+<!-- ============================================================== -->
+<chapter xmlns="http://docbook.org/ns/docbook" version="5.0" xml:lang="en">
+<title>Manipulating existing DCPs</title>
+
+<para>
+Frequently DCP-o-matic is used to take content in formats such as MP4
+and convert it to JPEG2000 for a DCP. Alternatively, it can be used
+to take existing DCPs and modify them in various ways.
+</para>
+
+<section>
+<title>Importing a DCP into DCP-o-matic</title>
+
+<para>
+If you want to do something to an existing DCP the first step is to
+import it. Click <guilabel>Add folder...</guilabel> and select your
+DCP's folder. It will be added to the DCP-o-matic project. If the
+DCP is unencrypted you can preview it in the normal way, though
+playback will be very slow as decoding of DCPs is almost as
+computationally intensive as encoding them.
+</para>
+
+</section>
+
+<section>
+<title>Decrypting encrypted DCPs</title>
+
+<para>
+DCPs can be encrypted (see <xref linkend="ch-encryption"/> for
+details). If you import an encrypted DCP you will need a key, in the
+form of a Key Delivery Message (KDM), to decrypt it.
+</para>
+
+<para>
+KDMs must be prepared by the organisation which created the DCP. They
+contain the keys to decrypt the DCP wrapped up in such a way that only
+the intended recipient can read them. You will need to provide the
+organisation with a certificate which identifies your copy of
+DCP-o-matic and allows them to create a KDM for you.
+</para>
+
+<para>
+To get DCP-o-matic's decryption certificate, open the Preferences
+dialogue (see <xref linkend="ch-preferences"/>) and go to the
+<guilabel>Keys</guilabel> tab. Click the <guilabel>Export DCP
+decryption certificate...</guilabel> button at the bottom of this tab
+and save the certificate. Send this certificate to the DCP creators
+and they can create a KDM to allow DCP-o-matic to decrypt their DCP.
+</para>
+
+<para>
+Once you have your KDM, right-click the DCP's name in DCP-o-matic and
+choose <guilabel>Add KDM...</guilabel>. Specify your KDM and (all
+being well) the DCP will be decrypted and become available for preview.
+</para>
+
+</section>
+
+
+
+</chapter>
+<!-- ============================================================== -->
+
+