Obscuring data in an audiovisual product

• US 20050019017A1
• Filed: 06/07/2004
• Published: 01/27/2005
• Est. Priority Date: 06/05/2003
• Status: Active Grant

• Current Assignee: ZOO Digital Ltd. (ZOO Digital Group Plc)
• Original Assignee: ZOO Digital Ltd. (ZOO Digital Group Plc)
• Inventors: Green, Stuart
• Granted Patent: US 7,912,351 B2
• Time in Patent Office: Days
• US Class Current: 386/234
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00152 involving a password
• CPC Class Codes: G11B 20/00166 involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00927 wherein said defects or errors are generated on purpose, e.g. intended scratches
• CPC Class Codes: G11B 20/00942 said intentional errors occurring due to an invalid playback path or program chain
• CPC Class Codes: G11B 2220/213 Read-only discs
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/25816 involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 9/8042 involving data reduction
• CPC Class Codes: H04N 9/8047 using transform coding
• CPC Class Codes: H04N 9/8205 involving the multiplexing of an additional signal and the colour video signal
• CPC Class Codes: H04N 9/8227 the additional signal being at least another television signal

Abstract

Access to an audiovisual product is controlled by obscuring data. Cells 420 of audiovisual data A,B,C are reproduced by a sequence instruction 410 (e.g. a PGC or Program Chain). One such sequence instruction 410a correctly reproduces the audiovisual data A,B,C, but is hidden amongst many other sequence instructions 410b which incorrectly reproduce the sequence of cells 420 (e.g. as BAC, ACB, CAB, etc.).

Claims

1. A method for use in creating an audiovisual product, comprising the steps of:

receiving original audiovisual data intended for playback according to an original content sequence;

dividing the original audiovisual data into a plurality of cells; and

creating a plurality of sequence instructions each representing a playback sequence for playing back the cells in a specified order, including;

at least one correct sequence instruction where the playback sequence reproduces the original content sequence; and

a plurality of incorrect sequence instructions where the playback sequence does not reproduce the original content sequence.

2. The method of claim 1, wherein the dividing step comprises arranging the cells other than according to the original content sequence.

3. The method of claim 1, comprising arranging the cells into a jumbled arrangement such that the original content sequence is scrambled.

4. The method of claim 1, comprising creating relatively many of the incorrect sequence instructions and relatively few of the correct sequence instructions, such that the relatively few correct sequence instructions are obscured amongst the relatively many incorrect sequence instructions.

5. The method of claim 1, wherein the incorrect sequence instructions each result in an unsatisfactory playback of the audiovisual data in the cells.

6. The method of claim 1, wherein the dividing step comprises adding one or more erroneous cells that are not proper to the original content sequence.

7. The method of claim 6, wherein the or each of the erroneous cells contain a section of the original audiovisual data.

8. The method of claim 7, comprising distorting the original audiovisual data in the erroneous cells.

9. The method of claim 1, wherein the plurality of sequence instructions implement different variations on the way in which the audiovisual data in the cells are played, but without duplicating the audiovisual data itself.

10. The method of claim 1, wherein the plurality of sequence instructions are formed as a permuted sequence such that the incorrect sequence instructions are permutations of the correct sequence instruction.

11. The method of claim 1, comprising the steps of:

providing a plurality of structure locations within the audiovisual product; and

allocating the plurality of sequence instructions to the plurality of structure locations.

12. The method of claim 11, wherein:

the structure location allocated to the or each at least one correct sequence instruction is derivable from an access code.

13. The method of claim 12, comprising the steps of:

defining a destination function that when applied to the access code derives the structure location of the correct sequence instruction.

14. The method of claim 13, wherein the access code comprises a numerical value within a predetermined range, such that the destination function when applied to the numerical value of the access code calculates the structure location of the correct sequence instruction.

15. The method of claim 14, wherein the destination function when applied to an incorrect numerical value calculates the structure location of one of the incorrect sequence instructions.

16. The method of claim 13, wherein the destination function comprises a one way hash function.

17. The method of claim 13, wherein the destination function operates on at least two access codes each having numerical values.

18. The method of claim 13, wherein the destination function is applied to generate a first access code for display to a user, and to operate on a second access code provided in return.

19. The method of claim 18, wherein the destination function comprises generating a seed and applying a transformation to generate the first access code, such that a seed of the first access code is not revealed to a user.

20. The method of claim 1, wherein the plurality of sequence instructions are formed as a plurality of Program Chains (PGCs).

21. The method of claim 1, further comprising:

adding at least one erroneous cell containing erroneous audiovisual data to the plurality of cells.

22. The method of claim 1, further comprising:

allocating the plurality of cells amongst at least a first video stream and a second video stream; and

creating a video stream switch instruction to switch between the first and second video streams, thereby reproducing the cells according to the original content sequence.

23. The method of claim 1, wherein the audiovisual product is playable according to a DVD-Video specification.

24. The method of claim 1, comprising recording the audiovisual product onto a portable random-access storage medium.

25. The method of claim 1, comprising recording the audiovisual product onto an optical disk according to a DVD-Video specification.

36. A recording medium having recorded thereon computer implementable instructions for performing the method of claim 1.

38. An authoring apparatus adapted to perform the method of claim 1.

40. An audiovisual product operable to perform the method of claim 1.

42. A DVD-Video recording and/or reproducing apparatus adapted to perform the method of claim 1.

26. A method for use in reproducing an audiovisual product, comprising the steps of:

receiving an audiovisual product having a plurality of cells of audiovisual data whose playback is controlled by a plurality of sequence instructions, wherein the plurality of sequence instructions include at least one correct sequence instruction for reproducing the audiovisual product according to an original playback sequence, and a plurality of incorrect sequence instructions which do not reproduce the audiovisual product according to the original playback sequence;

selecting one amongst the plurality of sequence instructions; and

reproducing the audiovisual data in the cells according to the selected sequence instruction.

27. The method of claim 26, wherein each of the sequence instructions has a predetermined structure location within the audiovisual product, and the selecting step comprises:

receiving an access code;

applying a destination function to the access code and thereby determining a destination structure location within the audiovisual product; and

jumping to the determined destination structure location to thereby select the sequence instruction corresponding to that location.

28. The method of claim 27, wherein the access code is input by a user during playback of the audiovisual product.

29. The method of claim 27, wherein the access code is input by a user through a user input device such as a keypad or remote control unit or other communications device.

30. The method of claim 27, wherein the destination function applied to the access code is a mathematic function that returns a destination structure location dependent upon the received access code.

31. The method of claim 26, further comprising:

receiving the audiovisual product having audiovisual data divided into a plurality of cells, including at least one correct cell containing correct audiovisual data proper to an original content sequence, and at least one erroneous cell containing erroneous audiovisual data, and at least one sequence instruction representing a playback sequence for playing back selected ones of the plurality of cells in a specified order; and

reproducing the audiovisual data in the cells according to the sequence instruction.

32. The method of claim 26, further comprising:

receiving an audiovisual product having a plurality of cells of audiovisual data which together represent an original content sequence, wherein the cells are divided amongst at least first and second video streams; and

performing one or more video stream switch instructions to automatically switch between at least the first video stream and the second video stream during reproduction of the cells, thereby reproducing the audiovisual data according to the original content sequence.

33. The method of claim 26, wherein the audiovisual product is playable according to DVD-Video specifications.

34. The method of claim 26, comprising reproducing the audiovisual product from a portable random-access storage medium.

35. The method of claim 26, comprising reproducing the audiovisual product from an optical disk according to a DVD-Video specification.

37. A recording medium having recorded thereon computer implementable instructions for performing the method of claim 26.

39. An authoring apparatus adapted to perform the method of claim 26.

41. An audiovisual product operable to perform the method of claim 26.

43. A DVD-Video recording and/or reproducing apparatus adapted to perform the method of claim 26.