GStreamer
From Wikipedia, the free encyclopedia
 |
|
| Latest release | 0.10.22 / 19 January 2009 |
|---|---|
| Written in | C |
| Operating system | Cross-platform |
| Type | Multimedia framework |
| License | GNU Lesser General Public License |
| Website | gstreamer.freedesktop.org |
GStreamer is a pipeline based multimedia framework written in the C programming language with the type system based on GObject. GStreamer allows a programmer to create a variety of media-handling components, including simple audio playback, audio and video playback, recording, streaming, and editing. The pipeline design serves as a base to create many types of multimedia applications such as video editors, streaming media broadcasters, and media players.
Designed to be cross-platform, it is known to work on Linux (x86, PowerPC and ARM), Solaris (x86 and SPARC), Mac OS X, Microsoft Windows and OS/400. GStreamer has bindings for programming-languages like Python, C++, Perl, GNU Guile and Ruby. GStreamer is free software, licensed under the GNU Lesser General Public License.
Contents |
[edit] Distribution
The GNOME desktop environment, the primary user of GStreamer technology, has included GStreamer since GNOME version 2.2 and encourages GNOME and GTK+ applications to use it. Other projects also use it, such as the Chameleo media platform, Phonon and the Songbird media player.
GStreamer also operates in embedded devices like the Nokia 770, N800, Palm Pre[1] and N810 Internet Tablets running the Maemo.
[edit] History and development
Erik Walthinsen founded the GStreamer project in 1999. Many of its core design ideas came from a research project at the Oregon Graduate Institute. Wim Taymans joined the project soon thereafter and greatly expanded on many aspects of the system. Many others around the world have contributed to various degrees since then. Brock A. Frazier designed the GStreamer logo; Frazier worked for an embedded Linux company called RidgeRun, which also became the first corporate sponsor of GStreamer in the form of hiring Erik Walthinsen to develop methods for embedding GStreamer in smaller (cell phone-class) devices.
In year 2004, a company got founded by Julien Moutte, Thomas Vander Stichele and Pascal Pegaz to provide multimedia solutions in the free software market using the GStreamer framework. At that time the project was in the 0.8.x series which were not very popular mostly because of stability issue and a serious lack of features compared to competing projects like Xine, MPlayer or VLC. This company, based in Spain and named Fluendo, hired most of the core developers, including Wim Taymans who was gone from the project at that time, to bring GStreamer to a professional level and drive community adoption.
Fluendo's investment in GStreamer and GStreamer using applications, together with customers/sponsors such as Nokia and Intel, gave birth to the 0.9.x series, a major rewrite of the framework, which then became the 0.10 stable series that are widely spread today. In year 2006 GStreamer quickly acquired popularity and media players started using it such as Totem, Rhythmbox, Banshee, etc...
Meanwhile Fluendo acquired patent license agreements with commercial codecs entities such as Microsoft, MPEG LA, Via Licensing, Dolby, etc... to be able to provide legal codec solutions to other companies interested in using the GStreamer framework in their products around the globe.
As of today, GStreamer is shipped with most Linux distributions (Ubuntu, Fedora, OpenSuse, etc...) and is used by many different commercial projects.
In year 2007, some developers left Fluendo and joined various companies such as Collabora, Sun Microsystems, SongBird. Since that date GStreamer is being developed and used by many different corporations (Nokia, Motorola, Texas Instruments, Freescale, and many more) and became a very powerful cross platform multimedia framework.
freedesktop.org hosts the GStreamer project, which accordingly aims to improve interoperability and to share technology between free desktops. Since 2005, Wim Taymans maintains GStreamer.
The stable release series began with the 0.10.0 release in December 2005.[2] It has maintained API and ABI compatibility since.
[edit] Technical overview
GStreamer processes media by connecting a number of processing elements into a pipeline. Each element is provided by a plugin. Elements can be grouped into bins, which can be further aggregated, thus forming a hierarchical graph. This is an example of a filter graph.
Elements communicate by means of pads. A source pad on one element can be connected to a sink pad on another. When the pipeline is in the playing state, data buffers flow from the source pad to the sink pad. Pads negotiate the kind of data that will be sent using capabilities.
The diagram to the right could exemplify playing an MP3 file using GStreamer. The file source reads an MP3 file from a computer's hard-drive and sends it to the MP3 decoder. The decoder decodes the file data and converts it into PCM samples which then pass to the ALSA sound-driver. The ALSA sound-driver sends the PCM sound samples to the computer's speakers.
[edit] Plugins
GStreamer uses a plugin architecture which makes the most of GStreamer's functionality implemented as shared libraries. GStreamer's base functionality contains functions for registering and loading plugins and for providing the fundamentals of all classes in the form of base classes. Plugin libraries get dynamically loaded to support a wide spectrum of codecs, container formats, input/output drivers and effects.
Plugins can be installed semi-automatically when they are first needed. For that purpose distributions can register a backend that resolves feature-descriptions to package-names.
Since version 0.10 the plugins come grouped into three sets (named after the film The Good, the Bad and the Ugly),
| Plugin set name | Description |
|---|---|
| Good | This package contains the GStreamer plugins from the "good" set, a set of high quality plug-ins under the LGPL license [3] or according to Gstreamer, "contains a set of well-supported plug-ins under our preferred license".[4] |
| Bad | GStreamer Bad Plug-ins comprises a set of plug-ins not up-to-par compared to the rest. They might closely approach good-quality plugins, but they lack something: perhaps a good code review, some documentation, a set of tests, a real live maintainer, or some actual wide use.[5] |
| Ugly | This packages contains plugins from the "ugly" set, a set of good-quality plug-ins that might pose distribution problems.[6] |
Individual distributions may further sub-classify these plugins: for example Ubuntu groups the "bad" and "ugly" sets into the "Universe" or the "Multiverse" components.
[edit] References
- ^ http://developer.palm.com/webos_book/book9.html
- ^ Release Note - Announcement of first release in 0.10 stable series
- ^ gstreamer0.10-plugins-good package description (Ubuntu 6.10)
- ^ GStreamer release notes base plugins 0.10.0
- ^ gstreamer0.10-plugins-bad package description (Ubuntu 6.10)
- ^ gstreamer0.10-plugins-ugly package description (Ubuntu 6.10)
[edit] External links
|
|||||||||||||
