Connecting elements
You can connect the different pads of elements together so that the elements
form a chain.
Visualisation of three connected elements
By connecting these three elements, we have created a very simple
chain. The effect of this will be that the output of the source element
(element1) will be used as input for the filter element (element2). The
filter element will do something with the data and send the result to
the final sink element (element3).
Imagine the above graph as a simple MPEG audio decoder. The source
element is a disk source, the filter element is the MPEG decoder and
the sink element is your audiocard. We will use this simple graph to
construct an MPEG player later in this manual.
Making simple connections
You can connect two pads with:
GstPad *srcpad, *sinkpad;
srcpad = gst_element_get_pad (element1, "src");
sinpad = gst_element_get_pad (element2, "sink");
// connect them
gst_pad_connect (srcpad, sinkpad);
....
// and disconnect them
gst_pad_disconnect (srcpad, sinkpad);
A convenient shortcut for the above code is done with the gst_element_connect_pads ()
function:
// connect them
gst_element_connect_pads (element1, "src", element2, "sink");
....
// and disconnect them
gst_element_disconnect_pads (element1, "src", element2, "sink");
An even more convenient shortcut for single-source, single-sink elements is the
gst_element_connect () function:
// connect them
gst_element_connect (element1, element2);
....
// and disconnect them
gst_element_disconnect (element1, element2);
If you have more than one element to connection, the gst_element_connect_many () function takes
a NULL-terminated list of elements:
// connect them
gst_element_connect_many (element1, element2, element3, element4, NULL);
....
// and disconnect them
gst_element_disconnect_many (element1, element2, element3, element4, NULL);
You can query if a pad is connected with GST_PAD_IS_CONNECTED (pad).
To query for the GstPad a pad is connected to, use
gst_pad_get_peer (pad).
Making filtered connections
You can also force a specific media type on the connection by using gst_pad_connect_filtered ()
and gst_element_connect_filtered (). FIXME link to caps documentation.