mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-26 02:00:33 +00:00
64 lines
2.7 KiB
Markdown
64 lines
2.7 KiB
Markdown
---
|
|
title: Interfaces
|
|
...
|
|
|
|
# Interfaces
|
|
|
|
In [Using an element as a
|
|
GObject](manual-elements.md#using-an-element-as-a-gobject), you have
|
|
learned how to use `GObject` properties as a simple way to do
|
|
interaction between applications and elements. This method suffices for
|
|
the simple'n'straight settings, but fails for anything more complicated
|
|
than a getter and setter. For the more complicated use cases, GStreamer
|
|
uses interfaces based on the GObject
|
|
[`GTypeInterface`](http://library.gnome.org/devel/gobject/stable/gtype-non-instantiable-classed.html)
|
|
type.
|
|
|
|
Most of the interfaces handled here will not contain any example code.
|
|
See the API references for details. Here, we will just describe the
|
|
scope and purpose of each interface.
|
|
|
|
## The URI interface
|
|
|
|
In all examples so far, we have only supported local files through the
|
|
“filesrc” element. GStreamer, obviously, supports many more location
|
|
sources. However, we don't want applications to need to know any
|
|
particular element implementation details, such as element names for
|
|
particular network source types and so on. Therefore, there is a URI
|
|
interface, which can be used to get the source element that supports a
|
|
particular URI type. There is no strict rule for URI naming, but in
|
|
general we follow naming conventions that others use, too. For example,
|
|
assuming you have the correct plugins installed, GStreamer supports
|
|
“file:///\<path\>/\<file\>”, “http://\<host\>/\<path\>/\<file\>”,
|
|
“mms://\<host\>/\<path\>/\<file\>”, and so on.
|
|
|
|
In order to get the source or sink element supporting a particular URI,
|
|
use `gst_element_make_from_uri ()`, with the URI type being either
|
|
`GST_URI_SRC` for a source element, or `GST_URI_SINK` for a sink
|
|
element.
|
|
|
|
You can convert filenames to and from URIs using GLib's
|
|
`g_filename_to_uri ()` and `g_uri_to_filename ()`.
|
|
|
|
## The Color Balance interface
|
|
|
|
The colorbalance interface is a way to control video-related properties
|
|
on an element, such as brightness, contrast and so on. It's sole reason
|
|
for existence is that, as far as its authors know, there's no way to
|
|
dynamically register properties using `GObject`.
|
|
|
|
The colorbalance interface is implemented by several plugins, including
|
|
xvimagesink and the Video4linux2 elements.
|
|
|
|
## The Video Overlay interface
|
|
|
|
The Video Overlay interface was created to solve the problem of
|
|
embedding video streams in an application window. The application
|
|
provides an window handle to the element implementing this interface to
|
|
draw on, and the element will then use this window handle to draw on
|
|
rather than creating a new toplevel window. This is useful to embed
|
|
video in video players.
|
|
|
|
This interface is implemented by, amongst others, the Video4linux2
|
|
elements and by ximagesink, xvimagesink and sdlvideosink.
|
|
|