Patent ID: 11943274
Assignee: FRAUNHOFER GESELLSCHAFT ZUR FÖRDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 16:
17. Method for recovering a video stream from a bitstream which comprises sub-picture portions for different portions of a video picture area, the method comprising:
decrypting a coding payload section of each subpicture portion of a subset of one or more of the subpicture portions of the bitstream by using block-wise decryption by use of sequential variation of a plaintext mask and/or block-decryption key by reinitializing the sequential variation for each subpicture portion to be decrypted and finding a border of the coding payload section of each subpicture portion to be decrypted by
parsing the coding payload section of the respective subpicture portion up to a currently decrypted position and/or

deriving a length of the coding payload section of the respective subpicture portion from a header within the respective subpicture portion, and/or
using a bitstream length or pointer indication signaled from outside for the respective subpicture portion.