Seamless switching between multiple pre-encrypted video files

• US 7,317,797 B2
• Filed: 06/06/2003
• Issued: 01/08/2008
• Est. Priority Date: 06/07/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Vince, Lawrence D.
• Primary Examiner(s): Barron; Gilberto
• Assistant Examiner(s): LEMMA, SAMSON B
• Application Number:
  US10/455,835
• Publication Number:
  US 20030228018A1
• Time in Patent Office: 1,677 Days
• Field of Search: 380/239, 380/201, 380/204, 380/206
• US Class Current: 380/239
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23473 by pre-encrypting
• CPC Class Codes: H04N 21/2387 Stream processing in response to a playback request from an end-user, e.g. for trick-play
• CPC Class Codes: H04N 21/26606 for generating or managing entitlement messages, e.g. Entitlement Control Message [ECM] or Entitlement Management Message [EMM] arrangements for conditional access to broadcast information or to broadcast-related services H04H60/14
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 21/8541 involving branching, e.g. to different story endings
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

In a video on demand (VOD) system, methods and apparatus are provided for seamlessly switching back and forth between two pre-encrypted files having changing encryption keys. Such switching back and forth may be required when a VOD server stores both a “normal” copy of a movie and a “special” copy such as a “trick-play” version for, e.g., fast forward and rewind effects. Instead of using keys with changing parities in both streams, the special stream is encrypted with keys using the same parity (even or odd), while the normal stream is encrypted with one dynamic key (odd or even) and one fixed key (even or odd). Other special streams, such as scene branch streams and alternate angle streams can also be accommodated.

Claims

1. A method for pre-encrypting video on demand (VOD) content which includes a first video file and at least one second video file, comprising:

encrypting the first video file using a fixed key having a first parity alternating with a dynamic key having a second parity opposite the first parity; and

encrypting the at least one second video file using a fixed key having a fixed parity.

2. A method in accordance with claim 1, wherein:

the fixed parity is the first parity.

3. A method in accordance with claim 1, further comprising:

alternately providing the first and second files to a user as video streams in response to the user interactively transitioning between the first and second files.

4. A method in accordance with claim 1, wherein:

the first video file is a normal video file; and

the second video file is a special trick play file associated with the normal video file.

5. A method in accordance with claim 1, wherein:

the first video file is a normal video file; and

the second video file is a scene branch file.

6. A method in accordance with claim 1, wherein:

the first video file is a normal video file; and

the second video file is an alternate camera angle file.

7. A method in accordance with claim 1, wherein a plurality of second video files are provided and encrypted.

8. A method in accordance with claim 7, wherein:

the first video file is a normal video file; and

at least one of the plurality of second video files is a special trick play file associated with the normal video file.

9. A method in accordance with claim 7, wherein:

the first video file is a normal video file; and

at least one of the plurality of second video files is a scene branch file.

10. A method in accordance with claim 7, wherein:

the first video file is a normal video file; and

at least one of the plurality of second video files is an alternate camera angle file.