A method of processing content in a video on demand (VOD) system
consistent with certain embodiments of the invention, wherein the content
is identified by a first set of packet identifiers (PIDs), involves
receiving content, the content having marked packets designating packets
that are to be encrypted by a first encryption system by setting an
encryption flag for all packets designated to be encrypted. Packets are
selected in the content according to a selective encryption selection
criterion to produce selected packets. The selected packets are
duplicated to produce duplicate copies of the selected packets and these
duplicate copies are identified using a second set of PIDs. The duplicate
copies identified by the second set of PIDs are inserted into the
content. All encryption flags in the content are cleared except for the
selected packets having the first set of PIDs, so the encryption to
follow is selective. This abstract is not to be considered limiting,
since other embodiments may deviate from the features described in this
abstract.