_pad, pad);
sinkname = gst_pad_get_name (pad);
gst_object_unref (GST_OBJECT (pad));
g_print ("A new pad %s was created and linked to %s\n", sinkname, srcname);
g_free (sinkname);
g_free (srcname);
}
static void
some_function (GstElement *tee)
{
GstPad * pad;
gchar *name;
pad = gst_element_get_request_pad (tee, "src%d");
name = gst_pad_get_name (pad);
g_print ("A new pad %s was created\n", name);
g_free (name);
/* here, you would link the pad */
/* [..] */
/* and, after doing that, free our reference */
gst_object_unref (GST_OBJECT (pad));
}

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@ -5,5 +5,6 @@
"output": "built_doc",
"project_name": "gstdotcom",
"sitemap": "sitemap.txt",
"extra_assets": ["attachments", "images"]
"extra_assets": ["attachments", "images"],
"pkg_config_packages": ["gstreamer-1.0"]
}

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@ -39,94 +39,8 @@ There are two different ways to use a bus:
- Check for messages on the bus yourself. This can be done using
`gst_bus_peek ()` and/or `gst_bus_poll ()`.
<!-- end list -->
```
#include <gst/gst.h>
static GMainLoop *loop;
static gboolean
my_bus_callback (GstBus *bus,
GstMessage *message,
gpointer data)
{
g_print ("Got %s message\n", GST_MESSAGE_TYPE_NAME (message));
switch (GST_MESSAGE_TYPE (message)) {
case GST_MESSAGE_ERROR: {
GError *err;
gchar *debug;
gst_message_parse_error (message, &err, &debug);
g_print ("Error: %s\n", err->message);
g_error_free (err);
g_free (debug);
g_main_loop_quit (loop);
break;
}
case GST_MESSAGE_EOS:
/* end-of-stream */
g_main_loop_quit (loop);
break;
default:
/* unhandled message */
break;
}
/* we want to be notified again the next time there is a message
* on the bus, so returning TRUE (FALSE means we want to stop watching
* for messages on the bus and our callback should not be called again)
*/
return TRUE;
}
gint
main (gint argc,
gchar *argv[])
{
GstElement *pipeline;
GstBus *bus;
guint bus_watch_id;
/* init */
gst_init (&argc, &argv);
/* create pipeline, add handler */
pipeline = gst_pipeline_new ("my_pipeline");
/* adds a watch for new message on our pipeline's message bus to
* the default GLib main context, which is the main context that our
* GLib main loop is attached to below
*/
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
bus_watch_id = gst_bus_add_watch (bus, my_bus_callback, NULL);
gst_object_unref (bus);
[..]
/* create a mainloop that runs/iterates the default GLib main context
* (context NULL), in other words: makes the context check if anything
* it watches for has happened. When a message has been posted on the
* bus, the default main context will automatically call our
* my_bus_callback() function to notify us of that message.
* The main loop will be run until someone calls g_main_loop_quit()
*/
loop = g_main_loop_new (NULL, FALSE);
g_main_loop_run (loop);
/* clean up */
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
g_source_remove (bus_watch_id);
g_main_loop_unref (loop);
return 0;
}
```
{{ examples/bus_example.c }}
It is important to know that the handler will be called in the thread
context of the mainloop. This means that the interaction between the

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@ -123,26 +123,7 @@ the stream, it can simply request a new output pad from the tee element.
The following piece of code shows how you can request a new output pad
from a “tee” element:
```
static void
some_function (GstElement *tee)
{
GstPad * pad;
gchar *name;
pad = gst_element_get_request_pad (tee, "src%d");
name = gst_pad_get_name (pad);
g_print ("A new pad %s was created\n", name);
g_free (name);
/* here, you would link the pad */
[..]
/* and, after doing that, free our reference */
gst_object_unref (GST_OBJECT (pad));
}
```
{{ examples/snippets.c#some_function }}
The `gst_element_get_request_pad ()` method can be used to get a pad
from the element based on the name of the pad template. It is also
@ -153,26 +134,7 @@ element and you need to request a pad that is compatible. The method
pad, as shown in the next example. It will request a compatible pad from
an Ogg multiplexer from any input.
```
static void
link_to_multiplexer (GstPad *tolink_pad,
GstElement *mux)
{
GstPad *pad;
gchar *srcname, *sinkname;
srcname = gst_pad_get_name (tolink_pad);
pad = gst_element_get_compatible_pad (mux, tolink_pad);
gst_pad_link (tolinkpad, pad);
sinkname = gst_pad_get_name (pad);
gst_object_unref (GST_OBJECT (pad));
g_print ("A new pad %s was created and linked to %s\n", sinkname, srcname);
g_free (sinkname);
g_free (srcname);
}
```
{{ examples/snippets.c#link_to_multiplexer }}
# Capabilities of a pad