Patent ID: 7483532

Claim:
An apparatus comprising: means for encrypting a data stream with an arbitrary block size to form a plurality of encryption units; means for transforming packets of Advanced Systems Format (ASF) audio and video data into RTP packets, wherein the audio and video data are packetized separated; means for preserving block boundaries for each payload, wherein the block boundaries for each payload are determined by a corresponding separate audio and video payloads of ASF formats; means for putting a payload of different data streams into separate RTP packets; means for packetizing the plurality of encryption units into a plurality RTP packets each including: an RTP packet header; one or more payloads of a common data stream and selected from the group consisting of: one or more encryption units; fragment of one encryption unit; and one RTP payload format header for each payload and including, for the corresponding encryption units, a boundary for the arbitrary block size; wherein there is a separation of audio data and video data into the RTP packets, without containing mixed media payloads; wherein the RTP packet header of each packet contains information relating to the separation of the audio data and video data; wherein the block boundaries for each payload are preserved for the original audio and video data that were encrypted and packetized can be reconstructed by decryption.