CPC H04L 65/70 (2022.05) [H04N 19/167 (2014.11); H04N 19/172 (2014.11); H04N 19/176 (2014.11); H04N 21/234327 (2013.01)] | 20 Claims |
1. Apparatus for downloading an ROI-specific video stream (40) by tile-based video streaming, the apparatus comprising a processor implemented system configured to inspect a manifest file (24) so as to, depending on a region of interest (ROI) (22), identify and download a set (32) of bit streams (12) along with an extractor (20), the set (32) of bitstreams (12) having encoded thereinto different portions (14) of a video picture area (16);
compile, using the extractor (20), a compiled bitstream (40) out of the set (32) of bitstreams by
extracting, from each of the set (32) of bitstreams, a picture portion (34) relating to a current picture frame (30) by parsing the respective bitstream and
forming the compiled bitstream (40) out of the extracted picture portions (34) so that the compiled bitstream (40) comprises a sub-picture portion (44) for the picture portion (34) of each of the set of bitstreams the compiled bitstream (40) is formed of; and
decrypt a coding payload section (48) of each subpicture portion (44) of a subset of one or more of the subpicture portions (44) of the compiled bitstream (40) 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 (48) of each subpicture portion (44) to be decrypted by
parsing (102) the coding payload section (48) of the respective subpicture portion (44) up to a currently decrypted position and/or
deriving a length of the coding payload section of the respective subpicture portion from a header (46) within the respective subpicture portion (44), and/or
using a bitstream length or pointer indication signaled within the bitstream from which the picture portion is extracted which the respective subpicture portion belongs to.
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