 interface to the outside world. Data streams from one element&rsquo;s source pad to another element&rsquo;s sink pad. The specific type of media that the element can handle will be exposed by the pad&rsquo;s capabilities.</div></p><p>A pad is defined by two properties: its direction and its availability. A pad direction can be a <a name="(tech._source._pad)"></a><span style="font-style: italic">source pad</span> or a <a name="(tech._sink._pad)"></a><span style="font-style: italic">sink pad</span>. Elements