gstreamer/docs/manual/states-api.xml

<chapter id="chapter-states-api">
  <title>Element states</title>
  <sect1 id="section-states-api">
    <title>Changing element state</title>
    <para> 
      The state of an element can be changed with the following code:
    </para>
    <programlisting>
  GstElement *bin;

  // create a bin, put elements in it and link them
  ...
  gst_element_set_state (bin, GST_STATE_PLAYING);
  ...
    </programlisting>

    <para> 
      You can set the following states on an element:
    </para>
    <informaltable pgwide="1" frame="none" role="enum">
    <tgroup cols="2">
    <tbody>
      <row>
        <entry><literal>GST_STATE_NULL</literal></entry>
        <entry>Reset the state of an element.
        </entry>
      </row>
      <row>
        <entry><literal>GST_STATE_READY</literal></entry>
        <entry>will make the element ready to start processing data.
        </entry>
      </row>
      <row>
        <entry><literal>GST_STATE_PAUSED</literal></entry>
        <entry>temporary stops the data flow.
        </entry>
      </row>
      <row>
        <entry><literal>GST_STATE_PLAYING</literal></entry>
        <entry>means there really is data flowing through the graph.
        </entry>
      </row>
    </tbody>
    </tgroup>
    </informaltable>

  </sect1>
</chapter>