A: No, GStreamer is a development framework for creating applications like media players, video editors, streaming media broadcasters and so on. That said, very good media players can easily be built on top of GStreamer especially when using the high-level object called playbin.
A: We like C. Aside from "personal preference", there are a number of technical reasons why C is nice in this project:
C is extremely portable.
C is fast.
It is easy to make language bindings for libraries written in C.
The GObject object system provided by GLib implements objects in C, in a portable, powerful way. This library provides for introspection and runtime dynamic typing. It is a full OO system, but without the syntactic sugar. If you want sugar, take a look at Vala.
Use of C integrates nicely with Gtk+ and GNOME. Some people like this a lot, but neither Gtk+ nor GNOME are required by GStreamer.
So, in closing, we like C. If you don't, that's fine; if you still want to help out on GStreamer, we always need more language binding people. And if not, don't bother us; we're working :-)
A: Many media player applications have chosen GStreamer for their backend. Also a couple of media format conversion tools have been written using the powers of GStreamer. With the advent of GStreamer-0.10 several media editing applications have been started.
For a list of projects, look at the application list on the GStreamer project website.
A: GStreamer aims to support every format imaginable, but that doesn't mean the developers have managed to achieve that aim yet. If a GStreamer enabled application doesn't play back your files, you can help us solve that problem by filing an enhancement request bug for that format. If you have it, please provide:
links to other players, preferably Open Source and working on Unix
links to explanations of the format.
ways to obtain mediafiles in that format to test.
A: All of GStreamer, including our own plugin code, is licensed under the GNU LGPL 2.1 license. Some of the libraries we use for some of the plugins are however under the GPL, which means that those plugins can not be used by a non-GPL-compatible application.
As part of the GStreamer source download you find a file called LICENSE_readme in gst-plugins package. That file contains information in the exact licensing terms of the libraries we use. As a general rule, GStreamer aims at using only LGPL or BSD licensed libraries if available and only use GPL or proprietary libraries where no good LGPL or BSD alternatives are available.
From GStreamer 0.4.2 on, we implemented a license field for all of the plugins, and in the future we might have the application enforce a stricter policy (much like tainting in the kernel).
A: No, GStreamer is not a soundserver. GStreamer does however have plugins supporting most of the major soundservers available today, including pulseaudio, ESD, aRTSd, Jack and others.
A: Depends. Our main target is the Unix platform. It also works on Win32 and Mac OS X, but it may still be a bit challenging to get everything up and running. That said, interest has been expressed in porting GStreamer to other platforms and the GStreamer core team will gladly accept patches to accomplish this.
A: While GStreamer is operated as an independent project, we do have a close relationship with the GNOME community. Many of our hackers consider themselves also to be members of the GNOME community. GStreamer is officialy bundled with the GNOME desktop, as lots of packages (like gnome-media, totem and rhythmbox) are using it. This does not exclude use of GStreamer by other communities at all, of course.
A: The GStreamer community wants to have as good a relationship as possible with KDE, and we hope that someday KDE decides to adopt GStreamer as their multimedia API (planned for KDE 4). There have been contacts from time to time between the GStreamer community and KDE and we do already have support for the aRTSd sound server used by KDE. Also, some of the KDE hackers have created Qt bindings of GStreamer, made a simple video player and using it in some audio players (JuK and AmaroK).
A: That doesn't really make sense. GStreamer is not a sound server, so you don't output directly to GStreamer, and it's not an intermediate API between audio data and different kinds of audio sinks. It is a fundamental design decision to use GStreamer in your app; there are no easy ways of somehow 'transfering' data from your app to GStreamer. Instead, your app would have to use or implement a number of GStreamer elements, string them together, and tell them to run. In that manner the data would all be internal to the GStreamer pipeline.
That said, it is possible to write a plugin specific to your app that can get at the audio data.