A bin is a container element. You can add elements to a bin. Since a bin is an element itself, a bin can be handled in the same way as any other element. Therefore, the whole previous chapter () applies to bins as well. Bins allow you to combine a group of linked elements into one logical element. You do not deal with the individual elements anymore but with just one element, the bin. We will see that this is extremely powerful when you are going to construct complex pipelines since it allows you to break up the pipeline in smaller chunks. The bin will also manage the elements contained in it. It will figure out how the data will flow in the bin and generate an optimal plan for that data flow. Plan generation is one of the most complicated procedures in &GStreamer;. You will learn more about this process, called scheduling, in .

There is one specialized type of bin available to the &GStreamer; programmer: A pipeline: a generic container that allows scheduling of the containing elements. The toplevel bin has to be a pipeline, every application thus needs at least one of these. Pipelines will automatically run themselves in a background thread when started. Bins are created in the same way that other elements are created, i.e. using an element factory. There are also convenience functions available (gst_bin_new () and gst_pipeline_new ()). To add elements to a bin or remove elements from a bin, you can use gst_bin_add () and gst_bin_remove (). Note that the bin that you add an element to will take ownership of that element. If you destroy the bin, the element will be dereferenced with it. If you remove an element from a bin, it will be dereferenced automatically. #include <gst/gst.h> int main (int argc, char *argv[]) { GstElement *bin, *pipeline, *source, *sink; /* init */ gst_init (&argc, &argv); /* create */ pipeline = gst_pipeline_new ("my_pipeline"); bin = gst_pipeline_new ("my_bin"); source = gst_element_factory_make ("fakesrc", "source"); sink = gst_element_factory_make ("fakesink", "sink"); /* set up pipeline */ gst_bin_add_many (GST_BIN (bin), source, sink, NULL); gst_bin_add (GST_BIN (pipeline), bin); gst_element_link (source, sink); [..] } There are various functions to lookup elements in a bin. You can also get a list of all elements that a bin contains using the function gst_bin_get_list (). See the API references of GstBin for details. The application programmer can create custom bins packed with elements to perform a specific task. This allows you, for example, to write an Ogg/Vorbis decoder with just the following lines of code: int main (int argc char *argv[]) { GstElement *player; /* init */ gst_init (&argc, &argv); /* create player */ player = gst_element_factory_make ("oggvorbisplayer", "player"); /* set the source audio file */ g_object_set (player, "location", "helloworld.ogg", NULL); /* start playback */ gst_element_set_state (GST_ELEMENT (player), GST_STATE_PLAYING); [..] } Custom bins can be created with a plugin or an XML description. You will find more information about creating custom bin in the Plugin Writers Guide. Examples of such custom bins are the playbin and decodebin elements from gst-plugins-base.