METHOD AND DEVICE TO TRANSFER A VIDEO STREAM BETWEEN A HOST DEVICE AND AN ELECTRONIC DESCRAMBLING DEVICE

摘要

A method to transfer a video stream from a host device comprising a controller configured for bulk transfers to a descrambling device, comprises: forming a chain out transfer comprising a chain out header linked with multiple chain out descriptors, the first chain out descriptor pointing to an out description packet containing at least one producer ID, the second and subsequent chain out descriptor pointing to chunks from the video stream, the last chain out descriptor being configured to generate an interrupt; forming a chain in transfer comprising a chain in header linked with a plurality of chain in descriptors, each chain in descriptor pointing to a descrambled chunk; requesting the controller to process the chain; receiving the description packet by the descrambling device and using key data associated with the chunks to descramble them; receiving by the controller the descrambled chunks and triggering an interrupt on the last chunk.