Generation of encrypted video information
AssigneeKoninklijke Philips Electronics N.V.
InventorsSjoerd Zwart, Pieter-Jelle Gerbrandts, Tom Kan
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Abstract
An encrypted stream of video information (20) contains first video frames (22) and second video frames which are accessible and not accessible during trick play respectively. From a source stream encrypted that is for decryption with repeatedly changing control words sections of the stream are identified where respective first ones of the frames occur in the stream. Control words for decryption (24) are included in the stream. At least part of the control words are included in the stream at positions selected synchronized to the identified sections.
Claims11
A method of generating an encrypted stream (20) of video information, representing video frames, comprising first ones of the video frames and second ones of the video frames which are accessible and not accessible during a special mode of play of the stream respectively, the method comprising the steps of
- providing a source stream encrypted for decryption with repeatedly changing control words;
- identifying sections (22) of the stream of respective first ones of the frames occur in the stream (20);
- including items of decryption information in the stream (20) to provide respective control words in advance of locations after which the respective control words are required for decryption, at least part of the items of decryption information being included in the stream at positions (24) selected synchronized to the sections (22).
An encrypted stream of video information (20), representing video frames, first ones of the video frames being encoded by themselves, second ones of the video frames being encoded by means of updates, the stream comprising
- successive crypto periods (26), information in successive ones of the crypto periods being decryptable with successively different control words;
- each first one of the frames in a respective section (22) of the stream;
- items of decryption information in the stream to provide respective control words in advance of locations after which the respective control words are required for decryption, at least part of the items of decryption information being included in the stream at positions (24), each position (24) synchronized in the same way to a respective one of the sections (22).
An apparatus for generating an encrypted stream (20) of video information, representing video frames, comprising first ones of the video frames and second ones of the video frames which are accessible and not accessible during a special mode of play of the stream (20) respectively, the apparatus comprising
- a section identification unit (123), for identifying sections (22) of the stream (20) of respective first ones of the frames occur in the stream (20);
- an insertion unit (121) for inserting items of decryption information in the stream (20) to provide respective control words in advance of locations after which the respective control words are required for decryption, the insertion unit being triggered by section identification unit (123) to include at least part of the items of decryption information in the stream (20) at positions (24) synchronized to the detected sections (22).
Dependencies are inferred from the claim text.